JP2022138778A - Light source device and image projection device - Google Patents

Abstract

To effectively prevent an increase in temperature of a wavelength conversion element in a small-sized light source device.SOLUTION: A light source device has: a light source 21; a wavelength conversion element 2510 that converts the wavelength of excitation light emitted from the light source; and a heat radiation member 2530 that is arranged on the opposite side of an excitation light irradiation side of the wavelength conversion element. A plurality of parts to be irradiated 2512 separated from each other in the wavelength conversion element are irradiated with the excitation light. The wavelength conversion element has a first opening 2511 between the plurality of parts to be irradiated, and the heat radiation member has a second opening 2531 connected to the first opening.SELECTED DRAWING: Figure 3

Description

The present invention relates to a light source device suitable for an image projection device (projector).

In a light source device used in a projector, excitation light such as blue light emitted from a laser light source is irradiated to a wavelength conversion element such as a phosphor, and the wavelength-converted light such as yellow light is used to generate white illumination light. There is something to generate When the wavelength conversion element converts the wavelength of the excitation light, it absorbs part of the excitation light and generates heat. However, the wavelength conversion efficiency decreases due to the temperature rise of the wavelength conversion element. Therefore, it is necessary to cool the wavelength conversion element.

As a method of cooling the wavelength conversion element, there is a method of attaching a heat radiation member such as a heat sink to the wavelength conversion element. In Patent Document 1, a wavelength conversion element is provided on a heat-dissipating base material, and excitation light is applied to a plurality of locations of the wavelength conversion element to disperse the heat-generating portions, thereby suppressing the temperature rise of the wavelength conversion element. is disclosed.

JP 2019-28120 A

However, in the light source device of Patent Literature 1, if sufficient intervals are not secured between a plurality of irradiation points (heat generating portions) of excitation light, heat interference occurs between the heat generating portions and the effect of suppressing temperature rise is reduced. On the other hand, if the distance between the irradiation points is widened, the size of the light source device increases.

SUMMARY OF THE INVENTION The present invention provides a light source device capable of effectively suppressing a temperature rise of a wavelength conversion element while being miniaturized, and an image projection device having the same.

A light source device as one aspect of the present invention includes a light source, a wavelength conversion element that converts the wavelength of excitation light emitted from the light source, and a wavelength conversion element arranged on the opposite side of the wavelength conversion element from the irradiation side of the excitation light. and a heat dissipating member. The excitation light is applied to a plurality of irradiated portions of the wavelength conversion element that are spaced apart from each other. The wavelength conversion element has a first opening between the plurality of irradiated portions, and the heat dissipation member has a second opening connected to the first opening. An image projection device including the light source device also constitutes another aspect of the present invention.

According to the present invention, it is possible to effectively suppress the temperature rise of the wavelength conversion element while downsizing the light source device.

FIG. 2 is a diagram showing the optical configuration of the projector according to the first embodiment; FIG. 4 is a diagram showing an optical configuration of a color separation/synthesis optical system in the projector according to the first embodiment; FIG. 3 is an exploded perspective view of a phosphor unit in the projector of Example 1. FIG. FIG. 3 is a view of the phosphor unit in Example 1 as seen from the direction of light incidence. 4 is a diagram showing the flow of cooling air within the phosphor unit in Example 1. FIG. (a) A diagram showing the spread of heat in the phosphor when no opening is provided in the heat sink in the conventional phosphor unit and (b) when the opening is provided in Example 1, and (c) the temperature distribution of the phosphor. illustration. FIG. 4 is a diagram showing the flow of cooling air in the phosphor unit according to the first embodiment; FIG. 10 is a diagram showing the flow of cooling air in the phosphor unit according to the second embodiment;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 FIG. 1 shows the optical configuration of a projector 10 as an image projection apparatus that is Embodiment 1 of the present invention. The projector 10 has a first light source optical system 20 , a second light source optical system 30 , an illumination optical system 40 , a color separation/synthesis optical system 50 and a projection lens (projection optical system) 60 . A light source device is configured by the first and second light source optical systems 20 and 30 .

The first light source optical system 20 has a first laser diode (LD) 21 as a light source, a first collimator optical system 22, a dichroic mirror 23, a condenser lens array 24, a phosphor unit 25 and an afocal lens 26. .

1st LD21 emits the laser beam (henceforth blue light) of the wavelength of a blue band. The blue light emitted from the first LD 21 as divergent light enters collimator lenses 22 a and 22 b constituting the first collimator optical system 22 , is collimated, and enters the dichroic mirror 23 . The dichroic mirror 23 has a property of reflecting light in the blue band and transmitting light in other bands, and reflects the blue light from the first collimator optical system 22 . The reflected blue light enters condenser lens array 24 . The condenser lens array 24 has a plurality of lenses arranged in a grid pattern, and splits the incident blue light into a plurality of lights traveling along a plurality of optical paths. The blue light traveling through multiple optical paths is applied to the phosphor unit 25 as excitation light.

FIG. 3 shows the configuration of the phosphor unit 25. As shown in FIG. Phosphor unit 25 has phosphor 2510 as a wavelength conversion element. The phosphor 2510 is formed of a material obtained by mixing a fluorescent material for wavelength-converting blue band excitation light into yellow band fluorescent light (wavelength conversion light) and a diffusion material for diffusely reflecting the excitation light using a binder. It is Fluorescent light generated by wavelength conversion from excitation light by phosphor 2510 is reflected by reflective layer 2522 provided on substrate 2520 holding phosphor 2510 and emitted from phosphor unit 25 . In this embodiment, as described above, the excitation light is incident on the phosphor unit 25 through a plurality of optical paths, so that fluorescent light is emitted from the phosphor unit 25 as well along a plurality of optical paths. A detailed configuration of the phosphor unit 25 will be described later. In addition, although a reflective phosphor unit is used in this embodiment, a transmissive phosphor unit may be used.

In FIG. 1, the fluorescent light diffusely emitted from the phosphor unit 25 so as to travel along a plurality of optical paths is transmitted through the condenser lens array 24 and combined to travel along one optical path again. Fluorescent light emitted from the condenser lens array 24 passes through the dichroic mirror 23 and enters the afocal lens 26 .

On the other hand, the second light source optical system 30 has a second LD 31 that emits blue light as laser light, condenser lenses 32 a and 32 b, a diffusion plate 33 and a second collimator optical system 34 .

The blue light emitted radially from the second LD 31 is condensed by the condenser lenses 32 a and 32 b and enters the diffusion plate 33 . The blue light is diffused and transmitted by the diffuser plate 33 , collimated by collimator lenses 34 a and 34 b constituting the second collimator optical system 34 , and emitted from the second light source optical system 30 . The blue light emitted from the second light source optical system 30 is reflected by the dichroic mirror 23 and enters the afocal lens 26, where it is combined with the fluorescent light that has entered the afocal lens 26 from the first light source optical system 20. . This produces white illumination light.

The afocal lens 26 expands or compresses the beam diameter of the collimated beam when the collimated beam is incident. The illumination light passes through the afocal lens 26 and enters the illumination optical system 40 as a luminous flux having an appropriate luminous flux diameter to the subsequent illumination optical system 40 .

The illumination optical system 40 has fly-eye lenses 41 and 42 , a polarization conversion element 43 and condenser lenses 44 , 45 and 46 . The illumination light emitted from the afocal lens 26 is split into a plurality of light beams by the fly-eye lenses 41 and 42 and enters the polarization conversion element 43 . The polarization conversion element 43 converts incident unpolarized light into linearly polarized light having a predetermined polarization direction. The illumination light as a plurality of light beams converted into linearly polarized light by the polarization conversion element 43 is condensed by the condenser lenses 44 , 45 and 46 and directed to the color separation/synthesis optical system 50 . Note that the condenser lenses 44, 45, and 46 converge the illumination light as a plurality of light beams so as to be superimposed on a liquid crystal panel, which will be described later. This makes it possible to uniformly illuminate the liquid crystal panel.

FIG. 2 shows the optical configuration of the color separation/synthesis optical system 50. As shown in FIG. The color separation/synthesis optical system 50 includes a cross dichroic mirror 51, two reflecting mirrors 52, a dichroic mirror 53, condenser lenses 54R, 54G and 54B, λ/2 plates 55R, 55G and 55B, and reflective polarizing plates 56R and 56G. 56B. The color separation/combination optical system 50 includes wire grid (WG) polarizers 57R, 57G, and 57B, retardation compensation plates 58R, 58G, and 58B, reflective liquid crystal panels 59R, 59G, and 59B as light modulation elements, and color combination optical system 50. It has a prism CP.

The cross dichroic mirror 51 splits the white illumination light into red (R) light, green (G) light and blue (B) light. The R light from the cross dichroic mirror 51 is reflected by one of the reflecting mirrors 52 and passes through the condenser lens 54R, the λ/2 plate 55R, the reflective polarizing plate 56R, the WG polarizer 57R and the phase difference compensating plate 58R. It is incident on the reflective liquid crystal panel 59R.

Also, the BG light from the cross dichroic mirror 51 is reflected by the other reflecting mirror 52 and enters the dichroic mirror 53 . The dichroic mirror 53 has a characteristic of transmitting B light and reflecting G light. The G light reflected by the dichroic mirror 53 is transmitted through the condenser lens 54G, the λ/2 plate 55G, the reflective polarizing plate 56G, the WG polarizer 57G and the retardation compensating plate 58G, and enters the reflective liquid crystal panel 59G. . The B light that has passed through the dichroic mirror 53 passes through the condenser lens 54B, the λ/2 plate 55B, the reflective polarizing plate 56B, the WG polarizer 57B and the retardation compensating plate 58B, and enters the reflective liquid crystal panel 59B.

Each reflective liquid crystal panel has a function of modulating and reflecting incident light according to a video signal input to the projector. The R light, G light and B light modulated and reflected by the reflective liquid crystal panels 59R, 59G and 59B are respectively reflected by the WG polarizers 57R, 57G and 57B and guided to the color synthesizing prism CP. and enter the projection lens 60 as projection light.

Projection light is projected onto a projection surface such as a screen (not shown) by a projection lens 60 . Thereby, a color image as a projection image is displayed on the projection surface. In this embodiment, a reflective liquid crystal panel is used as the light modulating element, but a transmissive liquid crystal panel may be used, or a digital micromirror device may be used.

Next, a detailed configuration of the phosphor unit 25 will be described with reference to FIGS. 3 and 4. FIG. FIG. 3 shows the phosphor unit 25 exploded, and FIG. 4 shows the phosphor unit 25 viewed from the direction in which excitation light and fluorescence light enter and exit (light irradiation direction: hereinafter referred to as light incidence and emission direction). .

The phosphor unit 25 has the phosphor 2510 described above, a substrate 2520 to which the phosphor 2510 is applied, and a radiator (heat sink) 2530 as a heat dissipation member attached to the substrate 2520 . The heat sink 2530 is arranged on the side opposite to the irradiation side of the excitation light with respect to the phosphor 2510 and is thermally connected to the phosphor 2510 via the substrate 2520 .

The radiator 2530 has a base portion 2530a attached to the substrate 2520 and a plurality of plate-like fin portions 2530b extending from the base portion 2530a, and is cooled by cooling air from a cooling fan which will be described later. Excitation light BL as blue light that has traveled through a plurality of optical paths enters the phosphor unit 25 in the direction indicated by the black arrows, and fluorescence light YL is emitted from the phosphor unit 25 in the direction indicated by the white arrows. In this embodiment, the material of the substrate 2520 is a sapphire material having translucency and excellent thermal conductivity. As the material of the radiator 2530, a material having excellent thermal conductivity such as aluminum or copper is used.

The phosphor 2510 has a plurality of (2×2=four in this embodiment) spot portions 2512 as irradiated portions to which the excitation light is irradiated. Phosphor 2510, substrate 2520, and radiator 2530 each have a cross-shaped groove when viewed from the direction of light incidence and emission. opening) 2521 and a radiator opening (second opening) 2531 . The phosphor opening 2511, the substrate opening 2521, and the radiator opening 2531 are connected (communicated) with each other in the thickness direction. In the following description, phosphor aperture 2511 , substrate aperture 2521 and radiator aperture 2531 are collectively referred to as aperture 2550 .

In this embodiment, as shown in FIG. 4, openings 2550 are formed between adjacent spot portions 2512 in four spot portions 2512 . L in FIG. 4 represents a straight line connecting the adjacent spot portions 2512, and the opening 2550 is formed in a linear shape that intersects the straight line L. As shown in FIG.

In this embodiment, four spot portions 2512 are provided on a single phosphor unit 25, and openings 2550 are provided between the spot portions 2512 adjacent to each other. This is because if four separate phosphor units are arranged with a gap corresponding to the opening 2550, it becomes necessary to control the positional accuracy of each phosphor unit in the direction of light incidence and emission, which complicates manufacturing. Therefore, it is possible to avoid this.

However, a plurality of phosphors each having a spot portion may be spaced apart from each other on a single substrate 2520 . This is because, in this case, it is unnecessary to manage the positional accuracy of each phosphor in the direction of light incidence and emission. A gap between the phosphors (spot portions) generated by separating the plurality of phosphors from each other becomes the phosphor aperture. That is, the phosphor aperture may be formed in a part of a single phosphor as shown in FIGS. 3 and 4, or may be formed as a gap between a plurality of phosphors separated from each other. good.

Next, a configuration for cooling the phosphor unit 25 in this embodiment will be described with reference to FIG. FIG. 5 shows a cross section (AA' cross section) when the phosphor unit 25 is cut along line AA' shown in FIG. showing.

When the spot portion 2512 is irradiated with blue excitation light emitted from the first LD 21 , the phosphor 2510 absorbs part of the excitation light to generate heat from the spot portion 2512 . The heat generated from the spot portion 2512 is transferred to the base portion 2530a of the radiator 2530 through the substrate 2520. FIG. The radiator 2530 diffuses the heat transmitted to the base portion 2530a by the fin portion 2530b having a large surface area. Cooling air from a cooling fan 2540 as a coolant flow generating means is blown against the fin portion 2530b. A sirocco fan, an axial fan, or the like can be used as the cooling fan 2540 .

The cooling air flowing into the fin portion 2530b in the direction along the base portion 2530a is composed of the first cooling air flowing out from the opposite side of the fin portion 2530b and the first cooling air flowing to the surface side of the phosphor 2510 through the openings 2550. It divides into 2 cooling air. The first cooling air releases the heat of the fin portion 2530 b to the outside of the phosphor unit 25 . On the other hand, the second cooling air is used to cool the surface of phosphor 2510 (spot portion 2512) as described later.

Here, FIG. 6A shows the spread of heat when the phosphor unit 25 is not provided with the opening 2550, and FIG. 6B schematically shows the spread of heat when the phosphor unit 25 is provided with the aperture 2550. clearly shown. In FIG. 6A, since the adjacent spot portions 2512 are not insulated at all, thermal interference occurs between the spot portions 2512 . In contrast, in FIG. 6B, openings 2550 provided between adjacent spot portions 2512 have the effect of insulating the spot portions 2512, thereby reducing thermal interference.

FIG. 6(c) shows this. FIG. 6(c) shows the temperature distribution of the phosphor 2510 on the AA' cross section passing through the spot portion 2512 in the above two cases. The vertical axis indicates the temperature, and the horizontal axis indicates the position on the phosphor 2510 . A solid line indicates the temperature distribution when the opening 2550 shown in FIG. 6B is provided, and a dotted line indicates the temperature distribution when the opening 2550 shown in FIG. 6A is not provided.

As can be seen from FIG. 6(c), when the opening 2550 is provided, unlike the case where the opening 2550 is not provided, a low-temperature adiabatic region (valley portion of the temperature distribution) is formed between the adjacent spot portions 2512. be. As a result, when the opening 2550 is provided, the temperature of the highest spot portion 2512 (mountain portion of the temperature distribution) is lowered and the temperature of the phosphor 2510 as a whole is lowered as compared to when the opening 2550 is not provided. be able to.

In addition, the second cooling air that has passed through the opening 2550 and flowed to the surface side (excitation light irradiation side) of the phosphor 2510 as described above is arranged to face the phosphor 2510 as shown in FIG. It hits the condenser lens array (optical element) 24 and flows along the surface of the phosphor 2510 . Thereby, the heat of the surface of the phosphor 2510 including the spot portion 2512 can be efficiently released to the outside of the phosphor unit 25 .

Thus, in this embodiment, by providing the opening 2550 in the phosphor unit 25, the effect of heat insulation between the adjacent spot portions 2512 and part of the cooling air flowing into the radiator 2530 from the cooling fan 2540 is 2510 surface leading effect can be obtained. Therefore, phosphor 2510 can be efficiently cooled from both the back surface side in contact with substrate 2520 attached to radiator 2530 and the front surface side where spot portion 2512 is provided.

FIG. 8 illustrates a configuration for cooling the phosphor unit 25 that is Embodiment 2 of the present invention. FIG. 8 shows a cross section corresponding to FIG. 5 in the phosphor unit 25 of this embodiment.

In the first embodiment, the cooling air (refrigerant) from the cooling fan 2540 is introduced into the radiator 2530 in the direction along the base portion 2530a, that is, in the direction perpendicular to the penetrating direction of the opening 2550. did. In contrast, in this embodiment, the cooling air from the cooling fan 2540 is directed toward the radiator 2530 from the direction facing the base portion 2530a (the direction in which the fin portion 2530b extends from the base portion 2530a), that is, from the opening 2550. flow from the penetration direction.

As a result, in this embodiment, more of the cooling air from the cooling fan 2540 can pass through the opening 2550 and be led to the surface side of the phosphor 2510 as compared with the first embodiment. The velocity and volume of cooling air flowing to the face side can be increased. As a result, the heat insulation effect between the adjacent spot portions 2512 by the openings 2550 is equivalent to that of the first embodiment, but the cooling effect of the phosphor 2510 by the cooling air is greater than that of the first embodiment. can be cooled more efficiently. Other configurations of the phosphor unit 25 and the projector are the same as those of the first embodiment.

According to the embodiments described above, it is possible to effectively suppress the temperature rise of the phosphor while downsizing the light source device.

In each of the above-described embodiments, the cooling fan 2540 blows cooling air to the radiator 2530 , but the cooling fan 2540 may be configured to suck air heated from the radiator 2530 .

Also, although air is used as the refrigerant in each of the above embodiments, fluids other than air, such as water and refrigerant liquid, may be used.

Furthermore, in each of the above embodiments, the phosphor aperture, the substrate aperture, and the radiator aperture have the same shape (cross groove shape). However, these shapes may differ from each other. For example, to reduce the thermal interference described above, the phosphor aperture and the substrate aperture may have the same cross groove shape, but the radiator aperture may have one or more circular holes or corners connecting the substrate aperture and the phosphor aperture. It may have a hole shape. That is, the shape of the radiator opening is not limited as long as it is connected to the phosphor opening through the substrate opening. Further, the substrate aperture preferably has the same shape as the phosphor aperture, but may have a different shape from the phosphor aperture.

Each embodiment described above is merely a representative example, and various modifications and changes can be made to each embodiment in carrying out the present invention.

10 Projector 20 First Light Source Optical System 25 Phosphor Unit 2510 Phosphor 2512 Spot Part 2520 Substrate 2530 Radiator 2550 Opening

Claims (9)

a light source;
a wavelength conversion element that converts the wavelength of excitation light emitted from the light source;
a heat dissipation member disposed on the side opposite to the irradiation side of the excitation light with respect to the wavelength conversion element,
The excitation light is applied to a plurality of irradiated portions separated from each other in the wavelength conversion element,
The wavelength conversion element has a first opening between the plurality of irradiated parts,
The light source device, wherein the heat dissipation member has a second opening connected to the first opening. 2. The light source device according to claim 1, wherein said first opening has a shape extending so as to intersect a straight line connecting adjacent irradiated portions among said plurality of irradiated portions. The wavelength conversion element is a single element,
3. The light source device according to claim 1, wherein said first opening is formed in a part of said wavelength conversion element. The wavelength conversion element is composed of a plurality of elements each including the irradiated portion,
3. The light source device according to claim 1, wherein the first opening is formed by arranging the plurality of elements apart from each other. a substrate holding the wavelength conversion element is arranged between the wavelength conversion element and the heat radiation member;
5. The light source device according to any one of claims 1 to 4, wherein the substrate has a third opening communicating with the first and second openings. Having a coolant flow generating means for generating a flow of a coolant for cooling the heat radiating member,
The light source device according to any one of claims 1 to 5, wherein the coolant flows through the second opening and the first opening to the irradiation side. The heat dissipation member has a base portion having the second opening and a plurality of fin portions extending from the base portion,
7. The light source device according to claim 6, wherein the coolant flows from the base portion toward the heat radiating member in a direction in which the fin portion extends. 7. The coolant flowing through the first opening to the irradiation side hits an optical element arranged to face the wavelength conversion element and flows along the wavelength conversion element. 8. The light source device according to 7. a light source device according to any one of claims 1 to 8;
a light modulation element that modulates illumination light generated using the wavelength-converted light from the wavelength conversion element;
An image projection apparatus for displaying an image by projecting light modulated by the light modulation element.

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