WO2016181858A1

WO2016181858A1 - Light source device and projection device

Info

Publication number: WO2016181858A1
Application number: PCT/JP2016/063363
Authority: WO
Inventors: 小林大介
Original assignee: コニカミノルタ株式会社
Priority date: 2015-05-08
Filing date: 2016-04-28
Publication date: 2016-11-17

Abstract

Provided is a light source device (21) generating blue laser beams (L1), red light-source beams (L2), and green fluorescent beams (FL). A reflective liquid crystal element (23) is irradiated with the blue laser beams (L1), the red light-source beams (L2), and the green fluorescent beams (FL), thereby emitting, as reflected light, video light (L4) corresponding to an image. An irregular surface structure having an array of irregularities is formed on a side, of a light-emitted board (35) of the light source device (21), on which excitation light beams (EL) are incident, and an incidence angle of the excitation light beams (EL) is set to be equal to or less than 20° with respect to a direction of a normal line of a phosphor layer.

Description

Light source device and projection device

The present invention relates to a light source device suitable for illumination of an image display element incorporated in a projection device, and a projection device incorporating such a light source device.

In recent years, solid-state light sources such as LEDs and laser diodes (LDs) have come to be used as light sources for projectors. Normally, three colors of red (R), green (G), and blue (B) are used as the light source of the projector, but there is no light source having a desired intensity particularly with G light. On the other hand, for example, a configuration is used in which B light is used as excitation light and wavelength conversion is performed by applying it to a phosphor to obtain G light (see Patent Documents 1 to 3). Specifically, G light is emitted by irradiating excitation light from a B light source onto a light-emitting wheel provided with a phosphor layer containing a phosphor, and G light obtained by excitation is used together with B light or the like for liquid crystal, DMD, or the like. The image formed by the image display element is projected on the screen through the projection optical system by the configuration in which the image display element is irradiated. At that time, it is desirable to illuminate the projection light onto the screen as brightly as possible.
For example, in Patent Document 1, a concavo-convex structure in which regular quadrangular pyramids and the like are two-dimensionally arranged is formed on the excitation light incident surface of the phosphor layer, and the excitation light is diffused in the phosphor layer to spread over a wide range. , Trying to increase the utilization efficiency of excitation light. On the other hand, Patent Document 2 also has a concavo-convex structure in which the concave portions of the inverse regular quadrangular pyramids are two-dimensionally arranged on the excitation light incident surface of the phosphor layer. It is trying to reduce the temperature rise and light saturation phenomenon of phosphor particles.

By the way, in order to brighten the projected image on the screen, it is desirable to reduce the fluorescence etendue so that the fluorescence is incident on the image display element at a desired angle or less. One method for reducing the etendue of fluorescence is to reduce the spot of excitation light on the phosphor layer. In that case, the fluorescence emitted from the phosphor layer usually has a Lambertian distribution, and it is easy to capture light emitted at a large angle with respect to the normal of the light emitting surface where the phosphor layer extends by an optical element such as a lens. In addition, the optical element is increased in size or the optical loss is increased.
In addition, the method of providing a concavo-convex structure on the light emission side as in Patent Document 3 does not necessarily improve the directivity, and is applied as it is to a reflective light emitting wheel that returns fluorescence to the solid light source side. There is also a problem that cannot be done.

JP 2012-68465 A JP 2012-93454 A JP 2012-27052 A

It is an object of the present invention to provide a light source device that can reduce etendue while preventing an increase in size and an increase in light loss, and a projection device incorporating such a light source device.

In order to achieve the above object, a light source device for a projection apparatus according to the present invention includes an excitation light source that emits excitation light, a light irradiation plate that includes a phosphor layer that emits fluorescence when irradiated with excitation light, and A surface uneven structure having an array of unevenness is formed on the surface of the light irradiation plate on which the excitation light is incident, and the incident angle of the excitation light to the light irradiation plate is determined by the method of the phosphor layer It is 20 degrees or less with respect to the line direction.

According to the light source device, since the surface uneven structure having the array of unevenness is formed on the surface of the light irradiation plate on the side where the excitation light is incident, the excitation light is condensed and condensed on the phosphor layer. Thus, an array of light emitting regions can be formed. In addition, when the excitation light is condensed on the array-shaped light emitting region, the incident angle of the excitation light is set to 20 ° or less with respect to the normal direction of the phosphor layer, thereby reducing the size of the array-shaped light emitting region. In addition, since the angle range when the fluorescence is emitted from the light irradiation plate can be narrowed, the etendue can be reliably reduced while preventing an increase in size and an increase in light loss.

A projection device according to the present invention includes the above-described light source device, an image display element illuminated by the light source device, and a projection optical system that projects an image formed by the image display element. In this case, a small and efficient light source device that can reduce the etendue of fluorescence that illuminates the image display element is used, and the light use efficiency in the image display element can be increased, and a small and bright projection device can be provided. it can.

It is a figure explaining the projection apparatus containing the light source device for projection apparatuses which concerns on 1st Embodiment. It is an expanded sectional view explaining the condensing etc. by a condenser lens. 3A is a diagram for explaining an example of a light irradiation plate incorporated in the light source device shown in FIG. 1, FIG. 3B is a diagram for explaining a cross-sectional structure of a first region of the light irradiation plate, and FIG. It is a figure explaining the cross-section of the 2nd area | region of a light irradiation plate. 4A to 4C are conceptual perspective views for explaining the shape of the optical element constituting the surface uneven structure provided on the surface of the light irradiation plate, and FIG. 4D shows the shape of the optical element constituting the surface uneven structure. It is a conceptual sectional view to explain. It is an expanded sectional view explaining advancing of the light around a fluorescent substance layer. It is a figure explaining the light source device etc. for projectors concerning a 2nd embodiment. 7A and 7B are diagrams illustrating the structure of the light irradiation plate incorporated in the light source device shown in FIG.

[First Embodiment]
Hereinafter, a projection apparatus incorporating a light source device for a projection apparatus according to a first embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the projection device 2 according to the first embodiment enables projection of images corresponding to various video signals, and includes a light source device 21, a polarization beam splitter 22, and a reflective liquid crystal element 23. A projection optical system 26 and a video drive circuit 25.

The light source device 21 includes a first beam forming unit 31, a second beam forming unit 131, a polarization dichroic mirror 32, a phase difference plate 33, a condenser lens 34, a light irradiation plate 35, and a fly-eye optical system 36. , A polarization conversion unit 37 and a field lens 38. The first beam forming unit 31 emits laser light L1 having a substantially parallel first wavelength, and the second beam forming unit 131 emits light source light L2 having a substantially parallel second wavelength. The polarization dichroic mirror 32 branches the optical path of the fluorescence FL from the optical path of the laser light L1 and transmits the light source light L2. The phase difference plate 33 changes the polarization state of the laser light L1, and the condenser lens 34 condenses the laser light L1 as the excitation light EL in the irradiated body 41 and substantially reduces the fluorescence FL from the irradiated body 41. Take out as parallel rays. The light irradiation plate 35 is a phosphor wheel having an irradiated body 41 that generates fluorescence FL from the excitation light EL and reflects the excitation light EL. The fly-eye optical system 36 equalizes the intensity of the illumination light L3 of the laser light L1, the light source light L2, and the fluorescence FL emitted from the polarization dichroic mirror 32, and the polarization conversion unit 37 is emitted from the polarization dichroic mirror 32. The field lens 38 adjusts the incident angle of the illumination light L3 to the reflective liquid crystal element 23 by aligning the polarization direction of the illumination light L3.

The polarization beam splitter (PBS) 22 is a beam splitter that branches an optical path according to the polarization direction. The polarization beam splitter 22 is obtained by bonding a pair of right-angle prisms. On the bonding surface, the illumination light L3 that is linearly polarized light in a predetermined direction incident from the light source device 21 is selected on the inclined surface of one right-angle prism. A polarization separation surface 22a made of a polarization separation film that reflects light is formed. Thereby, the illumination light L3 emitted from the light source device 21 can be reflected and incident on a reflective liquid crystal element 23 described later. Further, the image light L 4 reflected by the reflective liquid crystal element 23 can be transmitted and incident on the projection optical system 26. The polarization separation surface 22a reflects S-polarized light based on this and transmits P-polarized light.

The reflective liquid crystal element 23 is a display panel that forms the image light L4, that is, an image display element, and particularly a light valve or a spatial light in that the image light L4 is formed from the illumination light L3 by changing the spatial reflectance. It can be said that it is a modulation element. The reflective liquid crystal element (image display element) 23 includes an image display panel that is a plate-like electronic component. The reflection type liquid crystal element 23 is a micro display also called LCOS (liquid crystal on silicon), in which a circuit is directly formed on the surface of a silicon chip and a liquid crystal layer is sandwiched between a counter substrate. When a voltage corresponding to a drive signal is applied to the liquid crystal layer for each pixel, the reflective liquid crystal element 23 modulates the illumination light L3 by changing the arrangement of liquid crystal molecules, and displays a desired image by reflection. Is. At this time, when S-polarized light with the polarization separation surface 22a as a reference is incident on the reflective liquid crystal element 23 as illumination light L3, P-polarized light with the polarization separation surface 22a as a reference is reflected as video light L4.

Although the detailed description is omitted, the projection optical system 26 enlarges and projects an image obtained from the reflective liquid crystal element 23 that is an image display element onto a screen or other projection target (not shown). The projection optical system 26 includes a plurality of lens groups and / or reflecting surfaces, and focusing and zooming can be performed by moving some lens groups in the direction of the optical axis SX.

The video drive circuit 25 operates or interlocks the drive unit 39 of the reflective liquid crystal element 23 and the light irradiation plate 35 based on video signals input from various content sources (not shown) including terminal devices such as computers. It is a circuit part to do. The video drive circuit 25 operates based on a control signal from the control circuit 28, and outputs a drive signal corresponding to the video signal to the reflective liquid crystal element 23 to perform an image display operation. At this time, the video drive circuit 25 monitors the rotational position of the light irradiation plate 35 via the control circuit 28, and controls the light emission operation of the laser array 51 and the LED array 151 corresponding to the rotation of the light irradiation plate 35. However, the display operation of the reflective liquid crystal element 23 is synchronized with the sequentially emitted blue light, green light, and red light, and the reflective liquid crystal element 23 performs the display operation of each color.

Hereinafter, the components, functions, operations, and the like of the light source device 21 will be described. First, the first beam forming unit 31 includes a laser array 51, a collimator array 52, and a beam reduction lens 53. Here, the laser array 51 is an individual light source, and is an excitation light source for the phosphor layer 71 (see FIG. 3B) incorporated in the irradiated body 41 and also an illumination light source for blue. The laser array (excitation light source) 51 is configured by two-dimensionally arranging laser diodes (hereinafter also referred to as LDs) that emit blue laser light L1 as excitation light EL, and has a uniform polarization direction. Emit light. The laser beam L1 emits P-polarized light with the polarization dichroic mirror 32 as a reference. The collimator array 52 includes a number of lens elements corresponding to the number of LDs constituting the laser array 51. The collimator array 52 converts the laser light L1 emitted from each LD constituting the laser array 51 into a substantially parallel light beam. The beam reduction lens 53 is an afocal system in which a positive lens and a negative lens are combined, and the laser beam L1 is left as a substantially parallel beam, the beam diameter is decreased, and the excitation beam EL having a desired cross-sectional area is obtained. The beam contraction lens 53 is for narrowing the beam diameter relatively small, and has a central rectangular area having sides set to about a fraction of one side of the polarization dichroic mirror 32 or a central circular area having the same size diameter. In addition, the beam diameter of the excitation light EL is reduced. That is, the beam diameter of the blue laser light L1 is about a fraction of the beam diameter of the red light source light L2 described later. Since the blue laser light L1 only needs to have a small beam diameter at the entrance pupil of the condenser lens 34, which will be described later, the laser light propagating to the condenser lens 34 can be obtained by giving the beam reducing lens 53 positive power. You may make it converge gradually. In this case, a single beam reduction lens can be configured.

The second beam forming unit 131 includes an LED array 151, a collimator array 52, and a beam reduction lens 153. Here, the LED array 151 is configured by two-dimensionally arranging LEDs that emit the red light source light L2. The LED array 151 may be an LED having a large light emission area instead of the array. Further, the second beam forming unit 131 can emit P-polarized light or S-polarized light with the polarization dichroic mirror 32 as a reference as the light source light L2 by incorporating a polarization conversion unit or replacing it with an LD. The collimator array 52 includes a large number of lens elements corresponding to the large number of LEDs constituting the LED array 151, and the light source light L2 emitted from each LED is set as a substantially parallel light beam. The beam reduction lens 153 changes the light source light L2 into a substantially parallel light beam.

The polarization dichroic mirror 32 is disposed between the beam forming unit 31 including the excitation light source and the light irradiation plate 35, and corresponds to a beam splitter that branches fluorescence from the optical path of the excitation light. More specifically, the polarization dichroic mirror 32 functions as a polarization separation mirror that transmits P-polarized light and selectively reflects S-polarized light, and green light that transmits blue light and red light and has a wavelength therebetween. A dichroic mirror that selectively reflects light. The polarization dichroic mirror 32 is formed by forming a dielectric multilayer film 32a on one side of a parallel plate, and transmits the blue excitation light EL from the beam forming unit 31 and the red light source light L2 from the beam forming unit 131 as they are. In addition, blue light and green light from the irradiated body 41 side are reflected and reflected to the field lens 38 side. In other words, the polarization dichroic mirror 32 branches blue light, which is polarized light in a specific direction, on the optical path depending on transmission and reflection. Further, the polarization beam splitter 22 can prevent the fluorescence FL from returning to the first beam forming unit 31 that is an excitation light source and guide it to a desired optical path. Specifically, the polarization dichroic mirror 32 transmits the excitation light EL that is P-polarized light, and is used in combination with the phase difference plate 33 so that it is not utilized for excitation from the irradiated body 41 side and remains in the blue light. The reflected S-polarized light is reflected and guided to the polarization conversion unit 37 in the optical path of the fluorescence FL. Further, the polarization dichroic mirror 32 reflects the green light, that is, the fluorescence FL, which is illuminated with the excitation light EL and is generated by the irradiated body 41, and guides it to the polarization conversion unit 37. As described above, the blue light obtained from the laser array 51 as the excitation light source can be used without waste.

The retardation film 33 is a quarter wave plate made of a birefringent material. The phase difference plate 33 transmits the P-polarized excitation light EL that has passed through the polarization dichroic mirror 32 according to the arrangement, and changes the P-polarized light to circularly-polarized light. Further, the phase difference plate 33 transmits the blue light that has returned from the irradiated object 41 side, that is, the excitation light EL, and changes from circularly polarized light to S-polarized light. As a result, the blue light, that is, the excitation light EL that has returned from the irradiated object 41 side through the phase difference plate 33 is almost reflected by the polarization dichroic mirror 32 and efficiently guided to the polarization conversion unit 37.

The condenser lens 34 guides the laser beam L1 that has passed through the polarization dichroic mirror 32 to the phosphor layer 71 so as to be focused on the phosphor layer 71 (see FIG. 3B) of the irradiated body 41 as excitation light EL. The incident angle of the excitation light EL incident on the light irradiation plate 35 can be adjusted by the condenser lens 34. The condenser lens 34 collects the green light generated from the irradiated object 41, that is, the fluorescence FL, and guides it to the polarization dichroic mirror 32. The condenser lens 34 also has a role of collecting excitation light EL, that is, blue light reflected by a scattering reflecting surface, which will be described later, provided separately from the phosphor layer 71 in the irradiated object 41 and guiding it to the polarization dichroic mirror 32. Note that the condenser lens 34 is not limited to a single lens, and may be configured with a plurality of lenses.

As shown in FIG. 2, the excitation light EL is incident only on the central region of the entrance pupil of the condenser lens 34 with the beam diameter being relatively reduced by the beam reduction lens 53 shown in FIG. The incident angle θ of the excitation light EL having passed through the light irradiation plate 35 to the irradiated object 41 is relative to the normal direction (optical axis SX direction) of the irradiated object 41 or the phosphor layer 71 (see FIG. 3B). The maximum is 20 °, that is, 20 ° or less. On the other hand, since the entire condenser lens 34 can be used for the fluorescence FL from the irradiated body 41 of the light irradiation plate 35, the emission angle θ ′ of the fluorescent FL from the irradiated body 41 is the normal direction of the irradiated body 41. It is 20 ° to 50 ° or less with respect to (optical axis SX direction). That is, the opening angle of the excitation light EL that is incident on the irradiated object 41 by the condenser lens 34 is sufficiently smaller than the opening angle of the fluorescence FL from the irradiated object 41 that is taken in by the condenser lens 34, and is imbalanced between the forward path and the return path. How to use

As shown in FIG. 3A, the light irradiation plate 35 is obtained by fixing an annular irradiated body 41 on a disk-shaped substrate 35a, and is driven by a drive unit 39 shown in FIG. 1 around an axis RX. Rotates at a constant speed. The irradiated body 41 includes a first area AR1 that generates fluorescence when irradiated with the excitation light EL, and a second area AR2 that is a scattering surface that reflects the excitation light EL while being slightly scattered. In the first region AR1 of the irradiation object 41, fluorescence FL having a longer wavelength is generated by absorption of the excitation light EL. That is, in the first area AR1, the green fluorescent light FL is emitted from the light incident area IA where the blue excitation light EL is incident locally toward the condenser lens 34 shown in FIG. Further, from the second area AR2, the blue light is reflected while being slightly scattered and is emitted toward the condenser lens 34 shown in FIG. In the second region AR2, it is desirable not to change the polarization state so much.

The light emission of the laser array 51 and the LED array 151 is controlled by the control circuit 28 as follows, for example. As shown in FIG. 3A, the position facing the condenser lens 34, that is, the light incident area IA is an area from the middle of the first area AR1 to the middle of the second area AR2 (in the range from 1 o'clock to 5 o'clock in the figure). In the case of being arranged in the 1/3 area indicated by the symbol R), the red light source light L2 is emitted from the LED array 151, and other areas (corresponding to the range from 5 o'clock to 1 o'clock in the figure) In the region 2/3 indicated by reference character B), the blue laser light L1 is emitted from the laser array 51.

By controlling in this way, it is possible to guide the blue, green and red luminous fluxes to the field lens 38 in time series. More specifically, in a state where the blue laser light L1 irradiates the second area AR2 (except for the area indicated by the symbol R in FIG. 3A), the blue light is guided to the field lens 38, and the blue laser light is emitted. In a state where L1 irradiates the first area AR1 (excluding the area indicated by the symbol R in FIG. 3A), the green light is guided to the field lens 38. The red light source light L2 from the LED array 151 is guided to the field lens 38 as red light from an optical path unrelated to the light irradiation plate 35 at a timing different from that of blue light or green light. As a result, when the light irradiation plate 35 rotates, for example, in the clockwise direction, the illumination light L3 is emitted from the light source device 21 in the order of green, blue, and red.

Note that the light emission control is not limited to this, and the blue laser light L1 is emitted from the laser array 51 during one rotation of the irradiated object 41, and the red light source light L2 is emitted from the LED array 151 during the next one rotation. May be injected.

As shown in FIG. 3B, the irradiated body 41 has a flat phosphor layer 71 in the center in the first region AR1 shown in FIG. 3A, and sandwiches the phosphor layer 71 from the excitation light source side and the counter excitation light source side. Thus, it has a pair of light transmission layers 72 and 73. On the outside of these light transmission layers 72 and 73, a surface uneven structure 75 and a reflective layer 76 are provided. The light transmission layer 72 and the surface concavo-convex structure 75 may be integrally formed.

The phosphor layer 71 is a thin flat layer and extends in a flat plate shape along a plane perpendicular to the optical axis SX. The phosphor layer 71 is composed of phosphor particles and a binder material that fixes the phosphor particles. The phosphor particles constituting the phosphor layer 71 are phosphors capable of emitting fluorescence having a peak wavelength from 500 nm to 560 nm, for example, as green wavelength light when light having a wavelength corresponding to the excitation light EL is incident. . Specifically, as phosphor particles constituting the phosphor layer 71, cerium activated yttrium aluminum garnet (YAG: Ce) (a typical chemical structure of the crystal matrix of this phosphor is Y ₃ (Al, Ga) ₃ O ₁₂ ), cerium activated lutetium aluminum garnet (LuAG: Ce), β sialon phosphor, or the like can be used.

The surface concavo-convex structure 75 has an array of concavo-convex portions and is an aggregate of a plurality of minute optical elements 75a having the same shape. Each optical element 75a constituting the surface concavo-convex structure 75 has, for example, a quadrangular pyramid shape as shown in FIG. 4A, and has a condensing effect on the excitation light EL incident on the surface 75s that is an inclined surface. Here, the angle α between the bottom surface and the inclined surface of the optical element 75a is related to the arrangement of the phosphor layer 71, but is set to about 35 ° to 55 °. The optical element 75a may be a triangular pyramid as shown in FIG. 4B, a cone as shown in FIG. 4C, or a convex lens shape as shown in FIG. 4D. In the case of a cone, the apex angle is preferably set to 70 to 110 °. With these shapes, it becomes easy to disperse the excitation light EL in the phosphor layer 71 to form an array-shaped light emitting region.

The uneven surface structure 75 is formed of a light-transmitting material, specifically, a material such as polycarbonate resin, methacrylic resin, cycloolefin resin, or a material obtained by appropriately adding auxiliary additives thereto. However, the surface concavo-convex structure 75 is formed of a material that does not include a phosphor. Thereby, it is possible to prevent the formation of fluorescence in the uneven surface structure 75, and it becomes easy to limit the emission angle of the fluorescence extracted from the light irradiation plate 35 to a narrow range.

As shown in FIG. 4A, when the optical element 75a has a quadrangular pyramid shape, the optical elements 75a are arranged in a two-dimensional pattern in a lattice shape, reducing the loss and improving the light utilization efficiency. When the optical elements 75a are triangular pyramids as shown in FIG. 4B, two-dimensionally densely arranged, and in the case of a cone as shown in FIG. 4C, a part of the conical surface which is the surface 75s is cut out to form a rectangular region. Are arranged to fit in However, a gap may be formed between the outer edges of the surfaces 75s such as adjacent cones. In this case, the light transmission layer 72 is exposed from the gap between the optical elements 75a.

As shown in FIGS. 3B and 5, the pair of light transmission layers 72 and 73 sandwiching the phosphor layer 71 are flat layers having light transmission lines, and can transmit the excitation light EL and the like with low loss. . The light transmission layer 72 and the surface concavo-convex structure 75 can be obtained by, for example, forming them integrally, but can also be obtained by forming and bonding them separately. The light transmission layer 72 on the excitation light source side is sandwiched between the surface uneven structure 75 and the phosphor layer 71 to adjust the distance between the surface uneven structure 75 and the phosphor layer 71. It has a role to adjust the light state. The other light transmission layer 73 is sandwiched between the reflection layer 76 and the phosphor layer 71 to adjust the distance from the irradiation region LA, which is the light emission region of the phosphor layer 71, to the reflection layer 76. The light transmitting layers 72 and 73 are formed of a material that has high light transmittance and does not include a phosphor, similarly to the surface uneven structure 75. Specifically, the light transmission layers 72 and 73 can be formed of the same material as the surface uneven structure 75.

The innermost reflection layer 76 is a thin flat layer and extends in a flat plate shape along a plane perpendicular to the optical axis SX. The reflection layer 76 is disposed on the opposite side of the surface uneven structure 75 with the phosphor layer 71 interposed therebetween, and the excitation light EL that has passed through the phosphor layer 71 and the fluorescence FL that is directed toward the reflection layer 76 are transmitted to the phosphor layer 71 side or It has a role of returning to the LED array 151 side. That is, the reflective surface 76s, which is the surface of the reflective layer 76, exhibits a high reflectance in the wavelength range of the excitation light EL and the fluorescence FL.

With reference to FIG. 5, the optical path and propagation of the excitation light EL incident on the irradiated object 41 and the fluorescence FL generated thereby will be described. FIG. 5 shows the light incident area IA shown in FIG. 3A.

The excitation light EL is incident on the irradiated body 41 at an incident angle of 20 ° or less, and the opening angle of the excitation light EL is relatively small. The excitation light EL incident on the surface concavo-convex structure 75 of the irradiated body 41 is refracted by the inclined surface 75 s and enters the phosphor layer 71. At this time, the excitation light EL incident on the irradiated object 41 is incident on a local irradiation region (light emitting region) LA in the phosphor layer 71 because the incident angle is small. Such an irradiation area LA exists opposite to each optical element 75a, and is two-dimensionally arranged in a lattice pattern corresponding to each optical element 75a along the phosphor layer 71. That is, a lattice-like gap GA is formed between adjacent irradiation areas LA, and excitation light EL hardly enters the gap GA. In this way, a plurality of irradiation areas LA arranged two-dimensionally in a grid pattern can be arranged or set.

Further, in the illustrated phosphor layer 71, since the excitation light EL is incident on a relatively narrow irradiation region (light emitting region) LA in which the light is dispersed, the light emitting area is reduced accordingly. In addition, by narrowing the irradiation area LA, it is easy to align the conditions for the fluorescence FL emitted from the irradiation area LA to the surface side to be incident again on the same optical element 75a, and refraction of positive power when passing through the optical element 75a. In response, the emission angle of the fluorescence FL emitted from the irradiated body 41 becomes relatively small. As a result, the etendue of the fluorescent light FL among the illumination light L3 emitted from the light source device 21 through the condenser lens 34 or the like can be reliably reduced, and the use efficiency of the fluorescent light FL, that is, the illumination light L3 by the reflective liquid crystal element 23 can be reduced. Can be easily increased.

In addition, 2nd area | region AR2 of the light irradiation board 35 shown to FIG. 3A is a mirror corresponding to excitation light EL. Also in the second region AR2, the surface uneven structure 75 of the irradiated object 41 provided in the first region AR1 can be provided, and the diffuser layer 79 can be arranged instead of the phosphor layer 71 (FIG. 3C). reference). In this case, the light distribution of the blue illumination component corresponding to the excitation light EL can be brought close to the light distribution of the fluorescence FL. The diffuser layer 79 is formed, for example, by dispersing dielectric powder having a refractive index different from that of the surroundings.

Referring back to FIG. 1, the fly-eye optical system 36 is disposed on the polarization beam splitter 22 side of the polarization dichroic mirror 32, and includes a first fly-eye lens 36a and a second fly-eye lens 36b. The first fly-eye lens 36a includes a plurality of lenses as elements for dividing the illumination light L3 including the laser light L1, the light source light L2, and the fluorescence FL, and the second fly-eye lens 36b moderately applies the illumination light L3. A plurality of lenses are included as an element for diverging.

The polarization conversion unit 37 is a combination of a plurality of conversion units including, for example, a polarization beam splitter and a wavelength plate, and is P-polarized light among S-polarized light and P-polarized light included in the green fluorescent light FL reflected by the polarization dichroic mirror 32. Are selectively converted to S-polarized light. The polarization conversion unit 37 selectively converts only P-polarized light included in the red light source light L2 that has passed through the polarization dichroic mirror 32 into S-polarized light. As a result, most of the illumination light L3 that has passed through the polarization conversion unit 37 is composed of S-polarized light components. Thereby, the substantially S-polarized fluorescence FL and the light source light L2 can be made incident on the polarization beam splitter 22, and the loss of the light source light is reduced. Note that the blue light (reflected excitation light) obtained from the excitation light EL is only the S-polarized light component reflected by the polarization dichroic mirror 32 and passes through the polarization conversion unit 37 almost as it is.

The field lens 38 has a function of uniformly superimposing the illumination light L3 on the reflective liquid crystal element 23 to make the incident angle range of the illumination light L3 uniform.

The outline of the operation of the projection device 2 shown in FIG. 1 will be described. The light source device 21 can form blue laser light L1, red light source light L2, and green fluorescence FL. As described above, the blue laser light L1, the green fluorescence FL, and the red light source light L2 are each emitted to the fly-eye optical system 36 side in a predetermined order. The reflective liquid crystal element 23 is illuminated in time series by each of the blue laser light L1, the red light source light L2, and the green fluorescent light FL from the light source device 21, and an image display corresponding to each color is made. Video light L 4 corresponding to each color image is emitted as reflected light, transmitted through the polarization beam splitter 22, and projected by the projection optical system 26. Since each color image projected in time series is switched and displayed at a high speed, these are superimposed on a human being and recognized as a color image.

According to the light source device 21 of the first embodiment described above, the surface uneven structure 75 having arrayed unevenness is formed on the surface of the light irradiation plate 35 on which the excitation light EL is incident. By condensing the light EL on the phosphor layer 71 while dispersing the light EL, it is possible to form an irradiation region LA which is an arrayed light emitting region. Further, when the excitation light EL is condensed on the phosphor layer 71, the incident angle of the excitation light EL with respect to the irradiated body 41 is set to 20 ° or less with respect to the normal direction of the phosphor layer 71, thereby Since the size of the light emitting region can be reduced and the angle range when the fluorescent light FL emits the light irradiation plate 35 can be made relatively narrow, the etendue can be reliably reduced while preventing an increase in size and an increase in light loss. .

[Second Embodiment]
The light source device according to the second embodiment will be described below. The light source device according to the second embodiment is a modification of the light source device according to the first embodiment, and matters not specifically described are the same as those in the first embodiment.

As shown in FIG. 6, the light source device 21 of the second embodiment incorporates a transmissive light irradiation plate (phosphor wheel) 135. As a result, the rear surface side of the light irradiation plate 135 becomes a light emission surface, and an emission-side condenser lens 134 is provided in front of the light-irradiation plate 135 in addition to the incident-side condenser lens 34. Subsequent to the condenser lens 134, a fly-eye optical system 36, a polarization conversion unit 37, and a field lens 38 are sequentially arranged. A second beam forming unit 131 is disposed between the condenser lens 134 and the fly-eye optical system 36. Here, the first beam forming unit 31 or the light irradiation plate 135 is for blue and green, and the second beam forming unit 131 is for red.

In the case of the present embodiment, the excitation light EL generated by the light irradiation plate 135 is not moved backward to the condenser lens 34 side, so that the phase difference plate 33 in FIG. 1 is unnecessary and is omitted, and the polarization dichroic mirror in FIG. Instead of 32, a dichroic mirror 132 that does not depend on polarization is used.

As shown in FIG. 7A, the irradiated object 41 provided on the light irradiation plate 135 is a transmission type phosphor wheel that emits fluorescence FL or the like to the opposite side of the laser array 51 that is a solid state light source. The first area AR1 that generates the fluorescence FL by irradiation and the second area AR2 that selectively transmits the excitation light EL while being slightly scattered are provided.

The irradiated body 41 has a structure that is integrated with the substrate 35a and embedded in the substrate 35a.
As shown in FIG. 7B, the first region AR1 of the irradiated object 41 has a phosphor layer 71 extending perpendicularly to the optical axis SX, a light transmission layer 72, and a dichroic mirror 78 in the center of the substrate 35a or the excitation light source side. And the surface uneven structure 75 are sequentially stacked, and the light transmission layer 172 and the opposing uneven structure 175 are sequentially stacked on the counter-excitation light source side of the substrate 35a. Of these, the surface uneven structure 75, the phosphor layer 71, the light transmission layer 72, and the light transmission layer 172 have the same functions as those in the first embodiment, and the description thereof is omitted.

The dichroic mirror 78 is a layer formed of a dielectric multilayer film. The dichroic mirror 78 is disposed between the surface uneven structure 75 and the phosphor layer 71 and transmits the blue excitation light EL. The formed fluorescence FL is reflected and emitted to the opposing uneven structure 175 side. The opposing concavo-convex structure 175 is provided on the surface on the opposite side of the surface concavo-convex structure 75 and has an array of concavo-convex shapes corresponding to the array concavo-convex of the surface concavo-convex structure 75. That is, the optical element 75a of the surface concavo-convex structure 75 and the optical element 175a of the counter concavo-convex structure 175 have substantially the same shape and are arranged to face each other with a separation in the optical axis SX direction. As a result, in the surface uneven structure 75, the vertex of the optical element 75a is disposed on the lattice point, and in the opposing uneven structure 175, the vertex of the optical element 175a is disposed on the lattice point, and these

optical elements

75a and 175a have the same pitch. It is arranged without deviation.

The excitation light EL that has passed through the condenser lens 34 is incident on the irradiated object 41 at an incident angle of 20 ° or less, and the aperture angle is small. The excitation light EL incident on the surface uneven structure 75 of the irradiated body 41 is irradiated with a relatively narrow irradiation region (light emitting region) LA arranged in a lattice pattern in the phosphor layer 71 by the optical element 75a constituting the surface uneven structure 75. Is incident on. As described above, the emission area also decreases as the excitation light EL enters the relatively narrow irradiation area (light emission area) LA in which the excitation light EL is dispersed. Furthermore, by narrowing the irradiation region (light emitting region) LA, it is easy to align the conditions for the fluorescence FL from the irradiation region (light emitting region) LA to enter the optical element 175a of the opposing concavo-convex structure 175, and pass through the optical element 175a. The emission angle of the fluorescence FL emitted from the irradiated body 41 is relatively small. As a result, the etendue can be reliably reduced with respect to the fluorescence FL among the illumination light L3 emitted from the light source device 21 through the condenser lens 134 and the like, and the use efficiency of the fluorescence FL, that is, the illumination light L3 by the reflective liquid crystal element 23 can be reduced. Can be easily increased.

The second area AR2 of the light irradiation plate 135 has a structure that diffuses and transmits the excitation light EL. Also in the second area AR2, the surface uneven structure 75 of the irradiated body 41 provided in the first area AR1 can be provided, and a diffuser layer can be arranged instead of the phosphor. In this case, the light distribution of the blue illumination component corresponding to the excitation light EL can be brought close to the light distribution of the fluorescence FL. The diffuser layer is formed, for example, by dispersing dielectric powder having a refractive index different from that of the surroundings.

The light source device according to the embodiment has been described above, but the light source device according to the present invention is not limited to the above. For example, the specific configurations of the light source device 21, the projection optical system 26, and the like are not limited to those shown in the drawings, and can be changed as appropriate according to the application.

Also, a digital micromirror device (DMD) can be used in place of the reflective liquid crystal element 23. In this case, instead of the polarization beam splitter 22, a prism that guides illumination light to the DMD and guides the reflected light from the DMD to the projection optical system 26 may be disposed.

In the beam forming unit 31, an LED array can be used instead of the laser array 51. However, in the embodiment of FIG. 1, the polarization direction of light from the LED array can be aligned before entering the polarization dichroic mirror 32. desirable.

As the image display element, a transmissive liquid crystal element may be used instead of the reflective liquid crystal element 23.

The excitation light EL incident on the light irradiation plate (phosphor wheel) 35 is not limited to visible light but can be ultraviolet light or the like. In this case, the irradiated object 41 generates blue light and green light. What is necessary is just to comprise. Further, it is not always necessary to irradiate the irradiated object 41 with all the light beams of the excitation light at an incident angle of 20 ° or less, and the main light beam of the excitation light (light having a light amount of 80 to 90% or more of the light source light) is 20 If the incident angle is within an angle of less than 0 °, the size of the array-like light emitting region can be sufficiently reduced, and the angle range when the fluorescence exits the light irradiation plate can be narrowed.

The light incident on the image display element can be prevented from being time-shared. In that case, the irradiated object 41 provided on the light irradiation plate 135 is not particularly divided into regions. That is, the irradiated object 41 is configured only by the first region AR1 that generates the fluorescence FL. At this time, the first region AR1 absorbs a part of the excitation light and emits fluorescence, and at the same time, diffuses a part of the excitation light and reflects in the case of the first embodiment, and in the case of the second embodiment. Make it transparent. At this time, there may or may not be a drive device for rotating the wheel. In this case, the laser array 51 and the LED array 151 may be simultaneously driven to make the illumination light L3 white, and the reflective liquid crystal element 23 may be a type in which a color filter is provided for each pixel.

4A and 4B, the optical element 75a having a polygonal pyramid shape may have a shape obtained by cutting the top, that is, a polygonal frustum or a truncated pyramid. Also, the conical optical element 75a as shown in FIG. 4C can also have a shape with the top cut off, that is, a truncated cone or truncated cone.

Further, the optical element 75a constituting the surface uneven structure 75 and the optical element 175a constituting the opposing uneven structure 175 do not have to have the same shape, and, for example, a pyramid and a cone are arranged so as to face each other in the optical axis direction. These vertices are preferably arranged on the same straight line parallel to the optical axis direction.

Claims

An excitation light source that emits excitation light;
A light irradiation plate having a phosphor layer that emits fluorescence when irradiated with excitation light, and
Of the light irradiation plate, a surface uneven structure having an array of unevenness is formed on the surface on which excitation light is incident,
A light source device for a projection device, wherein an incident angle of excitation light to the light irradiation plate is 20 ° or less with respect to a normal direction of the phosphor layer.
2. The light source device for a projection device according to claim 1, wherein the light irradiation plate has a reflective surface on the opposite side of the surface uneven structure through the phosphor layer.
The light irradiation plate has an opposing concavo-convex structure having an array of concavo-convex shapes corresponding to the array concavo-convex of the surface concavo-convex structure on the surface opposite to the surface concavo-convex structure via the phosphor layer. The light source device for a projection device according to claim 1, further comprising a layer that transmits excitation light and reflects fluorescence between the surface uneven structure and the phosphor layer.
The light irradiation plate has a flat light transmission layer formed of a material not containing a phosphor between the phosphor layer and the surface uneven structure. Light source device for the projection apparatus.
The light source device for a projection device according to any one of claims 1 to 4, wherein the uneven surface structure is formed of a material that does not include a phosphor.
The light source device for a projection device according to any one of claims 1 to 5, wherein the surface uneven structure is a polygonal pyramid, a cone, a convex lens shape, or a shape obtained by cutting a top portion thereof.
The light source device for a projection device according to any one of claims 1 to 6, further comprising a condenser lens adjacent to the excitation light source side of the light irradiation plate for guiding excitation light to the phosphor layer.
3. The light source device for a projection device according to claim 1, further comprising a beam splitter disposed between the excitation light source and the light irradiation plate and branching fluorescence from an optical path of the excitation light.
The excitation light source emits blue light as excitation light, and the phosphor layer emits fluorescence generated by excitation with blue light,
The beam splitter is a polarization dichroic mirror that is used in combination with a phase difference plate and splits blue light, which is polarized light in a specific direction, on the optical path depending on whether it is transmitted or reflected, and converts the blue light from the excitation light source into the fluorescent light. 9. The light source device for a projection device according to claim 8, wherein the light source device guides blue light that has not been used for excitation in the phosphor layer to a fluorescent light path while guiding the light to a body.
A light source device according to any one of claims 1 to 9,
A projection apparatus comprising: an image display element illuminated by the light source device; and a projection optical system that projects an image formed by the image display element.