JP2015049442A - Polarization separation element, illumination device, and projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarization separation element which has a high yield and is capable of obtaining desired optical characteristics and to provide an illumination device and a projector.SOLUTION: The polarization separation element includes a base material having a first surface and a second surface facing the first surface, a first optical element provided on the side of the first surface of the base material, mainly reflecting light in a first wavelength region polarized in a first direction, and mainly transmitting light in a second wavelength region different from the light in the first wavelength region, polarized in a second direction orthogonal to the first direction, and a second optical element provided on the side of the second surface of the base material, mainly reflecting the light in the second wavelength region polarized in the first direction, and mainly transmitting the light in the second wavelength region polarized in the second direction.

Description

  The present invention relates to a polarization separation element, an illumination device, and a projector.

  Conventionally, a polarization separation element using a dielectric multilayer film is known (for example, see Patent Document 1 below). This dielectric multilayer film is designed to satisfy the required specifications.

JP 2009-132989 A

  However, in the above prior art, since it is difficult to set the polarization separation characteristics finely with respect to the wavelength, there is a problem that desired optical characteristics cannot be obtained and the yield is lowered.

  One aspect of the present invention is made to solve the above-described problems, and provides a polarization separation element, an illumination device, and a projector that have high yield and can obtain desired optical characteristics. With the goal.

  According to the first aspect of the present invention, a base material having a first surface and a second surface facing the first surface, provided on the first surface side of the base material, The first wavelength band light mainly polarized in the first direction is reflected, and the second wavelength band light is different from the first wavelength band light polarized in the second direction orthogonal to the first direction. The first optical element that mainly transmits light; the second optical element that is provided on the second surface side of the substrate and that is polarized in the first direction mainly reflects; And a second optical element that mainly transmits the light in the second wavelength band polarized in the direction.

  According to the polarization separation element according to the first aspect, the first optical element is provided on the first surface side of the base material, and the second optical element is provided on the second surface side of the base material. Functions can be distributed. Accordingly, the first optical element and the second optical element can be designed easily and reliably because the design conditions of the respective optical characteristics are relaxed and the design is facilitated. It becomes possible. Therefore, the cost can be reduced by improving the yield.

In the first aspect, the first optical element and the second optical element may be configured to mainly transmit light in the third wavelength range.
According to this configuration, the light in the third wavelength region can be taken out and used effectively.

In the first aspect described above, the first prism provided to sandwich the first optical element between the substrate and the second optical element sandwiched between the substrate and the first prism. The second prism may be further provided.
According to this configuration, a prism-type polarizing beam splitter can be provided by sandwiching the base material by the first prism and the second prism.

  According to the second aspect of the present invention, the polarization separation element according to the first aspect and a first light that is provided on the first optical element side of the polarization separation element and emits light in the first wavelength range. A light source, a second light source that is provided on the first optical element side of the polarization separation element and emits light in the second wavelength band, and the first light element reflected by the first optical element. A phosphor layer that emits light in the third wavelength range and an optical path of light in the second wavelength range that has passed through the polarization separation element, and is incident And a polarization conversion device that converts the polarization direction of the emitted light from the second direction to the first direction and emits the light so as to be incident on the second optical element.

  According to the configuration of the illumination device according to the second aspect, since the polarization separation element is provided, the light in the first wavelength range emitted from the first light source is guided well to the phosphor layer and emitted from the polarization conversion device. The light in the second wavelength band polarized in the first direction can be favorably reflected. Therefore, when the light in the third wavelength range emitted from the phosphor layer passes through, for example, the polarization separation element, the light in the second wavelength range and the light in the third wavelength range are converted into the second wavelength of the base material. Can be efficiently injected to the surface side. Therefore, a highly reliable lighting device that can obtain desired optical characteristics at low cost is provided.

In the second aspect, the polarization conversion device may include a first reflection element that reflects light in the second wavelength band and a retardation plate.
According to this configuration, for example, the polarization direction of the light in the second wavelength band is easily and reliably converted from the second direction to the first direction by transmitting the retardation plate made of a λ / 4 plate twice. can do.

In the second aspect, the first reflecting element may be configured to diffusely reflect light in the second wavelength range.
According to this configuration, since the first reflective element diffuses and reflects the light in the second wavelength range, the light in the third wavelength range emitted from the phosphor layer indicates how to spread the light in the second wavelength range. It can be close to how it spreads.

In the second aspect, the light in the second wavelength range is incident on the reflective element as circularly polarized light, and the first reflective element has the rotation direction of the light in the second wavelength range reversed. It may be configured to emit as circularly polarized light.
According to this configuration, the polarization direction of the light in the second wavelength region when entering the second optical element can be surely set to the first direction.

The second aspect may further include a second reflecting element that reflects the light in the third wavelength range emitted from the phosphor layer so as to be incident on the polarization separation element.
According to this configuration, since the second reflective element is provided, light in the third wavelength band can be emitted toward the polarization separation element side.

  According to the third aspect of the present invention, an illumination device that emits illumination light, a light modulation device that forms image light by modulating the illumination light according to image information, and projection optics that projects the image light And a projector using the illumination device according to the first aspect as the illumination device.

  According to the configuration of the projector according to the third aspect, since the above-described illumination device is provided, the projector itself is also highly reliable with low cost and desired optical characteristics.

It is a top view which shows schematic structure of the projector which concerns on this embodiment. It is a top view which shows schematic structure of the illuminating device which concerns on this embodiment. It is a figure which shows the principal part structure of the polarizing beam splitter which concerns on this embodiment. (A), (b) is a figure which shows the characteristic of the polarization splitting film concerning this embodiment. It is a figure which shows schematic structure of the reflective element which concerns on this embodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of a polarization beam splitting element, an illumination device, and a projector according to the invention will be described with reference to the drawings.
In addition, in the drawings used in the following description, in order to make the features easy to understand, there are cases where the portions that become the features are enlarged for the sake of convenience, and the dimensional ratios of the respective components are not always the same as the actual ones. Absent.

A configuration of the projector according to the present embodiment will be described. FIG. 1 is a plan view showing a schematic configuration of a projector according to the present embodiment.
As shown in FIG. 1, the projector 1 is a projection type image display device that displays a color image (image) on a screen (projection surface) SCR. The projector 1 uses three light modulation devices corresponding to the respective color lights of red light LR, green light LG, and blue light LB. Further, the projector 1 uses a semiconductor laser (laser light source) that can obtain light with high luminance and high output as the light source of the illumination device.

  As shown in FIG. 1, the projector 1 includes an illumination device 2 that irradiates illumination light WL, and a color separation optical system 3 that separates the illumination light WL from the illumination device 2 into red light LR, green light LG, and blue light LB. A light modulation device 4R, a light modulation device 4G, and a light modulation device 4B that modulate the color lights LR, LG, and LB in accordance with the image information and form image light corresponding to the color lights LR, LG, and LB; A synthesis optical system 5 that synthesizes image light from the light modulation devices 4R, 4G, and 4B and a projection optical system 6 that projects the image light from the synthesis optical system 5 toward the screen SCR are roughly provided.

  The illumination device 2 mixes the fluorescent light (yellow light) emitted from the phosphor excited by the excitation light (blue light) emitted from the first light source and the blue light emitted from the second light source. Is used to obtain illumination light (white light) WL. The illumination device 2 irradiates the color separation optical system 3 with the illumination light WL adjusted to have a uniform illuminance distribution. The configuration of the illumination device 2 will be described later in detail.

  The color separation optical system 3 includes a first dichroic mirror 7a and a second dichroic mirror 7b, a first total reflection mirror 8a, a second total reflection mirror 8b, a third total reflection mirror 8c, and a first A relay lens 9a and a second relay lens 9b are roughly provided.

  Among these, the first dichroic mirror 7a has a function of separating the illumination light WL from the illumination device 2 into the red light LR and the other color lights LG and LB, and transmits the separated red light LR. The other color lights LG and LB are reflected. On the other hand, the second dichroic mirror 7b has a function of separating the other color lights LG and LB into the green light LG and the blue light LB, and reflects the separated green light LG and transmits the blue light LB. .

  The first total reflection mirror 8a is disposed in the optical path of the red light LR, and reflects the red light LR transmitted through the first dichroic mirror 7a toward the light modulation device 4R. On the other hand, the second total reflection mirror 8b and the third total reflection mirror 8c are arranged in the optical path of the blue light LB, and guide the blue light LB transmitted through the second dichroic mirror 7b to the light modulation device 4B. The green light LG is reflected from the second dichroic mirror 7b toward the light modulation device 4G.

  The first relay lens 9a and the second relay lens 9b are disposed downstream of the second dichroic mirror 7b in the optical path of the blue light LB. The first relay lens 9a and the second relay lens 9b have a function of compensating for the optical loss of the blue light LB due to the optical path length of the blue light LB being longer than the optical path lengths of the red light LR and the green light LG. doing.

  Each of the light modulation devices 4R, 4G, and 4B includes a liquid crystal panel, and includes polarizing plates (not shown) on the incident side and the emission side. Each of the light modulation devices 4R, 4G, and 4B forms image light by modulating each color light LR, LG, and LB according to image information.

  Further, on the incident surface side of each of the light modulation devices 4R, 4G, and 4B, a field lens 10R, a field lens 10G, and a field that collimate the respective color lights LR, LG, and LB incident on the light modulation devices 4R, 4G, and 4B. A lens 10B is disposed.

  The synthesizing optical system 5 is composed of a cross dichroic prism, synthesizes the image light incident from each of the light modulation devices 4R, 4G, and 4B, and emits the synthesized image light toward the projection optical system 6.

  The projection optical system 6 includes a projection lens group, and enlarges and projects the image light combined by the combining optical system 5 toward the screen SCR. Thereby, an enlarged color video (image) is displayed on the screen SCR.

(Lighting device)
Next, the configuration of the illumination device 2 used for the projector 1 will be described. FIG. 2 is a plan view showing a schematic configuration of the illumination device 2.

  As shown in FIG. 2, the illumination device 2 includes an array light source 21, a collimator optical system 22, an afocal optical system 23, a homogenizer optical system 24, a polarization beam splitter (polarization separation element) 25, and a pickup optical system. 27, a fluorescent light emitting element 28, a polarization conversion device 45, an integrator optical system 29, a polarization conversion element 30, and a superimposing optical system 31.

  The array light source 21 includes a first array light source (first light source) 21A in which a plurality of semiconductor lasers 21a are arranged in an array, and a second array light source (second light source) in which a plurality of semiconductor lasers 21b are arranged in an array. 21B. The optical axis of the array light source 21 is defined as an optical axis ax1. In FIG. 2, one semiconductor laser 21a and one semiconductor laser 21b are drawn for simplification.

In addition, an optical axis of light emitted from a fluorescent light emitting element 28 described later toward the color separation optical system 3 side is defined as an optical axis ax2. The optical axis ax1 and the optical axis ax2 are in the same plane and are orthogonal to each other. On the optical axis ax1, the array light source 21, the collimator optical system 22, the afocal optical system 23, the homogenizer optical system 24, the polarization beam splitter 25, and the polarization conversion device 45 are arranged in this order. ing.
On the other hand, on the optical axis ax2, the fluorescent light emitting element 28, the pickup optical system 27, the polarization beam splitter 25, the integrator optical system 29, the polarization conversion element 30, and the superimposing optical system 31 are arranged in this order. Has been placed.

  The semiconductor laser 21a emits excitation light BL1 having a peak wavelength (for example, 446 nm) in the wavelength range of 440 to 450 nm as light in the first wavelength range. The excitation light BL1 emitted from each semiconductor laser 21a is coherent linearly polarized light and is emitted toward the polarization beam splitter 25 in parallel with the optical axis ax1. In the array light source 21, the polarization direction of the excitation light BL1 emitted from the semiconductor laser 21a is matched with the polarization direction (first direction) of the polarization component (for example, S polarization component) reflected by the polarization beam splitter 25. Yes.

  The semiconductor laser 21b emits blue light BL2 having a peak wavelength (for example, 460 nm) in a wavelength range of 457 to 467 nm as light in the second wavelength range. The blue light BL2 emitted from each semiconductor laser 21b is coherent linearly polarized light and is emitted toward the polarization beam splitter 25 in parallel with the optical axis ax1. In the array light source 21, the polarization direction of the blue light BL2 emitted from the semiconductor laser 21b is made to coincide with the polarization direction (second direction) of the polarization component (for example, P polarization component) transmitted through the polarization beam splitter 25. .

  In this way, the excitation light BL1 and the blue light BL2 emitted from the array light source 21 are incident on the collimator optical system 22, respectively.

  The collimator optical system 22 has a plurality of collimator lenses 22a arranged in an array corresponding to the semiconductor lasers 21a and 21b. The collimator optical system 22 converts the excitation light BL1 and blue light BL2 emitted from the array light source 21 into parallel light. The excitation light BL1 and the blue light BL2 converted into parallel light by the collimator optical system 22 enter the afocal optical system 23.

  The afocal optical system 23 adjusts the sizes (spot diameters) of the excitation light BL1 and the blue light BL2. The afocal optical system 23 includes, for example, two afocal lenses 23a and afocal lenses 23b. Excitation light BL 1 and blue light BL 2 whose sizes are adjusted by passing through the afocal optical system 23 are incident on the homogenizer optical system 24.

  The homogenizer optical system 24 converts the light intensity distribution of the excitation light BL1 and the blue light BL2 into a uniform state (so-called top hat distribution), and includes, for example, a pair of multi-lens array 24a and multi-lens array 24b. Then, the excitation light BL 1 and the blue light BL 2 that have been converted to a uniform light intensity distribution by the homogenizer optical system 24 are incident on the polarization beam splitter 25.

  FIG. 3 is a diagram illustrating a main configuration of the polarization beam splitter 25. As shown in FIG. 3, the polarization beam splitter 25 includes a base 51, a first prism 52, a second prism 53, a first polarization separation film (first optical element) K <b> 1, 2 polarization separation films (second optical elements) K2. The first polarization separation film K <b> 1 is provided on the surface of the first prism 52 that faces the second prism 53. The second polarization separation film K <b> 2 is provided on the surface of the second prism 53 that faces the first prism 52. The first prism 52 is bonded to the second prism 53 by a base material 51 that functions as an adhesive. As a result, the first polarization separation film K1 is provided on the one surface (first surface) side of the substrate 51, and the second polarization separation film K2 is disposed on the other surface (second surface) side of the substrate 51. The provided configuration can be realized.

  The polarization beam splitter 25 is arranged such that the base material 51 forms an angle of 45 ° with respect to the optical axes ax1 and ax2. The polarization beam splitter 25 is disposed so that the intersection of the optical axes ax1 and ax2 orthogonal to each other coincides with the optical center of the substrate 51.

  The first polarization separation film K1 mainly reflects the light in the first wavelength range (excitation light BL1s) polarized in the first direction, and the light in the second wavelength range (blue light) polarized in the second direction. BL2p) is mainly transmitted. The first polarization separation film K1 has a function of mainly transmitting fluorescent light generated by the phosphor layer 32 described later.

  Here, the first polarization separation film K1 mainly reflects the excitation light BL1s in the first wavelength band polarized in the first direction. The light in the first wavelength band polarized in the first direction It means that the reflectance is higher than the reflectance of the light in the first wavelength band polarized in the second direction. Preferably, the reflectance of the excitation light BL1s is at least 90%.

  Further, the fact that the first polarization separation film K1 mainly transmits the light in the second wavelength band polarized in the second direction means that the transmittance of the light in the second wavelength band polarized in the second direction is high. It means that it is higher than the transmittance of the light in the second wavelength band polarized in the first direction. Preferably, the transmittance of the blue light BL2p is at least 90%.

  The fact that the first polarization separation film K1 mainly transmits the fluorescent light means that the transmittance of the fluorescent light is at least 90%.

  FIG. 4 is a diagram showing the polarization separation characteristics in the polarization beam splitter 25 according to the present embodiment, and FIG. 4A shows the polarization separation characteristics of the first polarization separation film K1, and FIG. Indicates the polarization separation characteristics of the second polarization separation film K2. 4A and 4B, the horizontal axis indicates the wavelength of light, and the vertical axis indicates the light transmittance.

  Specifically, in the present embodiment, as shown in FIG. 4A, the first polarization separation film K1 is light (excitation light) in the first wavelength region (440 to 450 nm) polarized in the first direction. BL1s) has a reflectance of, for example, 97% or more (that is, a transmittance of 3% or less), and transmits light (blue light BL2p) in the second wavelength region (457 to 467 nm) polarized in the second direction. The rate is, for example, 97% or more (that is, the reflectance is 3% or less). The first polarization separation film K1 has an average transmittance of light in the third wavelength range (fluorescent light YL), for example, 97% or more (that is, reflectance is 3% or less). Other wavelength regions are not particularly limited. In FIG. 4A, the lines indicating the excitation light BL1s, the blue light BL2p, and the fluorescent light YL are shifted so as not to overlap in order to make the drawing easy to see in the wavelength region of 500 nm or more.

  On the other hand, the second polarization separation film K2 mainly reflects the light in the second wavelength band polarized in the first direction and the light in the second wavelength band polarized in the second direction (blue light BL2p). Mainly transparent. Here, the light in the second wavelength band polarized in the first direction is S-polarized blue light BL2s emitted from the polarization conversion device 45 as described later. The second polarization separation film K2 has a function of mainly transmitting fluorescent light generated by the phosphor layer 32 described later.

  Here, the second polarization separation film K2 mainly reflects the light in the second wavelength band polarized in the first direction. The reflectance of the light in the second wavelength band polarized in the first direction. Is higher than the reflectance of the light in the second wavelength band polarized in the second direction. Preferably, the reflectance of the blue light BL2s is at least 90%.

  The second polarization separation film K2 mainly transmits the light in the second wavelength band polarized in the second direction. The transmittance of the light in the second wavelength band polarized in the second direction is It means that it is higher than the transmittance of the light in the second wavelength band polarized in the first direction. Preferably, the transmittance of the blue light BL2p is at least 90%.

  That the second polarization separation film K2 mainly transmits fluorescent light means that the transmittance of the fluorescent light is at least 90%.

  Specifically, in the present embodiment, as shown in FIG. 4B, the second polarization separation film K2 has a reflectance of light (blue light BL2s) in the second wavelength band polarized in the first direction. Is, for example, 97% or more (that is, the transmittance is 3% or less), and the transmittance of the light in the second wavelength band polarized in the second direction (blue light BL2p) is, for example, 97% or more (that is, The reflectance is 3% or less). The second polarization separation film K2 has an average transmittance of light in the third wavelength range (fluorescent light YL), for example, 97% or more (that is, reflectance is 3% or less). Other wavelength regions are not particularly limited. In FIG. 4B, the lines indicating the blue light BL2s, the blue light BL2p, and the fluorescent light YL are shifted so as not to overlap in order to make the drawing easy to see in the wavelength region of 500 nm or more.

  As described above, in the present embodiment, the required polarization separation function is dispersed in the first polarization separation film K1 and the second polarization separation film K2. Therefore, in this embodiment, the design conditions for the optical characteristics of the first polarization separation film K1 and the second polarization separation film K2 are relaxed.

  The excitation light BL1s reflected by the first polarization separation film K1 enters the pickup optical system 27. The pickup optical system 27 condenses the excitation light BL1s toward the phosphor layer 32, and includes, for example, a pickup lens 27a and a pickup lens 27b. The excitation light BL1s collected by the pickup optical system 27 enters the fluorescent light emitting element 28.

  The fluorescent light emitting element 28 includes a phosphor layer 32 and a reflective substrate (second reflective element) 33 that supports the phosphor layer 32. In the fluorescent light emitting element 28, the phosphor layer 32 is fixedly supported on the reflective substrate 33 with the surface of the phosphor layer 32 opposite to the side on which the excitation light BL <b> 1 s is incident in contact with the reflective substrate 33. In the reflection substrate 33, the support surface side of the phosphor layer 32 is configured by a specular reflection surface. The specular reflection surface reflects the fluorescent light YL generated by the phosphor layer 32.

  The phosphor layer 32 includes a phosphor that is excited by absorbing the excitation light BL1s that is light in the first wavelength range, and the phosphor that is excited by the excitation light BL1s is different from the first wavelength range. As light in the third wavelength range, for example, fluorescent light (yellow light) YL having a peak wavelength in a wavelength range of 500 to 680 nm is generated.

  As the phosphor layer 32, it is preferable to use a layer excellent in heat resistance and surface processability. For example, as the phosphor layer 32, a phosphor layer in which phosphor particles are dispersed in an inorganic binder such as alumina, or a phosphor layer in which phosphor particles are sintered without using a binder is preferably used. it can.

  In the present embodiment, the phosphor layer 32 is fixed to the reflective substrate 33 by an inorganic adhesive S having light reflection characteristics provided on the side surface. Thereby, the fluorescent light emitting element 28 can reflect the light leaking from the side surface of the phosphor layer 32 into the phosphor layer 32 by the inorganic adhesive S having the light reflection characteristic. Therefore, the light extraction efficiency of the fluorescent light generated by the phosphor layer 32 can be increased.

  A part of the fluorescent light YL generated in the phosphor layer 32 is reflected by the reflective substrate 33 and is emitted to the outside of the phosphor layer 32. Further, of the fluorescent light YL generated by the fluorescent material layer 32, another part of the fluorescent light is directly emitted outside the fluorescent material layer 32 without passing through the reflective substrate 33. In this way, the fluorescent light YL is emitted from the phosphor layer 32 toward the pickup optical system 27.

  A heat sink 34 is disposed on the surface of the reflective substrate 33 opposite to the surface that supports the phosphor layer 32. The heat sink 34 dissipates heat from the phosphor layer. Thereby, the fluorescent light emitting element 28 can prevent the phosphor layer 32 from being thermally deteriorated.

  The fluorescent light YL transmitted through the pickup optical system 27 enters the polarization beam splitter 25. The fluorescent light (yellow light) YL emitted from the phosphor layer 32 enters the polarization beam splitter 25 with the polarization directions not aligned. The fluorescent light YL passes through the first polarization separation film K1 and the second polarization separation film K2, and further enters the integrator optical system 29.

  On the other hand, the blue light BL2p transmitted through the first polarization separation film K1 enters the polarization conversion device 45. The polarization conversion device 45 includes a phase difference plate 26, pickup lenses 41 and 42, and a reflection element 43. The phase difference plate 26 is composed of a quarter wavelength plate (λ / 4 plate). The P-polarized blue light BL2p incident on the phase difference plate 26 is converted into circularly-polarized blue light BL2c and then incident on the pickup lenses 41 and 42. The pickup lenses 41 and 42 collect the blue light BL <b> 2 c toward the reflection element 43.

Next, the configuration of the reflective element 43 will be described with reference to the drawings. FIGS. 5A, 5 </ b> B, and 5 </ b> C are diagrams illustrating a schematic configuration of the reflective element 43 according to the present embodiment.
In the present embodiment, it is preferable that the reflective element 43 adopt any one of the configurations shown in FIGS. 5 (a), (b), and (c).

The reflective element 43 shown in FIG. 5A includes a base member 61, an uneven portion 61a formed on the surface of the base member 61, and a reflective film 62 provided on the uneven portion 61a. The reflective film 62 is made of a reflective metal film such as an Al film, for example. Therefore, various materials can be used for the base member 61 regardless of the presence or absence of light reflectivity.
The reflective element 43 has a function of diffusing and reflecting the circularly polarized blue light BL2c toward the polarization beam splitter 25 side by the reflective film 62 and the uneven portion 61a. In addition, when reflecting the blue light BL2c, the reflecting element 43 brings the way of spreading the blue light BL2c closer to the way of spreading the fluorescent light YL emitted from the phosphor layer.

  The reflective element 43 emits the blue light BL2c as circularly polarized light whose rotation direction is reversed. Thereby, the polarization direction of the light in the second wavelength band when entering the second optical element can be reliably set to the first direction.

The reflective element 43 shown in FIG. 5B includes a base member 63 and a concavo-convex portion 63 a formed on the surface of the base member 63. The base member 63 is made of, for example, a reflective metal material such as an Al film. Therefore, it is not necessary for the reflective element 43 to provide a reflective film on the surface of the uneven portion 63a.
The reflective element 43 has a function of diffusing and reflecting the circularly polarized blue light BL2c toward the polarization beam splitter 25 side by the concave and convex portion 63a. In addition, the reflective element 43 brings the way of spreading the blue light BL2c closer to the way of spreading the fluorescent light YL emitted from the phosphor layer, as in the case of FIG. The reflective element 43 reflects the blue light BL2c as circularly polarized light whose rotation direction is reversed.

The reflective element 43 shown in FIG. 5C includes a base member 64, a concavo-convex portion 64 a formed on the surface of the base member 64, and a reflective film 65 formed on the back surface of the base member 64. The base member 64 is made of, for example, a light transmissive material.
The reflective element 43 diffuses and reflects the blue light BL2c transmitted through the base member 64 toward the polarization beam splitter 25 side by the reflective film 65. In addition, the reflective element 43 makes the way of the blue light BL2c spread close to the way of the fluorescent light YL emitted from the phosphor layer, as in the case of FIGS. The reflective element 43 reflects the blue light BL2c as circularly polarized light whose rotation direction is reversed.

  The circularly polarized blue light BL2c reflected by the reflective element 43 is converted to S-polarized blue light BL2s by passing through the phase difference plate 26. The blue light BL2s enters the second polarization separation film K2 via the second prism 53 of the polarization beam splitter 25, and is reflected toward the integrator optical system 29 by the second polarization separation film K2.

  In this manner, the illumination light (white light) WL is obtained by mixing the blue light BL2s and the yellow fluorescent light YL by the polarization beam splitter 25. This illumination light WL is incident on the integrator optical system 29.

  The integrator optical system 29 equalizes the luminance distribution (illuminance distribution), and includes a pair of lens arrays 29a and 29b. The pair of lens arrays 29a and 29b is composed of a plurality of lenses arranged in an array. Then, the illumination light WL whose luminance distribution is made uniform by passing through the integrator optical system 29 is incident on the polarization conversion element 30.

  The polarization conversion element 30 aligns the polarization direction of the illumination light WL, and is composed of, for example, a combination of a polarization separation film and a retardation plate. In particular, the polarization conversion element 30 converts one polarization component into the other polarization component in order to make the polarization direction of the fluorescent light YL whose polarization direction is not uniform coincide with the polarization direction (S-polarized light) of the blue light BL2s. Then, the illumination light WL whose polarization direction is aligned by passing through the polarization conversion element 30 enters the superimposing optical system 31.

  The superimposing optical system 31 includes a superimposing lens 31a, and the illumination light WL is superimposed on the light modulation device by passing through the superimposing optical system 31. Thereby, the illuminance distribution on the light modulation device is made uniform, and the axial symmetry of the illuminance around the light axis is enhanced.

  In the illuminating device 2 having the above-described configuration, the polarization beam splitter 25 reflects the excitation light BL1 in the first wavelength region and transmits the blue light BL2 in the second wavelength region, thereby allowing the first wavelength to be transmitted. Illumination light (white light) WL in which fluorescent light YL (yellow) generated by causing the excitation light BL1 in the region to enter the phosphor layer 32 and blue light BL2 in the second wavelength region reflected by the reflective element 43 are mixed. Can be generated.

  In the present embodiment, the polarization beam splitter 25 includes a first polarization separation film K1 provided on the first surface side of the base material 51 and a second polarization provided on the second surface side of the base material 51. And a separation membrane K2. As a result, the required polarization separation function can be dispersed in the first polarization separation film K1 and the second polarization separation film K2. Accordingly, the first polarization separation film K1 and the second polarization separation film K2 are designed so that the design conditions of the respective optical characteristics are relaxed, and thus the respective designs are facilitated. As a result, a polarization separation element having desired optical characteristics can be easily and reliably manufactured. Therefore, the yield of the polarization beam splitter 25 is improved, and the cost can be reduced.

  Therefore, by applying such an illuminating device 2 to the illuminating device of the projector 1, the projector 1 itself is also highly reliable with desired optical characteristics obtained at low cost. Further, the projector 1 can perform display with excellent image quality.

In addition, this invention is not necessarily limited to the thing of the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, the polarization beam splitter 25 is not limited to a prism shape, and a flat plate dichroic mirror may be used. In this case, the first polarization separation film K1 is provided on the first surface of the light-transmitting substrate (base material), and the second polarization separation film K2 is disposed on the second surface opposite to the first surface of the substrate. Is provided.

Moreover, in the said embodiment, although the case where the semiconductor laser 21a and the semiconductor laser 21b were used was mentioned as an example as a light source with which the illuminating device 2 is provided, this invention is not limited to this, For example, a light emitting diode (LED). A solid light-emitting element such as may be used. For example, when an LED is used instead of the semiconductor laser 21a, it is preferable to convert light emitted from the LED into S-polarized light using a polarization conversion element. According to this configuration, the phosphor layer 32 can be efficiently irradiated with light emitted from the LED.
Moreover, when using LED instead of the semiconductor laser 21b, it is preferable to convert the light inject | emitted from LED into P polarized light using a polarization conversion element. According to this structure, the illuminating device 2 can inject | emit the light from LED toward the color separation optical system 3 efficiently.

  Moreover, in the said embodiment, although the reflective board | substrate 33 was used as a reflective element, this invention is not limited to this. For example, a reflective film provided between a substrate such as copper having a relatively high thermal conductivity and the phosphor layer 32 may be used as the reflective element. As the reflective film, a high reflectivity material such as aluminum can be used.

  Moreover, in the said embodiment, although the case shown to Fig.5 (a), (b), (c) was mentioned as an example as an aspect of the reflective element 43, this invention is not limited to this. For example, you may use the perfect diffuse reflection surface comprised by apply | coating coating materials, such as barium sulfate and magnesium oxide, to the surface.

  In the above-described embodiment, the projector 1 including the three light modulation devices 4R, 4G, and 4B is exemplified. However, the projector 1 may be applied to a projector that displays a color image (image) with one light modulation device. Furthermore, the light modulation device is not limited to a liquid crystal panel, and for example, a digital mirror device (DMD: registered trademark of Texas Instruments Inc., USA) can be used.

DESCRIPTION OF SYMBOLS 1 ... Projector, 2 ... Illuminating device, 3 ... Color separation optical system, 4R, 4G, 4B ... Light modulation device, 6 ... Projection optical system, 21A ... 1st array light source (1st light source), 21B ... 2nd array Light source (second light source), 25... Polarization beam splitter (polarization separation element), 26... Retardation plate, 27 .. pickup optical system, 32 .. phosphor layer, 33 .. reflective substrate (second reflection element), 43 ... reflective element (first reflective element), 45 ... polarization conversion device, 51 ... base material, 52 ... first prism, 53 ... second prism, SCR ... screen, YL ... fluorescent light (third wavelength range) ), BL1 ... excitation light (light in the first wavelength range), BL2 ... blue light (light in the second wavelength range), K1 ... first polarization separation film, K2 ... second polarization separation film, BL1s ... excitation light (light in the first wavelength band polarized in the first direction), BL2p ... blue Light (second wavelength range of the light polarized in the second direction), BL2s ... blue light (second wavelength range of the light polarized in a first direction)

Claims (9)

A base material having a first surface and a second surface opposite the first surface;
The first surface provided on the first surface side of the base material mainly reflects light in a first wavelength band polarized in a first direction and polarized in a second direction orthogonal to the first direction. A first optical element that mainly transmits light in a second wavelength range different from light in the first wavelength range;
Provided on the second surface side of the substrate, mainly reflects the light in the second wavelength band polarized in the first direction, and reflects the light in the second wavelength band polarized in the second direction. And a second optical element that mainly transmits light. The polarization separation element according to claim 1, wherein the first optical element and the second optical element mainly transmit light in a third wavelength range. A first prism provided so as to sandwich the first optical element with the base material;
The polarization separation element according to claim 1, further comprising: a second prism provided so as to sandwich the second optical element between the base material. The polarization separation element according to any one of claims 1 to 3,
A first light source provided on the first optical element side of the polarization separation element and emitting light in the first wavelength range;
A second light source that is provided on the first optical element side of the polarization separation element and emits light in the second wavelength range;
A phosphor layer provided on an optical path of light in the first wavelength range reflected by the first optical element, and emitting light in a third wavelength range;
The second optical element is provided on the optical path of the light in the second wavelength range that has passed through the polarization separation element, and changes the polarization direction of the incident light from the second direction to the first direction. A polarization conversion device that emits light so as to enter the illumination device. The illuminating device according to claim 4, wherein the polarization conversion device includes a first reflection element that reflects light in the second wavelength range, and a retardation plate. The lighting device according to claim 5, wherein the first reflecting element diffusely reflects the light in the second wavelength range. The light in the second wavelength region enters the reflective element as circularly polarized light,
The lighting device according to claim 5, wherein the first reflecting element emits light in the second wavelength band as circularly polarized light whose rotation direction is reversed. The illumination according to any one of claims 4 to 7, further comprising a second reflecting element that reflects the light in the third wavelength range emitted from the phosphor layer so as to be incident on the polarization separation element. apparatus. An illumination device that emits illumination light;
A light modulation device that forms image light by modulating the illumination light according to image information;
A projection optical system for projecting the image light,
The projector which uses the illuminating device as described in any one of Claims 4-8 as the said illuminating device.

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