WO2019088124A1

WO2019088124A1 - Optical irradiation device and integrator for polarized light source

Info

Publication number: WO2019088124A1
Application number: PCT/JP2018/040390
Authority: WO
Inventors: 寿行高岩; 黒田　敏裕; 山口　正利; 駿檜山
Original assignee: 日立化成株式会社
Priority date: 2017-10-30
Filing date: 2018-10-30
Publication date: 2019-05-09

Abstract

The present invention provides an optical irradiation device which contributes to power saving and the reduced size, and is capable of improving light use efficiency by emitting polarized light. The optical irradiation device comprises a polarized light source 1 for emitting polarized light and an optical integrator 2 that has an incidence surface 21 whereon incidence light PL1 from the polarized light source 1 is incident and has an emission surface 22 opposite the incidence surface 21 for emitting the incidence light PL1 as emission light PL2. The emission light PL2 from the optical integrator 2 is polarized.

Description

Light irradiation device and integrator for polarized light source

The present invention relates to a light irradiation apparatus for irradiating light having polarization characteristics and an integrator for a polarized light source.

2. Description of the Related Art In an image projection apparatus for a display device such as a projector, an optical system which divides light sources of three colors of red, green and blue in time and makes them color is common. This colorization technique is usually a technique called field sequential color (hereinafter referred to as FSC).
In order to use the FSC, light beams of three colors having high color mixing and homogeneity can be obtained by using LCOS (Liquid Crystal On Silicon), LC (Liquid Crystal), DMD (Digital Mirror Device), and MEMS (MEMS) mounted in the image projection apparatus. It is necessary to irradiate an optical element such as Micro Electro Mechanical Systems).

Patent Document

1, 2 and the like disclose an image projection apparatus using a transparent rod. Regarding color mixing and homogeneity of light beams from multiple light sources, Patent Document 1 describes a method of guiding light beams from multiple light sources to a rod with a lens. Patent Document 2 describes a method in which light beams from a plurality of light sources are combined by a dichroic mirror and then guided to a rod.

In recent years, development of wearable display devices represented by a head mounted display has been advanced. In order to be worn on the body, a video projection apparatus for wearable display devices is required to be bright and small while saving power.
In order to miniaturize the image projection apparatus, it is conceivable to use a multi-chip light source in which a plurality of light sources are mounted in one casing. When using a multi-chip light source, the rods proposed in

Patent Documents

1 and 2 need to sufficiently exhibit the function as a light integrator in order to satisfy color mixing and homogeneity. Since an integrator is needed, it is not suitable for miniaturization.

In addition, in optical elements exhibiting polarization dependence such as LCOS and LC, the utilization efficiency of light changes depending on the polarization component of incident light. For example, when the polarization component of the incident light matches the polarization dependence of the optical element, the light utilization efficiency is good. On the other hand, when the incident light is contrary to the polarization dependency of the optical element such as having no polarization component, the utilization efficiency of the light is low.

Japanese Patent Application Laid-Open No. 2004-334083 JP 2000-131665 A

An object of the present invention is to solve the above-mentioned problems, to contribute to power saving and miniaturization, and to provide a light irradiation device and an integrator for a polarized light source which improve the utilization efficiency of light by emitting polarized light. It is.

The present invention relates to the following.
(1) A polarized light source that emits polarized light, and an optical integrator that has an incident surface on which incident light from the polarized light source is incident, faces the incident surface, and has an exit surface that emits the incident light as exit light A light irradiation apparatus, comprising: the light emitted from the light integrator has polarization.
(2) The luminance of the polarization component of the emitted light orthogonal to the polarization direction of the incident light is L _1, and the luminance of the polarization component of the emitted light parallel to the polarization direction of the incident light is L ₂ When it has, the light irradiation apparatus of (1) whose polarization degree P calculated by following formula (1) is 5% or more.
P = {(L ₂ −L ₁ ) / (L ₂ + L ₁ )} × 100 (1)
(3) The light integrator includes a light guide member and scattering particles held by the light guide member,
The refractive index N ₁ of the light guide member is different from the refractive index N ₂ of the scattering particles, the light irradiation device (1) or (2).
(4) The light irradiation device according to any one of (1) to (3), wherein the outer shape of the light integrator is substantially in the shape of a square pole.
(5) The light irradiation device according to any one of (1) to (3), wherein the outer shape of the light integrator is a substantially square frustum shape.
(6) The light irradiation device according to any one of (1) to (5), wherein an outer peripheral surface of the light integrator makes an angle of 0 degrees to 30 degrees with respect to the polarization direction of the incident light.
(7) The outer circumferential surface of the light integrator has a parallel surface substantially parallel to the polarization direction of the incident light and a right angle surface substantially perpendicular to the polarization direction of the incident light. One of the light irradiation devices.
(8) A polarized light source has an incident surface on which incident light having polarization emitted is incident, has an emission surface facing the incident surface, and emits the incident light as emission light, and the emission light has polarization , Integrator for polarized light source.

According to the present invention, it is possible to provide a light irradiation device and an integrator for a polarized light source that contribute to power saving and miniaturization, and improve the utilization efficiency of light by emitting light having polarization.

It is a perspective view (the 1) for explaining one mode of the light irradiation device of the present invention. It is a perspective view (the 2) for explaining one mode of the light irradiation device of the present invention. It is a perspective view (the 1) for explaining one mode of the light integrator with which the light irradiation device of the present invention is provided. It is a perspective view (the 2) for explaining one mode of the light integrator with which the light irradiation device of the present invention is provided. It is a schematic diagram for demonstrating the one aspect which measures the brightness | luminance of the light irradiation apparatus of this invention. It is a top view for explaining the field which measures the luminosity of light irradiation device of the present invention. It is a top view for demonstrating one aspect which calculates the degree of polarization P of the light irradiation apparatus of this invention. It is a top view for demonstrating the rotation angle of the light integrator of this invention.

[Light irradiation device]
The light irradiation apparatus according to the embodiment of the present invention has, as shown in FIG. 1, a polarized light source 1 emitting polarized light, and an incident surface 21 on which incident light PL ₁ from the polarized light source ₁ is incident. And an optical integrator 2 having an emission surface 22 for emitting the incident light PL ₁ as the emitted light PL ₂ . The light PL ₂ emitted from the light integrator 2 is characterized by having polarization.

Light irradiation apparatus according to the embodiment of the present invention, the luminance of the polarized component of the emitted light PL ₂ perpendicular to the polarization direction of the incident light PL ₁ and L _1, parallel to the polarization direction of the incident light PL ₁ If the luminance of the polarized component of the emitted light PL ₂ which was L _2, it is preferred polarization P is calculated by the following formula (1) it is 5% or more.
P = {(L ₂ −L ₁ ) / (L ₂ + L ₁ )} × 100 (1)

The light irradiation apparatus having a degree of polarization P of 5% or more can improve the utilization efficiency of light when it is irradiated to an optical element exhibiting light dependence. From this point of view, the degree of polarization P is more preferably 15% or more, further preferably 25% or more, still more preferably 35% or more, and particularly preferably 50% or more. The upper limit value of the polarization degree P is not particularly limited, but may be 95% or less, 90% or less, or 85% or less.

The polarized light source 1 is a light source that emits polarized light which is light polarized in a specific direction. As the polarized light source 1, for example, a laser emitting linearly polarized light can be used. In addition, as the polarized light source 1, a light source that emits partially polarized light in which light in many vibration directions is mixed can be used.
The polarized light source 1 only needs to emit polarized light as light incident on the light integrator 2, and as shown in FIG. 2, when using a non-polarized light source 11 such as an LED, polarized light such as a polarizing plate, polarizing filter and polarizing prism The child 12 may be used in combination.
The polarized light source 1 may have one light emitting point or two or more light emitting points having the same polarization component.

The light integrator 2 includes, as shown in FIG. 3, an incident surface 21 for receiving light, an emitting surface 22 for emitting light, and side surfaces 23 to 26 connecting the incident surface 21 and the emitting surface 22. The light incident on the light integrator 2 propagates from the incident surface 21 side toward the emission surface 22, and part of the propagating light is reflected by the side surfaces 23 to 26 and is guided to the emission surface 22.
When light from the polarized light source 1 having two or more light emitting points is incident on the incident surface 21 of the light integrator 2, the light is scattered and propagated in the direction of the emission surface 22, so the light spreads inside. Light having high color mixing and uniformity is emitted from the emission surface 22.

The light integrator 2 preferably includes the light guide member 30 and the scattering particles 31 held by the light guide member 30. The refractive index N ₁ of the light guide member 30 is preferably different from the refractive index N ₂ of the scattering particles 31.
According to Snell's law, the light incident on the light integrator 2 is emitted at an angle different from the incident angle when passing through a medium having a different refractive index. The scattering particles 31 have a function of scattering by changing the angle of a light beam traveling according to Snell's law. Relationship of the refractive index N ₂ of the refractive index N ₁ and scattering particles 31 of the light guide member 30, according to Snell's law, and the difference is a large difference relationship because greater diffusion function is obtained by increased .

The shape of the scattering particle 31 is not particularly limited, but it is preferable to use, for example, a spherical shape, a cylindrical shape, an elliptical columnar shape, and a polygonal columnar shape. Among them, spherical shape is more preferable in terms of availability and cost.
When the scattering particles 31 are spherical, the smaller the particle size (diameter of the particles), the larger the angle at which the light beam is bent, and high scattering performance can be obtained. The particle diameter of the scattering particles 31 is preferably larger than the wavelength of the incident light beam and not more than 10 times the wavelength. When the diameter of the scattering particles 31 is smaller than the wavelength of the incident light, large scattering is obtained. However, since it is less likely that the light beam strikes the scattering particles 31, the filling factor of the scattering particles 31 will be increased to ensure homogeneity, and there is a concern that the light utilization efficiency will decrease. When the diameter is larger than the wavelength of the incident light beam, the concern about the reduction in the utilization efficiency tends to disappear, which is preferable. Conversely, when the particle diameter of the scattering particle 31 becomes 10 times or more of the wavelength of the incident light beam, the angle which can change the angle of the advancing light beam becomes smaller, and the light integrator 2 is lengthened to obtain desired color mixture and homogeneity. Therefore, by making the wavelength 10 times or less, it tends to be easy to contribute to the targeted miniaturization.
Even if the scattering particles 31 are other than spherical, in the case where there is no unevenness on the surface, it can be said that substantially the same as above.
Of course, the fine structure of the wavelength order may be provided on the surface of the scattering particle 31. In this case, even if the shape is made arbitrary and the particle diameter of the scattering particles 31 is increased, it can be expected that a large scattering effect can be obtained.
The shape, size, and volume ratio of the scattering particles 31 may be appropriately adjusted in consideration of the above viewpoints.

The scattering particles 31 reduce the transmittance and the polarization maintenance rate depending on the number of collisions with light. That is, the abundance of the scattering particles 31 is inversely proportional to the mean free path, which is the average distance at which the light and the scattering particles 31 collide. In addition, the light transmittance and the polarization maintenance rate fall in proportion to the number of times the light and the scattering particle 31 collide, so they are proportional to the mean free path, which is the average distance that the light and the scattering particle 31 collide. That is, the abundance ratio of the scattering particles 31 is inversely proportional to the brightness and the degree of polarization. When the abundance ratio of the scattering particles 31 is high, the utilization efficiency of light is lowered. Therefore, the filling amount of the scattering particles 31 may be appropriately determined in consideration of the color mixing property, the homogeneity and the utilization efficiency of the light.

The outer shape of the light integrator 2 is preferably a substantially quadrangular prism as shown in FIG. Here, the “substantially square pole shape” refers to a shape that can be regarded substantially as a square pole shape. In the present specification, "about XXX" means that it can be regarded as substantially XXX, unless otherwise specified.
The area (height H × width W) of the light incident surface 21 and the light emission surface 22 may be substantially equal to the area formed by the light incident on the light incident surface 21 from the viewpoint of making the utilization efficiency of the light incident good. Preferably, the minimum size is preferably set in consideration of at least the mounting tolerance. When the height H and the width W of the incident surface 21 and the emission surface 22 are substantially equal to the incident light beam, it is preferable to adjust at the time of assembly in consideration of the mounting tolerance.
The area (height H × width W) of the incident surface 21 is preferably approximately equal to the area formed by the light incident on the incident surface 21 from the viewpoint of improving the light beam uptake, and is equal to or greater than Is more preferred.

The luminance of the light beam exiting the exit surface 22 is inversely proportional to the area of the exit surface 22 with respect to the area formed by the light incident on the entrance surface 21. In other words, if the area of the exit surface 22 is doubled with respect to the area formed by the light incident on the entrance surface 21, the luminance of the light beam exiting the exit surface 22 is halved. In addition, when the area of the exit surface 22 is increased, the effect of confinement is reduced, and the color mixing performance is also reduced. For this reason, it is necessary to increase the abundance ratio of the scattering particles 31, and in such a case, the light utilization efficiency and the luminance tend to further deteriorate.
Preferably, the area of the exit surface 22 is adjusted to be substantially equal to the area formed by the light incident on the entrance surface 21 or set to twice or less in consideration of assembly tolerance.

When the relationship between the width W and height H of the entrance surface 21 and the exit surface 22 is width W> height H, the length L is at least three times the width W from the viewpoint of improving color mixing and homogeneity. The width W is preferably 4 or more, more preferably 5 or more. When the length L is set to three or more times the width W, adjustment to reduce the percentage of the scattering particles 31 tends to maintain the light utilization efficiency while satisfying the color mixing property and the homogeneity.

It is preferable that the entrance surface 21 and the exit surface 22 be substantially parallel. Since the incidence surface 21 and the emission surface 22 are substantially parallel, it is possible to enter and exit light while maintaining the average angle of light vertically incident on the incidence surface 21, and it is possible to maintain the utilization efficiency of light. It is in.
It is desirable that the entrance surface 21 and the exit surface 22 have the same shape. Since the entrance surface 21 and the exit surface 22 have the same shape, leakage of light due to internal reflection by the side surfaces 23 to 26 can be reduced, and efficient reflection on the side surfaces 23 to 26 can be performed. It tends to be able to reduce the loss.

The outer peripheral surface of the optical integrator 2 (side 23-26) is preferably an angle with respect to the polarization direction of the incident light PL ₁ is less than 30 degrees 0 degrees. When the outer peripheral surface (side surfaces 23 to 26) of the light integrator 2 is in the above range, the outgoing light PL ₂ maintaining the polarization of the incident light PL ₁ tends to be able to be obtained. The degree is more preferably 0 degree, still more preferably 0 degree to 10 degrees, and particularly preferably 0 degree.
The outer peripheral surface of the optical integrator 2 (side 23-26), especially have a polarization direction parallel plane is substantially parallel incident light PL _1, a polarization direction of the incident light PL ₁ and perpendicular surface is substantially perpendicular preferable. The "substantially parallel" refers to capable of either the polarization direction of the incident light PL ₁ of the outer peripheral surface of the optical integrator 2 (side 23-26) is considered to become substantially parallel. Further, “substantially orthogonal” as used herein means that any of the outer peripheral surfaces (side surfaces 23 to 26) of the light integrator 2 and the polarization direction of the incident light PL ₁ can be regarded as substantially perpendicular. .

The outer shape of the light integrator 2 is preferably substantially frustum-shaped. Here, the substantially frustum shape means a substantially polygonal frustum shape, a substantially frusto-conical shape, or the like. In addition, even if one pair of parallel inclined slopes of the substantially quadrangular frustum shape is in parallel, it is substantially frustum shape. The external shape of the light integrator 2 is, as shown in FIG. 4 among the substantially frustum shapes, the relationship between the width W ₁ of the entrance surface 21 and the width W ₂ of the exit surface 22 is width W ₁ <width W ₂ by relationship height H ₂ of the height H ₁ and the exit surface 22 of the entrance surface 21 is substantially quadrangular pyramid shape the height H _{1 <height} H _2, the outer peripheral surface of the optical integrator 2 (side 23 It is preferable because it is possible to prevent light leakage from (26) and to narrow the angle at which the emitted light is collected and emitted.

The light integrator 2 is not particularly limited as long as the light integrator 2 has a structure including the light guide member 30 and the scattering particles 31 held by the light guide member 30, but can be obtained by the materials and manufacturing method described below.

The material of the light guide member 30 is not particularly limited as long as it is a material having high transparency from the viewpoint of propagating light, and, for example, acrylic photo-curing resin, epoxy-based thermosetting resin, acrylic and polycarbonate Thermoplastic resin, glass and the like can be used. From the viewpoint that mixing with the scattering particles 31 is easy when using the solid scattering particles 31 as the material of the light guiding member 30, and from the viewpoint of improving the working efficiency since steps such as cooling and drying are not required after curing. Among them, a photocurable resin is preferable from the viewpoint of easy processing into a predetermined shape. In addition, it is more preferable to use an acrylic photo-curing resin as a material of the light guide member 30 because the transmittance is high and the utilization efficiency of light can be enhanced.

The material of the scattering particles 31 is not particularly limited as long as it is a material having high transparency, and for example, crosslinked polystyrene particles, plastic particles, glass particles and the like can be used.
The scattering particles 31 can be efficiently present in the light guide member 30 by mixing particles having a refractive index different from that of the light guide member 30.

In order to scatter light, the scattering particles 31 need to have a difference in refractive index from the light guide member 30, and from the viewpoint of suppressing a decrease in light utilization efficiency and easily obtaining the effect of scattering, the light guide member The refractive index difference between 30 and the scattering particles 31 is preferably 0.001 or more, more preferably 0.003 or more, still more preferably 0.005 or more, and 0.050 or more. Is particularly preferred. In addition, the scattering particles 31 make the specific gravity with the light guide member 30 easy to approach, and from the viewpoint of easy mixing with the light guide member 30, the refractive index difference between the light guide member 30 and the scattering particles 31 Is preferably 0.250 or less, more preferably 0.200 or less, still more preferably 0.150 or less, and particularly preferably 0.130 or less. Here, when the refractive indexes of the light guide member 30 and the scattering particles 31 are compared, either refractive index may be large.

The particle diameter of the scattering particles 31 is preferably 0.3 μm or more, more preferably 0.5 μm or more, from the viewpoint of suppressing light scattering and suppressing a decrease in light extraction efficiency. It is more preferably 0.8 μm or more, particularly preferably 1.3 μm or more. Further, the particle diameter of the scattering particles 31 is preferably 5.0 μm or less, more preferably 4.5 μm or less, and 4.0 μm or less from the viewpoint of maintaining appropriate light scattering and polarization. Is more preferable, and 3.0 μm or less is particularly preferable.
The particle diameter of the scattering particles 31 is preferably substantially uniform, but if 90% or more of the particles are included in the above particle diameter range, there is no problem because a desired effect can be obtained.
The average particle size can be measured by a laser light method (dynamic laser light scattering) using Microtrac UPA (particle size analyzer, made by Leeds & Northrup, "MICROTRAC" and "UPA" are registered trademarks). The volume average particle size (d50 value) is meant.

An example of a method of integrating the light guide member 30 and the scattering particles 31 is shown below.
First, a liquid light guide member 30 is prepared. Then, it is obtained by mixing the light guide member 30 and the scattering particles 31 and photocuring it into a predetermined shape.
Other methods such as heat pressing, injection molding and scraping can also be used. Above all, the use of a liquid light guide member 30 is preferable because the scattering particles 31 can be easily mixed, and it is preferably processed into a predetermined shape if the state in which the light guide members 30 are mixed is also liquid. It is more preferable because it is easy.
At the time of product shape preparation, the product height plate may be manufactured and the outer periphery may be cut to make the product size, or a mold having a product size space is manufactured and resin is poured into the mold and hardened to manufacture May be

[Integrator for polarized light source]
The integrator for a polarized light source (light integrator 2) according to the embodiment of the present invention has an incident surface 21 on which incident light PL ₁ having polarized light emitted by the polarized light source 1 is incident, as shown in FIG. facing 21 has an emission surface 22 for emitting incident light PL ₁ as the outgoing light PL _2, the emitted light PL ₂ has a polarization.

Integrator for polarized light source is, when incident light enters PL ₁ having a polarization from the incident plane 21, the outgoing light PL ₂ emitted from the emission surface 22 maintains the polarization, and having a polarization.

Integrator for polarized light source according to an embodiment of the present invention, the luminance of the polarized component of the emitted light PL ₂ perpendicular to the polarization direction of the incident light PL ₁ and L _1, to the polarization direction of the incident light PL ₁ When the luminance of the polarization component of the parallel outgoing light PL ₂ is L ₂ , the degree of polarization P calculated by the following formula (1 ′) is preferably 5% or more.
P = {(L ₂ −L ₁ ) / (L ₂ + L ₁ )} × 100 Formula (1 ′)

When the degree of polarization P is 5% or more, the light irradiated from the integrator for polarized light source has a sufficient polarization component, and the light utilization efficiency is good when irradiated to an optical element showing polarization dependency. Can be From this point of view, the degree of polarization P is more preferably 15% or more, further preferably 25% or more, still more preferably 35% or more, and particularly preferably 50% or more. The upper limit value of the polarization degree P is not particularly limited, but may be 95% or less, 90% or less, or 85% or less.

EXAMPLES Hereinafter, the present invention will be more specifically described by way of examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

Example 1
[Production of light integrator]
The light integrator 2 has a quadrangular prism shape having a length L of 4.00 mm, a height H of 1.05 mm, and a width W of 0.80 mm. In the light integrator 2, scattering particles 31 having a refractive index of 1.59 having high transparency are dispersed in the light guide member 30 having a refractive index of 1.49 having high transparency. The volume of the scattering particles 31 is 0.6% with respect to the volume of the light integrator 2.
As the light guide member 30, a Hitachiloid made Hytaloid 9501 (trade name, "Hitaloid" is a registered trademark) is used. This is a urethane acrylate photocurable resin.
As the scattering particles 31, Techpolymer SSX-302ABE (trade name, "Techpolymer" is a registered trademark) manufactured by Sekisui Plastics Co., Ltd. is used. This is a fine particle made of a cross-linked polystyrene resin, and is a monodisperse particle having a spherical shape, an average particle diameter of 2 μm, and a difference of approximately 95% of the whole particles with the average particle diameter within 0.5 μm.

The method of producing the light integrator 2 will be described below.
First, 0.6% of the total volume of fine particles (scattering particles 31) is placed in a medium that is a light curing resin as the light guide member 30, and stirred for about 10 minutes with a stirring rod. Allow to degas sufficiently by natural standing for 4 hours or more after stirring. A space of 50 mm in length, 7 mm in width, and 1.05 mm in depth is created by surrounding the bottom and the side with a metal plate, a resin is poured therein, and a glass plate is placed from above. At this time, prevent air from entering inside.
Thereafter, a UV (Ultra Violet) lamp is irradiated through the glass plate to sufficiently cure the light guide member 30 which is a light curing resin.
Thereafter, the cured product is taken out and attached to a transparent substrate with an adhesive layer (adhesive thickness: 30 μm, PET (polyethylene terephtalate), film thickness: 100 μm laminate), and a ring jig made of SUS403 is adhered Then, a length L of 4.00 mm, a height H of 1.05 mm, and a width W of 0.80 mm were cut out with a dicer (DAC 552, manufactured by Disco Co., Ltd.). When processing the side with a dicer, the blade is fed parallel to the length direction. The side is processed with particle diameter: # 5000 dicing blade, rotation speed: 30,000 rpm (30,000 min ^-1 ), cutting speed: 0.5 mm / s, light input / output surface is particle diameter Using a # 3000 dicing blade, processing was performed at a rotation speed of 30,000 rpm (30,000 min ^-1 ) and a cutting speed of 0.5 mm / s.

[Brightness Measurement Device and Measurement Area]
The light integrator 2 obtained above receives, as shown in FIG. 5, light having polarization emitted from the polarized light source 1 consisting of the LED light source (non-polarized light source 11), polarizing filter (polarizer 12) and diffusion sheet 13. Output light to the measurement polarizer 40. The luminance of the light transmitted through the measurement polarizer 40 is measured by the luminance meter 50. The luminance meter 50 used "CA-1500 (brand name)" by Konica Minolta.
6 is a view seen from the direction of the arrow shown in FIG. 6 first region R ₁ shown in the non-polarized light source 11 light emitted from the polarizer 12, a region transmitting diffusion sheet 13 and the measuring polarizer 40. The second region R ₂ as shown in FIG. 6, the non-polarized light source 11 light polarizer 12 emitted from the diffusion sheet 13, a region that transmits light integrator 2 and the measuring polarizer 40.

[Calculation of polarization degree P]
When placing the polarization direction of the polarization direction for measurement polarizer 40 of the polarizer 12 such that the orthogonal, as shown in FIG. 7 (a), the first region R ₁ is darker. The luminance in the second region R ₂ at this time was measured by the luminance meter 50, the luminance is L ₁ in the above formula (1).
Also, when placed so as to be parallel to the polarization direction of the polarizer 12 the polarization direction of the measuring polarizer 40, as shown in FIG. 7 (b), the first region R ₁ is bright. The luminance in the second region R ₂ at this time was measured by the luminance meter 50, the luminance is L ₂ in the above formula (1).

As shown in FIG. 8A, a parallel plane in which the outer peripheral surface 20 (side surfaces 23 to 26) of the light integrator 2 is substantially parallel to the polarization direction of the incident light (the arrow direction in the drawing) It is assumed that the rotation angle θ of the light integrator 2 is equal to 0 degrees, in which the light integrator 2 has a right-angled plane substantially perpendicular to the angle. Only the light integrator 2 is rotated, and the state of the rotation angle θ = 40 degrees is shown in FIG. That is, an angle between the outer circumferential surface 20 (side surfaces 23 to 26) of the light integrator 2 in FIG. 8A and the polarization direction of the incident light (the direction of the arrow in the figure) is 0 degree. The angle between the outer circumferential surface 20 (side surfaces 23 to 26) of the light integrator 2 and the polarization direction of the incident light (the direction of the arrow in the drawing) is 40 degrees.
The degree of polarization P when the rotation angle θ of the light integrator 2 was changed every 10 degrees from 0 degrees to 180 degrees was calculated, and the results are shown in Table 1.

From Table 1, it is understood that the light integrator 2 in the example 1 emits the light having the polarization degree P of not less than the predetermined value and having the polarization.

Example 2
In Example 1, except that the scattering particles 31 are 0.2%, 0.4%, 0.8%, and 1.0% of the total volume in the medium which is a light curing resin as the light guide member 30. Were the same, and each light integrator 2 was obtained. The degree of polarization P at which the rotation angle θ of the obtained light integrator 2 is 0 degrees is calculated, and the results are shown in Table 2.

It can be seen from Table 2 that even in the light integrator 2 when the concentration in the entire volume of the scattering particles 31 is changed, the degree of polarization P is a predetermined value or more, and light having polarized light is emitted.

The present invention is a light integrator that contributes to power saving and miniaturization, and improves the utilization efficiency of light by emitting light having polarization, and a light irradiation apparatus and an integrator for a polarized light source that adopt this are: The present invention is applicable to a wide range of fields such as light source units, lighting, head-up displays, head-mounted displays, view finders, image projectors, and various optical devices.

DESCRIPTION OF SYMBOLS 1 ... Polarization light source 11 ... Non-polarization light source 12 ... Polarizer 2 ... Light integrator 21 ... Incident surface 22 ... Emitting surface 23-26 ... Side surface 30 ... Light guide member 31 ... Scattering particle

Claims

A polarized light source that emits polarized light;
A light integrator having an incident surface on which incident light from the polarized light source is incident, and having an exit surface facing the incident surface and emitting the incident light as output light;
A light emitting device, wherein the outgoing light of the light integrator has polarization.
If the luminance of the polarized component of the emitted light that is orthogonal to the polarization direction of the incident light is L 1, the luminance of the polarized component of the emitted light which is parallel to the polarization direction of the incident light was set to L 2, The light irradiation apparatus of Claim 1 whose polarization degree P calculated by following formula (1) is 5% or more.
P = {(L 2 −L 1 ) / (L 2 + L 1 )} × 100 (1)
The light integrator includes a light guide member and scattering particles held by the light guide member,
The light irradiation device according to claim 1, wherein the refractive index N 1 of the light guide member is different from the refractive index N 2 of the scattering particles.
The light irradiation device according to any one of claims 1 to 3, wherein the outer shape of the light integrator is substantially in the shape of a square pole.
The light irradiation device according to any one of claims 1 to 3, wherein an outer shape of the light integrator is a substantially square frustum shape.
The light irradiation device according to any one of claims 1 to 5, wherein an outer peripheral surface of the light integrator makes an angle of 0 degrees to 30 degrees with respect to a polarization direction of the incident light.
The outer peripheral surface of the light integrator has a parallel surface substantially parallel to the polarization direction of the incident light, and a perpendicular surface substantially orthogonal to the polarization direction of the incident light. The light irradiation device described in.
A polarized light source having an incident surface on which incident light having polarized light emitted by a polarized light source is incident, having an exit surface facing the incident surface and emitting the incident light as an emitted light, and the emitted light having a polarization Integrator.