WO2011070921A1 - Lighting device and projection display device using same - Google Patents

Abstract

Disclosed is a lighting device comprising: a light source (10); a light guide plate (11) with an end surface to which light emitted from the light source (10) is fed; a quarter-wave plate (14) provided on the light guide plate (11); an HPDLC layer (12) provided on a surface of the light guide plate (11) which is the surface on the reverse side of the surface on which the quarter-wave plate (14) is provided; and a light guide plate (13) provided on a surface of the HPDLC layer (12) which is the surface on the reverse side of the surface on which the light guide plate (11) is provided. The HPDLC layer (12) has a periodic structure in which a liquid crystal layer having liquid crystal molecules oriented in one direction and a polymer layer are alternately layered, wherein the index of refraction of the polymer layer with respect to light which includes predetermined polarized light is different from that of the liquid crystal layer. Each interface between the polymer layer and the liquid crystal layer is oblique to a surface of the quarter-wave plate (14) and curved. An inner surface of each curved portion is positioned towards the light guide plate (11).

Description

Illumination device and projection display device using the same

The present invention relates to an illumination device for a projection display device represented by a liquid crystal projector.

In a liquid crystal projector, it is usually necessary to irradiate a liquid crystal panel with polarized light. For this reason, for example, when an LED (Light Emitting Diode) is used as a light source for illuminating the liquid crystal panel, it is desirable to convert light from the LED (non-polarized light) to improve light utilization efficiency. Specifically, polarization conversion is performed so that one of the orthogonally polarized light components of the non-polarized light from the LED is the same as the other polarized light components. If the polarization conversion efficiency is low, the light utilization efficiency is lowered.

Patent Document 1 describes an illumination device that emits polarized light. This illumination device includes a light guide plate. The light guide plate includes a reflection unit, a polarization separation unit disposed so as to face the reflection unit, and a polarization conversion unit that is provided between the reflection unit and the polarization separation unit and converts a polarization direction of transmitted light. And have.

The light from the light source is incident on the end face of the light guide plate. The incident light propagates in the light guide plate. The polarization separation means transmits P-polarized light and reflects S-polarized light. The P-polarized light that has passed through the polarization separation means is emitted light from the illumination device.

The S-polarized light reflected by the polarization separating means is transmitted through the polarization converting means and reflected by the reflecting means, and this reflected light is transmitted again through the polarization converting means. The S-polarized light is converted into P-polarized light by passing through the polarization conversion means twice in the process from the polarization separation means to the reflection means and in the process from the reflection means to the polarization separation means. The P-polarized light from the polarization conversion means passes through the polarization separation means.

Patent Document 2 describes another illumination device that emits polarized light. This illumination device has a waveguide that emits polarized light. The director has a volume hologram at a position facing the exit surface. The volume hologram selectively diffracts S-polarized light of incident light in the direction of the exit surface. The S-polarized light selectively diffracted by the volume hologram is emitted from the exit surface in a certain direction.

Patent Document 3 describes still another illumination device that emits polarized light. This illuminating device includes a light guide portion in which a polarization scattering control layer including a transparent electrode is sandwiched between first and second light guides, and a light source is disposed on an opposing end surface of the light guide portion. A first quarter-wave plate is provided on the exit surface side of the first light guide, and a second quarter-wave plate is provided at a position facing the first quarter-wave plate. Is arranged. A reflecting plate is disposed at a position facing the second light guide.

In the polarization scattering control layer, a transparent region and a scattering region are formed by partially applying a voltage between the transparent electrodes. A region on the end face side where the light source is provided is a transparent region, and a central region is a scattering region.

The light (non-polarized light) incident on the end face from the light source passes through the transparent area. The light transmitted through the transparent region is repeatedly reflected between the interface between the first light guide and the first quarter-wave plate and the interface between the second light guide and the air, and then the scattering region. Is incident on.

In the scattering region, the S-polarized light component of the incident light is scattered, and the scattered light passes through the first light guide, the first and second quarter-wave plates. This transmitted light is the outgoing light of the illumination device.

On the other hand, the P-polarized component light is transmitted through the scattering region. Part of the P-polarized component light that has passed through the scattering region passes through the first light guide and enters the first quarter-wave plate. The light incident on the first quarter-wave plate is reflected at the interface between the first quarter-wave plate and the air, and this reflected light passes through the first quarter-wave plate again. The light that has passed through the first quarter becomes S-polarized light and passes through the first light guide. The S-polarized light component that has passed through the first light guide is scattered in the scattering region.

JP 2003-207646 A JP 2005-504413 A JP 2002-49037 A

In projection optical systems used for liquid crystal projectors and the like, there is a restriction of etendue determined by the area of the light source and the divergence angle. In order to use the light from the light source as the projection light, the product of the area of the light source and the divergence angle is the product of the area of the display element and the capture angle (solid angle) determined by the F number of the projection lens. Must be: Due to such etendue restrictions, it is necessary to reduce the angular spread (outgoing angle) of illumination light in the projection optical system.

In the thing of patent document 1, since the emission angle of the outgoing light (the range of the angle of the light beam emitted from the outgoing surface with respect to the straight line perpendicular to the outgoing surface, that is, the angular distribution) is large, the illumination is restricted due to etendue restrictions. The light that is not used as light increases, and as a result, the light use efficiency decreases.

In the thing of patent document 2, since the outgoing angle (angle distribution) of outgoing light can be made small by the angle selectivity of a volume hologram, although it is possible to avoid etendue restrictions, Since the diffraction efficiency is highly dependent on the incident angle, the light utilization efficiency is thereby reduced.

In the thing of patent document 3, since the light of the S polarization component scattered in the scattering region is emitted as it is, the emission angle (angle distribution) of the outgoing light is large. For this reason, the light utilization efficiency is lowered due to etendue restrictions, similar to that described in Patent Document 1.

An object of the present invention is to solve the above-mentioned problems of etendue and incident angle dependency, and to reduce the exit angle (angle distribution), and to provide a lighting device with high light utilization efficiency and a projection display using the same. To provide an apparatus.

In order to achieve the above object, the lighting device of the present invention includes:
At least one light source;
A first light guide plate to which light emitted from the light source is supplied to an end surface;
A quarter-wave plate provided on the first light guide plate;
A holographic layer provided on a surface of the first light guide plate on a side opposite to the quarter-wave plate side;
A second light guide plate that is provided on a surface of the holographic layer opposite to the first light guide plate side and returns light incident from the holographic layer to the holographic layer;
The holographic layer is formed by alternately laminating a first liquid crystal layer in which liquid crystal molecules are aligned in one direction and a first polymer layer having a refractive index with respect to light having a predetermined polarization different from that of the first liquid crystal layer. Having a first periodic structure
The first interface between the first polymer layer and the first liquid crystal layer is inclined with respect to the surface of the quarter-wave plate, the first interface is curved, and the curved portion The concave side is located on the first light guide plate side.

The projection display device of the present invention is
In the illumination device, a plurality of light sources having different colors of emitted light are provided as the light source, and the first periodic structure is provided for each color of the plurality of light sources. Equipment,
A display element irradiated with light emitted from the illumination device;
A projection optical system for projecting an image formed by the display element.

Another projection type display device of the present invention comprises a lighting device of each color of red, green and blue, comprising the above lighting device,
A first display element irradiated with red light emitted from the red illumination device;
A second display element irradiated with green light emitted from the green illumination device;
A third display element irradiated with blue light emitted from the blue illumination device;
A projection optical system for projecting each color image displayed on the first to third display elements.

It is a schematic diagram which shows the structure of the illuminating device which is the 1st Embodiment of this invention. It is a perspective view which shows a part of periodic structure of the HPDLC layer of the illuminating device shown in FIG. It is a schematic diagram for demonstrating the effect | action of the periodic structure of the HPDLC layer of the illuminating device shown in FIG. It is a schematic diagram for demonstrating another effect | action of the periodic structure of the HPDLC layer of the illuminating device shown in FIG. It is a schematic diagram for demonstrating another effect | action of the periodic structure of the HPDLC layer of the illuminating device shown in FIG. It is a schematic diagram which shows the path | route until the light supplied from the light source in the illuminating device shown in FIG. 1 is radiate | emitted. It is a schematic diagram which shows a mode that the light supplied from the light source in the illuminating device shown in FIG. 1 propagates. It is a schematic diagram for demonstrating the Bragg reflection conditions in the concave surface of the periodic structure of the HPDLC layer of the illuminating device shown in FIG. It is a schematic diagram for demonstrating the relationship between the emission angle of the light radiate | emitted from the quarter wavelength plate in the illuminating device shown in FIG. 1, and the reflection angle of the light reflected by the HPDLC layer. It is a schematic diagram for demonstrating the conditions of the angle which the tangent of the concave surface in the periodic structure of the HPDLC layer of the illuminating device shown in FIG. 1, and the boundary surface of a HPDLC layer and each light-guide plate. It is a schematic diagram for demonstrating the layer space | interval in the periodic structure of the HPDLC layer of the illuminating device shown in FIG. It is a schematic diagram for demonstrating the conditions with respect to the incident light of the concave surface of the HPDLC layer of the illuminating device shown in FIG. It is a schematic diagram for demonstrating the conditions with respect to the incident light of the convex surface of the HPDLC layer of the illuminating device shown in FIG. It is a schematic diagram for demonstrating the preparation method of a HPDLC layer. It is a schematic diagram which shows the structure of the HPDLC layer of the illuminating device which is the 2nd Embodiment of this invention. It is a schematic diagram for demonstrating the emission conditions of the periodic structure of the HPDLC layer shown in FIG. It is a schematic diagram which shows the structure of the illuminating device which is the 3rd Embodiment of this invention. It is a schematic diagram for demonstrating the effect | action of the HPDLC layer of the illuminating device shown in FIG. It is a schematic diagram for demonstrating the preparation methods of the HPDLC layer of the illuminating device shown in FIG. It is a schematic diagram which shows the modification of the illuminating device which is the 1st Embodiment of this invention. It is a side view which shows the modification of the illuminating device which is the 3rd Embodiment of this invention. It is a top view which shows the modification of the illuminating device which is the 3rd Embodiment of this invention. It is a schematic diagram which shows the structure of a projection type display apparatus provided with the illuminating device of this invention. It is a schematic diagram which shows the path | route until the light supplied from the light source in the modification of the illuminating device shown in FIG. 1 is radiate | emitted.

DESCRIPTION OF SYMBOLS 10 Light source 11, 13 Light guide plate 12 HPDLC layer 14 1/4 wavelength plate

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic diagram showing a configuration of a lighting device according to the first embodiment of the present invention.

As shown in FIG. 1, the lighting device includes a light source 10, light guide plates 11 and 13, an HPDLC (holographic polymer dispersed liquid crystal) layer 12 that is a holographic layer, and a quarter-wave plate 14. The light source 10 is a semiconductor light source such as a light emitting diode (LED) or a semiconductor laser (LD), or a light source called a solid light source.

The light guide plate 11 is provided on one surface side of the HPDLC layer 12, and the light guide plate 13 is provided on the other surface side of the HPDLC layer 12. That is, the HPDLC layer 12 is sandwiched between the light guide plates 11 and 13.

The light from the light source 10 is supplied to the end face of the light guide plate 11. In the light guide plate 11, light incident from the end face propagates through the light guide plate 11 and enters one surface of the HPDLC layer 12. Further, light that has entered the light guide plate 11 from one surface of the HPDLC layer 12 propagates through the light guide plate 11 and is emitted from the surface of the light guide plate 11 opposite to the side in contact with the HPDLC layer 12. .

A reflective surface is formed on the surface of the light guide plate 13 excluding the surface in contact with the HPDLC layer 12. In FIG. 1, only the reflective surfaces 13a to 13c are shown for the sake of convenience, but in addition to this, reflective surfaces may be provided on the near side and the far side as viewed in the drawing. In the light guide plate 13, the light incident from the other surface of the HPDLC layer 12 is reflected by each reflecting surface and again enters the other surface of the HPDLC layer 12.

A reflective surface may be provided on the entire side surface of the HPDLC layer 12 of the light guide plate 11 (front surface, front surface, left and right surfaces as viewed in the drawing).

In the laminated structure of the light guide plates 11 and 13 and the HPDLC layer 12, a reflection surface may be formed on the entire remaining surface except the surface on which the quarter-wave plate 14 is formed and the surface on which the light source 10 is provided. Instead of this reflective surface, the entire remaining surface may be covered with a reflective sheet. The reflective surface may be formed by evaporating Al, Ag, or the like.

The reflection surfaces 13 a and 13 b are provided at a predetermined angle with respect to the end surface of the light guide plate 13. Specifically, the reflection surfaces 13 a and 13 b are provided to be inclined with respect to the end surface of the light guide plate 13 so as to face the other surface of the HPDLC layer 12.

FIG. 2A is a perspective view showing a part of the periodic structure of the HPDLC layer 12. As shown in FIG. 2A, the HPDLC layer 12 includes a liquid crystal layer 21 in which liquid crystal molecules are aligned in one direction and a polymer layer having a refractive index different from that of the liquid crystal layer 21 with respect to light having a predetermined polarization (P-polarized light or S-polarized light). And a periodic structure in which 20 and 20 are alternately stacked. The period of this periodic structure corresponds to the wavelength of light emitted from the light source 10. In the periodic structure, the interface between the polymer layer 20 and the liquid crystal layer 21 includes a plurality of curved portions, and the concave surface of each curved portion faces the light guide plate 11. Specifically, the concave surface of each curved portion in the periodic structure faces in the direction of the end surface side where the light source 10 is provided.

Of the light incident from the light guide plate 11 on the concave surface of each curved portion of the HPDLC layer 12, light that satisfies the Bragg condition with respect to the first polarized light (for example, P-polarized light) is directed toward the light guide plate 11. Light that is reflected (diffracted) and does not satisfy the Bragg condition passes through the HPDLC layer 12. Of the light incident from the light guide plate 11, the light of the second polarization (for example, S polarization) having a polarization state different from the first polarization is transmitted through the HPDLC layer 12.

The quarter-wave plate 14 is provided on the surface of the light guide plate 11 opposite to the surface in contact with the HPDLC layer 12. Of the light incident on the quarter-wave plate 14 from the light guide plate 11, the light whose incident angle satisfies the total reflection condition is reflected in the direction of the light guide plate 11, and other light passes through the quarter-wave plate 14. pass. The light that has passed through the quarter-wave plate 14 is emitted light (circularly polarized light) of the illumination device of this embodiment.

In addition, when obtaining linearly polarized light as the emitted light, another quarter wavelength plate is provided in the optical path of the light emitted from the quarter wavelength plate 14.

Next, the operation of the lighting device of this embodiment will be specifically described.

2B to 2D are schematic diagrams for explaining the operation of the periodic structure of the HPDLC layer 12. FIG. 2B to 2D, one surface of the HPDLC layer 12, that is, the surface in contact with the light guide plate 11 is located on the upper side in the drawing, and the other surface of the HPDLC layer 12, that is, the surface in contact with the light guide plate 13 is illustrated in the drawings. Located on the lower side.

As shown in FIG. 2B, of the light incident from one surface of the HPDLC layer 12 (light propagating from the upper right to the lower left toward the drawing), the concave surface at the boundary surface between the polymer layer 20 and the liquid crystal layer 21 The first polarized light whose incident angle satisfies the Bragg condition is reflected upward in the drawing. According to this concave surface, a plurality of first polarized lights having different incident angles with respect to one surface of the HPDLC layer 12 are approximately aligned in a certain direction (a direction along a straight line perpendicular to one surface of the HPDLC layer 12). Can be aligned and reflected. This means that the incident angle dependence of the diffraction efficiency in the HPDLC layer 12 is small, and the emission angle (angular distribution) of the first polarized light emitted from one surface of the HPDLC layer 12 is small. In the case of a structure (planar surface) that does not use a concave surface, it is difficult to realize such an incident angle dependency and an emission angle (angle distribution) of diffraction efficiency.

The second polarized light passes through the HPDLC layer 12 as it is regardless of the incident angle. That is, as shown in FIG. 2C, the HPDLC layer 12 acts as a polarization separating unit that separates the first polarized light and the second polarized light with respect to light whose incident angle satisfies the Bragg condition.

As shown in FIG. 2D, among the light incident from the other surface of the HPDLC layer 12, the first polarized light whose incident angle at the convex surface of the boundary surface between the polymer layer 20 and the liquid crystal layer 21 satisfies the Bragg condition is Reflected downward toward the drawing. According to the reflection on the convex surface, when a plurality of first polarized light beams having the same incident angle with respect to the other surface of the HPDLC layer 12 are incident on different positions on the convex surface, the first polarized light beams are in different directions. Reflected. In this manner, the first polarized light incident from the other surface of the HPDLC layer 12 can be diffused by the convex surface within a certain angle range corresponding to the convex surface.

Of the first polarized light incident from the other surface of the HPDLC layer 12, light whose incident angle on the convex surface does not satisfy the Bragg condition passes through the HPDLC layer 12 as it is. The second polarized light passes through the HPDLC layer 12 as it is regardless of the incident angle.

FIG. 3A schematically shows a path through which light supplied from the light source 10 into the light guide plate 11 is emitted from the emission surface of the quarter-wave plate 14. In FIG. 3A, an arrow indicated by a solid straight line indicates P-polarized light, and an arrow indicated by a broken straight line indicates S-polarized light. Open arrows indicate unpolarized light including P-polarized light and S-polarized light.

The light incident from the light source 10 into the light guide plate 11 propagates through the light guide plate 11 and then enters the HPDLC layer 12. Of the light incident on the HPDLC layer 12 from the light source 10 via the light guide plate 11, the light (white arrow shown in FIG. 3A) whose incident angle at the concave surface of the boundary surface of the periodic structure satisfies the Bragg condition is P-polarized light and S Separated into polarized light. The separated P-polarized light is reflected toward the light guide plate 11 by the concave surface. The separated S-polarized light passes through the HPDLC layer 12 and enters the light guide plate 13.

The P-polarized light reflected by the concave surface enters the quarter-wave plate 14 via the light guide plate 11. Of the P-polarized light incident on the quarter-wave plate 14, light that does not satisfy the total reflection condition passes through the quarter-wave plate 14, and light that satisfies the total reflection condition is that of the quarter-wave plate 14. The light is reflected in the direction of the light guide plate 11 on the exit surface (the surface opposite to the surface in contact with the light guide plate 11). In the example shown in FIG. 3A, the incident angle of the P-polarized light reflected by the concave surface with respect to the exit surface of the quarter-wave plate 14 does not satisfy the total reflection condition. Therefore, the P-polarized light reflected by the concave surface is emitted from the emission surface of the quarter-wave plate 14.

S-polarized light that has passed through the HPDLC layer 12 and entered the light guide plate 13 is reflected in the direction of the HPDLC layer 12 by the reflecting surface 13c. The S-polarized light reflected by the reflecting surface 13c passes through the HPDLC layer 12 as it is. The S-polarized light transmitted through the HPDLC layer 12 enters the quarter-wave plate 14 through the light guide plate 11. In the example shown in FIG. 3A, the incident angle of the S-polarized light reflected by the reflecting surface 13c with respect to the exit surface of the quarter-wave plate 14 satisfies the total reflection condition. Therefore, the S-polarized reflected light from the reflecting surface 13 c is reflected in the direction of the light guide plate 11 on the exit surface of the quarter-wave plate 14.

Of the reflected light from the reflecting surface 13c, the light reflected by the exit surface of the quarter-wave plate 14 and incident on the light guide plate 11 passes through the quarter-wave plate 14 twice, so that the polarization direction is the other. Is converted into the polarization direction. In the example shown in FIG. 3A, out of the S-polarized reflected light from the reflecting surface 13c, the light transmitted through the quarter-wave plate 14 twice is transmitted to the HPDLC layer 12 through the light guide plate 11 as P-polarized light. Incident.

Of the P-polarized light incident on the HPDLC layer 12 from the light guide plate 11, light whose incident angle on the concave surface satisfies the Bragg condition is reflected in the direction of the light guide plate 11, and light whose incident angle on the concave surface does not satisfy the Bragg condition The HPDLC layer 12 is transmitted as it is. In the example shown in FIG. 3A, the incident angle at the concave surface of the P-polarized light incident on the HPDLC layer 12 satisfies the Bragg condition. Therefore, the P-polarized light incident on the HPDLC layer 12 is reflected in the direction of the light guide plate 11 by the concave surface.

The P-polarized light reflected by the concave surface enters the quarter-wave plate 14 via the light guide plate 11. In the example shown in FIG. 3A, the incident angle of the P-polarized light reflected by the concave surface with respect to the exit surface of the quarter-wave plate 14 does not satisfy the total reflection condition. Therefore, the P-polarized light reflected by the concave surface is emitted from the emission surface of the quarter-wave plate 14.

The P-polarized light reflected in the direction toward the light source 10 by the reflective surface 13a or the reflective surface 13c (in FIG. 3A, P-polarized light traveling from the lower left to the upper right toward the drawing) enters the HPDLC layer 12. In the example shown in FIG. 3A, the incident angle of the P-polarized light incident on the HPDLC layer 12 to the convex surface satisfies the Bragg condition. For this reason, the P-polarized light incident on the HPDLC layer 12 is reflected in the direction of the light guide plate 13 by the convex surface. The reflected light (P-polarized light) from the convex surface that has entered the light guide plate 13 is reflected by the reflective surface 13 c and enters the HPDLC layer 12 again. In the example shown in FIG. 3A, the incident angle to the convex surface of the reflected light (P-polarized light) from the reflecting surface 13c that has entered the HPDLC layer 12 again does not satisfy the Bragg condition. For this reason, the P-polarized light that has entered the HPDLC layer 12 again passes through the HPDLC layer 12, further passes through the light guide plate 11, and enters the quarter-wave plate 11. In the example shown in FIG. 3A, the incident angle of the P-polarized light that has passed through the light guide plate 11 to the quarter-wave plate 11 does not satisfy the total reflection condition. The P-polarized light that has passed through the light guide plate 11 passes through the quarter-wave plate 11 as it is, and is emitted from the exit surface of the quarter-wave plate 11 as outgoing light of the illumination device.

In the illumination device of this embodiment, the light utilization efficiency can be improved and the emission angle (angle distribution) can be reduced by the action of the HPDLC layer 12 as shown in FIGS. 2B to 2D.

In addition, in the illumination device of the present embodiment, in addition to the operations shown in FIGS. 2B to 2D, a part of the light reflected on the concave side and the convex side of the boundary surface of the periodic structure of the HPDLC layer 12 is propagated and reused. Utilization (utilization by circulating light) can further improve light utilization efficiency.

FIG. 3B schematically shows how the light supplied from the light source 10 into the light guide plate 11 propagates between the quarter-wave plate 14 and the light guide plate 13. In FIG. 3B, an arrow indicated by a solid straight line indicates P-polarized light, and an arrow indicated by a broken straight line indicates S-polarized light. Open arrows indicate unpolarized light including P-polarized light and S-polarized light.

Depending on the relationship between the incident angle on one surface of the HPDLC layer 12 and the incident position on the concave surface, the first polarized light reflected by the concave surface when the Bragg condition is satisfied is 1 at the incident angle satisfying the total reflection condition. / 4 incident on the wavelength plate 14. In this case, the first polarized light is reflected in the direction of the light guide plate 11 by the exit surface of the quarter-wave plate 14. In the illumination device of this embodiment, as shown in FIG. 3B, not only the light propagating from the light source 10 side to the opposite side of the light source 10 but also the light propagating in the opposite direction in the HPDLC layer 12 The light can be reflected on the convex side and propagated between the quarter-wave plate 14 and the light guide plate 13. In this propagation process, the incident angle to the HPDLC layer 12 changes due to reflection on the convex surface, the concave surface, and the reflection surfaces 13a and 13b. Further, polarization separation by the HPDLC layer 12 and the quarter wavelength plate 14 are used. Through the polarization conversion, the first polarized light can be emitted from the emission surface of the quarter-wave plate 14.

Next, conditions for setting the exit angle of the polarized light emitted from the exit surface of the quarter-wave plate 14 in the illumination device of the present embodiment within a range satisfying the etendue restrictions will be described.

FIG. 4 is a schematic diagram for explaining the Bragg reflection condition on the concave surface of the periodic structure of the HPDLC layer 12. The angle formed by the boundary surface between the HPDLC layer 12 and the light guide plate 13 and the tangent line of the convex surface is θ _r . When the refractive index of the HPDLC layer 12 is n, the pitch of the periodic structure is d ₁ , the reflection wavelength is λ, and the incident angle is θ _a , the Bragg reflection condition on the concave surface is given by the following formula 1.

Here, N is a positive integer.

The pitch d _{1 of the} periodic structure is given by Equation 2 below.

For example, in the periodic structure shown in FIG. 4, the incident angle of light incident on one surface (surface on the light guide plate 11 side) of the HPDLC layer 12 with respect to the one surface is α ₁ , When the incident angle is θ ₁ , the Bragg reflection condition on the concave surface of the incident light can be obtained by setting N to 1 and the incident angle θ _a to θ _{1 in} the above equation 1. Further, the incident angle with respect to one surface (surface on the light guide plate 11 side) of the HPDLC layer 12 is α ₂ (<α ₁ ), and the incident angle to the concave surface is θ ₂ (> θ ₁ ). The Bragg reflection condition of light on the concave surface can be obtained by setting N to 2 and the incident angle θ _a to θ _{2 in} the above formula 1.

FIG. 5 is a schematic diagram for explaining the relationship between the emission angle of light emitted from the quarter-wave plate 14 and the reflection angle of light reflected by the HPDLC layer 12. φ ₀ is an angle of light emitted from the quarter-wave plate 14 with respect to a perpendicular drawn with respect to the emission surface. φ ₁ is an angle with respect to a perpendicular line of the reflected light from the HPDLC layer 12 drawn with respect to the boundary surface between the HPDLC layer 12 and the light guide plate 11.

As shown in FIG. 5, when the range of the emission angle of the light emitted from the quarter wavelength plate 14 (emission angle distribution) is ± φ ₀ , the reflected light incident on the light guide plate 11 from the HPDLC layer 12 is reflected. the scope of the corner has to do with ± φ _1. φ ₁ is given by Equation 3 below.

Here, n is the refractive index of the light guide plate 11.

According to Equation 3 above, for example, when φ ₀ = 15 ° and n = 1.5, φ ₁ = 9.9 °.

FIG. 6 is a schematic diagram for explaining the condition of the angle between the concave tangent line in the periodic structure of the HPDLC layer 12 and the boundary surface between the HPDLC layer 12 and the light guide plates 11 and 13. The refractive indexes of the light guide plates 11 and 13 and the HPDLC layer 12 are both n.

In FIG. 6, α ₁ indicates an angle (complementary angle) between the light incident from the light guide plate 11 to the HPDLC layer 12 and the boundary surface between the light guide plate 11 and the HPDLC layer 12. β ₁ represents an angle formed by the boundary surface between the light guide plate 11 and the HPDLC layer 12 on the concave surface of the HPDLC layer 12 and the light reflected at the intersection with the tangent line. θ ₁ indicates an incident angle with respect to the concave surface of the light incident on the HPDLC layer 12 from the light guide plate 11.

Α ₂ indicates an angle (complementary angle) between the light guide plate 11 and the boundary surface between the HPDLC layer 12 and the light incident on the HPDLC layer 12 from the light guide plate 13. β ₂ indicates an angle between the light guide plate 13 and the boundary surface between the HPDLC layer 12 and the light reflected at the intersection with the tangent on the convex surface of the HPDLC layer 12. θ ₂ represents an incident angle with respect to the concave surface of the light incident on the HPDLC layer 12 from the light guide plate 13.

From the law of reflection, the following relational expression holds for light incident on the HPDLC layer 12 from the light guide plate 11 at the incident angle α ₁ .

Similarly, the following relational expression holds for light incident on the HPDLC layer 12 from the light guide plate 13 at an incident angle α ₂ .

Here, the reflection wavelength is λ, and the layer interval in the periodic structure of the HPDLC layer 12 is d ₁ . As shown in FIG. 7, since λ and d ₁ are the same between the incident light at the incident angle θ _{1 and} the incident light at the incident angle θ ₂ , from the condition of Bragg reflection,

The relationship is established.

Therefore,

The relationship is established.

From these formulas,

Is obtained.

Since the light having the angles α ₁ , α ₂ , β ₂ is light propagating in the light guide plate,

Get a relationship.

Further, in order to change the emission angle from the HPDLC layer 12 from −φ ₁ to + φ ₁ ,

It is necessary to satisfy the relationship.

As can be seen from the above, in order to change the emission angle from −φ ₁ to + φ ₁ , the tangential angle θ _r of the HPDLC layer 12 is

Given in. At this time, it is necessary to satisfy the following relational expression.

Further, from the expressions 11, 12, and 16, the layer interval d ₁ of the periodic structure of the HPDLC layer 12 is

Given in.

In the illuminating device of this embodiment, the HPDLC layer 12 and the light guide plate are configured so that the emission angle (angular distribution) is limited to a certain angle range (emission condition) and the propagating light is diffused (angle conversion condition). The angle θ _r of the tangent to the 13 boundary surface and the layer interval d of the HPDLC layer 12 are set.

Hereinafter, for the light having the reference angles α ₁ and β ₁ , the angle θ ₁ and the interval d are determined, and based on the determined angle θ ₁ , the angle θ _r satisfying the emission condition and the angle conversion condition described above is determined. A specific example of obtaining is given.

(First Example of HPDLC Layer)
FIG. 8 is a diagram for explaining conditions for incident light on the concave surface of the HPDLC layer 12. FIG. 9 is a diagram for explaining conditions for incident light on the convex surface of the HPDLC layer 12.

In the case where n = 1.5 (α ₁ = 48.1 °), φ ₀ = ± 15 ° (φ ₁ = ± 9.9 °), and λ = 530 nm, at the end on the concave light guide plate 13 side , Α ₁ = 45 ° is reflected, and the reflected light is emitted from the boundary surface between the HPDLC layer 12 and the light guide plate 11 at an emission angle of φ ₁ = 9.9 °. in this case,
θ _r = 17.6 °
β ₁ -90 = 9.9 °
α ₂ = 8.8 °
β ₂ = 136.1 °. The layer spacing d is 398.2 mm.

The concave end portion on the light guide plate 11 side reflects light of α ₁ = 40.8 °, and the reflected light has an emission angle of φ ₁ = 5.7 °, and the boundary between the HPDLC layer 12 and the light guide plate 11. It is emitted from the surface. in this case,
θ _r = 21.8 °
β ₁ -90 = 5.7 °
α ₂ = 4.6 °
β ₂ = 131.9 °
It becomes.

From the above, by forming the HPDLC layer 12 having a concave surface satisfying 17.6 ° ≦ θ _r ≦ 21.8 ° and d = 398.2 mm, the emission angle φ ₀ is in the range of −15 ° to + 15 °. Can be inside.

(Second Example of HPDLC Layer)
In the case where n = 1.55 (α ₁ <49.8 °), φ ₀ = ± 15 ° (φ ₁ = ± 9.6 °), and λ = 530 nm, at the end on the concave light guide plate 13 side , Α ₁ = 45 ° is reflected, and the reflected light is emitted from the boundary surface between the HPDLC layer 12 and the light guide plate 11 at an emission angle of φ ₁ = 9.6 °. in this case,
θ _r = 17.7 °
β ₁ -90 = 9.6 °
α ₂ = 8.7 °
β ₂ = 135.9 °
It becomes. The layer spacing d is 384.8 mm.

The concave end portion on the light guide plate 11 side reflects light of α ₁ = 39.3 °, and the reflected light has an emission angle of φ ₁ = 3.9 °, and the boundary between the HPDLC layer 12 and the light guide plate 11. It is emitted from the surface. in this case,
θ _r = 23.4 °
β ₁ -90 = 3.9 °
α ₂ = 3.0 °
β ₂ = 130.2 °
It becomes.

From the above, by forming the HPDLC layer 12 having a concave surface satisfying 17.7 ° ≦ θ _r ≦ 23.4 ° and d = 384.8 mm, the emission angle φ ₀ is in the range of −15 ° to + 15 °. Can be inside.

(Third embodiment of HPDLC layer)
In the case where n = 1.55 (α ₁ <49.8 °), φ ₀ = ± 15 ° (φ ₁ = ± 9.6 °), and λ = 530 nm, at the end on the concave light guide plate 13 side , Α ₁ = 49 ° is reflected, and the reflected light is emitted from the boundary surface between the HPDLC layer 12 and the light guide plate 11 at an emission angle of φ ₁ = 9.6 °. in this case,
θ _r = 15.7 °
β ₁ -90 = 9.6 °
α ₂ = 11.2 °
β ₂ = 137.4 °
It becomes. The layer spacing d is 378.2 mm.

The concave end portion on the light guide plate 11 side reflects light of α ₁ = 41.8 °, and the reflected light has an emission angle of φ ₁ = 2.4 °, and the boundary between the HPDLC layer 12 and the light guide plate 11. It is emitted from the surface. in this case,
θ _r = 22.9 °
β ₁ -90 = 2.4 °
α ₂ = 4.0 °
β ₂ = 130.2 °
It becomes.

From the above, by forming the HPDLC layer 12 having a concave surface satisfying 15.7 ° ≦ θ _r ≦ 22.9 ° and d = 378.2 mm, the emission angle φ ₀ is in the range of −15 ° to + 15 °. Can be inside.

(Fourth Example of HPDLC Layer)
In the case where n = 1.55 (α ₁ <49.8 °), φ ₀ = ± 15 ° (φ ₁ = ± 9.6 °), and λ = 530 nm, α ₁ = 49 at the center of the concave surface. .0 ° light is reflected, and the reflected light has an emission angle of φ ₁ = 0 ° (meaning that the light is emitted in a direction perpendicular to the emission surface), and the boundary between the HPDLC layer 12 and the light guide plate 11 It is emitted from the surface. in this case,
θ _r = 20.5 °
β ₁ -90 = 0 °
α ₂ = 7.4 °
β ₂ = 131.6 °
It becomes. The layer spacing d is 365.1 mm.

At the end on the concave light guide plate 13 side, light of α ₁ = 49.8 ° is reflected, and the reflected light has an emission angle of φ ₁ = 0.8 °, and the boundary between the HPDLC layer 12 and the light guide plate 11 It is emitted from the surface. in this case,
θ _r = 19.7 °
β ₁ -90 = 0.8 °
α ₂ = 8.2 °
β ₂ = 132.4 °
It becomes.

At the concave end portion on the light guide plate 11 side, light of α ₁ = 47.7 ° is reflected, and the reflected light has an emission angle of φ ₁ = −1.3 °, and the HPDLC layer 12 and the light guide plate 11 It is emitted from the boundary surface. in this case,
θ _r = 21.8 °
β ₁ -90 = -1.3 °
α ₂ = 6.1 °
β ₂ = 130.3 °
It becomes.

From the above, by forming the HPDLC layer 12 having a concave surface satisfying 19.7 ° ≦ θ _r ≦ 21.8 ° and d = 378.2 mm, the emission angle φ ₀ is in the range of −15 ° to + 15 °. Can be inside.

Next, a method for producing the HPDLC layer 12 shown in FIG. 1 will be described.

FIG. 10 is a schematic diagram for explaining a method for producing the HPDLC layer 12. The HPDLC precursor 100 is sandwiched between the substrates 101 and 102, and the laser beam 104 is irradiated from the substrate 101 side, and the laser beam 105 is irradiated from the substrate 102 side through the microlens 103. The laser beams 104 and 105 are P-polarized light or S-polarized light.

The HPDLC precursor 100 includes a polymer layer precursor, a liquid crystal, and an initiator. The liquid crystal is, for example, a nematic liquid crystal. The initiator may contain a sensitizing dye.

The polymer layer precursor is composed of any material of photocuring monomer (or photocuring monomer and oligomer), photocuring liquid crystalline monomer and photocuring polymer liquid crystal precursor, or a combination thereof. The photocurable liquid crystalline monomer has liquid crystallinity before photocuring but does not have liquid crystallinity after photocuring. The photocurable polymer liquid crystal precursor becomes a polymer liquid crystal after photocuring.

When the initiator is removed, the weight ratio of the polymer layer precursor is 80 to 40%, and the weight ratio of the liquid crystal is 20 to 60%.

The laser beam 104 is a reference beam, the laser beam 104 and the laser beam 105 incident through the microlens 103 are caused to interfere with each other, and the state (interference fringes) is recorded in the HPDLC precursor 100. The wavelength of the laser beams 104 and 105, the incident angle of the laser beams 104 and 105 to the HPDLC precursor 100, the shape of the convex surface of the microlens (curvature, etc.), etc. are appropriately set, and the liquid crystal molecules in the liquid crystal layer are oriented in one direction. By orientation, the HPDLC layer 12 shown in FIG. 1 is obtained.

The HPDLC layer 12 in which liquid crystal molecules are aligned in one direction can be produced by various methods similar to the production of a liquid crystal element. An example of the creation procedure will be briefly described below.

First, an alignment film (for example, polyimide) is applied to the surface of the light guide plates 11 and 13 where the HPDLC layer 12 is in contact, and an alignment process such as a rubbing process is performed.

Next, the HPDLC precursor is sandwiched between the surfaces subjected to the alignment treatment, and the HPDLC precursor (liquid crystal component) is aligned between the light guide plates 11 and 13.

Finally, after aligning the HPDLC precursor (liquid crystal component), the HPDLC layer 12 is formed by interference exposure.

In the illuminating device of the present embodiment, when the reflecting surface is formed on the end surface of the light guide plate 11 facing the end surface on which the light source 10 is formed, the shape of the light guide plate 11 is wedged when the light guide plate 11 is viewed from the side. It is good also as a shape. The wedge shape is such that the thickness of the light guide plate 11 gradually decreases from the end surface where the light source 10 is formed toward the end surface where the reflection surface is formed.

The reflection surfaces 13a and 13b are formed so as to intersect with a surface perpendicular to the reflection surface 13c, but are not limited thereto. The reflective surfaces 13a and 13b may be surfaces perpendicular to the reflective surface 13c.

The reflection surface 13c may have at least one convex portion having a triangular cross-sectional shape. Angle conversion can be performed by this convex part.

(Second Embodiment)
FIG. 11 is a schematic diagram showing the configuration of the HPDLC layer of the lighting apparatus according to the second embodiment of the present invention.

The illumination device of the present embodiment has the same configuration as that of the illumination device of the first embodiment except that the HPDLC layer is different. Hereinafter, the configuration of the HPDLC layer will be mainly described, and description of other parts will be omitted.

As shown in FIG. 11, the HPDLC layer 120 has a structure in which the periodic structures 121 and 122 are multiplexed. The periodic structure 121 is the same as the periodic structure of the HPDLC layer 12 in the illumination device of the first embodiment.

The periodic structure 122 is a structure in which polymer layers and liquid crystal layers are alternately stacked. Similar to the periodic structure 121, also in the periodic structure 122, the boundary surface between the polymer layer and the liquid crystal layer is composed of a plurality of curved portions, and the concave surface of each curved portion is the direction of the light guide plate 11 (the direction of the light source 10 shown in FIG. 1). Suitable for. The periodic structures 121 and 122 are formed so that the polymer layer and the liquid crystal layer intersect each other.

The periodic structure 121 satisfies the emission condition and the angle conversion condition described in the first embodiment.

On the other hand, the periodic structure 122 satisfies only the emission conditions. Specifically, the periodic structure 122 is

The emission condition is satisfied. The layer interval d ₂ of the periodic structure 122 is

Satisfy the condition of

In the illuminating device of this embodiment, the periodic structure 121 limits the emission angle and diffuses the propagating light. Since the periodic structure 121 needs to satisfy both the emission condition and the angle conversion condition, even if the emission angle φ ₀ is set to be in the range of −15 ° to + 15 °, the emitted light is emitted over the entire angle range. It is difficult to get.

On the other hand, the periodic structure 122 does not need to consider the angle conversion condition, and only needs to consider the emission condition. Therefore, when the emission angle φ ₀ is set in the range of −15 ° to + 15 °, the emitted light can be obtained over the entire angle range.

As described above, according to the present embodiment, by providing the periodic structure 122, the emission angle φ ₀ is set to be in the range of −15 ° to + 15 ° as compared with that of the first embodiment. In this case, since the emitted light can be obtained over the entire angular range, the light utilization efficiency can be further improved.

Hereinafter, specific examples of the periodic structure 122 will be given.

When n = 1.55 (α ₁ <49.8 °), φ ₀ = ± 15 ° (φ ₁ = ± 9.6 °), and λ = 530 nm, light of α ₁ = 45 ° is reflected. When the reflected light is emitted from the boundary surface between the HPDLC layer 120 and the light guide plate 11 at an emission angle of φ ₁ = 9.6 °, the periodic structure 121 has a condition of 39.3 ° <α ₁ <45 °. Configure to meet.

On the other hand, the periodic structure 122 emits light satisfying α ₁ ≦ 39.3 ° from the boundary surface between the HPDLC layer 120 and the light guide plate 11 at φ ₀ = ± 15 ° (φ ₁ = ± 9.6 °). Configure.

FIG. 12 is a schematic diagram for explaining the emission conditions of the periodic structure 122. At the central part of the concave surface, light of α ₁ = 29.7 ° is reflected, and the reflected light is output at an angle of φ ₁ = 0 ° (indicating that the light is emitted in a direction perpendicular to the emission surface). The light is emitted from the boundary surface between the layer 120 and the light guide plate 11. in this case,
θ _r = 30.2 °
β ₁ -90 = 0 °
It becomes. The layer spacing d is 197.7 mm.

At the end of the concave light guide plate 13 side, light of α ₁ = 39.3 ° is reflected, and the reflected light has an emission angle of φ ₁ = 9.6 °, and the boundary between the HPDLC layer 120 and the light guide plate 11. It is emitted from the surface. in this case,
θ _r = 20.6 °
β ₁ -90 = 9.6 °
It becomes.

At the concave end portion on the light guide plate 11 side, light of α ₁ = 20.1 ° is reflected, and the reflected light has an emission angle of φ ₁ = −9.6 °, and the HPDLC layer 120 and the light guide plate 11 It is emitted from the boundary surface. in this case,
θ _r = 39.8 °
β ₁ -90 = -9.6 °
It becomes.

From the above, by forming the periodic structure 122 so as to satisfy 20.6 ° ≦ θ _r ≦ 39.8 ° and d = 197.7 mm, the emission angle φ ₀ falls within the range of −15 ° to + 15 °. Is possible.

In the illuminating device of the present embodiment, the periodic structure 122 may be formed such that the concave surface thereof has a direction opposite to the direction of the concave surface of the periodic structure 121.

Further, a plurality of periodic structures 121 and 122 may be provided.

Further, the periodic structure 122 may be configured to satisfy only the angle conversion condition, not the emission condition. In this case, the periodic structure 122 is

Satisfy the angle conversion condition. The layer interval d ₃ of the periodic structure 122 is

Satisfy the condition of

According to the above configuration, since the diffusion in the periodic structure 122 can be performed more efficiently, the light utilization efficiency can be further improved as compared with that of the first embodiment.

(Third embodiment)
FIG. 13 is a schematic diagram showing a configuration of a lighting apparatus according to the third embodiment of the present invention.

As shown in FIG. 13, the lighting device includes light sources 10 a and 10 b, light guide plates 11 and 13, an HPDLC layer 220, and a quarter wavelength plate 14. The light guide plates 11 and 13 and the quarter wave plate 14 are the same as those in the first embodiment.

The light sources 10a and 10b are, for example, semiconductor light sources such as light emitting diodes (LEDs) and semiconductor lasers (LD), or light sources called solid light sources. The wavelengths of light emitted from the light sources 10a and 10b are substantially the same. The light source 10 a is provided on one end surface of the light guide plate 11. The light source 10b is provided on the other end surface of the light guide plate 11 (an end surface facing the end surface on which the light source 10a is provided).

The HPDLC layer 220 is sandwiched between the light guide plates 11 and 13. In the light guide plate 11, light incident from the end face propagates through the light guide plate and enters one surface of the HPDLC layer 220. In addition, light incident on the light guide plate 11 from one surface of the HPDLC layer 220 passes through the light guide plate 11 and enters the quarter wavelength plate 14.

In the light guide plate 13, light incident from the other surface of the HPDLC layer 220 is reflected by the reflecting surfaces 13 a to 13 c and is incident on the other surface of the HPDLC layer 220 again.

The HPDLC layer 220 includes a periodic structure 221 in which first polymer layers and first liquid crystal layers are alternately stacked, and a periodic structure 222 in which second polymer layers and second liquid crystal layers are alternately stacked. Have The periodic structures 221 and 222 have the same period and correspond to the wavelength of light emitted from the light sources 10a and 10b.

In the periodic structure 221, the boundary surface between the first polymer layer and the first liquid crystal layer includes a plurality of curved portions, and the concave surface of each curved portion faces the light guide plate 11. Similarly, also in the periodic structure 222, the boundary surface between the second polymer layer and the second liquid crystal layer includes a plurality of curved portions, and the concave surface of each curved portion faces the light guide plate 11 side. Specifically, the concave surface of each curved portion in the periodic structure 221 faces the end surface side where the light source 10a is provided, and the concave surface of each curved portion in the periodic structure 222 is on the end surface side where the light source 10b is provided. Facing the direction.

The periodic structures 221 and 222 are formed so that the polymer layer and the liquid crystal layer intersect each other. Specifically, the boundary between the first polymer layer and the first liquid crystal layer and the boundary between the first polymer layer and the second liquid crystal layer, the first plane in contact with the convex surface of each curved portion constituting the boundary surface of the first polymer layer and the first liquid crystal layer The second plane in contact with the convex surface of each curved portion constituting the surface intersects. The angle formed between the first plane and one surface of the HPDLC layer 220 is substantially the same as the angle formed between the second plane and one surface of the HPDLC layer 220.

In the illuminating device of this embodiment, the periodic structures 221 and 222 have the operations described with reference to FIGS. 2B to 2D, similarly to the periodic structure of the HPDLC layer 12 in the illuminating device of the first embodiment.

Furthermore, as shown in FIG. 14, among the light incident on one surface of the HPDLC layer 220 from the light source 10 a via the light guide plate 11, the first polarized light 100 a is mainly transmitted by the periodic structure 221. Reflected in the direction of. Here, the incident angle of the light 100a on the concave surface of the periodic structure 221 satisfies the Bragg condition.

Of the light incident on one surface of the HPDLC layer 220 from the light source 10 b through the light guide plate 11, the first polarized light 100 b is reflected mainly by the periodic structure 222 in the direction of the light guide plate 11. Here, the incident angle of the light 100b on the concave surface of the periodic structure 222 satisfies the Bragg condition.

In this way, the periodic structure 221 is formed so that the concave surface is directed in the direction of the light source 10a, and the periodic structure 222 is formed so that the concave surface is directed in the direction of the light source 10b, whereby light from the light sources 10a and 10b is efficiently obtained. It can be reflected and emitted.

Of the light incident on the other surface of the HPDLC layer 220 from the light guide plate 13, light propagating in the direction from the light source 10a side to the light source 10b side is mainly diffused by the periodic structure 222, and from the light source 10b side to the light source 10a. The light propagating in the side direction is mainly diffused by the periodic structure 221. As described above, the convex surfaces provided in opposite directions can be efficiently diffused.

In the illumination device of the present embodiment, the emission condition and the angle conversion condition of the periodic structure 221 may be different from those of the periodic structure 222.

For example, when n = 1.55 (α ₁ <49.8 °), φ ₀ = ± 15 ° (φ ₁ = ± 9.6 °), and λ = 530 nm, light with α ₁ = 49 ° is emitted. The periodic structure 221 is configured such that the reflected light is reflected and emitted from the boundary surface between the HPDLC layer 220 and the light guide plate 11 at an emission angle of φ ₁ = 9.6 °. Further, the periodic structure 222 is configured to reflect light of α ₁ = 49 °, and the reflected light is emitted from the boundary surface between the HPDLC layer 220 and the light guide plate 11 at an emission angle of φ ₁ = 0 °. .

According to the above configuration, angles of 9.6 ° <φ ₁ <2.4 °, −1.3 ° <φ ₁ <1.3 °, and −9.6 ° <φ ₁ <−2.4 ° The light can be emitted in a range.

In the illuminating device of the present embodiment, the periodic structures 221 and 222 both satisfy the emission condition and the angle conversion condition, but one periodic structure may be configured to satisfy only the emission condition or the angle conversion condition. Good.

Next, a method for manufacturing the HPDLC layer of the lighting apparatus according to the third embodiment will be described.

FIG. 15 is a schematic diagram for explaining a method for producing the HPDLC layer. Also in the production of this HPDLC layer, the HPDLC precursor 100 shown in FIG. 10 is used. The laser beams 104 to 107 are P-polarized light or S-polarized light.

First, the laser beam 104 is irradiated from the substrate 101 side, and the laser beam 105 is irradiated from the substrate 102 side through the microlens 103 (first recording state). In the first recording state, the laser beam 104 is a reference beam, the laser beam 104 and the laser beam 105 incident through the microlens 103 are caused to interfere with each other, and the state (interference fringes) is caused to the HPDLC precursor 100. Record.

After stopping the irradiation of the laser beams 104 and 105, the laser beam 106 is irradiated from the substrate 101 side, and the laser beam 107 is irradiated from the substrate 102 side through the microlens 103 (second recording state). In this second recording state, the laser beam 106 is a reference beam, the laser beam 106 and the laser beam 107 incident through the microlens 103 are caused to interfere with each other, and the state (interference fringes) is made to the HPDLC precursor 100. Record.

The wavelength of the laser beams 104 to 107, the incident angle of the laser beams 104 to 107 to the HPDLC precursor 100, the shape of the convex surface of the microlens (curvature, etc.), etc. are appropriately set, and the first and second recording states are sometimes set. By switching by division, the liquid crystal molecules in the liquid crystal layer are aligned in one direction. Thereby, the HPDLC layer 220 shown in FIG. 13 can be formed.

When forming the HPDLC layer 120 shown in FIG. 11, in the manufacturing procedure shown in FIG. 13, the incident angles of the laser beams 106 and 107 to the HPDLC precursor 100 in the second recording state are set to the HPDLC layer 120. It is changed so as to correspond to the periodic structure 122 of FIG.

The lighting device of each embodiment described above is an example of the present invention, and the configuration thereof can be appropriately changed without departing from the spirit of the invention.

For example, in the illuminating device of the first embodiment, a prism surface 11a may be formed on the end surface of the light guide plate 11 as shown in FIG. The prism surface 11a is composed of a plurality of prism portions having a triangular cross section.

An angle θ formed by one side of the prism portion and the end surface of the light guide plate 11 (a surface parallel to the light emitting surface of the light source 10) is set to 7 °, for example. In this case, front emission from the light source 10 (emission in a direction perpendicular to the light emitting surface) is inclined by 5 ° with respect to the end face of the light guide plate 11 so as to be within the range of the angle α ₂ described above. Thereby, an optimum configuration (17.7 ° ≦ θ _r ≦ 23.4 °, d = 384.8 mm) for the second embodiment of the HPDLC layer can be provided.

The prism surface 11a shown in FIG. 16 may be applied to the illumination devices of the second and third embodiments. In this case, the prism surface 11a is formed on each end surface provided with the light sources 10a and 10b.

In the third embodiment, the light from the light source can be incident on the end face of the light guide plate 11 through the light guide plate. FIG. 17A and FIG. 17B show a modification of the illumination device of the third embodiment, FIG. 17A is a side view, and FIG. 17B is a plan view. 17A and 17B, the light guide plates 11 and 13, the HPDLC layer 12, and the quarter wavelength plate 14 are the same as those described in the third embodiment.

As shown in FIGS. 17A and 17B, light from the light sources 30a and 30b is supplied to one end surface of the light guide plate 11 via the prism light guide plate 31a, and light from the light sources 30c and 30d is supplied to the prism light guide plate 31b. To the other end face of the light guide plate 11.

The light source 30a is formed on one end face of the prism light guide plate 31a, and the light source 30b is formed on the other end face of the prism light guide plate 31a. The prism light guide plate 31 a has a prism portion for bending light supplied from both end faces in the direction of the end face of the light guide plate 11.

The light source 30c is formed on one end face of the prism light guide plate 31b, and the light source 30d is formed on the other end face of the prism light guide plate 31b. The prism light guide plate 31 b has a prism portion for bending light supplied from both end surfaces in the direction of the end surface of the light guide plate 11.

17A and 17B, the light from the four light sources 30a to 30d can be supplied to the light guide plate 11 without increasing the area of the exit surface of the quarter-wave plate 14. Therefore, the amount of light emitted from the exit surface of the quarter-wave plate 14 can be increased under the etendue constraint.

The configuration shown in FIGS. 17A and 17B can also be applied to the first and second embodiments. In the first embodiment, light sources 30 a and 30 b and a prism light guide plate 31 a are used on one end face of the light guide plate 11.

Further, in the illumination devices of the first to third embodiments, the HDLPC layer may have a periodic structure corresponding to each of the three primary colors of light, red, green, and blue. In this case, light sources (for example, LEDs) of red, green, and blue are provided as light sources. The HDLPC layer has a red periodic structure whose layer spacing corresponds to the wavelength of the red light source, a green periodic structure whose layer spacing corresponds to the wavelength of the green light source, and a blue layer whose layer spacing corresponds to the wavelength of the blue light source. And having a periodic structure. According to such a configuration, light (corresponding to white light) of predetermined polarized light (P-polarized light or S-polarized light) of red, green, and blue is emitted from the quarter wavelength plate 14.

The illumination device of the present invention described above can be applied to a projection display device represented by a liquid crystal projector.

FIG. 18 is a schematic diagram showing a configuration of a projection display device including the illumination device of the present invention. Referring to FIG. 18, the projection display device includes illumination devices 300 to 302, liquid crystal elements 303 to 305 as display elements, a cross dichroic mirror 306, and a projection optical system 307.

All of the lighting devices 300 to 302 are configured by any of the lighting devices of the above-described embodiments. A blue LED is used as the light source of the illumination device 300. A green LED is used as the light source of the illumination device 301. A red LED is used as the light source of the illumination device 302.

Although not shown in FIG. 18, there is another ¼ between the ¼ wavelength plate of the lighting device 300 (for example, the ¼ wavelength plate 14 shown in FIG. 1) and the liquid crystal element 303. A wave plate is provided. Similarly, another quarter wavelength plate is also provided between the quarter wavelength plate of the lighting device 301 and the liquid crystal element 304 and between the quarter wavelength plate of the lighting device 302 and the liquid crystal element 305. Is provided.

Another quarter wave plate may be provided in each of the lighting devices 300 to 302. In this case, each of the lighting devices 300 to 302 is provided with another quarter-wave plate so as to face the emission surface of the quarter-wave plate.

The blue light emitted from the illumination device 300 is applied to the liquid crystal element 303. The liquid crystal element 303 is driven by a liquid crystal driving circuit (not shown) and forms a blue image based on a video signal supplied from the outside.

The green light emitted from the illumination device 301 is applied to the liquid crystal element 304. The liquid crystal element 304 is driven by a liquid crystal driving circuit (not shown) and forms a green image based on a video signal supplied from the outside.

The red light emitted from the illumination device 302 is applied to the liquid crystal element 305. The liquid crystal element 305 is driven by a liquid crystal drive circuit (not shown), and forms a red image based on a video signal supplied from the outside.

The image light of each color formed by the liquid crystal elements 303 to 305 enters the projection optical system 307 via the cross dichroic mirror 306. The projection optical system 307 projects each color image formed by the liquid crystal elements 303 to 305 onto a screen (or a member replacing the screen) (not shown).

Another projection display device, as the illumination device of the present invention, emits light (corresponding to white light) of predetermined polarized light (P-polarized light or S-polarized light) of red, green and blue from the quarter-wave plate 14. Provided with a lighting device. Light emitted from the illumination device is irradiated onto a display element (for example, a liquid crystal element). The display element displays red, green, and blue images based on an external video signal in a time division manner. Each color image formed on the display element is projected by the projection optical system.

In the other projection display device described above, another quarter wavelength plate is provided between the illumination device and the display element (liquid crystal element). Another quarter wave plate may be provided in the lighting device. In this case, in the illumination device, another quarter wavelength plate is provided so as to face the emission surface of the quarter wavelength plate 14.

The illumination device of the present invention can be used as a backlight of a liquid crystal display in addition to the projection display device described above.

The present invention has been described above with reference to the embodiments, but the present invention is not limited to the above-described embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and operation of the present invention without departing from the spirit of the present invention.

For example, in the illumination device of each embodiment, the concave surface of each curved portion of the HPDLC layer is provided so as to face the light source side, but is not limited thereto. The concave surface of each curved portion faces the exit surface side, and the flat surface in contact with the concave surface of each curved portion, or the interface between the polymer layer of the HPDLC layer and the liquid crystal layer is the surface of the quarter wavelength plate (exit of the HPDLC layer) The concave surface of each curved portion may be provided in any way as long as the condition of inclining with respect to the surface-side light guide plate is satisfied.

FIG. 19 shows a configuration of a lighting device as a modification of the lighting device of the first embodiment, in which the direction of the concave surface of each curved portion is different from that of the lighting device of the first embodiment. In this modification, the concave surface of each curved portion of the HPDLC layer 12 faces the direction of the end surface located on the side opposite to the end surface where the light source 10a of the light guide plate 11 is provided. In FIG. 19, an arrow indicated by a solid straight line indicates P-polarized light, and an arrow indicated by a broken straight line indicates S-polarized light. Open arrows indicate unpolarized light including P-polarized light and S-polarized light.

As can be seen from the typical light path shown in FIG. 19, even in the configuration of this modified example, it is possible to obtain the same operational effects as those of the illumination device of the first embodiment.

Moreover, in the illumination device and the modification of each embodiment, the light source can be provided on one end face of the light guide plate 11, two opposite end faces, or each end face.

According to the present invention described above, the angular spread (outgoing angle) of the emitted light can be kept within the range where the light can be used based on the etendue restrictions, so that the light use efficiency can be improved.

Also, by making the boundary surface between the polymer layer and the liquid crystal layer of the holographic layer curved, the dependency on the incident angle of the hologram can be suppressed, so that the light utilization efficiency can be further improved.

Furthermore, the light propagating between the first and second light guide plates is diffused on the convex surface of the curved portion, and the light is circulated and used by performing polarization conversion through the quarter wavelength plate. Therefore, the light utilization efficiency can be further improved.

This application claims priority based on Japanese Patent Application No. 2009-281721 filed on Dec. 11, 2009, the entire disclosure of which is incorporated herein.

Claims (17)

1. At least one light source;
   A first light guide plate to which light emitted from the light source is supplied to an end surface;
   A quarter-wave plate provided on the first light guide plate;
   A holographic layer provided on a surface of the first light guide plate on a side opposite to the quarter-wave plate side;
   A second light guide plate that is provided on a surface of the holographic layer opposite to the first light guide plate side and returns light incident from the holographic layer to the holographic layer;
   The holographic layer is formed by alternately laminating a first liquid crystal layer in which liquid crystal molecules are aligned in one direction and a first polymer layer having a refractive index with respect to light having a predetermined polarization different from that of the first liquid crystal layer. Having a first periodic structure
   The first interface between the first polymer layer and the first liquid crystal layer is inclined with respect to the surface of the quarter-wave plate, the first interface is curved, and the curved portion The illumination device, wherein the concave surface side is located on the first light guide plate side.
2. The holographic layer includes a second liquid crystal layer in which liquid crystal molecules are aligned in one direction and a second polymer layer having a refractive index different from that of the second liquid crystal layer with respect to light having the predetermined polarization. A second periodic structure stacked;
   The second interface between the second polymer layer and the second liquid crystal layer intersects with the first interface of the first periodic structure, the second interface is curved, and the curved The lighting device according to claim 1, wherein a concave surface side of the portion is located on the first light guide plate side.
3. The lighting device according to claim 2, wherein the concave surfaces of the curved portions of the first and second periodic structures are both directed toward a predetermined end face side of the first light guide plate.
4. An output angle of light emitted from the quarter-wave plate is φ ₀ , and an incident angle of incident light incident on the holographic layer from the first light guide plate on the concave surfaces of the first and second periodic structures is θ ₁ , the complementary angle of the incident angle θ ₁ , α ₁ , and the holographic reflection light reflected from the concave surfaces of the first and second periodic structures toward the first light guide plate The angle with respect to the perpendicular drawn with respect to the boundary surface between the layer and the first light guide plate is φ ₁ , the angle between the first light guide plate of the reflected light and the boundary surface between the holographic layers is β ₁ , When the angle between the boundary surface of the holographic layer and the second light guide plate and the tangent at the incident point of the incident light of the concave surfaces of the first and second periodic structures is θ _r ,
   The first and second periodic structures are:
   

   

   Satisfying the emission conditions of
   An angle formed between the second light guide plate and a boundary surface of the holographic layer of light reflected at a point corresponding to the incident point of the convex surface of the curved portion of the first and second periodic structures. β ₂ , when the incident angle of light incident on the holographic layer from the second light guide plate at a point corresponding to the incident point of the convex surface is θ ₂ , and the complementary angle of the incident angle is α ₂ ,
   The first periodic structure further includes:
   

   

   The lighting device according to claim 2 or 3, wherein the angle conversion condition is satisfied.
5. When the refractive index of the holographic layer is n and the wavelength of the reflected light is λ,
   The layer interval d ₁ between the first liquid crystal layer and the first polymer layer is:
   

   

   Given in
   The layer interval d ₂ between the second liquid crystal layer and the second polymer layer is:
   

   

   The lighting device according to claim 4, which is given by:
6. An output angle of light emitted from the quarter-wave plate is φ ₀ , and an incident angle of incident light incident on the holographic layer from the first light guide plate on the concave surfaces of the first and second periodic structures is θ ₁ , the complementary angle of the incident angle θ ₁ , α ₁ , and the holographic reflection light reflected from the concave surfaces of the first and second periodic structures toward the first light guide plate The angle with respect to the perpendicular drawn with respect to the boundary surface between the layer and the first light guide plate is φ ₁ , the angle between the first light guide plate of the reflected light and the boundary surface between the holographic layers is β ₁ , When the angle between the boundary surface of the holographic layer and the second light guide plate and the tangent at the incident point of the incident light of the concave surfaces of the first and second periodic structures is θ _r ,
   The first periodic structure is:
   

   

   Satisfying the emission conditions of
   An angle formed between the second light guide plate and a boundary surface of the holographic layer of light reflected at a point corresponding to the incident point of the convex surface of the curved portion of the first and second periodic structures. β ₂ , when the incident angle of light incident on the holographic layer from the second light guide plate at a point corresponding to the incident point of the convex surface is θ ₂ , and the complementary angle of the incident angle is α ₂ ,
   The first and second periodic structures are:
   

   

   The lighting device according to claim 2 or 3, wherein the angle conversion condition is satisfied.
7. When the refractive index of the holographic layer is n and the wavelength of the reflected light is λ,
   The layer interval d ₁ between the first liquid crystal layer and the first polymer layer is:
   

   

   Given in
   The layer interval d ₃ between the second liquid crystal layer and the second polymer layer is:
   

   

   The lighting device according to claim 6, which is given by:
8. The light source is formed on each of the opposing end surfaces of the first light guide plate,
   The concave surface of the curved portion of the first periodic structure faces in the direction of one side of the opposing end surface;
   The lighting device according to claim 2, wherein the concave surface of the curved portion of the second periodic structure faces in the direction of the other side of the opposed end surfaces.
9. An output angle of light emitted from the quarter-wave plate is φ ₀ , and an incident angle of incident light incident on the holographic layer from the first light guide plate on the concave surfaces of the first and second periodic structures is θ ₁ , the complementary angle of the incident angle θ ₁ , α ₁ , and the holographic reflection light reflected from the concave surfaces of the first and second periodic structures toward the first light guide plate The angle with respect to the perpendicular drawn with respect to the boundary surface between the layer and the first light guide plate is φ ₁ , the angle between the first light guide plate of the reflected light and the boundary surface between the holographic layers is β ₁ , When the angle between the boundary surface of the holographic layer and the second light guide plate and the tangent at the incident point of the incident light of the concave surfaces of the first and second periodic structures is θ _r ,
   The first and second periodic structures are:
   

   

   Satisfying the emission conditions of
   An angle formed between the second light guide plate and a boundary surface of the holographic layer of light reflected at a point corresponding to the incident point of the convex surface of the curved portion of the first and second periodic structures. β ₂ , when the incident angle of light incident on the holographic layer from the second light guide plate at a point corresponding to the incident point of the convex surface is θ ₂ , and the complementary angle of the incident angle is α ₂ ,
   The first and second periodic structures further include:
   

   

   The lighting device according to claim 2 or 8, wherein the angle conversion condition is satisfied.
10. The refractive index of the holographic layer is n, the wavelength of the reflected light is λ, the layer interval between the first liquid crystal layer and the first polymer layer, and the second liquid crystal layer and the second polymer layer. When the layer spacing of both is d ₁ ,
    

    

    The lighting device according to claim 9, wherein the relationship is satisfied.
11. As the light source, a plurality of light sources having different colors of emitted light are provided,
    The lighting device according to claim 1, wherein the first periodic structure is provided for each color of the plurality of light sources.
12. As the light source, a plurality of light sources having different colors of emitted light are provided,
    The lighting device according to any one of claims 2 to 10, wherein the first and second periodic structures are provided for each color of the plurality of light sources.
13. The lighting device according to any one of claims 1 to 7, wherein the light source is formed on each of the opposing end surfaces of the first light guide plate.
14. The lighting device according to any one of claims 1 to 10, further comprising another quarter-wave plate on which light emitted from the quarter-wave plate is incident. .
15. The illuminating device according to claim 11 or 12, further comprising another quarter-wave plate on which light emitted from the quarter-wave plate is incident.
16. The lighting device according to any one of claims 11, 12, and 15,
    A display element irradiated with light emitted from the illumination device;
    A projection optical system that projects an image formed by the display element.
17. Claims 1 to 10, illuminating device of each color of red, green, and blue, comprising the illuminating device according to any one of claims 13 and 14, and
    A first display element irradiated with red light emitted from the red illumination device;
    A second display element irradiated with green light emitted from the green illumination device;
    A third display element irradiated with blue light emitted from the blue illumination device;
    A projection optical system that projects an image of each color displayed on the first to third display elements.

Images