JP2005129242A - Illumination device and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination device as a three-color mixture type backlight light source with no color unevenness and high brightness, and a transmission type image display device on which it is mounted. <P>SOLUTION: This is provided with light emitting LEDs 3, 4, and 5 to emit red, green and blue colors, a light proximity circuit 200 composed of a photonic crystal in which respective light emitting positions 209, 210, and 211 of red, green, and blue colors are converted into a proximity light arranged closely and are emitted, and a light guide plate 1 to emit a backlight light based on the proximity light emitted by the light proximity circuit 200. Instead of the light proximity circuit 200, this may be provided with an optical coupling circuit in which the red, green, and blue colors are coupled into one color by a directional coupling, and emitted as a coupled light. Furthermore, by branching the red, green, and blue colors respectively, they may be brought into proximity or coupled after making them a plurality of the red, green, and blue colors. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a three-color mixed illumination device serving as a backlight light source of a transmissive display, and a transmissive image display device such as a liquid crystal display or a liquid crystal television equipped with the illuminating device.

  In recent years, as an image display device, a thin display is expanding the market in place of a CRT that requires depth. There are PDP (Plasma Display Panel), a liquid crystal panel, etc. as a thin television. In particular, color LCD panels feature high-pixel technology based on semiconductors and low power consumption. Display screens for mobile phones / digital video cameras / digital still cameras, liquid crystal displays for personal computers, and liquid crystal televisions that replace TVs As such, it has been widely used. The liquid crystal panel does not emit light, and an image is produced by changing the amount of light transmitted through the backlight for each pixel. Therefore, the quality of the color reproducibility depends on how wide the chromaticity of the backlight is (see Non-Patent Document 1, for example). In general, in a cold cathode fluorescent tube used as a backlight of a liquid crystal panel, only a chromaticity range of about 70% of NTSC (National Television System Standard Committee) standard ratio can be obtained, whereas red (R), green (G), When a three-color mixture of blue (B) light emitting diodes (LEDs) is used, a color reproducibility as high as 95 to 130% of the NTSC standard ratio can be obtained. That is, an extremely vivid image can be obtained by RGB-LED three-color mixing.

  The basic backlight includes a light source and a light guide plate that guides the emitted light to illuminate the entire surface of the liquid crystal panel. A first conventional example of this backlight system is shown in FIG. 23 (for example, see Non-Patent Document 1). The illuminating device 920 shown in FIG. 23 performs three-color mixing by using the light of individual R, G, B-LEDs 305, 306, and 307 and reflection by mirrors 304 and 303. In this case, the light emitted from the respective LEDs 305, 306, and 307 is mixed through the mirror 304 and is emitted from the light guide plate 301 via the light guide plate 302 and the mirror 303.

  As a material of the light guide plate, acrylic resin is generally used. By forming fine irregularities on the reflective back surface (the surface that does not touch the liquid crystal panel) and scattering the light reflected from the inside of the light guide plate, the light is transmitted from the inside of the light guide plate to the outside (in the direction where the liquid crystal panel is located) Take out. The number of projections and depressions is about 500,000 to 5,000,000 pieces (size is 50 to 200 μm, height is 10 to 100 μm) on a 14-inch LCD.

Moreover, the 2nd prior art example is shown in FIG. 24 (for example, refer nonpatent literature 1). In the lighting device 921 in this conventional example, a configuration in which a plurality of R, G, B-LEDs 402, 403, and 404 mounted on a support base 405 are arranged as chips is attached to the side of the light guide plate 401 as a light source. I'm taking it.
Patent Document 1 discloses a method of shaving a part of a light guide plate and disposing an LED chip there.
JP 11-353920 A “Nikkei Electronics”, Nikkei Business Publications, no. 844, March 31, 2003, p.126-127

  The problem in RGB-LED three-color mixing is to mix colors uniformly. Since the light emission positions of the R, G, and B LEDs are different, even if they can be mixed to whiten the central portion, the surrounding area may be slightly red or blue, After color mixing, it looks like a slightly reddish white and a slightly bluish white. That is, there is a problem that color unevenness occurs and the quality of the displayed image is remarkably deteriorated. For this reason, a method of uniformly mixing three colors becomes important. In the first conventional example, the red, green, and blue LED light emission points 305, 306, and 307 are largely different, so that it is possible to roughly mix white, but it is difficult to whiten to the surroundings.

  On the other hand, in the second conventional example, a large number of chips 402, 403, and 404 are arranged without using a package (module) to achieve uniform three-color mixing. In this method, a large number of LED chips are mounted with high accuracy over several tens of centimeters. Further, for example, the technique disclosed in Patent Document 1 has a problem in that variations in the emission angle of LEDs cannot be suppressed, and color unevenness is likely to occur.

  Therefore, an object of the present invention is to provide an illumination device as a high-brightness three-color mixed type backlight light source without color unevenness, and an image display device equipped with the illumination device.

In order to achieve the above object, an illumination device according to the present invention is a three-color mixed illumination device that serves as a backlight light source of a transmissive image display device that displays an image, and has red, green, and blue colors. Light emitting means that emits light, and the red, green, and blue light emitted by the light emitting means are converted into proximity light in which the respective light emitting positions are close to each other and emitted, and the light proximity means that is emitted by the light proximity means And a light guide plate that emits backlight light based on the proximity light. Further, the proximity light is characterized in that the emission positions of the red, green and blue lights are close to each other within 10 μm. Further, the optical proximity means has a periodic refractive index changing structure.
Thereby, since the light emitting points in the light proximity means for emitting red, green, and blue light to the light guide plate can be regarded as substantially the same position, a white illumination device without color unevenness can be realized.

Further, the light proximity means emits two or more of the proximity lights.
Thereby, the white illuminating device without illuminance unevenness and color unevenness is realizable.
Further, the light proximity means splits the red, green and blue lights into a plurality of red, green and blue lights, respectively, and then each of the plurality of red, green and blue lights. One of the red, green, and blue light emission positions is converted into close proximity light and emitted.
As a result, even if there is only one light emitting means for emitting red, green and blue light, there are a plurality of light emitting points, and the three colors can be regarded as substantially the same position at each light emitting point. Thus, a white illumination device without color unevenness can be realized.

A three-color mixed type illumination device that serves as a backlight light source of a transmissive image display device that displays an image, the light emitting means for emitting red, green, and blue light, and the red, green, and blue light Are coupled to one light by directional coupling and output as combined light, and a light guide plate that receives the combined light emitted from the optical coupling means and emits backlight light. Features.
As a result, the light emitting point is completely at one position for the three colors, and an illumination device that does not cause any color unevenness can be realized.

Further, the optical coupling means emits two or more of the coupled lights.
Thereby, the white illuminating device without illuminance unevenness and color unevenness is realizable.
In addition, the optical coupling unit may branch the red, green, and blue light into a plurality of red, green, and blue lights, and then each of the plurality of red, green, and blue lights. One of the red, green, and blue lights is coupled to one light by directional coupling, and is emitted as coupled light.

  As a result, even if there is only one light emitting means, there are a plurality of light emitting points, and each light emitting point is completely in one position for the three colors, resulting in almost no illuminance unevenness and color unevenness. It is possible to realize a white lighting device without any problem.

A transmissive image display device that displays an image includes the illuminating device and transmissive display means on which backlight light emitted from the illuminating device is incident.
As a result, it is possible to realize a high-luminance and high-quality image display device that is extremely free of color unevenness.

  The lighting device of the present invention has no color unevenness and can realize a high-brightness three-color mixed lighting device. By using this lighting device, a personal computer, a digital video camera, a digital still camera, a liquid crystal monitor, a liquid crystal TV, etc. High image quality can be realized.

Hereinafter, embodiments of the present invention will be described more specifically with reference to the drawings.
(Embodiment 1)
FIG. 1 is a diagram showing a configuration of a lighting apparatus according to Embodiment 1 of the present invention. A lighting device 901 for a 13-inch liquid crystal display includes a plastic light guide plate 1 having a size of 20.5 cm in length and 27 cm in width, and light formed on a glass substrate on a side surface (short side) of the light guide plate 1. A branch circuit 2, a red light emitting diode 3, a green light emitting diode 4, and a blue light emitting diode 5 are provided.

  The optical branch circuit 2 is filled with a photonic crystal having a periodic refractive index change structure. As will be described later, a light waveguide can be formed by removing a periodic refractive index change of a part of the photonic crystal, and the red light waveguide 6 and the green light guide are formed in the optical branch circuit 2. A waveguide 7 and a blue light waveguide 8 are formed (for example, “O plus E”, New Technology Communications, vol. 25, No. 2 (2003) p. 191).

A red light emitting diode 3, a green light emitting diode 4, and a blue light emitting diode 5 are attached to the incident sides of the respective color waveguides 6, 7 and 8, and light emitted from the diodes 3, 4 and 5 is optically branched. It enters each incident part of the circuit 2. Each waveguide has two branches. In this figure, for simplicity, the two branches are repeated twice to branch one light input into four (= 2 ² ) light outputs with an equal amount of light. However, in practice, by repeating the bifurcation 10 times, one light input is branched to a 1024 (= 2 ¹⁰ ) light output with an equal amount of light. The light has 3 inputs of red, green and blue, so there are 3072 outputs in total.

  Each output terminal of the optical branch circuit 2 is configured by repeating a red output 9, a green output 10, and a blue output 11. Since the length per output is sufficiently fine such that 20.5 cm ÷ 3072≈67 μm, color unevenness due to differences in R, G, and B light emitting locations cannot be recognized by human eyes.

As a specific structural example of the waveguides 6, 7 and 8 in FIG. 1, a configuration diagram of a part 13 of the optical branching circuit 2 in FIG. 1 is shown in detail in FIG. A large number of aluminum nitride (AlN) 23 having a diameter of about 0.07 μm is embedded in silicon dioxide (SiO ₂ ) 21 with a period d = about 0.14 μm to form a photonic crystal 20.

  According to this configuration, the light forbidden band of the photonic crystal 20 includes all visible light. Further, a part of the photonic crystal 20 includes portions 23 and 24 where the photonic crystal is not formed. Because of the light forbidden band, light in the visible range cannot propagate through the photonic crystal 20, and therefore propagates through the portions 23 and 24 where the photonic crystal is not formed. In other words, the portions 23 and 24 where the photonic crystal is not formed are light waveguides in the visible range.

Further, the wavelength of light allowed in the waveguide is determined by the refractive index and the length of the waveguide width. Since the red, green, and blue waveguide widths are 5d, 4d, and 3d, respectively, they are 0.7, 0.56, and 0.42 μm, respectively. With this configuration, only red, green, and blue light propagate through the red, green, and blue waveguides, respectively.
Therefore, light can be selectively guided by changing the width of the red, green and blue waveguides. For example, in FIG. 2, when the photonic crystal interval is d, the width of the red waveguide 23 is 5d, and the width of the green waveguide 24 is 4d.

The red light incident on the red waveguide 23 is divided into two at the branching section 25. In the figure, the light directed upward changes its direction by 90 ° without loss at the bent portion 26 and is guided to the waveguide 28. Such a change in acute angle is a feature of the photonic crystal. On the other hand, light traveling downward in the figure intersects the green waveguide 24 at the intersection 27. However, since red light is not allowed in the green waveguide 24, the red light propagates downward as it is. It should be noted that the vertical direction is covered with SiO ₂ having a low refractive index characteristic so that light does not leak in the vertical direction of these waveguides.

FIG. 3 is a perspective view of the optical branch circuit 2 (photonic crystal) according to Embodiment 1 of the present invention. A large number of cylindrical AlN 121 is formed on the sapphire 120, and the AlN 121 is covered with SiO ₂ 123.

FIG. 4 is a diagram showing a method for manufacturing the optical branch circuit 2 (photonic crystal) according to Embodiment 1 of the present invention. First, as shown in FIG. 4A, a sapphire 120 substrate is prepared. Next, as shown in FIG. 4B, an AlN layer 121 is formed on the sapphire 120 substrate by MOCVD. Further, as shown in FIG. 4C, a plurality of photoresists 122 are formed on the AlN layer 121 by stepper or EB exposure. Next, as shown in FIG. 4D, the AlN layer 121 other than the lower part of the photoresist 122 is removed by dry etching. Subsequently, as shown in FIG. 4E, the resist 122 is removed by an asher. Finally, as shown in FIG. 4F, a SiO ₂ layer 123 is formed around and on the AlN 121 by CVD.

  FIG. 5 shows an external view of a liquid crystal display device 910 that combines the illumination device 901 according to Embodiment 1 of the present invention. On the illuminating device 901, the 1st polarizing plate 31, the liquid crystal panel 32 with a color filter, and the 2nd polarizing plate 33 are attached in order. Although these are shown as being separated in FIG. 5, they are actually in close contact. The first polarizing plate 31 and the second polarizing plate 33 have a so-called crossed Nicol arrangement in which the transmission polarization direction differs by 90 °.

  As the illuminating device 901, the optical branch circuit 2 is attached to the short side portion of the light guide plate 1, and the red LED 3, the green LED 4 and the blue LED 5 are attached to the side thereof. Since the photonic crystal can make the optical path an acute angle, a distance of 30 μm per branch is sufficient. Therefore, in this embodiment, since the light is divided into 10 branches, a width of 30 μm × 10 = 0.3 mm is sufficient. Actually, the size of the optical branch circuit 2 is set to 205 mm × 1 mm in order to include a connection portion with each LED 3, 4 and 5 and reinforcement.

  Red light, green light and blue light emitted from the red LED 3, green LED 4 and blue LED 5 are branched with almost no loss in the optical branch circuit 2 and become minute point light sources of 1024 points (× 3 colors) and are incident on the light guide plate 1. The In the light guide plate 1, the colors are mixed and become white with very little color unevenness. Since light is not confined in the vertical direction in the light guide plate 1, the light is guided upward and is first incident on the first polarizing plate 31. After being aligned in one polarization direction by the first polarizing plate 31, it is incident on the amorphous silicon TFT liquid crystal panel 32. A pigment color filter is attached to each pixel of the liquid crystal panel 32, and only a color necessary for each pixel is selected. In the liquid crystal panel 32, the light whose polarization angle is changed by a different amount for each pixel passes through the second polarizing plate 32, and finally an image is displayed.

  As described above, in the illuminating device according to the embodiment of the present invention, by repeating the branching a plurality of times, the energy is divided equally and the color unevenness of the backlight of the screen can be reduced. Further, red, green and blue light can be propagated only in the waveguide, and propagation loss can be reduced as compared with the conventional case.

(Embodiment 2)
In the second embodiment of the present invention, in order to prevent a slight propagation loss at the light crossing portion 27 in FIG. 2 in the optical branching circuit described in the first embodiment, the crossing portion has a two-layer structure. However, it is different.

  An example is shown in FIG. In FIG. 6, the two optical branch circuit layers 607 and 608 are shown apart, but are actually in contact. In the layer 607, red waveguides 601 and 602 and a green waveguide 603 are formed and are about to intersect. In the red waveguides 601 and 602, the formation of the waveguide is stopped by the light forbidden band in the vicinity of the intersection. ing. On the other hand, in the layer 608, the red waveguide 604 is formed so as to connect the two positions where the formation is stopped in the layer 607. With this two-layer configuration, the red light travels through the waveguide 601 in the layer 607 and then moves to the starting point of the waveguide 604 in the layer 608 adjacent thereto as shown in the moving direction 605. Then, after passing through the red waveguide 604 of the layer 608 without intersecting the green waveguide 603 of the layer 607, it moves to the waveguide 602 of the layer 607 at the end of the red waveguide 604 as indicated by the moving direction 606. . As a result, since red light and green light do not cross in the same waveguide, it is possible to prevent light propagation loss.

(Embodiment 3)
The third embodiment of the present invention differs from the optical branch circuit described in the first embodiment in that a three-layer structure is used to completely eliminate the light intersection.

FIG. 7 is a diagram showing the structure of the illumination device according to Embodiment 3 of the present invention. The lighting device 902 has a configuration in which a three-layer light branch circuit 114 on a glass substrate 115 is attached to the side of the light guide plate 1. FIG. 8 shows a state where the optical branch circuit 114 is disassembled in each layer.
The optical branch circuit 114 includes a red light branch circuit 111, a green light branch circuit 112, and a blue light branch circuit 113. Each of the optical branch circuits 111, 112, and 113 is configured using a photonic crystal. A red LED 3, a green LED 4, and a blue LED 5 are attached to each input section. The emission positions of the light branch circuits 111, 112, and 113 of the respective colors are set to the same position in the stacking direction. Each of the optical branch circuits 111, 112 and 113 is made of a thin film and has a thickness of 2 μm or less. Therefore, the light emission points of the respective colors can be regarded as the same position in practice, and color unevenness can be eliminated.

(Embodiment 4)
The fourth embodiment of the present invention is different in that the light guide plate described in the first embodiment is formed of a photonic crystal.

The block diagram of the illuminating device 903 which concerns on Embodiment 4 of this invention is shown in FIG. In FIG. 9, the light guide plate 41 and the light branch circuit 42 are formed on the same glass substrate to form a light guide plate 43 with a light branch circuit. The light guide plate 41 is also formed of a photonic crystal, and red, green, and blue waveguides 44, 45, and 46 are formed up to the end of the light guide plate 41. The number of branches of the optical branch circuit 42 is 4 outputs per color for the sake of simplicity in the figure, but in reality it is 8 branches, and 256 (= 2 ⁸ ) outputs per color. Accordingly, there are 256 × 3 = 768 outputs for the three colors, and the total number of waveguides 44, 45 and 46 in the light guide plate 41 is 768.

  FIG. 10 shows a specific structure of a part 47 of the connecting portion between the light guide plate 41 and the optical branch circuit 42 in FIG. Aluminum nitride 22 is embedded in silicon dioxide 21 to form photonic crystal 20. The photonic crystal 20 is designed so that all the light in the visible range is included in the light forbidden band (portions other than the waveguide and the vertical rising portion described later). No photonic crystal is formed in the waveguides 53 and 54, and the refractive index is constant. Unlike the waveguide of the optical branch circuit 42, places (photonic crystal defects) 51 and 52 without aluminum nitride exist in the vicinity of the waveguide of the light guide plate 41. Such defects in the photonic crystal function as a 90 ° vertical rise. Accordingly, a part of the guided light passing through the waveguides 53 and 54 is emitted in the photonic crystal defects 51 and 52 in a direction substantially perpendicular to the drawing, and functions as a light guide plate. With this configuration, the brightness is calculated to be about three times that of the conventional structure.

(Embodiment 5)
FIG. 11 shows a configuration of a liquid crystal display device 911 that combines the lighting device 903 and the liquid crystal panel 61 according to Embodiment 5 of the present invention. The basic configuration is similar to that shown in FIG. 5 described in the first embodiment, except that each color waveguide of the light guide plate 41 is assembled so as to correspond to each color pixel on the liquid crystal panel 61.

  That is, as shown in FIG. 12, the positions of the photonic crystal defects 51 and 52 from which light is extracted are aligned with the openings 71 and 72 of each pixel on the liquid crystal panel 61. As a result, there is no loss reflected by the light-shielding portion (portions other than the openings 71 and 72) of the liquid crystal panel 61, and a further increase in efficiency is possible. Since this improvement rate is improved by the aperture ratio in the direction parallel to the waveguide, the luminance in the configuration of FIG. 11 is further improved by about 1.5 times from the fourth embodiment (that is, 4.% in comparison with the prior art). 5 times).

Further, a color necessary for each color pixel on the liquid crystal panel 61 (for example, only red light is incident on the red pixel) is incident. Therefore, it is not necessary to attach a color filter to the liquid crystal panel 61. In the prior art, unnecessary light is absorbed by the color filter for color separation. However, since this is not necessary, the brightness is calculated to be about three times that of the prior art.
In order to ensure color separation, the liquid crystal panel 61 may naturally be provided with a color filter.

(Embodiment 6)
FIG. 13 shows the configuration of lighting apparatus 904 according to Embodiment 6 of the present invention. Although the basic configuration is similar to that of FIG. 9 showing the configuration of the illumination device 903 according to the fourth embodiment, the first branch portions 86, 87, and 88 as viewed from the incident side of the optical branch circuit 82 are used in this embodiment. The difference is that the polarization component (s wave and p wave) branches depending on the method described later.

The light emitted from each of the light-emitting diodes 3, 4 and 5 is non-polarized light, and the same amount of s wave and p wave is included. As a result, the upper half 84 of the light guide plate 81 in FIG. 13 can be separated into s-polarized light and the lower half 85 can be separated into p-polarized light.
FIG. 14 is a diagram illustrating a polarization branching unit and a state of polarization branching in the optical branching circuit 82 according to Embodiment 6 of the present invention. As shown in the figure, three rows of three-stage step-like photonic crystals 140 are formed as polarization branching portions. This photonic crystal 140 has a structure in which three rows of steps having a thickness of about 0.1 μm and a pitch of about 0.17 μm are arranged in three rows at a pitch of about 0.20 μm.

  The step-like photonic crystal 140 has a polarization separation function of transmitting a p-wave and reflecting an s-wave (see, for example, Electronics Lett. Vol. 35, no. 15, p. 1271 (1999)). The incident light is the sum of an s wave (TE wave) 130 and a p wave (TM wave) 131, and the p wave 131 passes through the stepped photonic crystal 140 and propagates as a p wave 133. On the other hand, since the s-wave 130 is reflected by the photonic crystal 140 that is installed at an angle of 45 °, the s-wave 130 changes its direction by 90 ° and propagates as the s-wave 132. As a result, the polarized light is separated and propagated.

  The step-like photonic crystal 140 can be manufactured by, for example, electron beam exposure. On the other hand, it is of course possible to use a photonic crystal having a polarization separation function of transmitting s waves and reflecting p waves.

  FIG. 15 shows an overall configuration of a liquid crystal display device according to Embodiment 6 of the present invention. In the liquid crystal display device 912, since the light emitted from the light guide plate 81 has already been polarized, a polarizing plate that is conventionally required between the liquid crystal panel 61 and the light guide plate 81 is not necessary. On the other hand, since the polarization directions are different between the upper half and the lower half of the screen, the polarizing transmission direction of the polarizing plate 93 on the liquid crystal panel 61 is 90 ° different between the upper half 91 and the lower half 92. In the conventional structure, half of the light is lost by the polarizing plate, but in the embodiment of the present invention, all light is used without loss, and a liquid crystal panel with extremely high luminance can be realized. . Also, with this configuration, the brightness is calculated to be about 9 times that of the conventional case.

  FIG. 16 is a diagram summarizing the relative comparison of the luminance improvement when the first, fourth, fifth, and sixth embodiments of the present invention are used. As can be seen from this figure, by using the present invention, not only color unevenness can be improved, but also the luminance can be increased to nearly 10 times in comparison with the prior art, and a vivid image can be displayed.

(Embodiment 7)
FIG. 17 is a diagram showing a configuration of an illumination apparatus according to Embodiment 7 of the present invention. The illumination device 905 according to the present invention is different in that a photonic crystal is used instead of light branching.

  In the illumination device 905, the optical proximity circuit 200 is provided beside the light guide plate 1. In the optical proximity circuit 200, the red, green, and blue waveguides 206, 207, and 208 are collected at an acute angle by the photonic crystal. A red LED 3, a green LED 4 and a blue LED 5 are attached to the incident side of each of the waveguides 206, 207 and 208. Due to the effect of the photonic crystal, the red, green, and blue emission points 209, 210, and 211 can be arranged in a very short interval (within about 10 μm). Here, the distance is about 3 μm. Therefore, red, green, and blue light guided in each waveguide can be regarded as light from substantially the same light emitting point, and color unevenness does not occur.

(Embodiment 8)
FIG. 18 is a diagram showing a configuration of a lighting apparatus according to Embodiment 8 of the present invention. The illumination device 906 has a configuration in which three rows of red, green, and blue waveguides 206, 207, and 208 are arranged in the optical proximity circuit 201. Thereby, the substantially same light emission point of red, green, and blue becomes three places, and the light guide plate 1 can be illuminated more uniformly. That is, the brightness unevenness is reduced as compared with the conventional case.

(Embodiment 9)
FIG. 19 is a configuration diagram of an illumination apparatus according to Embodiment 9 of the present invention. The illumination device 907 according to this embodiment is different in that the proximity of the three colors of light is further improved and combined (combined) by the optical coupling circuit 500.

  FIG. 20 is a diagram showing a state of optical coupling in the photonic crystal according to the ninth embodiment of the present invention, that is, a diagram showing the vicinity of the emission point of the optical coupling circuit 500 before entering the light guide plate 1 in FIG. is there. The red, green, and blue waveguides 501, 502, and 503 formed by the photonic crystal are in close contact with each other in the vicinity of the white light emitting portion 710 to form a directional coupler 505. The directional coupler 505 has such a property that when the distance between two waveguides becomes two gratings or less, light leaks to the adjacent waveguide and moves to the adjacent waveguide (for example, Akira Kawakami). Supervised by Jiro, "Photonic crystal technology and its application", CMC Publishing, published in March 2002, p.245). By this directional coupler 505, R, G, and B are combined into one white color, the light emission point becomes one, and the light is emitted from the white light emitting unit 710 and incident on the light guide plate 1, so that no color unevenness occurs. .

  Of course, a plurality of red LEDs 3, green LEDs 4, and blue LEDs 5 may be provided, and a plurality of white light emitting sections 710 may be provided using a plurality of directional couplers 505.

(Embodiment 10)
FIG. 21 is a configuration diagram of a lighting apparatus according to Embodiment 10 of the present invention. The lighting device 908 receives light of red, green, and blue in the light branching proximity circuit 700 and splits the light into a plurality of red, green, and blue lights, respectively, and then a plurality of red, green, and blue lights. 1 is different in that one of red, green, and blue light is made to approach each other, and a plurality of proximity lights are emitted at the emission ends 209, 210, and 211.

  Thereby, the illumination device according to Embodiment 10 of the present invention can realize the white backlight without color unevenness because the light emitting points of the light emitting elements that emit red, green, and blue light can be regarded as substantially the same.

(Embodiment 11)
FIG. 22 is a configuration diagram of a lighting apparatus according to Embodiment 11 of the present invention. The lighting device 909 receives red, green, and blue light in the light branching and coupling circuit 701 and branches them into a plurality of red, green, and blue lights, and then a plurality of red, green, and blue lights. 1 is different from the first embodiment in that combined light is formed by combining one red, green, and blue light, and a plurality of combined lights are emitted at the emission end 710.
As a result, the light emitting point is completely at one position for the three colors, and an illumination device that does not cause any color unevenness can be realized.

  In the first to eleventh embodiments described above, the optical branching circuit, the optical proximity circuit, the optical coupling circuit, the optical branching proximity circuit, and the optical branching coupling circuit that are configured with photonic crystals are arranged on the short side of the light guide plate. Although formed, of course, it may be formed on the long side. Of course, the material and structure of the photonic crystal may be other than those shown in the present embodiment. Of course, the light branching may be realized by three or more branches instead of two branches. Of course, proximity light or combined light may be formed with respect to the polarized light.

  The lighting device according to the present invention can realize a liquid crystal display with high brightness without color unevenness, and can be applied to a personal computer, a digital video camera, a liquid crystal monitor of a digital still camera, a liquid crystal TV, and the like.

It is a block diagram of the illuminating device which concerns on Embodiment 1 of this invention. It is a block diagram (part) of the optical branching circuit concerning Embodiment 1 of this invention. 1 is a perspective view of an optical branch circuit according to Embodiment 1 of the present invention. (A)-(f) is a figure which shows the manufacturing method of the optical branch circuit which concerns on Embodiment 1 of this invention. 1 is an overall view of a liquid crystal display according to Embodiment 1 of the present invention. It is a figure which shows the mode of the intersection of the light in the optical branch circuit which concerns on Embodiment 2 of this invention. It is a block diagram of the illuminating device which concerns on Embodiment 3 of this invention. It is an exploded view of the illuminating device which concerns on Embodiment 3 of this invention. It is a block diagram of the illuminating device which concerns on Embodiment 4 of this invention. It is a block diagram (part) of the illuminating device which concerns on Embodiment 4 of this invention. It is a general view of the liquid crystal display which concerns on Embodiment 5 of this invention. It is a figure which shows the relationship between the light-guide plate which concerns on Embodiment 5 of this invention, and the pixel opening of a liquid crystal display. It is a block diagram of the illuminating device which concerns on Embodiment 6 of this invention. It is a figure which shows the mode of the polarization branch part and polarization branch in the optical branch circuit which concerns on Embodiment 6 of this invention. It is a general view of the liquid crystal display which concerns on Embodiment 6 of this invention. It is a figure which shows the luminance comparison at the time of using the illuminating device which concerns on Embodiment 1, 4-6 of this invention. It is a block diagram of the illuminating device which concerns on Embodiment 7 of this invention. It is a block diagram of the illuminating device which concerns on Embodiment 8 of this invention. It is a block diagram of the illuminating device which concerns on Embodiment 9 of this invention. It is a block diagram of the optical coupling circuit which concerns on Embodiment 9 of this invention. It is a block diagram of the illuminating device which concerns on Embodiment 10 of this invention. It is a block diagram of the illuminating device which concerns on Embodiment 11 of this invention. It is sectional drawing of the conventional illuminating device (1st example). It is a block diagram of the conventional illuminating device (2nd example).

Explanation of symbols

1, 301, 302, 401 Light guide plate 2, 42 Optical branch circuit 3, 305, 402 Red LED
4, 306, 403 Green LED
5,307,404 Blue LED
6, 23, 28, 44, 206, 501, 601, 602, 604 Red waveguide 7, 24, 45, 53, 207, 502, 603 Green waveguide 8, 46, 54, 208, 503 Blue waveguide 9, 209 Red emitting part 10, 210 Green emitting part 11, 211 Blue emitting part 13 Part of optical branch circuit 20 Photonic crystal 21, 123 SiO ₂
22, 121 AlN
25 Red branch portion 26 Red bent portion 27 Crossing portion of red waveguide and green waveguide 31, 33 Polarizing plate 32 Color filter liquid crystal panel 41, 81 Light guide plate with waveguide 43 With waveguide integrated with optical branch circuit Light guide plate 47 Part of connecting portion of optical branch circuit and light guide plate with waveguide 51, 52 Photonic crystal defect (vertical rising part)
61 Liquid Crystal Panel Without Color Filter 71, 72 Pixel Opening of Liquid Crystal Panel 82 Polarization Separation Type Optical Branch Circuit 83 Waveguide Light Guide Plate Integrated with Polarization Separation Type Optical Branch Circuit 84 Polarization Display Unit 85 Polarization Display Unit (Polarization Display Unit 84) Different polarization direction)
86 Red polarized light separating unit 87 Green polarized light separating unit 88 Blue polarized light separating unit 91 Polarizing plate 92 Polarizing plate (polarization direction different from polarizing plate 91)
93 Polarizing plate in which polarizing plates 91 and 92 are integrated 111 Red light branching circuit 112 Green light branching circuit 113 Blue light branching circuit 114 Laminated light branching circuit 115 Glass substrate 120 Sapphire 122 Photoresist 130, 132 s wave (TE wave)
131, 133 p wave (TM wave)
140 Polarization Separator 200, 201 Optical Proximity Circuit 303, 304 Mirror 405 Support Base 500 Optical Coupling Circuit 505 Directional Coupler 605, 606 Movement Direction of Red Waveguide to Adjacent Layer 607, 608 Optical Waveguide Circuit Layer 700 Optical Branching Proximity circuit 701 Optical branching and coupling circuit 710 White light emitting portion 901, 902, 903, 904, 905, 906, 907, 908, 909, 920, 921 Illumination device 910, 911, 912 Liquid crystal display device

Claims (10)

A three-color mixed illumination device that serves as a backlight source of a transmissive image display device that displays an image,
A light emitting means for emitting red, green and blue light;
Light proximity means for converting the red, green, and blue light emitted by the light emitting means into proximity light that is close to the respective light emitting positions and emitting the light.
An illumination device comprising: a light guide plate that emits backlight light based on the proximity light emitted by the light proximity means. The illuminating device according to claim 1, wherein the proximity light is close to a light emission position of the red, green, and blue light within 10 μm. The lighting device according to claim 1, wherein the light proximity unit emits two or more pieces of the proximity light. The lighting device according to any one of claims 1 to 3, wherein the optical proximity unit has a periodic refractive index change structure. The light proximity means splits the red, green and blue light into a plurality of red, green and blue lights, respectively, and then one of each of the plurality of red, green and blue lights. The illumination device according to any one of claims 1 to 4, wherein the red, green, and blue light is converted into near-field light in which light emission positions are close to each other and emitted. A three-color mixed illumination device that serves as a backlight source of a transmissive image display device that displays an image,
A light emitting means for emitting red, green and blue light;
Optical coupling means for coupling the red, green, and blue light to one light by directional coupling and emitting the coupled light;
An illumination device comprising: a light guide plate that receives the combined light emitted from the optical coupling unit and emits backlight light. The lighting device according to claim 6, wherein the optical coupling unit emits two or more of the coupled lights. The lighting device according to claim 6 or 7, wherein the optical coupling means has a periodic refractive index change structure. The light coupling means splits the red, green, and blue lights into a plurality of red, green, and blue lights, respectively, and then one of each of the plurality of red, green, and blue lights. The lighting device according to any one of claims 6 to 8, wherein the red, green, and blue lights are coupled to one light by directional coupling and emitted as coupled light. A transmissive image display device that displays an image,
The lighting device according to any one of claims 1 to 9,
An image display device comprising: transmissive display means on which backlight light emitted from the illumination device is incident.

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