JP5254583B2 - Light distribution device and backlight device using the same - Google Patents

Description

  The present invention relates to a light distribution device and a backlight device using the same.

  As an application example of a light distribution device that gives a desired directivity by controlling the direction of light emitted from a light source, for example, a backlight device (hereinafter simply referred to as a liquid crystal display (LCD)) or the like. Also called “backlight”. The liquid crystal display itself is indispensable for many electronic devices such as personal computers and mobile phones as a display device in the IT era. In the present specification, hereinafter, a transmissive liquid crystal display (LCD) and a transmissive LCD panel that require a backlight are simply referred to as “liquid crystal display (LCD)” and “LCD panel”.

  FIG. 21 is a schematic sectional view showing a general structure of a conventional liquid crystal display, and FIG. 22 is a schematic plan view showing a surface structure of the LCD panel of FIG.

  As shown in FIG. 21, the conventional liquid crystal display 1 is generally composed of an LCD panel 10 and a backlight 20. The LCD panel 10 regularly arranges the liquid crystal cells 13 and the color filters 14 between the two glass substrates 11 and 12, and one on each of the surfaces of the two glass substrates 11 and 12. It has a structure in which a single polarizing sheet (also called a polarizing film or a polarizing film) 15 and 16 is attached. The backlight 20 is normally a white light source that emits white light including three primary color components of red (R), green (G), and blue (B) (hereinafter abbreviated as “RGB”). There are three types of color filters 14, a red (R) color filter 14 a, a green (G) color filter 14 b, and a blue (B) color filter 14 c, depending on the color of light to be transmitted. Each liquid crystal cell 13 has a light opening / closing function and is controlled by a control element (transistor or the like) (not shown). One liquid crystal cell 13 constitutes one pixel.

  In this structure, the white light 30 emitted from the backlight 20 is irradiated to the entire surface on the back side of the panel. The irradiation light passes through the polarizing sheet 15 and the liquid crystal cell 13, and passes through any of the RGB color filters 14a to 14c. One pixel is formed by mixing the intensity of RGB light transmitted through the color filters 14a to 14c. In other words, one pixel is constituted by the three liquid crystal cells 13 corresponding to the set of RGB color filters 14a to 14c.

  Irradiation light from the backlight 20 passes through the liquid crystal cell 13 but does not pass through other than the liquid crystal cell 13. Therefore, the area of the liquid crystal cell 13 becomes the light transmission area 17, and the area other than the liquid crystal cell 13 becomes the light non-transmission area 18. The light transmission region 17 includes a red (R) light transmission region 17a, a green (G) light transmission region 17b, and a blue (B) light transmission region 17c according to the color of the transmitted light. The light 31 irradiated to the light non-transmissive region 18 other than the opening (light transmissive region 17) is absorbed and causes energy loss. For example, in the case of a general TFT panel, since the panel aperture ratio is about 50%, the light non-transmissive region 18 is about 50% of the entire area, and the light energy is accompanied by a loss of about 50%.

  In addition, the conventional backlight 20 usually uses white light. White light includes RGB color components of the three primary colors. In the conventional liquid crystal display 1, the three color filters 14a to 14b of RGB are irradiated with white light, the colors other than the corresponding color are blocked, and only the corresponding color is transmitted through the surface of the LCD panel 10, thereby achieving the target Getting color. For example, a portion of the liquid crystal cell 13 corresponding to red (R) in one pixel (red light transmission region 17a) is also irradiated with white light including RGB spectrum at the same time, but the color of red (R) Only the red (R) spectral portion becomes transmitted light by the filter 14a. At this time, the original light energy (light energy applied to the light transmission region 17a) loses 2/3 light energy. This situation is the same when the light color components are green (G) and blue (B).

  As described above, in the case where the conventional backlight 20 is used, in the light transmission region 17, 2/3 of the entire spectrum of white light transmitted through the polarizing sheet 15 is blocked in principle. Therefore, in this case, the light applied to the light transmission region 17 loses 2/3 of its light energy. From this, the light energy efficiency that is effectively utilized for the light after passing through the polarizing sheet 15 including the light energy loss in the light non-transmissive region 18 is about 1/6 (= 1/2 × 1 / Only 3). In the case of a general liquid crystal display, the light energy transmittance is about 8%, and the light energy loss by the polarizing sheet is about 50%. Therefore, the substantial light energy efficiency excluding the light energy loss by the polarizing sheet is 16% (about 1/6). This figure shows that the above analysis is valid.

  As described above, in the conventional liquid crystal display 1, the light energy loss in the light non-transmissive region 18 and the light energy loss when transmitted through the color filter 14 are large, and the substantial light energy efficiency (polarizing sheet) that is effectively used. (Excluding light energy loss due to) is only about 1/6. Therefore, a large amount of energy is required to ensure display brightness. In particular, in recent years, backlights using RGB light emitting diodes (LEDs) (generally referred to as “LED backlights”) have begun to be used in liquid crystal displays, and such liquid crystal displays have the advantage of color vividness. Is allowed. However, since such a liquid crystal display also has low light energy efficiency, a large number of LEDs are used to ensure luminance. For this reason, a large amount of heat is generated. Therefore, in the liquid crystal display using the LED backlight, there is a strong demand for solving the problem of heat energy release (heat radiation) as well as the problem of loss of light energy.

  For example, a large LCD television (LCD-TV) uses about several thousand LEDs. The LEDs are evenly arranged on the front surface of the backlight. An existing backlight with light sources (LEDs) distributed on the surface requires an electronic circuit that controls the balance of the emission intensity of each LED to ensure uniformity in chromaticity and brightness. is there. For this reason, a huge number of LED control circuits are required. For this reason, as the existing LED backlight becomes larger, the more the number of LEDs increases, the more difficult it is to manufacture. As a result, LED backlights are expensive. For these reasons, there is a strong demand for LED backlights to improve light energy efficiency and reduce the number of LEDs.

In this regard, as a technique for improving the utilization efficiency of light energy, for example, it is known to use a prism sheet for the backlight to efficiently direct the light of the backlight in the normal direction (for example, Patent Document 1). . The prism sheet is configured by arranging a plurality of prisms in a row on one side of the base film. This prism sheet has a function of concentrating light on the surface to increase the front luminance. In other words, the prism sheet effectively utilizes light by condensing the light and directing it to the front.
JP 2006-330672 A

  However, even in a backlight using a prism sheet, a color filter is indispensable as long as white light is used for the backlight, and light energy loss during transmission of the color filter is inevitable. Even when a prism sheet is used, the backlight itself emits surface light, and thus light energy loss in the light non-transmissive region is unavoidable. Therefore, there is a certain big limit in improving the utilization efficiency of light energy.

  It should be noted that improving the utilization efficiency of light energy is not limited to a backlight, but is a request that is widely demanded by light distribution devices in general.

  This invention is made | formed in view of this point, and it aims at providing the light distribution apparatus which can improve the utilization efficiency of optical energy significantly, and a backlight apparatus using the same.

  The light distribution device of the present invention includes a linear light guide that guides light in one direction using total reflection, and light that is disposed on the light guide and travels through the light guide while repeating total reflection. And a light distribution path that distributes light in a predetermined target direction using reflection.

  The backlight device of the present invention employs a configuration having the light distribution device described above.

  According to the present invention, the utilization efficiency of light energy can be greatly improved.

  In particular, when the light distribution device of the present invention is used in a backlight device such as a liquid crystal display, the light energy utilization efficiency in the backlight device can be dramatically improved. Specifically, the utilization efficiency of light energy in the backlight device can be reduced to a theoretical value of about 50% (only light energy loss due to the polarizing sheet). That is, for example, the efficiency can be improved by about 6 times compared to the case where a prism sheet is used.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing a schematic configuration of a liquid crystal display including a backlight device using the light distribution device according to Embodiment 1 of the present invention.

  The liquid crystal display 100 shown in FIG. 1 is roughly composed of a backlight unit 200 and an LCD panel unit 300. The backlight unit 200 irradiates the liquid crystal in the LCD panel unit 300 from the back side, and has the spectral separation structure according to the present invention. Specifically, the backlight unit 200 includes a light source unit 210, a light incident unit 220, a linear light guide unit 230, a normal light distribution unit 240, and a condenser lens unit 250. Note that a backlight having a spectral separation structure according to the present invention is referred to as a “spectral separation type backlight” in comparison with a conventional backlight having a normal structure.

  The light source unit 210 has a function of generating light of a single color. Specifically, the light source unit 210 splits white light to generate light of a predetermined color (for example, RGB), or uses a light emitting diode (LED) of a predetermined color (for example, RGB). The light of the predetermined color is generated. White light is provided by, for example, natural light (sunlight), a white lamp, a white LED, or the like.

  The light incident unit 220 has a function of guiding light of each color (for example, RGB) generated by the light source unit 210 to the linear light guide unit 230. Specifically, the light incident unit 220 causes light of each color (for example, RGB) generated by the light source unit 210 to enter the interior of the linear light guide corresponding to each color at an angle that allows total reflection. It has a function. As will be described later, the linear light guide unit 230 includes a plurality of linear light guides.

  The linear light guide unit 230 has a light guide with a linear structure (hereinafter referred to as “linear light guide”) corresponding to each color (for example, RGB) generated by the light source unit 210. This linear light guide has a function of guiding light of a corresponding color in one direction using total reflection. As will be described in detail later, the linear light guides are optically separated from each other, and are formed, for example, by printing on a substrate. Moreover, the linear light guide is arrange | positioned according to the light irradiation position to the exterior. For example, the linear light guide is disposed in the LCD panel unit 300 where the light of the corresponding color should be transmitted, that is, below the light transmission region of the corresponding color. As a result, the light of each color is guided directly below the light transmission region of the corresponding color.

  The normal light distribution unit 240 distributes the light guided by the linear light guide unit 230 in the normal direction of the backlight unit 200 (that is, the LCD panel unit 300), and transmits light in the LCD panel unit 300. It has a function to pass through. As will be described in detail later, the normal light distribution unit 240 has a normal light distribution path disposed on the linear light guide. In the normal light distribution path, the light traveling through the linear light guide path while repeating total reflection is transmitted in a predetermined target direction (here, the light passes through a target light transmission region in the LCD panel unit 300, It has a function of distributing light in the backlight unit 200, that is, the normal direction of the LCD panel unit 300.

  The condensing lens unit 250 condenses the light emitted from the normal light distribution unit 240 using a condensing lens for the purpose of passing through a minute light transmission region (such as a liquid crystal cell) in the LCD panel unit 300. It has the function to do. In addition, the condensing lens part 250 is not necessarily an indispensable component, and the condensing lens part 250 is unnecessary when condensing property is not required.

  The LCD panel unit 300 is basically the same as the conventional LCD panel 10 (see FIG. 21). However, as will be described later, the LCD panel unit 300 according to the present embodiment can remove the color filter 14 from the conventional LCD panel 10 due to its structure.

  Next, a specific structure of the backlight unit (spectral separation type backlight) 200 will be described in detail with reference to the drawings.

  FIG. 2 is a schematic perspective view showing an example of the configuration of the spectrally separated backlight. 3 is a schematic cross-sectional view showing an example of the structure of a liquid crystal display using the spectrally separated backlight shown in FIG. 2, and FIG. 4 is a schematic plan view showing the surface structure of the LCD panel portion of FIG. It is.

  A spectrally separated backlight (hereinafter simply referred to as “backlight”) 200 a illustrated in FIG. 2 includes an RGB light emitting diode (LED) 211 as the light source unit 210. Specifically, the backlight 200a includes, as the light source unit 210, a red (R) LED 211a, a green (G) LED 211b, and a blue (B) LED 211c. The light of each color emitted from the RGB LEDs 211a to 211c is guided to the linear light guide unit 230 through the corresponding light incident paths 221a, 221b, and 221c.

  The backlight 200 a includes a plurality of linear light guides 231 as the linear light guide unit 230. As described above, the linear light guide 231 has a function of guiding light of a corresponding color in one direction using total reflection. The red (R) light emitted from the red (R) LED 211a is guided to the red (R) linear light guide 231a through the light incident path 221a. The green (G) light emitted from the green (G) LED 211b is guided to the green (G) linear light guide 231b through the light incident path 221b. The blue (B) light emitted from the blue (B) LED 211c is guided to the blue (B) linear light guide path 231c through the light incident path 221c. The plurality of linear light guides 231a to 231c are optically separated from each other.

  Further, the backlight 200 a includes a plurality of normal light distribution paths 241 as the normal light distribution unit 240. As described above, the normal light distribution path 241 distributes the light traveling inside the linear light guide 231 while repeating total reflection in a predetermined target direction (here, the normal direction of the backlight 200a). It has a function. The normal light distribution path 241 is disposed on the linear light guide path 231. The red (R) light traveling inside the red (R) linear light guide 231a is distributed by the red (R) normal light distribution path 241a and emitted in the normal direction of the backlight 200a. . The green (G) light traveling inside the green (G) linear light guide 231b is distributed by the green (G) normal light distribution path 241b and emitted in the normal direction of the backlight 200a. . The blue (B) light traveling inside the blue (B) linear light guide 231c is distributed by the blue (B) normal light distribution path 241c and emitted in the normal direction of the backlight 200a. .

  The light incident path 221, the linear light guide path 231, and the normal light distribution path 241 all have the same refractive index in visible light because light propagates through the interior due to total reflection. Therefore, basically, the light incident path 221, the linear light guide path 231, and the normal light distribution path 241 are formed using, for example, the same component resin, preferably an ultraviolet curable resin. The ultraviolet curable resin is generally constituted by blending a prepolymer, a monomer, a photoinitiator, a sensitizer, a colorant, and various additives. When UV curable resin is irradiated with UV (UV light), the photoinitiator inhales UV to initiate photopolymerization reaction, and converts monomers and prepolymers to polymers to form a network-like cross-linked structure. . When an ultraviolet curable resin is used, it is preferable that the surrounding substance (medium) 270 in contact with the light incident path 221, the linear light guide path 231, and the normal light distribution path 241 is, for example, an inert gas such as air or nitrogen. . However, the type of gas is not limited to this. Basically, any gas can be used since the refractive index of the gas is around 1.0.

  Preferably, the linear light guide 231 is formed by printing on a transparent sheet substrate 260, for example, and the normal light distribution path 241 is formed by printing on the linear light guide 231. The linear light guide path 231 and the normal light distribution path 241 are formed using a known screen printing method including the light incident path 221, for example. An example of a specific manufacturing method will be described in detail later.

  3 and 4 show the positional relationship among one pixel of the LCD panel 310, the linear light guide path 231 and the normal light distribution path 241. FIG. As shown in FIGS. 3 and 4, the linear light guide 231 extends linearly under the light irradiation position to the outside, specifically, the light transmission region 317 of the corresponding color in the LCD panel 310. Are arranged. For example, the red (R) linear light guide 231a is disposed under a plurality of red (R) light transmission regions 317a arranged on a straight line, and the green (G) linear light guide 231b is The blue (B) linear light guides 231c are arranged under a plurality of green (G) light transmission regions 317b arranged on a straight line, and the blue (B) linear light guide paths 231c are arranged on a straight line. It arrange | positions under the light transmissive area | region 317c. Further, the normal light distribution path 241 on the linear light guide path 231 is also disposed under the light irradiation position to the outside, specifically, the corresponding color light transmission region 317 in the LCD panel 310. For example, the normal light distribution path 241a for red (R) is disposed under the light transmission region 317a for each red (R), and the normal light distribution path 241b for green (G) is provided for each green (G ) And the blue (B) normal light distribution path 241c are arranged under the individual blue (B) light transmission regions 317c.

  With this configuration, the light of each color is guided directly below the light transmission region 317 of the corresponding color. For example, the red (R) light passes through the red (R) linear light guide 231a and is guided directly below the red (R) light transmission region 317a. The red (R) light guided directly below the red (R) light transmission region 317a is emitted in the normal direction of the backlight 200a by the normal light distribution path 241a for red (R). The red (R) light 130a emitted in the normal direction of the backlight 200a passes only through the red (R) light transmission region 317a, and the light non-transmission region 318 and green (G) and blue (B) light. The light is not emitted to the light transmission regions 317b and 317c. Similarly, the green (G) and blue (B) emission lights 130b and 130c also pass only through the corresponding color light transmission regions 317b and 317c. As a result, it is possible to eliminate the light energy loss in the light non-transmissive region and the light energy loss when transmitted through the color filter, which are the major causes of the light energy loss in the conventional liquid crystal display.

  3 has a basic configuration similar to that of the conventional LCD panel 10 shown in FIG. Specifically, the LCD panel 310 regularly arranges the liquid crystal cells 313 between the two glass substrates 311 and 312, and one on each of the surfaces of the two glass substrates 311 and 312. It has a structure in which a sheet of polarizing sheets 315 and 316 are attached. However, the LCD panel 310 does not require a color filter necessary for the conventional LCD panel 10. Also in this case, each liquid crystal cell 313 has a light opening / closing function, and is controlled by a control element (such as a transistor) not shown. The point that one pixel is constituted by three liquid crystal cells 313 is the same as that of the conventional LCD panel 10.

  FIG. 5 is a diagram for explaining the principle of light propagation in the spectrally separated backlight shown in FIGS. 3 and 4.

  The light emitted from the LED 211 of any color is guided to the corresponding linear light guide 231 through the corresponding light incident path 221. The light 110 entering the linear light guide 231 from the light input path 221 propagates through the interior of the linear light guide 231 by total reflection. Here, total reflection refers to perfect reflection without energy loss at the refractive index interface (reflectance = 100%). For example, when the linear light guide 231 is formed of an ultraviolet curable resin and the surrounding medium is air, the critical angle is such that there is no refracted light with respect to incident light (only reflected light), as will be described later. Is about 42 °. Therefore, the light 110 propagating through the linear light guide 231 by total reflection propagates at an inclination angle within about ± 48 ° (= 90 ° -42 °) from the horizontal direction. The light 110 propagating through the inside of the linear light guide 231 has an inclination angle from 0 ° to 48 ° at the contact surface (boundary surface) 280 between the linear light guide 231 and the normal light distribution path 241. The light having the light enters the normal light distribution path 241. The light 120 incident on the normal light distribution path 241 from the linear light guide path 231 propagates through the normal light distribution path 241 by total reflection, and finally, from the upper surface of the normal light distribution path 241, It is emitted in the normal direction. That is, the light 130 emitted from the normal light distribution path 241 is obtained by distributing the light 110 in the linear light guide path 231 in the normal direction of the backlight 200a.

  Note that light propagating by total reflection does not leak to the outside, so that the linear light guide 231 looks transparent when viewed from the outside. The same applies to the light incident path 221 and the normal light distribution path 241. However, the light 130 emitted from the normal light distribution path 241 can be visually recognized. In light transmission, being visible from the outside means loss of light energy.

  FIG. 6 is a diagram for explaining the principle of total reflection.

According to Snell's law (the law of refraction), the incident angle from the medium A to the medium B is θ ₁ , the refraction angle from the medium A to the medium B is θ ₃ , the absolute refractive index of the medium A is n _A , and the medium B When the absolute refractive index of n is n _B , the following relationship holds.
sin θ ₁ / sin θ ₃ = n _B / n _A
Here, the absolute refractive index is a relative refractive index specific to a substance with respect to vacuum in a light wave. At the critical angle (θ ₃ = 90 °), which is the maximum incident angle at which refraction occurs, there is no refracted light and only reflected light. From the above formula, it can be seen that the magnitude of the critical angle is determined by the refractive index of the medium. When n _A > n _B and light enters the medium B from the medium A, the critical angle θ _m (incident angle from the medium A to the medium B) is as follows.
sin θ _m = sin θ _m / sin 90 ° = n _B / n _A
Therefore, for the incident angle θ ₁ from the medium A to the medium B,
θ ₁ > θ _m
Satisfying this relationship is a condition for total reflection. Note that, according to the law of reflection, the incident angle θ ₁ and the reflection angle θ ₂ of the light reflected by the boundary surface (reflecting surface) are equal (θ ₁ = θ ₂ ).

For example, when the medium A is an ultraviolet curable resin and the medium B is air, the absolute refractive index of the ultraviolet curable resin is about 1.5 and the absolute refractive index of air is about 1.0. Therefore, the critical angle θ _m is sin θ _{From m} = 1.0 / 1.5, θ _m = 41.8103 °, which is about 42 °. Accordingly, light incident at a critical angle (about 42 °) or more, that is, light incident at an angle of about 48 ° or less with respect to the boundary surface is all reflected light (total reflection).

  In this embodiment, the principle of total reflection, specifically, for example, when light is incident on the air from an ultraviolet curable resin, all light incident within a horizontal angle of about ± 48 ° is at the boundary surface. The principle of total reflection and propagation in the traveling direction is used for the propagation of light in a light guide printed on a plane.

  Usually, light propagating through the linear light guide 231 is absorbed and scattered by the material and impurities forming the light guide, and gradually attenuates. Factors of attenuation include factors such as the optical characteristics of the medium through which light propagates and the surface uniformity of the light guide. For example, in an ultraviolet curable resin, the intensity of propagating light is attenuated by about 10% per meter. Therefore, the intensity of propagating light is attenuated in proportion to the distance from the light source. And the brightness | luminance of the light radiate | emitted from a backlight changes according to the attenuation characteristic of propagation light.

  Therefore, in this embodiment, for example, the contact area between the linear light guide path 231 and the normal light distribution path 241 (the area of the contact surface 280) is changed to eliminate the luminance change due to the attenuation characteristic. That is, as described above, a part of the light 110 propagating through the linear light guide 231 enters the normal light distribution path 241 from the contact surface 280 between the linear light guide 231 and the normal light distribution path 241. . The amount of light entering the normal light distribution path 241 is proportional to the area of the contact surface 280. Therefore, by utilizing this, the luminance difference can be eliminated by adjusting the area of the contact surface 280. Specifically, the area of the contact surface 280 is adjusted so that the amount of light entering the normal light distribution path 241 from the contact surface 280 is equal for all the contact surfaces 280. For example, the area of the contact surface 280 is increased as the distance from the light source increases in accordance with the attenuation characteristics of light propagating through the linear light guide 231.

  Next, the light incident path 221 will be described in more detail.

  FIG. 7 is a schematic plan view showing a main part of a spectrally separated backlight using RGB LEDs in the present embodiment. FIG. 8 is a schematic cross-sectional view showing a main part of a spectrally separated backlight using RGB LEDs in the present embodiment. FIG. 8A shows the case where the height of the LED is higher than the height of the linear light guide, and FIG. 8B shows the case where the height of the LED is lower than the height of the linear light guide.

  As described above, the light incident path 221 enters the linear light guide path 231 from the LED 211 so that the light of the RGB LEDs 211 is totally reflected inside the corresponding linear light guide path 231 as described above. It has a function of adjusting the angle of the light beam.

  Specifically, the radiation angle distribution of the light emitted from the RGB LEDs 211 largely depends on the shape of the LEDs. However, in recent years, the radiation angle distribution of LEDs has been kept within about ± 30 °. The function of the light incident path 221 is to guide the light of the LED 211 to the linear light guide 231 within a horizontal angle of about ± 48 °. However, the shape of the LED 211 and the shape of the entrance (light incident surface) of the linear light guide 231 are usually different. Therefore, the light incident path 221 has a shape that effectively guides the light from the LED 211 to the linear light guide path 231 according to the difference. Although the specific shape of the light incident path 221 is determined by simulation using geometric optics on the premise of total reflection, it is necessary to consider the radiation angle distribution of the LED 211. Specific examples of the shape of the light incident path 221 are as shown in FIGS. 7 and 8, for example. Note that when determining the shape of the light incident path 221, it is not necessary to consider the refraction of light, and thus it is not necessary to perform individual adjustment for each color.

  Next, the normal light distribution path 241 will be described in more detail.

  FIG. 9 is a schematic cross-sectional view showing a specific example of the shape of the normal light distribution path. In particular, FIG. 9A shows the simplest configuration example, FIG. 9B shows an example configuration having an ideal shape, and FIG. Show.

  As described above, the normal light distribution path 241 transmits light traveling through the linear light guide path 231 while repeating total reflection, in a predetermined target direction (here, a target light transmission region 317 in the LCD panel unit 300). Has a function of distributing light in the normal direction of the backlight 200a so that the light passes through. Although the principle of light distribution in the normal direction by the normal light distribution path 241 will be described in detail later, the normal light distribution path 242 shown in FIG. 9A has the simplest configuration (shape). is there. Specifically, the normal light distribution path 242 is, for example, in one stage in which the front reflection surface is inclined by 45 ° with respect to the light propagation direction in the linear light guide 231 and the rear reflection surface is inclined by 30 °. Each is formed in only one stage.

  Here, the angle of the rear reflecting surface can be determined as follows. First, the tilt of the rear reflective surface must be less than 48 °. This is because, at an angle of 48 ° or more, the propagation light of the linear light guide 231 is not applied to the rear reflecting surface. For example, when the inclination is 30 ° as described above, the light having a traveling angle of 48 ° is reflected by the rear reflecting surface and travels in the direction of 12 °, and further reflected by the front reflecting surface and the direction of 78 °. Proceed to That is, the light traveling at a traveling angle of 48 ° changes in the traveling direction to 78 ° by two reflections. The optimum angle of the rear reflecting surface depends on the angular distribution of the propagation light in the linear light guide 231. However, if the angle is too small, the height of the normal light distribution path 241 becomes too low, making it difficult to adjust the amount of light. Therefore, practically, an angle in the vicinity of 20 ° to 30 ° is preferable.

  A normal light distribution path 243 illustrated in FIG. 9B has an ideal shape. The ideal shape is a parabola. Actually, since the starting points of light entering the normal light distribution path 243 are distributed on the line of the opening (here, the contact surface 280), the midpoint of the opening (contact surface 280) is used as a virtual light source. It is practical to design the shape of the line light distribution path 243. In the example shown in FIG. 9B, the normal light distribution path 243 has, for example, a front reflective surface sequentially inclined at 45 °, 55 °,... With respect to the light propagation direction in the linear light guide 231. The rear reflecting surface is formed in multiple stages where the inclination sequentially changes to 60 °,... That is, in the normal light distribution path 243 shown in FIG. 9B, the front reflection surface and the rear reflection surface are formed in multiple stages as shapes that approximate a parabola.

  Here, the reason why the ideal shape of the normal light distribution path 243 is a parabola is as follows. As shown in FIG. 10A, when the curve C is a parabola with the point F as the focal point, when the light emitted from the focal point F is reflected by the curve C, all the light is reflected in the normal direction. The That is, the light of the point light source that emerges from the focal point of the parabola is reflected in the normal direction. When this principle is applied to this embodiment, it is as follows. Consider the case where the focal point F of the parabola C is placed at the midpoint of the opening (contact surface 280) as shown in FIG. In this case, the light 121 emitted from the position of the focal point F is reflected in the normal direction by the above principle. On the other hand, light 121 and 123 emitted from a position that is on the line of the opening (contact surface 280) but not the focal point F is reflected with a deviation from the normal direction. Therefore, if the normal light distribution path 243 is designed so as to have a minute contact surface 280 at the position of the focal point F of the parabola C, the light 130 emitted from the normal light distribution path 243 is emitted almost in the normal direction. Will be. That is, when the shape of the normal light distribution path 243 is a parabola, the smaller the contact surface 280 between the linear light guide path 231 and the normal light distribution path 243, the smaller the dispersion of the angle in the normal direction. In this case, it is necessary to mask portions other than the minute contact surface 280 so that light is not transmitted.

  A normal light distribution path 244 shown in FIG. 9C is a configuration example of an intermediate level between the normal light distribution path 242 in FIG. 9A and the normal light distribution path 243 in FIG. 9B. Compared to the normal light distribution path 243 of (B), the shape can be realized relatively easily. Specifically, the normal light distribution path 244 is inclined with respect to the light propagation direction in the linear light guide path 231, for example, the front reflective surface is inclined in two stages of 45 ° and 60 °, and the rear reflective surface is inclined. It is formed in two stages of 20 ° and 90 °, respectively.

  The angular distribution of the emitted light from the normal light distribution path 241 varies depending on the shape of the normal light distribution path 241. That is, the normal light distribution paths 242 to 244 described above have different angular distributions of emitted light.

Since the normal light distribution path 241 has a fine three-dimensional structure as described above, it is preferable to provide the protective sheet 245 in order to protect the upper surface of the normal light distribution path 241. The protective sheet 245 is a transparent resin sheet having a thickness of about several tens of microns (μm), for example. Also,
For example, the protective sheet 245 can be formed using an ultraviolet curable resin in a step different from the step of forming the normal light distribution path 241.

  Here, the principle of light distribution in the normal direction by the normal light distribution path 241 will be described with reference to the drawings. FIG. 11 is a diagram showing the angular distribution of light propagating through the linear light guide. FIG. 12 is a diagram for explaining the principle of light distribution in the normal direction by the normal light distribution path.

  As described above, the propagating light 110 in the linear light guide path 231 is totally reflected and partially enters the normal light distribution path 241 if the inclination is within ± 48 ° with respect to the horizontal direction. The light is emitted from the light distribution path 241 in the normal direction of the backlight 200a. At this time, the propagation light 110 of the linear light guide 231 has a light intensity distribution close to a Gaussian distribution in an angular range of ± 48 °, as shown in FIG. In FIG. 12, for convenience, the angle is 45 °. The propagation light 110 of the linear light guide 231 having such a distribution is a contact surface (boundary surface) 280 between the linear light guide 231 and the normal light distribution path 241 and a part thereof (that is, 0 ° to 48 °). Light having an inclination angle of up to 5) enters the normal light distribution path 241. At this time, as described above, the amount of incident light is proportional to the area of the contact surface 280. The light 120 incident on the normal light distribution path 241 from the linear light guide path 231 propagates through the normal light distribution path 241 by total reflection, and finally, from the upper surface of the normal light distribution path 241, It is emitted in the normal direction. That is, the light 130 emitted from the normal light distribution path 241 is obtained by distributing the light 110 in the linear light guide path 231 in the normal direction of the backlight 200a. At this time, in the simplest configuration, the shape of the normal light distribution path 241, for example, the inclination angle of the front reflecting surface with respect to the light propagation direction in the linear light guide 231 is the angle of the propagation light 110 in the linear light guide 231. An optimum angle of 48 ° or less may be determined in consideration of the distribution. In the example of FIG. 12, it is 45 degrees.

  The shape of the normal light distribution path 241 may be a more complicated shape in consideration of the efficiency of the propagation light 120 in the normal light distribution path 241. A specific example is the shape shown in FIGS. 9B and 9C. In particular, FIG. 9B shows a parabolic shape when more light is reflected in the normal direction.

  Furthermore, how to determine the shape of the normal light distribution path 241 (design concept, standard) will be described with reference to FIG.

  First, in FIG. 13A, the propagation light 110 of the linear light guide path 231 has a traveling angle distribution of ± 48 °, and light of 0 ° to 48 ° enters the normal light distribution path 241. Here, let us consider changing the traveling direction of this light to the normal direction. Considering the angular distribution of the propagating light 110, the light intensity in the vicinity of 0 ° is maximum as described above (see FIG. 11). Therefore, in order to change light having a traveling angle of 0 ° in the normal direction (90 ° direction) by total reflection, the light is incident on a reflecting surface having an inclination angle of 45 ° with respect to the traveling direction. There is a need. At this time, the propagation direction of the propagation light having the traveling angle θ is changed in the direction of (90 ° −θ) by the reflection surface having the inclination angle of 45 °. At this time, the angular distribution of the light 130 emitted in the normal direction is in a range of 42 ° to 90 °. The actual emission angle is, for example, propagating light having an angle of 20 ° is emitted in the direction of 30 ° according to the law of refraction. Actual emitted light is distributed in the range of 0 ° to 90 °. However, in the actual propagating light 110, since the cross-sectional area of the reflecting surface with respect to the propagating light with the angle of 0 ° is small, the contribution ratio of the propagating light with the angle of 0 ° with respect to all the outgoing light is not the maximum, and the propagating light with the angle of about 15 ° It is considered that the contribution ratio of is the largest.

Thus, in the actual propagating light 110, the cross-sectional area of the reflecting surface with respect to the propagating light with an angle of 0 ° is small, and the contribution ratio of the propagating light with the angle of 0 ° with respect to all the outgoing light is not the maximum. Although it depends on the angular distribution of the propagating light 110, it is considered that the propagating light having an angle of about 15 ° is the largest in the contribution ratio to the total emitted light. In order to reflect the propagating light of this angle in the normal direction (90 ° direction), from the following formula:
2 * α-θ = 90 °
θ = 15 °
∴α = 52.5 °
It becomes. In reality, it is a tuning parameter, but considering the symmetry of the normal direction of the emitted light, and considering the angle of the reflecting surface to reflect to about 95 °,
2 * α-θ ° = 95 °
θ = 15 °
∴α = 55 °
It becomes. Therefore, as shown in FIG. 13B, the two-step inclined angle reflecting surface is more efficiently produced by the linear light guide 231 than the single angle reflecting surface shown in FIG. 13A. The propagating light 110 can be emitted in the normal direction. In this case, the angle emitted from the upper surface of the normal light distribution path 241 is determined according to the law of refraction.
1.5 * sin (5 °) = 1.0 * sin (θ)
∴θ = 7.5 °
Therefore, it is emitted in the direction of 97.5 °.

  Next, the manufacturing method of the linear light guide path 231 and the normal light distribution path 241 is demonstrated using drawing. FIG. 14 is a cross-sectional view for each process showing an example of a method for manufacturing the linear light guide 231. FIG. 15 is a cross-sectional view for each process showing an example of a method for manufacturing the normal light distribution path 241. Here, for the sake of simplification, the case where the normal light distribution path 242 having the simplest configuration (shape) shown in FIG. 9A is manufactured as the normal light distribution path 241 will be described as an example. Here, as an example, a case where the linear light guide path 231 and the normal light distribution path 241 are manufactured using, for example, screen printing will be described.

  First, the case where the linear light guide 231 is formed (printed) on the transparent sheet substrate 260 by screen printing will be described with reference to FIG.

  First, as shown in FIG. 14A, an aluminum foil sheet 290 for forming the pattern of the linear light guide path 231 is prepared, and an ultraviolet transmission pattern portion (cutout) is formed on the aluminum foil sheet 290 for the linear light guide path pattern. Part) 291. Specifically, for example, the linear light guide path pattern aluminum foil sheet 290 is cut out in accordance with the pattern shape of the linear light guide path 231 by a YAG laser engraving machine. The linear light guide pattern aluminum foil sheet 290 preferably has such a thickness that the thickness can be ignored, for example, a thickness of about several tens of microns (μm).

  Then, as shown in FIG. 14 (B), after the aluminum foil sheet 290 for linear light guide pattern in FIG. 14 (A) is installed on the sheet substrate 260, the aluminum foil sheet 290 for linear light guide pattern is cut out. The portion 291 is filled with a liquid ultraviolet curable resin 292.

  And as shown in FIG.14 (C), an ultraviolet-ray (UV light) is irradiated from a normal line direction. Thereby, the ultraviolet curable resin 292 in the cutout portion 291 is cured, and the pattern of the linear light guide 231 is formed.

  Then, as shown in FIG. 14D, the linear light guide pattern aluminum foil sheet 290 on the sheet substrate 260 is removed. Thereby, the pattern of the linear light guide 231 is printed on the sheet substrate 260.

  Next, the case where the normal light distribution path 241 is formed (printed) on the linear light guide path 231 by screen printing will be described with reference to FIG.

  First, as shown in FIG. 15A, an aluminum foil sheet 295 for forming a pattern of the normal light distribution path 241 is prepared, and an ultraviolet transmission pattern portion (cutout) is formed on the aluminum foil sheet 295 for the normal light distribution path pattern. Part) 296. Specifically, for example, the normal light distribution path pattern aluminum foil sheet 295 is cut out in accordance with the pattern shape of the normal light distribution path 241 with a YAG laser engraving machine. The normal light distribution path pattern aluminum foil sheet 295 preferably has a thickness such that the thickness thereof can be ignored, for example, a thickness of about several tens of microns (μm).

  Then, as shown in FIG. 15B, a liquid ultraviolet curable resin 297 is filled and applied to a predetermined thickness on the sheet substrate 260 on which the pattern of the linear light guide 231 is printed. At this time, the normal light distribution path pattern aluminum foil sheet 295 of FIG. 15A is installed on the liquid ultraviolet curable resin 297. Thereafter, in this state, for example, ultraviolet rays (UV light) are irradiated from the direction inclined by 60 ° from the normal direction toward the transparent substrate sheet 298 for manufacturing on the back surface of the aluminum foil sheet 295 for the normal light distribution path pattern. . The ultraviolet rays pass through the cutout portion 296 and reach the liquid ultraviolet curable resin 297. Thereby, only the part 241a irradiated with ultraviolet rays is cured in the liquid ultraviolet curable resin 297.

  Then, as shown in FIG. 15C, this time, by changing the irradiation angle of the ultraviolet rays, for example, from the direction inclined 45 ° from the normal direction, the back surface of the aluminum foil sheet 295 for the normal light distribution path pattern The transparent substrate sheet 298 for manufacturing is irradiated with ultraviolet rays (UV light). This ultraviolet ray passes through the cutout portion 296 and reaches the liquid ultraviolet curable resin 297 in another region. As a result, the portion of the ultraviolet curable resin 297 corresponding to the pattern of the normal light distribution path 241 is finally cured, and the pattern of the normal light distribution path 241 is formed.

  Then, as shown in FIG. 15D, the normal light distribution path pattern aluminum foil sheet 295 is removed, and the non-cured resin, that is, the remaining liquid ultraviolet curable resin 297 is washed and removed. Thereby, the pattern of the normal light distribution path 241 is printed on the pattern of the linear light guide path 231.

  In addition to the screen printing technique described above, an inkjet printing technique, an offset printing technique, or the like can be used as a printing method using an ultraviolet curable resin. That is, any printing technique may be used as long as it can form a fine three-dimensional structure on the sheet by changing the irradiation angle of the ultraviolet rays a plurality of times and curing it. When printing technology is used, there is an advantage that it can be manufactured in large quantities at a low cost, but in addition to this, for example, using techniques such as photolithography, sputtering, etching, etc. used for manufacturing LSI etc., linear There exists an advantage that a light guide part can be manufactured. In particular, for the method of forming the linear light guide 231, it is possible to use a general plastic molding technique in addition to the above printing technique.

  Thus, according to the present embodiment, the linear light guide path 231 and the normal light distribution path 241 are provided so that the light from the light source unit 210 can be distributed in the normal direction (desired direction) for each color. Therefore, the utilization efficiency of light energy can be significantly improved.

  In particular, when applied to a backlight for a liquid crystal display, eliminate the light energy loss in the light non-transmission region and the light energy loss when transmitting the color filter, which are the major causes of light energy loss in the conventional liquid crystal display. And the utilization efficiency of light energy can be reduced to a theoretical value of about 50% (only light energy loss by the polarizing sheet). This is, for example, an improvement in efficiency of about 6 times compared to the case where a prism sheet is used. That is, it is possible to pass the light energy of the light source unit 210 of the backlight unit 200 through the surface of the liquid crystal display most efficiently, and there is no loss other than the loss of 50% which is the energy loss by the polarizing sheet. Light can be realized.

  Moreover, the color filter of the existing liquid crystal display can be removed, and the cost of the liquid crystal display can be reduced and further energy efficiency can be improved.

  In addition, with the improvement of the utilization efficiency of light energy, for example, a constant luminance can be ensured with a smaller number of LEDs, and the number of LEDs used for the backlight can be suppressed. As a result, it is possible to reduce power consumption and solve the problem of heat dissipation.

(Embodiment 2)
The second embodiment is a case where the condenser lens unit 250 is provided.

  FIG. 16 is a schematic cross-sectional view showing an example of the structure of a liquid crystal display using a backlight device (spectral separation type backlight) using the light distribution device according to Embodiment 2 of the present invention. The liquid crystal display 100b has a basic configuration similar to that of the liquid crystal display 100a corresponding to the first embodiment shown in FIG. 3, and the same components are denoted by the same reference numerals, and the description thereof is omitted. Omitted.

  In this embodiment, a TFT panel 310a is used as the LCD panel 310, and RGB color filters 314a, 314b, and 314c are provided in the RGB light transmission regions 317a to 317c, respectively. In this example, the thickness of the glass substrate 311 of the TFT panel 310a is about 500 microns (μm), whereas the RGB light transmission regions 317a to 317c are each about 100 microns (μm). Therefore, the light emitted from the normal light distribution path 241 is collected by the condenser lens 251 and passes through the light transmission region 317. Specifically, red (R) light emitted from the normal light distribution path 241a for red (R) is condensed by the condenser lens 251a and passes through the red (R) light transmission region 317a. The green (G) light emitted from the normal light distribution path 241b for green (G) is condensed by the condenser lens 251b and passes through the green (G) light transmission region 317b. The blue (B) light emitted from the blue (B) normal light distribution path 241c is condensed by the condenser lens 251c and passes through the blue (B) light transmission region 317c. As a result, the light use efficiency of the LCD panel 310 (TFT panel 310a) having a minute light transmission region can be further improved. In FIG. 16, reference numeral “400” denotes a diffusion sheet.

  The condenser lens 251 can be printed in a lens shape, for example, on the polarizing sheet 315 by using an inkjet printing technique using an ultraviolet curable resin as an ink. Moreover, the manufacturing method of the condensing lens 251 is not necessarily limited to an inkjet printing technique, Arbitrary appropriate manufacturing methods can be applied. For example, screen printing technology, plastic molding technology, optical molding technology, etc. can be applied.

  As described above, according to the present embodiment, the condensing lens 251c is provided and the light emitted from the normal light distribution path 241 is condensed, so that a fine light transmission region can be passed. As a result, for example, the light utilization efficiency of the LCD panel 310 (TFT panel 310a) having a minute light transmission region can be further improved.

(Embodiment 3)
The third embodiment is a case where the light source unit 210 has a white light source. In other words, the present embodiment is a case where the light source unit 210 generates light of a predetermined color (for example, RGB) by splitting white light.

  FIG. 17 is a schematic cross-sectional view showing an example of the structure of a liquid crystal display using a backlight device (spectral separation type backlight) using the light distribution device according to Embodiment 3 of the present invention. FIG. 18 is a schematic cross-sectional view showing the main part of the backlight device (spectral separation type backlight) of FIG. The liquid crystal display 100c has a basic configuration similar to that of the liquid crystal display 100b corresponding to the second embodiment shown in FIG. 16, and the same components are denoted by the same reference numerals, and the description thereof is omitted. Omitted.

  In the present embodiment, the white light 140 emitted from the white light source 212 is guided to the light incident unit 500. The light incident section 500 distributes the white light 140 from the white light source 212 in a sheet shape, branches it, splits the branched white light into RGB colors by a prism, and linear light guide sections 231a corresponding to the respective colors. ˜231c has a function of entering light. Therefore, the light incident unit 500 includes a white light distribution unit 510, a condensing lens unit 520, a light shaping / spectral unit 530, and a light distribution unit 540. In FIG. 17, for the sake of convenience, the linear light guide path 231 and the normal light distribution path 241 are collectively denoted by reference numeral “235” in FIG. The white light 140 may be sunlight.

  The white light distribution unit 510 propagates the white light 140 using total reflection. The condensing lens unit 520 branches a part of the white light 140 propagating through the white light distribution unit 510 and focuses the branched light on the light shaping unit (aspheric concave lens) 531 of the light shaping / spectral unit 530. Condensate to tie. The condensing lens portion 520 includes a portion 521 having a parabolic shape and an aspherical convex lens 522. The light shaping unit (aspheric concave lens) 531 of the light shaping / spectral unit 530 converts the light from the condensing lens unit 520 into a small beam of parallel light, and the spectral unit 532 of the light shaping / spectral unit 530. Send to. The spectroscopic unit 532 of the light shaping / spectral unit 530 decomposes the parallel light rays into RGB spectra by the spectroscopic prism. The light distribution units 540a to 540c guide the decomposed light of each color to the corresponding linear light guides 231a to 231c.

  Such a micro-optical system is difficult to configure with conventional three-dimensional lenses and prisms, but can be easily realized by using a printing technique such as screen printing to form a flat surface. Can do.

  Thus, according to the present embodiment, since white light is used, ambient light such as sunlight can be used, and a light distribution device and a backlight that do not use electric energy can be provided. It becomes possible.

  It should be noted that several modifications can be considered for this embodiment.

  19 and 20 are diagrams showing an example of the modification. The liquid crystal display 100d shown in FIGS. 19 and 20 has the same basic configuration as the liquid crystal display 100c shown in FIGS. 17 and 18, and the same components are denoted by the same reference numerals and the description thereof will be given. Is omitted.

  In this modification, the structure of the condensing lens part 610 which comprises the light-incidence part 600 is different. In this structure, since the white light 140 distributed in the white light distribution unit 510a is collected by the reflecting function of the condensing lens unit 610, the white light 140 is reflected on the curved surface of the condensing lens unit 610. The surface is mirror-reflected.

  The light distribution device according to the present invention and the backlight device using the light distribution device are useful as a light distribution device and a backlight device that can significantly improve the utilization efficiency of light energy.

The block diagram which shows schematic structure of the liquid crystal display containing the backlight apparatus using the light distribution apparatus which concerns on Embodiment 1 of this invention. Schematic perspective view showing an example of a configuration of a spectrally separated backlight in the present embodiment Schematic sectional view showing an example of the structure of a liquid crystal display using the spectrally separated backlight shown in FIG. Schematic plan view showing the surface structure of the LCD panel portion of FIG. The figure for demonstrating the light propagation principle in the spectral separation type backlight shown in FIG. 3 and FIG. Diagram for explaining the principle of total reflection Schematic plan view showing the main part of a spectrally separated backlight using RGB LEDs in the present embodiment It is a schematic sectional drawing which shows the principal part of the spectral separation type backlight using RGB LED in this Embodiment, (A) is a figure which shows the case where the height of LED is higher than the height of a linear light guide. (B) is a figure which shows the case where the height of LED is lower than the height of a linear light guide. It is a schematic sectional drawing which shows the specific example of the shape of the normal light distribution path in this Embodiment, (A) is a figure which shows the simplest structural example, (B) is a structural example which has an ideal shape. The figure to show, (C) is a figure which shows the example of a structure of the intermediate level of both (A) is a diagram for explaining the reason why the shape of the parabola is ideal, and (B) is a diagram for explaining the case where the principle is applied to the present embodiment. The figure which shows the angle distribution of the light which propagates a linear light guide Diagram for explaining the principle of light distribution in the normal direction by the normal light distribution path Diagram for explaining how to determine the shape of the normal light distribution path Sectional drawing according to process which shows an example of the manufacturing method of a linear light guide Sectional drawing according to process which shows an example of the manufacturing method of a normal light distribution path Schematic sectional view showing an example of the structure of a liquid crystal display using a backlight device (spectral separation type backlight) using a light distribution device according to Embodiment 2 of the present invention Schematic sectional view showing an example of the structure of a liquid crystal display using a backlight device (spectral separation type backlight) using a light distribution device according to Embodiment 3 of the present invention FIG. 17 is a schematic cross-sectional view showing the main part of the backlight device (spectral separation type backlight) of FIG. Schematic sectional view showing a modification of the backlight device (spectral separation type backlight) of FIG. Schematic sectional view showing the main part of the backlight device (spectral separation type backlight) of FIG. Schematic sectional view showing the general structure of a conventional liquid crystal display FIG. 21 is a schematic plan view showing the surface structure of the LCD panel of FIG.

Explanation of symbols

100, 100a, 100b, 100c, 100d Liquid crystal display (LCD)
110, 120 Propagating light 130 Emission light 140 White light 200 Backlight unit 200a Spectral separation type backlight 210 Light source unit 211a, 211b, 211c LED
212 White light source 220, 500, 600 Light incident part 221a, 221b, 221c Light incident path 230 Linear light guide part 231a, 231b, 231c Linear light guide path 240 Normal light distribution part 241a, 241b, 241c, 242, 243, 244 Normal light distribution path 250 Condensing lens unit 251a, 251b, 251c Condensing lens 260 Sheet substrate 270 Air 280 Contact surface 300 LCD panel unit 310 LCD panel 311, 312 Glass substrate 313 Liquid crystal cell 314a, 314b, 314c Color filter 315, 316 Polarizing sheets 317a, 317b, 317c Light transmission region 318 Light non-transmission region 400 Diffusion sheet 510, 510a White light distribution portion 520, 610 Condensing lens portion 521 Parabolic shape portion 522 Aspheric convex lens 530 Light shaping / spectral portion 53 1 Light shaping part (aspheric concave lens)
532 Spectrometer 540a, 540b, 540c Light distributor

Claims (18)

A linear light guide that guides light in one direction using total reflection;
A light distribution path that is disposed on the light guide path and distributes light traveling through the light guide path in a predetermined target direction using total reflection, the light distribution path extending in the light guide path and the predetermined target direction. When the surface along both of the directions is a cross section, among the reflection surfaces constituting the light distribution path, at least the light distribution path in which the cross-sectional shape of the reflection surface on the rear side as viewed from the light source is formed in the shape of a parabola,
A light distribution device. A linear light guide that guides light in one direction using total reflection;
A light distribution path that is disposed on the light guide path and distributes light traveling through the light guide path in a predetermined target direction using total reflection, the light distribution path extending in the light guide path and the predetermined target direction. When the surface along both of the directions is a cross section, the cross-sectional shape of the reflective surface on the rear side as viewed from the light source among the reflective surfaces constituting the light distribution path is a shape approximating a parabola, A light distribution path formed in a shape in which the inclination angle of the rear-side reflection surface with respect to the light guide path extension direction increases in multiple stages so as to trace the parabola;
A light distribution device. The focal point of the parabola is located in the light guide on the opening that allows light in the light guide to enter the light distribution path,
The light distribution device according to claim 1 or 2. The focal point of the parabola is located at the midpoint of the opening,
The light distribution device according to claim 3. The inclination angle of the connecting portion of the rear reflective surface with the opening with respect to the light guide path extension direction is less than an angle defined by a critical angle at which refracted light disappears with respect to incident light.
The light distribution device according to claim 3. The area of the opening is determined based on angular dispersion of the light when light is distributed in the predetermined target direction by the light distribution path.
The light distribution device according to claim 5. Area of the opening, the light guiding path in response to the attenuation characteristics of the propagating light, as the distance along the light guiding direction from the light entrance of the light guide path becomes longer, increases,
The light distribution device according to claim 1 or 2. The light guide is
On the substrate, it is arranged extending linearly according to the light irradiation position to the outside,
The light distribution path is
Arranged on the light guide path according to the light irradiation position,
The light distribution device according to claim 1 or 2. The light guide path is formed on the substrate by printing that irradiates the ultraviolet curable resin filled in the cutout portion of the first sheet cut out in accordance with the pattern shape of the light guide path,
The light distribution path has an irradiation angle through the cutout portion of the second sheet having a pattern shape of the light distribution path with respect to the ultraviolet curable resin filled and applied between the first sheet and the second sheet. It is formed on the light guide path by printing that irradiates variable ultraviolet rays and cleans and removes the remaining non-cured resin.
The light distribution device according to claim 8. The light guide path and the light distribution path are:
It is formed using the resin of the same component,
The light distribution apparatus according to claim 9. The light guide is
Provided for each color of light, and each is optically separated from each other,
A light source unit that generates light to be supplied to each of the light guides;
The light distribution device according to claim 1, further comprising: The light source unit is
White light is split to produce a single color of light that is supplied to each of the light guides;
The light distribution apparatus according to claim 11. The light source unit is
A plurality of light emitting elements that emit light of a single color supplied to each of the light guides;
Using the plurality of light emitting elements to generate light of a single color supplied to each of the light guides;
The light distribution apparatus according to claim 11. A light incident part for entering light of a single color generated by the light source part into the corresponding light guide path at an angle allowing total reflection;
The light distribution device according to claim 12 or 13, further comprising: A condensing lens part for condensing the light emitted from the light distribution path by a lens action;
The light distribution device according to claim 1, further comprising: The light guide is
Provided for each color of light, and each is optically separated from each other,
A light source unit that splits white light into RGB colors using a prism and generates light of a single color that is supplied to each of the light guides;
A light incident part that makes the light of each of the separated RGB colors enter the interior of a light guide corresponding to each color of the RBG at an angle that allows total reflection;
The light distribution device according to claim 1, further comprising:   The backlight apparatus which has a light distribution apparatus in any one of Claims 1-16. The backlight device according to claim 17,
A liquid crystal display unit configured by an array of liquid crystal cells for controlling the transmission of light emitted from the backlight device for each pixel, and
The light distribution path distributes the light traveling inside the light guide path in the direction of the corresponding light transmission portion of the liquid crystal cell.
Liquid crystal display device.

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