JP2009265634A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device, capable of emitting light with high color reproducibility with a simple structure to enable display of an image of high quality through a liquid display panel. <P>SOLUTION: The device comprises a light source including a pseudo white LED chip which emits white light by transmitting light emitted from a blue LED by a phosphor layer; a sheet lighting system including a light guide plate having a light incident surface through which light emitted from the light source is incident and a light emitting surface through which the light incident through the light incident surface is emitted; and a liquid crystal panel disposed on a surface through which light of the sheet lighting system is emitted, and including a color filter including at least a red filter having a red color element, a green filter having a green color element, and a blue filter having a blue color element. The color filter includes a wavelength cut filter disposed in an area corresponding to the green filter to remove light having a wavelength of 570-590 nm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device that illuminates a liquid crystal panel with light emitted from a planar illumination device and displays an image.

  As a liquid crystal display device, there is a configuration including a liquid crystal display panel and a backlight unit (that is, a planar illumination device) that irradiates light from the back side of the liquid crystal display panel and illuminates the liquid crystal display panel. This backlight unit basically includes a light source for illumination, a light guide plate that diffuses light emitted from the light source and irradiates the liquid crystal display panel, and optical members such as a prism sheet and a diffusion sheet.

  Currently, a backlight unit used for a liquid crystal display device such as a large-sized liquid crystal television is mainly a so-called direct type, in which an optical member such as a diffusion plate is disposed directly above a light source for illumination without a light guide plate. It is. In this system, a plurality of cold-cathode tubes, which are light sources, are arranged on the back surface of the liquid crystal display panel, and a uniform light quantity distribution and necessary luminance are ensured with the inside as a white reflecting surface.

  However, in the direct type backlight unit, in order to make the light quantity distribution uniform, the thickness in the direction perpendicular to the liquid crystal display panel needs to be a predetermined thickness, for example, about 30 mm. In the future, a thinner backlight unit will be desired. However, it is considered that it is difficult to realize a backlight unit having a thickness of 10 mm or less, for example, with a direct type, which is thinner from the viewpoint of uneven light quantity. .

Therefore, a backlight unit using a light guide plate in which scattering particles for scattering light in a transparent resin are mixed has been proposed (for example, see Patent Document 1).
Patent Document 1 includes a light scattering light guide having at least one light incident region and at least one light extraction surface region, and light source means for performing light incidence from the light incident surface region. The light scattering light source device is characterized in that the light body has a region that tends to decrease in thickness as it moves away from the light incident surface.

In such a planar illumination device, light emitted from a light source and entering the light-scattering light guide from the light incident surface propagates through the interior at a constant rate once or multiple scattering action. Receive. In addition, a substantial part of the light reaching the both surfaces of the light scattering light guide or the surface of the reflector is reflected and returned to the light scattering light guide.
Through such a complex process, a light beam emitted with high efficiency from the light extraction surface is generated with directivity in the obliquely forward direction when viewed from the direction of the light source. That is, the light emitted from the light source is emitted from the light extraction surface of the light scattering light guide.
Thus, it is described that uniform light can be emitted with high emission efficiency by using a light guide plate mixed with scattering particles.

  As the light guide plate, besides the light guide plate having a shape having a tendency to reduce the thickness as the distance from the light incident surface increases, the thickness decreases as the distance from the light incident surface increases. A planar illuminating device having a light guide plate shaped by abutting a light guide plate having a shape having a tendency is described.

Here, as a light source for making light incident on the light guide plate of the planar lighting device, a light emitting diode (hereinafter also referred to as “LED”) can be used in addition to a fluorescent tube such as a cold cathode tube (Patent Document 2). And Patent Document 3).
Since the LED can emit light with high directivity, by using the LED as a light source, the light incident on the light guide plate can be delivered to the back of the light guide plate, and the planar illumination device is enlarged. be able to. Furthermore, the configuration of the power supply can be simplified.

Various methods have been proposed as methods for improving color reproducibility when a planar illumination device is used in a liquid crystal device.
For example, Patent Document 2 includes a first light source that emits blue monochromatic light and a second light source that emits red monochromatic light, and is generated by wavelength conversion from blue light and blue monochromatic light of the first light source. The light emitted from the white light source is arranged between the white light source that emits white light generated by additive color mixing by mixing the green light and the red light of the second light source and the display surface of the liquid crystal display element. A liquid crystal display device having a structure including color correction means by subtractive color mixing is described.

Patent Documents 3 to 6 also describe a method for adjusting a color filter of a liquid crystal display panel.
For example, in Patent Document 3, the wavelength for each 5 nm between the visible light region 380 and 780 nm is λ _n nm, and the spectral transmittance (%) at the wavelength λ _n nm of the red pixel of the color filter is _expressed as T ^R ( λ _n ), where the relative emission intensity obtained by normalizing the emission intensity of the backlight at the wavelength λ _n nm with the total emission intensity is I (λ _n ), these are I (620-680) × T ^R (620-680). ) A color image display device satisfying ≧ 1.1 is described.

  Patent Document 4 includes a plurality of optical shutters that control the amount of transmitted light, a color filter having three colors of red, green, and blue, and a single white light source that combines the light emission characteristics of each of the three colors. A color display device, wherein the peak wavelength of each color of the light source coincides with the peak wavelength of the transmission wavelength region of each color element of the color filter, and the light source has spectral characteristics in a narrower band than the color filter. The color display device is characterized in that the area of the triangle formed on the color coordinates by the transmitted light of the three colors transmitted through is larger than the area of the triangle indicating the transmission characteristics of the color filter.

  Patent Document 5 discloses a color liquid crystal display device using a blue-green-red light-emitting diode as a backlight color light source and using a blue-green-red color filter, wherein the blue peak wavelength of the light-emitting diode is 430 to 480 nm. The green peak wavelength is in the range of 520 nm to 570 nm, the red peak wavelength is in the range of 620 to 660 nm, and the spectral transmittance of the color filter at each of the blue, green, and red peak wavelengths of the light emitting diode is 80. A liquid crystal display device using a color filter, which is characterized by being at least%, is described.

  Patent Document 6 discloses a color filter having red (R), green (G), and blue (B) pixel portions, and transmission on the shorter wavelength side than the peak wavelength of the transmittance of the green (G) pixel portion. The transmittance of both pixel portions at a wavelength where the transmittance and the transmittance on the longer wavelength side than the peak wavelength of the transmittance of the blue (B) pixel portion coincide with each other is 10% or less, and the transmittance of the green (G) pixel portion A liquid crystal display device using a color filter is described in which the maximum value of the rate is 60% or more and the maximum value of the transmittance of the blue (B) pixel portion is 50% or more.

JP 07-36037 A JP 2005-183139 A JP 2006-47975 A Japanese Patent Application Laid-Open No. 07-253577 JP 2003-207770 A JP 2004-85592 A

  Here, an LED is used as a light source and three types of LEDs having red, green, and blue as central wavelengths of light emission are used as a configuration for emitting white light, and red light, green light, and blue emitted from each LED. A method of emitting white light by emitting light and mixing the colors, and a blue light emitted from the LED by providing a phosphor layer on the light emitting surface of the LED that emits light having a wavelength in the blue or ultraviolet region as a central wavelength. And ultraviolet light is converted into white light by a phosphor layer and emitted.

  In the method using three types of LEDs having light emission central wavelengths of red, green, and blue, desired light is emitted from the light emission surface by adjusting the wavelength and emission intensity of the light emitted from each color LED. However, since various characteristics such as temperature characteristics of the three types of LEDs are different, there are problems such as difficulty in control and complicated driving methods. In addition, there is a problem that it is difficult to increase the light use efficiency and reduce the device cost.

On the other hand, a light source having a structure in which a monochromatic LED and a phosphor are combined, in particular, a structure in which a yellow phosphor is applied to a light emitting surface of an LED that emits blue light can be manufactured at low cost.
However, there is a problem that light emitted by combining such a blue LED and a phosphor has a low color temperature, and it is difficult to adjust the color temperature without reducing the light utilization efficiency. Therefore, there is a problem that the color temperature of the light emitted from the light emitting surface of the planar illumination device is low and adjustment is difficult.

On the other hand, Patent Document 2 proposes a planar lighting device that combines a blue LED and a phosphor to form a pseudo-white light source and further arranges a red LED to improve the saturation.
By arranging the red LED in this manner, the color rendering property of red can be improved, but the color reproducibility of the entire lighting device may not be improved. In addition, the color temperature of light emitted from the light source cannot be improved.

Patent Documents 3 to 6 propose a liquid crystal display device that uses a color filter to enhance the color rendering or color reproducibility of emitted light.
Although the color rendering of the light emitted from the liquid crystal display device can be improved by arranging the color filter and transmitting the color filter in this way, the color reproduction of the entire lighting device can be achieved with the color filter configured as described above. Sometimes it is not possible to increase sex. In addition, the color temperature of light emitted from the light source cannot be improved.

  In addition, a thin tandem backlight unit that uses a light guide plate that decreases in thickness as it moves away from the light source can be realized, but the light utilization efficiency depends on the relative dimensions of the cold cathode tube and the reflector. There was a problem that it was inferior to the direct type. In addition, when using a light guide plate having a shape that accommodates a cold cathode tube in a groove formed in the light guide plate, the thickness can be reduced as the distance from the cold cathode tube increases, but when the thickness of the light guide plate is reduced, There is a problem that the luminance directly above the cold cathode tubes arranged in the grooves is increased, and the luminance unevenness of the light exit surface becomes remarkable. In addition, these types of light guide plates are complicated in shape, which increases processing costs, and is used for backlights of liquid crystal televisions having a large size, for example, a screen size of 37 inches or more, particularly 50 inches or more. When the light guide plate is used, there is a problem that the cost becomes high.

In addition, light guide plates that have increased thickness as they move away from the light incident surface have been proposed in order to stabilize production and suppress luminance (light quantity) unevenness using multiple reflections. In addition, since the light incident from the light source passes through to the end portion in the opposite direction as it is, it is necessary to provide a prism or a dot pattern on the lower surface.
In addition, there is a method of disposing a reflecting member at the end opposite to the light incident surface so that the incident light is multiple-reflected and emitted from the light emitting surface, but in order to increase the size, it is necessary to make the light guide plate thicker , It becomes heavy and the cost is high. There is also a problem that the light source is reflected, resulting in uneven brightness.

On the other hand, in the sidelight system using a flat light guide plate, minute scattering particles are dispersed inside in order to efficiently emit incident light from the light exit surface. In such a flat light guide plate, if the scattering fine particles are uniformly dispersed and the screen is enlarged, if the scattering fine particle concentration is 0.30 wt%, the light use efficiency of 83% can be secured, but the solid line in FIG. As shown in the illuminance distribution shown in FIG. 1, there is a problem that the central portion becomes dark and uneven in brightness, that is, uneven in brightness, and is visually recognized.
In order to flatten the luminance unevenness, it is necessary to decrease the concentration of the scattering fine particles to increase the light leaked from the tip, resulting in a decrease in utilization efficiency and a decrease in luminance. For example, if the scattering particle concentration is 0.10 wt% under the same conditions, the luminance unevenness can be greatly reduced as shown by the dotted line in FIG. 35, but the luminance is reduced and the light utilization efficiency is also reduced to 43%. There was a problem.
Furthermore, the brightness distribution on the light exit surface required for large displays such as large liquid crystal televisions is a so-called medium-high distribution, for example, a bell-shaped distribution near the center of the screen compared to the periphery. . However, a flat-shaped light guide plate in which scattered fine particles are dispersed can obtain a flat brightness distribution by reducing the concentration of the scattered fine particles, but there is a problem that a medium-high brightness distribution cannot be realized. It was.

  For thin backlights, it is also considered to use a light guide plate that increases in thickness as it moves away from the light source, as opposed to a tandem light guide plate. However, there is no disclosure about obtaining a light distribution near the center of the screen required for large-screen flat-screen LCD TVs compared to the periphery, so-called medium-high brightness distribution. There was a problem that wasn't done.

  In addition, the large light guide plate greatly expands and contracts due to ambient temperature and humidity, and repeats expansion and contraction of 5 mm or more with a size of about 50 inches. When the light guide plate expands and contracts, the light guide plate and the light source (for example, LED chip) may come into contact with each other, and the light source may fail, the light source may be misaligned, or the light guide plate may be damaged. Such failure of the light source, misalignment, and scratches on the light guide plate are problematic because they cause uneven brightness.

An object of the present invention is to solve the problems based on the above prior art, emit light with a simple configuration and high color reproducibility, and display a high-quality image from a liquid crystal display panel. An object of the present invention is to provide a liquid crystal display device.
Another object of the present invention is in addition to the above-described object, and has a large and thin shape, which can emit light with high light use efficiency and low luminance unevenness, and is required for a large-screen thin liquid crystal television. It is an object to provide a liquid crystal display device that can obtain a light distribution near the center of the screen to be compared with the periphery, that is, a so-called medium-high or bell-shaped brightness distribution, and that has little or no failure. .

  In order to solve the above-described problems, the present invention provides a light guide plate having a light incident surface on which light is incident, a light emitting surface that emits light incident from the light incident surface, and the light incident surface facing the light incident surface. At least one LED unit including at least one pseudo white LED unit having a blue LED that emits blue light and a yellow phosphor layer that is disposed between the blue LED and the light incident surface. A planar illumination device having a light source, and a red filter that is disposed on a light emission surface of the planar illumination device and includes at least a red color element, a green filter that includes a green color element, and a blue filter that includes a blue color element A liquid crystal panel including a color filter composed of: 570 nm or more and 590 n disposed in a region corresponding to the green color filter. There is provided a liquid crystal display device characterized by having a wavelength cut filter for removing light of a wavelength.

Here, it is preferable that the wavelength cut filter removes light having a wavelength of 570 nm or more.
The red filter preferably has a wavelength of 585 nm or more and less than 600 nm at which the transmittance starts to increase sharply.
The green filter preferably has a wavelength with a maximum transmittance of greater than 500 nm and not greater than 515 nm.
Moreover, it is preferable that the blue filter has a wavelength with a maximum transmittance of greater than 440 nm and less than 455 nm.

In order to solve the above problems, the present invention is directed to a light guide plate having a light incident surface on which light is incident, a light emitting surface that emits light incident from the light incident surface, and the light incident surface. At least one LED unit including at least one pseudo white LED unit having a blue LED that emits blue light and a yellow phosphor layer that is disposed between the blue LED and the light incident surface. A planar illumination device having a light source, and a red filter including at least a red color element, a green filter including a green color element, and a blue color element disposed on a light emission surface of the planar illumination device. A liquid crystal panel including a color filter composed of a blue filter. There is provided a liquid crystal display device, characterized in that it.
Here, it is preferable that the green filter has a wavelength with a maximum transmittance of more than 500 nm and less than 515 nm.
Moreover, it is preferable that the blue filter has a wavelength with a maximum transmittance of greater than 440 nm and less than 455 nm.

In order to solve the above problems, the present invention is directed to a light guide plate having a light incident surface on which light is incident, a light emitting surface that emits light incident from the light incident surface, and the light incident surface. At least one LED unit including at least one pseudo white LED unit having a blue LED that emits blue light and a yellow phosphor layer that is disposed between the blue LED and the light incident surface. A planar illumination device having a light source, and a red filter including at least a red color element, a green filter including a green color element, and a blue color element disposed on a light emission surface of the planar illumination device. A liquid crystal panel including a color filter composed of a blue filter, and the green filter has a wavelength with a maximum transmittance of greater than 500 nm and less than or equal to 515 nm. There is provided a liquid crystal display device according to claim Rukoto.
Here, it is preferable that the blue filter has a wavelength with a maximum transmittance of greater than 440 nm and less than 455 nm.

  In order to solve the above problems, the present invention is directed to a light guide plate having a light incident surface on which light is incident, a light emitting surface that emits light incident from the light incident surface, and the light incident surface. At least one LED unit including at least one pseudo white LED unit having a blue LED that emits blue light and a yellow phosphor layer that is disposed between the blue LED and the light incident surface. A planar illumination device having a light source, and a red filter having at least a red color element, a green filter having a green color element, and a blue color element disposed on a light emission surface of the planar illumination device. A liquid crystal panel including a color filter composed of a blue filter, and the blue filter has a wavelength with a maximum transmittance of greater than 440 nm and less than 455 nm. There is provided a liquid crystal display device according to claim Rukoto.

Here, the phosphor layer converts the blue light emitted from the light emitting surface of the blue LED into white light, and emits the blue light emitted from the light emitting surface as blue light. It is preferable to be comprised with the emitted blue light transmissive part.
Moreover, it is preferable that the said blue light transmissive part is formed of the transparent film or opening.

The LED unit further includes at least one blue LED chip that is disposed in the vicinity of the pseudo white LED and emits blue light. The pseudo white LED chip has the phosphor layer of the blue LED. The intensity of the peak in the blue wavelength region of the light, which is arranged on the surface and mixed with the light emitted from the pseudo white LED chip and the light emitted from the blue LED chip, is I _0, and the intensity at a wavelength of 580 nm is I _580. It is preferable that I ₅₈₀ / I ₀ > 0.6 is satisfied.
Moreover, it is preferable that the blue LED chip emits blue light having a wavelength dependency different from that of the blue LED constituting the pseudo white LED chip.
The LED unit preferably has two types of pseudo white LED chips having different emission wavelengths.
The light source includes a plurality of the LED units and a support that supports the plurality of LED units, and the plurality of LED units are arranged in a row on one surface of the support. It is preferable.
In addition, the light guide plate includes a rectangular light exit surface, two light incident surfaces each including two opposing long sides of the light exit surface, and disposed at positions facing each other, and the two light incident surfaces. Two symmetrical inclined surfaces whose distance from the light emitting surface becomes farther toward the center of the light emitting surface, and a curved portion that joins these two inclined surfaces, and scatters light propagating into the inside. Preferably it contains scattering particles.

The light guide plate has a light guide length between the two light incident surfaces of 280 mm or more and 320 mm or less, a particle size of the scattering particles of 4.0 μm or more and 12.0 μm or less, and a concentration of the scattering particles of , 0.1 wt% or more and 0.76 wt% or less, and the particle diameter and concentration of the scattering particles are set such that the particle diameter (μm) of the scattering particles is on the horizontal axis, and the concentration of the scattering particles (wt%). In the graph with the vertical axis, 6 points (4.0, 0.1), (4.0, 0.32), (7.0, 0.14), (7.0, 0.5), Light that is in a region surrounded by (12.0, 0.25) and (12.0, 0.76), and indicates the ratio of the light incident from the two light incident surfaces emitted from the light emitting surface The light output relative to the luminance of light emitted from the vicinity of the light incident surface of the light output surface is 55% or more. Middle-high ratio of brightness distribution of the light emission surface indicating a ratio of brightness of light emitted from the central portion of the surface is 0 percent, preferably not more than 25%.
In the light guide plate, a light guide length between the two light incident surfaces is 480 mm or more and 500 mm or less, and a particle diameter of the scattering particles is 4.0 μm or more and 12.0 μm or less. The concentration is 0.02 wt% or more and 0.22 wt% or less, and the particle diameter and concentration of the scattering particles are set such that the particle diameter (μm) of the scattering particles is a horizontal axis, and the particle concentration of the scattering particles ( In the graph with the vertical axis (wt%), 6 points (4.0, 0.02), (4.0, 0.085), (7.0, 0.03), (7.0, 0.0. 12) The ratio of the light incident from the two light incident surfaces that is in the region surrounded by (12.0, 0.06) and (12.0, 0.22) emitted from the light output surface The luminous efficiency of light emitted from the vicinity of the light incident surface of the light emitting surface is 55% or more. Middle-high ratio of brightness distribution of the light emission surface indicating a ratio of brightness of light emitted from a central portion of the light exit surface with respect to the 0 percent, preferably not more than 25%.
The light guide plate has a light guide length between the two light incident surfaces of 515 mm to 620 mm, a particle size of the scattering particles of 4.0 μm to 12.0 μm, and a concentration of the scattering particles. Is not less than 0.015 wt% and not more than 0.16 wt%, and the particle diameter and concentration of the scattering particles are such that the particle diameter (μm) of the scattering particles is the horizontal axis, and the particle concentration (wt %) On the vertical axis, 6 points (4.0, 0.015), (4.0, 0.065), (7.0, 0.02), (7.0, 0.09) ), (12.0, 0.035) and (12.0, 0.16).

In the light guide plate, a light guide length between the two light incident surfaces is 625 mm or more and 770 mm or less, a particle diameter of the scattering particles is 4.0 μm or more and 12.0 μm or less, and the concentration of the scattering particles is Is 0.01 wt% or more and 0.12 wt% or less, and the particle diameter and concentration of the scattering particles are set such that the particle diameter (μm) of the scattering particles is a horizontal axis, and the particle concentration (wt%) of the scattering particles is ) On the vertical axis, 6 points (4.0, 0.01), (4.0, 0.05), (7.0, 0.01), (7.0, 0.06) , (12.0, 0.02) and (12.0, 0.12) are also preferable.
The light guide plate has a light guide length between the two light incident surfaces of 785 mm or more and 830 mm or less, a particle size of the scattering particles of 4.0 μm or more and 12.0 μm or less, and a concentration of the scattering particles. Is not less than 0.008 wt% and not more than 0.08 wt%, and the particle diameter and concentration of the scattering particles are set such that the particle diameter (μm) of the scattering particles is a horizontal axis, and the particle concentration (wt%) of the scattering particles is ) On the vertical axis, 6 points (4.0, 0.008), (4.0, 0.03), (7.0, 0.009), (7.0, 0.04) , (12.0, 0.02) and (12.0, 0.08).

  The light guide plate has a thickness of the light incident surface that is the thinnest is 0.5 mm or more and 3.0 mm or less, and a thickness of the center of the bent portion that is the thickest is 1.0 mm or more and 6 mm. 0.04 mm or less, the radius of curvature of the curved portion is 1,500 mm or more and 45,000 mm or less, and the taper of the inclined surface with respect to a line parallel to the light emitting surface is 0.1 ° or more and 2.2 °. The following is preferable.

The light guide plate has a scattering cross section of the scattering particles of Φ, a density of the scattering particles of N _p , a correction coefficient of K _C , and a direction orthogonal to the light exit surface from the light incident surface in the light incident direction. thickness up to the position where the maximum length is taken as _{L G,} the inequality _{1.1 ≦ Φ · N p · L} G · K C ≦ 8.2 and 0.005 ≦ _{K C} ≦ 0.1 Satisfaction is also preferred.

According to the present invention, even when a pseudo white LED chip is used as a light source, a planar illumination device capable of emitting light having a high color reproducibility and NTSC ratio and a high color temperature from the light emitting surface is provided. be able to.
According to the present invention, it is a thin shape, has high light utilization efficiency, can emit light with little unevenness in brightness, and a central portion of the screen required for a large-screen thin liquid crystal television is a peripheral portion. Compared to the above, a bright distribution, that is, a so-called medium-high or bell-shaped brightness distribution can be obtained. Further, it is possible to prevent the light source and the light guide plate from being damaged and the positional relationship from being shifted, and it is possible to obtain a liquid crystal display device that is unlikely to break down and that is less likely to cause uneven brightness.

A liquid crystal display device according to the present invention will be described below in detail based on preferred embodiments shown in the accompanying drawings.
In the following description, a two-sided incident type planar illumination device in which light from a light source is incident on two sides of a light guide plate is a representative example, but the present invention is not limited to this. That is.
FIG. 1 is a perspective view showing an outline of a liquid crystal display device of the present invention composed of a planar illumination device and a liquid crystal display panel, and FIG. 2 is a cross-sectional view taken along line II-II of the liquid crystal display device shown in FIG. FIG. 3 is an enlarged front view showing a part of the color filter in an enlarged manner, and FIG. 4 is an enlarged view of the vicinity of the light source part of the planar illumination device (hereinafter also referred to as “backlight unit”) shown in FIG. FIG. 4A is a partially omitted plan view showing the light guide plate of the backlight unit shown in FIG. 2 and the light sources arranged on the two sides thereof, and FIG. 4B is a BB line in FIG. It is sectional drawing.

  As shown in FIG. 1, the liquid crystal display device 10 drives a backlight unit 20, a liquid crystal display panel 12 disposed on the light emission surface (light emission surface) side of the backlight unit 20, and the liquid crystal display panel 12. Drive unit 14. In FIG. 1, a part of the liquid crystal display panel 12 is not shown in order to show the configuration of the backlight unit 20.

The liquid crystal display panel 12 is arranged in a specific direction in advance, and a liquid crystal cell layer in which liquid crystal cells that change the arrangement of molecules by applying an electric field and switch between transmission and non-transmission of light are regularly arranged. (Not shown) and a color filter 80 disposed on the display surface side of the liquid crystal cell layer (the surface on the side from which the light incident on the liquid crystal cell is emitted).
The liquid crystal display panel 12 selectively applies an electric field to each liquid crystal cell in the liquid crystal cell layer to change the molecular arrangement, changes the refractive index generated in the liquid crystal cell, and switches between transmission and non-transmission of light, By selecting light that passes through the color filter 80, characters, figures, images, and the like are displayed on the surface of the liquid crystal display panel 12.

Hereinafter, the color filter 80 of the liquid crystal display panel 12 will be described.
FIG. 3 is an enlarged front view showing a part of the color filter in an enlarged manner.
The color filter 80 includes a red filter 82R that transmits red light component light, a green filter 82G that transmits green light component light, a blue filter 82B that transmits blue light component light, and a cut filter 83. And disposed inside the liquid crystal display panel 12.

As shown in FIG. 3, the red filter 82R, the green filter 82G, and the blue filter 82B constituting the color filter 80 are arranged in order based on a certain rule. More specifically, a red filter 82R, a green filter 82G, and a blue filter 82B are arranged corresponding to one pixel of the liquid crystal display panel 12, respectively. The cut filter 83 is disposed on the surface of the green filter 82G. Further, the above-described liquid crystal cell is arranged corresponding to each filter.
In the present embodiment, the color filter 80 is divided into a checkered pattern, and one red filter 82R, one green filter 82G, and one blue filter 82B are arranged in this order for one divided checkered region. In other words, in this embodiment, one pixel of the liquid crystal display panel is constituted by three cells in which each color is arranged.

Here, the filters of the respective colors are filters having different transmittance characteristics, and are filters having a high spectral transmittance in the wavelength range of the corresponding color and a low transmittance in the other wavelength ranges.
Specifically, the red filter 82R is a film having high transmittance characteristics of light having a wavelength of 600 nm or more, which is a red light component, and low spectral transmittance of light in other wavelength regions.
The green filter 82G is a film having a transmittance characteristic that has a high spectral transmittance of light having a wavelength of 500 nm to 570 nm, which is a green light component, and low spectral transmittance of light in other wavelength regions.
The blue filter 82B is a film having high transmittance characteristics of light having a wavelength of 420 nm or more and 500 nm or less, which is a blue light component, and low transmittance characteristics of light in other wavelength ranges.
In other words, the red filter 82R has a wavelength with a maximum spectral transmittance of 600 nm or more, the green filter 82G has a wavelength with a maximum spectral transmittance of 500 nm or more and 570 nm or less, and the blue filter 82B The wavelength with the maximum transmittance is 420 nm or more and 500 nm or less.

  In the present embodiment, the filters for the respective colors are provided equally, but the present invention is not limited to this, and the ratio may be different for each color. Further, the arrangement order is not particularly limited, and can be an arbitrary order.

The cut filter 83 is arranged over the entire surface of the green filter 82G so that all the light that has passed through the green filter passes through the cut filter 83. In this embodiment, it is affixed to the surface of the green filter 82G. Note that the cut filter 83 is disposed only corresponding to the green filter 82G, and is not disposed at a position where light transmitted through the blue filter 82B and the red filter 82R passes.
The cut filter 83 is a filter that removes light in a wavelength range of 570 nm to 590 nm. That is, the cut filter 83 has a low light transmittance in the wavelength range of 570 nm to 590 nm (at least 30% or less) and a high light transmittance in other wavelength regions (at least 80% or more). It is.
The arrangement position of the cut filter 83 is not particularly limited as long as the cut filter 83 is arranged corresponding to the green filter 82G. The light may pass through the cut filter 83. That is, it is only necessary to obtain an effect of reducing the transmittance of the green filter 82G in the wavelength range of 570 nm to 590 nm. For this reason, the green filter 82G itself may have a cut filter function.

  The color filter 80 is configured as described above, and the light that has passed through the red filter 82R becomes red light, the light that has passed through the green filter 82G, and the light that has passed through the cut filter 83 becomes green light, and the blue filter 82B. The light transmitted through the light becomes blue light and is emitted from the color filter 80. The light transmitted through the green filter 82G is emitted after the light in the wavelength range of 570 nm to 590 nm is removed by the cut filter.

  The drive unit 14 applies a voltage to the transparent electrode in the liquid crystal display panel 12, changes the direction of the liquid crystal molecules in the liquid crystal cell, and controls the transmittance of light transmitted through the liquid crystal display panel 12. That is, as described above, the drive unit 14 controls whether or not light is transmitted through the filters of each color at each position by the liquid crystal cell of the liquid crystal display panel 12. In this way, an image or the like is displayed on the liquid crystal display panel 12 by switching whether to transmit the light that passes through the filter according to the position.

  The backlight unit 20 is an illumination device that irradiates light from the back surface of the liquid crystal display panel 12 to the entire surface of the liquid crystal display panel 12, and has a light emission surface 24 a having substantially the same shape as the image display surface of the liquid crystal display panel 12.

The backlight unit 20 according to the present invention includes two light sources 28, a light guide plate 30, an optical member unit 32, and a reflection plate 34 as shown in FIGS. 1, 2, 4 (A) and 4 (B). The lighting device main body 24 has a lower housing 42, an upper housing 44, a reinforcing member 46, and a supporting member 48.
Further, as shown in FIG. 1, a power storage unit 49 that stores a plurality of power supplies for supplying power to the light source 28 is attached to the back side of the lower housing 42 (see FIG. 2) of the housing 26.
Hereinafter, each component which comprises the backlight unit 20 is demonstrated.

The illumination device body 24 includes a light source 28 that emits light, a light guide plate 30 that emits light emitted from the light source 28 as planar light, and a light that is emitted from the light guide plate 30 by scattering or diffusing the light. It has the optical member unit 32 which makes light nonuniformity, and the reflecting plate 34 which reflects the light leaked from the light guide plate 30 and makes it incident on the light guide plate again.
Here, the optical axis distance between the light guide plate 30 and the light source 28 is a distance between the light emitting surface of the light source 28 and the light incident surfaces (30d, 30e) of the light guide plate 30 as shown in FIG. c. The optical axis vertical distance between the light guide plate 30 and the light source 28 refers to the distance between the respective optical axes in the thickness direction of the light guide plate 30 and the light source 28.

First, the light source 28 will be described.
FIG. 5A is a schematic perspective view showing a schematic configuration of the light source 28 of the backlight unit 20 shown in FIGS. 1 and 2, and FIG. 5B shows an example of the spectral distribution of the pseudo white LED chip. It is a graph. FIG. 5C is a schematic perspective view showing only one pseudo white LED (light emitting diode) chip 54 constituting the light source 28 shown in FIG. 5A in an enlarged manner, as shown in FIG. The light source 28 includes a plurality of LED units 50 and a light source support portion 52.

The LED unit 50 is composed of one pseudo white LED chip.
The pseudo white LED chip 54 is a chip in which a fluorescent material is applied to the surface of a light emitting diode that emits blue light, and emits white light from the light emitting surface 58.
Specifically, the pseudo white LED chip 54 has a characteristic that a fluorescent material applied to the surface of the light emitting diode fluoresces when blue light emitted from the light emitting diode is transmitted. For this reason, the pseudo-white LED chip 54 emits blue light from the light emitting diode, thereby causing the fluorescent material through which the blue light has been transmitted to emit light. White light is generated and emitted by the light emitted when the substance is fluorescent.
Here, the pseudo white LED chip 54 is exemplified by a chip in which a YAG (yttrium, aluminum, garnet) fluorescent material is applied to the surface of a blue LED such as a GaN light emitting diode or an InGaN light emitting diode.
As the blue LED, a GaN light emitting diode, an InGaN light emitting diode, an AlGaN light emitting diode, or the like can be used.
An example of the pseudo white LED chip 54 is a pseudo white LED chip that emits light having a spectral distribution as shown in FIG.
The LED unit 50 is configured as described above.

The light source support portion 52 is a plate-like member that is disposed so as to face the light incident surface (30 d, 30 e) whose one surface is the thinnest side end surface of the light guide plate 30.
The light source support 52 supports the plurality of LED units 50 on a side surface that is a surface facing the light incident surface (30d, 30e) of the light guide plate 30 with a predetermined distance therebetween. Specifically, the plurality of LED units 50 constituting the light source 28 are arranged along the longitudinal direction of the first light incident surface 30d or the second light incident surface 30e of the light guide plate 30 described later, in other words, the light emitting surface 30a. Are arranged in an array parallel to the line where the first light incident surface 30d intersects or parallel to the line where the light emitting surface 30a and the second light incident surface 30e intersect, and are fixed on the light source support 52. ing.
The light source support 52 is formed of a metal having good thermal conductivity such as copper or aluminum, and also has a function as a heat sink that absorbs heat generated from the LED unit 50 and dissipates it to the outside. The light source support portion may be provided with fins that can increase the surface area and enhance the heat dissipation effect, or may be provided with a heat pipe that transfers heat to the heat dissipation member.

Here, as shown in FIG. 5C, the light emitting surface 58 of the pseudo white LED chip 54 of the present embodiment is longer in the direction orthogonal to the arrangement direction than in the arrangement direction of the pseudo white LED chip 54. Has a short rectangular shape, that is, a rectangular shape having a short side in the thickness direction of the light guide plate 30 to be described later (a direction perpendicular to the light emitting surface 30a). In other words, the light emitting surface 58 has a shape in which b> a, where a is the length in the direction perpendicular to the light emitting surface 30a of the light guide plate 30 and b is the length in the arrangement direction. Also, q> b, where q is the arrangement interval between the pseudo white LED chip 54 and the adjacent pseudo white LED chip 54. Thus, the relationship between the length a of the light emitting surface 58 of the pseudo white LED chip 54 in the direction perpendicular to the light emitting surface 30a of the light guide plate 30, the length b in the arrangement direction, and the arrangement interval q of the pseudo white LED chips 54 is as follows. Q>b> a is preferably satisfied.
By making the light emitting surface 58 rectangular, a thin light source can be obtained while maintaining a large light output. By reducing the thickness of the light source, the backlight unit can be reduced in thickness. In addition, the number of LED chips can be reduced.

  Since the pseudo white LED chip 54 can make the light source thinner, it is preferable that the pseudo white LED chip 54 has a rectangular shape in which the thickness direction of the light guide plate 30 is a short side. LED chips having various shapes such as a shape, a polygonal shape, and an elliptical shape can be used.

Further, in this embodiment, since the apparatus can be made thinner and more appropriately mixed in color, the pseudo white LED chip 54 of each LED unit 50 is replaced with the first light incident surface 30d or the second light of the light guide plate 30 described later. Although arranged along the longitudinal direction of the incident surface 30e, the present invention is not limited to this, and the arrangement relationship is not particularly limited, and is orthogonal to the longitudinal direction of the first light incident surface 30d or the second light incident surface 30e. You may arrange in the direction.
In the present embodiment, the LED units 50 are arranged in a single row to form a single layer structure. However, the present invention is not limited to this, and a plurality of LED arrays having a configuration in which a plurality of LED units 50 are arranged on an array support are provided. A multi-layered LED array having a configuration of individual and stacked layers may be used as the light source. Even when LED arrays are stacked in this way, more LED arrays can be stacked by making the pseudo white LED chip 54 of the LED unit 50 rectangular and making the LED array thin. In this manner, a larger amount of light can be output by stacking multiple LED arrays, that is, by increasing the filling rate of the LED array (each LED chip of the LED unit). Moreover, it is preferable that arrangement | positioning space | intervals also satisfy | fill the said formula similarly to the above-mentioned each LED chip of the LED array of the layer adjacent to each LED chip of an LED array. That is, in the LED array, it is preferable that each LED chip of the LED unit and each LED chip of the LED unit of the LED array of the adjacent layer are separated from each other by a predetermined distance.

Next, the light guide plate 30 will be described.
FIG. 6 is a schematic perspective view showing the shape of the light guide plate 30. FIG. 7A is a cross-sectional view illustrating the shape of the light guide plate 30, and FIG. 7B is a partial enlarged cross-sectional view of the light guide plate 30 illustrated in FIG.
As shown in FIGS. 6 and 7, the light guide plate 30 is formed in a substantially rectangular flat light emitting surface 30a and two ends formed substantially perpendicular to the light emitting surface 30a at both ends of the light emitting surface 30a. Two light incident surfaces (first light incident surface 30d and second light incident surface 30e) and opposite to the light emitting surface 30a, that is, on the back side of the light guide plate, the first light incident surface 30d and the second light. Parallel to the incident surface 30e, symmetrical with respect to a bisector α (see FIGS. 1 and 4) that bisects the light emitting surface 30a, and inclined at a predetermined angle with respect to the light emitting surface 30a. Two inclined surfaces (first inclined surface 30b and second inclined surface 30c) and both ends of the light emitting surface 30a where the light incident surface is not formed (perpendicular to the line of intersection between the light emitting surface 30a and the light incident surface) Two side surfaces (first side surface 30) formed substantially perpendicular to the light emitting surface 30a on the two sides. And a the second side surface 30 g). A curved portion 30h having a radius of curvature R is formed at a joint portion between the two inclined surfaces (the first inclined surface 30b and the second inclined surface 30c).

Note that the two light incident surfaces 30d and 30e are located opposite to the opposite long sides of the substantially rectangular light emitting surface 30a, and the two light incident surfaces 30d from the light source 28 disposed facing each other. And 30e propagate in the light guide plate 30 in parallel with the opposing short sides of the substantially rectangular light exit surface 30a.
The first inclined surface 30b and the second inclined surface 30c are axisymmetric with respect to the bisector α, and are inclined symmetrically with respect to the light emitting surface 30a. The curved portion 30h is also curved in line symmetry with respect to the bisector α. The light guide plate 30 has a thickness that increases from the first light incident surface 30d and the second light incident surface 30e toward the center, and a portion corresponding to the bisector α in the center, that is, the center of the curved portion 30h. The portion is thickest (tmax), and the two light incident surfaces (first light incident surface 30d and second light incident surface 30e) at both ends are thinnest (tmin).
That is, the cross-sectional shape of the light guide plate 30 is line symmetric with respect to the central axis passing through the bisector α.

  Here, in the present invention, the light guide length L through which light propagates between the first light incident surface 30d and the second light incident surface 30e is intended for liquid crystal panels having a screen size of 22 inches (22 ″) or more. Therefore, since the liquid crystal panel is 280 mm or more and has a screen size of 65 inches (65 ″) or more, it needs to be 830 mm or less. More specifically, the light guide length L is 280 mm or more and 320 mm or less for a screen size of 22 inches (22 ″), and the light guide length for a screen size of 37 inches (37 ″). L is not less than 480 mm and not more than 500 mm. For screen sizes of 42 inches (42 ″) and 46 inches (46 ″), the light guide length L is not less than 515 mm and not more than 620 mm, and 52 inches (52 ”) And 57 inch (57 ″) screen sizes, the light guide length L is not less than 625 mm and not more than 770 mm, and for 65 inch (65 ″) screen sizes, the light guide length L is 785 mm or more and 830 mm or less.

Further, the minimum thickness tmin of the light incident surfaces 30d and 30e where the light guide plate 30 has the smallest thickness is preferably 0.5 mm or more and 3.0 mm or less.
The reason is that if the minimum thickness is too small, the light incident surfaces 30d and 30e become too small, the light incident from the light source 28 decreases, and light with sufficient luminance cannot be emitted from the light emitting surface 30a. However, if the minimum thickness is too large, the maximum thickness becomes too thick, and the weight is too heavy to be suitable as an optical member such as a liquid crystal display device. It is because it does not satisfy more than%.
The maximum thickness tmax at the center of the curved portion 30h where the light guide plate 30 is thickest is preferably 1.0 mm or more and 6.0 mm or less.
The reason is that if the maximum thickness is too thick, the weight is too heavy to be suitable as an optical member such as a liquid crystal display device, and light penetrates and transmits, so that the light utilization efficiency does not satisfy 55% or more. If the maximum thickness is too thin, the radius of curvature R of the central curved portion 30h is too large to be suitable for molding, and as in the case of a flat plate, at a particle concentration that achieves a medium-high luminance distribution, This is because the light-use efficiency does not satisfy 55% or more, and conversely, a medium-high distribution cannot be realized at a particle concentration at which the light-use efficiency is 55% or more.

Therefore, the taper of the inclined back surfaces 30b and 30c, that is, the taper angle (inclination angle) is preferably 0.1 ° or more and 2.2 ° or less.
The reason is that if the taper is too large, the maximum thickness will be larger than necessary, and the distribution will be too medium and high, and if the taper is too small, the minimum thickness will be small. Similarly to the case where the radius is too large, the curvature radius R (hereinafter also referred to as “center radius R”) of the curved portion 30h is too large to be suitable for molding, and a medium-high distribution is obtained at a particle concentration at which light utilization efficiency is 55% or more. This is because the light utilization efficiency does not satisfy 55% or more at a particle concentration that achieves a medium-high luminance distribution, as in the case of a flat plate.
As a result, the curvature radius R of the curved portion 30h is preferably not less than 1,500 mm and not more than 45,000 mm.
As shown in FIGS. 7A and 7B, when the taper angle of the inclined back surfaces 30b and 30c is θ, L _R = 2R sin θ, and the maximum thickness tmax = tmin + (L / 2) tan θ− [(L _R / 2) tan θ + R cos θ−R] and taper angle θ = tan ⁻¹ [(t max −t min) / (L / 2)].

In the present invention, the shape of the light guide plate 30 is made such that the thickness increases from the first light incident surface 30d and the second light incident surface 30e toward the center (hereinafter referred to as an inverted wedge shape). In this case, the incident light is easily propagated deeper, the in-plane uniformity is improved while maintaining the light use efficiency, and a so-called bell-shaped luminance distribution is obtained. That is, by adopting such a shape, the distribution in which the center becomes dark in the above-described conventional flat light guide plate can be made uniform or medium-high, so-called bell-shaped distribution.
Further, by smoothly joining the central joining portions of the inclined back surfaces 30b and 30c as the curved portion 30h, the band unevenness that can be formed at the central joining portion can be made uniform or medium-high so-called bell-shaped distribution.

Here, an example of changes in light utilization efficiency and in-plane uniformity when the taper angle of the inverted wedge-shaped light guide plate is changed is shown.
In the light guide plate shown in FIG. 7, the light utilization efficiency and in-plane uniformity are simulated when the minimum thickness tmin and the light guide length L are constant, and the maximum thickness tmax is changed and the taper angle θ of the inclined back surface is variously changed. Table 1 shows the results obtained by the above. Here, the in-plane uniformity [%] is a ratio between the minimum luminance and the maximum luminance of the light emitted from the light emitting surface of the light guide plate, and is represented by the minimum luminance / maximum luminance.

Furthermore, in the light guide plate shown in Table 1, FIG. 8 shows the result of obtaining the relationship between the luminance distribution of the light guide plate and the taper angle by simulation. In FIG. 8, the vertical axis is normalized luminance, and the horizontal axis is the distance [mm] from the end of the light guide plate. Here, the normalized luminance is a value normalized by assuming that the average luminance of TP2 which is one of calculation examples is 1.
As shown in Table 1 and FIG. 8, it can be seen that the in-plane uniformity can be improved while making the light use efficiency equal or higher by making the light guide plate into an inverted wedge shape.

Table 2 shows another result obtained by simulating the light utilization efficiency and the medium altitude when the tapered angle θ of the light guide plate is changed for the inverted wedge-shaped light guide plate.
4A and 4B, the taper [°] was changed by changing the maximum thickness [mm] and the minimum thickness [mm] of the 22-inch size light guide plate 30. The light utilization efficiency [%] and the luminance distribution of the light emitted from the light emitting surface 30a are obtained, and the luminance of the light emitted from the periphery of the light emitting surface 30a, that is, from the vicinity of the light incident surfaces 30d and 30e, is determined. The medium altitude [%] of the luminance distribution of the light emitting surface 30a indicating the luminance ratio of the light emitted from the central portion of the light emitting surface 30a was obtained. All parameters other than the taper angle [°] satisfy the preferred limiting range required by the present invention.

  As is clear from Table 2, the light utilization efficiency [%] is higher than 56% and higher than 55% in the range where the taper angle [°] is 0.1 ° or more and 2.2 ° or less. [%] Is also 13% to 22%, and it is understood that the range of more than 0% and 25% or less satisfies the limited range required by the present invention.

  In the light guide plate 30 shown in FIGS. 4A and 4B, the light incident from the first light incident surface 30d and the second light incident surface 30e is scattered fine particles contained in the light guide plate 30 (details will be described later). The light passes through the light guide plate 30 and is reflected directly or after being reflected by the first inclined surface 30b and the second inclined surface 30c, and then emitted from the light emitting surface 30a. At this time, some light may leak from the first inclined surface 30b and the second inclined surface 30c, but the leaked light covers the first inclined surface 30b and the second inclined surface 30c of the light guide plate 30. Then, the light is reflected by a reflecting plate (not shown) and is incident on the light guide plate 30 again.

  The light guide plate 30 is formed by kneading and dispersing minute scattering particles for scattering light in a transparent resin. Examples of the transparent resin material used for the light guide plate 30 include PET (polyethylene terephthalate), PP (polypropylene), PC (polycarbonate), PMMA (polymethyl methacrylate), benzyl methacrylate, MS resin, or COP (cycloolefin polymer). An optically transparent resin such as As the scattering particles kneaded and dispersed in the light guide plate 30, Tospearl, silicone, silica, zirconia, dielectric polymer, or the like can be used. By including such scattering particles in the light guide plate 30, it is possible to emit illumination light that is uniform and has less luminance unevenness from the light exit surface.

Here, the particle size of the scattering fine particles dispersed in the light guide plate 30 used in the backlight unit 20 used in the liquid crystal display device of the present invention needs to be 4.0 μm or more and 12.0 μm or less. The reason is that high scattering efficiency can be obtained, the forward scattering property is large, the wavelength dependency is small, and color unevenness can be selected.
In addition to the wavelength dependency, the following points should be taken into consideration when selecting the optimum particle size of the scattering fine particles to be dispersed in the light guide plate 30 used in the backlight unit 20 used in the liquid crystal display device of the present invention. Is preferred.
First, in the scattered light intensity distribution (angular distribution) by a single particle, it is necessary to satisfy the condition that the light scattered in the forward 0 to 5 ° is 90% or more. This is because the light guide plate 30 used in the backlight unit 20 used in the liquid crystal display device of the present invention having an inverted wedge shape is at least 140 mm from the first light incident surface 30d and the second light incident surface 30e on the side surface of the light guide plate 30. This is because in the case of the above-mentioned distance and single-sided incidence, it is necessary to guide a distance of at least 280 mm or more from the light incident surface. This is because light cannot be guided.

For this reason, when the particle diameter of the scattering fine particles is smaller than 4.0 μm, that is, when the particle diameter is smaller than 4.0 μm, the scattering becomes isotropic, so the above condition cannot be satisfied. When an acrylic resin is selected as the base material and a silicone resin is selected as the particles, the particle size of the silicone resin scattering fine particles is more preferably 4.5 μm or more.
On the other hand, if the particle size of the scattering fine particles is larger than 12.0 μm, that is, if it exceeds 12.0 μm, the forward scattering property of the particles becomes too strong, so that the mean free path in the system increases and the number of scattering decreases. For this reason, luminance unevenness (firefly unevenness) between the light sources (LEDs) appears in the vicinity of the incident end, and thus the upper limit value is limited to 12.0 μm.
The reason is that if the particle concentration is too high, it becomes a phenomenon similar to that of a flat plate, so that a medium-high luminance distribution cannot be realized. If the particle concentration is too low, light penetrates and passes through. This is because the utilization efficiency does not satisfy 55% or more.

Thus, by selecting an optimum particle size (combination of particle refractive index and base material refractive index) included in the limited range of the particle size of the scattering fine particles of the present invention, it is possible to obtain outgoing light with no wavelength unevenness. Can do.
In the above-described example, scattering particles having a single particle size are used. However, the present invention is not limited to this, and a mixture of scattering particles having a plurality of particle sizes may be used.

The concentration of the scattering particles is 0.008 wt% or more and 0.76 wt% or less because the light guide length of the light guide plate 30 used in the backlight unit 20 used in the liquid crystal display device of the present invention is 280 mm to 830 mm. Preferably there is.
Specifically, when the light guide length L is 280 mm ≦ L ≦ 320 mm, it is preferable that the concentration of scattering particles be 0.1 wt% or more and 0.76 wt% or less.
When the light guide length of the light guide plate is L = 280 mm corresponding to a screen size of 22 inches and the particle diameter of the scattering particles is 4.5 μm, the concentration of the scattering particles is 0.1 wt% or more and 0.32 wt%. More preferably, it is more preferably 0.14 wt%. When the particle diameter of the scattering particles is 7.0 μm, the concentration of the scattering particles is more preferably 0.14 wt% or more and 0.5 wt% or less, and most preferably 0.21 wt%. . Furthermore, when the particle diameter of the scattering particles is 12.0 μm, the concentration of the scattering particles is more preferably 0.25 wt% or more and 0.76 wt% or less, and most preferably 0.35 wt%. .

When the light guide length L is 480 mm ≦ L ≦ 500 mm, the concentration of the scattering particles is preferably 0.02 wt% or more and 0.22 wt% or less.
In addition, when the light guide length of the light guide plate is L = 480 mm corresponding to a screen size of 37 inches and the particle diameter of the scattering particles is 4.5 μm, the concentration of the scattering particles is 0.02 wt% or more and 0.085 wt%. The content is more preferably as follows, and most preferably 0.047 wt%. When the particle diameter of the scattering particles is 7.0 μm, the concentration of the scattering particles is more preferably 0.03 wt% or more and 0.12 wt% or less, and most preferably 0.065 wt%. . Furthermore, when the particle diameter of the scattering particles is 12.0 μm, the concentration of the scattering particles is more preferably 0.06 wt% or more and 0.22 wt% or less, and most preferably 0.122 wt%. .

Further, when the light guide length L is 515 mm ≦ L ≦ 620 mm, the concentration of the scattering particles is preferably 0.015 wt% or more and 0.16 wt% or less.
In addition, when the light guide length of the light guide plate is L = 560 mm corresponding to a screen size of 42 inches and the particle diameter of the scattering particles is 4.5 μm, the concentration of the scattering particles is 0.015 wt% or more and 0.065 wt%. More preferably, it is more preferably 0.035 wt%. When the particle diameter of the scattering particles is 7.0 μm, the concentration of the scattering particles is more preferably 0.02 wt% or more and 0.09 wt% or less, and most preferably 0.048 wt%. . Furthermore, when the particle diameter of the scattering particles is 12.0 μm, the concentration of the scattering particles is more preferably 0.04 wt% or more and 0.16 wt% or less, and most preferably 0.09 wt%.

  In addition, when the light guide length of the light guide plate is L = 590 mm corresponding to a screen size of 46 inches and the particle diameter of the scattering particles is 4.5 μm, the concentration of the scattering particles is 0.015 wt% or more and 0.060 wt%. More preferably, it is more preferably 0.031 wt%. When the particle diameter of the scattering particles is 7.0 μm, the concentration of the scattering particles is more preferably 0.02 wt% or more and 0.08 wt% or less, and most preferably 0.043 wt%. . Furthermore, when the particle diameter of the scattering particles is 12.0 μm, the concentration of the scattering particles is more preferably 0.035 wt% or more and 0.15 wt% or less, and most preferably 0.081 wt%.

When the light guide length L is 625 mm ≦ L ≦ 770 mm, the concentration of the scattering particles is preferably 0.01 wt% or more and 0.12 wt% or less.
When the light guide length of the light guide plate is L = 660 mm corresponding to a screen size of 52 inches and the particle diameter of the scattering particles is 4.5 μm, the concentration of the scattering particles is 0.010 wt% or more and 0.050 wt% or less. Is more preferable, and 0.025 wt% is most preferable. When the particle diameter of the scattering particles is 7.0 μm, the concentration of the scattering particles is more preferably 0.015 wt% or more and 0.060 wt% or less, and most preferably 0.034 wt%. Furthermore, when the particle diameter of the scattering particles is 12.0 μm, the concentration of the scattering particles is more preferably 0.030 wt% or more and 0.120 wt% or less, and most preferably 0.064 wt%.

  Furthermore, when the light guide length of the light guide plate is L = 730 mm corresponding to a screen size of 57 inches and the particle diameter of the scattering particles is 4.5 μm, the concentration of the scattering particles is 0.010 wt% or more and 0.040 wt% or less. Is more preferable, and 0.021 wt% is most preferable. When the particle diameter of the scattering particles is 7.0 μm, the concentration of the scattering particles is more preferably 0.010 wt% or more and 0.050 wt% or less, and most preferably 0.028 wt%. . Furthermore, when the particle diameter of the scattering particles is 12.0 μm, the concentration of the scattering particles is preferably 0.020 wt% or more and 0.100 wt% or less, and most preferably 0.053 wt%.

When the light guide length L is 785 mm ≦ L ≦ 830 mm, it is preferable that the concentration of the scattering particles is 0.006 wt% or more and 0.08 wt% or less.
Further, when the light guide length of the light guide plate is L = 830 mm corresponding to a screen size of 65 inches and the particle diameter of the scattering particles is 4.5 μm, the concentration of the scattering particles is 0.008 wt% or more and 0.030 wt% or less. More preferably, it is most preferable to set it as 0.016 wt%. When the particle diameter of the scattering particles is 7.0 μm, the concentration of the scattering particles is more preferably 0.009 wt% or more and 0.040 wt% or less, and most preferably 0.022 wt%. . Furthermore, when the particle diameter of the scattering particles is 12.0 μm, the concentration of the scattering particles is more preferably 0.020 wt% or more and 0.080 wt% or less, and most preferably 0.041 wt%. .

As described above, in the present invention, the particle size and concentration of the scattering particles dispersed in the light guide plate 30 satisfy a predetermined relationship according to the light guide length between the two light incident surfaces 30d and 30e of the light guide plate 30. It turns out that is preferable.
Therefore, in the present invention, when the light guide length of the light guide plate 30 is 280 mm or more and 320 mm or less, as described above, the particle size of the scattering particles is 4.0 μm or more and 12.0 μm or less. The concentration is preferably 0.1 wt% or more and 0.76 wt% or less, and as shown in the graph of FIG. 9, the particle diameter (μm) of the scattering particles is taken as the horizontal axis, and the particle concentration ( wt%) is the vertical axis, the particle size and concentration of the scattering particles are 6 points (4.0, 0.1), (4.0, 0.32), (7.0, 0.14). , (7.0, 0.5), (12.0, 0.25) and (12.0, 0.76).

When the particle size is 480 mm or more and 500 mm or less, as described above, the particle size of the scattering particles is 4.0 μm or more and 12.0 μm or less, and the concentration of the scattering particles is 0.02 wt% or more and 0.22 wt% or less. In addition, as shown in the graph of FIG. 10A, when the horizontal axis is the particle size (μm) of the scattering particles and the vertical axis is the particle concentration (wt%) of the scattering particles, the scattering is The particle size and concentration of the particles are 6 points (4.0, 0.02), (4.0, 0.085), (7.0, 0.03), (7.0, 0.12), It is preferable to be in the region surrounded by (12.0, 0.06) and (12.0, 0.22).
When the light guide length of the light guide plate 30 is 515 mm or more and 620 mm or less, as described above, the particle size of the scattering particles is 4.0 μm or more and 12.0 μm or less, and the concentration of the scattering particles is 0.00. Scattering is 015 wt% or more and 0.16 wt% or less, and the particle diameter (μm) is on the horizontal axis and the particle concentration (wt%) is on the vertical axis as shown in the graph of FIG. The particle size and concentration of the particles are 6 points (4.0, 0.015), (4.0, 0.065), (7.0, 0.02), (7.0, 0.09), It is preferably in the region surrounded by (12.0, 0.035) and (12.0, 0.16).

When the light guide length of the light guide plate 30 is 625 mm or more and 770 mm or less, as described above, the particle size of the scattering particles is 4.0 μm or more and 12.0 μm or less, and the concentration of the scattering particles is 0.00. When the particle size (μm) is on the horizontal axis and the particle concentration (wt%) is on the vertical axis as shown in the graph of FIG. 11A, the scattering particles are 01 wt% or more and 0.12 wt% or less. Particle size and concentration of 6 points (4.0, 0.01), (4.0, 0.05), (7.0, 0.01), (7.0, 0.06), ( 12.0, 0.02) and (12.0, 0.12).
When the light guide length of the light guide plate 30 is 785 mm or more and 830 mm or less, as described above, the particle diameter of the scattering particles is 4.0 μm or more and 12.0 μm or less, and the concentration of the scattering particles is 0.00. Scattering is 008 wt% or more and 0.08 wt% or less, and the particle diameter (μm) is on the horizontal axis and the particle concentration (wt%) is on the vertical axis as shown in the graph of FIG. The particle size and concentration of the particles are 6 points (4.0, 0.008), (4.0, 0.03), (7.0, 0.009), (7.0, 0.04), It is preferable to be in a region surrounded by (12.0, 0.02) and (12.0, 0.08).

  The reason why the particle size and concentration of the scattering particles are preferably within the region surrounded by the six points in the graphs shown in FIGS. 9, 10 </ b> A, 10 </ b> B, 11 </ b> A and 11 </ b> B. Outside this region, if the particle concentration is too high, it will be the same as a flat plate, and a medium-high luminance distribution cannot be realized, and if the particle concentration is too low, light will penetrate and pass through. This is because when the particle size is too small, the light utilization efficiency is improved. However, when the particle size is too large, the light distribution efficiency is improved. This is because the light utilization efficiency is low.

Thus, by selecting the optimum particle concentration included in the limited range of the particle concentration of the scattering fine particles of the present invention, it is possible to emit light with higher light utilization efficiency compared to the case where it is dispersed in a flat light guide plate. it can. In the present invention, light utilization efficiency of at least 55% or more, that is, exceeding 70% can be achieved.
From the above, since an optimum combination of particle diameter and particle concentration can be selected, the light emitted from the LED light source can be emitted uniformly with a mixing length of about 10 mm by selecting these combinations.

The light guide plate 30 used in the backlight unit 20 used in the liquid crystal display device according to the present invention in which the scattering fine particles are dispersed inside has a ratio of the light incident from the two light incident surfaces emitted from the light emitting surface. The light utilization efficiency shown is preferably 55% or more. The reason for this is that if the light utilization efficiency is less than 55%, a light source with a higher output is required to obtain the required luminance. However, if a light source with a higher output is used, the light source becomes hot and power consumption is increased. This is because the warpage and elongation of the light guide plate 30 increase, and the required brightness distribution, that is, the so-called medium-high or bell-shaped brightness distribution cannot be obtained.
Further, the medium to altitude of the luminance distribution of the light emitting surface, which indicates the ratio of the luminance of the light emitted from the central portion of the light emitting surface to the luminance of the light emitted from the vicinity of the light incident surface of the light emitting surface, is greater than 0%. It is preferable that it is 25% or less. The reason for this is that the vicinity of the center of the screen required for a large-screen thin LCD TV is brighter than the periphery, that is, a so-called medium-high or bell-shaped brightness distribution.
Such a light guide plate 30 can be manufactured using an extrusion molding method or an injection molding method.

Here, the light guide plate 30 includes a first light incident surface 30d, a second light incident surface 30e, a light emitting surface 30a, which are light incident surfaces, a first inclined surface 30b, and a second inclined surface 30c, which are light reflecting surfaces. It is preferable that the surface roughness Ra of at least one of the surfaces is smaller than 380 nm, that is, Ra <380 nm.
By making the surface roughness Ra of the first light incident surface 30d and the second light incident surface 30e to be light incident surfaces smaller than 380 nm, diffuse reflection on the surface of the light guide plate can be ignored, that is, the surface of the light guide plate Diffuse reflection can be prevented, and the incident efficiency can be improved.
Further, by making the surface roughness Ra of the light exit surface 30a smaller than 380 nm, the diffuse reflection transmission on the light guide plate surface can be ignored, that is, the diffuse reflection transmission on the light guide plate surface can be prevented, Light can be transmitted to the back by total reflection.
Furthermore, by making the surface roughness Ra of the first inclined surface 30b and the second inclined surface 30c to be light reflecting surfaces smaller than 380 nm, diffuse reflection can be ignored, that is, diffuse reflection on the light reflecting surface is reduced. It is possible to prevent the total reflection component from being transmitted further.

The light guide plate used in the backlight unit used in the liquid crystal display device of the present invention is basically configured as described above, but can be designed as follows.
FIG. 12 is a flowchart showing an example of a method for designing a light guide plate used in a backlight unit used in the liquid crystal display device of the present invention.
First, as shown in FIG. 12, in step S10, the screen size is reduced from the screen size of the liquid crystal display device to which the backlight unit using the light guide plate used in the backlight unit used in the liquid crystal display device of the present invention is applied. The light guide length is determined by adding about 10 mm as the mixing zone length to the side length.
Next, in step S12, the maximum thickness tmax of the light guide plate is determined from the screen size.
In step S14, the base material resin used for the light guide plate and the particle conditions of the scattering fine particles to be added are determined.

  Subsequently, in step S16, the particle concentration at which the light use efficiency E [%] is 55% or more is determined in the flat-plate-shaped scattered fine particle dispersion light guide plate (scattering light guide plate) having the determined light guide length. Here, E = Iout / Iin × 100 [%], and Iout and Iin represent incident and outgoing light beams [lm], respectively. The particle concentration is determined by simulation. If there is a difference between the actual measurement value of the light utilization efficiency E and the simulation value, it is necessary to determine the design value of the particle concentration in consideration of the difference. There is. If there is this difference, it is preferable to obtain in advance the difference between the actual measured value and the simulation value of the light utilization efficiency E.

  Next, in step S18, the design value of the particle concentration is fixed, and the taper angle θ or the maximum thickness tmax of the inclined back surface shape (reverse wedge shape) of the light guide plate used in the backlight unit used in the liquid crystal display device of the present invention is set. The brightness distribution of the light exit surface of the light guide plate is obtained and the taper angle θ is determined by grasping whether or not the medium altitude is within a predetermined range. At this time, the radius of curvature R of the central curved portion is determined according to the light guide length and combined with the taper. Here, the intermediate altitude degree D is represented by 0 <D ≦ 25 and D = [(Lcen−Ledg) / Lcen] × 100 [%]. Here, the medium altitude degree D means the medium altitude degree (the degree at which the central portion becomes higher), and Lcen and Ledg represent the luminance at the central portion and the luminance at the screen end side (near the incident portion), respectively. . The taper angle θ is determined by simulation. If there is a difference between the measured value of the particle concentration and the simulation value, the luminance distribution is grasped in consideration of the difference, and the intermediate altitude D It is necessary to determine the taper angle θ. When there is this difference, it is preferable to obtain the difference between the actually measured value of the particle concentration and the simulation value in advance.

Subsequently, in step S20, the incident portion thickness (minimum thickness) tmin is determined from the relationship between the maximum thickness tmax of the light guide plate and the taper (taper angle θ) and the radius of curvature R of the central curved portion. An LED chip having a light emitting part with a thickness less than the incident part thickness tmin is selected.
Thus, a light guide plate used for the backlight unit used in the liquid crystal display device of the present invention can be designed.
The relationship between the particle concentration [wt%], the light utilization efficiency [%], and the intermediate altitude [%] in the case of a light guide plate having a screen size of 37 inches, a maximum thickness of 3.5 mm, and a light guide length of 480 mm As shown in FIG.
As is clear from the figure, in the range of the particle concentration from 0.05 wt% to 0.2 wt%, the light utilization efficiency exceeds 70%, but the particle concentration ranges from 0.05 wt% to 0.07 wt%, and It can be seen that in the range of 0.19 wt% to 0.2 wt%, the intermediate altitude is minus, that is, the luminance distribution is low in the central portion. For example, it is understood that if a medium to high degree of 10% or more is required, the particle concentration needs to be designed in the range of 0.08 wt% to 0.16 wt%.

When the screen sizes designed in this way are 37 inches, 42 inches, 46 inches, 52 inches, 57 inches, and 65 inches, the light guide plate has a light guide length [mm], a maximum thickness [mm], and a particle concentration [wt%]. ], Taper [°], radius of curvature R [mm] of the central curved portion, light utilization efficiency [%] and intermediate altitude [%] are shown in Table 3.

In any case, the light guide plate satisfies the preferable limitation range of the present invention, so that even a large screen has a thin shape, high light utilization efficiency, and emits light with less unevenness in luminance. In addition, a bright distribution in the vicinity of the center of the screen, which is required for a large-screen thin liquid crystal television, compared to the peripheral portion, that is, a so-called medium-high or bell-shaped brightness distribution can be obtained.
The light guide plate used in the backlight unit used in the liquid crystal display device of the present invention is basically configured as described above.

Next, the optical member unit 32 will be described.
The optical member unit 32 converts the illumination light emitted from the light exit surface 30a of the light guide plate 30 into light with no uneven brightness, and emits illumination light with more uniform brightness from the light exit surface 24a of the illumination device body 24. As shown in FIG. 2, a diffusion sheet 32a that diffuses illumination light emitted from the light exit surface 30a of the light guide plate 30 to reduce luminance unevenness, and a tangent line between the light entrance surface and the light exit surface It has a prism sheet 32b on which parallel microprism arrays are formed, and a diffusion sheet 32c that diffuses illumination light emitted from the prism sheet 32b to reduce luminance unevenness.

  As the diffusion sheets 32a and 32c and the prism sheet 32b, those disclosed in [0028] to [0033] of Japanese Patent Application Laid-Open No. 2005-23497 related to the applicant's application can be applied.

In the present embodiment, the optical member unit is constituted by the two diffusion sheets 32a and 32c and the prism sheet 32b disposed between the two diffusion sheets. However, the arrangement order and arrangement of the prism sheets and the diffusion sheets are not limited. The number is not particularly limited, and is also not particularly limited as a prism sheet or a diffusion sheet, as long as the luminance unevenness of the illumination light emitted from the light emitting surface 30a of the light guide plate 30 can be further reduced, Various optical members can be used.
For example, as the optical member, in addition to or in place of the above-described diffusion sheet and prism sheet, a transmittance adjusting member in which a large number of transmittance adjusting bodies made of a diffusive reflector are arranged in accordance with luminance unevenness can also be used.

Next, the reflecting plate 34 of the lighting device main body will be described.
The reflection plate 34 is provided to reflect light leaking from the first inclined surface 30b and the second inclined surface 30c of the light guide plate 30 and to make it incident on the light guide plate 30 again, thereby improving the light utilization efficiency. be able to. The reflection plate 34 has a shape corresponding to the first inclined surface 30b and the second inclined surface 30c of the light guide plate 30, and is formed so as to cover the first inclined surface 30b and the second inclined surface 30c. In the present embodiment, as shown in FIG. 2, the first inclined surface 30b and the second inclined surface 30c of the light guide plate 30 are formed in a triangular cross section, and the reflecting plate 34 is also formed in a shape that complements this. ing.

  The reflecting plate 34 may be formed of any material as long as it can reflect light leaking from the inclined surface of the light guide plate 30. For example, the reflecting plate 34 is stretched after kneading a filler in PET, PP (polypropylene), or the like. Resin sheet with increased reflectivity by forming voids, a sheet with a mirror surface formed by vapor deposition of aluminum on the surface of a transparent or white resin sheet, a resin sheet carrying a metal foil or metal foil such as aluminum, or sufficient on the surface It can be formed of a thin metal plate having excellent reflectivity.

The upper guide reflection plate 36 is disposed between the light guide plate 30 and the diffusion sheet 32a, that is, on the light output surface 30a side of the light guide plate 30, and the end portions of the light output surface 30a of the light source plate 30 and the light guide plate 30 (first light incident). The end portion on the surface 30d side and the end portion on the second light incident surface 30e side) are disposed so as to cover each other. In other words, the upper guide reflection plate 36 is disposed so as to cover from a part of the light emitting surface 30a of the light guide plate 30 to a part of the light source support portion 52 of the light source 28 in a direction parallel to the optical axis direction. . That is, the two upper guide reflectors 36 are disposed at both ends of the light guide plate 30, respectively.
Thus, by arranging the upper guide reflection plate 36, it is possible to prevent the light emitted from the light source 28 from entering the light guide plate 30 and leaking to the light emitting surface 30 side.
Thereby, the light emitted from each LED chip of the LED unit 50 of the light source 28 can be efficiently incident on the first light incident surface 30d and the second light incident surface 30e of the light guide plate 30, and the light utilization efficiency is improved. Can be made.

The lower guide reflection plate 38 is disposed on the opposite side of the light guide plate 30 from the light emitting surface 30a side, that is, on the first inclined surface 30b and the second inclined surface 30c so as to cover a part of the light source 28. . The end of the lower guide reflector 38 on the center side of the light guide plate is connected to the reflector 34.
By providing the lower guide reflection plate 38, the light emitted from the light source 28 can be prevented from leaking to the first inclined surface 30b and the second inclined surface 30c side of the light guide plate 30 without entering the light guide plate 30. .
Thereby, the light emitted from each LED chip of the LED unit 50 of the light source 28 can be efficiently incident on the first light incident surface 30d and the second light incident surface 30e of the light guide plate 30, and the light utilization efficiency is improved. Can be made.
Here, as the upper guide reflector 36 and the lower guide reflector 38, various materials used for the reflector 34 described above can be used.
In the present embodiment, the reflecting plate 34 and the lower guiding reflecting plate 38 are connected. However, the present invention is not limited to this, and each may be a separate member.

Here, the upper guide reflector 36 and the lower guide reflector 38 reflect the light emitted from the light source 28 toward the first light incident surface 30d or the second light incident surface 30e, and the light emitted from the light source 28 is reflected. The shape and width are not particularly limited as long as the light can be incident on the first light incident surface 30d and the second light incident surface 30e and the light incident on the light guide plate 30 can be guided to the center side of the light guide plate 30.
In the present embodiment, the upper guide reflector 36 is disposed between the light guide plate 30 and the diffusion sheet 32a. However, the position of the upper guide reflector 36 is not limited to this, and constitutes the optical member unit 32. You may arrange | position between sheet-like members, and may arrange | position between the optical member unit 32 and the upper housing | casing 44. FIG.

Next, the housing 26 will be described.
As shown in FIG. 2, the housing 26 houses and supports the lighting device main body 24, and is sandwiched between the light emitting surface 24a side and the first inclined surface 30b and second inclined surface 30c side of the light guide plate 30. And a lower casing 42, an upper casing 44, a reinforcing member 46, and a supporting member 48.

  The lower housing 42 has a shape having an open top surface and a bottom surface portion and side surfaces provided on four sides of the bottom surface portion and perpendicular to the bottom surface portion. That is, it is a substantially rectangular parallelepiped box shape with one surface open. As shown in FIG. 2, the lower housing 42 supports the illuminating device main body 24 housed from above with a bottom surface portion and a side surface portion, and also a surface other than the light emitting surface 24 a of the illuminating device main body 24, that is, the illuminating device. The main body 24 covers a surface (back surface) and a side surface opposite to the light emitting surface 24a.

The upper housing 44 has a rectangular parallelepiped box shape in which a rectangular opening smaller than the rectangular light emitting surface 24a of the lighting device body 24 serving as an opening is formed on the upper surface, and the lower surface is opened.
As shown in FIG. 2, the upper housing 44 includes the lighting device main body 24 and the lower housing 42 in which the lighting device main body 24 and the lower housing 42 are housed from above the lighting device main body 24 and the lower housing 42. The side portion is also placed so as to cover the side portion.

The reinforcing member 46 has a concave (U-shaped) shape whose cross-sectional shape is always the same. That is, it is a rod-like member having a U-shaped cross section perpendicular to the extending direction.
As shown in FIG. 2, the reinforcing member 46 is inserted between the side surface of the lower housing 42 and the side surface of the upper housing 44, and the outer surface of one of the U-shaped parallel portions is the lower housing 42. It is connected to the side surface portion, and the outer side surface of the other parallel portion is connected to the side surface of the upper housing 44.
Here, as a method for joining the lower housing 42 and the reinforcing member 46, and a method for joining the reinforcing member 46 and the upper housing 44, various known methods such as a method using a bolt and a nut, a method using an adhesive, and the like. Can be used.

Thus, by arranging the reinforcing member 46 between the lower housing 42 and the upper housing 44, the rigidity of the housing 26 can be increased, and the light guide plate can be prevented from warping. Thereby, for example, light can be emitted efficiently with little or no luminance unevenness, but even when a light guide plate that is likely to warp is used, the warp can be corrected more reliably, or the light guide plate can be warped. It is possible to more reliably prevent the occurrence of light and to emit light having no or uneven brightness or the like from the light exit surface.
In addition, various materials, such as a metal and resin, can be used for the upper housing | casing of a housing | casing, a lower housing | casing, and a reinforcement member. In addition, as a material, it is preferable to use a lightweight and high-strength material.
In this embodiment, the reinforcing member is a separate member, but it may be formed integrally with the upper housing or the lower housing. Moreover, it is good also as a structure which does not provide a reinforcement member.

The support member 48 has a shape with the same cross-sectional shape perpendicular to the extending direction. That is, it is a rod-like member having the same cross-sectional shape perpendicular to the extending direction.
As shown in FIG. 2, the support member 48 is between the reflection plate 34 and the lower housing 42, more specifically, the end of the first inclined surface 30 b of the light guide plate 30 on the first light incident surface 30 d side. The second inclined surface 30c is disposed between the reflecting plate 34 and the lower housing 42 at a position corresponding to the end on the second light incident surface 30e side, and the light guide plate 30 and the reflecting plate 34 are arranged in the lower housing 42. Secure and support.
The light guide plate 30 and the reflection plate 34 can be brought into close contact with each other by supporting the reflection plate 34 with the support member 48. Further, the light guide plate 30 and the reflection plate 34 can be fixed at predetermined positions of the lower housing 42.

In this embodiment, the support member is provided as an independent member. However, the present invention is not limited to this, and the support member may be formed integrally with the lower housing 42 or the reflection plate 34. In other words, a protrusion may be formed on a part of the lower casing 42 and used as a support member, or a protrusion may be formed on a part of the reflector and the protrusion may be used as a support member. .
Further, the arrangement position is not particularly limited, and it can be arranged at an arbitrary position between the reflector and the lower housing, but in order to stably hold the light guide plate, In the present embodiment, it is preferable to dispose near the first light incident surface 30d and near the second light incident surface 30e.

Further, the shape of the support member 48 is not particularly limited, and can be various shapes, and can be made of various materials. For example, a plurality of support members may be provided and arranged at predetermined intervals.
In addition, the support member has a shape that fills the entire space formed by the reflector and the lower housing, that is, the surface on the reflector side is shaped along the reflector, and the surface on the lower housing side is the lower housing. It is good also as a shape along. As described above, when the entire surface of the reflection plate is supported by the support member, it is possible to reliably prevent the light guide plate and the reflection plate from separating, and to prevent uneven brightness from being generated by the light reflected from the reflection plate. be able to.

The backlight unit 20 is basically configured as described above.
The backlight unit 20 emits light from the LED units 50 of the light source 28 disposed at both ends of the light guide plate 30.
The light emitted from the LED unit 50 is incident on the light incident surfaces (the first light incident surface 30d and the second light incident surface 30e) of the light guide plate 30. Light incident from each surface passes through the light guide plate 30 while being scattered by the scatterers included in the light guide plate 30, and directly or after being reflected by the first inclined surface 30b and the second inclined surface 30c. The light exits from the light exit surface 30a. At this time, part of the light leaking from the first inclined surface 30 b and the second inclined surface 30 c is reflected by the reflecting plate 34 and enters the light guide plate 30 again.
In this way, the light emitted from the light emitting surface 30 a of the light guide plate 30 passes through the optical member 32 and is emitted from the light emitting surface 24 a of the illuminating device body 24 to illuminate the liquid crystal display panel 12.
The liquid crystal display panel 12 displays characters, figures, images, and the like on the surface of the liquid crystal display panel 12 by controlling the light transmittance according to the position by the drive unit 14.

  According to the present invention, the cut filter 83 is provided at a position corresponding to the green filter 82G of the color filter 80 of the liquid crystal panel, and the light transmitted through the green filter 82G (that is, light emitted from the region corresponding to the green filter 82G). By removing light in the wavelength range of 570 nm to 590 nm, the color reproducibility as a liquid crystal display device is high even when a pseudo white LED chip is used as the light source, and in particular, the color reproducibility in the green region is increased. The NTSC (National Television System Committee) ratio can be increased. Thereby, an image with high color reproducibility can be displayed on the display surface of the liquid crystal display device, that is, the liquid crystal display panel. A high-quality liquid crystal display device can be provided.

  Moreover, in the said embodiment, although 570 nm or more and 590 nm or less were removed with the cut filter, it is preferable that a cut filter removes the light of all the wavelength ranges 570 nm or more. In this way, by removing all light in the wavelength range of 570 nm or more from the light transmitted through the green filter with the cut filter, even when the pseudo white LED chip is used as the light source, the color reproducibility can be more reliably achieved. In particular, the color reproducibility of the green region can be increased, and the NTSC ratio can be increased.

Here, in the above embodiment, the cut filter 83 is disposed as a color filter at a position corresponding to the green filter 82G. However, the present invention is not limited to this, and the cut filter 83 is disposed at a position corresponding to the green filter 82G. Instead of or in addition, it is also preferable to make the color filter as follows.
For example, the transmission spectrum (filter transmittance distribution) of the red filter 82R of the color filter 80 may be moved to the longer wavelength (wavelength increasing direction) side by a wavelength of 5 nm or more and less than 20 nm. More specifically, it is preferable to move the wavelength at which the transmittance of the red filter 82R starts to increase sharply to the long wavelength side by 5 nm or more and less than 20 nm. Note that steeply rising means that the transmittance changes by 20% or more at 5 nm.
Here, since the transmittance of the red filter usually starts to sharply increase at 580 nm, the red filter of the present invention may be a filter in which the transmittance starts to increase sharply in the wavelength range of 585 nm to less than 600 nm.
In this way, even when the pseudo white LED chip is used as the light source, the liquid crystal display device can be obtained by moving the transmission spectrum (filter transmittance distribution) of the red filter 82R of the color filter 80 to the long wavelength side of 5 nm or more and less than 20 nm. As a result, the color reproducibility can be increased and the NTSC ratio can be increased. In this case, in particular, the color reproducibility of the red region can be increased.

Further, the transmission spectrum (filter transmittance distribution) of the green filter 82G may be moved to the short wavelength (the direction in which the wavelength is shortened) by the wavelength of 5 nm or more and less than 20 nm. More specifically, it is preferable to move the wavelength at which the transmittance of the green filter 82G is maximized to the short wavelength side by not less than 5 nm and less than 20 nm.
Here, since the green filter 82G normally uses a filter having the maximum transmittance at 520 nm, the green filter 82G of the present invention may be a filter having the maximum transmittance in a wavelength region of 500 nm to 515 nm or less. .
In this way, even when the pseudo white LED chip is used as the light source, the liquid crystal display device can be obtained by moving the transmission spectrum (filter transmittance distribution) of the green filter 82G of the color filter 80 to the short wavelength side from 5 nm to less than 20 nm. As a result, the NTSC ratio can be increased. In this case, in particular, the color reproducibility of the green region can be improved.

Alternatively, the transmission spectrum (filter transmittance distribution) of the blue filter 82B may be moved to the short wavelength (the direction in which the wavelength is shortened) by the wavelength of 5 nm or more and less than 20 nm. More specifically, it is preferable to move the wavelength at which the transmittance of the blue filter 82B is maximized to the short wavelength side by not less than 5 nm and less than 20 nm.
Here, since the blue filter 82B normally uses a filter having the maximum transmittance at 460 nm, the blue filter 82B of the present invention may be a filter having the maximum transmittance in a wavelength region greater than 440 nm and less than 455 nm. .
In this way, even when the pseudo white LED chip is used as the light source, the liquid crystal display device can be obtained by moving the transmission spectrum (filter transmittance distribution) of the blue filter 82B of the color filter 80 to the short wavelength side of 5 nm or more and less than 20 nm. As a result, the NTSC ratio can be increased. In this case, in particular, the color reproducibility of the blue region can be increased.

As described above, according to the present invention, the cut filter 83 removes light in the wavelength region of 570 nm or more and 590 nm or less from the region corresponding to the green filter 82G, or the transmission spectrum of the red filter 82R (filter The transmittance distribution of the green filter 82G is moved to the longer wavelength (wavelength increasing direction) side by the wavelength of 5 nm or more and less than 20 nm, or the transmission spectrum of the green filter 82G (filter transmittance distribution) is a wavelength of 5 nm or more and less than 20 nm. Or move to the short wavelength (the direction in which the wavelength is shortened) by the amount, or the blue spectrum 82B has a short wavelength (the direction in which the wavelength is shortened) by a wavelength of 5 nm or more and less than 20 nm. The color reproducibility as a liquid crystal display device can be achieved even when a pseudo white LED chip is used as the light source. Ku, it is possible to increase the NTSC ratio.
Preferably, by combining two or more of the above four characteristics, more preferably by combining all four characteristics, the color reproducibility as a liquid crystal display device can be further improved and the NTSC ratio can be increased. . For example, a cut filter 83 is provided to remove light in the wavelength range of 570 nm to 590 nm from the light emitted from the region corresponding to the green filter 82G, and the transmission spectrum (filter transmittance distribution) of the red filter 82R is further removed. The color reproducibility of the green region and the red region can be increased by moving the wavelength by 5 nm or more and less than 20 nm toward the longer wavelength (the direction in which the wavelength becomes longer), and the NTSC ratio can be further increased. it can. Alternatively, the transmission spectrum (filter transmittance distribution) of the red filter 82R is moved to the longer wavelength (the direction in which the wavelength becomes longer) by the wavelength of 5 nm or more and less than 20 nm, and the transmission spectrum of the green filter 82G (filter transmittance). (Distribution) is shifted to the short wavelength (the direction in which the wavelength is shortened) by the wavelength of 5 nm or more and less than 20 nm, and the transmission spectrum (filter transmittance distribution) of the blue filter 82B is shifted by the wavelength of 5 nm or more and less than 20 nm. By moving to the short wavelength (the direction in which the wavelength becomes shorter), the color reproducibility of the red region, the green region, and the blue region can be increased, and the NTSC ratio can be further increased.

Hereinafter, the liquid crystal display device of the present invention will be described in more detail using specific examples.
Here, FIG. 14 is a graph showing the spectral distribution of the pseudo white LED chip used for the measurement, and FIGS. 15 to 18 are graphs showing the transmittance distributions of the color filters used for the main measurement.
First, for comparison, as a comparative example 01, a liquid crystal display device using a pseudo white LED chip A shown in FIG. 14 as a pseudo white LED and using a general color filter was measured.
Note that the general color filter used in this measurement is a green CF indicated by a broken line (displayed as Comparative Example 01) in FIG. 15, a red CF indicated by a one-dot chain line in FIG. 15, and a two-dot chain line in FIG. The blue CF shown in Example 03).

  In Example 01, as the color filter in Comparative Example 01, a cut filter 83 that removes light in the wavelength range of 570 nm to 590 nm is disposed in a region corresponding to the green filter 82G, and as shown by a solid line in FIG. Measurement was performed on a liquid crystal display device in which the transmittance of 570 nm to 590 nm of the green filter 82G was lower than that of Comparative Example 01 (substantially 0). That is, Example 01 has the same configuration as that of Comparative Example 01 except that the cut filter 83 is provided and the configuration of the green filter 82G is changed. Further, in FIG. 15, the transmittance of the green filter 82G of Example 01 is a result of measuring the light after passing through the green filter and the cut filter.

  Further, in Example 02, as shown by a solid line in FIG. 16, as a color filter, a red color obtained by moving the spectral distribution by 10 nm toward the long wavelength side (solid line from the alternate long and short dash line) with respect to the red filter 82R used in Comparative Example 01. A liquid crystal display device having the same configuration as that of Comparative Example 01 was used except that a filter was used.

  Further, in Example 03, as a color filter in Comparative Example 01, a cut filter that removes light in a wavelength region of 570 nm to 590 nm is disposed in a region corresponding to the green filter 82G, and a red filter 82R is used as a comparative example. Measurement was performed on a liquid crystal display device using a red filter in which the spectral distribution was shifted 10 nm to the long wavelength side with respect to the red filter 82R used in 01. That is, in Example 03, the comparison was performed except that the green filter 82G and cut filter of Example 01 shown by a solid line in FIG. 15 and the red filter 82R of Example 02 shown by a solid line in FIG. 16 were used as color filters. The configuration was the same as in Example 01.

Further, in Example 04, the pseudo white LED chip B shown in FIG. 14 is used as the pseudo white LED, and the spectral distribution with respect to the green filter 82G of Comparative Example 01 is shown as a solid line in FIG. 17 as the green filter. Was measured for a liquid crystal display device having the same configuration as that of Comparative Example 01 except that a green filter was used which was moved 10 nm toward the short wavelength side (from the broken line to the solid line).
Comparative Example 02 had the same configuration as Comparative Example 01 except that the pseudo white LED was changed from pseudo white LED chip A to pseudo white LED chip B. That is, Example 04 and Comparative Example 02 have the same configuration except that the configuration of the green filter (spectral transmission characteristics) is different.

Further, in Example 05 and Example 06, as a pseudo white LED, a pseudo white LED chip C (spectrum distribution not shown) is used, and as a blue filter, as shown by a solid line and a dotted line in FIG. Blue filter 82B (indicated by a two-dot chain line in FIG. 18, indicated as Comparative Example 03) by moving the spectral distribution to the short wavelength side by 5 nm (Example 05) and 10 nm (Example 06), respectively. Measurements were performed on a liquid crystal display device having the same configuration as that of Comparative Example 01 except that it was used.
Comparative Example 03 had the same configuration as Comparative Example 01 except that the pseudo white LED was changed from pseudo white LED chip A to pseudo white LED chip C. That is, Example 05, Example 06, and Comparative Example 03 have the same configuration except that the configuration (spectral transmission characteristics) of the blue filter is different.

Here, in these measurements, the chromaticity (u ′, v ′ coordinates) of light emitted from the liquid crystal display device and the NTSC ratio were measured.
The measurement results are shown in Tables 4 and 5 below.
FIG. 19 shows the three primary color points of the light measurement results emitted from the liquid crystal display devices of Example 01, Example 02, Example 03, and Comparative Example 01, and the chromaticity in the CIEu′v ′ color system. FIG. 20 shows the three primary color points of the light measurement results emitted from the liquid crystal display devices of Example 05, Example 06, and Comparative Example 03 in a chromaticity diagram in the CIEu′v ′ color system. Show.

As shown in Table 4, Table 5, FIG. 19 and FIG. 20, the color filter is configured to remove light in a wavelength range of 570 nm to 590 nm of light emitted from a region corresponding to the green filter 82 </ b> G by the cut filter 83. Or the transmission spectrum (filter transmittance distribution) of the red filter 82R is moved to the longer wavelength (the direction in which the wavelength increases) by the wavelength of 10 nm, or the transmission spectrum of the green filter 82G (filter transmittance). (Distribution) is shifted to the short wavelength (wavelength decreasing direction) side by the wavelength of 10 nm, or the transmission spectrum (filter transmittance distribution) of the blue filter 82B is shifted to the short wavelength (wavelength) by the wavelength of 5 nm or 10 nm. By moving to the direction of shortening (NTS), NTS is more than the case of using the color filter normally used as the color filter. It can be seen that it is possible to increase the ratio.
The cut filter 83 removes light having a wavelength range of 570 nm to 590 nm from the region corresponding to the green filter 82G, and the red filter 82R has a transmission spectrum (filter transmittance distribution) of 10 nm. It can be seen that the NTSC ratio can be further increased by moving to the longer wavelength (the direction in which the wavelength becomes longer) by the wavelength.
From the above, the effects of the present invention are clear.

  In the above embodiment, the pseudo white LED chip having the luminance distribution shown in FIG. 14 is used as the light source because color rendering can be further improved. However, the present invention is not limited to this, and various light sources are used. For example, even when a pseudo white LED chip having a luminance distribution as shown in FIG. 5C is used, the color rendering of the present invention is made higher than when it is not used by using the color filter of the present invention ( That is, the color reproduction range can be widened) and the NTSC ratio can be increased.

Here, in the liquid crystal display device 10, a light source in which the LED unit 50 is configured by only one pseudo white LED chip 54 is used, but the configuration of the light source is not limited to this.
21A to 21C are front views showing other examples of the light source used in the backlight unit used in the liquid crystal display device of the present invention.
The LED unit 50a of the light source 28a shown in FIG. 21A is composed of one pseudo white LED chip 54 and one blue LED chip 56.
The pseudo white LED chip 54 has the same configuration as the pseudo white LED chip 54 of the light source 28a described above.

The blue LED chip 56 is an LED chip composed of a light emitting diode that emits blue light, and emits blue light from the light emitting surface.
As the blue LED, a GaN light emitting diode, an InGaN light emitting diode, an AlGaN light emitting diode, or the like can be used.
In addition, the pseudo white LED chip 54 and the blue LED chip 56 constituting each LED unit 50a are arranged along the longitudinal direction of the first light incident surface 30d or the second light incident surface 30e of the light guide plate 30 to be described later. 52 is fixed.

The LED unit 50a is configured as described above.
The LED unit 50a emits the mixed white light by mixing the light emitted from the pseudo white LED chip 54 and the light emitted from the blue LED chip 56 with a light guide plate described later.
Here, the LED unit 50a sets the intensity at the peak in the blue wavelength region of the light obtained by mixing the light emitted from the pseudo white LED chip and the light emitted from the blue LED chip as I _0, and the intensity at the wavelength of 580 nm. When I ₅₈₀ , light satisfying I ₅₈₀ / I ₀ > 0.6 is emitted.
Here, the blue wavelength region is a wavelength region of 430 nm or more and 480 nm or less. The peak intensity is the highest intensity in the region.

As described above, an LED unit composed of a pseudo white LED chip and a blue LED chip is used as a light source, and the light emitted from the LED unit is made to satisfy the above-described I ₅₈₀ / I ₀ > 0.6. Thus, even when a pseudo white LED chip is used as the light source, the color reproducibility can be increased and the NTSC ratio can be increased. Thereby, it can be suitably used as a liquid crystal display device for illuminating the liquid crystal display panel.
Since the white light emitted from the pseudo white LED chip 54 and the blue light emitted from the blue LED chip 56 are mixed in the light guide plate 30, white light is emitted from the light emitting surface 24a of the illuminating device body 24. And white light mixed with blue light can be emitted.
Moreover, the color temperature of the light emitted from the light source can be increased by using the pseudo white LED chip and the blue LED chip.
Further, the use of a pseudo white LED chip as a light source can reduce the cost of the apparatus.

  The blue LED used for the pseudo white LED chip and the blue LED used for the blue LED chip are preferably LEDs that emit blue light having different wavelengths. That is, it is preferable to use LEDs that emit light having different color temperatures. By using an LED that emits light of a different wavelength as the blue LED, color reproducibility can be further enhanced. In addition, the color temperature can be easily adjusted, and light having an appropriate color temperature can be emitted with a simple adjustment.

Here, in the backlight unit 20 described above, the LED unit of the light source is one pseudo white LED chip and one blue LED chip. However, the present invention is not limited thereto, and at least one pseudo white LED chip and at least one pseudo white LED chip are used. If one blue LED chip is combined, the number is not limited. Also, the type is not limited to one type, and a plurality of types of pseudo white LED chips and a plurality of types of blue LED chips may be combined. A plurality of types of pseudo white LED chips and one type of blue LED chip may be combined, or a plurality of types of blue LED chips and one type of pseudo white LED chip may be combined.
For example, as shown in FIG. 21B, the LED unit 50b of the light source 28b may be composed of two pseudo white LED chips 54 and one blue LED chip 56, as shown in FIG. The LED unit 50c of the light source 28c may be composed of one pseudo white LED chip 54a, one kind of different pseudo white LED chip 54b, and one blue LED chip 56.

Hereinafter, the light source of the backlight unit used in the liquid crystal display device of the present invention will be described in more detail using specific examples.
First, in Experimental Example I1 of this specific example, a combination of one pseudo white LED chip 54 and one blue LED chip 56 was used as the LED unit 50. In Experimental Example I2, a combination of two pseudo white LED chips 54 and one blue LED chip 56 was used as the LED unit 50a. In Experimental Example I3, a combination of one pseudo white LED chip 54a, one pseudo white LED chip 54b, and one blue LED chip 56 was used as the LED unit 50b.

  Here, the same type of LED chip was used for the pseudo white LED chips 54 and 54a, and the LED chip of a different type from the pseudo white LED chip 54 was used for the pseudo white LED chip 54b. Moreover, the blue LED chip 56 used the same kind of blue LED chip in any of the experimental examples. FIG. 22 is a graph showing the spectral distribution (wavelength dependence) of light emitted from each of the pseudo white LED chip 54 (54a), the pseudo white LED chip 54b, and the blue LED chip 56. Here, in FIG. 22, the horizontal axis is the wavelength [nm], and the vertical axis is the relative intensity.

In Experimental Example I1, Experimental Example I2, and Experimental Example I3, first, the wavelength dependence of the mixed light was measured using the light source configured as described above.
Further, the chromaticity (u ′, v ′ coordinates) of light emitted from the light source and the NTSC ratio were measured using a commonly used RGB color filter.
Here, as the color filter, a color filter used for a commercially available liquid crystal TV panel was used.

For comparison, in Experimental Example I4, when the blue LED chip is not used in the LED unit and only the pseudo white LED chip 54 is used, as Experimental Example I5, the blue LED chip is not used in the LED unit, and the pseudo white color is used. Even when only the LED chip 54b was used, the light chromaticity (u ′, v ′ coordinates) and the NTSC ratio were measured.
Further, as Experimental Example I6 and Experimental Example I7, light chromaticity (u ′, v ′ coordinates) and NTSC ratio when using an LED unit that does not satisfy I ₅₈₀ / I ₀ > 0.6 were also measured.
Here, in Experimental Example I6, a generally used pseudo white LED (Nichia's NFSW036) was used as the LED unit. In Experimental Example I7, a commonly used pseudo white LED (LXCL-PWF manufactured by Philips Lumileds Lighting) and a blue LED (LXML-PR01 manufactured by Philips Lumileds Lighting) were combined and used as an LED unit.

The measured results are shown in Tables 6 and 7. Here, in this measurement, the case where the NTSC ratio was 90% or more was marked as ◎, and the case where the NTSC ratio was less than 90% was marked as x. Here, when the NTSC ratio is 90% or more, it can be suitably used for a high-performance liquid crystal display device.
FIG. 23 shows the spectral distribution (wavelength dependence) of light emitted (emitted) from each of Experimental Example I1, Experimental Example I2, Experimental Example I3, Experimental Example I6, and Experimental Example I7. Here, also in FIG. 23, the horizontal axis is the wavelength [nm] and the vertical axis is the relative intensity. As shown in FIG. 23, it can be seen that Experimental Example I6 and Experimental Example I7 do not satisfy I ₅₈₀ / I ₀ > 0.6.
Further, FIG. 24 shows chromaticity diagrams in the CIEu′v ′ color system of the three primary color points of the light emitted in the case of Experimental Example I1, Experimental Example I2, Experimental Example I3, and Experimental Example I4.

As shown in FIG. 23, FIG. 24, Table 6 and Table 7, use an LED unit composed of a pseudo white LED and a blue LED chip and satisfying I ₅₈₀ / I ₀ > 0.6 as a light source. in (experimental example I1, I2, I3), the case of using the LED unit of a configuration using only pseudo-white LED chips in the light source (experimental example _{I4, I5),} LED units that do not meet the I ₅₈₀ / I 0> 0.6 It can be seen that the NTSC ratio can be made higher than in the case where is used as a light source (Experimental Examples I6 and I7). Further, as shown in Experimental Examples I6 and I7, it is understood that the NTSC ratio does not increase when I ₅₈₀ / I ₀ > 0.6 is not satisfied.

Here, in the above experimental example, a general color filter is used as the color filter. However, the light source is composed of a pseudo white LED and a blue LED chip and satisfies I ₅₈₀ / I ₀ > 0.6. By using the existing LED unit as the light source and using the color filter described above as the color filter, the color reproducibility can be further increased and the NTSC ratio can be further increased.

Moreover, as a light source of the backlight unit used for the liquid crystal display device of this invention, it is also preferable to use the following light sources.
FIGS. 25A to 25C are views showing a part of the light source of the backlight unit shown in FIG. 2, respectively. FIG. 25A is a top view, FIG. 25B is a front view, and FIG. FIG.
As shown in FIGS. 25A to 25C, the light source 28d includes a plurality of LED units 50d and a light source support portion 52.
The LED unit 50 d is composed of one blue LED 60 and a fluorescent member (that is, a phosphor layer) 62. The fluorescent member 62 is a member common to the plurality of blue LEDs 60. That is, in the LED unit 50d, the combination of one blue LED 60 and the corresponding fluorescent member 62 becomes a pseudo white LED chip.

The blue LED 60 is an LED that emits blue light, and has the same configuration as the blue LED described above.
The fluorescent member 62 is a sheet-like member, and is disposed in contact with the light emitting surface 61 of the blue LED 60 of the light source 28d. That is, the fluorescent member 62 is in contact with the light emitting surface 61 at a portion facing the light emitting surface 61 of the blue LED 60 of the light source 28d. Here, the arrangement method of the fluorescent member 62 is not particularly limited. For example, the fluorescent member 62 may be adhered to the light emitting surface 61 with an adhesive or the like, or may be fixed in contact with the light emitting surface 61 with a fixing member or the like.

  The fluorescent member 62 is a sheet-like member having a size that covers the light emitting surfaces 61 of all the blue LEDs 60 disposed on the light source support portion 52, and includes a fluorescent material applying portion 64 and an opening 66. In other words, the fluorescent member 62 is basically formed of the phosphor coating portion 64, and rectangular openings 66 are formed at predetermined intervals. That is, the portion other than the opening 66 of the fluorescent member 62 becomes a phosphor coating portion 64 formed of a fluorescent material.

The phosphor coating part 64 is made of a YAG (yttrium, aluminum, garnet) -based phosphor. When the blue light emitted from the blue LED 60 is transmitted through the phosphor coating portion 64, the YAG-based fluorescent material fluoresces.
In this way, when the blue light emitted from the blue LED 60 is transmitted, the phosphor coating unit 64 generates white light using the blue light emitted from the blue LED 60 and the light emitted by the YAG-based fluorescent substance being fluorescent. Is generated. That is, the light emitted from the blue LED 60 and transmitted through the phosphor coating portion 64 changes from blue light to white light. In other words, the phosphor application unit 64 converts the transmitted blue light into white light.

  The openings 66 are rectangular openings, and as described above, a plurality of openings 66 are formed in a matrix at regular intervals on the sheet-like fluorescent member 62. The opening 66 emits blue light emitted from the blue LED 60 as blue light. That is, the light emitted from the blue LED 60 and transmitted through the opening 66 is emitted as it is as blue light.

  As described above, the fluorescent member 62 has two regions, the region that converts the blue light formed by the phosphor coating portion 64 into white light, and the region that transmits the blue light formed by the opening 66 as blue light. Have.

Here, the fluorescent member 62 having the phosphor application part 64 and the opening 66 is formed by, for example, applying a fluorescent material on the entire surface of the transparent sheet and forming the phosphor application part on the entire transparent sheet, It can be created by cutting out the part.
Further, as another example, a phosphor coating portion may be created by cutting out a portion to be an opening portion of a transparent sheet and forming the opening portion, and then applying a fluorescent material to the transparent sheet.

As described above, by providing the opening 66 in a part of the fluorescent member 62 formed by the phosphor coating part 64, a part of the blue light emitted from the light emitting surface 61 of the blue LED 60 is emitted as blue light. In addition, light having a high color temperature can be emitted from the light exit surface of the light guide plate, the illumination device body, or the backlight unit. That is, an opening is provided in a part of the fluorescent member arranged between the light incident surface (first light incident surface or second light incident surface) of the light guide plate and the light emitting surface of the LED, and the light emitted from the LED is Light that has a high color temperature is emitted from the light exit surface by transmitting the light that passes through some of the openings as blue light and converting the light that passes through the other phosphor-applied parts into white light. Can do. Note that the blue light and white light transmitted through the fluorescent member are mixed when passing through the light guide plate.
In this manner, light having a high color temperature can be emitted from the light source and light having a high color temperature can be emitted from the light emission surface of the backlight unit, whereby a high-quality image or the like can be displayed on the liquid crystal display panel.

  Further, since the ratio of the white light and the blue light transmitted through the fluorescent member 62 can be easily adjusted by changing the ratio of the openings 66 formed in the fluorescent member 62, the color temperature can be easily adjusted. Can be adjusted. Accordingly, light having a desired color temperature can be emitted from the light emission surface of the light guide plate, the illuminating device main body, or the backlight unit with simple adjustment. In addition, the color temperature can be easily adjusted rather than controlling the color temperature based on the thickness of the fluorescent material of the fluorescent member.

Here, in the fluorescent member 62, when the total area of the fluorescent member 62 is Sa and the sum of the areas of the openings 66, that is, the sum of the areas of the blue light transmitting portions is Sap, the relationship between Sa and Sap is as follows. It is preferable that 0.05 ≦ Sap / Sa ≦ 0.40 is satisfied.
By setting Sap / Sa to be 0.05 or more, the color temperature can be set to 7000K or more, and by setting it to 0.40 or less, the color temperature can be set to 35000K or less.

Hereinafter, it demonstrates in detail with a specific example.
In this specific example, the ratio of the sum Sap of the area of the blue light transmitting portion to the total area Sa of the fluorescent member 62, that is, light emitted from the light emitting surface 24a of the backlight unit 20 with various values of Sap / Sa. The luminance distribution and the color temperature of were measured. In this specific example, the change in the color temperature according to the change in Sap / Sa was measured by measuring the light emitted from the light emission surface of the backlight unit 20, but the image display surface of the liquid crystal display device The same tendency is observed when measuring.
FIG. 26 shows the ratio of the sum Sap of the area of the blue light transmitting portion to the total area Sa of the fluorescent member 62, that is, Sap / Sa is 0.05, 0.1, 0.15, 0.2, 0.25. It is a graph which shows the result of having measured the wavelength distribution (spectral spectrum) of the light radiate | emitted from the light-projection surface of a backlight unit when setting it as 0.3, 0.35, 0.4. Here, in the graph of FIG. 26, the vertical axis represents relative intensity and the horizontal axis represents wavelength [nm].
FIG. 27 is a graph showing the relationship between the ratio (Sap / Sa) of the sum Sap of the area of the blue light transmitting portion to the total area Sa of the fluorescent member 62 and the color temperature of the light emitted from the light emitting surface. is there. Here, in the graph of FIG. 27, the vertical axis represents the color temperature [K], and the horizontal axis represents the ratio (Sap / Sa) of the sum Sap of the area of the blue light transmitting portion to the total area Sa of the fluorescent member 62.

As shown in FIG. 27, it can be seen that the color temperature of the light emitted from the light emitting surface can be increased by forming the opening.
Furthermore, it can be seen that the color temperature can be set to various values by changing Sap / Sa as shown in FIG. Specifically, according to this embodiment, the color temperature is adjusted to about 7000 K or more and about 34000 K or less by adjusting the ratio of the opening to the entire fluorescent member between 0.05 ≦ Sap / Sa ≦ 0.40. It can be seen that any color temperature can be achieved. That is, it can be seen that the color temperature can be adjusted only by adjusting the size of the opening.
In addition, as shown in FIG. 26, it can be seen that the color of light emitted from the light exit surface can be adjusted by adjusting the ratio of the opening to the entire fluorescent member.
From the above, the effects of the present invention are clear.

  Here, in the said embodiment, although the fluorescent member was laminated | stacked and arrange | positioned on the light emission surface 61 of blue LED60 of the light source 28d, this invention is not limited to this, The light-incidence surface of a blue LED and the light incidence of a light-guide plate As long as it is between the surfaces (the first light incident surface and the second light incident surface), they may be arranged at any position. For example, the fluorescent member 62 may be disposed in contact with the first light incident surface (or the second light incident surface) of the light guide plate.

Moreover, in this embodiment, although the opening part 66 of the fluorescent member 62 was made into the rectangular shape, it is not limited to this, It can be made into various shapes.
28A to 28C are front views showing other examples of the fluorescent member.
For example, as shown in FIG. 28 (A), the shape of the opening 66a of the fluorescent member 62a may be circular, and the portion excluding the opening 66a of the fluorescent member 62a may be used as the phosphor application portion 64a. Note that the shape of the opening is not limited to a circle, and may be various shapes such as an ellipse, a polygon, and a star.
Further, as shown in FIG. 28B, the shape of the opening 66b of the fluorescent member 62b is a bar shape parallel to one side of the light emitting surface, and the openings 66b are arranged at regular intervals, thereby opening the fluorescent member 62b. The part excluding the part 66b may be used as the phosphor application part 64b.
Furthermore, as shown in FIG. 28C, the shape of the opening 66c of the fluorescent member 62c may be an X-shape, and the portion excluding the opening 66c of the fluorescent member 62c may be a fluorescent material application portion 64c.

Thus, the shape of the opening is not particularly limited, but it is preferable to provide a plurality of openings with respect to the light emitting surface of one blue LED. By providing a plurality of openings on the light emitting surface of one LED chip, it is possible to easily mix blue light and white light generated by being emitted from the blue LED and transmitted through the fluorescent member. Thereby, there is no color unevenness or color unevenness can be emitted from the light emitting surface, and light having a high color temperature can be emitted.
The area of one opening is preferably 0.1 mm ² or more and 0.5 mm ² or less. By setting the area of one opening to 0.1 mm ² or more, it is possible to reliably form the opening in the fluorescent member and to emit blue light from the opening, and to set the area to 0.5 mm ² or less. The light transmitted through the fluorescent member can be mixed efficiently and reliably, and there is no color unevenness or color unevenness from the light emitting surface, and light with a high color temperature can be emitted.

  In the present embodiment, an opening is formed in a part of the fluorescent member, and this opening is a blue light transmitting portion that transmits blue light in a blue color. However, the present invention is not limited to this and is transparent. A fluorescent material is selectively applied to the sheet, and a fluorescent material coated portion and a transparent portion not coated with the fluorescent material are formed on the transparent sheet. It is good also as a blue light transmission part which permeate | transmits as it is.

Moreover, in the said embodiment, although the fluorescent member was made into the sheet | seat shape of 1 sheet, this invention is not limited to this, You may arrange | position a fluorescent member separately for every light emission surface of an LED chip.
FIGS. 29A to 29C are views showing a fluorescent member and a part of a light source as another example of the backlight unit, respectively, (A) is a top view, (B) is a front view, C) is a side view.
The fluorescent members 70 shown in FIGS. 29A to 29C are provided for each blue LED 60, and each fluorescent member 70 is provided in contact with the light emitting surface 61 of the blue LED 60. In the present embodiment, the fluorescent member 70 is bonded to the light emitting surface 61.
The fluorescent member 70 has a phosphor coating portion 72 and an opening 74 and is provided so as to cover the entire light emitting surface 61 of the blue LED 60. The fluorescent member 70 is composed of a phosphor applying part 72 formed by applying a fluorescent substance, and an opening 74 formed as a circular opening having a predetermined diameter at predetermined intervals. That is, the fluorescent member 70 also has a phosphor coating portion 72 that is a region that converts blue light emitted from the blue LED 60 into white light, and an opening 74 that is a region that emits blue light as blue light, that is, blue light transmission. It consists of parts.

As described above, even if the fluorescent member 70 is provided for each blue LED 60, the light emitted from the light emitting surface 61 is emitted from the light emitting surface 61 by arranging the fluorescent member 70 on the entire light emitting surface 61 of the blue LED 60. It passes through (passes through) the coating part 72 or the opening part 74.
Thereby, as described above, a part of the light emitted from the blue LED 60 can be made incident as blue light, and light having a high color temperature can be emitted from the light emitting surface with a simple configuration.

In the case where a fluorescent member is provided for each light emitting surface of the LED chip, the shape of the opening is not particularly limited, and the opening 74 may be circular as shown in FIG. 29A, as shown in FIG. As shown, the opening 74a of the fluorescent member 70a may be rectangular.
In addition, since the fluorescent member can efficiently mix the emitted light and emit light with no color unevenness from the light emitting surface, a plurality of transparent portions are provided for the light emitting surface 61 of one blue LED 60. However, as shown in FIG. 30B, one opening 74 b may be provided for one light emitting surface 61. In other words, one opening 74b may be provided for one fluorescent member 70b. Also in this case, the shape of the transparent portion is not particularly limited. In FIG. 30B, the opening 74b is rectangular, but as shown in FIG. 30C, the opening 74c of the fluorescent member 70c is formed. It is good also as a circle, It is not limited to this, It can be set as various shapes, such as an ellipse, a star shape, a polygon, and X shape.

Here, when the fluorescent member 70 is provided in contact with the light emitting surface of the blue LED, the fluorescent material may be directly applied to the light emitting surface to form the phosphor coating portion and the opening.
Thereby, the position shift of the fluorescent member 70 can be prevented, and furthermore, since the fluorescent member can be formed without using a transparent sheet, the number of members can be reduced and the apparatus configuration can be simplified.

The light source is not limited to the above embodiment, and various LED units using pseudo white LED chips can be used. For example, the light source includes a pseudo white LED chip and a blue LED chip. When the intensity of the peak in the blue wavelength region of the light obtained by mixing the light emitted from the LED and the light emitted from the blue LED chip is I ₀ and the intensity at the wavelength of 580 nm is I ₅₈₀ , I ₅₈₀ / I ₀ > It is good also as a structure which combined the LED unit which satisfy | fills 0.6, and the LED chip of the structure which contacted the fluorescent member 70 which formed the opening part to the light emission surface of blue LED.
That is, as the pseudo white LED chip, an LED chip having a configuration in which the fluorescent member 70 having the opening formed in contact with the light emitting surface of the blue LED is used, and the LED unit is configured with the pseudo white LED chip and the blue LED chip. When the intensity of the peak in the blue wavelength region of the light obtained by mixing the light emitted from the pseudo white LED chip and the light emitted from the blue LED chip is I ₀ and the intensity at a wavelength of 580 nm is I ₅₈₀ , I ₅₈₀ / I ₀ > 0.6 may be satisfied. When the LED unit is configured as described above, the color reproducibility can be further increased, the color temperature can be increased, and the color temperature can be suitably adjusted.
In addition, when combining in this way, as shown in FIG. 29, it is preferable to provide a fluorescent member separately corresponding to blue LED.
Moreover, although it is preferable to use the LED chip of the combination mentioned above as an LED unit, this invention is not limited to this, The LED unit of the various combinations using a pseudo white LED chip can be used. For example, an LED of a color other than a blue LED chip may be used as the auxiliary LED chip.
When the auxiliary LED chip is used in this manner, 0.05 ≦ ls / lm <, where lm is the amount of light emitted from the pseudo white LED chip and ls is the amount of light emitted from the auxiliary LED chip. It is preferable to satisfy 0.5. By satisfying the above range, the color reproducibility can be suitably increased.

  Here, since this embodiment can efficiently emit light having higher luminance from the light exit surface, the side where the light incident surface 30a of the light guide plate 30 intersects the light incident surface becomes a long side and intersects the side surface. However, the present invention is not limited to this, and the light emission surface may be a square shape, the light incident surface side may be a short side, and the side surface side may be a long side.

  In the present embodiment, the light source 28 is disposed only on the light incident surfaces 30d and 30e. However, the present invention is not limited to this, and the light incident surfaces 30d and 30e are as shown in FIGS. The main light source 28 is the light source 28 disposed opposite to the first side surface 30f and the second side surface 30g. The auxiliary light source 29 is provided opposite to the first side surface 30f and the second side surface 30g. And it is good also as a 4th light-incidence surface. By doing in this way, the brightness | luminance of the light radiate | emitted from a light-projection surface can be made higher.

The sub light source 29 basically has the same configuration as that of the main light source 28 described above in the first embodiment except for the arrangement position with respect to the light guide plate 30 and the arrangement density of the LED chips.
The two sub-light sources 29 are arranged to face the third light incident surface 30f and the fourth light incident surface 30g of the light guide plate 30, respectively. Specifically, the sub-light source 29 including the plurality of LED units 50 and the light source support portion 52 is disposed to face the first side surface (third light incident surface) 30f, and the plurality of LED units 50 and the light source support portion are disposed. The sub-light source 29 configured by 52 is arranged to face the second side surface (fourth light incident surface) 30g.

  As described above, the auxiliary light source 29 is disposed at a position facing the third light incident surface 30f and the fourth light incident surface 30g of the light guide plate 30, and light is also incident from the side surface side of the light guide plate 30. Light with higher luminance can be emitted from the light emitting surface 30a, and the amount of light can be increased. Thereby, a large amount of illumination light can be emitted from the light exit surface, the light exit surface can be enlarged, and a large screen can be realized in the liquid crystal display device.

Moreover, you may produce a light-guide plate by mixing a plasticizer in said transparent resin.
Thus, by producing a light guide plate with a material in which a transparent material and a plasticizer are mixed, the light guide plate can be made flexible, that is, a flexible light guide plate. It can be deformed into a shape. Therefore, the surface of the light guide plate can be formed into various curved surfaces.
By making the light guide plate flexible in this way, for example, when a light guide plate or a backlight unit using this light guide plate is used as a display plate for illumination (illumination), it is also mounted on a wall with curvature. Therefore, the light guide plate can be used for more types, a wider range of use in electrical decoration, POP (POP advertisement), and the like.

Here, as the plasticizer, phthalate ester, specifically, dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), di-2-ethylhexyl phthalate (DOP (DEHP)) ), Di-normal octyl phthalate (DnOP), diisononyl phthalate (DINP), dinonyl phthalate (DNP), diisodecyl phthalate (DIDP), phthalic acid mixed ester (C _{6 to} C ₁₁ ) (610P, 711P, etc.) And butylbenzyl phthalate (BBP). In addition to phthalate esters, dioctyl adipate (DOA), diisononyl adipate (DINA), di-normal alkyl adipate (C6, _{8, 10} ) (610A), dialkyl adipate (C7, ₉ ) ( 79A), dioctyl azelate (DOZ), dibutyl sebacate (DBS), dioctyl sebacate (DOS), tricresyl phosphate (TCP), tributyl acetylcitrate (ATBC), epoxidized soybean oil (ESBO), trimellitic acid Examples include trioctyl (TOTM), polyester, and chlorinated paraffin.

  As described above, the backlight unit according to the present invention has been described in detail. However, the present invention is not limited to the above embodiment, and various improvements and modifications are made without departing from the gist of the present invention. Also good.

For example, a mixing unit formed of a material having a refractive index close to that of the light guide plate 30 may be disposed between the light guide plate 30 and the light source (the light source 28 and / or the sub light source 29). Further, a part of the light incident surface and / or side surface of the light guide plate may be formed of a material having a smaller refractive index than other portions.
By reducing the refractive index of the portion where the light emitted from the light source is incident, the light emitted from the light source can be incident more efficiently and the light utilization efficiency can be further increased. .

  Further, for example, a plurality of light guide plates may be arranged in parallel at a position where the side surfaces of the light guide plates face each other, and one light emitting surface may be formed by the plurality of light guide plates. In this case, it is good also as a structure which arrange | positions a sublight source only to the side surface of the side which is not adjacent to the other light-guide plate of the light-guide plate of both ends.

  Moreover, since light with a medium and high luminance distribution can be emitted from the light emitting surface, the light guide plate preferably satisfies the various ranges described above, but it is also preferable to use a light guide plate in the following ranges.

The light guide plate has a scattering cross-sectional area of the scattering particles contained in the light guide plate 30 as Φ, and the length from the light incident surface of the light guide plate to the position where the thickness in the direction orthogonal to the light exit surface is maximized in the light incident direction. In this embodiment, L _{G is} the length of half of the light incident direction of the light guide plate (the direction perpendicular to the first light incident surface 30d of the light guide plate 30; hereinafter also referred to as “optical axis direction”). When the density of scattering particles (number of particles per unit volume) contained in the optical plate 30 is N _p and the correction coefficient is K _C , the value of Φ · N _p · L _G · K _C is 1.1 or more. And the relationship of the correction coefficient K _C being 0.005 or more and 0.1 or less is satisfied. Since the light guide plate 30 includes scattering particles that satisfy such a relationship, the illumination light can be emitted from the light exit surface with uniform and less uneven brightness.

In general, the transmittance T when a parallel light beam is incident on an isotropic medium is expressed by the following formula (1) according to the Lambert-Beer rule.
T = I / I ₀ = exp (−ρ · x) (1)
Here, x is a distance, I ₀ is incident light intensity, I is outgoing light intensity, and ρ is an attenuation constant.

The attenuation constant ρ is expressed by the following equation (2) using the scattering cross-sectional area Φ of particles and the number of particles N _p per unit volume contained in the medium.
ρ = Φ · N _p (2)
Therefore, the length of the half of the optical axis direction of the light guide plate when the L _G, the light extraction efficiency E _out is given by the following equation (3). Here, half the length L _G of the optical axis of the light guide plate, the length from one of the light incident surface of the light guide plate 30 in a direction perpendicular to the light incident surface of the light guide plate 30 to the center of the light guide plate 30 .
Furthermore, the light extraction efficiency and are, with respect to the incident light, the fraction of light reaching the position spaced the length L _G in the optical axis direction from the light incident surface of the light guide plate, for example, the light guide plate 30 shown in FIG. 2 In this case, it is a ratio of light reaching the center of the light guide plate (a position having a half length in the optical axis direction of the light guide plate) with respect to light incident on the end face.
E _out ∝exp (−Φ · N _p · L _G ) (3)

Here the formula (3) applies to a space of limited size, to introduce a correction coefficient K _C for correcting the relationship between the expression (1). The compensation coefficient K _C is a dimensionless compensation coefficient empirically obtained where light optical medium of limited dimensions propagates. Then, the light extraction efficiency E _out is expressed by the following formula (4).
_{E out = exp (-Φ · N} p · L G · K C) ··· (4)

According to the equation (4), when the value of Φ · N _p · L _G · K _C is 3.5, the light extraction efficiency E _out is 3%, and Φ · N _p · L _G · K _C When the value of is 4.7, the light extraction efficiency E _out is 1%.
From this result, it can be seen that the light extraction efficiency E _out decreases as the value of Φ · N _p · L _G · K _C increases. Since light is scattered as it travels in the direction of the optical axis of the light guide plate, the light extraction efficiency E _out is considered to be low.

Therefore, it can be seen that the larger the value of Φ · N _p · L _G · K _C is, the more preferable property is for the light guide plate. In other words, by increasing the value of Φ · N _p · L _G · K _C , it is possible to reduce the light emitted from the surface facing the light incident surface and increase the light emitted from the light emission surface. it can. That is, by increasing the value of _{Φ · N p · L G ·} K C, ( hereinafter also referred to as "light use efficiency".) Optically percentage is emitted from the light emitting surface for light incident on the incident surface of the high can do. Specifically, by setting 1.1 or the value of _{Φ · N p · L G ·} K C, the light use efficiency can be 50% or more.
Here, when the value of Φ · N _p · L _G · K _C is increased, the illuminance unevenness of the light emitted from the light exit surface 30a of the light guide plate 30 becomes remarkable, but Φ · N _p · L _G · K _C By making the value of 8.2 or less, the illuminance unevenness can be suppressed to a certain value (within an allowable range). Note that the illuminance and the luminance can be handled in substantially the same manner. Therefore, in the present invention, it is presumed that luminance and illuminance have the same tendency.
From the above, the value of Φ · N _p · L _G · K _C of the light guide plate used in the backlight unit used in the liquid crystal display device of the present invention satisfies the relationship of 1.1 or more and 8.2 or less. Is preferable, and more preferably 2.0 or more and 7.0 or less. The value of _{Φ · N p · L G ·} K C is more preferably as long as 3.0 or more, most preferably, not less than 4.7.
The correction coefficient K _C is preferably 0.005 or more and 0.1 or less.

Hereinafter, the light guide plate will be described in more detail with specific examples. In the following specific examples, the luminance and the like were measured using an LED unit composed of one type of LED chip as the light source. However, an LED unit having a pseudo white LED chip and a blue LED chip may also be used. Basically the same trend.
First, the scattering cross section Φ, the particle density N _p , the length L _G of the light guide plate half in the optical axis direction, and the correction coefficient K _C are set to various values, and the values of Φ · N _p · L _G · K _C are different. About each light-guide plate, the light use efficiency was calculated | required by computer simulation, and also illumination intensity nonuniformity was evaluated. Here, the illuminance unevenness [%] is the maximum illuminance of light emitted from the light emitting surface of the light guide plate and I _Max, a minimum illuminance and I _Min, Average illuminance when the I _Ave [(I _Max - I _Min ) / I _Ave ] × 100.
The measurement results are shown in Table 8 below. In the determination of Table 8, the case where the light use efficiency is 50% or more and the illuminance unevenness is 150% or less is indicated by ◯, and the case where the light use efficiency is less than 50% or the illuminance unevenness is more than 150% is indicated by x.
Further, in FIG. 32, the relationship between the value of Φ · N _p · L _G · K _C and the light utilization efficiency (the ratio of the light emitted from the light exit surface to the light incident on the light entrance surface) was measured. Results are shown.

As shown in Table 8 and FIG. 32, by setting Φ · N _p · L _G · K _C to 1.1 or more, the light use efficiency is increased, specifically, the light use efficiency is set to 50% or more. It can be seen that by setting it to 8.2 or less, the illuminance unevenness can be reduced to 150% or less.
Further, by making Kc 0.005 or more, the light use efficiency can be increased, and by setting it to 0.1 or less, the illuminance unevenness of the light emitted from the light guide plate can be reduced. Recognize.

Then, the particle density N _p of the particles which kneaded or dispersed in the light guide plate creates various values of the light guide plate was measured illuminance distribution of light emitted from each position of the light emitting surface of each light guide plate . In this exemplary embodiment, other conditions except for the particle density N _p, specifically, the scattering cross section [Phi, half the length of the optical axis direction of the light guide plate L _G, the correction coefficient K _C, the light guide plate The shape and the like were the same value. Accordingly, in the present _{embodiment, Φ · N p · L G} · K C changes in proportion to the particle density _{N p.}
FIG. 33 shows the result of measuring the illuminance distribution of the light emitted from the light exit surface for the light guide plates having various particle densities in this way. In FIG. 33, the vertical axis represents illuminance [lx], and the horizontal axis represents the distance (light guide length) [mm] from one light incident surface of the light guide plate.

Furthermore, the illuminance unevenness when the maximum illuminance of the light emitted from the side wall of the light guide plate of the measured illuminance distribution is I _Max , the minimum illuminance is I _Min , and the average illuminance is I _Ave [(I _Max −I _Min ) / I _Ave ] × 100 [%] was calculated.
FIG. 34 shows the relationship between the calculated illuminance unevenness and the particle density. In FIG. 34, the vertical axis represents illuminance unevenness [%], and the horizontal axis represents particle density [pieces / m ³ ]. FIG. 34 also shows the relationship between light utilization efficiency and particle density, where the horizontal axis is the particle density and the vertical axis is the light utilization efficiency [%].

As shown in FIGS. 33 and 34, when the particle density is increased, that is, Φ · N _p · L _G · K _C is increased, the light use efficiency is increased, but the illuminance unevenness is also increased. It can also be seen that when the particle density is lowered, that is, when Φ · N _p · L _G · K _C is reduced, the light utilization efficiency is reduced, but the illuminance unevenness is also reduced.
Here, by the _{Φ · N p · L G ·} K C 1.1 or more 8.2 or less, the light use efficiency of 50% or more and illuminance unevenness of 150% or less. By setting the illuminance unevenness to 150% or less, the illuminance unevenness can be made inconspicuous.
_{That, Φ · N p · L G} · K C to be to less than 1.1 and not greater than 8.2 yields light use efficiency above a certain level, and illuminance unevenness also seen that it is possible to reduce.

  In addition, since the backlight unit can be made larger and light with an appropriate luminance distribution (and / or illuminance distribution) can be emitted with high light utilization efficiency, a rectangular light emission can be used as the light guide plate of the backlight unit. Two light incident surfaces which are disposed at positions facing each other and include two long sides facing each other, and the light emission surfaces from the two light incident surfaces toward the center of the light emission surface, respectively. It is preferable to have a shape and configuration including two symmetrical inclined surfaces whose distance from the surface is far away, a curved portion that joins these two inclined surfaces, and scattering particles that scatter light propagating inside the two inclined surfaces. The present invention is not limited to this, and can be used for light guide plates having various shapes. For example, it can be used for a backlight unit and a liquid crystal display device using a light guide plate in which scattering particles are not dispersed, and can also be used for a backlight unit and a liquid crystal display device using a flat light guide plate.

Next, the light guide plate having a flat light exit surface of the backlight unit shown in FIG. 2 will be specifically described. In the following examples, the luminance and the like were measured using an LED unit composed of one type of LED chip as the light source, but the basic case is also possible when an LED unit having a pseudo white LED chip and a blue LED chip is used. Tend to be similar.
As described above, in the liquid crystal display device of the present invention, suitable light utilization efficiency can be obtained by appropriately setting the maximum thickness, minimum thickness, particle diameter, and particle concentration of the light guide plate.
Using the light source 28 and the light guide plate 30 configured as shown in FIGS. 2A and 2B, the light guide length [mm] of the light guide plate 30, its shape, that is, the maximum thickness [mm] and the minimum thickness [mm]. By changing the taper [°], the center radius R [mm], the particle diameter [μm] and the particle concentration [wt%] of the scattering fine particles dispersed in the light guide plate 30, two light incident surfaces 30d of the light guide plate 30 and The light utilization efficiency [%] indicating the ratio of the light emitted from the light emitting surface 30a to the light incident from 30e and the luminance distribution of the light emitted from the light emitting surface 30a are obtained, and the peripheral portion of the light emitting surface 30a That is, the medium altitude [%] of the luminance distribution of the light emitting surface 30a indicating the ratio of the luminance of the light emitted from the central portion of the light emitting surface 30a to the luminance of the light emitted from the vicinity of the light incident surfaces 30d and 30e is obtained. It was.

(Experimental example II)
As Experimental Example II, the maximum thickness [mm], the minimum thickness [mm], and the particle diameter [μm] when the light guide length L [mm] of the light guide plate 30 corresponding to a screen size of 37 inches is L = 480 mm. When the particle concentration [wt%] is variously changed as shown in Table 9 and Table 10, taper [°], central radius (curvature radius of curvature) R [mm], light utilization efficiency [%], Middle altitude [%] was calculated. The results are shown in Table 9 and Table 10.
Here, Table 9 shows Reference Examples II1 to II6 for Experimental Example II, and Table 10 shows Measurement Examples II1 to II6 for Experimental Example II.

As is clear from Table 9 and Table 10, in Reference Examples II1 to II6, the particle diameter [μm] and the particle concentration [wt%] all satisfy the preferred limiting range of the present invention, and the maximum thickness Since the thickness [mm] and the minimum thickness [mm] also satisfy the preferred limited range of the present invention, the light utilization efficiency [%] is 61% or more and higher than 55%. Is 19% to 23%, and satisfies the preferred limited range required by the present invention of more than 0% and 25% or less.
On the other hand, since the measurement example II1 has a particle concentration higher than the preferred limited range of the present invention, the phenomenon is similar to that of a flat plate, and thus a medium-high luminance distribution cannot be realized.

In measurement example II2, both the maximum thickness [mm] and the minimum thickness [mm] are larger than the upper limit values of 6.0 mm and 3.0 mm of the preferred limited range of the present invention, and light penetrates through. For this reason, the light utilization efficiency does not satisfy the limited range of 55% or more, and the weight is too heavy to be suitable as an optical member for a liquid crystal TV.
In measurement example II3, the taper angle is smaller than 0.1 ° from the preferred limited range of the present invention, the center radius R is large, and it is not suitable for molding, and the light utilization efficiency is 55% or more. Medium-high distribution cannot be achieved with particle concentration.

Measurement Example II4 has a large central radius R, is not suitable for molding, is similar to a flat plate, and cannot achieve a light utilization efficiency of 55% or more at a particle concentration that achieves a medium-high luminance distribution.
In Measurement Example II5, the particle diameter is smaller than the preferred limited range of the present invention and the light utilization efficiency is good, but a medium-high luminance distribution cannot be realized. In Measurement Example II6, the particle diameter is smaller than the preferred limited range of the present invention. A large, medium and high luminance distribution can be realized, but the light utilization efficiency is low.

(Experimental Example III)
As Experimental Example III, the maximum thickness [mm] and the minimum thickness [mm] when the light guide length L [mm] of the light guide plate 30 corresponding to the screen size of 42 inches and 46 inches is L = 560 mm and 590 mm, When the particle diameter [μm] and particle concentration [wt%] are variously changed as shown in Table 11 and Table 12, taper [°], central radius (curvature radius of curvature) R [mm], utilization of light Efficiency [%] and intermediate altitude [%] were determined. The results are shown in Table 11 and Table 12.
Here, Table 11 shows Reference Examples III1 to III4 for Experimental Example III, and Table 12 shows Measurement Examples III1 to III3 for Experimental Example III.

As is clear from Table 11 and Table 12, all of Reference Examples III1 to III4 of Experimental Example III satisfy the preferred limited range of the present invention in terms of particle diameter [μm] and particle concentration [wt%] Moreover, since the maximum thickness [mm] and the minimum thickness [mm] also satisfy the preferred limited range of the present invention, the light utilization efficiency [%] is 59% to 61% and higher than 55%, The intermediate altitude [%] is also 14% to 15%, and satisfies the preferred limited range required by the present invention of more than 0% and 25% or less.
On the other hand, since the measurement examples III1 and III2 have a particle concentration higher than the preferred limited range of the present invention, the phenomenon is the same as that of a flat plate, and thus a medium-high luminance distribution cannot be realized.
In measurement example III3, the maximum thickness [mm] is larger than the upper limit value of 6.0 mm, which is a preferable limited range of the present invention, the maximum thickness becomes larger than necessary, and the distribution becomes higher than necessary. In addition to being too much, the weight becomes too heavy and is not suitable as an optical member for a liquid crystal TV.

(Experimental example IV)
As Experimental Example IV, when the light guide length L [mm] of the light guide plate 30 corresponding to the screen size of 52 inches and 57 inches is L = 660 mm and 730 mm, the maximum thickness [mm], the minimum thickness [mm], When the particle diameter [μm] and the particle concentration [wt%] are variously changed as shown in Tables 13 and 14, the taper [°], the central part (curved part radius) R [mm], and the light utilization efficiency [%] ], Intermediate altitude [%] was determined. The results are shown in Table 13 and Table 14.
Here, Table 13 shows Reference Examples IV1 to IV2 for Experimental Example IV, and Table 14 shows Measurement Examples IV1 to IV4 for Experimental Example IV.

As is clear from Table 13 and Table 14, in Reference Examples IV1 to IV2 of Experimental Example IV, the particle diameter [μm] and the particle concentration [wt%] all satisfy the preferred limited range of the present invention, Moreover, since the maximum thickness [mm] and the minimum thickness [mm] also satisfy the preferred limited range of the present invention, the light utilization efficiency [%] is 60% to 61% and higher than 55%, The intermediate altitude [%] is also 14% to 14.2%, which satisfies the preferred limited range required by the present invention of more than 0% and 25% or less.
On the other hand, since the measurement example IV1 has a particle concentration higher than the preferable limited range of the present invention, the phenomenon is similar to that of a flat plate, and thus a medium-high luminance distribution cannot be realized.

Further, in Measurement Example IV2, since the particle concentration is lower than the preferable limited range of the present invention, light penetrates and passes, and thus the light utilization efficiency does not satisfy 55% or more.
Further, in measurement examples IV3 and IV4, the taper angle is smaller than 0.1 ° of the upper limit value of the preferred limited range of the present invention, the taper is too small, and the central radius R is too large, which is not suitable for molding. In Measurement Example IV3, a medium-high distribution cannot be realized at a particle concentration at which light utilization efficiency is 55% or more. Measurement Example IV4 is the same as a flat plate, and the light use efficiency does not satisfy 55% or more at a particle concentration that achieves a medium-high luminance distribution.

(Experiment V)
As Experimental Example V, the maximum thickness [mm] and the minimum thickness [mm] when the light guide length L [mm] of the light guide plate 30 corresponding to the screen size of 52 inches and 57 inches is L = 660 mm and 730 mm, When the particle diameter [μm] and particle concentration [wt%] are variously changed as shown in Table 15 and Table 16, taper [°], central radius (curvature radius of curvature) R [mm], utilization of light Efficiency [%] and intermediate altitude [%] were determined. The results are shown in Table 15 and Table 16.
Here, Table 15 shows reference examples V1 to V4 for Experimental Example V, and Table 16 shows measurement examples V1 to V5 for Experimental Example V.

As is clear from Table 15 and Table 16, all of Reference Examples V1 to V4 of Experimental Example V satisfy the preferred limited range of the present invention in terms of particle diameter [μm] and particle concentration [wt%] Moreover, since the maximum thickness [mm] and the minimum thickness [mm] also satisfy the preferred limited range of the present invention, the light utilization efficiency [%] is 57% to 68%, which is higher than 55%, The intermediate altitude [%] is also 11% to 24%, which satisfies the preferred limited range required by the present invention of more than 0% and 25% or less.
On the other hand, in the measurement example V1, since the particle concentration is lower than the preferred limited range of the present invention, the light penetrates and penetrates, so that the light utilization efficiency does not satisfy 55% or more.

In the measurement example V2, the maximum thickness [mm] and the minimum thickness [mm] are both larger than the upper limit values 6.0 mm and 3.0 mm of the preferable limited range of the present invention, and light penetrates through. Therefore, the light utilization efficiency does not satisfy the limited range of 55% or more, and the weight is too heavy, which is not suitable as an optical member for a liquid crystal TV.
Further, in measurement example V3, the maximum thickness [mm] is smaller than the lower limit value 1.0 mm of the preferred limited range of the present invention, and the central radius R is too large, exceeding the preferred limited range of the present invention. If the particle concentration is not suitable for molding and the light utilization efficiency is 55% or more, a medium-high distribution cannot be realized.
In measurement example V4, the particle diameter is smaller than the preferred limited range of the present invention and the light utilization efficiency is good, but a medium-high luminance distribution cannot be realized. In measurement example V5, the particle diameter is smaller than the preferred limited range of the present invention. A large, medium and high luminance distribution can be realized, but the light utilization efficiency is low.

From the above results, the reference example has an appropriate shape according to each light guide length range of the light guide plate in any of the experimental examples, and has a maximum thickness [mm] and a minimum thickness [mm]. ], The taper [°], the central radius R [mm], the particle diameter [μm] and the particle concentration [wt%] of the scattering particles to be dispersed satisfy the preferred limited range of the present invention, and the light utilization efficiency [%]. Is 55% or more, and the medium to high altitude [%] is more than 0% and 25% or less.
On the other hand, in the measurement examples, in any of the experimental examples, the light utilization efficiency [%] does not satisfy 55% or more because any of the above requirements falls outside the preferable limited range of the present invention. The intermediate and high grades [%] do not satisfy more than 0% and not more than 25% and cannot exhibit excellent characteristics.
From the above, the effect of the present invention is clear.

It is a schematic perspective view which shows one Embodiment of the liquid crystal display device of this invention. It is the II-II sectional view taken on the line of the liquid crystal display device shown in FIG. It is an enlarged front view which expands and shows a part of color filter. (A) is a partially omitted plan view showing a light source and a light guide plate of the backlight unit shown in FIG. 2, and (B) is a cross-sectional view taken along line BB of (A). (A) is a perspective view which shows schematic structure of the light source of the backlight unit shown in FIG. 2, (B) is a graph which shows an example of the spectrum distribution of a pseudo white LED chip, (C) is ( It is a schematic perspective view which expands and shows one pseudo white LED chip which comprises the light source shown to A). It is a schematic perspective view which shows the shape of the light-guide plate shown in FIG. (A) is a cross-sectional schematic diagram of the light guide plate shown in FIG. 2, and (B) is a partially enlarged cross-sectional view of the light guide plate shown in (A). It is a graph which shows the relationship between the taper angle of the light-guide plate used for the backlight unit used for the liquid crystal display device of this invention, and luminance distribution. It is a graph which shows the relationship between the particle diameter and particle concentration [wt%] of the scattering fine particles disperse | distributed to the light-guide plate used for the backlight unit used for the liquid crystal display device of this invention. (A) And (B) is a graph which shows the relationship between the particle diameter and particle concentration [wt%] of the scattering fine particle disperse | distributed to the light-guide plate used for the backlight unit used for the liquid crystal display device of this invention, respectively. . (A) And (B) is a graph which shows the relationship between the particle diameter and particle concentration [wt%] of the scattering fine particle disperse | distributed to the light-guide plate used for the backlight unit used for the liquid crystal display device of this invention, respectively. . It is a flowchart which shows an example of the design method of the light-guide plate used for the backlight unit used for the liquid crystal display device of this invention. It is a graph which shows the relationship between the particle | grain density | concentration [wt%] of a light-guide plate used for the backlight unit used for the liquid crystal display device of this invention, light utilization efficiency [%], and middle altitude degree [%]. It is a graph which shows the spectrum distribution of the LED chip used for the measurement. It is a graph which shows the spectrum distribution of a color filter. It is a graph which shows the spectrum distribution of a color filter. It is a graph which shows the spectrum distribution of a color filter. It is a graph which shows the spectrum distribution of a color filter. It is a graph which shows the three primary color points of a measurement result in the chromaticity diagram in a CIEu'v 'color system. It is a graph which shows the three primary color points of a measurement result in the chromaticity diagram in a CIEu'v 'color system. (A)-(C) are front views which show another example of the light source used for the backlight unit used for the liquid crystal display device of this invention, respectively. It is a graph which shows the spectrum distribution of the LED chip used for the measurement. It is a graph which shows spectrum distribution of a measurement result. It is a graph which shows the three primary color points of a measurement result in the chromaticity diagram in a CIEu'v 'color system. (A)-(C) are the figures which respectively show the fluorescent member of the backlight unit shown in FIG. 2, and a part of light source, (A) is a top view, (B) is a front view, (C ) Is a side view. It is a graph which shows the result of having measured the wavelength distribution of the light radiate | emitted from the light-projection surface of the backlight unit which made Sap / Sa various values. It is a graph which shows the relationship between the ratio of the sum Sap of the area of a blue light transmission part with respect to the whole area Sa of a fluorescent member, and the color temperature of the light radiate | emitted from a light-projection surface. (A)-(C) are front views which show another example of a fluorescent member, respectively. (A)-(C) is a figure which shows a fluorescent member of another example of a backlight unit, and a part of light source, respectively, (A) is a top view, (B) is a front view, (C) FIG. (A)-(C) are front views which show another example of a fluorescent member, respectively. (A) is a partial abbreviation top view which shows the light source and light-guide plate of another example of the backlight unit used for the liquid crystal display device of this invention, (B) is BB sectional drawing of (A). It is. It is a diagram showing the results of measuring the relationship between _{Φ · N p · L G ·} K C and light use efficiency. It is a figure which shows the result of having each measured the illumination intensity of the light radiate | emitted from each light guide from which particle density differs. It is a figure which shows the relationship between light use efficiency, illumination intensity nonuniformity, and particle density. It is a graph which shows the illumination intensity distribution of the front direction of the conventional flat light-guide plate.

DESCRIPTION OF SYMBOLS 10 Liquid crystal display device 12 Liquid crystal display panel 14 Drive unit 20 Backlight unit (planar illumination device)
24 Illuminating device body 24a, 30a Light exit surface 26 Housing 28, 28a, 28b Light source 29 Sub light source 30 Light guide plate 30b First inclined surface 30c Second inclined surface 30d First light incident surface 30e Second light incident surface 30f First Side (third light incident surface)
30g Second side (fourth light incident surface)
32 Optical member unit 32a Diffusion sheet 32b Prism sheet 32c Diffusion sheet 34 Reflector plate 36 Upper guide reflector 38 Lower guide reflector 42 Lower housing 44 Upper housing 46 Reinforcement member 48 Support member 49 Power storage 50, 50a, 50b, 50c LED unit 52 Light source support 54, 54a, 54b Pseudo white LED chip 56 Blue LED chip 58 Light emitting surface 60 Blue LED
61 Light emitting surface 62 Fluorescent member 64 Phosphor coating portion 66 Opening 80 Color filter 82R Red filter 82G Green filter 82B Blue filter 83 Cut filter α 2 bisector c Optical axis distance between light source and light guide plate

Claims (25)

A light guide plate having a light incident surface on which light is incident and a light emitting surface that emits light incident from the light incident surface, a blue LED that emits blue light disposed opposite to the light incident surface, and the blue LED A planar illumination device having a light source having at least one LED unit including at least one pseudo-white LED unit having a yellow phosphor layer disposed between the LED and the light incident surface;
A liquid crystal comprising a color filter disposed on the light emitting surface of the planar illumination device and comprising a red filter having at least a red color element, a green filter having a green color element, and a blue filter having a blue color element. A panel,
The liquid crystal display device, wherein the color filter has a wavelength cut filter that removes light having a wavelength of 570 nm or more and 590 nm or less arranged in a region corresponding to the green filter.   The liquid crystal display device according to claim 1, wherein the wavelength cut filter removes light having a wavelength of 570 nm or more.   3. The liquid crystal display device according to claim 1, wherein the red filter has a wavelength of 585 nm or more and less than 600 nm at which the transmittance starts to increase sharply.   The liquid crystal display device according to claim 1, wherein the green filter has a wavelength with a maximum transmittance of greater than 500 nm and less than or equal to 515 nm.   The liquid crystal display device according to claim 1, wherein the blue filter has a wavelength with a maximum transmittance of greater than 440 nm and less than or equal to 455 nm. A light guide plate having a light incident surface on which light is incident and a light emitting surface that emits light incident from the light incident surface, a blue LED that emits blue light disposed facing the light incident surface, and the blue LED A planar illumination device having a light source having at least one LED unit including at least one pseudo-white LED unit having a yellow phosphor layer disposed between the LED and the light incident surface;
A liquid crystal comprising a color filter disposed on the light emitting surface of the planar illumination device and comprising a red filter having at least a red color element, a green filter having a green color element, and a blue filter having a blue color element. A panel,
The liquid crystal display device according to claim 1, wherein the red filter has a wavelength of 585 nm or more and 600 nm or less where the transmittance starts to increase sharply.   The liquid crystal display device according to claim 6, wherein the green filter has a wavelength with a maximum transmittance of greater than 500 nm and less than 515 nm.   The liquid crystal display device according to claim 6, wherein the blue filter has a wavelength with a maximum transmittance of greater than 440 nm and less than or equal to 455 nm. A light guide plate having a light incident surface on which light is incident and a light emitting surface that emits light incident from the light incident surface, a blue LED that emits blue light disposed opposite to the light incident surface, and the blue LED A planar illumination device having a light source having at least one LED unit including at least one pseudo-white LED unit having a yellow phosphor layer disposed between the LED and the light incident surface;
A liquid crystal comprising a color filter disposed on the light emitting surface of the planar illumination device and comprising a red filter having at least a red color element, a green filter having a green color element, and a blue filter having a blue color element. A panel,
The green filter has a wavelength with a maximum transmittance of greater than 500 nm and less than or equal to 515 nm.   The liquid crystal display device according to claim 9, wherein the blue filter has a wavelength with a maximum transmittance of greater than 440 nm and less than or equal to 455 nm. A light guide plate having a light incident surface on which light is incident and a light emitting surface that emits light incident from the light incident surface, a blue LED that emits blue light disposed facing the light incident surface, and the blue LED A planar illumination device having a light source having at least one LED unit including at least one pseudo-white LED unit having a yellow phosphor layer disposed between the LED and the light incident surface;
A liquid crystal comprising a color filter disposed on the light emitting surface of the planar illumination device and comprising a red filter having at least a red color element, a green filter having a green color element, and a blue filter having a blue color element. A panel,
The blue filter has a wavelength with a maximum transmittance of greater than 440 nm and less than or equal to 455 nm.   The phosphor layer includes a phosphor coating part that converts blue light emitted from the light emitting surface of the blue LED into white light, and emits blue light emitted from the light emitting surface as blue light. The liquid crystal display device according to claim 1, comprising a light transmission portion.   The liquid crystal display device according to claim 12, wherein the blue light transmission portion is formed of a transparent film or an opening. The LED unit further includes at least one blue LED chip disposed in the vicinity of the pseudo white LED and emitting blue light,
In the pseudo white LED chip, the phosphor layer is disposed on the surface of the blue LED,
When the intensity of the peak in the blue wavelength region of the light obtained by mixing the light emitted from the pseudo white LED chip and the light emitted from the blue LED chip is I ₀ and the intensity at a wavelength of 580 nm is I ₅₈₀ , I The liquid crystal display device according to claim 1, wherein ₅₈₀ / I ₀ > 0.6 is satisfied.   The liquid crystal display device according to claim 14, wherein the blue LED chip emits blue light having a wavelength dependency different from that of the blue LED constituting the pseudo white LED chip.   The liquid crystal display device according to claim 14, wherein the LED unit has two types of pseudo white LED chips having different emission wavelengths. The light source includes a plurality of the LED units and a support that supports the plurality of LED units,
The liquid crystal display device according to claim 1, wherein the plurality of LED units are arranged in a line on one surface of the support.   The light guide plate includes a rectangular light exit surface, two light incident surfaces each including two opposing long sides of the light exit surface, and disposed at positions facing each other, and the light from the two light incident surfaces. Scattering particles that have two symmetrical inclined surfaces whose distances from the light emitting surface become farther toward the center of the emitting surface, and curved portions that join these two inclined surfaces, and scatter light propagating in the inside. The liquid crystal display device according to claim 1, comprising: The light guide plate is
The light guide length between the two light incident surfaces is 280 mm or more and 320 mm or less,
The particle diameter of the scattering particles is 4.0 μm or more and 12.0 μm or less, the concentration of the scattering particles is 0.1 wt% or more and 0.76 wt% or less, and
The particle size and concentration of the scattering particles are 6 points (4.0, 0... 0) in a graph in which the horizontal axis is the particle size (μm) of the scattering particles and the vertical axis is the concentration (wt%) of the scattering particles. 1), (4.0, 0.32), (7.0, 0.14), (7.0, 0.5), (12.0, 0.25) and (12.0, 0. 76),
The utilization efficiency of light indicating the ratio of light incident from the two light incident surfaces being emitted from the light exit surface is 55% or more,
The medium to altitude of the luminance distribution of the light emitting surface, which indicates the ratio of the luminance of the light emitted from the central portion of the light emitting surface to the luminance of the light emitted from the vicinity of the light incident surface of the light emitting surface, exceeds 0%. The liquid crystal display device according to claim 18, which is 25% or less. The light guide plate is
The light guide length between the two light incident surfaces is 480 mm or more and 500 mm or less,
The particle size of the scattering particles is 4.0 μm or more and 12.0 μm or less, the concentration of the scattering particles is 0.02 wt% or more and 0.22 wt% or less, and
The particle size and concentration of the scattering particles are 6 points (4.0, 0) in a graph in which the horizontal axis is the particle size (μm) of the scattering particles and the vertical axis is the particle concentration (wt%) of the scattering particles. .02), (4.0, 0.085), (7.0, 0.03), (7.0, 0.12), (12.0, 0.06) and (12.0,0 .22) within the area surrounded by
The utilization efficiency of light indicating the ratio of light incident from the two light incident surfaces being emitted from the light exit surface is 55% or more,
The medium to altitude of the luminance distribution of the light emitting surface, which indicates the ratio of the luminance of the light emitted from the central portion of the light emitting surface to the luminance of the light emitted from the vicinity of the light incident surface of the light emitting surface, exceeds 0%. The liquid crystal display device according to claim 18, which is 25% or less. The light guide plate is
The light guide length between the two light incident surfaces is 515 mm or more and 620 mm or less,
The particle size of the scattering particles is 4.0 μm or more and 12.0 μm or less, the concentration of the scattering particles is 0.015 wt% or more and 0.16 wt% or less, and
The particle size and concentration of the scattering particles are 6 points (4.0, 0) in a graph in which the horizontal axis is the particle size (μm) of the scattering particles and the vertical axis is the particle concentration (wt%) of the scattering particles. .015), (4.0, 0.065), (7.0, 0.02), (7.0, 0.09), (12.0, 0.035) and (12.0,0 .16) within the area surrounded by
The utilization efficiency of light indicating the ratio of light incident from the two light incident surfaces being emitted from the light exit surface is 55% or more,
The medium to altitude of the luminance distribution of the light emitting surface, which indicates the ratio of the luminance of the light emitted from the central portion of the light emitting surface to the luminance of the light emitted from the vicinity of the light incident surface of the light emitting surface, exceeds 0%. The liquid crystal display device according to claim 18, which is 25% or less. The light guide plate is
The light guide length between the two light incident surfaces is 625 mm or more and 770 mm or less,
The particle size of the scattering particles is 4.0 μm or more and 12.0 μm or less, the concentration of the scattering particles is 0.01 wt% or more and 0.12 wt% or less, and the particle size and concentration of the scattering particles are In the graph in which the horizontal axis represents the particle size (μm) of the scattering particles and the vertical axis represents the particle concentration (wt%) of the scattering particles, 6 points (4.0, 0.01), (4.0, 0 .05), (7.0, 0.01), (7.0, 0.06), (12.0, 0.02) and (12.0, 0.12) ,
The utilization efficiency of light indicating the ratio of light incident from the two light incident surfaces being emitted from the light exit surface is 55% or more,
The medium to altitude of the luminance distribution of the light emitting surface, which indicates the ratio of the luminance of the light emitted from the central portion of the light emitting surface to the luminance of the light emitted from the vicinity of the light incident surface of the light emitting surface, exceeds 0%. The liquid crystal display device according to claim 18, which is 25% or less. The light guide plate is
A light guide plate including scattering particles that scatter light propagating therein,
The light guide length between the two light incident surfaces is 785 mm or more and 830 mm or less,
The particle size of the scattering particles is 4.0 μm or more and 12.0 μm or less, the concentration of the scattering particles is 0.008 wt% or more and 0.08 wt% or less, and the particle size and concentration of the scattering particles are: In the graph in which the horizontal axis represents the particle diameter (μm) of the scattering particles and the vertical axis represents the particle concentration (wt%) of the scattering particles, 6 points (4.0, 0.008), (4.0, 0 .03), (7.0, 0.009), (7.0, 0.04), (12.0, 0.02) and (12.0, 0.08) ,
The utilization efficiency of light indicating the ratio of light incident from the two light incident surfaces being emitted from the light exit surface is 55% or more,
The medium to altitude of the luminance distribution of the light emitting surface, which indicates the ratio of the luminance of the light emitted from the central portion of the light emitting surface to the luminance of the light emitted from the vicinity of the light incident surface of the light emitting surface, exceeds 0%. The liquid crystal display device according to claim 18, which is 25% or less. The light guide plate is
The thickness of the light incident surface with the smallest thickness is 0.5 mm or more and 3.0 mm or less,
The thickness of the center of the curved portion where the thickness is the largest is 1.0 mm or more and 6.0 mm or less,
The curvature radius of the curved portion is 1,500 mm or more and 45,000 mm or less,
The liquid crystal display device according to any one of claims 19 to 23, wherein a taper of the inclined surface with respect to a line parallel to the light emitting surface is not less than 0.1 ° and not more than 2.2 °. The light guide plate has a scattering cross-sectional area of the scattering particles of Φ, a density of the scattering particles of N _p , a correction coefficient of K _C , and a thickness in a direction perpendicular to the light exit surface from the light incident surface in the light incident direction. satisfying but the length to the position of maximum when the _{L G,} the inequality _{1.1 ≦ Φ · N p · L} G · K C ≦ 8.2 and 0.005 ≦ _{K C} ≦ 0.1 The liquid crystal display device according to claim 18.

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