KR20170134190A - Liquid crystal display device, light source device, and method of manufacturing light source device - Google Patents

Abstract

The present invention relates to a light source device capable of making a light emitted to a liquid crystal display panel highly pure and extending a color reproduction range, and a method for manufacturing the light source device. The light source device comprises: a light source supplying a light emitted to the liquid crystal display panel; and a dielectric multilayer film having a structure in which dielectric layers with different refractive indexes are alternately stacked and making a light emitted from a light source pure in a plurality of primary color wave lengths. The light source is discharged in a direction at a polar angle with respect to a normal line of an emitting surface of the light source and has a light distribution performance in which the amount of light passing through the dielectric multilayer film is maximum when the polar angle _M > 0 is satisfied. The dielectric multilayer film has optimized light passing performance so that the light is incident at the polar angle _M with respect to a normal line of the stacked surface of the dielectric multilayer film and passes through the dielectric multilayer film.

Description

[0001] The present invention relates to a liquid crystal display device, a light source device, and a manufacturing method of the light source device,

The present invention relates to a light source device for supplying light for illuminating a liquid crystal panel of a liquid crystal display device and a method of manufacturing the light source device.

BT, which regulates the color reproduction range of UHD TV (Ultra-High Definition Television) by ITU (International Telecommunications Union) in 2012. 2020 standard was recommended. However, the color reproduction range of a typical liquid crystal display device is. 2020 is limited to about 60% to 75% with respect to the color reproduction range, and the color reproduction range is expected to be further enlarged.

The color reproduction range of the liquid crystal display device can be enlarged by, for example, making the light of the backlight unit illuminating the liquid crystal panel from the backside of the liquid crystal panel into high pure color. In Patent Document 1, an optical filter containing a dye absorbing light in a wavelength range of 440 to 510 nm or 570 to 605 nm is disposed between the backlight unit and the liquid crystal panel, so that the light from the backlight unit is highly colored. Further, in Patent Document 2, a dielectric multi-layered film in which a high refractive index layer and a low refractive index layer are alternately stacked is arranged between a backlight unit and a liquid crystal panel, so that light from the backlight unit is colored high. In Patent Document 3, a dielectric multi-layer film which blocks a specific wavelength is arranged between the LED light source and the light guide plate of the backlight unit, thereby making the light of the backlight unit high-order.

Patent Document 1: JP-A-2002-40233 Patent Document 2: JP-A-2005-234132 Patent Document 3: JP-A-2008-85232 Patent Document 4: Japanese Patent Application Laid-Open No. 2007-183525

However, the following problems exist in the prior art.

In Patent Document 1, the dye of the optical filter becomes high temperature by absorbing light of a specific wavelength band, and the adjacent liquid crystal panel also becomes high temperature. In addition, since the light absorbing dye of the optical filter is an organic matter, when the light is continuously irradiated for a long time, the dye is aged with time and the light absorption characteristic is changed.

In Patent Document 2, light from the backlight unit is incident on the liquid crystal panel at various angles, but there is an angle dependency in the light transmission characteristics of the dielectric multilayer film. Therefore, the brightness and color of the external appearance of the liquid crystal panel change in the viewing angle direction, and the viewing angle characteristics of the liquid crystal display device are deteriorated.

Also in Patent Document 3, the light from the LED light source is incident on the light guide plate at various angles, but the light transmission characteristic of the dielectric multilayer film has an angle dependency. Therefore, the light transmission wavelength range of the dielectric multi-layer film can not be narrowed due to the angle dependency and widened, so that the light transmission characteristic for reducing the light of the backlight unit is lowered.

A light source device according to the present invention includes a dielectric multilayer film having a structure in which a light source for supplying light for illuminating a liquid crystal panel and dielectric layers having different refractive indices are alternately laminated and coloring the light emitted from the light source to a plurality of primary color wavelengths And the light source has a light distribution characteristic in which the amount of light that is radiated in a direction forming a polar angle &thetas; with the normal direction of the light emitting surface of the light source and passes through the dielectric multilayer film becomes maximum at a polar angle & amp _; thetas; _M > 0 DEG, The multilayered film is characterized in that it has a light transmission characteristic which is optimized so that light passing through the dielectric multilayer film is incident on the direction of the polar angle & amp _; thetas; _M with respect to the normal direction of the laminated surface of the dielectric multilayered film.

A method of manufacturing a light source device according to the present invention is a method of manufacturing a light source device having a structure in which a light source for supplying light for illuminating a liquid crystal panel and a dielectric layer having a different refractive index are alternately laminated and light emitted from the light source is colored with a plurality of primary color wavelengths Wherein a quantity of light passing through the dielectric multi-layer film radiated in a direction forming a polar angle &thetas; with the normal direction of the light emitting surface of the light source is maximum at a polar angle & amp _; thetas; _M > 0 DEG And a dielectric multilayer film having a light transmission characteristic optimized to minimize light passing through the dielectric multilayer film from a direction forming a polar angle & amp _; thetas; _M with respect to a normal direction of a laminate surface of the dielectric multilayer film, And the light emitting surface of the light source are parallel to each other.

According to the present invention, it is possible to obtain a light source device and a method of manufacturing a light source device capable of increasing the color reproduction range by high-ordering the light illuminating the liquid crystal panel.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a color reproduction range by a general liquid crystal display device, and FIG. 2020 and the xy chromaticity diagram shown together with the color reproduction range.
2 is a view showing light passing characteristics of a general dielectric multilayer film.
3 is a schematic view showing a configuration of a liquid crystal display device according to the first embodiment.
4 is a diagram showing light passing characteristics of a general color filter.
5 is a diagram showing the light emission spectrum of the light source of the light source device according to the first embodiment.
6 is a diagram showing light distribution characteristics of the light source of the light source device according to the first embodiment.
7 is a diagram showing the angle dependence of the light distribution characteristic of the light source of the light source device according to the first embodiment.
8 is a diagram showing light passing characteristics of the dielectric multilayer film of the light source device according to the first embodiment.
9 is a diagram showing a color reproduction range by the liquid crystal display device using the light source device according to the first embodiment.
10 is a schematic view showing a configuration of a liquid crystal display device according to the second embodiment.
11 is a diagram showing the light emission spectrum of the light source of the light source device according to the second embodiment.
12 is a diagram showing a color reproduction range by the liquid crystal display device using the light source device according to the second embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments, and can be appropriately changed without departing from the gist of the present invention. In the following drawings, those having the same functions are denoted by the same reference numerals, and the description thereof may be omitted or simplified.

≪ First Embodiment >

Hereinafter, a liquid crystal display device according to the first embodiment will be described with reference to Figs. 1 to 9. Fig. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the color reproduction range of a general liquid crystal display device, with reference to BT. 2020 and the xy chromaticity diagram shown together with the color reproduction range. The peak position of the triangle in the xy chromaticity diagram shows the purity of the three primary colors of red (R), green (G), and blue (B) reproducible by a liquid crystal display or a standard.

As shown in Fig. 1, the color reproduction range R1 of a general liquid crystal display device is represented by BT. The area of the triangle becomes smaller than the color reproduction range R0 defined by 2020. This is a common liquid crystal display device. In order to reproduce the 2020 standard, it means that three primary colors of R (red) / G (green) / B (blue) need to be further colored. If the three primary colors represented by the triangle vertices of the xy chromaticity diagram can be high-ordered, it is possible to reproduce a clearer color by combining the high-order three primary colors.

The area of the color reproduction range R1 by the general liquid crystal display device shown in Fig. 20 to 20% of the color reproduction range (R0) area. BT. In order to reproduce the color reproduction range specified by 2020, for example, it is necessary to increase the color reproduction range by further increasing the color of light illuminating the liquid crystal panel from the back surface.

In order to brighten the light illuminating the liquid crystal panel, for example, an optical filter or a dielectric multi-layer film is used and light of wavelengths of R (red) / G (green) / B And light of wavelengths other than the three primary colors may be removed or blocked. However, as described above, there is a problem that the optical filter is deteriorated with the passage of time because the heat generated by the light absorbing dye is large. Further, there is a problem that the dielectric multi-layer film has an angle dependency of the light transmission characteristic.

2 is a diagram showing light passing characteristics of a general dielectric multilayer film. The dielectric multilayer film has a structure in which dielectric layers having different refractive indexes are alternately stacked, and blocks light having a specific frequency. The light transmission characteristics of the dielectric multilayer film shown in Fig. 2 are optimized so that the following condition is satisfied with respect to light incident from the normal direction (0 deg) of the laminate surface.

When the wavelengths of the three primary colors R (red), G (green) and B (blue) are respectively 610/530/470 nm, the light transmittance at the wavelengths of these three primary colors is All became more than 80%. And has a minimum transmittance of 5% or less at wavelengths of 470 to 530 nm and 560 to 610 nm. Thus, the dielectric multilayer film shown in FIG. 2 can pass light of three primary colors having wavelengths of 470, 530, and 610 nm, block light other than the three primary colors, and colorize the incident light into three primary color wavelengths.

However, there is an angle dependency in the light transmission characteristics of the dielectric multilayer film. As shown in Fig. 2, the light transmission characteristic of a general dielectric multi-layer film shifts toward the short wavelength side as the light is incident on the laminate surface at a larger angle. Due to the angle dependence of the light transmission characteristics, the light transmission characteristics of the dielectric multilayer film shown in Fig. 2 can not satisfy the above-described optimization conditions for light incident at a large angle (> 15 deg) with respect to the lamination plane . As a result, there has been a problem that the dielectric multilayer film can not effectively colorize incident light diagonally. The present invention aims to solve such a problem.

3 is a schematic view showing a configuration of a liquid crystal display device according to the first embodiment. The liquid crystal display device shown in Fig. 3 includes a liquid crystal panel 1 and a backlight unit 2. Fig. A light diffusion sheet, a prism sheet, or the like may be disposed between the liquid crystal panel 1 and the backlight unit 2.

The liquid crystal panel 1 includes a pair of glass substrates 12a and 12b facing each other with a liquid crystal layer 11 interposed therebetween. A plurality of electrodes 10 are provided on the glass substrate 12a on the backlight unit 2 side of the glass substrates 12a and 12b. A control unit (not shown) of the liquid crystal display device applies a voltage to the electrode 10 of the glass substrate 12a to generate an electric field parallel to the liquid crystal layer 11 and rotate the liquid crystal molecules to display the liquid crystal display .

In the liquid crystal panel 1, polarizing plates 14a and 14b are provided on the outer sides of the glass plates 12a and 12b, respectively. The direction of the polarization axis of the polarizers 14a and 14b is set so that light illuminated from the backlight unit 2 passes or is blocked when a voltage is applied to the electrode 10. [ For example, the directions of the polarization axes of the polarizers 14a and 14b shown in Fig. 3 are orthogonal to each other.

Between the glass substrate 12b of the liquid crystal panel 1 and the liquid crystal layer 11, a color filter 15 is provided. The color filter 15 passes light in the R (red) / G (green) / B (blue) three primary color wavelengths of the light illuminated from the backlight unit 2. FIG. 4 shows an example of the light passing characteristic of the general color filter 15.

The backlight unit 2 is an edge light type backlight and includes a light source 22 having an LED element 26 at the end of the light guide plate 21. [ The light source 22 supplies light for illuminating the liquid crystal panel 1 through the light guide plate 21. The dielectric multi-layer film 23 colors the light emitted from the light source 22 to three primary color wavelengths. In the edge light method, since the light source 22 is provided at the end portion of the light guide plate 21, the area illuminated by the light source 22 can be reduced, and the backlight unit 2 can be downsized. A light reflecting sheet or the like for reflecting the light supplied to the light guide plate 21 toward the liquid crystal panel 1 may be disposed on the side opposite to the liquid crystal panel 1 of the backlight unit 2. [

5 is a diagram showing the light emission spectrum of the light source 22 of the light source device according to the first embodiment. 6 is a diagram showing light distribution characteristics of the light source 22 of the light source device according to the first embodiment. The light source 22 of the present embodiment has the LED element 26 and the phosphor 27 as shown in Fig. LED element 26 and emits blue light, by the phosphor 27 mainly composed of _{YAG (Y 3 Al 3 O 12} ) , some light is converted into yellow light.

As a result, the light emitted by the LED element 26 and the light emitted by the phosphor 27 are mixed to give a white color. The LED element 26 may emit light having a wavelength shorter than 470 nm, which is a blue primary color wavelength. As shown in Fig. 5, the light emission spectrum of the light source 22 has a sharp peak at the blue wavelength emitted by the LED element 26, and a gentle peak at the yellow wavelength.

It is known that the light distribution characteristic in the case where the light emitted by the LED element 26 is radiated by the phosphor 27 as described above is substantially in the form of lambertian. Fig. 6 shows the light distribution characteristics in the lamp bar. The Lambertian luminous intensity distribution is a luminous intensity distribution characteristic in which the intensity I of the light emitted in the solid angle direction forming the polar angle &thetas; with the normal direction of the light emitting surface (emission surface) of the light source 22 is light distribution characteristic proportional to the cosine of the polar angle & ). Where I _O is the intensity of light emitted in the direction of the polar angle θ = 0.

The amount of light radiated in the spherical micro-angle dS = sin? D? D? Centering on the light source 22 in the spherical coordinates having the normal axis of the light emitting surface of the light source 22 as the polar axis can be obtained by the following equation (2) .

When the above equation (2) is integrated with the azimuth angle? = 0 to 2 ?, the quantity of light I '(?) Radiated in the range of the micro-pole dθ shown by oblique lines in FIG. 6 is obtained. The result is the following equation (3).

(3) has a maximum at a polar angle & amp _; thetas; _M = 45 DEG. That is, the amount of light I '(&thetas;) emitted in the range of the micro-pole d &thetas; on the spherical surface shown by oblique lines in FIG. 6 is found to be maximum in the polar angle & amp _; thetas; _M = 45 DEG.

However, the amount of light actually supplied to the light guide plate 21 in the amount of light emitted by the light source 22 is not the amount of light I '(?) Passing through the solid angle on the spherical surface shown in FIG. 6, (&Amp;thetas;) that is incident on the dielectric multilayer film 23 and is incident on the dielectric multilayer film 23. Thus, by adding correction to the above-mentioned formula (2), the quantity of light I (?) Passing through the dielectric multilayer film 23 from the direction forming the polar angle? With respect to the normal direction of the laminated surface of the dielectric multilayer film 23 is obtained.

The intensity I of light is inversely proportional to the square of the distance r from the light source 22. The intensity I of the light on the incident surface of the so a r _O = rcosθ as shown the minimum distance to Speaking r _O, Fig. 6, the dielectric multilayer film 23 to the dielectric multilayer film 23 from the light source 22 is cos ² is proportional to?. The above equation (4) is obtained by multiplying the above equation (2) by the factor of cos ² & thetas ;.

Furthermore, the amount of light that passes through the dielectric multilayer film 23 and is supplied to the light guide plate 21 in the amount of light incident on the surface of the dielectric multilayer film 23 at a polar angle? Is a component perpendicular to the laminate surface of the dielectric multilayer film 23, cos [theta] times. When the cos? Factor is further multiplied by the above equation (4), the following equation (5) is obtained.

When the above equation (5) is integrated with the azimuth angle? = 0 to 2?, The light amount I (?) Passing through the dielectric multi-layer film 23 incident on the micro-polar angle d? Range on the surface of the dielectric multilayer film 23 shown in Fig. Is obtained. The result is the following equation (6).

Equation (6) generally has a maximum at a polar angle & amp _; thetas; _M = 25 DEG. That is of a dielectric multi-layer film 23 is laminated is incident from a direction forming a polar angle θ with respect to the direction normal to the light amount I (θ) passing through the dielectric multilayer film 23 in the plane of, the substantially polar angle θ _M = 25 ° shown in Figure 6 In the direction of the arrow.

7 is a diagram showing the angle dependency of the light distribution characteristic of the light source 22 of the light source device according to the first embodiment. 7 shows an actually measured value of the amount of light incident on the dielectric multi-layer film 23 at a polar angle &thetas; with respect to the normal direction of the laminated surface of the dielectric multilayer film 23 among the light emitted from the light source 22, as a histogram. In FIG. 7, the theoretical value of the quantity of light calculated by integrating the above equation (6) into the polar angle &thetas; is shown by a line graph. The integrated value ∫I (θ) dθ of the light quantity incident from the range of the polar angle θ of 10 ° width in both measured values and theoretical values was measured or calculated at intervals of 10 °.

From FIG. 7, it can be seen that the measured luminous intensity of the light source 22 generally agrees with the theoretical value of the angle dependency of the Lambertian luminous intensity distribution based on the above equation (6). It can be seen that the amount of light that is incident from the direction of the polar angle θ = 20 ° to 30 ° and passes through the dielectric multilayer film 23 is the largest. Also, it can be seen that the polar angle θ _M at which the amount of light is maximized in the Lambert cyan light distribution is generally 25 °. It is considered that the error between the measured value and the theoretical value shown in Fig. 7 is the fact that the light distribution characteristic of the actual light source 22 is not the ideal lamb cyan light distribution.

Thus, the light distribution characteristic of the light source 22 has angle dependency. On the other hand, as described above, the light transmission characteristic of the dielectric multilayer film 23 also has an angle dependency. Although any angle dependence is a negative factor in the color reproducibility of the liquid crystal display device, there is a possibility that a positive synergy effect can be obtained by matching the angle dependency of both sides. Therefore, in the present embodiment, it is considered to optimize the light transmission characteristics of the dielectric multilayer film 23 in accordance with the light distribution characteristics of the light source 22.

8 is a diagram showing light passing characteristics of the dielectric multilayer film 23 of the light source device according to the first embodiment. A dielectric multi-layer film 23 shown in Figure 8, has a low refractive index layer are alternately laminated structure in the high refractive index layers and SiO ₂ as a main material for the TiO ₂ the main material. The light transmission characteristics of the dielectric multi-layered film 23 are optimized so that the above-described optimization conditions are satisfied with respect to light incident from an angle of 25 degrees with respect to the laminated surface.

That is, when the wavelengths of the three primary colors R (red), G (green), and B (blue) are set to 610/530/470 nm, the dielectric multilayered film 23 has a 25- The light transmittance at the wavelengths of the three primary colors with respect to the light incident from the light source is 80% or more. And has a minimum transmittance of 5% or less at wavelengths of 470 to 530 nm and 560 to 610 nm.

The dielectric multilayer film 23 having such a light passing property is formed by applying a known technique (see, for example, Patent Document 4) to a conventional dielectric multilayer film having the light passing property shown in Fig. 2, It is possible to manufacture by shifting the characteristic to the long wavelength side. As a result, the dielectric multilayer film 23 of the present embodiment allows light of three primary colors having wavelengths of 470, 530, and 610 nm to pass therethrough while blocking light other than the three primary colors, It can be changed.

The conditions for optimizing the light transmission characteristics of the dielectric multi-layered film 23 may have a minimum in any of the wavelength ranges of 470 to 530 nm or 560 to 610 nm instead of having a minimum in both wavelength ranges of 470 to 530 nm and 560 to 610 nm . The minimum of the wavelength range is not necessarily 5% or less, but is preferably 5% or less.

As described above, the light transmission characteristic of the dielectric multilayer film 23 of the present embodiment is optimized for light incident from the direction of the polar angle &amp;thetas; = 25 where the amount of incident light is maximized as shown by the solid line in Fig. On the other hand, as shown by the dotted line or the broken line in FIG. 8, light incident from a direction of a polar angle? <15 ° or a polar angle?> 35 ° having a small amount of incident light is not optimized.

9 is a view showing a color reproduction range by the liquid crystal display device using the light source device according to the first embodiment. Fig. 9 shows the case of BT. In addition to the color reproduction range R0 specified by the liquid crystal display device of the present embodiment in addition to the color reproduction range R0 defined by the liquid crystal display device of the present embodiment and the color reproduction range R1 by the general liquid crystal display device having no dielectric multilayer film, Respectively. 9 shows an actually measured value of the color reproduction range R3 when the light transmission characteristic of the dielectric multilayer film is not optimized in accordance with the light distribution characteristic of the light source 22 as a comparative example. The color reproduction range was determined by using a light source 22 having light distribution characteristics shown in Fig. 7, and the display colors of R (red) / G (green) / B (blue) .

The color reproduction range R2 of the liquid crystal display device of the present embodiment shown by the solid line in Fig. 9 is a color reproduction range R2 between the light source 22 and the light guide plate 21, that is, the dielectric multilayer film 23 ) Were placed and measured. The light transmission characteristic of the dielectric multilayer film 23 is optimized in accordance with the light distribution characteristic of the light source 22. [ The area of the color reproduction range R2 by the liquid crystal display device of this embodiment is BT. Of the color reproduction range (R0) defined by 2020 was 77.3%. On the other hand, the area of the color reproduction range R1 by the conventional liquid crystal display device without the dielectric multilayer film 23 is BT. (67.1%) of the color reproduction range (R0) area defined by 2020.

In this embodiment in which the light transmission characteristic of the dielectric multilayer film 23 is optimized in accordance with the light distribution characteristics of the light source 22, 2020 standard. However, the color reproduction range can be widened as compared with the conventional method in which the dielectric multi-layer film 23 is not disposed.

On the other hand, the color reproduction range R3 shown by the one-dot chain line in FIG. 9 was measured by disposing a dielectric multilayer film having the light transmission characteristics shown in FIG. 2 between the light source 22 and the light guide plate 21. The light transmission characteristics of the conventional dielectric multi-layer film shown in Fig. 2 are not optimized in accordance with the light distribution characteristics of the light source 22. Fig. The area of the color reproduction range R3 is BT. 20.5% of the color reproduction range (R0) specified by the present invention.

In the configuration in which the light transmission characteristics of the dielectric multilayer film are not optimized in accordance with the light distribution characteristics of the light source 22, the color reproduction range is narrower than the configuration without the dielectric multilayer film. This is because the dielectric multilayer film shown in Fig. 2 is optimized not only in the direction of the polar angle &amp;thetas; = 25 degrees at which the light source is maximized but in the direction of the polar angle &amp;thetas; Is removed by the angle dependency of the dielectric multilayer film.

As described above, the light source of this embodiment has a light distribution characteristic in which the amount of light passing through the dielectric multi-layer film radiated in the direction of the polar angle &amp;thetas; with the normal direction of the light emitting surface of the light source becomes maximum at the polar angle & amp _; thetas; _M &gt; 0 DEG. In addition, the dielectric multilayer film of the present embodiment has a light transmission characteristic that is optimized so that light passing through the dielectric multilayer film incident on the direction of the polar angle & amp _; thetas; _M with respect to the normal direction of the laminated surface of the dielectric multilayer film is minimized. As a result, it is possible to obtain a light source device capable of increasing the color reproduction range by increasing the color of light illuminating the liquid crystal panel.

Further, in the above description, the light source 22 has the luminous intensity distribution in the lambscent of the formula (1), but the present embodiment is not limited thereto. The light source 22 has a light distribution characteristic in which the amount of light that is radiated in the direction that makes the polar angle θ with the normal direction of the light emitting surface of the light source 22 and passes through the dielectric multilayer film 23 becomes maximum at the extremum θ _M > It should be. 6, the laminated surface of the dielectric multilayer film 23 and the light emitting surface of the light source 22 are arranged so as to be parallel to each other. However, the present invention is not limited to this arrangement.

In the above description, the dielectric multilayer film 23 has a structure in which a high refractive index layer mainly composed of TiO ₂ and a low refractive index layer mainly composed of SiO ₂ are alternately laminated, but the present invention is not limited thereto. As the high-refraction material, ZnS, CeO ₂ , ZrTiO ₄ , HfO ₂ , Ta ₂ O ₅ , ZrO ₂ or the like may be used, and as the low refractive material, MgF ₂ or the like may be used. Further, the dielectric multi-layer film 23 is designed to colorize the light emitted by the light source 22 to three primary color wavelengths of 610/530/470 nm, but it may be colored at other three primary color wavelengths, It can be reconciled.

&Lt; Second Embodiment >

Next, the liquid crystal display device and the light source device according to the second embodiment will be described with reference to Figs. 10 to 12. Fig. 10 is a schematic view showing a configuration of a liquid crystal display device according to the second embodiment. The liquid crystal display device of this embodiment shown in Fig. 10 differs from the liquid crystal display device of the first embodiment shown in Fig. 3 in that a KSF fluorescent substance (fluorophosphor fluorescent material) is used in place of the TAG fluorescent substance. The other configuration is the same as that of the first embodiment, and a description thereof will be omitted. The differences from the first embodiment will be described below.

11 is a diagram showing the light emission spectrum of the light source 22b of the light source device according to the second embodiment. The light source 22b of the present embodiment has an LED element 26 and a phosphor 27b as shown in Fig. The LED element 26 emits blue light, and some light is converted into red light by the phosphor 27b whose main component is KSF.

As a result, the light emitted by the LED element 26 and the light emitted by the phosphor 27b are mixed to produce a white color. As shown in Fig. 11, the light emission spectrum of the light source 22b has a sharp peak at the blue wavelength emitted by the LED element 26, and also has a peak in the red band and the green band. By having the light source 22b having a peak in the green band as described above, it is possible to reproduce a wider color reproduction range than the liquid crystal display of the first embodiment.

12 is a diagram showing a color reproduction range by the liquid crystal display device using the light source device according to the second embodiment. Fig. 12 shows the structure of BT. In addition to the color reproduction range R0 specified by the liquid crystal display device of the present embodiment in addition to the color reproduction range R0 defined by the liquid crystal display device of the present embodiment and the color reproduction range R1 by the general liquid crystal display device having no dielectric multilayer film, Respectively. 12 shows a measured value of the color reproduction range R3 as a comparative example when the light transmission characteristic of the dielectric multilayer film is not optimized in accordance with the light distribution characteristic of the light source 22b. The color reproduction range was determined by using a light source 22b having the light distribution characteristics shown in Fig. 11 and measuring the display colors of R (red) / G (green) / B (blue) .

The color reproducibility range R2 of the liquid crystal display device of the present embodiment shown by the solid line in Fig. 12 is a color reproduction range R2 between the light source 22b and the light guide plate 21, the dielectric multilayer film 23 ) Were placed and measured. The light transmission characteristic of the dielectric multilayer film 23 is optimized in accordance with the light distribution characteristics of the light source 22b. The area of the color reproduction range R2 by the liquid crystal display device of this embodiment is BT. (84%) of the color reproduction range (R0) area defined by 2020. On the other hand, the area of the color reproduction range R1 by the conventional liquid crystal display device without the dielectric multilayer film 23 is BT. (75%) of the color reproduction range (R0) area defined by 2020.

In this embodiment in which the light transmission characteristic of the dielectric multilayer film 23 is optimized in accordance with the light distribution characteristics of the light source 22b, 2020 standard, the color reproduction range can be increased as compared with the conventional method in which the dielectric multilayer film 23 is not disposed. Further, by using a KSF fluorescent material in place of the YAG fluorescent material, the color reproduction range can be further expanded as compared with the liquid crystal display device of the first embodiment.

On the other hand, the color reproduction range R3 shown by the one-dot chain line in FIG. 12 is obtained by arranging a dielectric multi-layer film having the light transmission characteristics shown in FIG. 2 between the light source 22b and the light guide plate 21. The light transmission characteristic of the conventional dielectric multi-layer film shown in Fig. 2 is not optimized in accordance with the light distribution characteristic of the light source 22b. The area of the color reproduction range R3 is BT. (75%) of the color reproduction range (R0) area defined by 2020.

In the configuration in which the light transmission characteristics of the dielectric multilayer film are not optimized in accordance with the light distribution characteristics of the light source 22, the color reproduction range is the same as that of the configuration without the dielectric multilayer film, and no improvement is seen. This is because the dielectric multilayer film shown in Fig. 2 is optimized not only in the direction of the polar angle &amp;thetas; = 25 degrees at which the light amount is the maximum but in the direction of the polar angle &amp;thetas; Is removed by the angle dependency of the dielectric multilayer film.

As described above, the light source device of the present embodiment includes a KSF fluorescent substance in place of the YAG fluorescent substance. This makes it possible to obtain a light source device capable of further expanding the color reproduction range in addition to the same effects as those of the first embodiment.

<Other Embodiments>

The foregoing embodiments are merely illustrative of the embodiments of the present invention, and the technical scope of the present invention should not be construed as being limited thereto. That is, the present invention can be carried out in various forms without departing from the technical idea or main features thereof.

1: liquid crystal panel 2: backlight unit
10: electrode 11: liquid crystal layer
12a and 12b: glass substrates 14a and 14b: polarizers
15: color filter 21: light guide plate
22: light source 23: dielectric multilayer film
26: LED element 27: phosphor

Claims (10)

A light source for supplying light for illuminating the liquid crystal panel,
And a dielectric multilayer film having a structure in which dielectric layers having different refractive indexes are alternately stacked and coloring the light emitted from the light source to a plurality of primary color wavelengths,
The light source, is irradiated to achieve a normal direction and the polar angle θ of the light emitting surface of the light source direction, the amount of light passing through the dielectric multilayer film, the polar angle θ _M> has the light distribution characteristics is maximum in the 0 °,
Wherein the dielectric multilayer film has a light transmission characteristic that is optimized so that light passing through the dielectric multilayer film is incident on the direction of the polar angle & amp _; thetas; _M with respect to the normal direction of the laminated surface of the dielectric multilayer film.
The method according to claim 1,
Wherein the laminated surface of the dielectric multilayer film and the light emitting surface of the light source are arranged to be parallel to each other.
3. The method according to claim 1 or 2,
Wherein the plurality of primary color wavelengths are 470, 530, and 610 nm,
The light transmission characteristic of the dielectric multilayer film is such that the light transmittance at the plurality of primary color wavelengths with respect to the light incident on the laminate surface of the dielectric multilayer film from the direction of the polar angle & amp _; thetas; _M is 80% or more and 470 to 530 nm or A light source device having a minimum light transmittance in a wavelength range of 560 to 610 nm.
The method of claim 3,
Wherein the light transmission characteristic of the dielectric multilayer film has a minimum light transmittance in a wavelength range of 470 to 530 nm and 560 to 610 nm.
The method according to claim 3 or 4,
Wherein a minimum value of the light transmittance is 5% or less.
6. The method according to any one of claims 1 to 5,
Wherein the light source includes a YAG fluorescent material or a KSF fluorescent material, and the light distribution characteristic of the light source satisfies 20 °? The polar angle? _M ? 30 °.
7. The method according to any one of claims 1 to 6,
Wherein the light source includes an LED element emitting light of a shorter wavelength than 470 nm.
8. The method according to any one of claims 1 to 7,
Wherein the dielectric multilayer film has a structure in which a high refractive index layer mainly composed of TiO ₂ and a low refractive index layer mainly composed of SiO ₂ are alternately laminated.
A light source for supplying light for illuminating the liquid crystal panel,
A dielectric multilayer film having a structure in which dielectric layers having different refractive indexes are alternately stacked and coloring light emitted from the light source to a plurality of primary color wavelengths,
Is radiated to achieve the normal direction and the polar angle θ of the light emitting surface of the light source direction and the light source having a luminous intensity distribution property the amount of light passing through the dielectric multilayer film, the polar angle θ _M> at 0 ° is a maximum,
Layer dielectric multilayer film having a light transmission characteristic which is optimized so that the light passing through the dielectric multilayer film is incident on the direction of the polar angle & amp _; thetas; _M with respect to the normal direction of the laminate surface of the dielectric multilayer film,
And arranging the laminated surface of the dielectric multilayer film and the light emitting surface of the light source so as to be parallel to each other.
A liquid crystal display device comprising an edge light type backlight unit in which the light source device according to any one of claims 1 to 8 is disposed at an end portion of a light guide plate.

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