JP2001185087A - Fluorescent lamp, back light and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device which can satisfy color specifications of European Broadcasting Union. SOLUTION: A back light device 14 is assembled to a liquid crystal panel 12 to constitute a liquid crystal display device 11. The liquid crystal panel 12 provides red, green, and blue color filters at every pixels of liquid crystal. A fluorescent lamp FL of the back light device 14 is three wavelength type having a red phosphor, a green phosphor and a blue phosphor, and a half width value of the blue phosphor is not more than 40 nm. Also, light L1 emitted from the fluorescent lamp FL has a color temperature of not less than 8,500 K and deviation of not more than 0.015. Light L2 emitted from the back light device 14 has color temperature of not less than 7000 K and deviation of not more than 0.01.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fluorescent lamp used for a color display device, a backlight device using the fluorescent lamp, and a liquid crystal display device using the backlight device.

[0002]

2. Description of the Related Art Conventionally, as described in, for example, Japanese Patent Application Laid-Open No. 9-33920, a liquid crystal display device having a flat liquid crystal panel and a backlight device for illuminating the liquid crystal panel from the back is known. Have been. In the liquid crystal panel, for example, substrates each having a transparent electrode formed thereon are opposed to each other between two polarizing plates, and liquid crystal is injected between the substrates to form a liquid crystal layer. The liquid crystal panel adjusts the voltage applied to the transparent electrode provided in the liquid crystal layer for each pixel to thereby adjust the degree of polarization of light from the backlight device passing through the first polarizing plate. Controlling the amount of light passing through the second polarizer,
The image is being displayed. Further, for one of the substrates located between the polarizers, a color display is possible by providing a red (R), green (G), and blue (B) color filter for each pixel.

On the other hand, the backlight device includes, for example, a flat light guide plate and a fluorescent lamp that irradiates the light guide plate with light from an end face. Various configurations have been proposed for the fluorescent lamp used in the backlight device in order to obtain high color rendering properties. In general, a fluorescent film is formed by mixing rare earth phosphors that emit blue, green, and red light. Since the three-wavelength-band emission fluorescent lamp that can obtain various emission spectra depending on the mixing ratio of the phosphor has been put to practical use, the three-wavelength-band emission fluorescent lamp has high luminous efficiency and high color rendering properties. Are widely used as backlight devices for color liquid crystal display devices.

In addition, a pigment dispersion type color filter having excellent durability has been used for a color filter of a liquid crystal panel, and a color liquid crystal display device is used for a liquid crystal color television, a car navigation system, or a liquid crystal display device. It has formed a large market for integrated notebook computers. Further, in recent years, liquid crystal display devices have been
Taking advantage of the features of energy saving and space saving, it has begun to spread as a monitor for a desktop personal computer, and has attracted attention as a display device replacing a conventional CRT monitor.

[0005]

However, at present, the various display performances of the CRT monitor are higher than the various display performances of the liquid crystal display device, and in particular, the so-called EBU (European Broadcast
(ng Union: European Broadcasting Union) No liquid crystal display device meeting the standard has emerged, and achieving this standard is one key to the widespread use of liquid crystal display devices in the field of television or multimedia display devices. Has become. In other words, in the color television system, the shape, movement, and hue of the subject are reproduced on the receiver through the processes of (1) image reception (color camera), (2) transmission, and (3) image reception (receiver). The transmission method of the image signal including the hue is standardized. And as the standard of this transmission system, the United States,
NTSC adopted and broadcast by Canada, Japan, etc.
For the (National Television System Committee) standard, although the chromaticity can be satisfied with the configuration of the conventional liquid crystal display device, the EBU standard that defines the system and standard requires higher color purity, and Higher color purity than the color filter color filters of LCD panels is required.
In particular, since the y value of the blue filter is specified to be small,
It is becoming difficult to meet the standards. In this regard, to increase the color purity, it is conceivable to increase the film thickness of the color filter.However, if the film thickness of the color filter is increased to increase the color purity, the film thickness of only the blue filter increases and the lightness decreases It has the problem of becoming smaller.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fluorescent lamp, a backlight device, and a liquid crystal display device in which the characteristics of the liquid crystal display device satisfy the EBU standard.

[0007]

According to a first aspect of the present invention, there is provided a fluorescent lamp comprising: a bulb; mercury and a rare gas sealed in the bulb; a red phosphor, a green phosphor, and a half bandwidth provided on the inner surface of the bulb. A three-wavelength phosphor layer having a blue phosphor having a wavelength of 40 nm or less;
The deviation is set to not less than 00K and not more than 0.015.

In this configuration, when the fluorescent lamp is used as illumination of a liquid crystal panel provided with a color filter having predetermined transmission characteristics of red, green, and blue via a backlight device, a blue color is obtained. The characteristics and the brightness can be easily improved, and the brightness and the color characteristics of the EBU standard can be simultaneously satisfied for the liquid crystal display device.

That is, while studying a color filter for a liquid crystal panel, a composition of a color filter material having a hue satisfying the EBU standard was discovered. Therefore, the transmission characteristics of blue light are slightly small, and it is necessary to optimize the light source to effectively utilize the characteristics of the color filter material.

According to a second aspect of the present invention, there is provided a backlight device including the fluorescent lamp according to the first aspect, wherein the color temperature of emitted light is set to 7 or less.
000K or more and the deviation is 0.01 or less.

In this configuration, when the emitted light is incident on a liquid crystal panel having red, green, and blue color filters, the blue color characteristics and brightness can be easily improved. And the color characteristics of the EBU standard can be satisfied at the same time.

A liquid crystal display device according to a third aspect of the present invention includes a liquid crystal panel having red, green, and blue color filters;
And a backlight device according to claim 2 for illuminating the liquid crystal panel.

In this configuration, the brightness and the color of the EBU standard are obtained by combining a liquid crystal panel having red, green, and blue color filters having predetermined transmission characteristics with the backlight device according to claim 2. A liquid crystal display device that satisfies the characteristics at the same time is provided.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a fluorescent lamp and a liquid crystal display of the present invention will be described below with reference to the drawings.

FIG. 1 is an exploded perspective view showing one embodiment of a fluorescent lamp, a backlight device, and a liquid crystal display device of the present invention. FIG. 2 is a sectional view of a part of a liquid crystal panel constituting the liquid crystal display device. FIG. 3 is a graph showing transmission characteristics of a color filter of the liquid crystal panel. FIG. 4 is a sectional view in which a part of the fluorescent lamp is omitted. FIG. 5 is an enlarged sectional view of part A of FIG. 4 of the fluorescent lamp. FIG.
3 is a graph showing a spectral distribution of light emitted from the fluorescent lamp. FIG. 7 is a graph showing a spectral distribution of light emitted from the backlight device. FIG. 8 is a sectional view showing another embodiment of the fluorescent lamp, the backlight device, and the liquid crystal display device of the present invention.

In FIG. 1, reference numeral 11 denotes a liquid crystal display device. The liquid crystal display device 11 is also called a color liquid crystal display, and includes a flat liquid crystal panel 12 which is a flat display device as a display means, and a liquid crystal panel 12. And a backlight device 14 for illuminating the backlight from behind.

As shown in FIGS. 1 and 2, the liquid crystal panel 12 has a flat main body portion 15 for displaying images. The main body portion 15 is provided between two polarizing plates 16 and 17. Array substrate 21 which is a glass plate on which transparent electrodes 21a and 22a are formed, respectively.
And a color filter substrate 22 are arranged facing each other, and a liquid crystal is injected between the substrates 21 and 22 to form a liquid crystal layer 24. Further, on the color filter substrate 22, red (R), green (G), and blue (B) color filters CF are formed corresponding to the respective pixels. Also, on the front side of the main body 15,
A protective glass 26 is provided. Further, on the outer peripheral portion of the main body portion 15, a frame portion 27 where a drive circuit and the like are arranged as necessary is provided.
Are attached, and the liquid crystal panel 12 is configured.

The liquid crystal panel 12 adjusts the voltage applied to the transparent electrodes 21a and 22a provided in the liquid crystal layer 24 for each pixel so that the back light passing through the first polarizing plate 16 is adjusted. The degree of polarization of the light from the light device 14 is controlled to control the amount of light passing through the second polarizing plate 17 via each color filter CF, thereby enabling color display of an image.

Here, the color filter CF is a so-called color filter conforming to the EBU standard, formed by using a color filter material having a hue satisfying the EBU standard, which was discovered by examining the composition. As shown in the graph, in this color filter material, the transmission characteristics of blue (B) are slightly smaller than the transmission characteristics of red (R) and green (G), so that the characteristics of this color filter material can be effectively utilized. It was necessary to optimize the light source.

The backlight unit 14 is also called a backlight, a backlight unit, or a cold cathode fluorescent lamp unit. As shown in FIG. 1, the backlight unit 14 is disposed on the back side of the liquid crystal panel 12 and is made of acrylic or the like. A flat light guide plate 31, which is a light guide, a reflection sheet 32 disposed along the back side of the light guide plate 31, a light diffusion sheet 33 disposed along the front side of the light guide plate 31, A fluorescent lamp disposed along the end face of the light plate 31; a reflector 34 for covering the fluorescent lamp FL with the light guide plate 31 side as an irradiation opening; and further, these members are housed in a case 36 having an open front side. It is configured.

The fluorescent lamp FL is, as shown in FIGS. 1, 4 and 5, a cold-cathode fluorescent lamp which is lit at a high frequency, and is sealed at both ends of an elongated cylindrical glass bulb 41. Stop portions 42, 42 are provided, and the sealing portions 42, 42
, The inside of the valve 41 is hermetically sealed, and a rare gas and mercury are sealed therein. Further, a phosphor is applied to the inner wall, that is, the inner surface of the bulb 41, and a phosphor layer 46 is formed.

The inner diameter of the bulb 41 of the fluorescent lamp FL, that is, the inner diameter thereof, depends on the thickness of the light guide plate 31 and the like, but is preferably 5 mm or less, and in the present embodiment, the inner diameter is 3 mm. Have been. Also, this valve 41
Are bent in a substantially L-shape along two continuous sides of the light guide plate 31.

Further, the phosphor layer 46 is of a so-called three-wavelength type, that is, a three-wavelength emission type, and is formed by mixing a red phosphor, a green phosphor, and a blue phosphor of rare earth phosphors at a predetermined mixing ratio. ing. In this embodiment, the red phosphor is europium-activated yttria phosphor (Y ₂ O ₃ : Eu), the green phosphor is cerium,
Terbium co-activated lanthanum phosphate phosphor (LaP
As the O ₄ : Ce, Tb) blue phosphor, a europium-activated strontium calcium barium phosphate phosphor ((Sr, Ca, B) called an apatite phosphor is used.
a) ₅ (PO ₄ ) ₃ Cl: Eu) is used at a predetermined mixing ratio. In this embodiment, the red phosphor is 3
7% by mass, 27% by mass of green phosphor, 36% of blue phosphor
% By mass.

The fluorescent lamp FL is connected to a lamp current
(IL) When the lamp is turned on at 6 mA, the energy distribution of the light L1 emitted from the fluorescent lamp FL, that is, the spectral distribution is as shown in the graph of FIG. 6, and the chromaticity is x = 0.2884, y
= 0.2733, the deviation (duv) is -0.013, the color temperature has become 10000K, the tube surface luminance 31572cd / m ^2. In the graph of FIG. 6, R indicates the peak of the red phosphor, G indicates the peak of the green phosphor, B indicates the peak of the blue phosphor (about 453 nm), and Hg indicates the peak of mercury. . Although not shown, the half width of the blue phosphor is 40 nm or less.

Further, the light emitted from the fluorescent lamp FL
In a state in which L1 is light L2 that passes through the light guide plate 31 and the like and is emitted from the backlight device 14, that is, light that enters the liquid crystal panel 12, the energy distribution, that is, the spectral distribution is
And the chromaticity is x = 0.307
6, y = 0.2970, deviation (duv) is -0.01
1. The color temperature is 7212K, the average luminance of the unit plate surface is 42.
It is 80 cd / m ² . In the graph of FIG. 6, R represents the peak of the red phosphor, G represents the peak of the green phosphor, B represents the peak of the blue phosphor, and Hg represents the peak of mercury.

In the liquid crystal display device 11 in which the backlight device 14 and the liquid crystal panel 12 having the optical color filter CF are combined, the emission spectrum characteristics of the backlight device 14 as a light source, in particular, the color temperature and The configuration and the manufacturing method of matching the deviation and the transmission spectrum characteristic of the color filter CF composed of three colors of RGB in a specific range realizes higher saturation than before, and particularly improves the blue saturation and adds the RGB. The liquid crystal display device 11 which satisfies the EBU standard with respect to the chromaticity of the three primary colors of the image receiving device, ie, the three primary colors of the image receiving device, which determines the reproduced colors of the color television that performs color reproduction by color mixture can be provided.

The three primary colors of the EBU standard are as follows: red (R): x = 0.64, y = 0.33 green (G): x = 0.29, y = 0.60 blue (B): x = 0.15, y = 0.06, and are defined as the three primary colors of image reception in the NTSC system. Red (R): x = 0.67, y = 0.33 Green (G): x = 0.21 y = 0.71 Blue (B): x = 0.14, y = 0.08 On the other hand, the color purity of red (R) and green (G) is set low, so that the current This can be achieved by a color filter using a pigment-dispersed material and a conventional fluorescent lamp. On the other hand, with respect to the blue (B) EBU standard, the current color filter using copper phthalocyanine has a film thickness of 8 when combined with a conventional fluorescent lamp.
μm, and the current color filters are 1-2
Considering μm, the reality was difficult in terms of brightness and the like.

In this regard, according to the present embodiment, with respect to the fluorescent material of the fluorescent lamp FL, the light emitted from the blue fluorescent material having a half width of 40 nm or less is used together with the red fluorescent material and the green fluorescent material at a predetermined ratio. Since L1 has a color temperature of 8500K or more, more preferably 9000K or more, and a deviation of 0.015 or less, more preferably 0.005 or less, the light L2 emitted from the backlight device 14 has a color temperature of 7000K or more.
More preferably, the deviation can be made 7500K or more and the deviation can be made 0.01 or less. As a result, the liquid crystal display device 11 conforming to the EBU standard can be effectively used by effectively utilizing the characteristics of the color filter having the hue suitable for the EBU standard. Could be provided.

In the above-described embodiment, the backlight device 14 is a so-called sidelight type in which the fluorescent lamps FL are arranged along the end surface of the light guide plate 31, but the present invention is not limited to this configuration. As shown in FIG. 8, the light guide plate is not used, and a substantially U
A fluorescent lamp FL bent in a letter shape or the like can be arranged, and the electrode is not limited to a cold cathode, and may be a fluorescent lamp having a hot cathode.

Hereinafter, in the configuration shown in FIG.
m, the mixture ratio of the red phosphor, green phosphor, and blue phosphor of the rare earth phosphor applied to the inner surface of the bulb 41 having a tube length of 173 mm is changed, and the red, green, The experimental result which evaluated the color reproducibility of blue is shown. That is, as a result of this experiment, the color temperature was low,
Moreover, when the deviation was low, the fluorescence was poor in color characteristics and low in brightness. In particular, the color characteristics vary depending on the characteristics of the blue phosphor, and a europium-activated barium magnesium aluminate phosphor (BaMg ₂ Al ₁₆ O ₂₇ : E) which is generally known as a BAM phosphor and has a wide half width.
u) tended to have poor color characteristics.

For this reason, the blue phosphor is a europium-activated strontium-calcium-barium phosphate phosphor ((Sr, Ca, Ba) ₅ ) called an apatite phosphor.
(PO ₄ ) ₃ Cl: Eu)) was used, and the chromaticity was variously changed. As a result, the results shown in Table 1 were obtained.

[0032]

[Table 1] In the experiment, the lamp current was adjusted to 6 mA, and the lamp was turned on at a high frequency of 2.2 W and a frequency of 33 kHz. Chromaticity is measured by MSR-7 manufactured by Opt Research Co., Ltd.
000 and the brightness is BM-7 manufactured by Topcon Co., Ltd.
Measured using

The backlight device uses a sidelight type backlight, and the light guide plate has a long side of 81 mm and a short side of 6 mm.
A 1 mm rectangular, 4 mm thick acrylic plate is used as the light diffusion sheet, and a light diffusion sheet (model name D115
Or D121), and a reflection sheet of model name E60L manufactured by Toray Industries, Inc. was used.

From the experimental results, the fluorescent lamp FL
It was found that good color characteristics can be realized in a state where the color temperature is 8500K or more and the deviation is 0.015 or less.

In an actual use state, the light source for irradiating the color filter CF with light is used in a united backlight device 14 as shown in FIG. The chromaticity and deviation of the light device (backlight unit) 14 are also shown in Table 1.

[0036]

According to the first aspect of the present invention, the fluorescent lamp is illuminated, via the backlight device, with a liquid crystal panel having red, green, and blue color filters having predetermined transmission characteristics. When used as, the color characteristics and the brightness of blue can be easily improved, and the brightness and the color characteristics of the EBU standard can be simultaneously satisfied for the liquid crystal display device.

According to a second aspect of the present invention, the backlight device includes the fluorescent lamp according to the first aspect, wherein the emitted light has a color temperature of 7000 K or more and a deviation of 0.01 or less. When the light is incident on a liquid crystal panel having green and blue color filters, the color characteristics of blue and the brightness can be easily improved, and the liquid crystal display device can simultaneously satisfy the brightness and the color characteristics of the EBU standard.

According to the liquid crystal display device of the third aspect, since the liquid crystal display device includes: a liquid crystal panel having red, green, and blue color filters; and the backlight device of the second aspect for illuminating the liquid crystal panel. A liquid crystal display device that satisfies both brightness and EBU standard color characteristics simultaneously by combining a liquid crystal panel having red, green, and blue color filters having predetermined transmission characteristics with the backlight device according to claim 2. Can be provided.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing one embodiment of a fluorescent lamp, a backlight device, and a liquid crystal display device of the present invention.

FIG. 2 is a cross-sectional view of a part of a liquid crystal panel included in the liquid crystal display device.

FIG. 3 is a graph showing transmission characteristics of a color filter of the liquid crystal panel.

FIG. 4 is a sectional view in which a part of the fluorescent lamp is omitted.

FIG. 5 is an enlarged sectional view of a portion A of FIG. 4 of the fluorescent lamp.

FIG. 6 is a graph showing a spectral distribution of light emitted from the fluorescent lamp.

FIG. 7 is a graph showing a spectral distribution of light emitted from the backlight device.

FIG. 8 is a sectional view showing another embodiment of the fluorescent lamp, the backlight device, and the liquid crystal display device of the present invention.

[Explanation of symbols]

 11 LCD device 12 LCD panel 14 Backlight device 41 Bulb 46 Phosphor layer CF Color filter FL Fluorescent lamp

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takao Taguchi 1-5-1, Taito, Taito-ku, Tokyo Inside Toppan Printing Co., Ltd. (72) Inventor Eriko Nagata 1-1-5-1 Taito, Taito-ku, Tokyo Letterpress Inside Printing Co., Ltd. (72) Inventor Yoshitomi Dobashi 4-3-1 Higashishinagawa, Shinagawa-ku, Tokyo Toshiba Lighting & Technology Corporation (72) Inventor Yuji Agatsuma 4-3-1 Higashishinagawa, Shinagawa-ku, Tokyo Toshiba Lighting & Technology F term (for reference) 2H091 FA02Y FA42Z LA15 LA30 5C043 AA01 AA20 BB04 CC09 CD01 DD39 EB02 EC20 5G435 AA00 BB12 EE27 FF03 FF06 FF08 GG12 GG24 HH00 LL03

Claims (3)

[Claims] A bulb; a mercury and a rare gas sealed in the bulb; a red phosphor, a green phosphor, and a blue phosphor having a half width of 40 nm or less provided on the inner surface of the bulb.
A wavelength-type phosphor layer, the color temperature of the emitted light is 8500K or more, and the deviation is 0.01
A fluorescent lamp characterized in that the number is 5 or less. 2. A backlight device comprising the fluorescent lamp according to claim 1, wherein the emitted light has a color temperature of 7000 K or more and a deviation of 0.01 or less. 3. A liquid crystal panel having red, green, and blue color filters; and illuminating the liquid crystal panel.
A liquid crystal display device comprising: the backlight device according to any one of the preceding claims.