JP2002313282A - White color light source and color display device using the white color light source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize high luminance, without increasing the lamp power by mixing a fluorescent substance having different afterglow time, in fluorescent substance of red color emission and/or green color emission. SOLUTION: The white color light source, which is incorporated in the color display device and has formed on the inner face of the bulb the fluorescent substance membrane, using a fluorescent substance that has an emission peak in at least three wavelength regions of red, green and blue bases, is constructed of a fluorescent substance membrane, that contains a fluorescent substance having an afterglow time of 2 ms or shorter and a fluorescent substance having an afterglow time of 8 ms or shorter. The fluorescent substance, having an afterglow time of 8 ms or shorter, has an emission quantity of 110% or more than the fluorescent substance having an afterglow time of 2 ms or less, and the peak wavelength of the red color is set at 600-660 nm, and the peak wavelength of the green color is set at 480-560 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a white light source of, for example, a field sequential color display device and a holding type display device, and more particularly to a white light source which is incorporated in a color display device to improve luminance and uses the white light source. The present invention relates to a color display device.

[0002]

2. Description of the Related Art Conventionally, a field sequential type color display device has three backlights of red, green and blue.
A white light source such as a three-wavelength fluorescent lamp having an emission peak in the wavelength region is used, and the white light from the lamp is switched to red, green, and blue light by means such as a polarizing plate and sequentially emitted to the display screen. Due to the afterglow phenomenon in the retina of a person, the continuous surface images of red, green and blue are superimposed on the naked eye to make them feel as a group of full-color images (for example, JP-A-7-13149, JP-A-10-
No. 28275) and a transmissive type in which a backlight of red light emission, green light emission, and blue light emission is sequentially blinked at a high speed of 1/180 second, and a monochrome image is displayed on a liquid crystal in response to this (for example, JP-A-1-179914, JP-A-9-324386, JP-A-11-16
No. 0675, JP-A-2000-147548,
Japanese Patent Application Laid-Open No. 2000-111910).

In the field sequential type color display device, the former white light source has a plurality of emission colors of red, green and blue on the inner surface of the bulb so as to have emission peaks in three wavelength ranges of red, green and blue. Fluorescent lamps and CRTs configured to obtain white light emission by forming a phosphor coating formed by mixing the above phosphors are used. Also, one field of 60 Hz is set, and the color of light transmitted through the color filter is switched in the order of red, green, and blue within 16.7 ms of one field, so that 16.7 ms of one field is obtained from the color display device.
The red, green, and blue color images must be sequentially emitted, and if the afterglow time is too long for each color, the color purity of each of the red, green, and blue colors cannot be obtained. Light time 3ms
Less phosphors were used. Specifically, the phosphor emitting red light _{Y 2 O 2 S: Eu (} : _is, E to Y 2 _{O 2} S
u means that this emits light. The same applies hereinafter. ) Or YV ₄ : Eu, and BaMgAl ₁₀ O ₁₇ : Eu or (Sr, Ca, B
a) ₅ (PO ₄ ) ₃ Cl ₂ : Eu was used, and SrAl ₂ O ₄ : Eu was used as a green light emitting phosphor. YV
O ₄ : Eu 30.3% by weight, SrAl ₂ O ₄ : Eu 26.3% by weight, BaMgAl ₁₆ O ₂₇ : Eu 4
A fluorescent lamp having a phosphor coating having a phosphor coating mixed with 3.4% by weight was incorporated in the same manner as in FIG. 2 to form a backlight device, thereby producing a field-sequential color liquid crystal display device which was immediately known. FIG. 5 shows the emission spectrum of a lamp incorporated in a backlight, and FIG. 6 shows the results. FIG. 6 shows the emission spectrum of the above-described conventional fluorescent lamp which has passed through a color filter of a color liquid crystal display device. FIG. This LCD screen has a luminance of 80
cd / m ² .

The light source of the latter transmissive liquid crystal display device has a structure in which a single color cap of red, green and blue is attached to a lamp, or a light emitting diode of three colors of red, green and blue blinks at high speed. Therefore, the type of the phosphor was not limited.

[0005]

However, the phosphor used in the above-mentioned conventional white light source has a luminous efficiency of 5 times as long as the long afterglow phosphor used in the fluorescent lamp for general illumination.
It is as low as about 0%. To increase the brightness of the screen of the color display device, it is conceivable to increase the lamp current. However, when the lamp current is increased, the consumption of mercury is remarkable and the life of the color display device is shortened. there were. The present invention has been made to solve the above problems,
It is an object of the present invention to provide a white light source that improves the luminance of a mixed phosphor to improve luminance with the same lamp power, and a color display device incorporating the white light source.

[0006]

According to a first aspect of the present invention, there is provided a light transmitting function for transmitting any one of red, green, and blue light, provided for each pixel. And a light source incorporated in a color display device having a light shutter function of switching or controlling transmitted light, wherein the phosphor uses a phosphor having emission peaks in at least three wavelength ranges of red, green and blue. In a white light source in which a coating is formed on the inner surface of a bulb, the phosphor coating includes a phosphor having an afterglow time of 2 ms or less and a phosphor having an afterglow time of 8 ms or less, and the afterglow time is 8 ms or less. Are phosphors having a persistence time of 2 ms or less.
% Or more and the red peak wavelength is 600
660 nm, and the green peak wavelength is 480-56.
It is characterized by being set to 0 nm. In the invention according to claim 2, the phosphor coating having emission peaks in at least three wavelength ranges of red, green, and blue is a phosphor that emits red light and has a persistence time of 8 ms or less. It is a europium-activated red phosphor. In the invention according to claim 3, the phosphor coating having emission peaks in at least three wavelength ranges of red, green, and blue is a phosphor that emits green light and has a persistence time of 8 ms or less, It is a cerium-terbium-activated green phosphor. According to a fourth aspect of the present invention, the phosphor coating having emission peaks in at least three wavelength ranges of red, green and blue is that the phosphor emitting blue light is a europium-activated blue phosphor. Features. In the invention according to claim 5, the phosphor that emits reddish light is any one of Y ₂ O ₃ : Eu or Y ₂ O ₂ S: Eu or YVO ₄ : Eu or Y (PV) O ₄ : Eu. It is characterized by containing more than one species and Y ₂ O ₃ : Eu as a main component. The invention according to claim 6 is characterized in that the phosphor emitting green light is LaPO ₄ : Ce, Tb. According to a seventh aspect of the present invention, there is provided the white light source according to any one of the first to sixth aspects, and the white light source is connected to the white light source in an amount of 30 to 8.
A high-frequency lighting device for lighting at a frequency of 0 KHz, a light transmission function provided for each pixel and transmitting any of red, green, and blue light, and an optical shutter function for switching or controlling transmitted light are provided. It is characterized by the following.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partially cutaway front view of a straight fluorescent lamp used in a color liquid crystal display device as an example of a white light source, and FIG. 2 is an illumination device incorporating a white light source. First, in FIG. 1, the fluorescent lamp 1 seals both ends of a straight tube-shaped glass bulb 2 made of transparent glass, seals a pair of internal electrodes 3 inside both ends, and electrically connects these internal electrodes 3 to each other. The connected lead-in wires 4 pass through the sealing portions at both ends in an airtight manner and are led out. A discharge medium that generates ultraviolet rays by discharge is sealed inside the glass bulb 2, and a phosphor coating 5 that emits white light by ultraviolet rays is formed on the inner surface of the glass bulb 1.

The phosphor film 5 is formed of a three-wavelength light-emitting phosphor having emission peaks in at least three wavelength regions of red, green and blue. The emission peak is 600 for red.
To 660 nm, and green for 480 to 560 nm. As the three-wavelength light emitting phosphor, a mixture of at least three kinds of phosphors of a red light emitting phosphor, a green light emitting phosphor, and a blue light emitting phosphor is used. The present inventor has focused on the afterglow time, emission peak wavelength, and luminance (emission intensity) of the phosphor, and has identified a phosphor that can achieve higher luminance of the white light source of the present invention. Table 1 below shows a list of the specified phosphors.

[0009]

[Table 1]

As shown in Table 1 above, the phosphor emitting red light is Y ₂ O ₃ : Eu or Y ₂ O ₂ S: Eu or Y
One or more of VO ₄ : Eu or Y (PV) O ₄ : Eu and Y ₂ O ₃ : Eu are used, and SrAl ₂ O ₄ : Eu and LaPO ₄ : Ce, T are used as green light emitting phosphors.
b, and the phosphor emitting blue light is BaMgAl ₁₀
O ₁₇ : Eu or (Sr, Ca, Ba) ₅ (PO ₄ ) ₃ C
l ₂ : Eu is used.

As a white light source, YVO is used as a red light emitting phosphor.
₄ : 30% by weight of Eu, SrAl _{2 as} green light emitting phosphor
13.4% by weight of O ₄ : Eu, LaPO ₄ : Ce, T
b at 13.15% by weight, and a blue-emitting phosphor of BaMgA
A fluorescent lamp 1 that emits white light using a phosphor mixed with 43.4% by weight of l ₁₀ O ₁₇ : Eu as a phosphor coating 5.
It was created. Then, as shown in FIG. 2, the fluorescent lamp 1 is provided on the secondary side of the pulse transformer 6, and the signal output terminal 7 is connected to the base of the switching element so that a rectangular wave signal voltage can be applied. A lighting device (backlight device) was created. The emission spectrum of the fluorescent lamp 1 was measured, and the result is shown in FIG.

Next, this illuminating device was provided on the back surface of a known color filter or an RGB switching panel to produce a known field sequential type color liquid crystal display device. The emission spectrum of the fluorescent lamp according to the present embodiment that passed through the color filters of the color liquid crystal display device was measured, and the results are shown in FIG. The screen of the color liquid crystal display had a luminance of 100 cd / m ² . Also, as compared with FIG. 6, it can be seen that the amount of light is increased by about 25% and the luminance is improved.

Next, a second embodiment will be described. As a white light source, YVO ₄ : E
u, 15% by weight of Y ₂ O ₃ : Eu, 13.15% by weight of SrAl ₂ O ₄ : Eu as a phosphor emitting green light, 13.15% by weight of LaPo ₄ : Ce, Tb, blue 43. BaMgAl ₁₀ O ₁₇ : Eu as a light emitting phosphor.
A fluorescent lamp mixed with 4% by weight of the phosphor was formed on the inner surface of the bulb and incorporated in a field-sequential color liquid crystal display device using a fluorescent lamp as a backlight. The emission spectrum of the fluorescent lamp passing through the color filter is as shown in FIG. Compared to the conventional example of FIG. 5, the phosphor emitting red light emits 50% by weight of a phosphor having an afterglow time of 2 ms or less and Y _2.
When a mixture of O ₃ : Eu of 50% by weight is used, the light amount is increased by about 35%. In the afterglow characteristic, as shown by the solid line in FIG. 8, the afterglow component remains, but since the amount of light is increased as a whole, it cannot be visually recognized by the naked eye and does not pose a problem.

[0014]

As described above, by mixing phosphors having different afterglow times with the phosphors emitting red and / or green light, it is possible to increase the luminance without increasing the lamp power. When the luminance is set to be the same as that of a white light source using only the afterglow phosphor, power consumption can be reduced and the life can be extended.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view of a fluorescent lamp as an example of a white light source.

FIG. 2 is a circuit diagram showing a lighting device incorporating a fluorescent lamp.

FIG. 3 is an emission spectrum diagram showing an example of a white light source according to the present invention in which two kinds of phosphors emitting green light are mixed.

FIG. 4 is an emission spectrum diagram showing an example of a white light source that has passed through an LCD in the color display device of the present invention.

FIG. 5 is an emission spectrum diagram of a white light source used in a conventional field sequential color display device.

FIG. 6 is an emission spectrum diagram of light transmitted through an LCD in a conventional field sequential type color display device.

FIG. 7 is an emission spectrum diagram of LCD transmitted light using a mixture of two types of phosphors that emit red and green light in the white light source of the present invention.

FIG. 8 is a diagram showing afterglow characteristics.

[Explanation of symbols] 2 bulbs 5 phosphor coating

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09K 11/78 CPW C09K 11/78 CPW CQA CQA 11/81 11/81 11/82 11/82 11/83 11/83 11/84 11/84 G02F 1/1335 G02F 1/1335 G09F 9/00 336 G09F 9/00 336F 337 337Z F term (reference) 2H091 FA37 FB02 FB12 FB13 LA03 4H001 CA01 CA05 CA07 XA08 XA15 XA16 XA39 XA39 XA39 XA39 YA58 YA63 YA65 5C043 AA02 BB04 CC09 CD01 DD28 EB02 EB04 EC14 EC16 EC17 EC18 5G435 AA03 AA04 AA14 BB12 BB15 CC12 GG24 GG27 HH06

Claims (7)

[Claims] 1. A white color incorporated in a color display device provided for each pixel and having a light transmission function of transmitting any one of red, green, and blue light, and an optical shutter function of switching or controlling transmitted light. In a white light source, wherein a phosphor film using a phosphor having emission peaks in at least three wavelength ranges of red, green and blue is formed on the inner surface of the bulb, the phosphor film has an afterglow time of 2 ms. The following phosphor and a phosphor having an afterglow time of 8 ms or less are included, and the phosphor having an afterglow time of 8 ms or less emits light of 110% or more of the phosphor having an afterglow time of 2 ms or less. And a red peak wavelength of 600 to 660 nm and a green peak wavelength of 480 to 560 nm. 2. The phosphor coating having emission peaks in at least three wavelength ranges of red, green and blue is a phosphor emitting red light and having an afterglow time of 8 ms or less. The white light source according to claim 1, wherein the white light source is a red phosphor. 3. The phosphor film having emission peaks in at least three wavelength ranges of red, green and blue, wherein the phosphor which emits green light and whose afterglow time is 8 ms or less is cerium terbium. 3. The white light source according to claim 1, wherein the white light source is an activated green phosphor. 4. The phosphor coating having emission peaks in at least three wavelength ranges of red, green and blue, wherein the phosphor emitting blue light is a europium-activated blue phosphor. The white light source according to claim 1, 2 or 3. 5. The phosphor that emits red light is Y ₂ O.
₂ : Eu or Y ₂ O ₂ S: Eu or YVO ₄ : Eu
5. The white light source according to claim 1, wherein at least one of Y (PV) O ₄ : Eu and Y ₂ O ₃ : Eu are used as main components. 6. 6. The phosphor that emits green light is LaP
O ₄ : Ce, Tb, wherein:
The white light source according to 2, 3, 4 or 5. 7. The white light source according to claim 1, a high-frequency lighting device for lighting the white light source at a frequency of 30 to 80 KHz, and a red light source provided for each pixel.
A light transmission function of transmitting any of green or blue light,
A color display device having an optical shutter function for switching or controlling transmitted light.