JP2008111035A - Phosphor, light source equipment and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phosphor having improved emission intensity and to provide light source equipment and a display device having the phosphor. <P>SOLUTION: The phosphor comprises Eu, one or more A elements selected from the group consisting of bivalent metal elements such as Ca, one or more B elements selected from the group consisting of tetravalent metal elements such as Si, one or more E elements selected from the group consisting of trivalent metal elements such as Al and one or more elements selected from the group consisting of N, C and O. The phosphor is composed so that the Eu is contained in an amount of ≥2.0 to ≤5.0 mol%. The phosphor has the luminescence center wavelength between 650 and 670 nm and is used in the light source equipment and the display device. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a phosphor, a light source device including the phosphor, and a display device including the light source device.

In a display device called a so-called flat panel display such as a liquid crystal display, an optical element (such as a liquid crystal element) that contributes to light output is not a self-luminous element but a passive type that modulates light applied from the outside. Since it is an element, a light source device serving as a backlight is provided separately from the optical element.
In general, there are two types of backlights, a direct light method and an edge light (side light) method.

As this backlight, a structure using a cold cathode tube has been generally used. However, in recent years, light emitting diodes (LEDs) with high luminous efficiency have been developed, and research on using them as light sources for backlights is underway.
As a known LED light source of a backlight, phosphors (yellow phosphors) that convert yellow light are dispersed around a blue light emitting LED, and white is obtained by combining blue and yellow so-called white. LED is mentioned. Also, there is a method of obtaining white light by a configuration in which yellow phosphors are dispersed in a light guide plate, a reflection sheet, an optical film, etc., and blue light of a blue LED is irradiated to these yellow phosphors at remote positions. It has been proposed (see, for example, Patent Document 1).

In addition, in the configuration in which the visible light region other than the blue region is covered with yellow, it is difficult to obtain desired characteristics particularly in display applications where demands for each color of red (R), green (G), and blue (B) are severe. . The characteristic here is luminance and chromaticity in each color of RGB.
On the other hand, a phosphor that converts blue light into green light (green phosphor) and a phosphor that converts blue light or green light into red light (red phosphor) according to demands in display applications. There has also been proposed a method for making them closer to desired characteristics by selecting each of them (see, for example, Patent Document 2).

Conventionally, for simple lighting applications, for example, the emission spectrum of a phosphor only needs to be continuous over a wide range, so that the emission intensity at a specific wavelength is not necessarily a problem. It was.
However, in the display, for example, if the boundary between red light and green light is ambiguous, it is difficult to express the target color because the colors of the red and green pixels that should be independent of each other are mixed. Will go down. Therefore, in a display, in order to obtain appropriate color expression and sufficient light emission intensity, it is necessary to selectively improve the light emission intensity at a specific wavelength.

Conventionally, since the light emission of the phosphor has been studied with a simple lighting application in mind, the element that becomes the emission center of the phosphor (for example, Eu) is 0.8 mol to 1.6% in the phosphor crystal. It was thought that it was contained by the ratio (for example, refer nonpatent literature 1).
However, as described above, in the display, since the requirement for the phosphor is special, it has been required to study a more appropriate composition.
Japanese Patent Laid-Open No. 08-007614 JP 2004-327492 A Proceedings of the 305th Society of Phosphors, Yuta Ueda et al., Pp. 37-47

  The present invention has been made in view of such problems, and an object of the present invention is to provide a phosphor with improved emission intensity, and a light source device and a display device having the phosphor. .

The phosphor according to the present invention is a phosphor containing at least Eu, an A element, a D element, an E element, and an X element, and the Eu is 2.0 mol% or more and 5.0 mol% or less. It is characterized by being included in the ratio.
A is one or more elements selected from the group consisting of divalent metal elements, D is one or more elements selected from the group consisting of tetravalent metal elements, and E is One or more elements selected from the group consisting of trivalent metal elements, X is one or more elements selected from the group consisting of N, C, and O.

The light source device according to the present invention is a light source device having a phosphor, wherein the phosphor includes at least Eu, an A element, a D element, an E element, and an X element, and the Eu is It is contained at a ratio of 2.0 mol% or more and 5.0 mol% or less.
A is one or more elements selected from the group consisting of divalent metal elements, D is one or more elements selected from the group consisting of tetravalent metal elements, and E is One or more elements selected from the group consisting of trivalent metal elements, X is one or more elements selected from the group consisting of N, C, and O.

A display device according to the present invention is a display device including a light source device having a phosphor, and the phosphor includes at least Eu, an A element, a D element, an E element, and an X element. The Eu is contained at a ratio of 2.0 mol% or more and 5.0 mol% or less.
A is one or more elements selected from the group consisting of divalent metal elements, D is one or more elements selected from the group consisting of tetravalent metal elements, and E is One or more elements selected from the group consisting of trivalent metal elements, X is one or more elements selected from the group consisting of N, C, and O.

  According to the phosphor according to the present invention, Eu is contained at a ratio of 2.0 mol% or more and 5.0 mol% or less, so that the emission intensity can be improved.

  According to the light source device of the present invention, since Eu is contained in the phosphor at a ratio of 2.0 mol% or more and 5.0 mol% or less, a more excellent light source device can be configured.

  According to the display device according to the present invention, Eu is contained in the phosphor at a ratio of 2.0 mol% or more and 5.0 mol% or less, so that a more excellent display device can be configured.

  An embodiment of the present invention will be described.

<Embodiment of phosphor>
The phosphor according to the present invention is a phosphor containing at least Eu, an A element, a D element, an E element, and an X element, and the Eu is 2.0 mol% or more and 5.0 mol% or less. It is characterized by being included in the ratio.
Here, A is one or more elements selected from the group consisting of divalent metal elements, D is one or more elements selected from the group consisting of tetravalent metal elements, E Is one or more elements selected from the group consisting of trivalent metal elements, and X is one or more elements selected from the group consisting of N, C, and O.

  According to the phosphor according to the present embodiment, since the concentration of Eu contained in the crystal lattice of the phosphor is 2.0 mol% or more and 5.0 mol% or less, as shown in the examples described later, light emission The strength is improved. In particular, when the amount is 2.5 mol% or more and 4.0 mol% or less, the improvement in emission intensity is particularly remarkable.

Here, a specific example of a manufacturing method for obtaining such a phosphor according to the present invention will be described.
In the production of the phosphor in the present embodiment, first, Si ₃ N ₄ , AlN, Ca ₃ N ₂ , and EuN are mixed at a molar ratio of 1: 3: 0.95 to 0.99: 0.03 to 0.03. Mix at a rate of 15.
Then, 10 g is weighed out of this mixture.

Then, it mixes using an agate mortar in the glove box of nitrogen atmosphere, and produces an intermediate body.
The powder obtained by mixing the obtained intermediate was inserted into a cylindrical crucible made of BN. The mixed powder inserted into the crucible is held (baked) at a temperature of 1700 ° C. for 2 hours in a mixed gas atmosphere of nitrogen gas (N ₂ ) and hydrogen gas (H ₂ ) to produce the phosphor according to the present embodiment.

  In this way, the phosphor according to this embodiment is obtained.

<Embodiment of light source device and embodiment of display device>

FIG. 1 shows a schematic configuration diagram of a display device having a light source device according to the present embodiment.
The display device 1 according to this embodiment includes a light source device 2 and an optical device 3.

The light source device 2 according to the present embodiment is a backlight device for the optical device 3 having a liquid crystal device. In the present embodiment, the display device 1 is a direct type.
In the light guide unit 7 made of resin of the light source device 2, for example, a plurality of light emitters 6 are provided on the surface of a blue light source formed of a blue LED. The shape of the light emitter 6 can be appropriately selected from various types such as a side emitter type and a shell type in the case of an LED.

In the fluorescent part 8, the above-described phosphors are dispersedly arranged in a medium made of resin, for example.
Here, the medium in which the phosphor is dispersed may be a resin (a part of the white LED) directly formed around the blue light emitting LED, or a blue light emitting LED such as a light guide plate, a reflection sheet, or an optical film. Even if the medium is located away from the medium, any medium in which the phosphors are dispersedly arranged may be used.

In the present embodiment, the fluorescent part 8 is composed of a first fluorescent part 8a made of a first phosphor and a second fluorescent part 8b made of a second fluorescent substance, which have different emission wavelength bands.
As a 1st fluorescent substance which comprises the 1st fluorescent part 8a, CaS: Eu can be mentioned as a red fluorescent substance, for example. In this case, fluorescence having a spectrum with an emission center wavelength of 654 nm and a main emission wavelength band of 600 nm to 750 nm is obtained based on light irradiation in a wavelength band (excitation wavelength band) corresponding to an excitation spectrum having a peak near 450 nm. Can do. In order to obtain red light emission, the emission wavelength band of the first phosphor preferably includes at least a part of 610 nm to 670 nm.
The second phosphor constituting the second fluorescent unit 8b is, for example as a green phosphor _{(Sr 1-xy Ca x Ba} y) Ga 2 S 4: Eu may be mentioned (0 ≦ x ≦ 1,0 ≦ y ≦ 1, x + y ≦ 1). As an example, when SrGa ₂ S ₄ : Eu is used, a spectrum having an emission center wavelength of 532 nm and a main emission wavelength band of 490 nm to 600 nm is obtained based on light irradiation in a wavelength band corresponding to an excitation spectrum having a peak near 450 nm. The fluorescence which has can be obtained. In order to obtain green light emission, the emission wavelength band of the second phosphor preferably includes at least part of 510 nm to 550 nm.
In the light source device 2 according to this embodiment, at least one of the first phosphor and the second phosphor is the phosphor according to this embodiment described above.

A diffusion sheet 9 is provided at the closest portion of the light source device 2 facing the optical device 3. The diffusion sheet 9 uniformly guides light from the blue light source and each phosphor to the optical device 3 side in a planar shape. A reflector 4 is provided on the back surface side of the light source device 2. Further, if necessary, a reflector 5 similar to the reflector 4 is also provided on the side surface of the light guide unit 7.
As the resin, various transparent resins can be used in addition to epoxy, silicone, and urethane.
In addition, the light source device 2 is good also as a system by which the light-emitting body 6 is arrange | positioned at the side surface of the light guide part 7, as shown in FIG. That is, the light from the light emitter 6 is reflected by the rear slope of the light guide 7 and reaches the diffusion sheet 9 through the first prism sheet 21 and the second prism sheet 22, so-called edge light (side light). It may be a method. In this configuration, the fluorescent part 8 is not shown, but between the light emitter 6 and the light guide part 7, or between the light guide part 7 and the reflectors 4 and 5, or between the light guide part 7 and the first prism sheet. 21 is provided at any position.

On the other hand, in this embodiment, the optical device 3 is a liquid crystal device that outputs predetermined output light by modulating light from the light source device 2.
In this optical device 3, from the side close to the light source device 2, the deflection plate 10, the glass substrate 11 for TFT (Thin Film Transistor) and the dot electrode 12 on the surface thereof, the liquid crystal layer 13 and the front and back thereof. The deposited alignment film 14, the electrode 15, a plurality of black matrices 16 on the electrode 15, and first (red) color filters 17 a and second (green) corresponding to the pixels provided between the black matrices 16. The color filter 17b, the third (blue) color filter 17c, the glass substrate 18 provided separately from the black matrix 16 and the color filters 17a to 17c, and the deflection plate 19 are arranged in this order.
Here, the deflecting plates 10 and 19 form light that vibrates in a specific direction. The TFT glass substrate 11, the dot electrode 12, and the electrode 15 are provided for switching the liquid crystal layer 13 that transmits only light oscillating in a specific direction, and the alignment film 14 is also provided. Thus, the inclination of the liquid crystal molecules in the liquid crystal layer 13 is aligned in a certain direction. Further, since the black matrix 16 is provided, the contrast of light output from the color filters 17a to 17c corresponding to the respective colors is improved. The black matrix 16 and the color filters 17 a and 17 c are attached to the glass substrate 18.

  According to the light source device and the display device according to the present embodiment, in the fluorescent part 8 in the light source device 2, at least one of the first phosphor and the second phosphor is a concentration of Eu contained in the crystal lattice of the phosphor. Is selected from 2.0 mol% to 5.0 mol%, the emission intensity can be improved as will be described later.

  <Example>

Examples of the present invention will be described.
In this example, a result of specifically examining the obtained phosphor by manufacturing the phosphor by the above-described manufacturing method will be described.

FIG. 3 shows the results of examining the change in emission intensity according to the change in the Eu concentration (mol%) in the phosphor according to the present example.
Luminescence intensity was measured using a spectrophotometer (SPLU FLUOROLOG-3). Using this spectrophotometer, each phosphor was irradiated with blue light having an emission center wavelength of 460 nm, and an emission spectrum generated from the phosphor by excitation of the blue light was measured in a range of 500 nm to 780 nm.

  From the results of FIG. 3, it was confirmed that high emission intensity was obtained when Eu was 2.0 mol% or more. In addition, it was confirmed that particularly high emission intensity was obtained in the range included at a ratio of 2.5 mol% to 4.0 mol%. In this range, particularly high emission intensity is obtained even compared to the average value (curve x in the figure).

FIG. 4 shows the results of examining the change in the emission center wavelength according to the change in the Eu concentration (mol%) in the phosphor according to this example.
From the result of FIG. 4, it was confirmed that the wavelength was increased with the Eu concentration. In this range, the wavelength has been greatly increased even in comparison with the average value (straight line y in the figure).

From the above results, according to the phosphor according to the present example, in the range where Eu concentration is 2.0 mol% or more and 5.0 mol% or less, improvement in emission intensity and increase in emission center wavelength are achieved. It is done.
Although not shown, it was confirmed that the luminance of the sample having the Eu concentration of 5.0 mol% was 20% or more lower than that of the sample of 1.0 to 4.0 mol%. Therefore, it is considered that particularly high luminance can be achieved at 2.5 mol% or more and 4.0 mol% or less.

  As described in the above embodiment, according to the phosphor, the light source device, and the display device according to the present embodiment, the concentration of Eu contained in the crystal lattice of the phosphor is 2.0 mol% or more and 5. Since it is 0 mol% or less, the emission intensity can be improved.

  In particular, according to the phosphor according to the present embodiment, it is possible to ensure and select the wavelength band by shortening the wavelength or increasing the wavelength as necessary. As a specific example, it is possible to increase the wavelength of a red phosphor. According to the increased wavelength of red, it is possible to suppress mixing with green and causing noise to each other. Therefore, according to the phosphor according to the present embodiment, the characteristics of the light source device and the display device can be made more desirable.

  Note that the numerical conditions such as the materials used, the amount thereof, the processing time, and the dimensions mentioned in the description of the above embodiments are only suitable examples, and the dimensions, shapes, and arrangement relationships in the drawings used for the description are also schematic. Is. That is, the present invention is not limited to this embodiment.

  For example, in the above-described embodiment, the case where the light emitter 6 is an LED has been described as an example. However, the light emitter 6 may be a cathode tube and may be provided integrally with the fluorescent portion 8. In addition, the present invention can be variously modified and modified such that the emission wavelength band (excitation light wavelength band) of the luminous body is not limited to the blue range, and may be the ultraviolet range (near ultraviolet range, etc.).

It is a schematic block diagram which shows an example of the light source device and display apparatus which have the fluorescent substance which concern on this invention. It is a schematic block diagram which shows the other example of the light source device which has the fluorescent substance which concerns on this invention. It is explanatory drawing with which it uses for description of the fluorescent substance which concerns on this invention. It is explanatory drawing with which it uses for description of the fluorescent substance which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Display apparatus, 2 ... Light source device (backlight apparatus), 3 ... Optical apparatus (liquid crystal device), 4 ... Reflector (reflection sheet), 5 ... Reflector, 6 ... Illuminant, 7 ... light guide, 8 ... fluorescent part, 8a ... first fluorescent part, 8b ... second fluorescent part, 9 ... diffusion sheet, 10 ... deflecting plate, DESCRIPTION OF SYMBOLS 11 ... TFT glass substrate, 12 ... Dot electrode, 13 ... Liquid crystal layer, 14 ... Alignment film, 15 ... Electrode, 16 ... Black matrix, 17a ... 1st color filter , 17b ... second color filter, 17c ... third color filter, 18 ... glass substrate, 19 ... deflection plate, 21 ... first prism sheet, 22 ... second Prism sheet

Claims (8)

A phosphor containing at least Eu, an A element, a D element, an E element, and an X element,
The above-mentioned Eu is contained in a ratio of 2.0 mol% or more and 5.0 mol% or less.
(Where A is one or more elements selected from the group consisting of divalent metal elements, D is one or more elements selected from the group consisting of tetravalent metal elements, E Is one or more elements selected from the group consisting of trivalent metal elements, and X is one or more elements selected from the group consisting of N, C, and O.) The phosphor according to claim 1, wherein the A element is Ca, the D element is Si, and the E element is Al. The phosphor according to claim 1, wherein the phosphor has at least a part of the same crystal structure as CaAlSiN ₃ . The phosphor according to claim 1, wherein the ratio is 2.5 mol% or more and 4.0 mol% or less. A light source device having a phosphor,
The phosphor is
Including at least Eu, A element, D element, E element, and X element,
The Eu is contained at a ratio of 2.0 mol% or more and 5.0 mol% or less.
(Where A is one or more elements selected from the group consisting of divalent metal elements, D is one or more elements selected from the group consisting of tetravalent metal elements, E Is one or more elements selected from the group consisting of trivalent metal elements, and X is one or more elements selected from the group consisting of N, C, and O.) The light source device according to claim 5, further comprising at least one kind of phosphor separately from the phosphor. A display device including a light source device having a phosphor,
The phosphor is
Including at least Eu, A element, D element, E element, and X element,
The Eu is contained in a ratio of 2.0 mol% or more and 5.0 mol% or less.
(Where A is one or more elements selected from the group consisting of divalent metal elements, D is one or more elements selected from the group consisting of tetravalent metal elements, E Is one or more elements selected from the group consisting of trivalent metal elements, and X is one or more elements selected from the group consisting of N, C, and O.) The display device according to claim 7, further comprising at least one kind of phosphor separately from the phosphor.

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