JP4797944B2 - Light source device and display device - Google Patents

Description

The present invention relates to a light source device having a fluorescent member having a 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.

The backlight is generally configured to use a cold cathode tube. However, a light emitting diode (LED) with high luminous efficiency has been developed, and research on using this for a light source (light emitting body) of a backlight is underway.
As a light emitter used for a backlight, an LED emitting blue light, a so-called blue light-emitting diode, has attracted attention. As a specific example of the light source device using this blue LED, there is a so-called white LED in which phosphors (yellow phosphors) that convert yellow light are distributed around the blue LED and white is obtained by combining blue and yellow. Can be 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, the fluorescent substance used for a light source device is not restricted to this yellow fluorescent substance, Various things are mentioned.
For example, by combining multiple types of phosphors with different emission wavelength bands (for example, red phosphor and green phosphor), and further selecting the composition of each phosphor and the proportion of the combination, the desired emission characteristics Can be realized.
In this way, by selecting the phosphor itself, it is possible to approach the characteristics required in the light source device, and thus the light source device using the phosphor has attracted much attention in recent years.

However, it has been pointed out that phosphors have a remarkable decrease in light emission characteristics over time. And it is thought that this change with time is dominated by the fact that the phosphor itself is deteriorated by absorbing moisture in the air rather than spontaneously deteriorating.
In particular, some phosphors, such as sulfide phosphors, nitride phosphors, and silicate phosphors, which have been attracting attention as phosphors exhibiting excellent light emission characteristics in recent years, are composed of these phosphors due to characteristic deterioration due to water absorption. It is a serious problem to shorten the lifetime of the entire device.

On the other hand, an attempt to improve the moisture resistance of the phosphor itself has been proposed.
However, there are various characteristics required for the phosphor, and it is difficult to obtain all of these characteristics by processing the phosphor itself. In addition, pursuing moisture resistance at the expense of essential characteristics related to light emission, such as light emission intensity, light emission center wavelength, and chromaticity, is not optimal under the premise of constituting a light source device.
Japanese Patent Laid-Open No. 08-007614

The present invention has been made in view of such a problem, and an object thereof is to provide a light source device having a fluorescent member having a phosphor with improved moisture resistance, and a display device including the light source device. There is to do.

The light source device according to the present invention is a light source device having a fluorescent member, wherein the fluorescent member is a fluorescent member including at least two kinds of phosphors, and the two or more kinds of phosphors are dispersed. The plurality of dispersion layers are sandwiched between two glass sealing members disposed on the lower side and the upper side, respectively , and the end portions of the two glasses are It is hermetically sealed by being fused to each other .

The display device according to the present invention is a display device including a light source device, and the light source device is the light source device according to the present invention .

According to the light source device of the present invention, the dispersion layer in which the phosphor is dispersed is sandwiched and sealed by the sealing member made of glass so that the fluorescence member is configured. Figured. This improves the long-term reliability of the device.

According to the display device according to the present invention, since the light source device according to the present invention is provided, the moisture resistance of the fluorescent member is improved, so that the long-term reliability of the device is improved.

<Embodiment of fluorescent member, embodiment of light source device, and embodiment of display device>
Embodiments of the present invention will be described below.
The display device according to this embodiment is a display device including a light source device, and the light source device has a plurality of dispersion layers in which at least two kinds of phosphors are dispersed. Each of the plurality of dispersion layers has a fluorescent member that is configured to be sealed by a non-moisture permeable sealing member that transmits visible light.
In this embodiment, as a specific configuration example, a light source device having a blue light emitter, a first phosphor, and a second phosphor will be described.

That is, in the display device according to the present embodiment, in the light source device, the main light emission wavelength band of the first phosphor is on the longer wavelength side than the main light emission wavelength band of the light emitter, and the main phosphor of the second phosphor. It is assumed that the emission wavelength band is on the longer wavelength side than the main emission wavelength band of the first phosphor.
In the present embodiment, a phosphor that emits light in the green region is used as the first phosphor, and a phosphor that emits light in the red region is used as the second phosphor.
The first phosphor and the second phosphor are dispersed inside the first dispersion layer and the second dispersion layer, respectively, and the first dispersion layer and the second dispersion layer are hermetically sealed by a moisture-impermeable sealing member. Thus, the fluorescent member according to the present embodiment is configured.

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

The light source device 2 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, a plurality of light emitters 6 made of, for example, blue LEDs are provided as blue light sources. 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 present embodiment, a fluorescent member 8 is provided on the light guide unit 7 of the light source device 2.
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 a is provided on the back side of the light source device 2. In addition, a reflector 4b similar to the reflector 4a is also provided on the side surface of the light guide unit 7 as necessary. As the resin, various transparent resins can be used in addition to epoxy, silicone, and urethane.

First phosphors of the first distribution unit 8a is different from the light emitter 6 as a green phosphor having a main emission wavelength band on the long wavelength side, for example, _{(Sr 1-xy Ca x Ba} y) Ga 2 S ₄ : Eu can 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 light emission in the green range, the emission wavelength band of the first phosphor preferably includes at least a part of 510 nm to 550 nm.
As a 2nd fluorescent substance which comprises the 2nd dispersion | distribution part 8b, CaS: Eu can be mentioned as a red fluorescent substance which has the main light emission wavelength band on the long wavelength side compared with a 1st 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 second phosphor preferably includes at least a part of 610 nm to 670 nm.

In the present embodiment, the fluorescent member 8 includes at least a first dispersion part 8a and a second dispersion part 8b in which a first phosphor and a second phosphor having different emission wavelength bands are dispersed, and the first dispersion part. 8a and the second dispersion part 8b, and the sealing member 5 arranged in close contact with the surface. And in this embodiment, this sealing member 5 has a 2nd sealing member (not shown) provided in the back surface of the 1st dispersion | distribution part 8a and the 2nd dispersion | distribution part 8b, and both ends by pressurization or heating. As a result of being fused, not only the front and back surfaces of the first dispersion part 8a and the second dispersion part 8b but also the end parts are covered and sealed.
It is preferable that the sealing member 5 is made of a material having both at least visible light permeability and non-moisture permeability (in this embodiment, the property that moisture permeation is completely or significantly suppressed). Specific examples include materials classified as glass and polymers made of polymers. In the present embodiment, it is preferable that the second sealing member is also made of the same material.

The arrangement positions of the first dispersion layer and the second dispersion layer can be appropriately selected. For example, as shown in FIG. 2, a method in which the light emitter 6 is arranged on the side surface of the light guide unit 7 (edge light method, In the side light system), it may be arranged on the light guide unit 7. In this method, the light from the light emitter 6 is reflected by the rear slope of the light guide 7 and passes through the fluorescent member 8, the first prism sheet 21, and the second prism sheet 22, and then the diffusion sheet 9. To.
In the configuration shown in FIGS. 1 and 2, the first dispersion layer 8a and the second dispersion layer 8b in the fluorescent member 8 do not overlap with each other in the main light emission direction (upward in the drawing; vertical direction). Therefore, the first dispersion layer 8a and the second dispersion layer 8b can introduce light from the light emitter 6 without going through each other, and can emit light emitted from each phosphor without going through each other. That is, according to this configuration, it is possible to avoid that the light emission of each phosphor is weakened by another dispersion layer.

As for the positional relationship between the first dispersion layer 8a and the second dispersion layer 8b, as shown in FIG. 3, the output direction of the light emitters 6 arranged in the housing 4d that also serves as a reflector (upper side in the figure). In addition, it may be arranged so as to be sandwiched or fixed by the sealing member 5. In this case, it is preferable that the second dispersion layer is disposed between the light emitter 6 and the first dispersion layer. This is because the output of the green light from the first dispersion layer 8a can be avoided from being excited by the red phosphor in the second dispersion layer 8b.
That is, according to this configuration, it is possible to reduce the ratio (loss) at which light emitted from the first dispersion layer is absorbed by the second dispersion layer. In particular, when a green phosphor is used as the first phosphor, it can be considered particularly preferable because this configuration can improve the green light emission intensity with high luminous sensitivity.

  As for the positional relationship between the first dispersion layer 8a and the second dispersion layer 8b, as shown in FIG. 4, the first dispersion layer 8a and the second dispersion layer 8b are located inside the housing 4e that also serves as a reflector. It is good also as the arrangement configuration which mutually mixed as resin which covers the light-emitting body 6 arranged, and was sealed off from the outside by the sealing member 5. Compared to the configuration described above, a configuration closer to a so-called white LED can be achieved.

As illustrated in these, the fluorescent member 8 according to the present embodiment includes the light source device 2 and the display device 1 including the arrangement of the first dispersion layer 8a and the second dispersion layer 8b, the shape of the sealing member 5, and the like. It is possible to select an arrangement shape, a positional relationship, a shape dimension, and the like according to the structure of the above.
In other words, the fluorescent member 8 may be formed more integrally with a member located near the light emitter 6 such as the light guide 7, or the light emitter 6 such as a reflective sheet or an optical film. It may be united with the member in the position away from. Moreover, it is good also as a structure which the member itself serves as the role of a dispersion layer by comprising these members with the material suitable for dispersion | distribution of fluorescent substance.

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 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 each color is improved. The black matrix 16 and the color filters 17a and 17c are attached to the glass substrate 18.

  In the display device 1 and the light source device 2 obtained by the method for manufacturing a light emitting composition according to this embodiment, an excellent light emitting composition can be manufactured at low cost, and the device is manufactured at low cost. It is also possible.

<Example>
Examples of the present invention will be described.
In this example, the result of manufacturing the fluorescent member having the above-described configuration and evaluating the characteristics thereof will be described.

The moisture resistance of a light emitting device such as a light source device or a display device greatly depends on the moisture resistance of the fluorescent member. For this reason, in this example, a comparative evaluation of the change over time of the emission intensity of the phosphor between the fluorescent member according to the present embodiment and the conventional fluorescent member (that is, the dispersion layer not sealed with the sealing member) is performed. Went.
In this characteristic evaluation, the light source device according to the above-described embodiment and the conventional light source device were left standing under the conditions of 60 ° C. and 90% RH (relative humidity), and the change over time of the emission intensity of the phosphor was compared and measured. In addition, the measurement of emitted light intensity was performed using the spectrophotometer (SPLU Co., Ltd. FLUOROLOG-3).
FIG. 5 shows the result of evaluation (measurement). In FIG. 5, the result is shown as a relative value where the initial light emission intensity is 1.

From the results shown in FIG. 5, the emission intensity of the conventional fluorescent member was significantly reduced in less than 100 hours (l in the figure), whereas in the fluorescent member according to the present example, over 500 hours. It was confirmed that the emission intensity was maintained.
Note that, as described above, the moisture resistance of the light emitting device greatly depends on the moisture resistance of the fluorescent member. Therefore, if the moisture resistance of the fluorescent member is improved, the moisture resistance of the light source device and the display device including the light emitter and the fluorescent member is improved. Improves long-term reliability. Therefore, it is considered that the light source device and the display device having the fluorescent member according to the present example are excellent in long-term reliability (particularly moisture resistance).

As described in the above embodiments, according to the light source device according to the present embodiment, in the light source device, the dispersion layer containing the phosphor is sealed by the non-moisture permeable sealing member that transmits visible light. Therefore, the lifetime of the phosphor can be extended by improving the moisture resistance.
Therefore, in the display device according to the present embodiment, it is possible to maintain excellent display characteristics for a long time.

  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, as long as the fluorescent member 8 can be directly bonded to the light guide unit 7, the second sealing member is not necessarily prepared. In addition, if the structure fused by pressurization or heating is not optimal, the end portions of the first dispersion portion 8a and the second dispersion portion 8b that are not directly covered with the sealing member 5 are sealed with the sealing member 5. It is good also as a structure covered with the fixing means (adhesive etc. which become resin after solidification).

  In the above-described embodiment, the case where the light emitter is a blue light emitting diode has been described as an example. However, a light emitter having a light emission wavelength band on a shorter wavelength side (for example, a near ultraviolet light emitting diode) is used. It is possible to use a device configuration having three kinds of phosphors of red, green, and blue, or a device configuration having more phosphors.

  In other words, various modifications and changes can be made in the present invention, such as each member and material constituting the light source device and the display device can be selected as needed including phosphors.

It is a schematic block diagram which shows the specific structural example of the light source device which has a luminescent composition obtained by an example of the manufacturing method which concerns on this invention, and a display apparatus provided with this light source device. It is a schematic block diagram which shows the other specific structural example of the light source device which has a luminescent composition obtained by an example of the manufacturing method which concerns on this invention. It is a schematic block diagram which shows the other specific structural example of the light source device which has a luminescent composition obtained by an example of the manufacturing method which concerns on this invention. It is a schematic block diagram which shows the other specific structural example of the light source device which has a luminescent composition obtained by an example of the manufacturing method which concerns on this invention. It is explanatory drawing with which it uses for description of an example of the luminescent composition obtained by an example of the manufacturing method which concerns on this invention, the light source device which has a light source device which has this luminescent composition, and a display apparatus provided with this light source device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Display apparatus, 2 ... Light source device (backlight apparatus), 3 ... Optical apparatus (liquid crystal device), 4a ... Reflector, 4b ... Reflector, 4c ... Reflector (reflection sheet) ) 5... Sealing member, 6... Light emitter, 7... Light guide portion, 8 .. Fluorescent member, 8a... First dispersion portion, 8b. DESCRIPTION OF SYMBOLS 9 ... Diffusion sheet, 10 ... Deflection plate, 11 ... TFT glass substrate, 12 ... Dot electrode, 13 ... Liquid crystal layer, 14 ... Alignment film, 15 ... Electrode, 16 ... Black matrix, 17a ... first color filter, 17b ... second color filter, 17c ... third color filter, 18 ... glass substrate, 19 ... deflecting plate, 21 ... -1st prism sheet, 22 ... 2nd prism sheet

Claims (8)

A light source device having a fluorescent member,
The fluorescent member includes at least two kinds of phosphors ,
The two or more types of phosphors each have a plurality of dispersed layers dispersed therein,
The plurality of dispersion layers are sandwiched between two glass sealing members disposed on the lower side and the upper side, respectively , and the ends of the two glasses are fused to each other, thereby sealing The light source device. A light emitter, a first phosphor, and a second phosphor;
The main light emission wavelength band of the first phosphor is on the long wavelength side compared to the main light emission wavelength band of the light emitter,
The main emission wavelength band of the second phosphor is on the longer wavelength side than the main emission wavelength band of the first phosphor,
Wherein the first phosphor and the second phosphor, respectively, are distributed in the interior of the first dispersion layer and the second dispersion layer,
The first dispersion layer and the second dispersion layer are sealed by the sealing member .
The light source device according to claim 1 . The second dispersion layer is disposed between the light emitter and the first dispersion layer .
The light source device according to claim 1 or 2 . The first dispersion layer and the second dispersion layer are arranged such that light from the light emitter is introduced without passing through each other and light emission of the phosphor is emitted without going through each other.
The light source device according to claim 1 or 2 . The light emitter is a blue light emitting diode .
The light source device according to any one of claims 1 to 4 . The light emitter is a near ultraviolet light emitting diode;
A third dispersion layer in which a third phosphor having a main emission wavelength band on the short wavelength side is dispersed as compared with the first phosphor and the second phosphor;
The light source device according to any one of claims 1 to 4 . A display device including a light source device,
The display device according to claim 1 , wherein the light source device is the light source device according to claim 1 . The display device according to claim 7, further comprising an optical device that modulates and outputs the light from the light source device.

Images