JP4579065B2 - Illumination device and display device including the same - Google Patents

Illumination device and display device including the same Download PDF

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JP4579065B2
JP4579065B2 JP2005182851A JP2005182851A JP4579065B2 JP 4579065 B2 JP4579065 B2 JP 4579065B2 JP 2005182851 A JP2005182851 A JP 2005182851A JP 2005182851 A JP2005182851 A JP 2005182851A JP 4579065 B2 JP4579065 B2 JP 4579065B2
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light
phosphor
film
guide plate
green
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JP2007005098A5 (en
JP2007005098A (en
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範宏 出島
慎 栗原
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セイコーインスツル株式会社
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  The present invention relates to an illuminating device that illuminates a display element used in a portable information device, a cellular phone, and the like, and a display device using the same. Specifically, the present invention relates to a phosphor film used for an illumination device.

  In recent years, liquid crystal display devices that can obtain high-definition color images with low power consumption have been used as display devices used in mobile phones and mobile computers. In particular, a cellular phone uses a reflective liquid crystal display device having a large opening and a bright, and a double-sided visible type liquid crystal display device capable of displaying image information from both the front and back surfaces. In order to illuminate a liquid crystal element used in a liquid crystal display device, an illuminating device using a high-intensity white LED is frequently used. In this white LED, a green phosphor or a yellow phosphor dispersed in a resin is arranged on the light emitting surface of a blue LED element as a light source, and the resulting green or yellow light and the original blue light are mixed. In general, a structure in which white light is obtained is obtained.

In the white LED having such a configuration, it is known that the fluorescent material is applied and formed on the back surface of the light guide plate at a predetermined formation density in order to prevent light deterioration of the fluorescent material because the intensity of light applied to the fluorescent material is strong. (For example, see Patent Document 1). Furthermore, in order to perform wavelength conversion with a phosphor having a smaller area, a configuration in which a layered wavelength converter is provided between a blue LED element and a light incident surface of a light guide plate is known (for example, Patent Document 2). See).
Japanese Patent Laid-Open No. 7-176794 (2nd page, FIG. 1) Japanese Patent Laid-Open No. 10-269822 (term 3, FIG. 1)

  FIG. 13 is a chromaticity diagram for explaining the emission color when using yellow phosphor particles that convert blue light into yellow light. Yellow light excited by blue light (chromaticity 101 in the figure) is indicated by chromaticity 102. Therefore, by adjusting the ratio of the yellow light intensity by changing the intensity of the blue light or adjusting the concentration of the yellow phosphor particles, the light emission of an arbitrary chromaticity connecting the chromaticity 101 and the chromaticity 102. Color can be obtained. At this time, strictly speaking, the light obtained by converting the blue light includes components other than the yellow light, and therefore, it is possible to express the chromaticity on a line having a width connecting the chromaticity 101 and the chromaticity 102. It becomes possible. However, since the width of the line connecting the chromaticity 101 and the chromaticity 102 is not wide, the color that can be reproduced using only blue light and the yellow phosphor covers the entire range of the wide color triangle 103 shown by RGB in FIG. It cannot be expressed.

  In order to solve this problem, a combination of green phosphor particles that convert blue light into green light and red phosphor particles that convert blue light into red light at a predetermined ratio is combined as phosphor particles 4. It is good to mix with the agent 2. As such phosphor particles, so-called chalcogenide compound phosphor particles such as S compounds doped with rare earth elements, Se compounds, and Te compounds are suitable. The chromaticity diagram at this time is shown in FIG. In FIG. 12, green phosphor particles excited by blue light having chromaticity 18 emit green light having chromaticity 19, and red phosphor particles excited by blue light having chromaticity 18 are red light having chromaticity 20. Is emitted. The emission intensities of green light and red light depend on the wavelength conversion efficiency and mixed concentration of green phosphor particles and red phosphor particles, and the intensity of blue light that is excitation light. Therefore, by adjusting the mixing ratio and mixing concentration of the green phosphor particles and the red phosphor particles and changing the blue light intensity, all the colors in the triangle connecting the chromaticity 18, the chromaticity 19 and the chromaticity 20 are obtained. The light corresponding to can be obtained. It can be seen that this triangle occupies most of the color triangle 103 shown in RGB, and the color specification range is widened.

  However, the properties of the chalcogenide compound phosphor particles described above tend to deteriorate when they absorb moisture, and are difficult to use regularly.

  Thus, in the case of a method for obtaining white light by additive color mixing by converting the wavelength of light from a light source using a film coated with a conventional phosphor, an S compound, Se compound, or Te compound having particularly high light conversion efficiency. When a so-called chalcogenide phosphor doped with a rare earth element is used, the phosphor deteriorates due to environmental moisture, and there is a problem that efficient color mixing cannot be performed for a long time.

  The present invention realizes a phosphor film having a long life even when a chalcogenide phosphor is used, and by using this, a liquid crystal having an efficient and wide color reproduction range without greatly affecting the design of the light guide. An object is to provide a display device.

  In the phosphor film of the present invention, a phosphor layer is formed by coating phosphor particles mixed with a binder on a translucent film substrate, and the surface of the phosphor layer is a first water-impermeable material layer. It was set as the structure coat | covered with. According to such a phosphor film, even when a chalcogenide phosphor material is used as the phosphor particles, it is possible to maintain the characteristics over a long period of time without being affected by environmental moisture.

  When the translucent film is thin, the translucent film itself is used as a non-water-permeable material, or a second non-water-permeable material layer is formed on the translucent film and the fluorescent film is formed thereon. By applying the body layer and further coating it with the first water-impermeable material layer, the phosphor layer can be isolated from the environmental moisture. As a result, the characteristics of the phosphor particles can be maintained over a long period.

  Further, the illumination device of the present invention has a light guide plate that propagates the light from the light source and the wavelength converted light obtained by exciting the phosphor with the light from the light source and irradiates it in a planar shape, A phosphor layer formed by mixing and dispersing phosphor particles in a binder as a phosphor is coated with the first water-impermeable material layer or the first water-impermeable material layer and the second water-impermeable material layer so as to be translucent. A phosphor film formed on the film is used. Then, using a blue light source as a light source, a green phosphor that converts blue light into green light and a red phosphor that converts blue light into red light are each spatially separated. Further, among the two types of phosphors, a phosphor that converts to excitation light having a shorter wavelength was disposed on the light source side.

  With such a configuration, efficient wavelength conversion can be performed using a uniform phosphor distribution without changing the propagation characteristics of the light guide plate. In addition, by forming the phosphor layers spatially separated, it is possible to place a phosphor layer with a lower wavelength conversion efficiency near the light source, and as a result, maximize the color conversion efficiency for each color. Became possible. Furthermore, since the phosphor particles are not affected by the moisture of the environment, it is possible to extend the life of the lighting device itself.

  Further, an ultraviolet light source and a blue light source are used as the light source, and a green phosphor layer that converts ultraviolet light into green light and a red phosphor layer that converts ultraviolet light into red light are used as the phosphor layer. As a result, green light emission and red light emission with high luminous efficiency can be realized, and by mixing this with blue light, a liquid crystal display device with a wide color reproduction range can be realized.

  When an ultraviolet light source is used as the light source, a phosphor layer is provided between the light source and the light guide plate incident surface, and an ultraviolet absorbing film is provided between the phosphor layer and the light guide plate incident surface. With such a configuration, it is possible to prevent the polymer components such as the light guide plate from being deteriorated by ultraviolet rays, and it is possible to extend the life of the lighting device.

  Further, the phosphor layer can be formed on a light-transmitting film by mixing phosphor particles in a polymer binder and printing or applying the phosphor particles in a predetermined shape. Further, a water-impermeable material layer was formed on the phosphor layer. The phosphor layer includes a first phosphor layer in which the first phosphor particles are dispersed in the polymer binder on the translucent film, and a second phosphor particle in which the second phosphor particles are dispersed in the polymer binder. The two phosphor layers were arranged in the plane without overlapping each other. With such a configuration, it is possible to perform wavelength conversion to multiple colors with a single phosphor layer. Since the phosphors do not overlap each other, light absorption by other phosphors can be reduced, and the wavelength conversion efficiency can be substantially improved. At this time, the region where each phosphor layer is formed is sufficiently small and close to each other, thereby improving the color mixing characteristics and enabling wavelength conversion without color unevenness. Moreover, the characteristic lifetime of the phosphor could be extended by covering the phosphor layer with the first water impermeable material layer or the first and second water impermeable material layers in this way.

  The area density of the light emitting layer to be dispersed was proportional to the required excitation light intensity. As a result, a liquid crystal display device having a uniform color mixing ratio could be obtained.

  On the other hand, as a method that does not use the phosphor layer, the first phosphor particles and the second phosphor particles are predetermined in a light pipe that propagates light from a light source and linearly irradiates the light incident surface of the light guide plate. In the light pipe, wavelength conversion and color mixing were performed simultaneously. The surface of the light pipe was covered with a water-impermeable material layer.

  Dispersing the phosphor in the light pipe enables wavelength conversion within a uniform and strong light intensity, thereby improving the wavelength conversion efficiency. Further, since the light from the light source repeats multiple reflections in the light pipe, it is possible to improve the light color mixing. Then, by covering the light pipe with the water-impermeable material layer, the phosphor can be protected from environmental moisture, and its lifetime can be extended.

  Further, the phosphor film and the light pipe are used in combination. This is because the first phosphor particles are dispersed in a light pipe that propagates light from the light source and linearly irradiates the light incident surface of the light guide plate, and between the light pipe and the light incident surface of the light guide plate. This is a structure in which the above phosphor film in which the second phosphor is arranged is arranged. In this case as well, the surface of the light pipe was covered with a water-impermeable material layer. With such a configuration, the phosphor can be mixed and dispersed uniformly in the light pipe, and more uniform color conversion can be achieved. In addition, since the light intensity applied to the phosphor layer is uniform, the phosphor film can be uniformly applied to the phosphor film, and the production thereof becomes easy.

  As described above, the phosphor film of the present invention can be used as a wavelength conversion film having high color conversion efficiency and excellent moisture resistance, and can be used for wavelength conversion of light source light in various applications. This has the effect of facilitating the reduction in power consumption, size and thickness of the color light source.

  In addition, the lighting device of the liquid crystal display device of the present invention is excellent in moisture resistance, has a long lifetime, has a wide color display region, and has a high light utilization efficiency. It has the effect that it can be set as a lighting device.

  In addition, by using the lighting device of the present invention for a liquid crystal display device, the colorimetric properties of the elements are improved, and a color liquid crystal display device with higher definition can be realized.

  Furthermore, since the lighting device of the liquid crystal display device of the present invention is resistant to the humidity contained in the environment, it is suitable for a liquid crystal display device used in a hot and humid environment such as in-vehicle use in summer.

  Moreover, the lighting device of the liquid crystal display device of the present invention can be realized as a wall-mounted lighting device with low power consumption by improving the general lighting environment by using a flat lighting device used in a general room or the like. As well as resource saving.

  The illuminating device of the present invention includes a light source, a phosphor that is excited by light from the light source, and a light guide plate that propagates light and excitation light from the light source to irradiate in a planar shape. A film, a phosphor layer provided on a light-transmitting film and phosphor particles mixed with a binder, and a non-water-permeable material layer provided on the surface of the phosphor layer are provided.

  Here, the phosphor is composed of a first phosphor that is excited by light from the light source and emits excitation light in the first wavelength range, and a second phosphor that emits excitation light in the second wavelength range. . At this time, a phosphor that emits light having a short wavelength as excitation light was disposed on the light source side. Alternatively, the first phosphor and the second phosphor are arranged in the plane so as not to overlap each other.

  In addition, the phosphor was provided between the light source and the light guide, and the mixing density of the phosphor particles was set so as to increase in the region closer to the light source.

  Or the intensity | strength of the light radiate | emitted from a light guide can be adjusted by changing the mixing density of a fluorescent substance particle according to the position in a fluorescent substance. For example, the mixing density of the phosphor particles is set to be inversely proportional to the radiation intensity distribution of the light source.

  In addition, a light pipe is provided between the light source and the light guide plate so that light from the light source propagates and linearly enters the light guide plate, a phosphor layer is formed in the light pipe, and the entire surface of the light pipe A water-impermeable material layer was provided so as to cover.

  Alternatively, a light pipe is provided between the light source and the light guide plate so that light from the light source propagates and the light is incident linearly on the light guide plate, and phosphor particles of the first phosphor are provided in the light pipe. The non-water-permeable material layer is provided so as to cover the entire surface of the light pipe, and the second phosphor is provided between the light pipe and the light incident surface of the light guide plate.

  FIG. 1 schematically shows a cross-sectional configuration of the phosphor film of this example. As shown in FIG. 1, the phosphor film has a configuration in which a binder 2 in which phosphor particles 4 are mixed is applied on a translucent film 1. Hereinafter, the layer made of the binder 2 mixed with the phosphor particles 4 will be referred to as a phosphor layer. The first water-impermeable material layer 3 is formed on the phosphor layer in which the phosphor particles 4 are mixed with the binder 2 in order to block moisture from the environment. As a material for forming the first water impermeable material layer 3, silicon resin, cycloolefin resin, fluoride resin, or the like can be used. Moreover, inorganic water-impermeable materials such as glass sol and silicon dioxide sol can also be used. The thicker the non-water-permeable material layer 3 is, the better. However, the effect appears at about 5 μm or more. In particular, in the case of using a polymer water-impermeable material layer, about 20 μm or more is desired and 50 μm or more is sufficient.

  The translucent film 1 is formed from a translucent polymer material having a thickness of about 25 to 500 μm. As this translucent polymer material, ordinary resins such as PET (polyethylene terephthalate), PC (polycarbonate), acrylic resin, and TAC (triacetyl cellulose) can be used. As the binder 2, an acrylic adhesive, an epoxy adhesive, or the like can be used. These adhesives may be thermosetting adhesives, ultraviolet curable adhesives, or natural curable adhesives. In addition, since a normal resin used as the translucent film 1 has high water permeability, particularly when the thickness of the translucent film 1 is as thin as 25 to 100 μm, the non-water-permeable polymer material layer is made of silicon resin, cyclohexane It is preferable to use an olefin resin or a fluoride resin.

The material for the phosphor particles 4 is appropriately selected depending on the excitation light wavelength to be used and the target fluorescence wavelength. For example, if the intensity of blue light, which is excitation light, is adjusted using blue light as excitation light and a yellow phosphor that converts blue light into yellow light as phosphor particles 4, excitation light and wavelength-converted light are used. Light having a desired chromaticity can be obtained by the additive color mixture.
(Specific example 1)
A PET film having a thickness of 200 μm is used as the translucent film, and the S-based green phosphor particles and the S-based red phosphor particles are added to the epoxy resin at a ratio of 1: 1, and the total weight concentration with respect to the epoxy resin is 40%. What was mixed was applied. This phosphor layer was covered with a silicon resin having a thickness of 100 μm. When the change was examined while measuring the chromaticity of the film transmitted light obtained by irradiating the sample with blue light from a blue LED in a 90% 60 ° C. environment, a non-water-permeable material layer was not formed. This sample deteriorated in 24 hours, whereas this sample showed no deterioration in characteristics even after 1000 hours.
(Specific example 2)
A phosphor layer similar to that in Example 1 was formed using a cycloolefin resin (Zeonor: Nippon Zeon brand name) having a thickness of 200 μm as the translucent film. This phosphor layer was coated with PTFE (tetrafluoroethylene resin) enamel having a thickness of 100 μm. When this was tested in the same manner as in Example 1, no deterioration was observed even after 1000 hours.

FIG. 2 schematically shows a cross-sectional configuration of the phosphor film of this example. This example is different from Example 1 in that a second water-impermeable material layer 5 is formed on the translucent film 1. As the second water-impermeable material layer 5, the same material as that of the first water-impermeable material layer 3 can be used. By forming the second water-impermeable material layer 5 in this way, a good waterproof effect can be obtained even if a normal light-transmitting film material such as PC is used for the light-transmitting film 1.
(Specific example 3)
5 μm of silicon dioxide sol was formed on a 50 μm thick PET film, and 100 μm of the same phosphor layer as in Example 1 was formed thereon. On top of that, a fluorine-containing epoxy adhesive was applied and cured to form a water-impermeable material layer 3 having a thickness of 120 μm. When the change in the emission color was examined in the same manner as in Specific Example 1 and Specific Example 2, no deterioration was observed over 1000 hours.
(Specific example 4)
A 2 μm silicon dioxide sol was formed on a 100 μm thick PFA (tetrafluoroethylene perfluorovinyl ether copolymer) film in the same manner as in Example 3, and then a phosphor layer and a fluorine-containing silicon resin were formed 200 μm thereon. When the chromaticity of the emitted color was evaluated, no deterioration was observed over 1000 hours.

  FIG. 3 is a cross-sectional view schematically showing the configuration of the illumination device of this embodiment. As shown in FIG. 3, a first phosphor film 9 is provided between the light source 6 and the light guide plate 7, and a second phosphor film 10 is provided between the reflector plate 8 and the light guide plate 7.

  The light guide plate 7 is made of a transparent polymer such as an acrylic resin, a polycarbonate resin, or a cycloolefin resin. The light guide plate 7 takes light from the light source 6 from the light incident surface and propagates the light into the inside. In general, a fine prism group or a scattering structure is formed on the light exit surface or the back surface of the light guide plate 7, and uniform light on the surface is irradiated from the light exit surface. The light sources 6 are blue LEDs, and usually two or more are arranged on the light incident surface of the light guide plate. In the embodiment shown in FIG. 3, a fine prism group is formed on the back surface of the light guide plate 7, and light propagating through the inside is taken out to the back surface at a predetermined ratio, and the light irradiated from the back surface is reflected by the reflection plate 8. Then, the light is again transmitted through the light guide plate 7 and irradiated from the light exit surface of the light guide plate 7. As the reflector 8, a reflective layer obtained by depositing Al, Ag, an alloy of Ag and Pd or the like on a polymer base material such as PET, or a transparent high-mixed white pigment having a high reflectance is used. A molecular substrate or the like can be used.

  The first phosphor film 9 and the second phosphor film 10 each have a structure in which phosphor layers using different phosphor particles are coated and coated with a non-water-permeable material layer. It is the phosphor film shown in Example 2. Specifically, in the present embodiment, the first phosphor film 9 is transparent on a transparent polyethylene terephthalate (PET) film in which a red phosphor layer that converts the wavelength of blue light into red light is coated with a second water-impermeable material layer. A silicone resin binder or an epoxy resin binder is applied as a binder. And the 1st water-impermeable material layer is apply | coated to the surface of this red fluorescent substance layer. The second phosphor film 10 is a green phosphor layer for converting blue light to green light, and a transparent silicon resin binder is coated on a transparent PET film coated with the second water-impermeable material layer as a base material. Has been. And the 1st water-impermeable material layer is apply | coated to the surface of this green fluorescent substance layer.

  Since the light applied to the second phosphor film 10 has a uniform intensity, the phosphor layer applied to the second phosphor film 10 can be applied uniformly. Further, the phosphor layer applied to the first phosphor film 9 may be applied to at least a region irradiated with light from the light source 6.

  On the other hand, when wavelength conversion of light having a shorter wavelength is generally performed, the wavelength conversion efficiency decreases as the wavelength of light obtained by wavelength conversion becomes longer. Therefore, to obtain converted light having the same light intensity, it is necessary to increase the irradiation light intensity as the conversion wavelength increases. Therefore, blue light can be efficiently converted into red light by arranging the red phosphor in the vicinity of the light source 6. Moreover, since the absorption coefficient with respect to red light of the transparent polymer material which forms the light-guide plate 7 may be compared with green light and blue light, even if the optical path after conversion becomes long, the loss until it irradiates is reduced. be able to.

  On the other hand, since the green phosphor that converts the wavelength from blue light to green light has better wavelength conversion efficiency than the red phosphor, it is arranged on the second phosphor film 10 to perform uniform wavelength conversion.

  With such a configuration, a lighting device having a wide color range and excellent moisture resistance can be realized.

  FIG. 4 schematically shows the configuration of the illumination device of the present embodiment. In this example, the first phosphor film 9 was disposed on the back surface of the light guide plate 7, and the second phosphor film 10 was disposed on the surface of the light guide plate 7. A blue LED having an emission wavelength of 460 nm was used as the light source. A red phosphor was used for the first phosphor film 9 and a green phosphor was used for the second phosphor film 10. With such a configuration, it is possible to obtain an illumination device that has excellent moisture resistance and a wide color range.

  In addition, since the blue light passing through the first phosphor film 9 is used twice by irradiation light from the light guide plate 7 side and reflected light from the reflection plate 8 side, the wavelength of the blue light is converted only once. As compared with the above, the phosphor concentration contained in the first phosphor film 9 can be halved.

  In this embodiment, since the light propagating through the light guide plate 7 is substantially only blue light, the structure design of the light guide plate for irradiation from the light exit surface can be facilitated, and the illumination efficiency can be improved. It was possible to improve the design delivery time. In addition, as a means for taking out and irradiating light propagating through the light guide plate 2 to the outside, this makes it possible to efficiently generate a hologram other than using a fine prism group or a fine scattering structure on the light exit surface or the back surface of the light guide plate 7. It became possible to use. This hologram can be easily manufactured by transferring a pattern obtained by two-beam interference fringes by lithography or forming a computer generated hologram such as a Lippmann hologram by lithography.

  Further, in this embodiment, as shown in FIG. 9, the phosphor layer 12 can be directly formed on the reflecting surface of the reflecting plate 8.

  FIG. 5 is a schematic cross-sectional view showing the configuration of the illumination device of this example. The difference between the present embodiment and the fourth embodiment is that both the first phosphor film 9 and the second phosphor film 10 are arranged on the light emitting surface side of the light guide plate 7. Since the light emitted from the light guide plate 7 has a light intensity distribution having a uniformity of 70% or more, it is obtained by wavelength conversion by the first phosphor film 9 and the second phosphor film 10 with such an arrangement. The excitation light intensity was made uniform and the color mixing property was improved. Furthermore, the wavelength conversion efficiency could be improved by using a red phosphor for the first phosphor film 9 and a green phosphor for the second phosphor film 10.

  And compared with the case where the normal phosphor film not covered with the non-water-permeable material layer is used, the moisture resistance is excellent by using the phosphor film of the present invention shown in the first example or the second example. The lighting device could be used.

  FIG. 6 shows a schematic cross-sectional configuration of the lighting apparatus of the present embodiment. In this embodiment, the first phosphor film 9 and the second phosphor film 10 are provided between the light source 6 and the light incident surface of the light guide plate 7. Also in this case, the wavelength conversion efficiency could be improved by using a red phosphor for the first phosphor film 9 and a green phosphor for the second phosphor film 10.

  In the present embodiment, since the first phosphor film 9 and the second phosphor film 10 are close to the light source 6, the light intensity distribution applied to these phosphor layers is increased. For this reason, the light intensity of the light emitted from the phosphor layers after being wavelength-converted becomes uneven when the colors are mixed inside the light guide plate because the portion where the intensity of the excitation light is large becomes strong. Therefore, the portion where the excitation light irradiation intensity is high has a small phosphor thickness applied to the phosphor layer, and the portion where the excitation light irradiation intensity is low is increased the phosphor thickness applied to the phosphor layer, so that the excitation light And the ratio of the emitted light obtained by wavelength conversion to be almost constant.

  As the light source 6, a light source in which an ultraviolet LED that emits near ultraviolet light and a blue LED that emits blue light are arranged close to each other can be used. The ultraviolet LED has an emission wavelength of 365 nm, for example, and has high excitation energy with respect to the phosphor, so that highly efficient wavelength conversion can be performed. However, since the ultraviolet rays are greatly absorbed by the constituent members of the lighting device such as the polymer material constituting the light guide plate 7, it is difficult to propagate the ultraviolet rays into the light guide plate and uniformly excite the phosphor in a wide area. It is. Therefore, as shown in FIG. 6, the efficiency can be improved by arranging a phosphor layer in the gap between the ultraviolet LED and the light guide plate 7 to propagate the visible light after conversion in the light guide plate.

  FIG. 10 is a plan view schematically showing the concentration distribution of the phosphor applied to the first phosphor film 9 and the second phosphor film 10 when three light sources are arranged in parallel. In FIG. 10, the concentration of the phosphor particles increases in the order of regions 14, 15, and 16. The region 14 corresponds to the luminance center of the light source, and the irradiation light intensity is the strongest, and the irradiation light intensity decreases with increasing distance from the luminance center. In general, the stronger the irradiation light intensity of the phosphor, the higher the wavelength conversion efficiency and the more the converted light component. Therefore, it is possible to obtain illumination light with a uniform color distribution by increasing the concentration of the phosphor as the distance from the luminance center of the light source increases. In the figure, the area is divided into three areas 14, 15, and 16 corresponding to each light source, but the color distribution can be improved by dividing the area into more areas.

  The production of such a region can be easily obtained by sequentially printing phosphor layers having different phosphor concentrations using a printing plate corresponding to each region by screen printing, offset printing, or the like. The phosphor film 9 is formed in such a manner that a non-water-permeable material layer is formed on the phosphor layer so that moisture in the environment does not affect the phosphor particles.

In this way, by providing a distribution in the phosphor concentration formed in the first phosphor film 9 and the second phosphor film 10 in FIG. 6, the illumination device is excellent in moisture resistance, colorimetric characteristics, and color mixing. Could get.
(Specific example 5)
In FIG. 6, three light sources 6 in which ultraviolet LEDs and blue LEDs are placed close to each other and enclosed in one package are arranged in parallel. The emission wavelength of the ultraviolet LED was 365 nm, and the emission wavelength of the blue LED was 470 nm. On the translucent film, the red phosphor particles having the distribution shown in FIG. 10 and mixed with the binder are screen printed and cured at a concentration of 5 levels, and further a fluorine-containing epoxy resin is applied thereon. And cured to obtain a first phosphor film. As the second phosphor film 10, a green phosphor was printed and cured in the same manner as the first phosphor film 9 and coated with a fluorine-containing epoxy resin.

  In this way, the red LED and the green light are excited by the ultraviolet LED and mixed with the blue light from the blue LED, so that an illumination device having a wide color reproduction range and a good color mixing property has been achieved. . In particular, the ultraviolet light used as excitation light has no effect on color reproduction, and it is only necessary to consider the mixed color of excited red light, green light, and blue light from a blue light source. And was able to.

  Note that ultraviolet light promotes deterioration of a polymer material such as a light guide plate that is a component of the lighting device, and the liquid crystal deteriorates when the liquid crystal device is irradiated with light mixed with ultraviolet light. In addition, it has an adverse effect on the eyes of the observer. Therefore, although not explicitly shown in FIG. 6, an ultraviolet absorbing film is inserted between the second phosphor film 10 and the light incident surface of the light guide plate 7 in this specific example.

  FIG. 7 is a perspective view schematically showing the configuration of the illumination device of the present embodiment. In the present embodiment, two blue light sources 6 a and 6 b are arranged at both ends of the light pipe 11. Light emitted from these blue light sources propagates through the inside of the light pipe 11 to be uniformed, and is deflected by a prism formed on the surface of the light pipe 11 facing the light guide plate 7 or on the opposite surface thereof. The light incident surface is uniformly irradiated and guided into the light guide plate 7. In the illuminating device of the present example, a red phosphor was mixed in the light pipe 6. As a result, the wavelength of blue light is converted into red light inside the light pipe 6, and uniform wavelength conversion and color mixing can be realized. In addition, the blue light is repeatedly reflected in the light pipe 6 and the light intensity is strong, so that efficient wavelength conversion is possible. A non-water-permeable material layer (not shown) is formed on the entire surface of the light pipe 11 so that the red phosphor particles in the light pipe 11 are not deteriorated by moisture in the environment.

  On the other hand, the second phosphor film 10 shown in Example 1 or Example 2 is disposed on the back surface of the light guide plate 7, and the green phosphor layer is uniformly formed on the surface, and the green phosphor layer is further formed. The surface of the phosphor layer is covered with a water-impermeable material layer. With such a configuration, an illuminating device having excellent moisture resistance and excellent coloration and color mixing properties can be realized.

  FIG. 8 is a perspective view schematically showing the configuration of the lighting apparatus of the present embodiment. The present embodiment is different from the seventh embodiment in that the second phosphor film 10 is inserted between the light pipe 11 and the light incident surface of the light guide plate 7. As described in the seventh embodiment, the red phosphor mixed inside the light pipe 11 efficiently converts the wavelength of the blue light into red light by the uniform and strong blue light inside the light pipe 11. Also, blue light and red light can be mixed sufficiently uniformly inside the light pipe. Furthermore, since the light emitted from the light pipe 11 to the light incident surface side of the light guide plate 7 is uniform, the phosphor layer applied to the second phosphor film 10 may be uniform. Moreover, since the light intensity irradiated to the 2nd fluorescent substance film 10 is strong compared with Example 7, it has the feature that the efficiency which converts blue light into green light can be made high. And since the area of the 2nd fluorescent substance film 10 can be made small compared with Example 7, the quantity of the fluorescent substance to be used can be reduced and the manufacturing cost of an illuminating device can be reduced.

  In this way, also in this example, it was possible to realize an illuminating device that was excellent in moisture resistance, and excellent in coloration and color mixing, using fewer phosphors.

  In Example 8 shown in FIG. 8, the phosphor applied to the surface of the second phosphor film 10 may be uniform and uniform. At this time, for example, when blue light is wavelength-converted with a red phosphor to obtain red light, energy required for wavelength conversion is absorbed and the intensity decreases. It is not efficient to convert blue light into green light by irradiating the green phosphor with the blue light whose intensity has dropped. Therefore, in this embodiment, the red phosphor and the green phosphor are divided on the second phosphor film 10 and selectively printed so as not to overlap each other. Thereby, excitation light can be used effectively. Specifically, as shown in FIG. 11, a pattern in which a red phosphor coating region 16 and a green phosphor coating region 17 are spaced apart from each other on a translucent film 13 is used. And green phosphor were mixed and dispersed in a binder and screen printed. Further, a non-water-permeable material layer was further coated thereon. With such a configuration, it is possible to efficiently perform wavelength conversion of two wavelengths from one light source by using one phosphor film without mixing and dispersing phosphors in the light pipe 6. In addition, each phosphor can absorb the excitation light and can be wavelength-converted with excitation light having a good intensity without weakening each other.

  In FIG. 11, the shape of the area to be divided does not necessarily have to be a rectangle, and may be a dot shape or a polygonal shape. The intensity of the light subjected to wavelength conversion can be easily adjusted by adjusting the area density of the divided regions. Further, the thickness of the phosphor layer to be printed and the concentration of the phosphor particles dispersed in the binder may be changed.

  In order to achieve sufficient color mixing, the print area should be as small as possible. By using screen printing, offset printing, or inkjet printing, the size of the printing area can be adjusted to an arbitrary size of 50 to 200 μm, and sufficient color mixing is possible. By changing the size of the printing region and changing the phosphor particle concentration in each region, it is possible to easily form a phosphor layer substantially having a phosphor concentration distribution as shown in FIG. It becomes possible.

  Further, it goes without saying that the formation of the phosphor forming regions dispersed in this manner can be applied to cases other than arranging the phosphor layer in the gap between the light source and the light incident surface of the light guide plate.

  As described above, the illuminating device according to the present invention can be an illuminating device that is excellent in moisture resistance and has excellent color and color mixing properties, and can be used for a high-definition liquid crystal display device. In addition to improving the brightness, it is possible to increase the brightness.

  Of course, it goes without saying that the phosphor film and the illuminating device of the present invention can be used not only as an illuminating device of a liquid crystal display device but also as a general flat light source or illuminating device.

  FIG. 14 schematically shows a configuration of a display device according to the present invention. An illumination device having the configuration described in the above embodiment is provided to illuminate the liquid crystal display element. That is, the diffusion plate 24 is disposed on the light guide plate 7, and the liquid crystal display element 23 is provided thereon. A reflection sheet 8 is provided below the light guide plate 7. These components are protected and held by the housing 25. The light source 6 mounted on the wiring substrate 21 is disposed on one end face of the light guide plate 7 and faces the light guide plate 7 without being displaced. Although not shown in FIG. 14, it goes without saying that the phosphor film is disposed at any location around the light guide plate 7 as in the above-described embodiment.

It is sectional drawing which shows typically the structure of the fluorescent substance film of this invention. It is sectional drawing which shows typically the structure of the fluorescent substance film of this invention. It is a schematic diagram which shows the structure of the illuminating device by this invention. It is a schematic diagram which shows the structure of the illuminating device by this invention. It is a schematic diagram which shows the structure of the illuminating device by this invention. It is a schematic diagram which shows the structure of the illuminating device by this invention. It is a perspective view which shows typically the structure of the illuminating device by this invention. It is a perspective view which shows typically the structure of the illuminating device by this invention. It is a schematic diagram which shows the structure of the fluorescent substance layer used for the illuminating device of this invention. It is a schematic diagram which shows the structure of the fluorescent substance layer used for the illuminating device of this invention. It is a schematic diagram which shows the structure of the fluorescent substance layer used for the illuminating device of this invention. It is a chromaticity diagram which shows the color specification of the illuminating device of this invention. It is a chromaticity diagram which shows the color specification of the conventional illuminating device. It is sectional drawing which shows typically the structure of the liquid crystal display device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Translucent film 2 Binder 3 1st water-impermeable material layer 4 Phosphor particle 5 2nd water-impermeable material layer 6 Light source 7 Light guide plate 8 Reflector 9 First phosphor film 10 Second phosphor film 11 Light Pipe 12 Phosphor layer 13 Translucent film 16 Red phosphor coating region 17 Green phosphor coating region 21 Wiring substrate 23 Liquid crystal display element 24 Diffusion plate 25 Housing

Claims (3)

  1. A blue LED element ;
    A light guide plate that propagates light from the blue LED element and irradiates it in a planar shape from the irradiation surface;
    Wherein is arranged above the irradiated surface of the light guide plate is excited by the light from the blue LED element to emit from the irradiated surface, the red phosphor film that emits red light,
    A green phosphor film disposed above the irradiation surface of the light guide plate and excited by light from the blue LED element emitted from the irradiation surface to emit green light ;
    In the red phosphor film, a red phosphor layer containing chalcogenide-based red phosphor particles for converting blue light into red light is provided on the first translucent film, and only on the red phosphor layer. Is provided with a polymer non-water-permeable material layer,
    In the green phosphor film, a green phosphor layer containing chalcogenide-based green phosphor particles for converting blue light into green light is provided on the second light-transmitting film, and only on the green phosphor layer. Is provided with a polymer non-water-permeable material layer,
    The first translucent film and the second translucent film are formed of a translucent polymer material having a thickness of 25 to 500 μm,
    The lighting device, wherein the polymer impermeable material layer is formed on the red phosphor layer and the green phosphor layer with a thickness of 20 μm or more .
  2. The lighting device according to claim 1 , wherein the red phosphor film is disposed closer to the irradiation surface than the green phosphor film.
  3. A display device comprising: the illumination device having the configuration according to claim 1; and a liquid crystal display element illuminated by light from an irradiation surface of the illumination device.
JP2005182851A 2005-06-23 2005-06-23 Illumination device and display device including the same Active JP4579065B2 (en)

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JP2005182851A JP4579065B2 (en) 2005-06-23 2005-06-23 Illumination device and display device including the same
US11/430,615 US20060268537A1 (en) 2005-05-31 2006-05-09 Phosphor film, lighting device using the same, and display device
KR1020060048639A KR20060125535A (en) 2005-05-31 2006-05-30 Phosphor film, lighting device using the same, and display device

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