JP2013258119A - Light-emitting device and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device which guides light emitted from a fluorescent part efficiently to a light guide plate.SOLUTION: A light-emitting device 1 is provided with a fluorescent part 10 which emits fluorescence by receiving light emitted from an LED element 2 and a light guide plate 3 which guides light emitted by the fluorescent part 10. At least a part of the fluorescent part 10 is arranged inside the light guide plate 3.

Description

  The present invention relates to a light emitting device that efficiently guides light emitted from a fluorescent part to a light guide plate, and a display device using the light emitting device.

  A light source that emits blue light or ultraviolet light from a light emitting element such as an LED (light emitting diode) and excites a phosphor with this light to emit different colors is known. It is disclosed in Document 1.

  The linear light-emitting device of Patent Document 1 includes a rectangular mounting board, a plurality of light-emitting elements arranged in the longitudinal direction on the mounting board, a phosphor layer that linearly covers the plurality of light-emitting elements, And a sealing resin that covers the phosphor layer. And in the linear light-emitting device of patent document 1, the light which the said fluorescent substance layer emits is guided to the light-guide plate arrange | positioned in the position spaced apart from the said fluorescent substance layer.

JP 2008-47851 A (published February 28, 2008)

  However, the technique of Patent Document 1 has the following problems.

  In the linear light-emitting device of Patent Document 1, a phosphor layer, a sealing resin that seals the phosphor layer, and a light guide plate are spaced apart and an air layer is interposed therebetween. At this time, since the refractive index of the sealing member and the air layer are different from each other, when the light emitted from the phosphor reaches the interface between the sealing member and the air layer, the refraction of light caused by the difference in refractive index or The proportion of light that is not guided to the light guide plate due to reflection or the like increases. This loss of light contributes to a decrease in the light emission efficiency of the light emitting device. Further, even if the phosphor layer and the sealing resin that seals the phosphor layer are brought close to the light guide plate, the light from the phosphor is emitted isotropically and therefore is not guided to the light guide plate. Light is generated.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a light-emitting device and a display device that efficiently guides light emitted from a fluorescent portion to a light guide plate. is there.

  In order to solve the above problems, a light emitting device according to the present invention includes: a fluorescent part that emits fluorescence in response to excitation light emitted from an excitation light source; and a light guide plate that guides fluorescence emitted from the fluorescent part. And the fluorescent part is characterized in that at least a part of the fluorescent part is disposed inside the light guide plate.

  Generally, the fluorescent part emits fluorescence isotropically upon receiving excitation light emitted from an excitation light source. Therefore, if the light emitted isotropically from the fluorescent part can be efficiently guided to the light guide plate, the light emission efficiency of the light emitting device can be improved.

  In this regard, in the light emitting device according to the present invention, at least a part of the fluorescent part is disposed inside the light guide plate. As a result, most of the fluorescence emitted from the fluorescent portion disposed inside the light guide plate can be directly incident on the inside of the light guide plate. Thereby, the ratio by which the light radiate | emitted from the fluorescence part is guided to a light-guide plate increases, and the light emission efficiency of a light-emitting device can be improved.

  Further, in the light emitting device according to the present invention, the fluorescent part may be configured to be entirely disposed inside the light guide plate.

  According to said structure, since all the fluorescence parts are arrange | positioned inside the light guide plate, the ratio by which the light radiate | emitted from the fluorescence part is guided to a light guide plate increases, and the luminous efficiency of a light-emitting device is improved. Further improvements can be made.

  In the light emitting device according to the present invention, the fluorescent part includes at least a first fluorescent part and a second fluorescent part, and the first fluorescent part receives the excitation light emitted from the excitation light source and emits fluorescence. The second fluorescent part emits fluorescence of a color different from that of the first fluorescent part upon receiving the excitation light emitted from the excitation light source, and among the first fluorescent part and the second fluorescent part, The fluorescent part with the longer wavelength of emitted fluorescence may be arranged at a position closer to the excitation light source than the other fluorescent part.

  In general, the fluorescent part has a characteristic that it easily absorbs light having a shorter wavelength than the fluorescence emitted from the autofluorescent part. In the light emitting device according to the present invention, of the first fluorescent part and the second fluorescent part, the fluorescent part with the longer wavelength of the emitted fluorescence is disposed at a position closer to the excitation light source than the other fluorescent part. Thereby, it can suppress that the fluorescence which the fluorescence part arrange | positioned in the position close | similar to the said excitation light source emitted is absorbed by the other fluorescence part (mutual absorption).

  Therefore, since the light emitting device according to the present invention can efficiently use the fluorescence emitted from the first fluorescent part and the second fluorescent part while suppressing mutual absorption, the luminous efficiency can be further improved. .

  In the light emitting device according to the present invention, the first fluorescent part receives light from the blue light emitting element and emits red fluorescence, and the second fluorescent part receives light from the blue light emitting element and emits green light. The structure which emits fluorescence may be sufficient.

  According to said structure, the said 1st fluorescence part receives the light of a blue light emitting element, and emits red fluorescence, The main wavelength of the light is 600 nm-680 nm. The second fluorescent part emits green fluorescence upon receiving light from the blue light emitting element, and the main wavelength of the light is 510 nm to 560 nm. That is, the wavelength of red fluorescence emitted from the first fluorescent part is longer than the wavelength of green fluorescence emitted from the second fluorescent part.

  Accordingly, the first fluorescent part is disposed closer to the excitation light source than the second fluorescent part, thereby suppressing the green fluorescent light emitted by the second fluorescent part from being absorbed by the first fluorescent part. And the luminous efficiency of the light emitting device can be further improved.

  In the light emitting device according to the present invention, the fluorescent part includes a phosphor that emits fluorescence upon receiving the excitation light, and a sealing material that seals the phosphor. The sealing material and the light guide plate May be the same refractive index, or the sealing material may have a smaller refractive index.

  In general, light hardly travels from a higher refractive index to a smaller refractive index, and light loss is likely to occur. On the other hand, light easily travels from the smaller refractive index to the larger refractive index, and light loss hardly occurs.

  Therefore, the light emitting device according to the present invention has the above-described configuration, so that the light emitted from the fluorescent part can be easily incident on the light guide plate, and the light emission efficiency can be further increased.

  In the light emitting device according to the present invention, the excitation light is emitted from the excitation light source at least one of the incident surface of the excitation light and the emission surface of the fluorescence part facing the incident surface in the fluorescence unit. The structure formed in convex shape toward the direction may be sufficient.

  The fluorescence emitted from the fluorescent part is emitted in a direction perpendicular to the light emission surface. Therefore, the light emitting device according to the present invention has the above-described configuration, thereby increasing the ratio of light guided to the inside of the light guide plate (light extraction efficiency) and reducing the ratio of return light toward the excitation light source. The emission efficiency can be further increased.

  In the light emitting device according to the present invention, the fluorescent part may include a nanoparticle phosphor.

  According to said structure, the said fluorescence part contains nanoparticle fluorescent substance. Even if a nanoparticle phosphor uses a material having the same composition, the emission color can be changed by the quantum size effect by changing the particle diameter of the material to a nanometer size.

  Therefore, while the color (wavelength) to be emitted is determined with conventional phosphor materials, the light emitting device according to the present invention can easily change the emission wavelength by changing the particle diameter with the same material. Thus, light emitting devices with various colors can be realized.

  In addition, a light emitting device according to the present invention includes a third fluorescent part that receives excitation light emitted from the excitation light source and emits fluorescence of a color different from that of the first fluorescent part and the second fluorescent part, The first fluorescent part, the second fluorescent part, and the third fluorescent part may be arranged in the vicinity of the excitation light source in order from a fluorescent part having a long wavelength of emitted fluorescence.

  The light emitting device according to the present invention can efficiently use the fluorescence emitted from the first fluorescent part, the second fluorescent part, and the third fluorescent part while suppressing mutual absorption with the above-described configuration. Can be further enhanced.

  In the light emitting device according to the present invention, the first fluorescent part receives light from the blue light emitting element and emits red fluorescence, and the second fluorescent part receives light from the blue light emitting element and emits green light. The third fluorescent part emits fluorescent light and emits yellow fluorescent light upon receiving light from the blue light emitting element, and the first fluorescent part, the third fluorescent part, and the second fluorescent part are in that order, The structure arrange | positioned in the position close | similar to the said excitation light source may be sufficient.

  According to said structure, the said 1st light emission part receives the light of a blue light emitting element, and emits red fluorescence, The main wavelength of the light is 600 nm-680 nm. The second light emitting unit emits green fluorescence upon receiving light from the blue light emitting element, and the main wavelength of the light is 510 nm to 560 nm. The third light-emitting unit emits yellow fluorescence upon receiving light from the blue light-emitting element, and the main wavelength of the light is 560 nm to 590 nm.

  That is, the wavelength of red fluorescence emitted from the first light emitting unit is the longest, and the wavelength of green emitted from the second light emitting unit is the shortest. Therefore, in the light emitting device according to the present invention, the first light emitting unit, the third light emitting unit, and the second light emitting unit are arranged in that order at a position close to the excitation light source. Mutual absorption can be further suppressed, and the light emission efficiency of the light emitting device can be further increased.

  Further, the display device according to the present invention may be configured to include any one of the above light emitting devices.

  According to the above configuration, in the display device according to the present invention, a decrease in light emission efficiency due to the refractive index of the sealing member of the fluorescent part and the air layer is suppressed, and light emitted isotropically from the fluorescent part is suppressed. Since the light can be efficiently guided to the light guide plate, a display device with high light emission efficiency can be realized.

  As described above, the light-emitting device according to the present invention includes the fluorescent part that emits fluorescence in response to the excitation light emitted from the excitation light source, and the light guide plate that guides the fluorescence emitted from the fluorescent part. The part has a configuration in which at least a part thereof is arranged inside the light guide plate.

  Therefore, the light emitted from the fluorescent part can be efficiently guided to the light guide plate.

It is the schematic of the light-emitting device which concerns on this Embodiment. It is the schematic of the other light-emitting device based on this Embodiment by which a part of fluorescence part is arrange | positioned inside a light-guide plate, and the remainder is arrange | positioned outside the light-guide plate. It is the schematic of the further light-emitting device which concerns on this Embodiment. It is the schematic of the further light-emitting device which concerns on this Embodiment. It is the schematic of the further light-emitting device which concerns on this Embodiment. It is the schematic of the further light-emitting device which concerns on this Embodiment. It is the schematic of the further light-emitting device which concerns on this Embodiment. It is a figure for demonstrating the cross-sectional shape of the fluorescence part which concerns on this Embodiment, (a) is a semi-cylindrical fluorescent part, (b) is convex toward the direction in which light is radiate | emitted from an LED element. (C) is a fluorescent part in which the incident surface on which the light emitted from the LED element is incident is convex toward the direction in which the light is emitted from the LED element. (d) is a fluorescent part in which a fluorescent emission surface facing a light incident surface on which light emitted from the LED element is incident is formed in a convex shape in the direction in which light is emitted from the LED element. Is a fluorescent portion in which an incident surface on which light emitted from an LED element is incident and an emission surface of fluorescence opposite to the incident surface are formed in a convex shape in a direction in which light is emitted from the LED element. FIG. It is the schematic of the further light-emitting device which concerns on this Embodiment. FIG. 5 is a schematic diagram when the light-emitting device according to the present embodiment is used as a light source for backlight of a liquid crystal display device. It is sectional drawing of an LED element. It is sectional drawing of an LED element.

  Hereinafter, the light-emitting device 1 and the like according to the present embodiment will be described with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[Configuration of Light Emitting Device 1]
First, the light emitting device 1 will be described with reference to FIG. FIG. 1 is a schematic view of a light emitting device 1. The light emitting device 1 includes a plurality of LED elements (excitation light sources) 2, a light guide plate 3, and a fluorescent part 10 that is disposed entirely inside the light guide plate 3.

  The plurality of LED elements 2 are light emitting elements that function as excitation light sources. The LED element 2 may be either one having one light emitting point per chip or one having a plurality of light emitting points per chip. The emission wavelength of the LED element 2 is, for example, 450 nm (blue), but an LED having a wavelength in the blue region of 420 nm to 490 nm can be selected. Or the light emission wavelength of the LED element 2 should just be suitably selected according to the kind of nanoparticle fluorescent substance (after-mentioned), Therefore It is good also as a wavelength different from blue. In addition, the LED element 2 may not be plural and may be single. The LED element 2 may use another excitation light source such as a laser.

  The light guide plate 3 is used for a backlight of a liquid crystal display, and has a role of making the fluorescence emitted from the fluorescent part 10 a uniform surface light source. The light guide plate 3 may be of any type such as an edge light type or a direct type. Further, the light guide plate 3 may take in the light emitted from the LED element 2 together with the fluorescence emitted from the fluorescent part 10.

  The fluorescent part 10 emits light upon receiving excitation light emitted from an excitation light source such as a laser or LED, and includes a phosphor that emits light upon receiving excitation light. Specifically, in the fluorescent part 10, a phosphor is dispersed inside a silicone resin (sealing material) as a phosphor holding substance. The ratio between the silicone resin and the phosphor is preferably about 10: 1, but is not limited to this ratio. Moreover, the fluorescent part 10 may be one obtained by pressing and fixing a fluorescent material. The phosphor holding substance is not limited to silicone resin, and may be so-called organic-inorganic hybrid glass or inorganic glass.

  The fluorescent part 10 is of oxynitride type, and blue, green and red phosphors are dispersed in a silicone resin. Here, as an example of an excitation light source that emits excitation light, a semiconductor light emitting element is a 450 nm (blue) LED (or an LED or laser in the vicinity of a so-called “blue” having a peak wavelength in a wavelength range of 440 nm to 490 nm. ). When the LED unit is irradiated with the LED light, for example, white light is generated from the fluorescent unit 10. That is, it can be said that the fluorescent part 10 is a wavelength conversion material. In this case, the fluorescent part 10 is a yellow phosphor or a mixture of a green phosphor and a red phosphor. The yellow phosphor is a phosphor that emits light having a peak wavelength in a wavelength range of 560 nm to 590 nm. The green phosphor is a phosphor that emits light having a peak wavelength in a wavelength range of 510 nm or more and 560 nm or less. The red phosphor is a phosphor that emits light having a peak wavelength in a wavelength range of 600 nm to 680 nm. However, the wavelength of the light emitted from the semiconductor light emitting element may be appropriately selected according to the type of the fluorescent portion 10, and thus may be a wavelength different from the wavelength of the so-called blue light.

  Further, an excitation light source that emits excitation light may be one that oscillates 405 nm (blue-violet) laser light. In this case, the fluorescent unit 10 may be a yellow phosphor, or a green phosphor and a red fluorescence. It is a mixture with the body.

The fluorescent part 10 may be a so-called sialon phosphor. Sialon is a substance in which a part of silicon atoms of silicon nitride (Si ₃ N ₄ ) is replaced with aluminum atoms and a part of nitrogen atoms is replaced with oxygen atoms. The sialon phosphor can be made by dissolving alumina (Al ₂ O ₃ ), silica (SiO ₂ ), rare earth elements and the like in silicon nitride.

  Moreover, as another suitable example of the fluorescence part 10, you may use the semiconductor nanoparticle fluorescent substance using the nanometer-sized particle | grains of a III-V group compound semiconductor. Even if compound semiconductors with the same composition (for example, indium phosphide: InP) are used, the emission color can be changed by the quantum size effect by changing the particle size. one of. For example, InP emits red light when the particle size is about 3 to 4 nm.

  Since the semiconductor nanoparticle phosphor is semiconductor-based, the fluorescence lifetime is short, and the excitation energy absorbed by the excitation light can be quickly emitted as fluorescence, so that the semiconductor nanoparticle phosphor is highly resistant to high-power excitation light. This is because the emission lifetime of the semiconductor nanoparticle phosphor is about 10 nanoseconds, which is five orders of magnitude smaller than that of a normal phosphor material having a light emission center of rare earth.

  As a result, high efficiency can be maintained against strong excitation light, and heat generation from the phosphor is reduced. Therefore, deterioration (discoloration or deformation) of the fluorescent part due to heat can be suppressed. Thereby, when using the light emitting element with a high light output as a light source, the lifetime reduction of a light-emitting device can be prevented.

  Thus, the fluorescent part 10 is not limited to a specific type, and can be appropriately selected. The fluorescent part 10 only needs to be fixed to the light guide plate 3 with an adhesive or the like.

[Effects of the light emitting device 1]
In general, the fluorescent portion receives light emitted from an excitation light source such as an LED and emits fluorescence isotropically. Therefore, it is possible to improve the light emission efficiency of the light emitting device by increasing the ratio of light isotropically emitted from the fluorescent part to the light guide plate.

  In this regard, in the light emitting device 1, the entire fluorescent portion 10 is disposed inside the light guide plate 3. As a result, most of the fluorescence emitted from the fluorescent portion 10 disposed inside the light guide plate 3 is incident on the inside of the light guide plate 3 as it is, and there is a loss of fluorescence between the fluorescent portion 10 and the light guide plate 3. Reduced. Thereby, since the light radiate | emitted from the fluorescence part 10 is efficiently guide | induced to the light-guide plate 3, the light-emitting device 1 can improve luminous efficiency.

  Here, a conventional light-emitting device, that is, a light-emitting device in which a fluorescent portion is arranged outside the light guide plate is considered. For example, when the fluorescent part is rectangular, the fluorescent part receives excitation light from the excitation light source and emits fluorescence from six surfaces. At this time, it can be said that the fluorescence emitted from the facing surface of the fluorescent portion facing the light guide plate is likely to enter the light guide plate. However, the fluorescence emitted from the other five surfaces of the fluorescent part is less likely to enter the light guide plate because the fluorescent light isotropically emitted from the fluorescent part. Therefore, in the conventional light emitting device, it is difficult to say that the fluorescence emitted from the fluorescent part is efficiently guided to the light guide plate.

  On the other hand, in the light emitting device 1, the fluorescent part 10 is entirely disposed inside the light guide plate 3. Therefore, as described above, in the light emitting device 1, most of the fluorescence emitted from the fluorescent portion 10 disposed inside the light guide plate 3 is incident on the inside of the light guide plate 3 as it is, and the fluorescent portion 10 and the light guide plate 3. Loss of fluorescence between the two is reduced.

  Thus, there is a large difference in the proportion of fluorescence guided to the light guide plate between the light emitting device 1 and the conventional light emitting device.

  Furthermore, since the fluorescent part 10 is disposed inside the light guide plate 3, the distance between the fluorescent part 10 and the LED element 2 can be increased, so that the heat of the LED element 2 is less likely to be transmitted to the fluorescent part 10. Deterioration of the part 10 can be suppressed.

  Here, each of the light guide plate 3 and the fluorescent portion 10 is illustrated as a rectangle in FIG. 1, but is not limited to a specific shape. The same applies to the light emitting device 100 described later.

  In FIG. 1, the plurality of LED elements 2 are arranged in parallel with one side surface 3 a of the light guide plate 3 at a constant interval. However, the plurality of LED elements 2 need not be regularly arranged as shown in FIG. The same applies to the light emitting device 100 described later.

  In FIG. 1, the entire fluorescent portion 10 is disposed inside the light guide plate 3 and is disposed in parallel with one side surface 3 a of the light guide plate 3. However, the fluorescent part 10 does not need to be arranged in parallel with the one side surface 3 a of the light guide plate 3, and at least a part of the fluorescent part 10 only needs to be arranged inside the light guide plate 3. An example is shown in FIG. FIG. 2 is a schematic view of the light emitting device 50 in which a part of the fluorescent portion 10 is disposed inside the light guide plate 3 and the rest is disposed outside the light guide plate 3.

  As shown in the figure, in the fluorescent part 10, a part corresponding to the fluorescent part 10 a of the fluorescent part 10 is arranged inside the light guide plate 3, and a part corresponding to the fluorescent part 10 b of the fluorescent part 10 is outside the light guide plate 3. Placed in. At this time, most of the fluorescence emitted from the fluorescent portion 10 a disposed inside the light guide plate 3 is directly incident on the inside of the light guide plate 3. Thereby, compared with the case where all the fluorescence parts 10 are located outside the light guide plate 3, the ratio by which the light radiate | emitted from the fluorescence part 10 in the same direction is guided to the light guide plate 3 can be raised, As a result The luminous efficiency of the light emitting device 1 can be improved.

  FIG. 2 is an example of a light emitting device in which at least a part of the fluorescent portion 10 is disposed inside the light guide plate 3. Therefore, the present embodiment includes a configuration in which most of the fluorescent portion 10 is disposed inside the light guide plate 3 and a configuration in which a small portion of the fluorescent portion 10 is disposed inside the light guide plate 3. It is.

[Configuration of Light Emitting Device 100]
Next, the light emitting device 100 will be described with reference to FIG. FIG. 3 is a schematic diagram of the light emitting device 100. The light emitting device 100 includes a plurality of LED elements 2, a light guide plate 3, a fluorescent part 10, and a fluorescent part 11.

  The whole of the fluorescent part 10 and the fluorescent part 11 is arranged inside the light guide plate 3 and is arranged in parallel with one side surface 3 a of the light guide plate 3. Furthermore, the fluorescent part 11 is disposed at a position closer to the LED element 2 than the fluorescent part 10. The fluorescent part 10 and the fluorescent part 11 are arranged in contact with each other.

  The fluorescent part 11 is different from the fluorescent part 10 in the following points. Specifically, the fluorescent part 11 receives light emitted from the LED element 2 and emits fluorescence having a color different from that of the fluorescent part 10. Of the fluorescent part 10 and the fluorescent part 11, the fluorescent part 11 having a longer wavelength of emitted fluorescence is arranged at a position closer to the LED element 2 than the fluorescent part 10.

  Generally, the fluorescent part has a characteristic that it easily absorbs light having a shorter wavelength than the fluorescence emitted by itself. Therefore, in the light emitting device 100, the fluorescent part 10 and the fluorescent part 11 are arranged as described above, and the fluorescent part 10 absorbs the fluorescence emitted from the fluorescent part 11 arranged at a position close to the LED element 2. (Mutual absorption) is suppressed.

  Therefore, since the light emitting device 100 can efficiently use the fluorescence emitted from the fluorescent part 10 and the fluorescent part 11 while suppressing mutual absorption, the luminous efficiency can be further improved.

  Here, as an example of the light-emitting device 100, the fluorescent unit 10 receives blue light and emits green fluorescence, and the main wavelength of the light is 510 nm to 560 nm. The fluorescent part 11 receives blue light and emits red fluorescence, and the main wavelength of the light is 600 nm to 680 nm. That is, the wavelength of red fluorescence emitted from the fluorescent part 11 is longer than the wavelength of green fluorescence emitted from the fluorescent part 10.

  Therefore, by arranging the fluorescent part 11 closer to the LED element 2 than the fluorescent part 10, it is possible to suppress the green fluorescent light emitted from the fluorescent part 11 from being absorbed by the fluorescent part 10, and to emit light from the light emitting device. Efficiency can be further improved.

  Here, in FIG. 3, the fluorescent part 10 and the fluorescent part 11 are entirely disposed inside the light guide plate 3 and parallel to the one side surface 3 a of the light guide plate 3. However, the fluorescent part 10 and / or the fluorescent part 11 do not need to be arranged in parallel with the one side surface 3 a of the light guide plate 3, and at least a part of the fluorescent part 10 and / or the fluorescent part 11 may be arranged inside the light guide plate 3.

  In FIG. 3, the fluorescent part 10 and the fluorescent part 11 are arranged in contact with each other. However, the fluorescent part 10 and the fluorescent part 11 may be spaced apart from each other.

[Configuration of Light Emitting Device 150]
Next, the light emitting device 150 will be described with reference to FIG. FIG. 4 is a schematic diagram of the light emitting device 150. The light emitting device 150 includes a plurality of LED elements 2, a light guide plate 3, a fluorescent part 10, a fluorescent part 11, and a fluorescent part 12.

  The whole of the fluorescent part 10, the fluorescent part 11, and the fluorescent part 12 is arranged inside the light guide plate 3 and is arranged in parallel with one side surface 3 a of the light guide plate 3. Furthermore, the fluorescent part 10, the fluorescent part 11, and the fluorescent part 12 are arranged in the vicinity of the LED element 2 in order from the fluorescent part having a long wavelength of emitted fluorescence.

  The fluorescent part 12 is different from the fluorescent part 11 which is the same as the fluorescent part 10 in the following points. Specifically, the fluorescent part 12 receives the light emitted from the LED element 2 and emits fluorescence of a color different from that of the fluorescent part 10 and the fluorescent part 11.

  As described above, the fluorescent part has a characteristic that it easily absorbs light having a shorter wavelength than the fluorescence emitted by itself. Therefore, the light emitting device 150 can efficiently use the fluorescence emitted by each fluorescent part while suppressing the mutual absorption by arranging the fluorescent part 10, the fluorescent part 11, and the fluorescent part 12 as described above. Therefore, the luminous efficiency can be further increased.

  Here, as an example of the light-emitting device 150, the fluorescent unit 10 receives blue light and emits green fluorescence, and the main wavelength of the light is 510 nm to 560 nm. The fluorescent part 11 receives blue light and emits red fluorescence, and the main wavelength of the light is 600 nm to 680 nm. The fluorescent part 12 receives blue light and emits yellow fluorescence, and the main wavelength of the light is 560 nm to 590 nm.

  That is, the wavelength of red fluorescence emitted from the fluorescent part 11 is the longest, and the wavelength of green emitted from the fluorescent part 10 is the shortest. Therefore, the light emitting device 150 can suppress mutual absorption of light by arranging the fluorescent part 11, the fluorescent part 12, and the fluorescent part 10 in the order in a position close to the LED element 2. The luminous efficiency of 150 can be further increased.

  Here, in FIG. 4, the fluorescent part 10, the fluorescent part 11, and the fluorescent part 12 are all arranged inside the light guide plate 3 and parallel to one side surface 3 a of the light guide plate 3. However, the fluorescent part 10, the fluorescent part 11, and the fluorescent part 12 do not have to be arranged in parallel with the one side surface 3 a of the light guide plate 3, and at least a part of the fluorescent part 10, the fluorescent part 11, and the fluorescent part 12 may be arranged inside the light guide plate 3.

  In FIG. 4, the fluorescent part 10, the fluorescent part 11, and the fluorescent part 12 are arranged in contact with each other. However, the fluorescent part 10, the fluorescent part 11, and the fluorescent part 12 may be arranged apart from each other.

[Configuration of Light Emitting Device 200]
Next, the light emitting device 200 will be described with reference to FIG. FIG. 5 is a schematic diagram of the light emitting device 200. The light emitting device 200 includes a plurality of LED elements 2, a light guide plate 3, and a fluorescent part 10.

  The light emitting device 200 differs from the light emitting device 1 described with reference to FIG. 1 in the following points.

  Specifically, in the light emitting device 1, the fluorescent portion 10 is disposed inside the light guide plate 3, whereas in the light emitting device 200, one main surface of the fluorescent portion 10 is one side surface of the light guide plate 3. It arrange | positions so that 3a may be touched.

  Thereby, in the light emitting device 200, much of the fluorescence emitted from the fluorescent portion 10 disposed inside the light guide plate 3 can be directly incident on the inside of the light guide plate 3. Therefore, the light emitting device 200 can efficiently guide the light emitted from the fluorescent part 10 to the light guide plate 3, and can improve the light emission efficiency.

  Further, in the light emitting device 200, the fluorescent part 10 is arranged so that one main surface thereof is in contact with the one side surface 3 a of the light guide plate 3, so that the fluorescent part 10 and the fluorescent part 11 are guided when the light emitting device 200 is manufactured. Positioning into the optical plate 3 becomes extremely easy.

[Configuration of Light Emitting Device 300]
Next, the light emitting device 300 will be described with reference to FIG. FIG. 6 is a schematic view of the light emitting device 300. The light emitting device 300 includes a plurality of LED elements 2, a light guide plate 3, a fluorescent part 10, and a fluorescent part 11.

  The light emitting device 300 differs from the light emitting device 100 described with reference to FIG. 3 in the following points.

  Specifically, in the light emitting device 100, the fluorescent portion 10 and the fluorescent portion 11 are disposed inside the light guide plate 3, whereas in the light emitting device 300, the fluorescent portion 11 has one main surface on the light guide plate. 3 is in contact with one side surface 3a.

  Thereby, in the light emitting device 300, most of the fluorescence emitted from the fluorescent part 10 and the fluorescent part 11 disposed inside the light guide plate 3 can be directly incident on the inside of the light guide plate 3. Therefore, the light emitting device 300 can efficiently guide the light emitted from the fluorescent part 10 to the light guide plate 3 and improve the light emission efficiency.

  Moreover, the fluorescent part 11 with the longer wavelength of the emitted fluorescent light among the fluorescent part 10 and the fluorescent part 11 is arranged at a position closer to the LED element 2 than the fluorescent part 10. Thereby, the light-emitting device 300 suppresses that the fluorescence emitted by the fluorescent part 11 arranged at a position close to the LED element 2 is absorbed by the fluorescent part 10 (mutual absorption), and further increases the luminous efficiency. it can.

  Further, in the light emitting device 300, the fluorescent portion 11 is arranged so that one main surface thereof is in contact with the one side surface 3 a of the light guide plate 3, so that the fluorescent portion 10 and the fluorescent portion 11 are guided when the light emitting device 300 is manufactured. Positioning into the optical plate 3 becomes extremely easy.

  4, the light emitting device 150 described with reference to FIG. 4 may be arranged such that one main surface of the fluorescent portion 11 is in contact with one side surface 3a of the light guide plate 3, similarly to the light emitting device 300.

[Configuration of Light Emitting Device 400]
Next, the light emitting device 400 will be described with reference to FIG. FIG. 7 is a schematic diagram of the light emitting device 400. The light emitting device 400 includes a plurality of LED elements 2, a light guide plate 3, and a fluorescent part 15.

  The fluorescent portion 15 is formed in a semi-cylindrical shape, the curved surface side is disposed toward the inner side of the light guide plate 3, and the rectangular surface is disposed in contact with one side surface 3 a of the light guide plate 3. That is, in the fluorescent portion 15, the fluorescent emission surface facing the surface on which the light emitted from the LED element 2 is incident is formed in a convex shape in the direction in which the light is emitted from the LED element 2.

  In general, the light emitted from the fluorescent part is emitted in a direction perpendicular to the light emission surface. Accordingly, the light emitting device 400 uses the semi-cylindrical fluorescent portion 15 to increase the ratio of light guided to the inside of the light guide plate 3 (light extraction efficiency), and return light toward the LED element 2. Can be reduced, whereby the luminous efficiency can be further increased.

  In FIG. 7, the fluorescent portion 15 is disposed such that the rectangular surface is in contact with one side surface 3 a of the light guide plate 3, but all of the fluorescent portion 15 may be disposed inside the light guide plate 3.

  Here, instead of the semi-cylindrical fluorescent portion 15, a fluorescent portion of another shape can be used. This will be described with reference to FIG. FIG. 8 is a diagram for explaining a cross-sectional shape of the fluorescent part. In addition, the cross section of FIG. 8 shows the cross section which cut | disconnected the fluorescence part in the advancing direction of the light radiate | emitted from the LED element 2. FIG. In FIG. 8, the LED element 2 is sealed with a transparent resin formed in a cup shape, and here, the whole is referred to as the LED element 2.

  First, the fluorescent part 15 of FIG. 8A is the semi-cylindrical fluorescent part 15 of FIG. 7, and the fluorescent emission surface 15b opposite to the incident surface 15a on which the light emitted from the LED element 2 is incident is an LED. It is formed in a convex shape in the direction in which light is emitted from the element 2.

  In the fluorescent part 16 of FIG. 8B, the incident surface 16a on which the light emitted from the LED element 2 is incident and the fluorescent emission surface 16b opposite to the incident surface 16a are arranged in the direction in which the light is emitted from the LED element 2. It is formed in a convex shape. By curving the entrance surface 16a and the exit surface 16b, the ratio of light guided to the inside of the light guide plate 3 (light extraction efficiency) is increased, and the ratio of return light toward the LED element 2 is decreased. be able to.

  8C, the incident surface 17a on which the light emitted from the LED element 2 is incident is formed in a convex shape in the direction in which the light is emitted from the LED element 2. By making the incident surface 17a on the LED element 2 side into a curved structure, the ratio of return light in the direction of the LED element 2 can be reduced.

  The fluorescent portion 18 in FIG. 8D has a fluorescent emission surface constituted by reference numbers 18b, 18c, and 18d in the drawing facing the incident surface 18a on which the light emitted from the LED element 2 is incident. 2 is formed in a convex shape in the direction in which light is emitted.

  In the fluorescent part 19 of FIG. 8 (e), the incident surface 19a on which the light emitted from the LED element 2 is incident and the fluorescent emission surface 19b opposite to the incident surface 19a are in the direction in which the light is emitted from the LED element 2. It is formed in a convex shape.

  That is, in each fluorescent part in FIG. 8, at least one of the incident surface of the LED element 2 and the emitting surface facing the incident surface in the fluorescent part is convex toward the direction in which light is emitted from the LED element 2. Is formed. By forming the fluorescent part as shown in FIG. 8, the ratio of light guided to the inside of the light guide plate 3 (light extraction efficiency) is increased, and the ratio of return light toward the LED element 2 is decreased. Thus, the light emission efficiency of the light emitting device can be further increased.

  In addition, the shape of the fluorescent part shown in FIG. 8 is an example, Comprising: It is not limited to these shapes. Further, at least a part of the fluorescent part shown in FIG. 8 only needs to be arranged inside the light guide plate 3.

[Configuration of Light Emitting Device 500]
Next, a light emitting device 500 which is a modification of the present embodiment will be described with reference to FIG. FIG. 9 is a schematic diagram of the light emitting device 500. The light emitting device 500 includes a plurality of LED elements 2, a light guide plate 3, and a fluorescent part 20.

  The fluorescent part 20 is formed integrally with one side surface 3 a and the side surface 3 b of the light guide plate 3. For example, the fluorescent portion 20 is applied to the side surface 3a and the side surface 3b, or at least a part of the fluorescent portion 20 is placed inside the light guide plate 3 by forming the fluorescent portion 20 as a part of the side surface 3a and the side surface 3b. The arranged state is formed.

  As a result, in the light emitting device 500, most of the fluorescence emitted from the fluorescent part 20 enters the light guide plate 3 as it is. Thereby, the light-emitting device 500 can efficiently guide the light emitted from the fluorescent part 20 to the light guide plate 3, thereby improving the light emission efficiency.

  The various light emitting devices 1 and the like according to the present embodiment have been described above. Here, in the light emitting device 1 or the like, the fluorescent portion 10 or the like disposed in parallel with the side surface 3a along the one side surface 3a of the light guide plate 3 is used in the corresponding FIG. However, the fluorescent part may be provided so as to correspond to each of the plurality of LED elements 2 for each position facing the LED elements 2. Thereby, the usage-amount of a fluorescence part can be reduced and it can contribute to the cost reduction of a light-emitting device.

  Further, the fluorescent part 10 and the like according to the present embodiment includes a phosphor that emits fluorescence upon receiving the light of the LED element 2 and a sealing material that seals the phosphor, and includes a sealing material and a light guide plate 3. The material that constitutes can have the same refractive index or a smaller refractive index of the sealing material. Further, the same material may be used for the same refractive index.

In general, light hardly travels from a higher refractive index to a smaller refractive index, and light loss is likely to occur. On the other hand, light easily travels from the smaller refractive index to the larger refractive index, and light loss hardly occurs. Therefore, the light emitting device 1 and the like can easily make light emitted from the fluorescent part 10 and the like incident on the light guide plate 3 by setting the refractive index as described above, and can further increase the light emission efficiency.
[Other application examples]
The light emitting device 1 and the like can also be used as a light source for a backlight of a liquid crystal display device, which will be described with reference to FIG. FIG. 10 is a schematic diagram when the light emitting device 1 or the like is used as a backlight light source of the liquid crystal display device 40. Although the light emitting device 1 is described here, the light emitting device 100 described above may be used instead of the light emitting device 1.

  As illustrated, the display device 40 includes the light emitting device 1. The light emitting device 1 includes an LED element 2, a light guide plate 3, a circuit board 4, a substrate 5, and a fluorescent part 10.

  The substrate 5 has a plurality of LED elements 2 mounted on the surface thereof. The substrate 5 has a circuit board 4 and electrodes (not shown) connected to the circuit board 4 on the surface thereof.

  In the display device 40, the light emitting device 1 is used as a light source for the backlight unit. Fluorescence emitted from the fluorescent portion 10 that has entered the light guide plate 3 is sent to the exit surface of the light guide plate 3 by total reflection, scattering, or the like inside the light guide plate 3. In the display device 40, the size of the light guide plate 3 is appropriately adjusted so that light having uniform characteristics reaches the side surface portion of the light guide plate 3.

  In addition, the incidence of light from the LED element 2 to the fluorescent unit 10 and the light guide plate 3 may be performed from all directions such as both sides and four sides of the display device 40, and is not limited to the configuration illustrated in FIG.

  Here, the fluorescent part used in the display device 40 may include a nanoparticle fluorescent material. As described above, even when a nanoparticle phosphor uses a material having the same composition, the emission color can be changed by the quantum size effect by changing the particle diameter of the material to a nanometer size.

Therefore, the use of the nanoparticle phosphor facilitates the wavelength control of the light emitted from the light guide unit 3 and facilitates matching with the transmittance characteristics of the color filter. Therefore, by using the nanoparticle phosphor, the display on the display device 40 can be brightened, and the color can be changed, so that the effect of improving the color reproducibility can be expected.
[Other Examples of LED]
Next, various types of LED elements 2 will be described with reference to FIGS.

  FIG. 11 is a cross-sectional view of the LED element 2a. The plurality of LED elements 2 a are each sealed with a transparent resin formed in a cup shape and mounted on the substrate 5.

  FIG. 12 is a cross-sectional view of the LED element 2b. The plurality of LED elements 2b are sealed together in a transparent resin and arranged at intervals. The plurality of LED elements 2 b are mounted on the substrate 5.

Thus, various types of LED elements can be used in the light emitting device 1 and the like according to the present embodiment. This is the same even if the excitation light source is a laser or the like, and various types of excitation light sources can be used.
[Another expression of this embodiment]
The light emitting device according to this embodiment can also be expressed as follows.

  The light-emitting device according to the present embodiment includes an excitation light source that emits excitation light, a main surface and side surfaces, a light guide plate that emits light incident from the side surfaces via the main surface, and the excitation light source. A light emitting unit that emits fluorescence in response to the emitted excitation light, and the light emitting unit is provided inside the light guide plate.

  In addition, the light emitting device according to the present embodiment may have a configuration in which a part of the light emitting unit is disposed on a side surface of the light guide plate.

  In the light emitting device according to the present embodiment, the light emitting unit receives light from the excitation light source and emits red fluorescence, and the light from the excitation light source emits green fluorescence. The first light emitting unit and the second light emitting unit may be arranged in that order from the excitation light source in the optical axis direction of the excitation light.

  In addition, the light emitting device according to the present embodiment may have a configuration in which the light emitting unit has a semi-cylindrical shape.

  In the light emitting device according to the present embodiment, the light emitting unit may include a nanoparticle phosphor.

  Moreover, the light-emitting device which concerns on this Embodiment may be the structure which the material which comprises the said light emission part and the said light-guide plate is the same material.

  In addition, the display device according to the present embodiment may be configured to include any of the light emitting devices described above.

  Heretofore, various forms of the light emitting device according to this embodiment have been described. These forms show an example of the present embodiment, and it is naturally possible to combine the forms described here.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  The present invention can be suitably applied to a display device using a light emitting device that efficiently guides light emitted from a fluorescent portion to a light guide plate.

1, 50, 100, 150, 200, 300, 400, 500 Light-emitting device 2 LED element (excitation light source)
DESCRIPTION OF SYMBOLS 3 Light guide plate 4 Circuit board 5 Substrate 10-12, 15-20 Fluorescence part 40 Display apparatus

Claims (10)

A fluorescent part that emits fluorescence in response to excitation light emitted from an excitation light source;
A light guide plate for guiding the fluorescence emitted from the fluorescent part,
At least a part of the fluorescent part is disposed inside the light guide plate.   The light emitting device according to claim 1, wherein the entire fluorescent portion is disposed inside the light guide plate. The fluorescent part comprises at least a first fluorescent part and a second fluorescent part,
The first fluorescent part emits fluorescence in response to excitation light emitted from the excitation light source,
The second fluorescent part receives excitation light emitted from the excitation light source and emits fluorescence of a color different from that of the first fluorescent part,
The fluorescent part having a longer wavelength of the emitted fluorescence of the first fluorescent part and the second fluorescent part is disposed at a position closer to the excitation light source than the other fluorescent part. 3. The light emitting device according to 1 or 2. The first fluorescent part receives light from a blue light emitting element and emits red fluorescence,
4. The light emitting device according to claim 3, wherein the second fluorescent part emits green fluorescent light upon receiving light from a blue light emitting element. The fluorescent part includes a phosphor that emits fluorescence upon receiving the excitation light, and a sealing material that seals the phosphor,
5. The material according to claim 1, wherein the sealing material and the material constituting the light guide plate have the same refractive index, or the sealing material has a smaller refractive index. Light emitting device.   At least one of the incident surface of the excitation light and the exit surface of the fluorescent portion facing the incident surface in the fluorescent portion is formed in a convex shape in a direction in which the excitation light is emitted from the excitation light source. The light-emitting device according to claim 1, wherein the light-emitting device is a light-emitting device.   The light-emitting device according to claim 1, wherein the fluorescent part includes a nanoparticle fluorescent material. A third fluorescent part that receives excitation light emitted from the excitation light source and emits fluorescence of a color different from that of the first fluorescent part and the second fluorescent part;
The said 1st fluorescence part, the said 2nd fluorescence part, and the said 3rd fluorescence part are arrange | positioned near the said excitation light source in order from the fluorescence part with long wavelength of the emitted fluorescence. The light-emitting device of description. The first fluorescent part receives light from a blue light emitting element and emits red fluorescence,
The second fluorescent part receives light from the blue light emitting element and emits green fluorescence.
The third fluorescent part emits yellow fluorescent light upon receiving light from the blue light emitting element,
The light emitting device according to claim 8, wherein the first fluorescent part, the third fluorescent part, and the second fluorescent part are arranged in the order in a position close to the excitation light source.   A display device comprising the light-emitting device according to claim 1.

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