JP5444919B2 - Illumination device and liquid crystal display device - Google Patents

Description

  The present invention relates to a lighting device and a liquid crystal display device. In particular, the present invention relates to an illumination device using a light emitting diode as a light source, and a liquid crystal display device.

  In recent years, a liquid crystal display (LCD) has been widely used as a display device used for a television receiver, a personal computer (hereinafter, PC), a mobile phone, a portable information terminal, a portable game machine, and the like. It is becoming. Usually, a liquid crystal display device is provided with a transmissive liquid crystal display panel having a color filter, and a backlight device that illuminates the liquid crystal display panel from the back side. In the liquid crystal display device, light emitted from the backlight device is irradiated onto the liquid crystal display panel, and light selectively transmitted by the liquid crystal display panel is output as an image. For example, a cold cathode fluorescent lamp (CCFL) or a light emitting diode (LED) is used as a light source of the backlight device.

  In particular, a light-emitting diode is useful as a light source for a backlight device because of its low power consumption and high color reproducibility. When a light emitting diode is used as the light source of the backlight device, three types of light emitting diodes corresponding to the three primary colors of light, red, green, and blue, are used in combination. That is, the liquid crystal display panel is irradiated with white light generated by mixing red light, green light, and blue light emitted from three types of light emitting diodes. When a light emitting diode is used, white light with high color purity can be obtained, so that the color reproduction range of output light can be greatly expanded compared to the case of using CCFL. In addition, since the output of the light emitting diode is relatively high, the luminance of the backlight device can be increased by using a high output light emitting diode.

  However, since each light emitting diode is a point light source, unevenness in brightness and color may occur in the light that is transmitted through the liquid crystal display panel and output. For example, luminance unevenness and color unevenness occur in a situation where the light emitting diode is disposed directly below the liquid crystal display panel so that light emitted from the light emitting diode is incident on the liquid crystal display panel vertically. In order to suppress the occurrence of such luminance unevenness and color unevenness, for example, in Patent Document 1 below, light is emitted by an optical resin mixed with a diffusion material in order to diffuse light emitted directly above the light emitting diode. A configuration for covering the upper surface of the diode is described.

JP 2006-286906 A

  However, when the thickness of the liquid crystal display device is reduced, it is not sufficient to simply diffuse the illumination light in the upward direction, and it is required to uniformly diffuse the diffused light to the periphery immediately above. If the optical distance is defined as the distance between the substrate on which the light emitting diode is placed and the opposite surface of the liquid crystal display panel, the light emitted in the same direction reaches the liquid crystal display panel as the optical distance becomes sufficiently short. The average stroke is shortened. Therefore, a region where light emitted from a plurality of adjacent light emitting diodes is mixed becomes narrow. That is, in order to efficiently extract white light with high color purity, it is useful to narrow down the region where the three primary colors are mixed while extending the above average process. Therefore, it is required to increase the extraction efficiency while controlling the emission direction and diffusion direction of the light emitted from the light emitting diodes of each color light to suppress the occurrence of luminance unevenness and color unevenness.

  A technique for adjusting the color tone of the light source is described in, for example, Japanese Patent Application Laid-Open No. 2000-208815. The technique described in this document is to provide a resin containing a phosphor immediately above a light emitting diode, and include them with a resin containing a diffusing material. Thus, by providing the resin containing the phosphor, the color tone of the light source can be adjusted. However, since the light-emitting diode package described in the document directly reflects the light distribution characteristic of the light-emitting diode, the light distribution characteristic cannot be arbitrarily controlled on the resin side. Japanese Patent Application Laid-Open No. 11-31845 proposes a package structure for improving the light distribution characteristics. However, even if the package structure described in the same document is applied, a sufficient intensity of light is emitted laterally. Difficult to distribute light.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to suppress uneven luminance and uneven color even when the optical distance is short, and to irradiate uniform light. It is another object of the present invention to provide a new and improved lighting device and liquid crystal display device.

  In order to solve the above-described problem, according to an aspect of the present invention, a light source installed on a substrate, a first optical resin formed so as to cover an upper portion of the light source and kneaded with a fluorescent material, Provided is a lighting device comprising: a second optical resin formed to cover an upper portion of the first optical resin; and a third optical resin formed on the upper portion of the second optical resin and kneaded with a light diffusing substance. Is done.

  In addition, the lighting device described above has a maximum length of the third optical resin relative to the maximum length of the second optical resin, with respect to the maximum length connecting the outer edges of the cross section obtained by cutting the substrate surface in a plane. The maximum length of the third optical resin may be smaller than the maximum length of the first optical resin.

  The second optical resin may be formed so as to enclose the light source and the first optical resin.

  In the illumination device, the amount of the fluorescent material kneaded with the first optical resin is adjusted so that a predetermined color tone is obtained.

  Moreover, in said illuminating device, the quantity of the said scattering material kneaded with said 3rd optical resin or the height of said 3rd optical resin is adjusted so that predetermined | prescribed luminance distribution may be obtained.

  The refractive index of the first optical resin is preferably larger than the refractive index of the second optical resin. Furthermore, the refractive index of the second optical resin is preferably larger than the refractive index of the third optical resin.

  In order to solve the above problems, according to another aspect of the present invention, there is provided a liquid crystal display panel and a backlight device provided with a plurality of illumination devices for illuminating the liquid crystal display panel from the back. Each of the lighting devices is formed so as to cover a light source installed on a substrate, an upper part of the light source, a first optical resin kneaded with a fluorescent material, and an upper part of the first optical resin. There is provided a liquid crystal display device comprising: the formed second optical resin; and a third optical resin formed on the second optical resin and kneaded with a light diffusion material.

  As described above, according to the present invention, even when the optical distance is short, uneven brightness and uneven color can be suppressed and uniform light can be irradiated.

It is explanatory drawing which shows the structure of the liquid crystal display panel which concerns on one Embodiment of this invention. It is explanatory drawing which shows the structure of the backlight apparatus which concerns on one Embodiment of this invention. It is explanatory drawing which shows the cross-section of the liquid crystal display device which concerns on one Embodiment of this invention. It is explanatory drawing which shows the circuit structural example of the liquid crystal display device which concerns on one Embodiment of this invention. It is explanatory drawing which shows the structure of the light emitting diode apparatus which concerns on one Embodiment of this invention. It is explanatory drawing which shows the structure of the light emitting diode apparatus which concerns on one Embodiment of this invention. It is explanatory drawing which shows the structure of the light emitting diode apparatus which concerns on one Embodiment of this invention. It is explanatory drawing which shows the light distribution characteristic of the light emitting diode mounted in the light emitting diode apparatus which concerns on one Embodiment of this invention. It is explanatory drawing which shows the light distribution characteristic of the light emitting diode apparatus which concerns on one Embodiment of this invention. It is explanatory drawing which shows the relationship between the preparation ratio of the fluorescent substance mixed in the resin material for forming the light emitting diode apparatus which concerns on one Embodiment of this invention, and luminescent color. It is explanatory drawing which shows the resin height dependence of the light distribution characteristic of the light emitting diode device which concerns on one Embodiment of this invention, and the peak value which appears in the said light distribution characteristic.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

<Embodiment>
Hereinafter, an embodiment of the present invention will be described. The technology according to the present embodiment relates to a backlight light source mounted on a thin liquid crystal display device, and more particularly to a liquid crystal display device using a light emitting diode as a backlight light source. Further, the technology according to the present embodiment relates to a technology for irradiating a panel with uniform light while suppressing luminance unevenness and color unevenness even in a thin liquid crystal display device having a short optical distance. Hereinafter, the liquid crystal display device 100 according to the present embodiment will be described. In particular, the configuration, formation method, and the like of the light-emitting diode device 184 and the like mounted on the liquid crystal display device 100 will be sequentially described with specific examples.

(Description item)
1: Structure of the liquid crystal display device 100 (FIGS. 1 to 4)
2: About the structure of the light emitting diode device 184 (FIGS. 5 to 7)
3: Light distribution characteristics of the light-emitting diode device 184 (FIGS. 8 to 11)
4: Summary

[1: Structure of liquid crystal display device 100 (FIGS. 1 to 4)]
The structure of the liquid crystal display device 100 according to the present embodiment will be described. First, the structure of the liquid crystal display panel 110 mounted on the liquid crystal display device 100 will be described with reference to FIG. Next, the structure of the backlight device 150 mounted on the liquid crystal display device 100 will be described with reference to FIG. Next, the structure of the liquid crystal display device 100 including the liquid crystal display panel 110 and the backlight device 150 will be described with reference to FIG. Next, a configuration example of a drive circuit mounted on the liquid crystal display device 100 will be described with reference to FIG.

  As described above, the liquid crystal display device 100 includes the liquid crystal display panel 110 and the backlight device 150. The backlight device 150 is provided on the back side of the liquid crystal display panel 110. The liquid crystal display device 100 may include a terrestrial broadcast reception tuner, a satellite wave broadcast reception tuner, or the like. Further, the liquid crystal display device 100 may include a signal processing unit that performs predetermined signal processing on the video signal and the audio signal received by these reception tuners. And the liquid crystal display device 100 may be equipped with the audio | voice output part for outputting the audio | voice signal output from the signal processing part.

(About the structure of the liquid crystal display panel 110)
As shown in FIG. 1, the liquid crystal display panel 110 has two transparent substrates (TFT substrate 114 and counter electrode substrate 112) formed of glass or the like. In addition, a liquid crystal layer 116 is formed in the gap between the TFT substrate 114 and the counter electrode substrate 112 that are arranged to face each other. For example, twisted nematic (TN) liquid crystal is sealed in the liquid crystal layer 116.

  A plurality of signal lines 124 and scanning lines 126 are arranged in a matrix on the TFT substrate 114. A pixel electrode 130 and a thin film transistor 132 are formed at the intersection of the signal line 124 and the scanning line 126. However, it should be noted that the detailed configurations of the pixel electrode 130 and the thin film transistor 132 are not clearly shown in FIG. The thin film transistor 132 is a switching element corresponding to each pixel. The thin film transistor 132 is selected by a scanning signal flowing through the scanning line 126. When a pixel is selected by the scanning signal, the thin film transistor 132 corresponding to the pixel writes the video signal supplied from the signal line 124 to the pixel electrode 130 corresponding to the pixel.

  In the counter electrode substrate 112, a counter electrode 128 and a color filter 122 are formed on the surface facing the TFT substrate 114. The color filter 122 is divided into a plurality of segments corresponding to each pixel. Further, the color filter 122 is divided into a red filter R, a green filter G, and a blue filter B corresponding to the three primary colors red, green, and blue. Examples of the arrangement pattern of the color filter 122 include a stripe arrangement pattern, a delta arrangement pattern, and a square arrangement pattern.

  The liquid crystal display panel 110 includes two polarizing plates 118 and 120. The polarizing plates 118 and 120 are arranged so as to sandwich a laminated structure formed by the counter electrode substrate 112, the liquid crystal layer 116, and the TFT substrate 114. Therefore, white light emitted by the backlight device 150 described later enters the TFT substrate 114 through the polarizing plate 120, and sequentially passes through the liquid crystal layer 116, the counter electrode substrate 112, and the polarizing plate 118. At this time, the liquid crystal display panel 110 is driven by an active matrix method, so that a full color image is displayed.

  The structure of the liquid crystal display panel 110 has been briefly described above with reference to FIG. Next, the backlight device 150 will be described with reference to FIG.

(About the structure of the backlight device 150)
As shown in FIG. 2, the backlight device 150 includes a casing 152, a diffusion plate 154, a diffusion sheet 156, a prism sheet 158, and a polarization conversion sheet 160. However, the structure of the casing 152 will be described later. Further, the diffusion sheet 156, the prism sheet 158, and the polarization conversion sheet 160 may be collectively referred to as an optical function sheet group.

  As described above, the backlight device 150 illuminates the liquid crystal display panel 110 from the back side. The casing unit 152 has light sources of each color inside. Further, the diffusion plate 154, the diffusion sheet 156, the prism sheet 158, and the polarization conversion sheet 160 are provided in order to mix the light emitted from the light sources of the respective colors provided in the housing unit 152. The diffusion sheet 156 is placed on the diffusion plate 154. The prism sheet 158 is placed on the diffusion sheet 156. The polarization conversion sheet 160 is placed on the prism sheet 158.

  The diffusion plate 154 diffuses the light emitted from the casing unit 152 inside. Therefore, the provision of the diffusion plate 154 makes it possible to make the luminance uniform in surface light emission. The optical function sheet group includes, for example, a function of decomposing incident light into two orthogonal polarization components, a function of compensating for a phase difference of light waves to achieve a wide-angle viewing angle and preventing coloring, a function of diffusing incident light, and a brightness improvement. It has a function to plan. That is, the optical function sheet group converts the optical characteristics of light emitted from the casing 152 into optical characteristics suitable for illumination of the liquid crystal display panel 110. Therefore, if such a conversion function is realized, the present invention is not limited to the configuration of the optical function sheet group shown in FIG.

  The structure of the backlight device 150 has been briefly described above with reference to FIG. Here, the description of the configuration of the casing unit 152 will be supplemented.

  Three types of light emitting diodes that respectively emit red light, green light, and blue light are provided in the housing portion 152. For example, light emitted from a red light emitting diode has a wavelength of about 640 nm. The light emitted from the green light emitting diode has a wavelength of about 530 nm. The light emitted from the blue light emitting diode has a wavelength of about 450 nm.

  However, adjustment to widen the color gamut by shifting the peak wavelength of the light emitted from the red light emitting diode to the long wavelength side or shifting the peak wavelength of the light emitted from the blue light emitting diode to the short wavelength side. May be given. By performing such color gamut adjustment, the color reproduction range of an image displayed on the liquid crystal display panel 110 can be expanded. Moreover, in order to improve the utilization efficiency of the light emitted from each light emitting diode, the inner wall surface of the housing 152 may be subjected to reflection processing.

  Heretofore, a supplementary explanation has been given briefly regarding the configuration of the casing 152. Next, the internal structure of the casing 152 and the overall structure of the liquid crystal display device 100 will be described with reference to FIG.

(About the structure of the liquid crystal display device 100)
As shown in FIG. 3, the liquid crystal display device 100 is mainly composed of the liquid crystal display panel 110 shown in FIG. 1 and the backlight device 150 shown in FIG. Further, the liquid crystal display panel 110 and a part of the backlight device 150 are fixed using a guide member 172, an outer frame 174, an inner frame 176, an inner wall surface 178, and a bracket member 180.

  The external frame 174 constitutes an external housing of the liquid crystal display device 100. An inner frame 176 is provided inside the outer frame 174. The liquid crystal display panel 110 is fixed so as to be sandwiched between the outer frame 174 and the inner frame 176. A spacer is sandwiched between the polarizing plate 118 and the external frame 174 of the liquid crystal display panel 110. A spacer is sandwiched between the polarizing plate 120 and the internal frame 176 of the liquid crystal display panel 110. Further, a guide member 172 is provided in a space surrounded by the inner frame 176, the outer frame 174, and the liquid crystal display panel 110. The guide member 172 is provided to prevent the liquid crystal display panel 110 from being displaced in the direction of the external frame 174 (−X direction).

  On the other hand, the optical function sheet group and the diffusion plate 154 forming the backlight device 150 are fixed so as to be sandwiched between the bracket member 180 provided on the inner wall surface 178 and the inner frame 176. A spacer is sandwiched between the polarization conversion sheet 160 forming the optical function sheet group and the internal frame 176. The bracket member 180 fixes the diffusion plate 154 so as to support the bottom surface (end surface in the −Z direction) of the diffusion plate 154. A substrate 186 is placed on the inner wall surface 178 corresponding to the frame of the housing portion 152. In addition, a reflective sheet 182 and a light emitting diode device 184 are placed on the substrate 186.

  The reflection sheet 182 is installed such that the reflection surface faces the bottom surface of the diffusion plate 154. Further, the reflection sheet 182 is installed at a position lower than the light emitting portion of the light emitting diode device 184 (close to the −Z direction). With such a configuration, the reflection sheet 182 can reflect the light emitted downward from the light emitting diode device 184 or the light reflected by the inner wall surface 178 to be incident on the diffusion plate 154. For the reflection sheet 182, for example, a reflection film formed by sequentially laminating a silver reflection film, a low refractive index film, and a high refractive index film on a sheet base material is used. The inner wall surface 178 may be mirror-finished so as to reflect light, similarly to the reflection sheet 182.

  The overall structure of the liquid crystal display device 100 has been briefly described above with reference to FIG. As described above, the liquid crystal display device 100 is provided with the light emitting diode device 184. The light emitted from the light emitting diode device 184 is incident on the liquid crystal display panel 110 through the diffusion plate 154 and the optical function sheet group. As already described, the present embodiment relates to the configuration and formation method of the light emitting diode device 184. The configuration and the like of the light emitting diode device 184 according to the present embodiment will be described in detail later, but before that, the configuration of the drive circuit mounted on the liquid crystal display device 100 will be described with reference to FIG.

(About the configuration of the drive circuit)
For example, a drive circuit as shown in FIG. 4 is mounted on the liquid crystal display device 100. The drive circuit includes an input terminal 10, an RGB process processing unit 12, a control unit 14, a user interface 16, a backlight drive unit 18, a power source 20, an image memory 22, an X driver 24, and a Y driver. And a driver 26.

  The power source 20 supplies driving power to the liquid crystal display panel 110 and the backlight device 150. The X driver 24 and the Y driver 26 drive the liquid crystal display panel 110. The backlight drive unit 18 drives and controls the backlight device 150. A video signal supplied from the outside or a video signal processed by a video signal processing unit (not shown) is input to the input terminal 10. The video signal input from the input terminal 10 is input to the RGB process processing unit 12. A control unit 14 and an image memory 22 are connected to the RGB process processing unit 12.

  The RGB process processing unit 12 performs signal processing such as chroma processing on the input video signal. Further, the RGB process processing unit 12 converts the composite signal into an RGB separate signal suitable for driving the liquid crystal display panel 110. The RGB separate signal output from the RGB process processing unit 12 is input to the control unit 14 and also input to the X driver 24 via the image memory 22. The control unit 14 drives the X driver 24 and the Y driver 26 at a predetermined timing according to the RGB separate signal. As described above, the liquid crystal display panel 110 is driven and controlled by the X driver 24 and the Y driver 26 based on the RGB separate signals. As a result, an image corresponding to the RGB separate signal is output to the liquid crystal display panel 110.

  The backlight driver 18 receives power from the power supply 20 and generates a pulse width modulation (PWM) signal. And the backlight drive part 18 makes each light emitting diode apparatus 184 which is a light source of the backlight apparatus 150 light-emit based on a pulse width modulation signal. The color temperature of the light emitting diode depends on the operating current. Therefore, in order to maintain the color reproducibility faithfully (maintaining the color temperature constant) while maintaining a luminance of a predetermined level or higher, the amount of current supplied to the light emitting diode device 184 is controlled based on the pulse width modulation signal. By using the pulse width modulation signal in this way, it is possible to suppress color temperature change and maintain color reproducibility while maintaining desired luminance.

  The user interface 16 is an operation input unit used for selecting a video signal reception channel and adjusting an audio output amount. The user interface 16 is used for adjusting the brightness of the backlight device 150, adjusting the white balance, and the like. For example, when luminance adjustment is performed using the user interface 16, the control unit 14 inputs a luminance control signal corresponding to a user operation to the backlight driving unit 18. Further, the backlight driving unit 18 controls the light emitting diode device 184 of each color by adjusting the duty ratio of the pulse width modulation signal for each color according to the input luminance control signal.

  The configuration of the drive circuit mounted on the liquid crystal display device 100 has been briefly described above. Hereinafter, the light emitting diode device 184 according to the present embodiment will be described in detail.

[2: Structure of light-emitting diode device 184 (FIGS. 5 to 7)]
The light emitting diode device 184 according to this embodiment will be described. First, the structure of the light-emitting diode device 184 will be described with reference to FIGS.

  As shown in FIG. 5, the light emitting diode device 184 includes a light emitting diode 192, a first optical resin 194, a second optical resin 196, and a third optical resin 198.

  The light emitting diode 192 is formed on the substrate 186. Although not clearly shown in the drawing, the light emitting diode 192 includes a buffer layer, a first cladding layer, an active layer, a second cladding layer, a cap layer, and the like formed on the substrate 186. These layers are formed by, for example, a crystal growth method. Further, although not explicitly shown in the figure, the wiring of the light emitting diode 192 is connected to the electrode by wire bonding or the like. The light emitting diode 192 is driven by electric power supplied from the connected electrodes.

  A first optical resin 194 is formed on the light emitting diode 192 so as to cover at least the top surface (light emitting surface) of the light emitting diode 192. The first optical resin 194 is kneaded with a fluorescent material for adjusting the color tone. Therefore, when the first optical resin 194 is irradiated with light having a predetermined wavelength emitted from the light emitting diode 192, the fluorescent material contained in the first optical resin 194 is excited, and light having a wavelength different from the predetermined wavelength is emitted. Is done. At this time, the fluorescent material transitions to a high excited state by light of a predetermined wavelength, and then transitions to a low excited state or a ground state with light radiation. That is, light having an energy difference between states is emitted.

  For example, assume that the light emitting diode 192 is a blue light source. At this time, if the fluorescent material that emits green light and red light with respect to the incident blue light is kneaded in the first optical resin 194, when the blue light is irradiated from the light emitting diode 192 to the first optical resin 194, The first optical resin 194 emits light in which green light and red light are mixed. Of course, since the blue light emitted from the light emitting diode 192 is also mixed, the light emitted from the first optical resin 194 becomes white light to human eyes if each color light is mixed with an appropriate intensity. I can feel it. Note that the color tone can be arbitrarily adjusted by changing the blending ratio of the fluorescent substance and the kneading amount (see FIG. 10). In addition, as a fluorescent substance, an yttrium aluminum garnet (YAG) fluorescent substance etc. can be used, for example.

  The first optical resin 194 also plays a role of protecting the light emitting diode 192. Therefore, as shown in FIG. 5, the first optical resin 194 is preferably formed so as to cover the light emitting diode 192. Further, the first optical resin 194 is formed inside the second optical resin 196. The second optical resin 196 forms a lens that is emitted from the light emitting diode 192 and improves the extraction efficiency of the light Li whose color tone is adjusted by the first optical resin 194. The second optical resin 196 also serves to protect the light emitting diode 192 and the first optical resin 194. The first optical resin 194 and the second optical resin 196 are made of, for example, silicone.

  A third optical resin 198 is formed on the second optical resin 196. The material of the third optical resin 198 is, for example, a material in which the diffusing material particles are kneaded in the same material as the second optical resin 196 in a weight ratio of about 30% to about 80%. Therefore, the light emitted from the light emitting diode 192 and transmitted through the first optical resin 194 and the second optical resin 196 is scattered by the diffusing material particles kneaded in the third optical resin 198. The diffusing material particles preferably have a diameter of about 3 μm to 12 μm. Further, the shape of the diffusing material particles is preferably substantially spherical.

  As shown in FIG. 5, the first optical resin 194 forming the light emitting diode device 184 has a substantially hemispherical shape that covers the entire light emitting diode 192. Further, the second optical resin 196 forming the light emitting diode device 184 has a substantially hemispherical shape so as to cover the entire first optical resin 194. That is, the first optical resin 194 and the second optical resin 196 have a dome shape formed on the XY plane and rising in the Z direction. Further, the first optical resin 194 and the second optical resin 196 are formed such that the top of the head and the light emission center of the light emitting diode 192 are aligned on the same axis (center axis C).

  The height of the second optical resin 196 along the Z direction is L1. Further, the third optical resin 198 is formed on the upper surface of the second optical resin 196. The third optical resin 198 has a height L2 along the Z direction. The height L2 has a relationship L1 = (0.5 to 3.0) * L2 with the height L1 of the second optical resin 196. In particular, the height L2 is preferably larger than the height L1 and about three times at most. The third optical resin 198 is a dome shape that rises in the Z direction with the upper surface (including the top of the head) of the second optical resin 196 as the bottom surface. Further, the third optical resin 198 is formed so that the central axis (or the top of the head) is located on the central axis C.

  The maximum diameter of the third optical resin 198 in the XY cross section is smaller than the maximum diameter of the second optical resin 196 in the XY cross section. That is, it can be said that the third optical resin 198 has a columnar shape that is substantially symmetrical with respect to rotation in the XY plane with the central axis C as an axis. The maximum diameter of the third optical resin 198 is preferably the same as or larger than the maximum diameter of the first optical resin 194.

  Now, the light Li emitted from the light emitting diode 192 enters the third optical resin 198 through the first optical resin 194 and the second optical resin 196. However, since the second optical resin 196 is provided, not all the light emitted from the light emitting diode 192 is incident on the third optical resin 198. That is, a part of the light emitted from the light emitting diode 192 is radiated directly from the surface of the second optical resin 196 to the internal space of the housing portion 152. On the other hand, the incident light Li incident on the third optical resin 198 is scattered by the diffusing material kneaded in the third optical resin 198 and is scattered light Ls from the surface of the third optical resin 198 to the internal space of the housing portion 152. To be emitted.

  As described above, since the diffusing material is mixed in the third optical resin 198, the incident light Li is scattered by the diffusing material particles and emitted at an angle different from the Z direction. As already described, in the present embodiment, the color tone of light emitted from the light emitting diode 192 via the first optical resin 194 can be arbitrarily adjusted, and the light emitted from the light emitting diode 192 is efficient. In addition, the object is to ensure uniform mixing. As described above, the purpose of making it possible to arbitrarily adjust the color tone is realized by providing the first optical resin 194 kneaded with the fluorescent material and adjusting the blending ratio of the fluorescent material and the kneading amount.

  On the other hand, for the purpose of efficiently and uniformly mixing the light emitted through the first optical resin 194, the orbit of the light emitted from the light emitting diode 192 in the Z direction is separated from the Z direction (Z direction and It is necessary to make a large change toward the direction in which the angle formed by is large. Thus, in order to change the light trajectory greatly, the scattering cross section of the third optical resin 198 may be increased. Therefore, in the present embodiment, the third optical resin 198 has a shape extending in the Z direction. By adopting such a shape, the travel of light traveling in the Z direction in the third optical resin 198 is extended, and the scattering cross section of light traveling in the Z direction is increased.

  However, the third optical resin 198 is formed so that the diameter (radius) of the XY cross section is shortened. By adopting such a shape, it is possible to shorten the stroke until the scattered light Ls scattered inside the third optical resin 198 reaches the surface of the third optical resin 198. Therefore, the scattered light Ls scattered in the direction away from the Z direction is radiated to the internal space of the casing 152 relatively easily. As a result, the luminance of light emitted in the Z direction is relatively small, and the luminance of light emitted in a direction away from the Z direction is relatively large.

  Further, the third optical resin 198 is formed not to cover the entire top surface of the second optical resin 196 but to cover only the vicinity immediately above (Z direction). By adopting such a structure, the intensity loss due to scattering is reduced by the amount of light extracted directly from the surface of the second optical resin 196. As described above, by efficiently scattering only the light Li emitted in the vicinity of the light emitting diode 192 (in the Z direction), luminance unevenness can be suppressed while maintaining sufficient extraction efficiency.

  Here, the refractive indexes of the first optical resin 194, the second optical resin 196, and the third optical resin 198 will be described. As described above, in the light emitting diode device 184, the light emitting diode 192, the first optical resin 194, the second optical resin 196, and the third optical resin 198 are sequentially stacked on the substrate 186. At this time, in order to improve the extraction efficiency of the light emitted by the light emitting diode 192, it is preferable to set the refractive index to decrease as the distance from the light emitting diode 192 increases. For example, based on the refractive index 1 of air, the refractive index of the first optical resin 194 is approximately 1.6 to 1.8, and the refractive index of the second optical resin 196 is approximately (1.6 to 1.8 + 1). It is preferable to set the refractive index of the third optical resin 108 to about 1 and to about / 2. With this setting, the light extraction efficiency can be improved.

  Next, referring to FIG. 6, the XY cross-sectional shape of the light-emitting diode device 184 will be confirmed. In particular, the mutual relationship regarding the dimensions of the first optical resin 194, the second optical resin 196, and the third optical resin 198 is clearly shown. However, the cross-sectional shape illustrated in FIG. 6 is not necessarily required as long as the effects obtained by the structural features illustrated in FIG. 5 are realized. In the example of FIG. 6, the cross-sectional shape is circular, but it may be, for example, an arbitrary substantially elliptical shape or a substantially rectangular shape.

  FIG. 6 schematically shows the XY cross-sectional shape of the first optical resin 194, the second optical resin 196, and the third optical resin 198 and the XY cross-sectional shape of the light-emitting diode 192 in the maximum diameter portion. Has been. The maximum diameter of the first optical resin 194 is expressed as d1, the maximum diameter of the second optical resin 196 is expressed as d2, and the maximum diameter of the third optical resin 198 is expressed as d3. The diagonal length of the light emitting diode 192 is denoted as K.

  First, the relationship between the maximum diameter d1 of the first optical resin 194 and the diagonal length K of the light emitting diode 192, the maximum diameter d1 of the first optical resin 194, the maximum diameter d2 of the second optical resin 196, and the first The relationship between the maximum diameter d3 of the three optical resins 198 will be described.

  As described above, the first optical resin 194 is formed so as to cover the light emitting diode 192. Therefore, the maximum diameter d1 of the first optical resin 194 has a relationship of d1> K with the diagonal length K of the light emitting diode 192. With such a relationship, the light emitting diode 192 can be protected by the first optical resin 194.

  Further, the first optical resin 194 is formed inside the second optical resin 196. Therefore, the maximum diameter d1 of the first optical resin 194 has a relationship of d2> d1 with the maximum diameter d2 of the second optical resin 196. With this relationship, the first optical resin 194 can be protected by the second optical resin 196.

  Further, the maximum diameter d1 of the first optical resin 194 has a relationship of d1 ≦ d3 with the maximum diameter d3 of the third optical resin 198. With this relationship, light whose color tone is adjusted by the first optical resin 194 is diffused by the third optical resin 198 without leakage. As a result, the light whose color tone is adjusted by the first optical resin 194 is sufficiently mixed, and the color tone of the light emitted from the light emitting diode device 184 is further uniformized.

  Next, the relationship between the maximum diameter d2 of the second optical resin 196 and the maximum diameter d3 of the third optical resin 198 will be described. The maximum diameter d3 of the third optical resin 198 is set to about 1 to 4 times the diagonal length K of the light emitting diode 192.

  The maximum diameter d2 of the second optical resin 196 has a relationship of d2> d3 with the maximum diameter d3 of the third optical resin 198. With this structure, part of the light emitted in the direction away from the Z direction is directly extracted from the surface of the second optical resin 196. In this way, by directly extracting light emitted at a relatively large angle, it is possible to avoid intensity loss due to scattering by that amount. In other words, by efficiently scattering only the light emitted immediately above the light emitting diode 192 (in the Z direction), it is possible to suppress luminance unevenness while maintaining sufficient extraction efficiency.

  The structure of the light emitting diode device 184 has been described above. FIG. 7 shows a photograph taken when the light emitting diode device 184 schematically shown in FIGS. As described above, the light emitting diode device 184 shown in FIG. 7 is provided with the first optical resin 194 so as to cover at least the top surface of the light emitting diode 192, and the second optical resin 196 so as to cover the first optical resin 194. The third optical resin 198 is provided in the vicinity of the top of the second optical resin 196. With such a structure, a light emitting diode device 184 (LED package) having excellent light distribution characteristics and capable of arbitrarily adjusting the color tone is realized.

[3: Regarding Light Distribution Characteristics of Light-Emitting Diode Device 184 (FIGS. 8 to 11)]
Next, the light distribution characteristics of the light-emitting diode device 184 will be described with reference to FIGS. FIG. 8 is an explanatory diagram showing the light distribution characteristics of the light emitting diode 192. FIG. 9 is an explanatory diagram showing the light distribution characteristics of the light-emitting diode device 184. First, the light distribution characteristics of the light emitting diode 192 will be described with reference to FIG. Next, the light distribution characteristics of the light-emitting diode device 184 will be described while comparing FIG. 8 and FIG.

  First, referring to FIG. FIG. 8 shows a luminance ratio distribution (light distribution characteristic) based on the luminance observed at a position where the light distribution angle (see FIG. 11B) is 0 °. However, the light distribution characteristic illustrated in FIG. 8 is emitted from the light emitting diode 192 without providing the third optical resin 198, and all the light transmitted through the first optical resin 194 is emitted from the surface of the second optical resin 196. Is the case. The light distribution characteristic shown in FIG. 8 has a peak at a light distribution angle of 0 °, and is expressed by an upward convex curve such that the luminance ratio decreases as the absolute value of the light distribution angle increases. FIG. 8 shows the light distribution characteristics of the light-emitting diode 192 observed under three different conditions, all of which show the same tendency.

  Due to the lens effect of the second optical resin 196, a certain level of luminance is obtained even at a light distribution angle having a large absolute value. However, the luminance decreases as the absolute value of the light distribution angle increases. As described above, when the luminance is concentrated in the Z direction, the mixing probability of the light emitted from the plurality of light emitting diodes 192 is lowered, so that high purity white light cannot be obtained. Further, the color light of each light emitting diode 192 is irradiated to the liquid crystal display panel 110, and color unevenness or the like occurs. In order to suppress such color unevenness and the like, it is necessary to efficiently diffuse light irradiated in a direction with a small light distribution angle and increase the amount of light irradiated in a direction with a large light distribution angle.

  In the present embodiment, as a mechanism for efficiently diffusing light, the installation of a third optical resin 198 having a structure as shown in FIGS. 5 and 6 is proposed. By providing the third optical resin 198, the luminance ratio graph showing the light distribution characteristics changes to a shape as shown in FIG.

  FIG. 9 shows the light distribution characteristic obtained by the light emitting diode device 184 provided with the third optical resin 198. However, it is noted that light refracted in a direction where the light distribution angle is sufficiently large due to the lens effect of the second optical resin 196 is emitted from the surface of the second optical resin 196 without passing through the third optical resin 198. I want. As shown in FIG. 9, the luminance ratio of the light emitted in the direction with a large light distribution angle is increased by the effect of installing the third optical resin 198.

  In the example of FIG. 9, the peak of the luminance ratio appears when the absolute value of the light distribution angle is around 70 °. Further, the peak value of the luminance ratio exceeds 2.5. That is, 2.5 times the luminance is observed as compared with the luminance of the light emitted directly above the light emitting diode 192. In the light emitting diode device 184 according to this embodiment, the light distribution angle and the peak value at which the peak of the luminance ratio appears can be adjusted by changing the dimension of the third optical resin 198 (see FIG. 11). The light emitted in the minus direction is reflected by the reflection sheet 182 and the like immediately below the light emitting diode device 184 and mixed with the light emitted in the plus direction.

  The configuration of the light emitting diode device 184 according to the present embodiment and the light distribution characteristics obtained by the light emitting diode device 184 have been described above. As shown in FIG. 10, the color tone of light emitted from the light emitting diode device 184 can be arbitrarily adjusted by adjusting the blending ratio of the fluorescent material to be kneaded into the first optical resin 194 and the kneading amount. . In addition, as shown in FIG. 11, by changing the dimensions of the third optical resin 198, it is possible to arbitrarily adjust the light distribution characteristics of the light emitted from the light emitting diode device 184. The light distribution characteristics can also be adjusted by adjusting the amount of the scattering material kneaded in the third optical resin 198.

  As described above, when the light distribution characteristics can be arbitrarily adjusted, it is possible to reduce the thickness of the backlight device 150 directly under the LED used in the liquid crystal display device 100. Further, by adjusting to a suitable light distribution characteristic, it is possible to reduce the number of LEDs to be installed in the backlight device 150 of the direct type LED used in the liquid crystal display device 100. Further, when the light emitting diode device 184 described above is used for LED illumination, it is possible to irradiate the illumination range uniformly, so that a lens normally provided in the light source can be omitted.

[4: Summary]
The technical contents of the present embodiment described above can be summarized as follows by extracting the characteristic portions.

  The light emitting diode device 184 is an example of a lighting device having the following configuration. The lighting device is formed so as to cover a light source installed on a substrate, an upper portion of the light source, a first optical resin kneaded with a fluorescent material, and an upper portion of the first optical resin. A second optical resin and a third optical resin formed on the second optical resin and kneaded with a light diffusion material. As described above, the fluorescent material is kneaded in the first optical resin, so that the color tone of the light transmitted through the first optical resin is adjusted to a predetermined color tone. That is, the color tone of the transmitted light can be adjusted by adjusting the amount of the fluorescent material kneaded in the first optical resin.

  The light transmitted through the first optical resin is transmitted through the second optical resin that functions as a lens and then enters the third optical resin. Since the light scattering material is kneaded in the third optical resin, incident light is scattered inside the third optical resin. Therefore, the light emitted from the light source is scattered in the vertical direction of the substrate and the angle direction close thereto, and is emitted at an angle close to the horizontal direction of the substrate. As a result, when the above-described illumination device is used as the backlight of the liquid crystal display device 100, it is possible to suppress the occurrence of color unevenness, luminance unevenness, and the like, while the above-described illumination device is used as LED illumination. When is used, it is not necessary to provide a lens for uniformly irradiating light.

  In addition, the lighting device described above has a maximum length of the third optical resin relative to the maximum length of the second optical resin, with respect to the maximum length connecting the outer edges of the cross section obtained by cutting the substrate surface in a plane. It is preferable that the length is smaller and the maximum length of the third optical resin is equal to or less than the maximum length of the first optical resin. In this way, by making the outer dimension of the second optical resin larger than the outer dimension of the third optical resin, the light refracted by the second optical resin at an angle close to the horizontal direction of the substrate is transmitted to the third optical resin. It becomes possible to inject without passing resin. For this reason, the luminance is improved by the amount of light emitted without being affected by the attenuation due to scattering. Also, by making the outer dimension of the third optical resin larger than the outer dimension of the first optical resin, the color tone is adjusted, and most of the light emitted in the direction perpendicular to the substrate can be scattered without omission. become.

  The refractive index of the first optical resin is preferably larger than the refractive index of the second optical resin. The refractive index of the second optical resin is preferably larger than the refractive index of the third optical resin. As described above, the optical resin provided at a position farther from the light source is configured to have a higher refractive index, thereby increasing the light extraction efficiency.

(Remarks)
The light emitting diode 192 is an example of a light source. The light emitting diode device 184 is an example of a lighting device.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

DESCRIPTION OF SYMBOLS 10 Input terminal 12 RGB process processing part 14 Control part 16 User interface 18 Backlight drive part 20 Power supply 22 Image memory 24 X driver 26 Y driver 100 Liquid crystal display device 110 Liquid crystal display panel 112 Counter electrode board | substrate 114 TFT board | substrate 116 Liquid crystal layer 118, DESCRIPTION OF SYMBOLS 120 Polarizing plate 122 Color filter 124 Signal line 126 Scan line 128 Counter electrode 130 Pixel electrode 132 Thin film transistor 150 Backlight device 152 Case part 154 Diffusion plate 156 Diffusion sheet 158 Prism sheet 160 Polarization conversion sheet 172 Guide member 174 External frame 176 Internal frame 178 Inner wall surface 180 Bracket member 182 Reflective sheet 184 Light emitting diode device 186 Substrate 192 Light emitting diode 194 First optical resin 96 second optical resin 198 third optical resin

Claims (6)

A light source installed on the substrate;
A first optical resin formed so as to cover an upper portion of the light source and kneaded with a fluorescent material;
A second optical resin formed to cover an upper portion of the first optical resin;
A third optical resin formed on the second optical resin and kneaded with a light diffusing substance;
Equipped with a,
Regarding the maximum length connecting the outer edges of the cross section obtained by cutting the substrate surface along a horizontal plane, the maximum length of the third optical resin is smaller than the maximum length of the second optical resin, and the first The maximum length of the three optical resins is not less than the maximum length of the first optical resin;
The lighting device , wherein a height of the third optical resin is larger than a height of the second optical resin . The lighting device according to claim 1 , wherein the second optical resin is formed so as to include the light source and the first optical resin. The lighting device according to claim 2 , wherein an amount of the fluorescent material kneaded in the first optical resin is adjusted so that a predetermined color tone is obtained. The lighting device according to claim 3 , wherein an amount of the light diffusing substance kneaded in the third optical resin or a height of the third optical resin is adjusted so that a predetermined luminance distribution is obtained. The refractive index of the first optical resin is larger than the refractive index of the second optical resin,
The lighting device according to claim 4 , wherein a refractive index of the second optical resin is larger than a refractive index of the third optical resin. A liquid crystal display panel, and a backlight device provided with a plurality of illumination devices for illuminating the liquid crystal display panel from the back;
Each of the lighting devices is
A light source installed on the substrate;
A first optical resin formed so as to cover an upper portion of the light source and kneaded with a fluorescent material;
A second optical resin formed to cover an upper portion of the first optical resin;
A third optical resin formed on the second optical resin and kneaded with a light diffusing substance;
Equipped with a,
Regarding the maximum length connecting the outer edges of the cross section obtained by cutting the substrate surface along a horizontal plane, the maximum length of the third optical resin is smaller than the maximum length of the second optical resin, and the first The maximum length of the three optical resins is not less than the maximum length of the first optical resin;
The height of the third optical resin is a liquid crystal display device larger than the height of the second optical resin .