JP2005183139A - Lighting system and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein an ideal white display cannot be obtained unless optical matching with a liquid crystal display element because the characteristics of a fluorescence material used for wavelength conversion greatly affect the color characteristics since a spectrum of an illumination light is determined by a blue light source, green light obtained by performing wavelength conversion of the blue light and an emission spectrum of a red light source for color mixture. <P>SOLUTION: This liquid crystal lighting system uses a first light source emitting single blue light and a second light source emitting single red light, and is provided with a white light source which obtaining white light by the additive mixture of colors mixing the blue light of the first light source, the green light generated by wavelength conversion of the single blue light and the red light of the second light source and a color correction means by subtractive color mixture in somewhere between the display screen of the liquid crystal display element, for example, at least one of between an incidence plane of a light guide plate and the light sources and between an exposure surface of the light guide plate and the liquid crystal display elements. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an illumination device used as a light source of a color liquid crystal display element, and a liquid crystal display device using the illumination device.

  Liquid crystal display devices used in mobile phones, portable small TVs, portable game machines, PDAs, small notebook personal computers, etc. have good lighting characteristics and low heat generation and noise instead of cold cathode tubes. Lighting devices using LEDs (Light-Emitting-Diodes) as light sources have come to be frequently used.

  In general, in a transmissive color liquid crystal display device, an illumination device using a white light source is used as a backlight to illuminate a liquid crystal display element provided with R (Red) G (Green) B (Blue) color filters in each pixel. As a result, a color image is displayed. However, various devices have been made because there is no LED capable of emitting ideal white light.

  For example, a method of illuminating a liquid crystal display device by realizing a pseudo-white light source with little coloring by arranging three light sources of red LED, green LED, and blue LED in close proximity, and making the white light obtained therefrom enter a light guide plate. It is known (see, for example, Patent Document 1).

  The second typical method is to excite a phosphor with blue light emitted from a blue LED to obtain light in a band from green light to red light by wavelength conversion, and this green light, red light and blue light. Are mixed to obtain pseudo white light, which is led to a light guide plate to illuminate the liquid crystal display device. In this method, compared with the method using the three LEDs described above, the number of necessary LEDs is reduced to 1/3, so that the power consumption is remarkably reduced. At the same time, the three LED outputs are finely adjusted to obtain a pseudo white color. No need for color shifts.

  The third typical method is to obtain the red light from the green light by wavelength conversion by exciting the phosphor with the blue light emitted from the blue LED formed with the phosphor, and the light obtained by this wavelength conversion. There is a method of obtaining pseudo-white light by additively mixing blue light and blue light, and at the same time, by adding additional red color to this pseudo-white light to improve red saturation, thereby obtaining white light close to ideal ( For example, see Patent Document 2). By using this method, it is possible to easily obtain near-ideal white light simply by adjusting the output of the red LED, thereby realizing a liquid crystal display device capable of clearer color display.

Further, in order to efficiently mix pseudo white light and red light without color shift, a blue LED and a red LED on which a phosphor is formed are arranged close to each other in a transparent resin mold having a lens function (for example, , Refer to Patent Document 3), by arranging the first LED and the second LED formed with phosphors at both ends of the light pipe, respectively, pseudo white light and red light can be uniformly mixed in the light pipe. There is a known method (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 10-247411 (page 4, FIG. 1) JP 2000-275636 A (page 2-3) JP 2002-57376 A

  Conventionally, a blue LED having an emission wavelength of 450 nm is used to excite green light by a phosphor, and a liquid crystal display element is illuminated using an emission spectrum obtained by additive color mixing with the original blue light. Explain the case. FIG. 4 shows an example of an emission spectrum obtained from the first LED on which the phosphor is thus formed. That is, it is a graph showing an example of an emission spectrum obtained by exciting green light with a phosphor using a blue LED having an emission wavelength of 450 nm and performing additive color mixing with the original blue light. In this case, an emission spectrum peak of the first LED appears at 450 nm, and a spectrum peak of green light obtained by wavelength conversion of blue light with a phosphor appears at 550 nm. Further, as is clear from FIG. 4, the emission spectrum shows not only blue light and green light but also an emission spectrum from yellow to red although it is weak. Thus, the emission spectrum obtained using the phosphor that converts the wavelength of blue light into green light on the exit surface covers the entire visible light region, and as a result, it looks like white light in a pseudo manner. However, in order to adjust the whiteness, it is necessary to adjust the current flowing through the first blue LED to change the light emission luminance or to optimize the material of the phosphor, which cannot be easily performed.

  Further, in the color liquid crystal display device described in Patent Document 3 that can obtain light closer to white light, the first LED that emits blue monochromatic light and the second LED that emits red monochromatic light. A white color by additive color mixing that mixes blue light emitted from the first LED, green light generated by wavelength conversion from blue monochromatic light, and red light emitted from the second LED. Getting light. That is, white light is obtained from the blue light of the first LED and the pseudo white light obtained by the light generated by wavelength conversion from the blue monochromatic light and the red light of the second LED. In such a white light source, in order to efficiently mix pseudo white light and red light without color deviation, the first blue LED and the second red LED on which the phosphor is formed are made of a transparent resin having a lens function. Arrangements are made to mix pseudo white light and red light uniformly in the light pipe by arranging them close to each other in the mold, or by arranging blue LEDs and red light LEDs at both ends of the light pipe. ing.

  FIG. 5 shows an emission spectrum obtained by additively mixing red light with pseudo white light in this way. That is, FIG. 5 shows a case where green light is excited by a phosphor using a blue LED having an emission wavelength of 450 nm, and red light having a wavelength of 650 nm is additively mixed with pseudo white light obtained by additive color mixing with the original blue light. It is a graph which shows the obtained emission spectrum. The emission spectrum shown in FIG. 5 has an emission peak of red light at 650 nm because red light is superimposed on the pseudo white light shown in FIG. This red light is additively mixed with pseudo-white light to make up for the red component that was lacking, resulting in near-ideal white light and improving the red saturation of the color image as described later. Can be made.

  Even in such a configuration, the spectrum of the illumination light is determined by the respective emission spectra of the excitation blue LED, the green light and the red light obtained by wavelength-converting the blue light, and the color mixing red LED. . For this reason, the characteristics of the fluorescent material used greatly affect the color characteristics. Furthermore, since the light that has actually been seen is transmitted through a colored member such as a color filter of a color liquid crystal display element, an ideal white display can be obtained unless the illumination light and the color filter are optically matched. It has a problem that it cannot be obtained.

  Specifically, since the emission spectrum of the illumination light and the spectral distribution of the spectral transmittance characteristics of the color filter material do not match, in the color liquid crystal display device of Patent Document 3, the white display is slightly yellowish to orange. There was a problem.

  Therefore, in order to obtain an ideal white display by the color liquid crystal display device, the emission spectrum of each of the excitation blue LED, the mixed color red LED, and the green light obtained by converting the wavelength of the blue light is adjusted ( That is, the emission spectrum of illumination light is adjusted), the transmission spectrum of a colored member such as a color filter is adjusted, or both. However, such adjustment is time consuming and expensive because the material itself must be improved.

  Furthermore, the characteristics of the color filter used in the liquid crystal display element are usually different for each manufacturer and product, and an illumination device that can easily match the display color to such a liquid crystal display element is provided. There is also a problem that it is difficult to realize.

  Each pixel of the liquid crystal display element is formed with a color filter containing a dye or a pigment with a predetermined film thickness so as to selectively transmit a specific wavelength band corresponding to R, G, and B. FIG. 6 shows an example of spectral transmittance of a color filter corresponding to RGB used in the color liquid crystal element. The spectral transmittance of this color filter is determined by strictly designing it according to the color of the light source, the operation mode of the liquid crystal to be used, etc., and adjusting the type and density of the pigment or dye contained therein. Furthermore, since this color filter is formed inside the liquid crystal display element, it is designed with attention to not only optical characteristics but also electric characteristics. The spectral transmittance of the color filter is an important factor that determines the color reproducibility of the liquid crystal display element as well as the light source color.

  FIG. 7 shows a luminance spectrum of white display that can be displayed by the liquid crystal display device using the pseudo white light source having the emission spectrum shown in FIG. 4 and the display element having the color filter having the spectral transmittance shown in FIG. Since this luminance spectrum reflects the transmission characteristics of the color filter, green to blue near 500 nm and yellow to orange near 600 nm are emphasized compared to the emission spectrum of pseudo white light shown in FIG. The red component remains weak because the intensity contained in the pseudo white light itself is small. Therefore, the white color displayed with the pseudo white light source obtained in this way is changed from blue to greenish blue, and at the same time, sufficient red saturation is not obtained.

  Since the color filter performs color adjustment by subtractive color mixing, the easiest way to improve the color balance is to reduce the transmittance of the BG filter to achieve balance. However, since the color filter is formed on the pixel electrode, it directly affects the driving characteristics of the liquid crystal, and there are limitations on the film thickness that can be formed and the materials that can be selected. Further, adjusting the color balance by lowering the transmittance of the BG filter is not a preferable method because it significantly reduces the efficiency of use of illumination light.

  On the other hand, FIG. 8 shows a white luminance spectrum that can be displayed when a liquid crystal device using the white light source having the emission spectrum shown in FIG. 5 and the light emitting element having the color filter having the spectral transmittance shown in FIG. Show. The luminance spectrum shown in FIG. 8 has a markedly improved spectral intensity with respect to red light compared to the luminance spectrum shown in FIG. 7. As a result, the color rendering property for red is improved and a vivid red color can be expressed. At the same time, the white level is improved. However, similarly to the results obtained in FIG. 7, the luminance spectrum shown in FIG. 8 reflects the transmission characteristics of the color filter, so that the green-blue color near 500 nm and the wavelength near 600 nm are compared with the emission spectrum shown in FIG. It can be seen that the yellow to orange color is emphasized.

  Since the visual characteristics of human colors are particularly sensitive, it is easy to notice that this white image is colored just by slightly mixing yellow to orange or green-blue in this way. . As a result, the color image obtained is less vivid and the image quality is degraded.

  The liquid crystal lighting device of the present invention uses a first light source that emits blue monochromatic light and a second LED that emits red monochromatic light, and converts the blue light from the first light source and wavelength conversion from the blue monochromatic light. A white light source that obtains white light by additive color mixing that mixes the green light generated by the red light from the second light source, and the white light from the white light source is guided to be uniform on the display surface of the liquid crystal display element And a light correction plate that irradiates the liquid crystal display device, and includes a color correction means by subtractive color mixing somewhere before the white light from the white light source reaches the liquid crystal display element.

  With such a configuration, the color characteristics of the liquid crystal display element and the spectral distribution of the illumination light can be easily matched by a simple method, which is more ideal than yellow to orange coloring compared to conventional liquid crystal illumination devices. White light can be realized. In addition, by applying to a color liquid crystal display element, a color image with higher saturation can be reproduced. Furthermore, according to this configuration, since color characteristics can be easily matched simply by changing the color correction means, color matching can be easily performed for various color liquid crystal display elements having different characteristics. Can do.

  In particular, the color correction means is a polymer film having a function of absorbing or reflecting light in a predetermined wavelength region at a predetermined ratio, and is provided on at least one of the incident end surface of the light guide plate or the irradiation surface to the liquid crystal display element. Insertion or adhesive bonding does not impair the function of being small and thin.

  Furthermore, as the color correction means, a first polymer film having a function of absorbing or reflecting light in the first wavelength region at a predetermined ratio is used, and as the second color correction means, in the second wavelength region. By using the second polymer film having a function of absorbing or reflecting light at a predetermined ratio, more complex spectrum adjustment of illumination light can be performed. As a result, more ideal white light can be realized. Further, these color correction films can be superposed on each other and adhesively bonded to the incident end face or the irradiation face of the light guide plate.

  In addition, the polymer film used for color correction means is a mixture of pigment or dye that absorbs light of a predetermined wavelength at a predetermined concentration, thereby improving the spectrum of illumination light at a lower cost. White light can be obtained.

  As a color correction means, a loss due to absorption of light that occurs during spectrum adjustment of illumination light by using a polymer film on the surface of which an optical multilayer film for reflecting light of a predetermined wavelength at a predetermined ratio is used. Thus, a white illumination light source with high light use efficiency can be obtained.

  According to the configuration of the present invention, as the color correction means, a color correction film formed by adding a pigment or a dye to the base material or forming an optical multilayer film on the surface is used. Therefore, it is possible to provide a white light source having a good color balance easily without having to improve the color reproducibility of the liquid crystal display element.

  In addition, by using the liquid crystal lighting device having the structure of the present invention as described above, the color correction film can be exchanged for various color liquid crystal elements adopting color filters having various spectral transmittance characteristics. As a result, the color balance can be easily matched in a short time, so that the liquid crystal element can be easily designed and the product development delivery time can be shortened.

  The liquid crystal display device and the illumination device of the present invention have a configuration in which color correction means including a predetermined pigment or dye is provided in a part of the optical path from the white light source to the color liquid crystal element. As a result, it is possible to perform color correction by subtractive color mixture without affecting the driving characteristics of the color liquid crystal element, and the color reproducibility of the color liquid crystal element is improved.

  A basic configuration of the liquid crystal display device of the present invention will be described with reference to FIGS. FIG. 1 shows a configuration in which a color correction plate 3 as color correction means is provided between a light guide plate 2 and a color liquid crystal element 4. FIG. 2 shows a configuration in which the color correction means 3 is disposed between the white light source 1 and the light guide plate 2. FIG. 3 shows a configuration in which color correction means 3a and 3b are provided between the white light source 1 and the light guide plate 2 and between the light guide plate 2 and the color liquid crystal element 4, respectively. Here, the light guide plate 2 has a function of irradiating the color liquid crystal element 4 with light incident from the white light source 1.

The color correction plate 3 has a structure in which a substance that absorbs light of 570 to 610 nm, which is a wavelength band corresponding to yellow to orange, is contained in a transparent substrate. When this is used after being adhesively bonded to the light guide plate 2, it is formed by applying an adhesive to the surface of the substrate. The material to be contained must be appropriately selected according to the wavelength region to be absorbed. Further, since the concentration of the content is largely related to the thickness of the color correction plate, it is determined according to the thickness of the base material and the intended absorption strength.

  Embodiments of a liquid crystal display device according to the present invention will be described below with reference to the drawings. The basic structure of the liquid crystal display device of the present invention is schematically shown in FIGS.

  In the illuminating device of the present invention, subtractive color mixing is performed on a white image illuminated with a white light source using monochromatic light of a blue LED, green light generated by wavelength conversion of the blue LED, and monochromatic light of a red LED. By correcting with the correction means, white light was realized with quality that is not visually problematic. In the following examples, a color correction film containing a predetermined pigment or dye is used as a color correction means by this subtractive color mixture. This color correction film is formed in a part of the optical path from the white light source to the color liquid crystal element. Inserted. With such a configuration, color correction by subtractive color mixing can be performed without affecting the driving characteristics of the color liquid crystal element 4. Although a method of directly overlaying a color correction film containing a predetermined dye or pigment on the color filter formed on the pixel of the color liquid crystal element is also conceivable, this method may greatly affect the liquid crystal drive characteristics. Therefore, it is preferable to arrange a color correction film.

  In the embodiment shown in FIG. 1, the color correction film 3 is inserted between the irradiation end face of the light guide plate 2 and the color liquid crystal element 4, and in the embodiment shown in FIG. In the embodiment shown in FIG. 3, the color correction films (3a, 3b) are disposed between the light source 1 and the incident end surface of the side surface of the light guide plate, and the irradiated end surface of the light guide plate 2. It is inserted between both of the color liquid crystal elements 4.

  In the configuration of the embodiment of FIG. 1, the insertion accuracy of the color correction film 3 hardly affects the optical system most easily, and the size becomes suitable for handling, so that the handling becomes easy. However, since there is a possibility that the spectral characteristic unevenness and distribution in the plane of the color correction film 3 may be affected, it is desirable to sufficiently control the spectral characteristic unevenness and distribution.

  In addition, in the configuration of the embodiment of FIG. 2, it is difficult to influence the spectral characteristic unevenness and the distribution in the plane, but it is desirable that the color correction film 3 be very small so that it should be handled with great care.

  Further, in the configuration of the embodiment of FIG. 3, when two color correction films 3a and 3b are inserted, flexibility is improved with respect to controllability of optical characteristics.

  As a method of arranging the color correction film, the color correction films 3, 3 a, 3 b and the light guide plate 2 may be adhesively bonded by applying an adhesive on the color correction film, or a holding frame not shown Thus, a color correction film may be mechanically sandwiched between the light guide plate 2 and the light source 1 or the color liquid crystal element 4. In the configuration in which the color correction films 3, 3 a, 3 b and the light guide plate 2 are adhesively bonded, the color correction film is less likely to be scratched and damaged by surrounding elements due to vibration or impact during transportation. It is possible to reduce the reflectance on the adhesively bonded surfaces, and there is an advantage that the light use efficiency is improved. However, in this case, care must be taken because bubbles may cause uneven illumination if bubbles enter the adhesive part.

  Further, the color correction film 3 inserted between the light guide plate 2 and the color liquid crystal element 4 may be adhesively bonded to the surface of the color liquid crystal element 4.

  As the structure of the color correction film 3, a transparent polymer film such as polyethylene (PET) or polycarbonate (PC) is used as a base material, and light of 570 to 610 nm, which is a wavelength band corresponding to yellow to orange, is inside. In the case of using a material containing an absorbing pigment or dye, which is adhesively bonded to the light guide plate 2, it can be formed by applying an adhesive to the surface of the substrate. The material of the pigment or dye to be contained must be appropriately selected according to the wavelength region to be absorbed. Further, since the concentration of the content is largely related to the thickness of the color correction film, it is determined according to the film thickness and the intended absorption strength.

  When only one type is used as the dye, in many cases, the complementary color of the color developed by the dye becomes the absorption wavelength band. Therefore, it is preferable to use a plurality of dyes in the base material in order to control the wavelength band, the absorption intensity, and the like.

As another structure of the color correction film 3, an optical multilayer film in which a high refractive index material such as titanium oxide or zirconium oxide and a low refractive index material such as silicon dioxide or magnesium fluoride are alternately laminated is PET or PC. And formed on the surface of a transparent polymer film. When this is used after being adhesively bonded to the light guide plate 2, an adhesive is applied to the surface of the base material on which the optical multilayer film is not formed. Further, when the refractive indexes of the high refractive index material and the low refractive index material are n _H and n _L , and two appropriately selected wavelengths are λ ₁ and λ ₂ , a high refractive index having a film thickness of λ ₁ / 4n _H A multilayer film (M is a natural number) obtained by alternately stacking M pairs of materials and low refractive index materials having a film thickness of λ ₁ / 4n _L, a high refractive index material having a film thickness of λ ₂ / 4n _H , and a film thickness of λ ₂ / 4n _L And a multilayer film in which N pairs of low refractive index materials are alternately stacked (N is a natural number). These multilayer films can be formed by a vacuum deposition method or an ion plating method. The spectral characteristics of the color correction film having such a configuration can be easily determined by selecting a high refractive index material and a low refractive index material, determining the number of laminated layers M and N, and selecting the selection wavelengths λ ₁ and λ _2. it can.

  FIG. 9 shows the spectral transmittance of a color correction film obtained by incorporating a blue dye that absorbs yellow into a PET film having a thickness of 50 μm. This color correction film exhibits maximum absorption at a peak wavelength of 590 nm. When the color liquid crystal film having the spectral transmittance shown in FIG. 9 and the light source having the emission spectrum shown in FIG. 5 are combined with the display device having the configuration shown in FIG. 1, a white image is displayed on the color liquid crystal device. The luminance spectrum is as shown in FIG. As is clear from comparison between FIG. 8 and FIG. 10, the intensity of yellow to orange from 570 to 610 nm is reduced, and the luminance spectrum is corrected without reducing the intensity of blue light, green light, and red light. As a result, it was found that a better white image can be expressed with a slight bluish tint. This result can be reproduced even if the color correction filter is inserted into the arrangement of any of the embodiments shown in FIGS. 1, 2, and 3 as the insertion positions of the color correction films 3, 3a, and 3b. However, the film thickness of the two color correction films 3a and 3b inserted in the arrangement shown in FIG. 3 was set to 25 μm, which is 1/2 of the other cases.

  The following embodiment is an embodiment for eliminating a slight bluish color remaining in the white image obtained in FIG. Therefore, in addition to the color correction film used in the embodiment of FIG. 10, a color correction film having a spectral transmittance shown in FIG. 11 was prepared by incorporating an orange dye into a 50 μm thick PET film. The spectral transmittance of this color correction film has a small absorption peak at a wavelength of 500 nm. The color correction film having the spectral transmittance shown in FIG. 10 is used as the color correction film 3a on the light source side of the liquid crystal lighting device shown in FIG. 3, and the color transmission film 3b on the color liquid crystal element side is shown in FIG. A color correction film having a rate was used. In this way, the luminance spectrum of the white image displayed on the color liquid crystal element 4 is as shown in FIG. 12, and the white image that is slightly bluish in one color correction film is red light, green light, blue light. It was possible to obtain an ideal white image without affecting the contribution of.

  In the example shown in FIG. 12, two types of color correction films are inserted at the two positions shown in the embodiment shown in FIG. 3, but these two types of color correction films are arranged in an overlapping manner. Therefore, it goes without saying that the present invention can also be applied to the configuration shown in FIGS.

Further, a specific configuration of the lighting device of the present invention will be described.
FIG. 13 is an assembled perspective view schematically showing an embodiment of the illumination device of the present invention. As shown in the figure, a color correction film 10 is provided on the exit surface side of the light guide plate 11, and a first reflector 12 is provided on the back side. Further, the pseudo white LED 14 a and the red LED 14 b are connected to the flexible substrate 15, and light is incident on the light pipe 16. A second reflector 17 is provided behind the light pipe 16 so that incident light does not leak from other than the irradiated surface. These components are provided in the support frame 13.

  The pseudo white light LED 14a and the red LED 14b are directly mounted on the flexible substrate 15 provided with wiring. Here, the pseudo white light LED 14a is a phosphor formed on the emission surface of the blue light LED, and the blue light emitted from the blue light LED is wavelength-converted to generate green light and red light to generate pseudo white light. It means an LED that can emit light. The emission surfaces of the pseudo white light LED 14a and the red LED 14b are opposed to each other, and the pseudo white light and the red light emitted from these LEDs are guided through the light pipe 16 from both end faces of the light pipe 16 and guided. The light is emitted from the emission end face in the longitudinal direction of the light pipe that opens toward the optical plate.

  The light pipe 16 has a long rectangular parallelepiped shape made of a transparent polymer material such as acrylic or PC. In the process of guiding through the light pipe 16, pseudo white light and red light are sufficiently additively mixed. Thus, the white light having a high whiteness is emitted from the emission end face of the light pipe 16. A second reflector 17 is disposed on the bottom surface of the light pipe 16 in order to efficiently perform such additive color mixing and to reduce light leakage from the light pipe 16. Although not clearly shown in FIG. 13, a metal film such as Al or Ag having a high reflectance is also formed on the surface of the flexible substrate 15 facing the light pipe 16. The pseudo white light and red light can be effectively mixed, and the utilization efficiency of the irradiation light can be improved. Furthermore, a small prism group may be formed on the surface of the light pipe 16 that faces the exit surface so that the light emitted from the light pipe 16 becomes more uniform.

  White light incident on the light guide plate 11 from the light pipe 16 is irradiated from a side surface facing the color liquid crystal display element by a small prism group (not shown) formed on the bottom surface of the light guide plate 11 or a rough surface having a roughness distribution. Is done. Also at this time, in order to improve the utilization efficiency of the irradiation light, the first reflecting plate 12 is disposed so as to face the back surface side of the light guide plate 11 where the micro prism group and the rough surface region are formed. .

  The color correction film 10 is adhesively bonded to the liquid crystal side irradiation surface of the light guide plate 11. That is, the embodiment shown in FIG. 13 shows the same configuration as the embodiment shown in FIG.

  These elements are supported and fixed by a support frame 13. The first reflecting plate 12, the light guide plate 11, and the color correction film 10 are arranged so as to overlap each other, and are bonded and fixed to the support frame 13. In addition, the flexible substrate 15 on which the pseudo white LED 14 a and the red LED 14 b are mounted, the light pipe 16, and the second reflecting plate 17 are arranged so as to overlap each other, and are bonded and fixed to the support frame 13. The exit end face of the light pipe 16 and the entrance end face of the light guide plate 11 are disposed so as to face each other.

Thus, according to the present invention, it is possible to configure a thin white light illumination light guide plate unit with a simple structure, and to provide an illumination device suitable for a color liquid crystal element that is becoming thinner and lighter. did it.
The light sources used here are drawn together for simplicity in each figure, but the first LED that emits blue monochromatic light and the first LED that emits red monochromatic light. An additive color mixture that combines green light generated by wavelength conversion from blue monochromatic light, blue light generated by the first LED, and red light generated by the second LED. This is a white light source that obtains white light.

  Here, an LED that emits blue light formed of an InGaN-based or GaN-based material is used as the first LED, and a second LED is formed of a GaP-based or GaAlAs-based mixed crystal material. LED that emits red light is used. The emission wavelength of the first LED is specifically in the range of 430 to 470 nm, and the emission wavelength of the second LED is specifically in the range of 610 to 670 nm.

  In order to obtain the green light by converting the wavelength of the blue light from the first LED, a phosphor that receives the blue light and excites the blue light and the green light is formed on the emission surface of the first LED. As a material for forming this phosphor, a YAG (Yttrium-Aluminum-Garnet) phosphor or an oxide having an emission element of an additive element such as Tb, Ce, Eu and Mn can be used.

  In FIGS. 1, 2, and 3, the light emitted from the white light source 1 is propagated into the light guide plate 2 from an incident portion that is a side end surface of the light guide plate 2. In order to uniformly irradiate the liquid crystal display element 4 with the light propagated inside, a light reflecting plate group, a rough surface having a distribution, or a hologram pattern is formed on the bottom surface of the light guide plate 2. Further, a reflection plate (not shown) is disposed outside the bottom surface of the light guide plate 2 so that the light escaped to the bottom surface side is returned to the liquid crystal display element 4 side to efficiently use the illumination light. Yes.

  On the other hand, the liquid crystal display element 4 controls the polarization state of light passing through each pixel by applying a driving voltage between matrix pixel electrodes sandwiching the liquid crystal in the glass cell. Then, by sandwiching this cell with a pair of polarizing plates arranged orthogonally or in parallel, transmitted light or reflected light having a light intensity corresponding to the polarization state is obtained, and as a result, an image is displayed.

  The liquid crystal display element 4 includes an active matrix type liquid crystal display element that controls a driving voltage by forming a switching element such as a TFT for each pixel, and a driving voltage directly applied to the transparent electrode that forms each pixel from the outside. There are passive matrix liquid crystal display elements to be applied, and the above-described lighting device can be used for either type of liquid crystal display element.

It is sectional drawing which shows typically the basic composition of the liquid crystal display device by this invention. It is sectional drawing which shows typically the example of another structure of the liquid crystal display device by this invention. It is a cross section which shows typically the example of another structure of the liquid crystal display device by this invention. It is a graph which illustrates the emission spectrum of the pseudo white light obtained by the additive color mixture using the blue LED and the phosphor. It is a graph which illustrates the emission spectrum obtained by adding red light to pseudo white light. It is a graph which illustrates the spectral transmittance of the color filter corresponding to each RGB used for a color liquid crystal element. 7 is a graph showing a luminance spectrum of a white image displayed when the liquid crystal element formed with the color filter having the spectral transmittance shown in FIG. 6 is illuminated by the pseudo white light source shown in FIG. 4. 7 is a graph illustrating a luminance spectrum of a white image displayed when the liquid crystal element on which the color filter having the spectral transmittance illustrated in FIG. 6 is formed is illuminated with a white light source having an emission spectrum illustrated in FIG. 5. It is a graph which shows the spectral transmission factor of the color correction film used for this invention. 10 is a graph showing a luminance spectrum of a white image when the color correction film having the spectral transmittance shown in FIG. 9 and the light source of the emission spectrum shown in FIG. 5 are combined and displayed on a color liquid crystal display element. It is a graph which shows the spectral transmission factor of the 2nd color correction film used for this invention. 12 is a graph showing a luminance spectrum when a color liquid crystal element using the color correction film having the spectral transmittance of FIG. 9 and the second color correction film having the spectral transmittance shown in FIG. 11 as a color correction unit is displayed. . It is an assembly perspective view showing typically the composition of the lighting installation by the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 White light source 2 Light guide plate 3, 3a, 3b Color correction film 4 Color liquid crystal element 10 Color correction film 11 Light guide plate 12 1st reflecting plate 13 Support frame 14a Pseudo white LED
14b Red LED
15 Flexible substrate 16 Light pipe 17 Second reflector

Claims (10)

A first light source that emits blue monochromatic light; a second light source that emits red monochromatic light; green light generated by wavelength conversion from the blue monochromatic light; and light emitted from the first light source A white light source that obtains white light by additive color mixing of blue light and red light emitted from the second light source;
An incident surface on which white light from the white light source is incident; and a light guide plate having a light emitting surface from which the white light is emitted as illumination light.
An illuminating device according to claim 1, wherein at least one of the incident surface and the light emitting surface of the light guide plate is provided with a color correcting means by subtractive color mixing.   2. The illumination device according to claim 1, wherein the color correction unit is a polymer film having a function of absorbing or reflecting light in a predetermined wavelength region at a predetermined ratio.   The color correcting means has a function of absorbing or reflecting light in the first wavelength region at a predetermined ratio and a function of absorbing or reflecting light in the second wavelength region at a predetermined ratio. The illuminating device according to claim 1, further comprising a second polymer film having:   4. The illumination device according to claim 2, wherein the polymer film is a mixture of pigments or dyes for absorbing light having a predetermined wavelength at a predetermined concentration.   The lighting device according to claim 2 or 3, wherein an optical multilayer film for reflecting light of a predetermined wavelength at a predetermined ratio is formed on the surface of the polymer film. A first light source that emits blue monochromatic light; a second light source that emits red monochromatic light; green light generated by wavelength conversion from the blue monochromatic light; and light emitted from the first light source A white light source that obtains white light by an additive color mixture of blue light and blue light emitted from the second light source;
A light guide plate having an incident surface on which the white light is incident, and a light emitting surface from which the white light is emitted as illumination light;
A liquid crystal display element irradiated with the illumination light, and
A liquid crystal display device, wherein color correction means by subtractive color mixing is provided between at least one of the white light source and the incident surface and between the light emitting surface and the liquid crystal display element.   The liquid crystal display device according to claim 6, wherein the color correction unit has a characteristic of absorbing light in a wavelength band of 570 to 610 nm.   8. The liquid crystal display device according to claim 7, wherein second color correction means having an absorption peak in the vicinity of a wavelength of 500 nm is provided between the white light source and the liquid crystal display element. A first light source that emits blue monochromatic light and a second light source that emits red monochromatic light, green light generated by wavelength conversion from the blue monochromatic light, and light emitted from the first light source A white light source that obtains white light by additive color mixing of blue light and red light emitted from the second light source;
A light guide plate for irradiating the liquid crystal display element with white light from the white light source, and
The liquid crystal display device according to claim 1, wherein the white light is subjected to color correction by subtractive color mixing before being irradiated onto the liquid crystal display element.   The liquid crystal display device according to any one of claims 6 to 9, wherein the liquid crystal display device is a color liquid crystal display device including a color filter including RGB.

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