JP4545188B2 - LED backlight device and liquid crystal display device - Google Patents

Description

  The present invention relates to an LED backlight device and a liquid crystal display device using the LED backlight device.

  2. Description of the Related Art Conventionally, an LED backlight device has a plurality of LED (Light Emitting Diode) elements as individually molded semiconductor light emitting elements arranged at an appropriate distance, and a diffusion plate on a light emission surface to a liquid crystal panel. To provide a uniform surface emission to the liquid crystal panel.

In a liquid crystal display device using such an LED backlight device, a prism sheet installed on the back surface of the liquid crystal panel, a first diffusion plate installed on the back surface of the prism sheet, and the first diffusion plate A substrate on which a plurality of white LEDs are mounted and a second diffusion plate for taking in external light installed on the back surface of the substrate, and supplying white light from the white LEDs A surface light source is formed by illuminating the liquid crystal panel by taking in outside light (see, for example, Patent Document 1).
JP 2002-311412 A

  However, in the conventional LED backlight device, since a plurality of individually molded LED elements are arranged at an appropriate distance, the LED backlight device becomes thick and the LED backlight device is used. The liquid crystal display device cannot be thinned.

  The present invention solves the problems of the conventional LED backlight device, and uniformly diffuses incident light so as to face the surface of the first substrate to which the LED is fixed opposite to the LED. It is an object of the present invention to provide an LED backlight device and a liquid crystal display device using the LED backlight device that are extremely thin and have a large amount of emitted light by disposing the second substrate.

For this purpose, in the LED backlight device of the present invention, a transparent first substrate having a function of uniformly diffusing incident light, and an inorganic material are laminated and formed as a pn junction device by an epitaxial growth method. An LED laminated thin film fixed to the first surface of the substrate, an anode electrode and a cathode electrode formed on the LED laminated thin film, an anode driver IC and a cathode driver IC for driving the LED laminated thin film to emit light, An anode wiring formed on the first surface of the first substrate for connecting the anode driver IC and the anode electrode of the LED laminated thin film, and a cathode for connecting the cathode driver IC and the cathode electrode of the LED laminated thin film that having a and wiring.

  According to the present invention, the LED backlight device includes the second substrate that is disposed so as to face the surface of the first substrate on which the LED is fixed and is opposite to the LED, and that uniformly diffuses incident light. Have. Thereby, it can be made very thin and the amount of emitted light can be increased.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a side sectional view of an LED backlight device according to a first embodiment of the present invention, FIG. 2 is a perspective view of an LED according to the first embodiment of the present invention, and FIG. 3 is a first embodiment of the present invention. FIG. 4 is a side sectional view of a liquid crystal display device using the LED backlight device according to the first embodiment of the present invention.

  In the figure, 100 is an LED backlight device in the present embodiment, 200 is a liquid crystal panel in the present embodiment, and constitutes a liquid crystal display device as a whole. The LED backlight device 100 is disposed behind the liquid crystal panel 200 with respect to the display surface of the liquid crystal display device and functions as a light source.

  The LED backlight device 100 includes a flat substrate 10 as a first substrate, and a first surface (lower surface in FIG. 1) of the substrate 10, that is, an LED fixed on the surface. It has LED11 as a laminated thin film. The LED 11 includes an LED 11R that emits red light in the LED 11, an LED 11G that emits green light in the LED 11, and an LED 11B that emits blue light in the LED 11. In addition, when describing LED11R, LED11G, and LED11B collectively, it demonstrates as LED11.

  An anode driver IC 31 and a cathode driver IC 32 for driving the LED 11 are disposed on the substrate 10. One end of the anode wiring 12 connected to the anode electrode 14 of each LED 11 is connected to the anode driver IC 31, and one end of the cathode wiring 13 connected to the cathode electrode 15 of each LED 11 is connected to the cathode driver IC 32. Has been.

  Furthermore, the LED backlight device 100 is a plate-like light as a second substrate disposed on the second surface of the substrate 10 facing the first surface, that is, the back surface (the upper surface in FIG. 1). The diffusion plate 40, the protective film 19 formed so as to cover the entire LED 11 fixed to the first surface of the substrate 10, and the surface of the protective film 19 (the lower surface in FIG. 1), that is, the LED 11 And a heat radiating plate 60 fixed by a heat conductive adhesive 50 on the surface opposite to the surface to which is fixed.

  Here, the substrate 10 is preferably made of a quartz substrate or a glass substrate having excellent translucency, or a resin substrate such as acrylic having translucency. An organic insulating film such as a polyimide film or an inorganic insulating film is formed on the surface of the substrate 10 and is flattened so that the surface accuracy is several tens of nanometers or less. The LED 11R that emits red light, the LED 11G that emits green light, and the LED 11B that emits blue light are thin film LEDs each composed of a laminated thin film, and are peeled off from another substrate by a process described later. It is separated and fixed on the substrate 10 by intermolecular force such as hydrogen bonding and integrated.

  The LED 11R that emits red light is a laminated thin film having a heterostructure or a double heterostructure formed by epitaxially growing an inorganic material such as aluminum gallium arsenide or indium aluminum gallium arsenide. The material of the LED 11R may be of any kind as long as it has a light emission region at a wavelength of 620 to 710 nanometers, and is not limited to the above material. The LED 11G that emits green light is a laminated thin film having a heterostructure or a double heterostructure formed by epitaxial growth of an inorganic material such as aluminum gallium indium phosphorus or gallium phosphorus. The LED 11G may be of any kind as long as it has a light emission region at a wavelength of 500 to 580 nanometers, and is not limited to the above material. Further, the LED 11B emitting blue light is a laminated thin film having a heterostructure or a double heterostructure formed by epitaxially growing an inorganic material such as gallium nitride or indium gallium nitride. The LED 11B may be of any kind as long as it has a light emission region at a wavelength of 450 to 500 nanometers, and is not limited to the above material.

  Further, the anode electrode 14 and the cathode electrode 15 are metal electrodes formed by thin film lamination of gold or aluminum, or metal materials such as gold or aluminum and nickel, titanium, etc. It is connected.

  The anode wiring 12 and the cathode wiring 13 are metal wiring formed by depositing gold or aluminum, or a metal material such as gold or aluminum and nickel, titanium, etc., and the anode electrode 14 and the cathode of each LED 11. Each is connected to the electrode 15. Since the anode wiring 12 has one end connected to the anode driver IC 31 and the cathode wiring 13 connected to the cathode driver IC 32, the anode electrode 14 and the cathode electrode 15 of each LED 11 are connected to the anode wiring 12 and The cathode driver IC 31 and the cathode driver IC 32 are connected through the cathode wiring 13.

  The light diffusion plate 40 is made of a plastic substrate having translucency. Further, it has a function of uniformly diffusing incident light, and is formed of a polymer material such as polycarbonate or polyethylene terephthalate. The light diffusing plate 40 is aligned and fixed so as to face the surface of the substrate 10 facing the surface on which the LEDs 11 are formed.

  The protective film 19 is formed of an organic insulating film such as a polyimide film or an inorganic insulating film such as a silicon oxide film so as to cover all of the LED 11 formed on the substrate 10, the anode electrode 14, and the cathode electrode 15. Note that the anode driver IC 31 and the cathode driver IC 32 are disposed outside the protective film 19 on the substrate 10.

  Further, a heat radiating plate 60 made of a metal such as aluminum and coated with a thermally conductive adhesive 50 having a thermal conductivity such as a silicone resin is bonded and fixed on the protective film 19.

  The anode driver IC 31 has a function of supplying a current to the LED 11 in response to a lighting signal, and for example, a circuit such as a constant current circuit and an amplifier circuit is integrated. The anode wiring 12 connected to the anode electrode 14 of the LED 11 is connected to the drive element of the anode driver IC 31. In the example shown in the figure, the anode driver IC 31 is mounted on the substrate 10. However, the anode driver IC 31 does not necessarily have to be mounted on the substrate 10, and is disposed on another wiring board (not shown). It may be provided.

  The cathode driver IC 32 has a function of sucking current from the LED 11, and a switch circuit such as a transistor is integrated therein. The cathode wiring 13 connected to the cathode electrode 15 of the LED 11 is connected to the cathode driver IC 32. In the example shown in the figure, the cathode driver IC 32 is mounted on the substrate 10. However, the cathode driver IC 32 does not necessarily have to be mounted on the substrate 10, and is arranged on another wiring board (not shown). It may be provided.

  Next, a process for forming the LED 11 on the substrate 10 will be described.

  FIG. 5 is a diagram showing a process of peeling the laminated thin film of the LED according to the first embodiment of the present invention, and FIG. 6 is a process of integrating the laminated thin film of the LED with the substrate according to the first embodiment of the present invention. FIG.

  In the figure, reference numeral 18 denotes an LED laminated thin film, which has an elongated strip shape or strip shape. For example, the LED laminated thin film 18R for the LED 11R that emits red light is a laminated thin film that includes a plurality of layers such as aluminum gallium arsenide and indium aluminum gallium arsenide and has a heterostructure or a double heterostructure.

  Reference numeral 17 denotes a sacrificial layer, which is a film that is easily etched by a stripping etchant, which will be described later, for example, an aluminum arsenic layer film, for peeling the LED laminated thin film 18 from the base material 16. It is formed between the laminated thin films 18.

  Further, the base material 16 is made of, for example, a material such as gallium arsenide, gallium nitride, or sapphire, and a material constituting the LED laminated thin film 18 is formed on the base material 16 by vapor phase growth method such as MOCVD method. Epitaxially grow.

  Next, a process of peeling the LED 11 which is a laminated thin film epitaxially grown from the base material 16 will be described.

  For example, if the total size of the LEDs 11R, 11G, and 11B of the LED backlight device 100 is a square with a side length of 20 millimeters, in order to obtain the LEDs 11 of each color, the length is larger than 20 millimeters. In addition, the LED laminated thin film 18 is formed in a strip shape having a width larger than 1/3 of 20 millimeters. In this case, the LED laminated thin film 18 is formed in a strip shape by using a photolithography etching technique widely used in a semiconductor process and using phosphoric acid phosphorous acid as an etching solution.

  Thereafter, the base material 16 on which the LED laminated thin film 18 to be peeled is formed is immersed in a peeling etching solution such as a hydrogen fluoride solution or a hydrochloric acid solution. Thereby, the sacrificial layer 17 is etched, and the LED laminated thin film 18 is peeled off from the base material 16.

  Then, the peeled LED laminated thin film 18 is pressed onto the substrate 10 whose surface is flattened, and the substrate 10 and the LED laminated thin film 18 are fixed and integrated by an intermolecular force such as hydrogen bonding.

  Here, the outermost surface of the substrate 10 is formed with an organic insulating film such as a polyimide film or an inorganic insulating film such as a silicon oxide film, and is preferably planarized without unevenness with a surface accuracy of several tens of nanometers or less. It is the surface. Thus, by making the outermost surface of the substrate 10 a flat surface without unevenness, the bonding with the LED laminated thin film 18 by intermolecular force such as hydrogen bonding becomes easy.

  Such a process is repeated for the LED laminated thin film 18. Thereby, as shown in FIG. 6, a plurality of rows, for example, three rows of the LED laminated thin films 18R, 18G, and 18B are fixed and integrated on the substrate 10.

  Subsequently, each LED laminated thin film 18 integrated on the substrate 10 is formed with a junction between the anode electrode 14 and the cathode electrode 15 by, for example, a photolithography etching method using phosphoric acid / hydrogen peroxide as an etching solution. Further, the anode electrode 14 and the cathode electrode 15 of the LED 11 and the anode wiring 12 and the cathode wiring 13 connected to the anode electrode 14 and the cathode electrode 15 are formed by vapor deposition, a photolithography etching method or a lift-off method. Further, the anode driver IC 31 and the cathode driver IC 32 are mounted on the substrate 10, and the anode wiring 12 and the cathode wiring 13 are connected to the anode driver IC 31 and the cathode driver IC 32.

  In addition, here, an example in which the LED laminated thin film 18 is formed in a strip shape and the combined dimensions of the LEDs 11R, 11G, and 11B is a square having a side length of 20 millimeters has been described, but the combined dimension is 20 millimeters. The shape is not limited to the above, and the shape may be any shape such as a rectangle, a polygon, a circle, and an oval. Furthermore, although the example which comprised each LED11 with the strip-shaped LED laminated thin film 18 of the same dimension was demonstrated, according to the color scheme and weighting of each color, you may comprise each in a different dimension, and a shape is also a triangle and a square. Any shape such as a polygon, a circle, and an ellipse may be used.

  Moreover, although the example which arrange | positions LED11R, 11G, and 11B one by one was demonstrated, according to required brightness | luminance and the size of the LED backlight apparatus 100, you may arrange | position several LED11R, 11G, and 11B one by one. Accordingly, a necessary number of anode wirings 12 and cathode wirings 13 may be provided.

  Next, the operation of the LED backlight device 100 configured as described above will be described.

  First, when a lighting signal transmitted from a host device (not shown) such as a personal computer is input to the anode driver IC 31, each color is adjusted so that the mixed color of the light emitted from the LEDs 11 becomes a desired white color. Stable currents set at different current values are supplied from the amplifier circuit of the anode driver IC 31 to each anode electrode 14 via each anode wiring 12. When the lighting signal is input to the cathode driver IC 32, the cathode driver IC 32 sucks current from the cathode electrode 15 of the LED 11 through the cathode wiring 13 by the switch circuit, and the LEDs 11R, 11G, and 11B of the respective colors become the lighting signal. It emits light in response. The light emitted from the LEDs 11R, 11G, and 11B is incident on the light diffusing plate 40 as shown by an arrow A in FIG. 1, and each color is uniformly diffused. As shown by an arrow B in FIG. Light is emitted from the light diffusion plate 40.

  In this case, since the heat generated with the light emission of the LEDs 11R, 11G, and 11B diffuses through the protective film 19, the heat conductive adhesive 50, and the heat radiating plate 60, the temperature of the substrate 10 and the light diffusing plate 40 is Little rise.

  Thus, in the present embodiment, the LED 11, the anode wiring 12, and the cathode wiring 13 can be formed by a semiconductor process, and the LED 11, the anode wiring 12, and the cathode wiring 13 can be connected. A very thin LED backlight device 100 can be obtained.

  Next, a second embodiment of the present invention will be described. In addition, about the thing which has the same structure as 1st Embodiment, the description is abbreviate | omitted by providing the same code | symbol. The description of the same operation and the same effect as those of the first embodiment is also omitted.

  FIG. 7 is a side sectional view of the LED backlight device according to the second embodiment of the present invention.

  In the present embodiment, the LED backlight device 100 includes a reflective film 24 and reflects light emitted from the LED 11. Specifically, the reflective film 24 is formed on the protective film 19 so as to cover the entire LED 11 fixed to the first surface of the substrate 10, and further, the second film is formed so as to cover the entire reflective film 24. A protective film 20 is formed.

  In this case, as in the first embodiment, an organic insulating film such as a polyimide film is formed so as to cover all of the LED 11, the anode electrode 14, the cathode electrode 15, the anode wiring 12 and the cathode wiring 13 formed on the substrate 10. Alternatively, the protective film 19 is formed by an inorganic insulating film such as a silicon oxide film. In addition, the anode driver IC 31 and the cathode driver IC 32 are disposed outside the protective film 19 on the substrate 10. In the figure, the anode electrode 14, the cathode electrode 15, the anode wiring 12, the cathode wiring 13, and the anode driver IC 31 are not shown.

  The reflective film 24 is provided to reflect light of each color emitted from the back surface of the LED 11, and is a metal film in which gold or aluminum, or a metal material such as gold or aluminum and nickel, titanium or the like is laminated in a thin film. Is formed on the surface of the protective film 19 and patterned.

  The second protective film 20 is an organic insulating film such as a polyimide film or an inorganic insulating film such as a silicon oxide film, and is formed on the reflective film 24.

  Similarly to the first embodiment, the heat radiating plate 60 made of a metal such as aluminum and the like, in which a thermally conductive adhesive 50 having thermal conductivity such as silicone resin is applied on the second protective film 20. Is bonded and fixed.

  In addition, about the structure of the other point of the LED backlight apparatus 100, since it is the same as that of the said 1st Embodiment, the description is abbreviate | omitted.

  Next, operation | movement of the LED backlight apparatus 100 in this Embodiment is demonstrated.

  First, when a lighting signal transmitted from a host device (not shown) such as a personal computer is input to the anode driver IC 31, each color is adjusted so that the mixed color of the light emitted from the LEDs 11 becomes a desired white color. Stable currents set at different current values are supplied from the amplifier circuit of the anode driver IC 31 to each anode electrode 14 via each anode wiring 12. When the lighting signal is input to the cathode driver IC 32, the cathode driver IC 32 sucks current from the cathode electrode 15 of the LED 11 through the cathode wiring 13 by the switch circuit, and the LEDs 11R, 11G, and 11B of the respective colors become the lighting signal. It emits light in response. The light emitted from the back surfaces of the LEDs 11R, 11G, and 11B is reflected by the reflective film 24, and together with the light emitted from the front surfaces of the LEDs 11R, 11G, and 11B, as indicated by an arrow A in FIG. The light is incident on the light diffusing plate 40 and each color is uniformly diffused, and desired white light is emitted from the light diffusing plate 40 as indicated by an arrow B in FIG.

  In this case, the heat generated along with the light emission of the LEDs 11R, 11G, and 11B is diffused through the protective film 19, the second protective film 20, the reflective film 24, the heat conductive adhesive 50, and the heat dissipation plate 60. The temperatures of the substrate 10 and the light diffusing plate 40 hardly increase.

  As described above, in the present embodiment, the LED backlight device 100 includes the reflective film 24 formed on the surface of the protective film 19 that covers the LEDs 11. Further, the LED 11, the anode wiring 12 and the cathode wiring 13 can be formed by a semiconductor process, and the LED 11 can be connected to the anode wiring 12 and the cathode wiring 13. Therefore, it is possible to provide a thin LED backlight device 100 having higher luminance than that of the first embodiment.

  Next, a third embodiment of the present invention will be described. In addition, about the thing which has the same structure as 1st and 2nd embodiment, the description is abbreviate | omitted by providing the same code | symbol. Also, the description of the same operations and effects as those of the first and second embodiments is omitted.

  FIG. 8 is a side sectional view of an LED backlight device in which an LED according to a third embodiment of the present invention is formed on a light diffusing plate having translucency.

  In the present embodiment, the LED backlight device 100 includes a flat light diffusing plate 40 as a first substrate. Here, the light diffusing plate 40 is made of a polymer material such as polycarbonate or polyethylene terephthalate having translucency and a function of uniformly diffusing incident light.

  An organic insulating film or an inorganic insulating film such as a polyimide film is formed on the surface of the light diffusing plate 40 as in the surface of the substrate 10 in the first embodiment, and the surface accuracy is several tens of nanometers. It is flattened so that In this case, the LED 11R that emits red light, the LED 11G that emits green light, and the LED 11B that emits blue light are thin film LEDs each formed of a laminated thin film, and the steps described in the first embodiment. In the same process, it is peeled from another substrate, and is fixed and integrated on the light diffusion plate 40 by intermolecular force such as hydrogen bonding.

  Further, an anode driver IC 31 and a cathode driver IC 32 for driving the LED 11 are mounted on the surface of the light diffusion plate 40, and the anode electrode 14, the cathode electrode 15, the anode wiring 12 and the cathode wiring 13 are also provided in the first embodiment. It is formed by a process similar to the process described in the first embodiment. In the figure, the anode electrode 14, the cathode electrode 15, the anode wiring 12, the cathode wiring 13, and the anode driver IC 31 are not shown.

  Then, an organic insulating film such as a polyimide film or an inorganic insulating film such as a silicon oxide film is formed so as to cover the LED 11, the anode electrode 14, the cathode electrode 15, the anode wiring 12 and the cathode wiring 13 formed on the light diffusion plate 40. A protective film 19 is formed. In addition, the anode driver IC 31 and the cathode driver IC 32 are disposed outside the protective film 19 on the substrate 10.

  Further, as in the first embodiment, a heat radiating plate 60 made of a metal such as aluminum and coated with a thermally conductive adhesive 50 having a thermal conductivity such as a silicone resin is bonded and fixed on the protective film 19. Is done.

  Next, operation | movement of the LED backlight apparatus 100 in this Embodiment is demonstrated.

  First, when a lighting signal transmitted from a host device (not shown) such as a personal computer is input to the anode driver IC 31, each color is adjusted so that the mixed color of the light emitted from the LEDs 11 becomes a desired white color. Stable currents set at different current values are supplied from the amplifier circuit of the anode driver IC 31 to each anode electrode 14 via each anode wiring 12. When the lighting signal is input to the cathode driver IC 32, the cathode driver IC 32 sucks current from the cathode electrode 15 of the LED 11 through the cathode wiring 13 by the switch circuit, and the LEDs 11R, 11G, and 11B of the respective colors become the lighting signal. It emits light in response. The light emitted from the LEDs 11R, 11G, and 11B is incident on the light diffusion plate 40 as shown by an arrow A in FIG. 8, and each color is uniformly diffused. As shown by an arrow B in FIG. Light is emitted from the light diffusion plate 40.

  In this case, the heat generated with the light emission of the LEDs 11R, 11G and 11B diffuses through the protective film 19, the heat conductive adhesive 50 and the heat radiating plate 60, so the temperature of the light diffusing plate 40 hardly rises. .

  Thus, in this Embodiment, LED11 is directly formed on the surface of the light diffusing plate 40 which has translucency. Further, the LED 11, the anode wiring 12 and the cathode wiring 13 can be formed by a semiconductor process, and the LED 11 can be connected to the anode wiring 12 and the cathode wiring 13. Therefore, it is possible to provide a lighter and thinner LED backlight device 100 with a simpler configuration than the first embodiment.

  Next, a fourth embodiment of the present invention will be described. In addition, about the thing which has the same structure as the 1st-3rd embodiment, the description is abbreviate | omitted by providing the same code | symbol. Explanation of the same operations and effects as those of the first to third embodiments is also omitted.

  9 is a side sectional view of an LED backlight device according to a fourth embodiment of the present invention, FIG. 10 is a perspective view of an LED according to the fourth embodiment of the present invention, and FIG. 11 is a fourth embodiment of the present invention. The figure which shows arrangement | positioning of LED in the form of FIG. 12, FIG. 12 is a figure which shows other arrangement | positioning of LED in the 4th Embodiment of this invention.

  In the present embodiment, the LED backlight device 100 includes a flat substrate 10 as a first substrate, and an LED 11 as an LED laminated thin film fixed on the substrate 10. The LED 11 includes LED 11R1, LED 11R2, and LED 11R3 that emit red light among the LED 11, LED 11G1, LED 11G2, and LED 11G3 that emit green light within the LED 11, and LED 11B1, LED 11B2, and LED 11B3 light emitting blue light within the LED 11. Have

  LED11R1, LED11R2, LED11R3, LED11G1, LED11G2, LED11G3, LED11B1, LED11B2, and LED11B3 are described as LED11 when collectively explained, and LED11R1, LED11R2, and LED11R3 are explained as LED11R when collectively explained. The LED 11G, the LED 11G2, and the LED 11G3 will be described as the LED 11G, and the LED 11B1, the LED 11B2, and the LED 11B3 will be described as the LED 11B.

  Further, the number of the LEDs 11 can be arbitrarily set, but here, it is assumed that there are nine for convenience of illustration. Further, the arrangement of the LEDs 11 can be arbitrarily set, but here, it is assumed that the array is an array arranged in a grid. That is, in the example shown in FIGS. 10 and 11, the LEDs 11 are arranged at regular intervals in a 3 × 3 square lattice pattern.

  Each row includes one LED 11R that emits red light, one LED 11G that emits green light, and one LED 11B that emits blue light, and are connected so as to be connected in series. In this case, one end of the anode wiring 12 connected to the anode electrode 14 of the LED 11 closest to the anode driver IC 31 in each column is connected to the anode driver IC 31. The cathode driver IC 32 is connected to one end of the cathode wiring 13 connected to the cathode electrode 15 of the LED 11 farthest from the anode driver IC 31 in each column. Furthermore, the anode electrode 14 and the cathode electrode 15 of the LED 11 adjacent in each column are connected to the connection wiring 21. That is, the LEDs 11 are connected in series for each column via the connection wiring 21, and the anode electrode 14 and the cathode electrode 15 of the LED 11 located at both ends of each column are connected to the anode driver IC 31 and the cathode via the anode wiring 12 and the cathode wiring 13. The driver IC 32 is connected.

  Further, the LED backlight device 100 is a flat light as a second substrate disposed on the second surface of the substrate 10 facing the first surface, that is, the back surface (the upper surface in FIG. 9). The diffusion plate 40, the protective film 19 formed so as to cover the entire LED 11 fixed to the first surface of the substrate 10, and the surface of the protective film 19 (the lower surface in FIG. 9), that is, the LED 11 And a heat radiating plate 60 fixed by a heat conductive adhesive 50 on the surface opposite to the surface to which is fixed.

  Here, the substrate 10 is preferably made of a quartz substrate or a glass substrate having excellent translucency, or a resin substrate such as acrylic having translucency. An organic insulating film such as a polyimide film or an inorganic insulating film is formed on the surface of the substrate 10 and is flattened so that the surface accuracy is several tens of nanometers or less. The LED 11R that emits red light, the LED 11G that emits green light, and the LED 11B that emits blue light are thin film LEDs each formed of a laminated thin film, and are peeled off from another substrate by a process described later. It is fixed and integrated on 10 by intermolecular forces such as hydrogen bonds.

  The LED 11R emitting red light is a laminated thin film having a heterostructure or a double heterostructure formed by epitaxially growing an inorganic material such as aluminum gallium arsenide or indium aluminum gallium arsenide. The material of the LED 11R may be of any kind as long as it has a light emission region at a wavelength of 620 to 710 nanometers, and is not limited to the above material. The LED 11G that emits green light is a laminated thin film having a heterostructure or a double heterostructure formed by epitaxial growth of an inorganic material such as aluminum gallium indium phosphorus or gallium phosphorus. The LED 11G may be of any kind as long as it has a light emission region at a wavelength of 500 to 580 nanometers, and is not limited to the above material. Further, the LED 11B emitting blue light is a laminated thin film having a heterostructure or a double heterostructure formed by epitaxially growing an inorganic material such as gallium nitride or indium gallium nitride. The LED 11B may be of any kind as long as it has a light emission region at a wavelength of 450 to 500 nanometers, and is not limited to the above material.

  Further, the anode electrode 14 and the cathode electrode 15 are metal electrodes formed by thin film lamination of gold or aluminum, or metal materials such as gold or aluminum and nickel, titanium, etc. It is connected.

  The anode wiring 12, the cathode wiring 13, and the connection wiring 21 are metal wiring formed by thin film stacking of gold or aluminum, or gold or aluminum and a metal material such as nickel or titanium, and emits red light. The LED 11R, the LED 11G that emits green light, and the LED 11B that emits blue light are respectively connected to the anode electrode 14 and the cathode electrode 15 so as to be connected in series.

  For example, as shown in FIG. 11, in a row of LEDs 11 composed of LEDs 11R1, 11G1, and 11B1 arranged in a line, an anode wiring 12 is connected to the anode electrode 14 of the LED 11R1, and the cathode electrode 15 of the LED 11R1 and the anode electrode of the LED 11G1 14 is connected by a connecting wire 21, the cathode electrode 15 of the LED 11G1 and the anode electrode 14 of the LED 11B1 are connected by a connecting wire 21, the cathode electrode 15 of the LED 11B1 and the cathode wire 13 are connected, and the LEDs 11R1, 11G1, and 11B1 are electrically connected. Are connected in series. Similarly, in the other columns of the LEDs 11, the LEDs 11G2, 11B2, and 11R2 of the respective colors arranged in a line and the LEDs 11B3, 11R3, and 11G3 are electrically connected in series one by one. One end of the anode wiring 12 is connected to the anode driver IC 31, and one end of the cathode wiring 13 is connected to the cathode driver IC 32. Accordingly, the anode electrode 14 and the cathode electrode 15 of each LED 11 are connected to the anode driver IC 31 and the cathode driver IC 32 via the anode wiring 12, the cathode wiring 13, and the connection wiring 21, respectively.

  In the example shown in FIGS. 10 and 11, a total of nine LEDs 11 are arranged at regular intervals in a three-column, three-row square lattice pattern. However, the luminance required for the LED backlight device 100 and the LED backlight device 100 are not limited. Depending on the size, the number and arrangement of the LEDs 11 can be appropriately changed. For example, as shown in FIG. 12, a total of 12 LEDs 11 may be arranged to form four triangular islands or groups of three LEDs 11.

  In this case, in the combination of the LEDs 11R1, 11G1, and 11B1 arranged in a triangle shape, the anode wiring 12 is connected to the anode electrode 14 of the LED 11R1, and the cathode electrode 15 of the LED 11R1 and the anode electrode 14 of the LED 11G1 are connected by the connection wiring 21. The cathode electrode 15 of the LED 11G1 and the anode electrode 14 of the LED 11B1 are connected by a connection wiring 21, the cathode electrode 15 of the LED 11B1 and the cathode wiring 13 are connected, and the LEDs 11R1, 11G1, and 11B1 are electrically connected in series. Similarly, in the other three combinations, LEDs 11R, 11G, and 11B arranged in a triangle shape are electrically connected in series one by one. One end of the anode wiring 12 is connected to the anode driver IC 31, and one end of the cathode wiring 13 is connected to the cathode driver IC 32. Accordingly, the anode electrode 14 and the cathode electrode 15 of each LED 11 are connected to the anode driver IC 31 and the cathode driver IC 32 via the anode wiring 12, the cathode wiring 13 and the connection wiring 21, respectively.

  The LED backlight device 100 includes a flat light diffusion plate 40. Here, the light diffusing plate 40 is made of a plastic substrate having translucency. Further, it has a function of uniformly diffusing incident light, and is formed of a polymer material such as polycarbonate or polyethylene terephthalate.

  The protective film 19 is formed of an organic insulating film such as a polyimide film or an inorganic insulating film such as a silicon oxide film so as to cover all of the LED 11 formed on the substrate 10, the anode electrode 14, and the cathode electrode 15. Note that the anode driver IC 31 and the cathode driver IC 32 are disposed outside the protective film 19 on the substrate 10.

  Further, a heat radiating plate 60 made of a metal such as aluminum and coated with a thermally conductive adhesive 50 having a thermal conductivity such as a silicone resin is bonded and fixed on the protective film 19.

  The anode driver IC 31 has a function of supplying a current to the LED 11 in response to a lighting signal, and for example, a circuit such as a constant current circuit and an amplifier circuit is integrated. The anode wiring 12 connected to the anode electrode 14 of the LED 11 is connected to the drive element of the anode driver IC 31. In the example shown in the figure, the anode driver IC 31 is mounted on the substrate 10. However, the anode driver IC 31 does not necessarily have to be mounted on the substrate 10, and is disposed on another wiring board (not shown). It may be provided.

  The cathode driver IC 32 has a function of sucking current from the LED 11, and a switch circuit such as a transistor is integrated therein. The cathode wiring 13 connected to the cathode electrode 15 of the LED 11 is connected to the cathode driver IC 32. In the example shown in the figure, the cathode driver IC 32 is mounted on the substrate 10. However, the cathode driver IC 32 does not necessarily have to be mounted on the substrate 10, and is arranged on another wiring board (not shown). It may be provided.

  Next, a process for forming the LED 11 on the substrate 10 will be described.

  FIG. 13 is a diagram showing a process of peeling the laminated thin film of the LED according to the fourth embodiment of the present invention, and FIG. 14 is a process of integrating the laminated thin film of the LED with the substrate according to the fourth embodiment of the present invention. FIGS. 15A and 15B are second diagrams showing a process of integrating a laminated thin film of LEDs with a substrate according to the fourth embodiment of the present invention.

  In the figure, reference numeral 18 denotes an LED laminated thin film, which has a rectangular shape. For example, the LED laminated thin film 18R for the LED 11R that emits red light is a laminated thin film that includes a plurality of layers such as aluminum gallium arsenide and indium aluminum gallium arsenide and has a heterostructure or a double heterostructure.

  Reference numeral 17 denotes a sacrificial layer, which is a film that is easily etched by a stripping etchant, for example, an aluminum arsenic layer film, for peeling the LED laminated thin film 18 from the base material 16. Formed between.

  Further, the base material 16 is made of, for example, a material such as gallium arsenide, gallium nitride, or sapphire, and a material constituting the LED laminated thin film 18 is formed on the base material 16 by vapor phase growth method such as MOCVD method. Epitaxially grow.

  Next, a process of peeling the LED 11 which is a laminated thin film epitaxially grown from the base material 16 will be described.

  For example, if the size of each LED 11 of the LED backlight device 100 is a square with a side length of 2 millimeters, a larger LED laminated thin film 18 is formed. In this case, the photolithography etching technique widely used in the semiconductor process is used, and the LED laminated thin film 18 is formed in a square shape using phosphoric acid / hydrogen peroxide as an etching solution.

  Thereafter, the base material 16 on which the LED laminated thin film 18 to be peeled is formed is immersed in a peeling etching solution such as a hydrogen fluoride solution or a hydrochloric acid solution. Thereby, the sacrificial layer 17 is etched, and the LED laminated thin film 18 is peeled off from the base material 16.

  Then, the peeled LED laminated thin film 18 is pressed onto the substrate 10 whose surface is flattened, and the substrate 10 and the LED laminated thin film 18 are fixed and integrated by an intermolecular force such as hydrogen bonding.

  Here, the outermost surface of the substrate 10 is formed with an organic insulating film such as a polyimide film or an inorganic insulating film such as a silicon oxide film, and is preferably planarized without unevenness with a surface accuracy of several tens of nanometers or less. It is the surface. Thus, by making the outermost surface of the substrate 10 a flat surface without unevenness, the bonding with the LED laminated thin film 18 by intermolecular force such as hydrogen bonding becomes easy.

  Such a process is repeated for the LED laminated thin film 18. As a result, as shown in FIG. 14 or 15, the LED laminated thin films 18R1, 18R2, 18R3, and 18R4 are formed so as to form four square lattice-shaped or triangle-shaped islands of a plurality of columns, for example, three columns and three rows. The LED laminated thin films 18G1, 18G2, 18G3, and 18G4 and the LED laminated thin films 18B1, 18B2, 18B3, and 18B4 are fixed on the substrate 10 and integrated.

  Subsequently, a joined portion of the anode electrode 14 and the cathode electrode 15 is formed on each of the LED laminated thin films 18 integrated on the substrate 10 by, for example, a photolithography etching method using phosphoric acid / hydrogen peroxide as an etching solution. Further, the anode electrode 14 and the cathode electrode 15 of the LED 11 and the anode wiring 12 and the cathode wiring 13 connected to the anode electrode 14 and the cathode electrode 15 are formed by vapor deposition, a photolithography etching method or a lift-off method. Further, the anode driver IC 31 and the cathode driver IC 32 are mounted on the substrate 10, and the anode wiring 12 and the cathode wiring 13 are connected to the anode driver IC 31 and the cathode driver IC 32.

  In addition, here, an example in which the LED laminated thin film 18 is a square having a side length of 2 millimeters has been described. However, the dimensions are not limited to 2 millimeters, depending on the color scheme and weighting of each color. The dimensions may be different from each other, and the shape may be any shape such as a triangle, a square, a polygon, a circle, and an ellipse.

  Next, the operation of the LED backlight device 100 configured as described above will be described.

  First, a combination of three LEDs 11 in which LED 11R that emits red light, LED 11G that emits green light, and LED 11B that emits blue light one by one are connected in series one by one. A lighting signal transmitted from the device is input to the anode driver IC 31. Then, a stable current is supplied to the anode electrode 14 of the first LED 11 of each combination from a circuit such as a constant current circuit and an amplifier circuit of the anode driver IC 31 via the anode wiring 12. When the lighting signal is input to the cathode driver IC 32, the cathode driver IC 32 sucks current from the cathode electrode 15 of the third LED 11 of each combination through the cathode wiring 13 by the switch circuit. As a result, current flows from the anode driver IC 31 to the cathode driver IC 32 through the three LEDs 11 connected in series one by one for each color, and the LEDs 11 for each color emit light in response to the lighting signal.

  In this case, in all combinations, the LED 11R that emits red light, the LED 11G that emits green light, and the LED 11B that emits blue light are connected in series one by one. For example, it is possible to operate all the LEDs 11 having three different basic characteristics under the same supply voltage and current conditions.

  Moreover, since the heat | fever generate | occur | produced with light emission of LED11R, 11G, and 11B diffuses through the protective film 19, the heat conductive adhesive 50, and the heat sink 60, the temperature of the board | substrate 10 and the light diffusing plate 40 is almost. Does not rise.

  As described above, in the present embodiment, the LED 11 is configured such that a plurality of combinations in which the LED 11R that emits red light, the LED 11G that emits green light, and the LED 11B that emits blue light are connected in series one by one are configured. It is arranged. As in the first embodiment, the LED 11, the anode wiring 12, and the cathode wiring 13 can be formed by a semiconductor process. Accordingly, it is possible to provide a large-sized, high-brightness, thin LED backlight device 100 having a simpler circuit configuration than that of the first embodiment.

  In addition, this invention is not limited to the said embodiment, It can change variously based on the meaning of this invention, and does not exclude them from the scope of the present invention.

It is a sectional side view of the LED backlight apparatus in the 1st Embodiment of this invention. It is a perspective view of LED in the 1st Embodiment of this invention. It is a perspective view of the heat sink in the 1st Embodiment of this invention. It is a sectional side view of the liquid crystal display device using the LED backlight apparatus in the 1st Embodiment of this invention. It is a figure which shows the process of peeling the laminated thin film of LED in the 1st Embodiment of this invention. It is a figure which shows the process of integrating the laminated thin film of LED in the board | substrate in the 1st Embodiment of this invention. It is a sectional side view of the LED backlight apparatus in the 2nd Embodiment of this invention. It is a sectional side view of the LED backlight apparatus which formed LED in the 3rd Embodiment of this invention in the light diffusing plate which has translucency. It is a sectional side view of the LED backlight apparatus in the 4th Embodiment of this invention. It is a perspective view of LED in the 4th Embodiment of this invention. It is a figure which shows arrangement | positioning of LED in the 4th Embodiment of this invention. It is a figure which shows other arrangement | positioning of LED in the 4th Embodiment of this invention. It is a figure which shows the process of peeling the laminated thin film of LED in the 4th Embodiment of this invention. It is a 1st figure which shows the process of integrating the laminated thin film of LED in the board | substrate in the 4th Embodiment of this invention. It is a 2nd figure which shows the process of integrating the laminated thin film of LED in the board | substrate in the 4th Embodiment of this invention.

Explanation of symbols

10 Substrate 11, 11R, 11R1, 11R2, 11R3, 11G, 11G1, 11G2, 11G3, 11B, 11B1, 11B2, 11B3 LED
12 Anode wiring 13 Cathode wiring 14 Anode electrode 15 Cathode electrode 16 Base material 17 Sacrificial layer 18, 18R, 18R1, 18R2, 18R3, 18G, 18G1, 18G2, 18G3, 18B, 18B1, 18B2, 18B3 LED laminated thin film 19 Protective film 20 Second protective film 21 Connecting wiring 24 Reflecting film 31 Anode driver IC
32 Cathode driver IC
40 Light Diffusing Plate 60 Heat Dissipating Plate 100 LED Backlight Device 200 Liquid Crystal Panel

Claims (8)

(A) a translucent first substrate having a function of uniformly diffusing incident light;
(B) an LED laminated thin film in which an inorganic material is laminated and formed as a pn junction device by an epitaxial growth method, and is fixed to the first surface of the first substrate;
(C) an anode electrode and a cathode electrode formed on the LED laminated thin film;
(D) an anode driver IC and a cathode driver IC that drive the LED laminated thin film to emit light;
(E) An anode wiring that is formed on the first surface of the first substrate and connects the anode driver IC and the anode electrode of the LED laminated thin film; and the cathode driver IC and the cathode electrode of the LED laminated thin film. An LED backlight device having a cathode wiring to be connected. The LED laminated thin film is fixed to the first surface of the first substrate by intermolecular force,
LED laminated thin film that emits red light having a wavelength of 620 to 710 nanometers,
LED laminated thin film that emits green light having a wavelength of 500 to 580 nanometers;
The LED backlight device according to claim 1 , comprising an LED laminated thin film that emits blue light having a wavelength of 450 to 500 nanometers. 2. The LED backlight device according to claim 1 , wherein an organic insulating film or an inorganic insulating film is formed on the first surface of the first substrate and is planarized. 2. The LED backlight device according to claim 1 , wherein the LED laminated thin film is fixed to the first surface of the first substrate with an interval in a matrix direction. LED laminated thin film that emits red light with a wavelength of 620 to 710 nanometers, LED laminated thin film that emits green light with a wavelength of 500 to 580 nanometers, and an LED laminated thin film that emits blue light with a wavelength of 450 to 500 nanometers An anode wiring for connecting the anode electrode of the LED laminated thin film located at one end in the LED group constituted by a combination of the above and the anode driver IC;
A cathode wiring connecting the cathode electrode of the LED laminated thin film located at one end in the LED group and the cathode driver IC;
The LED backlight device according to claim 1 , further comprising a connection wiring that serially connects the LED laminated thin films in the LED group. An insulating first protective film formed to cover the LED laminated thin film on a first surface of the first substrate to which the LED laminated thin film is fixed; and a reflective film formed on the protective film; , LED backlight device according to any one of claims 1 to 5, and a second protective film formed so as to cover the reflective film insulation. Any of claims 1-5, further comprising a first substrate first surface formed on an insulating protective film which is fixed the LED thin-film layered structure of, and a heat sink disposed over the protective film The LED backlight device according to claim 1. A liquid crystal display device comprising the LED backlight device according to any one of claims 1 to 7, further comprising a liquid crystal panel.

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