Patent Abstract:
Light from an LED (light-emitting diodes) has strong directional characteristics; therefore, lighting over large area, as well as control of the quality or the distribution of lighting was impossible. Placing a liquid-crystal panel in front of an LED (light-emitting diodes) enables to control light from the LED and the quality or the distribution of lighting.

Full Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a lighting apparatus using LEDs that can control the quality and the area of lighting by combining LEDs with a liquid-crystal panel. 
       BACKGROUND ART 
       [0002]    An LED, which emits light by applying a direct voltage to a p-n junction in a compound semiconductor, has been used for home lighting as a result of the recent remarkable progress of technologies. Multi-layered p-n junctions, as well as LEDs (light-emitting diode) mounted on a board have been made it possible to use for high power lighting. An LED lighting, however, because of the structure of its light emitting part, has strong directional characteristics; therefore the use of the LED lighting was limited to downlights. Unlike conventional incandescent bulbs or florescent lamps, an LED lighting was not able to illuminate large areas of a room. It was also not able to control the quality or the area of lighting. 
       PRIOR ART DOCUMENTS 
     Patent Documents 
       [0003]    Patent Document 1: JP-A-2008-28275 
         [0004]    Patent Document 2: JP-T-2009-500232 
         [0005]    Patent Document 3: JP-A-HEI11-353907 
         [0006]    Patent Document 4: JP-A-HEI05-210077 
         [0007]    Patent Document 5: JP 3913184 
         [0008]    Patent Document 6: JP-A-2004-264549 
         [0009]    Patent Document 7: U.S. Pat. No. 6,859,333 
       Non-Patent Documents 
       [0010]    Non-Patent Document 1: Richard Stevenson, “The LED&#39;s dark secret”, IEEE Spectrum, 08.09, 2009, pp. 22-27 
         [0011]    Non-Patent Document 2: Kanji Bando, “Development of LED lighting (1)”, Journal of the Illuminating Engineering Institute of Japan, VOL 92, No. 6, 2008, pp. 301-306 
         [0012]    Non-Patent Document 3: Special Feature Article “LED”, Nihon Keizei Shinbun, 08.30.2009, p. 6 
         [0013]    Non-Patent Document 4: Jun Okazaki, Masaaki Kato, and Katsuyuki Konishi, “Present and Future of LEDs for illuminations”, Sharp Corporation Technical Report, VOL99, 8, 2009, pp. 10-16 
         [0014]    Non-Patent Document 5: Shoji Yokota, “LED Device for Illuminations”, Sharp Corporation Technical Report, VOL99, 8, 2009, pp. 17-19 
         [0015]    Non-Patent Document 6: Shoichi Matsumoto and Kazuyoshi Tsunoda, “Liquid Crystals—Fundamental and Applications”, Kogyo Chosakai Publishing Inc., pp 341-342 
       SUMMARY OF INVENTION 
     Problems to Be Solved by the Invention 
       [0016]    Conventional incandescent bulbs or florescent lamps can illuminate over a large area because of the line-emitting or surface-emitting structure. On the other hand, an LED (light-emitting diode), an extremely small chip, is a point light source. The light can be scattered by positioning reflective plates in the behind or in the surroundings of itself, or by coating inside a glass container with a diffusion paint. However, it was not able to illuminate large areas of a room. It was not possible for LEDs to change the brightness partially as required. 
       Means to Solve the Problems 
       [0017]    In order to solve these problems, the present invention is a lighting apparatus placing a liquid-crystal panel in front of LEDs (light-emitting diodes). The directions of long and thin liquid crystal molecules are varied by an applied electric field and its characteristics to light are changed. Therefore, liquid crystals are widely used for displays. 
         [0018]    A liquid-crystal panel is made by inserting liquid crystals between two opposite electrode plates. In a typical liquid crystal material, when no voltage is applied between the electrode plates, liquid crystal molecules become parallel to the electrode plates as a result of the boundary condition. When a voltage is applied, the liquid crystal molecules become parallel to the electric field, namely, become vertical to the plates. Therefore, when no voltage is applied, light vertical to the liquid-crystal panel is reflected, whereas when a voltage is applied, the light is passed through. In addition, the optical refractive index of the liquid crystal is changed by the applied voltage. 
         [0019]      FIG. 1A  shows the basic structure of a lighting apparatus of the present invention. The lighting apparatus includes: an LED substrate  1 ; LEDs (light-emitting diodes)  2 ; light emitted from the LEDs (light-emitting diodes)  3 ; a liquid-crystal panel  4 ; and light  5  from the liquid-crystal panel  4 . Typically, light from the liquid-crystal panel is scattered or dispersed if the structure or the constituent of the liquid-crystal panel  4  is not uniform. 
       Effects of Invention 
       [0020]    With the LED lighting apparatus of the present invention, the distribution of illumination light from LEDs can be controlled, thereby unprecedented lighting such as concentrating, dispersing, and/or scattering light for desired areas, or illuminating with indirect lighting for an entire room is possible, improving lighting quality significantly. In addition, the conventional two lighting apparatuses will be replaced by one lighting apparatus of the present invention, and thus this invention contributes a lot to the energy-saving and environment problems. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0021]      FIG. 1A  is a sectional view of a basic structure of a lighting apparatus of the present invention. 
           [0022]      FIG. 1B  is a sectional view showing the detail of a basic structure of a lighting apparatus of the present invention. 
           [0023]      FIG. 1C  shows a direction of liquid crystal molecules when no voltage is applied to a liquid-crystal panel of a lighting apparatus of the present invention. 
           [0024]      FIG. 1D  shows a direction of liquid crystal molecules when a voltage is applied to a liquid-crystal panel of a lighting apparatus of the present invention. 
           [0025]      FIG. 2A  is a sectional view of a lighting apparatus of the present invention in which a liquid-crystal panel having functions of a concave lens is placed. 
           [0026]      FIG. 2B  is a sectional views showing the detail of a structure of a lighting apparatus of the present invention in which a liquid-crystal panel has microlenses having functions of a concave lens. 
           [0027]      FIG. 2C  is a sectional view showing the detail of a structure of a lighting apparatus of the present invention in which a liquid-crystal panel having an area of no electrode. 
           [0028]      FIG. 2D  is a sectional view showing the detail of a structure of a lighting apparatus of the present invention in which a liquid-crystal panel has microlenses with functions of a convex lens. 
           [0029]      FIG. 2E  is a sectional view showing the detail of a structure of a lighting apparatus of the present invention in which a liquid-crystal panel has a Fresnel structure of functions of a convex lens. 
           [0030]      FIG. 2F  is a sectional view showing the detail of a structure of a lighting apparatus o of the present invention in which a liquid-crystal panel has microlenses of various functions. 
           [0031]      FIG. 3A  is a sectional view of a lighting apparatus of the present invention in which a polymer-dispersed liquid-crystal panel is placed. 
           [0032]      FIG. 3B  shows a direction of liquid crystal molecules with zero voltage applied to a polymer-dispersed liquid-crystal panel of the present invention. 
           [0033]      FIG. 3C  shows a direction of liquid crystal molecules with a voltage applied to a polymer-dispersed liquid crystal panel of the present invention. 
           [0034]      FIG. 4  is a sectional view of a lighting apparatus of the present invention placing liquid-crystal panel sections of different functions. 
           [0035]      FIG. 5  is a sectional view of a lighting apparatus of the present invention placing liquid-crystal panel sections of different functions alternatively. 
           [0036]      FIG. 6  is a sectional view of a lighting apparatus of the present invention placing liquid-crystal panels of different functions in layer. 
           [0037]      FIG. 7  is a sectional view of a bulb-shaped lighting apparatus of the present invention. 
           [0038]      FIG. 8A  is a sectional view of a bulb-shaped lighting apparatus placing liquid-crystal panels of different functions in layer. 
           [0039]      FIG. 8B  is a sectional view of a bulb-shaped lighting apparatus of the present invention placing curved-surface liquid-crystal panels of different functions in layer. 
           [0040]      FIG. 9  shows a lighting apparatus for ceilings. 
           [0041]      FIG. 10A  is a plan view of a liquid-crystal panel used in the present invention. 
           [0042]      FIG. 10A  is a plan view of an example of a liquid-crystal panel used in the present invention. 
           [0043]      FIG. 10B  is a sectional view of a liquid-crystal panel used in the present invention. 
           [0044]      FIG. 10C  is a sectional view of a liquid-crystal panel used in the present invention. 
           [0045]      FIG. 10D  is a sectional view of a liquid-crystal panel used in the present invention. 
           [0046]      FIG. 10E  is a sectional view of a liquid-crystal panel used in the present invention. 
           [0047]      FIG. 10F  is a sectional view of a liquid-crystal panel used in the present invention. 
           [0048]      FIG. 10G  is a sectional view of a liquid-crystal panel used in the present invention. 
           [0049]      FIG. 10H  is a sectional view of a liquid-crystal panel used in the present invention. 
           [0050]      FIG. 101  is a sectional view of a liquid-crystal panel used in the present invention. 
           [0051]      FIG. 11  is a sectional view of a lighting apparatus of the present invention placing a liquid-crystal panel slanted against a LED (light-emitting diode) substrate. 
           [0052]      FIG. 12  is a sectional view of a lighting apparatus of the present invention placing two liquid-crystal panels slanted in opposite directions. 
           [0053]      FIG. 13A  is a plan view of an example of an electrode of a liquid-crystal panel used in the present invention. 
           [0054]      FIG. 13B  is a plan view of an example of an electrode of a liquid-crystal panel used in the present invention. 
           [0055]      FIG. 13C  is a plan view of an example of an electrode of a liquid-crystal panel used in the present invention. 
           [0056]      FIG. 14A  is a plan view of an example of an electrode of a liquid-crystal panel used in the present invention. 
           [0057]      FIG. 14B  is a plan view of an example of an electrode of a liquid-crystal panel used in the present invention. 
           [0058]      FIG. 15A  is a sectional view showing an example of an electrode of a liquid-crystal panel of the present invention. 
           [0059]      FIG. 15B  is a sectional view showing an example of an electrode of a liquid-crystal panel of the present invention. 
           [0060]      FIG. 15C  is a sectional view showing an example of an electrode of a liquid-crystal panel used in the present invention. 
           [0061]      FIG. 16A  is a plan view of an example of an LED used in the present invention. 
           [0062]      FIG. 16B  is a plan view of an example of a liquid-crystal panel used in the present invention. 
           [0063]      FIG. 16C  is a sectional view showing an example of an electrode of a liquid-crystal panel of the present invention. 
           [0064]      FIG. 16D  is a sectional view showing an example of an electrode of a liquid-crystal panel of the present invention. 
           [0065]      FIG. 16E  is a sectional view showing an example of an electrode of a liquid-crystal panel of the present invention. 
           [0066]      FIG. 16F  is a sectional view showing an example of an electrode of a liquid-crystal panel used in the present invention. 
           [0067]      FIG. 17A  is a plan view showing an example of a liquid-crystal panel of the present invention. 
           [0068]      FIG. 17B  is a sectional view showing an example of an electrode of a liquid-crystal panel used in the present invention. 
           [0069]      FIG. 17C  is a sectional view showing an example of an electrode of a liquid-crystal panel of the present invention. 
           [0070]      FIG. 18A  shows an example of a voltage that is applied to the electrodes of a liquid-crystal panel of the present invention. 
           [0071]      FIG. 18B  shows an example of a voltage that is applied to the electrodes of a liquid-crystal panel of the present invention. 
           [0072]      FIG. 18C  shows an example of a voltage that is applied to the electrodes of a liquid-crystal panel of the present invention. 
           [0073]      FIG. 18D  shows an example of a voltage that is applied to the electrodes of a liquid-crystal panel of the present invention. 
           [0074]      FIG. 19A  explains an example of a voltage that is applied to the electrodes of a liquid-crystal panel of the present invention. 
           [0075]      FIG. 19B  explains an example of a voltage that is applied to the electrodes of a liquid-crystal panel of the present invention. 
           [0076]      FIG. 20A  is a sectional view of a lighting apparatus of the present invention placing liquid-crystal panels of different functions in layer. 
           [0077]      FIG. 20B  is a sectional view of a lighting apparatus of the present invention placing liquid-crystal panels of different functions in layer. 
           [0078]      FIG. 20C  is a sectional view of a lighting apparatus of the present invention placing liquid-crystal panels of different functions in layer. 
           [0079]      FIG. 20D  is a sectional view of a lighting apparatus of the present invention placing liquid-crystal panels of different functions in layer. 
           [0080]      FIG. 20E  is a sectional view of a lighting apparatus of the present invention placing liquid-crystal panels of different functions in layer. 
           [0081]      FIG. 21A  is a sectional view of an example of a liquid-crystal panel of the present invention. 
           [0082]      FIG. 21B  is a sectional view of an example of a liquid-crystal panel of the present invention. 
           [0083]      FIG. 21C  is a sectional view of an example of a liquid-crystal panel of the present invention. 
           [0084]      FIG. 21D  is a sectional view of an example of a liquid-crystal panel of the present invention. 
           [0085]      FIG. 21E  is a sectional view an example of a liquid-crystal panel of the present invention. 
           [0086]      FIG. 21F  is a sectional view of an example of a liquid-crystal panel of the present invention. 
           [0087]      FIG. 22A  is a sectional view of an example of a liquid-crystal panel of the present invention. 
           [0088]      FIG. 22B  is a sectional view of an example of a liquid-crystal panel of the present invention. 
           [0089]      FIG. 22C  is a sectional view of an example of a liquid-crystal panel of the present invention. 
           [0090]      FIG. 23  is a sectional view of an example of a liquid-crystal panel of the present invention. 
           [0091]      FIG. 24  is a sectional view of a bulb-shaped lighting apparatus of the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0092]    With reference to  FIG. 1B , the structure of an LED lighting apparatus of the present invention is described in detail. The lighting apparatus in accordance with an embodiment of the present invention includes: LEDs (light-emitting diodes)  2  which is mounted on a substrate  1 , a liquid crystal panel  4 , an LED drive circuit  12 , a remote control sensor  13 , and a liquid-crystal drive circuit  14 . The LED drive circuit  12 , the remote-control sensor  13 , and the liquid-crystal drive circuit  14  are connected to a commercial power supply  15  for domestic use. That is, the LED drive circuit and the liquid-crystal drive circuit are provided with voltages from a common commercial power supply. Transparent electrodes  42  are connected to the liquid-crystal drive circuit  14 . The LEDs (light-emitting diodes)  2  are connected to the LED drive circuit  12 . Embedding a human sensor in the lighting apparatus in accordance with an embodiment of the present invention enables to detect automatically areas where human is present and thus to provide comfortable and energy-saving lighting. 
         [0093]    The liquid-crystal panel  4  is composed by sealing a liquid crystal material  43  between two parallel glass substrates  41  where individual electrodes  42  consisting of transparent electrical-conductive films such as ITO are provided. When several volts are applied to the electrodes  42 , the direction of liquid crystal molecules  400  is changed to vary the optical characteristics. Herein the optical characteristics include the transmittance rate, refraction rate and attenuation rate of light. 
         [0094]    According to an embodiment of the present invention, the liquid-crystal drive circuit can change the modes of optical characteristics of the liquid-crystal panel as desired. For example, light transmittance and light refraction can be varied in a desired value. 
         [0095]    The detail will be described later. Thereby illumination light from the lighting apparatus can be varied in a desired mode. Moreover, as described in detail below, according to the present invention, the form and structure of the electrodes of a liquid-crystal panel can be made in various modes. It also enables light from the lighting apparatus to vary in a desired mode. 
         [0096]    The LED (light-emitting diode)  2  with a single p-n junction will be operated at several volts. Since both an LED (light-emitting diode) and a liquid-crystal panel are basically operated at several volts, thus the coherence between the electric circuits for them is considerably high. Therefore, both of the electric circuits can be integrated. 
         [0097]    Even when a plurality of LEDs (light-emitting diode) are connected in serial and/or in parallel for high output, the drive voltage will be approximately 10 to 15 volts. Also, some liquid-crystal panels operate at approximately 10 to 15 volts. Thus, coherence between LEDs and liquid-crystal panels is considerably high as electric components. 
         [0098]    With reference to  FIG. 1C and 1D , the present invention is described. For a liquid-crystal panel to be used for an embodiment of this invention, nematic liquid crystals are used, and the distance between the electrodes of the panel is 4 microns. As shown in  FIG. 1C , when zero volt is applied to a liquid-crystal panel to be used in an embodiment of this invention, the direction of liquid crystal molecules  400  is almost parallel to the electrode surface, resulting in not passing incident light  3  much. As shown in  FIG. 1D , increase in supply voltage changes the direction of the liquid-crystal molecules  400 , and the direction of molecules becomes able to pass the light  3  and becomes almost transparent at 5 voltages. Such characteristics, however, may greatly vary depending on the treatment of a liquid-crystal substrate and on the liquid-crystal materials. 
         [0099]    At present an application of liquid crystals in wide use is a display, which can regulate the optical transmission of fine pixels from complete zero to 100 percent. In this present invention, only optical transmission, reflection, and scattering in some range for a wide area are required, thus the structure of a liquid-crystal panel is considerably simple for easy production at a low cost. 
         [0100]      FIG. 2A  shows an embodiment of the present invention, in which a liquid-crystal panel acts as a concave lens by making micro-lenses or Fresnel structures in the electrodes of a liquid-crystal panel. In this embodiment, the liquid-crystal panel  4  that acts as a lens is positioned in parallel to the LED substrate  1  and thus light of high directionality  3  from an LED (light-emitting diode)  2  is scattered to generate light such as  5 , in a wide area. A liquid-crystal panel that acts as a convex lens with the perforated structure or the Fresnel structure of the electrodes can converge the light emitted from an LED (light-emitting diode) to provide a lighting apparatus that concentrates bright light in local. 
         [0101]    In the embodiment of the present invention shown in  FIG. 2B , a lens structure  41 A where liquid crystal panel acts as a concave lens is formed on a glass substrate  41 . In this embodiment of the present invention shown in  FIG. 2C , a region  41 B without electrode is formed on a glass substrate  41 . In the embodiment of the present invention shown in  FIG. 2D , a micro lens structure  41 C where liquid-crystal panel acts as a convex lens is formed on a glass substrate  41 . In the embodiment of the present invention shown in  FIG. 2E , a Fresnel lens  41 D is formed on a glass substrate  41 . 
         [0102]    In the embodiment of the present invention shown in  FIG. 2F , a plurality of micro-lenses or Fresnel lenses are formed on a glass substrate  41 . As for these lens structure, a relatively large lens structure underneath LEDs or very small micro-lens array can be made according to the requirement. 
         [0103]      FIG. 3A  shows an embodiment of the present invention in which microcapsulated liquid crystals dispersed in polymer are used for the panel. At zero volt to the liquid-crystal panel, the direction of the microcapsulated liquid crystals are at random, so that the light from LEDs (light-emitting diodes) is reflected on the liquid-crystal panel  4  and scattered as light  5 , leading to indirect lighting. Liquid-crystal panels with such properties are so far used as optical blinds. 
         [0104]    With reference to  FIG. 3B and 3C , the present invention is described. In a liquid-crystal panel of this present invention, the distance between the electrodes is 10 micron, and the size of a microcapsule  401  containing liquid crystals is about one microns; a plurality of the microcapsules are dispersed in polymer  402 . As shown in  FIG. 3B , at zero volt, a liquid-crystal panel of this present invention blocks light from LEDs, to be scattered and reflected for indirect lighting. As shown in  FIG. 3C , at 5 volts, the liquid-crystal panel passes the light from LEDs through and the panel becomes transparent to give bright lighting. 
         [0105]    In addition, a reflective liquid-crystal panel with polymer-dispersed liquid crystals used for mobile phone displays can be employed for this invention. At zero volts, it reflects and scatters light from LEDs, whereas it passes the light through at 5 volts to give brighter lighting. 
         [0106]    Moreover, a liquid-crystal panel with polymer-dispersed liquid crystals, in which electrodes are of a plurality of concentric circles under LEDs can provide lens effects caused by light diffraction. Therefore, such a liquid-crystal panel concentrates or disperses further light from LED for regulating a wide range of lighting. 
         [0107]      FIG. 4  illustrates an apparatus that provides complex illumination by giving different characteristics to a liquid-crystal panel with a plurality of sections, not a uniform liquid crystal panel. In  FIG. 4 , the right part of the liquid-crystal panel  4 B, consisting of polymer-dispersed liquid crystals, scatters light  3  from LEDs (light-emitting diodes) as light  5 A or  5 B, whereas the left part of the liquid-crystal panel  4 A, having a function of a concave lens, passes and disperses the light from LED (light-emitting diodes)  3  as  5 C, making a left half of a room bright and a right half with indirect lighting. 
         [0108]      FIG. 5  is an embodiment of the present invention in which liquid-crystal panels of different functions are alternately positioned by sectioning. This is a lighting apparatus that provides mild illumination in a large area. By regulating voltages applied to sectioned liquid-crystal panels of different functions, lighting quality in a large area can be regulated. Also, a lighting apparatus in which the same functional liquid-crystal panels are divided into a plurality of sections, it can regulate lighting quality by regulating individual sections. 
         [0109]      FIG. 6  shows an embodiment of the present invention in which a plurality of liquid crystals of different functions are positioned in layers. The first liquid-crystal panel  4 B is a polymer-dispersed liquid-crystal panel and the second liquid-crystal panel  4 A is a liquid-crystal panel having a function of a concave lens. When a voltage is applied to the first liquid-crystal panel, it will be transparent to light, and an appropriately dispersed lighting can be provided by regulating a voltage to the second liquid-crystal panel. Also, reducing the voltage or applying zero volt to the first liquid-crystal panel, indirect lighting can be obtained. 
         [0110]      FIG. 7  shows an application of the present invention to a bulb-shaped LED lamp that is recently on market. A liquid-crystal panel  4  having a function of a concave lens is positioned away from the light-emitting substrate  1  of LEDs (light-emitting diodes) array  2  in the glass container  6 . By regulating voltage to the liquid-crystal panel, spreading light  5  can be obtained. 
         [0111]      FIG. 8A  illustrates a similar bulb-shaped LED lamp of an embodiment of the present invention in which two liquid-crystal panels  4 A and  4 B of different characteristics are layered. The structure of  FIG. 6  is applied to a bulb shaped LED lamp, thereby various types of lighting can be obtained. For a bulb-shaped lamp of  FIG. 8B , two liquid-crystal panels  4 A and  4 A of different characteristics are layered. In this embodiment of the present invention, however, liquid panels  4 A and  4 B are curved in the same shapes of the bulb. That is, the liquid panels  4 A and  4 B have hemispheric shape. 
         [0112]      FIG. 9  shows a sectional view of a lighting apparatus of the present invention that is installed on a ceiling. Light of high directionality  3  from LEDs (light-emitting diode)  2  mounted on a hemicylinder substrate I inside a cover  8  is regulated to mild light  5  by a hemicylinder liquid-crystal panel  4  positioned in front of the LEDs  2 . This hemicylinder liquid-crystal panel can be easily produced using a liquid-crystal film. 
         [0113]    In the examples of  FIG. 9  and  FIG. 8B , a curved liquid-crystal film panel is used. For such liquid-crystal panels, a plastic substrate may be used instead of a glass substrate. 
         [0114]      FIG. 10A  is a plan view of a liquid-crystal panel of the present invention that scatters light by forming a mesh electrode (consisting of electrode section  42 A and non-electrode section  42 B), not using a micro-lens described in the embodiment 1, to cause nonuniformity in an electric field distribution and to generate regular variation in the optical properties of the liquid-crystal. 
         [0115]      FIG. 10B  is a sectional view of the liquid panel shown in  FIG. 10A . The size of the non-electrode section  42  is L, and the distance between two electrodes  42 A and  42 B is d. In  FIG. 10B , the non-electrode section  41 B of size L is formed on the electrode  42 A on the top side. On the other hand, the bottom side electrode  42 B is evenly formed on the glass substrate  41 .  FIGS. 10C to 10F  show examples for various ratios of Lid: size L of non-electrode section  41 B to size d between two electrodes  42 A and  42 B. 
         [0116]    In the examples in  FIG. 10C  and  FIG. 10D , size d between two electrodes  42 A and  42 B is comparatively larger and equivalent to size L. In  FIG. 10C , voltage to be applied between two electrodes is V=0. In this case, light  3  from an LED (light emitting diodes) is mostly reflected and partially transmitted to be scattered, thereby a room becomes dark. In  FIG. 10D , when voltage V=V is applied between the two electrodes, light  3  from an LED (light emitting diodes) is transmitted where electrodes are built, and it is mostly reflected and partially transmitted where the electrodes are not built, thereby the room is bright by indirect lighting due to the transmitted light and the reflected light. 
         [0117]    In the examples of  FIG. 10E  and  FIG. 10F , the size d between two electrodes  42 A and  42 B is comparatively smaller and sufficiently smaller than the size L. In  FIG. 10E , voltage between the two electrodes is V=0. In this case, most light from LEDs (light emitting diodes) reflects, thereby the room becomes dark. In  FIG. 10F , voltage V=V is applied between the two electrodes. Light  3  from LEDs (light emitting diodes) is transmitted where electrodes are built, and is reflected where the electrodes are not built, thereby the room will becomes bright by indirect lighting due to the transmitted light and the reflected light. 
         [0118]      FIG. 10G  to  FIG. 10I  show examples in which two electrodes  42 A and  42 B are completely formed and non-electrode section is not provided. In these examples the gap between the electrodes is narrow in a partial region of a single electrode of either  42 A or  42 B, and the gap size d between the electrodes is normal in other regions. Therefore, in these examples, a region of narrow gap between two electrodes is provided instead of a section of no electrode. The size of the region of narrow gap d between the two electrodes is L. 
         [0119]    In the examples of  FIG. 10G  and  FIG. 10H , each of two electrodes  42 A and  42 B is evenly provided on the internal surface of the glass substrate  41 . However, one of the glass substrates  41  is partly thicker. In the area  41 E where the thickness of the glass substrate  41  is greater, the thickness of liquid-crystal  43  and the gap between two electrodes are smaller. 
         [0120]    In  FIG. 10G , voltage to be applied between two electrodes is V=0. In this case, most light  3  from an LED (light emitting diode) reflects, thereby a room becomes dark. In  FIG. 10H , voltage V=V 0  is applied between the two electrodes. Then, most light  3  from an LED (light emitting diode) is transmitted in the area where the gap between electrodes is narrow, thereby a room is bright by indirect lighting due to the transmitted light and the reflected light. 
         [0121]    In the example of  FIG. 10I , an electrode  42 A of upper side is formed on the internal surface of the glass substrate  41  of the top side, whereas an electrode  42 B is formed in the interior of a glass substrate  42  of the bottom side. The thickness of the two substrates and the thickness of the liquid-crystal  43  inserted between them are constant, but the gap between the two electrodes is not constant. In this case, when voltage V=0 is applied between the two electrodes, most light  3  from LED (light emitting diodes) is transmitted in the area where the gap between the electrodes is narrow, thereby a room becomes bright by indirect lighting due to the transmitted light and the reflected light. 
         [0122]    In a liquid-crystal panel which has a function as a lens, as is already described, a lens with such a distinctive distance of focal points as is shown in prior art references is not needed. It may function as an indefinite light focus or diffusion. Therefore, as in an embodiment of the present invention, nonuniform structure of electrodes causes a nonuniform electric field. As a result, optical properties such as the refractive index of liquid-crystal materials become ununiform to cause light convergence or diffusion. 
         [0123]      FIG. 11  is an embodiment of the present invention wherein a liquid-crystal panel is tilted against the LED (light-emitting diode) substrate. By tilting the liquid-crystal panel, light  3  from an LED (light-emitting diode) reflects on the surface of the liquid-crystal panel  4  as lights  5 A. Also the transmitted light becomes lights as  5 B and is scattered as lights  5 C. Light  3  from an LED (light-emitting diode) spreads in an extremely large area to illuminate a space effectively. 
         [0124]      FIG. 12  is an embodiment of the present invention wherein each of the two liquid-crystal panels  4 A and  4 B are tilted in different directions, thereby wide-area illumination is possible by balancing the right and left spaces. Furthermore, with a plurality of such liquid-crystal panels, a great variety of lighting is made possible by controlling electric signals for individual liquid-crystal panels. 
         [0125]      FIG. 13A  to  FIG. 13C , show other forms of an embodiment shown in  FIG. 10A , in which examples of the various forms of the electrode structure are shown. These electrode structures include an electrode section  42 A and a non-electrode section  41 B. The electrodes of this example can be obtained by first evenly forming transparent electrodes on a glass substrate and then eliminating them in sections with given forms. The non-electrode section  41 B can have a form of a circle, a triangle, or others of various sizes. The pattern of the transparent electrodes can be produced by means of known lithography technologies. LEDs (light-emitting diodes) can be positioned as desired; for example, LEDs (light-emitting diode) can be positioned immediately above a circular non-electrode section  41 B of relatively large size. 
         [0126]      FIG. 14A  and  FIG. 14B  further show the examples of electrode structures in various forms. These electrode structures individually include a single electrode section  42 A and a single non-electrode section  41 B. The electrode of this example can be obtained by forming a transparent electrode in the area in given form on a glass substrate. The positioning LEDs (light-emitting diodes) directly above the area of relatively large electrode section  42 A is favorable. 
         [0127]    With reference to  FIG. 15A  to  FIG. 15C , the detail of electrode structures will be described. A liquid-crystal panel  4  is composed of two parallel glass substrates  41  provided with a single electrode  42 A and a single electrode  42 B made of a transparent conductive film such as ITO, wherein a liquid crystal material  43  is sealed. 
         [0128]    In these examples, an electrode  42 A on the top side and an electrode  42 B on the bottom side are control electrode and common electrode respectively. The control electrode  42 A on the top side includes a plurality of electrodes that are separated one another. That is, the common electrode  42 A is separated by the non-electrode section  41 B. Of a plurality of control electrodes  42 A, a desired voltage is applied between a given electrode and the common electrode  42 B on the bottom side. 
         [0129]    In the example of  FIG. 15A , a common electrode  42 B is evenly formed in the internal surface of a glass substrate  41  on the bottom side. In the example of  FIG. 15B , a common electrode  42 B and a control electrode  42 A have the same form and both are positioned on the corresponding places. In the example of  FIG. 15C , a common electrode  42 B and a control electrode  42 A have the same form and both are positioned on different places each other. As described in these examples, the relative position of a common electrode  42 B and a control electrode  42 A can be freely set. 
         [0130]    The electrodes that are shown in  FIG. 13A  to  FIG. 13C  and  FIG. 14A  to  FIG. 14B  are control electrodes, but a common electrode corresponding to the control electrodes can be arbitrarily positioned. Provided that control electrodes are arbitrarily positioned, the relative positional relation between a common electrode  42 B and a control electrode  42 A varies a direction of liquid crystal molecules, resulting in changing the light intensity and the characteristics of transmitted light. 
         [0131]      FIG. 16A  shows the plan structure of LEDs (light-emitting diodes)  2  mounted on a substrate  1 .  FIG. 16B  shows the form of a control electrode of a liquid-crystal panel that is positioned under these LEDs (light-emitting diodes)  2 . The control electrodes  42 A consists of an inside circular section  42 A- 1  and an outside ring section  42 A- 2 . The circular section and the ring section, which are separated from each other via a non-electrode section  41 B, are independently supplied with a voltage. 
         [0132]    With reference to  FIG. 16C  and  FIG. 16F , the operation of the LED lighting apparatus shown in  FIG. 16A  and  FIG. 16B  is described.  FIG. 16C  shows the sectional structure of the LED (light-emitting diode)  2  mounted on the substrate  1 .  FIG. 16D  to  FIG. 16F  show the sectional structures of the LED (light-emitting diode)  2  that is mounted on the substrate  1 , and the liquid-crystal panel  4 . 
         [0133]      FIG. 16D  shows the case of zero volt applied. Light from an LED (light-emitting diode)  2  is scattered by the liquid-crystal panel and it almost never passes through.  FIG. 16E  shows the case of voltage applied to both a circular section  42 A- 1  and a ring section  42 A- 2  of a control electrode, wherein light from an LED (light-emitting diode)  2  passes through the liquid-crystal panel.  FIG. 16F  shows the case when voltage is applied to a circular section  42 A- 1  and zero volt is applied to a ring section  42 A- 2 . Light from an LED (light-emitting diode)  2  is passed through the circular section  42 A- 1  and is scattered in the ring section  42 A- 2 . 
         [0134]      FIG. 17A  shows LEDs (light-emitting diodes)  2  that are mounted on a substrate  1 . The LEDs  2  are positioned in ring.  FIG. 17B  shows the case when zero volt is applied and light from LEDs is scattered on the liquid-crystal panel.  FIG. 17C  shows the case an applied voltage is not zero and light from LEDs is passed through the liquid-crystal panel. 
         [0135]      FIG. 18A  shows voltages to be applied to a normal liquid-crystal panel. In a liquid-crystal panel to be used in a display device, positive and negative voltages are alternately applied.  FIG. 18B  and  FIG. 18C  show the examples of voltages that are applied to a liquid-crystal panel to be used in an LED lighting apparatus in accordance with the present invention. In this embodiment, a positive voltage is applied for time t v  and then zero volt is applied for time t 0 . Next a negative voltage is applied for time t v  and zero voltage is applied for time t o . These applications are repeated. A number of applications of positive voltages in one second is hereafter called “frequency”. Frequency can be from several tens to several hundred cycles. 
         [0136]    The ratio of time that either a positive or a negative voltage is applied to a single cycle T is called “duty”. For example, the duty is 1 in  FIG. 18A ; 0.5 in  FIG. 18B ; and 0.2 in  FIG. 18C . Setting certain values of duty and frequency enables a lighting apparatus to emit a desired amount of light.  FIG. 18D  shows when zero volt is applied. Light from LEDs is scattered by a liquid-crystal panel. 
         [0137]      FIG. 19A  shows a relationship between a voltage to be applied to a liquid-crystal panel and the amount of light transmitted. When the voltage is V 0 , the light transmitted is very small, whereas when the voltage is increased to V M , the light transmitted increases. When the voltage is greater than V S  the light transmitted becomes maximum. 
         [0138]      FIG. 19B  shows an example of voltage applied to a liquid-crystal panel of the lighting apparatus of the present invention. In this embodiment, a positive voltage V H  is applied for time t H  and a positive voltage V L  for time t L . Next a negative voltage V H  is applied for time t H  and a negative voltage V L  is applied for time t L . These applications are repeated. One cycle is given by time (t H +t L )×2. V H  and V L  can be of any values. High voltage V H  can be V S  in  FIG. 19A  and low voltage V L  can be V 0  or V M  in  FIG. 19A . Thus, this case, most of the light from LEDs (light-emitting diodes)  2  is passed through for a time t H  and the light from LEDs (light-emitting diodes) is partly passed through and the most of the light is scattered for time t L . The explanation is made on a case that the transparency of liquid-crystal panel is changed with the change of applied voltage. In general, controlling an applied voltage varies the optical characteristics of liquid crystal. Herein the optical characteristics include light transmission rate, light refraction rate, and light attenuation rate. In the present invention, controlling an applied voltage varies the optical characteristics of liquid crystal in a desired mode, thereby illumination light from an LED lighting apparatus can be varied in a desired mode. 
         [0139]    The explanation is made with reference to  FIG. 19A  and  FIG. 20A  to  FIG. 20E .  FIG. 6  shows an example of two layered liquid-crystal panels. In these embodiments, the liquid-crystal panel has a similar structure to the layered two panels. The liquid-crystal panel of the present embodiment also has three parallel glass substrates  411 ,  412 , and  413 . On the interior surface of the glass substrate  411  on the top, a first control electrode  421  is formed; on the both sides of the glass substrate  412  in the middle, common electrodes  422  and  423  are formed; and on the interior surface of the glass substrate  413  on the bottom, a second control electrode is formed. Between these three parallel glass substrates, liquid crystals  431  and  432  are individually sealed. 
         [0140]    The first liquid-crystal panel is composed of the first control electrode  421  and the common electrode  422 , and the second liquid-crystal panel is composed of the second control electrode  424  and the common electrode  423 . Voltage to the first liquid-crystal panel is V 1 , and voltage to the second liquid-crystal panel is V 2 . 
         [0141]      FIG. 20B  shows the case when both applied voltages to two liquid-crystal panels are zero, where V 1 =V 2 =0. In this case, most of the light  3  from the LEDs (light-emitting diodes)  2  is reflected and is scattered.  FIG. 20C  shows the case that voltage V 1  applied to the first liquid-crystal panel is V 1 =V S  and voltage applied to the second liquid-crystal panel is either V 2 =0 or V 0 . In this case, most of the light  3  from the LEDs (light-emitting diodes)  2  is passed through the first liquid-crystal panel and most of the passed light is reflect on the second liquid-crystal panel and is scattered. 
         [0142]      FIG. 20D  show the case when V M  volts are applied to two liquid crystal panels individually. That is, V 1 =V 2 =V M . In this case, about half of the light  3  from the LEDs (light-emitting diodes)  2  passes through the first liquid-crystal panel, and half of the light that have passed through passes through the second liquid-crystal panel. Thus, changing each of the voltages applied to the two liquid-crystal panels can provide desired illuminating light. 
         [0143]      FIG. 20E  further shows a different example of a layered liquid-crystal panel of the present invention. In the liquid-crystal panel of this example, the control electrodes shown in  FIG. 15A  to  FIG. 15C  are used. Compared with the example shown in  FIG. 20A , the first control electrode  421  and the second control electrode  422  are of separate type. The control electrodes  421  and  423  are separated into a plurality of electrodes by non-electrode sections  411 B and  413 B respectively; thereby a voltage can be independently applied to each of the electrodes. 
         [0144]      FIG. 21A  shows the sectional structure of a different example of a liquid-crystal panel. The liquid crystal panel of this example comprises two glass substrates  41  and liquid crystals  43  that are sealed between the two glass substrates. Space between the glass substrates  41  is divided into a plurality of areas by separators  44 . In each area different liquid crystal  43  is sealed. Either the common electrode  421  or the control electrodes  422  is provided on the internal surface of the glass substrates  41 . One of the control electrodes is provided for each area.  FIG. 21B  shows a plan structure of the control electrodes of this example. A desired voltage is applied between a given one of the plurality of electrodes and the common electrode  421 . In the liquid crystal panels shown in  FIG. 15A  to  FIG. 15C , only a single type of liquid crystal panel can be used. However, in the liquid-crystal panel of this example, different types of liquid crystal can be used.  FIG. 21C  shows a plan structure of the liquid-crystal panel of this example. The liquid-crystal panel of this example has functions equivalent to those of the plane combination of different panels. In the example of  FIG. 21B , the liquid-crystal panel has functions equivalent to those of different liquid-crystal panels array in stripe. In the example of  FIG. 21C  the liquid-crystal panel has functions equivalent to those of different liquid-crystal panel array in tile. 
         [0145]      FIG. 21D  to  FIG. 21F  are other examples of a liquid-crystal panel unit to be embedded in the liquid-crystal panel shown in  FIG. 21B  or  FIG. 21C . In these examples, liquid-crystal panels with different structures of the control electrodes are combined. In the examples of  FIG. 21D  and  FIG. 21E  the control electrodes on the top have the Fresnel structure, whereas in the example of  FIG. 21F  a normal plain electrode is used. In the examples of  FIG. 21D  and  FIG. 21E , the direction of the Fresnel lenses are different from each other. Embedding these liquid-crystal panels, individual liquid-crystal panels  4 A and  4 B in  FIG. 21C  can provides desired illuminating light. 
         [0146]    With reference to  FIG. 22A  to  FIG. 22C , further different examples of the liquid crystal-panel of the present invention are described.  FIG. 22A  shows a sectional structure of the liquid-crystal of this example. The liquid crystal panel of this example can be similar to the panel of  FIG. 21A . In this example, the guest-host liquid crystal  43  is used. Pigments which have different absorption colours are added to the guest-hot liquid crystal  43 . That is, in this example the guest-host liquid crystal  43  to which different pigments are added is used instead of different types of liquid crystal. In  FIG. 22B  liquid crystals that provide light of one of three pigment colors: red, green, and blue are combined. The first liquid crystal  431  provides red light, the second liquid crystal  432  green light, and the third liquid crystal  433  blue light.  FIG. 22C , thus, shows a plan structure of the liquid-crystal panels that provides light of one of the three pigment colours: red, green, and blue. 
         [0147]      FIG. 23  shows an example of a lattice-shaped liquid-crystal panel. In the liquid-crystal panel in accordance with an embodiment of the present invention, a plurality of either square liquid-crystal panels or rectangular liquid-crystal panels are arrayed. As shown in  FIG. 23 , the space between the two substrates is divided into a plurality of regions by a separator  44 . Control electrode  423  is placed on each region. A plurality of square liquid-crystal panels or rectangular liquid-crystal panels are formed herewith. The size of a single liquid-crystal panel consisting of the liquid-crystal panel in the present invention can be very small, for example, it can be less than 1 cm such as several millimeters. 
         [0148]      FIG. 24  shows that either of the liquid-crystal panels shown in  FIG. 21A  or in  FIG. 22A  is applied to the bulb-type LED lamp of  FIG. 7 . Desired voltages can be independently applied to each panel. 
         [0149]    Several embodiments of the present invention are described above; however, the present invention is not limited to them. Therefore, those skilled in the art can easily understand that the present invention can be applied widely within the scope of the invention claims. 
       INDUSTRIAL APPLICABILITY 
       [0150]    An LED lighting apparatus of the present invention is industrially easy-producible and in wide demand including home and offices, so its industrial value is very high. In particular, liquid-crystal panels for displays require highly sophisticated technologies such as alignment for polarizing plates and liquid crystal substrates. A liquid-crystal panel of the present invention, however, does not necessarily require such polarizing plates or alignment, and its manufacturing is extremely easy. Therefore, the LED lighting apparatus can be produced at low cost for higher potential popularization. 
       LIST OF REFERENCE SYMBOLS 
       [0151]      1 : LED (light-emitting diode) substrate,  2 : LED (light-emitting diode),  3 : light from LED (light-emitting diode),  4 ,  4 A, and  4 B: liquid-crystal panel,  5 ,  5 A,  5 B,  5 C: light from liquid-crystal panel,  6 : glass container of a light bulb,  7 : base of a light bulb,  8 : cover,  13 : remote-control sensor,  14 : liquid-crystal drive circuit,  12 : LED drive circuit,  15 : commercial power supply,  41 : glass substrate,  42 : transparent electrode,  43 : liquid crystal,  41 A: convex lens section,  41 B: hole,  41 C: concave lens section,  41 D: Fresnel lens section,  400 : liquid crystal molecule,  401 : microcapsule

Technology Classification (CPC): 5