Plane-shaped lighting device and a display using such a device

• US 6,415,531 B1
• Filed: 02/22/2000
• Issued: 07/09/2002
• Est. Priority Date: 05/23/1995
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Azuma, Hitoshi, Wada, Yasuhiro, Minematsu, Hiroshi, Kimoto, Masahiko, Tominaga, Nobuyuki, Funakoshi, Takahiro, Ohtsuki, Terukazu
• Primary Examiner(s): Sember, Thomas M.
• Application Number:
  US09/510,195
• Time in Patent Office: 868 Days
• Field of Search: 362/31, 362/26, 362/812, 362/249, 362/252, 362/235, 362/330, 362/339, 362/800, 362/327, 362/328, 362/329
• US Class Current: 36/31
• CPC Class Codes: G02B 6/0021 for housing at least a part of the light source, e.g. by forming holes or recesses
• CPC Class Codes: G02B 6/0023 provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/0043 provided on the surface of the light guide
• CPC Class Codes: G02B 6/006 to produce indicia, symbols, texts or the like
• CPC Class Codes: G02B 6/0061 to provide homogeneous light output intensity
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• CPC Class Codes: G09F 13/04 Signs, boards or panels, illuminated from behind the insignia
• CPC Class Codes: G09F 13/0472 Traffic signs
• CPC Class Codes: G09F 13/0481 Signs, boards or panels having a curved shape
• CPC Class Codes: G09F 13/22 electroluminescent electroluminescent light sources per se H05B33/00
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: Y10S 362/80 Light emitting diode
• CPC Class Codes: Y10S 362/812 Signs

Abstract

A plane-shaped lighting device has a light-directing plate and a light source that is placed in contact with or in the proximity of the light-incident surface of the light-directing plate, and the light source is constituted of a plurality of LED lamps each of which has an LED chip for emitting light and a semispherical lens for directing the light from the LED chip into the light-directing plate. Here, the distance from the LED chip to the top of the semispherical lens is set to be 1.8 times as long as the radius of curvature of the semispherical lens. This arrangement allows the light emitted from the LED chip to be efficiently incident on the light-incident surface of the light-directing plate, thereby improving the light-incidence efficiency to the light-directing plate. Further, the application of this plane-shaped lighting device to display devices makes it possible to improve the efficiency of light utilization, and consequently to provide thinner display devices with high visibility.

Claims

1. A plane-shaped lighting device comprising:

a light-directing plate made of a plate-shaped light-transmitting member; and

a light source that is placed close to or in contact with one side face of the light-directing plate,

wherein;

light, which has been emitted from the light source and made to be incident on a light-incident surface on the one side face of the light-directing plate, is taken out from a plane section of the light-directing plate; and

a plurality of light-takeoff bodies, each having a recessed shape or a protruding shape, are provided on the plane section of the light-directing plate in a direction parallel to the one side face and in at least two directions that intersect said direction, the light-takeoff bodies being arranged so that the density thereof increases as the distance from the light source increases, and so that each light-takeoff body has a smooth surface.

2. The plane-shaped lighting device as defined in claim 1, wherein each light-takeoff body is designed to have either of the following shapes:

a continuous-line shape, a discontinuous-line shape, and a shape made by combining these line shapes.

3. The plane-shaped lighting device as defined in claim 1, wherein each light-takeoff body consists of short lines that intersect one another at one point.

4. The plane-shaped lighting device as defined in claim 1, wherein the light source is provided with LED lamps each of which has an LED chip for emitting light and a semispherical lens that directs light from the LED chip to the inside of the light-directing plate, the LED lamp being designed so that the distance from a top of the semispherical lens to the LED chip is set to be not more than 1.8 times the radius of curvature of the semispherical lens.

5. The plane-shaped lighting device as defined in claim 1, wherein the light source is provided with LED lamps each of which has a reflection wall for directing light from an LED chip into the light-directing plate and a flat light-releasing surface.

6. A plane-shaped lighting device comprising:

a light-directing plate made of a plate-shaped light-transmitting member;

a light source that is placed close to or in contact with one side face of the light-directing plate,

so that light, which has been emitted from the light source and made to be incident on a light-incident surface on the one side face of the light-directing plate, is taken out from a plane section of the light-directing plate;

a plurality of light-takeoff bodies, each of which has a recessed shape or a protruding shape with a smooth surface, are provided on the plane section of the light-directing plate in a direction parallel to the one side face and the light-takeoff bodies, each of which has a curved line shape, are arranged so that the density thereof increases as the distance from the light source increases; and

wherein the LED lamps each of which has an LED chip for emitting light and a semispherical lens that directs light from the LED chip to the inside of the light-directing plate, each LED lamp being designed so that the distance from a top of the semispherical lens to the LED chip is set to be not more than 1.8 times the radius of curvature of the semispherical lens.

7. A plane-shaped lighting device comprising:

a light-directing plate made of a plate-shaped light-transmitting member;

a light source that is placed close to or in contact with one side face of the light-directing plate,

so that light, which has been emitted from the light source and made to be incident on a light-incident surface on the one side face of the light-directing plate, is taken out from a plane section of the light-directing plate;

a plurality of light-takeoff bodies, each of which has a recessed shape or a protruding shape with a smooth surface, are provided on the plane section of the light-directing plate in a direction parallel to the one side face and the light-takeoff bodies, each of which has a curved line shape, are arranged so that the density thereof increases as the distance from the light source increases; and

wherein the light source is provided with LED lamps each of which has a reflection wall for directing light from an LED chip into the light-directing plate and a flat light-releasing surface.

8. A plane-shaped lighting device comprising:

a light-directing plate made of a plate-shaped light-transmitting member;

a light source that is placed close to or in contact with one side face of the light-directing plate,

so that light, which has been emitted from the light source and made to be incident on a light-incident surface on the one side face of the light-directing plate, is taken out from a plane section of the light-directing plate;

a plurality of light-takeoff bodies, each of which has a recessed shape or a protruding shape with a smooth surface, are provided on the plane section of the light-directing plate, and the light-takeoff bodies, each of which is designed to have a spherical shape, are arranged so that the density thereof increases as the distance from the light source increases; and

wherein the light source is provided with LED lamps each of which has an LED chip for emitting light and a semispherical lens that directs light from the LED chip to the inside of the light-directing plate, the LED lamp being designed so that the distance from the top of the semispherical lens to the LED chip is set to be not more than 1.8 times the radius of curvature of the semispherical lens.

9. A plane-shaped lighting device comprising:

a light-directing plate made of a plate-shaped light-transmitting member;

a light source that is placed close to or in contact with one side face of the light-directing plate,

so that light, which has been emitted from the light source and made to be incident on a light-incident surface on the one side face of the light-directing plate, is taken out from a plane section of the light-directing plate;

a plurality of light-takeoff bodies, each of which has a recessed shape or a protruding shape with a smooth surface, are provided on the plane section of the light-directing plate, and the light-takeoff bodies, each of which is designed to have a spherical shape, are arranged so that the density thereof increases as the distance from the light source increases;

wherein the light source is provided with LED lamps each of which has a reflection wall for directing light from an LED chip into the light-directing plate and a flat light-releasing surface.