JPH0610982U - Planar light emitting unit - Google Patents

Abstract

(57) [Summary] [Object] To provide a planar light emitting unit which can be thinned by a simple manufacturing process. [Structure] A plurality of bare chip LEDs 15 are coated on one surface with transparent electrodes 21 and 2 using conductive adhesive sheets 13 and 14.
It is sandwiched by the transparent sheet members 11 and 12 on which 2 is formed. As a result, the transparent electrodes 21 and 22 are electrically and mechanically connected to the anode side electrode 23 and the cathode side electrode 24. Further, a diffusion plate 16 is sandwiched between the conductive adhesive sheets 13 and 14 to form a bare chip LED 15 in a planar shape.
Diffuse the light from. Further, the diffusion sheet 17 is provided on the upper surface of the transparent sheet member 11, and the reflection plate 10 is provided on the lower surface of the transparent sheet member 12 to emit planar light.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a planar light emitting unit, and more particularly to an LED (light emitting diode) type planar light emitting unit used for an illuminated switch, a liquid crystal backlight, and the like.

[0002]

[Prior art]

 As shown in FIG. 4, a conventional LED type planar light emitting unit is mounted with a plurality of discrete LEDs 42 on an LED board 41 by soldering and fixing the wires. Further, on the LED substrate 41, a reflection plate 43 for reflecting the light from the discrete LED 42, a light guide plate 44 for guiding and diffusing the light in a planar shape, and a diffusion for diffusing the light to become a light emitting surface. The sheet 45 and the like are provided. In addition, there is a device in which a bare chip LED is used instead of the discrete LED 22.

Further, there is a device using a bare chip LED as shown in FIG. That is, the silver paste 53 is applied to the surface of the electrode copper foil 52 formed on the LED substrate 51, and one electrode of the bare chip LED 54 is electrically connected via the silver paste 53. The other electrode of the bare chip LED 54 is connected and connected to another copper foil 55 on the LED substrate 51 by a wire 56 by a wire bonding method or the like. Also in this example, the light guide 57, the reflector 58, the diffusion sheet 59 and the like are appropriately combined, as in the planar light emitting unit of FIG.

[0004]

[Problems to be solved by the device]

 However, in the conventional planar light emitting unit, a light guide, a diffuser, a reflector, or the like is assembled on an LED substrate soldered with an LED, or a bare chip LED mounted on the LED substrate is soldered. Since the structure is such that wires are connected by wire bonding or the like, it is difficult to reduce the thickness. Further, it is necessary to connect a plurality of LEDs provided on the LED substrate one by one by soldering or wire bonding, which requires complicated work, and the manufacturing method is complicated and troublesome. It

An object of the present invention is to provide a planar light emitting unit that can be easily thinned and can be manufactured by a simple process.

[0006]

[Means for Solving the Problems]

 According to the present invention, a pair of transparent sheet members each having a transparent electrode formed on one surface thereof, a pair of conductive adhesive sheets, and a plurality of bare chip LEDs each having electrodes formed on an upper surface and a lower surface thereof are provided. By sandwiching the plurality of bare chip LEDs with the pair of transparent sheet members via the conductive adhesive sheet, the transparent electrodes formed on one of the pair of transparent sheet members and the upper surface of the plurality of bare chip LEDs are formed. So that the transparent electrodes formed on the other side of the pair of transparent sheet members and the electrodes formed on the lower surfaces of the bare chip LEDs are electrically connected. A planar light emitting unit characterized by the above is obtained.

[0007]

[Action]

 Since a transparent sheet member having a transparent electrode formed thereon, a conductive adhesive sheet, a bare chip LED and the like are pressure-bonded, a large number of bare chip LEDs can be electrically connected together. Therefore, the manufacturing method can be greatly simplified.

Further, since all the constituent elements except the bare chip LED can be formed in a sheet shape, it becomes possible to form a very thin planar light emitting unit.

[0009]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention. This planar light emitting unit has a pair of transparent sheet members 11 and 12, a pair of conductive adhesive sheets 13 and 14, and a plurality of bare chip LEDs 15. Further, the planar light emitting unit of this embodiment has a diffusion plate 16, a diffusion sheet 17, and a reflection plate 18.

Transparent electrodes 21 and 22 are formed on one surface of the transparent sheet members 11 and 12, respectively. As the transparent sheet members 11 and 12, for example, a resin transparent sheet such as a transparent polyester sheet or a resin transparent plate such as a transparent acrylic plate is used.

As the conductive adhesive sheets 21 and 22, for example, anisotropic conductive adhesive sheets are used. The conductive adhesive sheets 21 and 22 electrically and mechanically couple the transparent electrodes 21 and 22 with the upper and lower electrodes formed on the upper and lower surfaces of the bare chip LED 15 by thermocompression bonding or the like. The bare chip LED 15 is used as a light emitting body in this planar light emitting unit, and a plurality of bare chip LEDs 15 are provided on the same plane at arbitrary positions and intervals according to the brightness specifications of the planar light emitting unit.

The diffusing plate 16 is for guiding and diffusing light emitted from the bare chip LED 15 especially in the lateral direction, and is made of resin, for example. Similar to the bare chip LED 15, the diffusion plate 16 is fixed to the transparent sheet members 11 and 12 on the upper and lower surfaces by the conductive adhesive sheets 21 and 22. A light guide plate may be used instead of the diffusion plate 16. The diffuser plate 16 or the light guide plate may be appropriately used from a transparent light guide member to a diffuser plate mixed with a diffusing material depending on the brightness and the degree of diffusion of the planar light emitting unit.

The diffusion sheet 17 diffuses the light emitted from the upper surface of the bare chip LED 15, and is adhered to the upper surface of the transparent sheet member 11. Here, a diffusion plate may be used instead of the diffusion sheet 17. The thickness of the diffusion sheet 17 or the diffusion plate is determined according to the specification of the diffusion degree of the planar light emitting unit. Further, in the illustrated example, the diffusion sheet 17 is provided independently, but if the transparent sheet member 11 is mixed with a diffusion agent so as to have a function as a diffusion sheet, the diffusion sheet 17 can be omitted. You can also

The reflection plate 10 is for reflecting the light leaking downward out of the light diffused from the bare chip LED 7 to the upper surface light emitting surface, and is adhered to the lower surface of the transparent sheet member 12. As the reflection plate 10, an aluminum foil, an aluminum plate, a stainless plate, or the like can be used. Also, instead of providing the reflection plate 10, the same effect can be obtained even if the lower surface of the transparent sheet member 12 (the side opposite to the surface on which the transparent electrode 3 is formed) is painted white.

Next, an assembly process of the LED type planar light emitting unit of the embodiment will be described with reference to FIG. First, as shown in FIG. 2A, the transparent electrodes 21 and 22 are formed on one surface of the transparent sheet members 11 and 12, respectively. Next, as shown in FIG. 2B, conductive adhesive sheets 13 and 14 are attached on the surfaces of the transparent electrodes 21 and 22, respectively. Next, as shown in FIG. 2C, either one of the conductive adhesive sheets 13 and 14 is placed at a predetermined position of the conductive adhesive sheet 14, for example, the anode electrode 23 and the cathode electrode of the bare chip LED 15. A plurality of bare chip LEDs 15 are mounted so that any one of 24, for example, the cathode side electrode 24 is in contact. Next, as shown in FIG. 2D, a diffusion plate 16 is attached on the conductive adhesive sheet 14. Then, as shown in FIG. 2E, the transparent electrode 21 is formed and the conductive adhesive sheet 13 is attached. The transparent sheet member 11 is attached to electrically connect the anode electrode 23 and the transparent electrode 21 of the bare chip LED 15 to each other. And mechanically connect.

Further, as shown in FIG. 2F, final joining is performed by a thermocompression bonding method. That is, the members are pressed and adhered by the presses P1 and P2 with predetermined heat and pressure. As a result, the anode side electrode 23 and the cathode side electrode 24 of the bare chip LED 15 and the transparent electrodes 21 and 22 are electrically connected, respectively, and the mechanical attachment strength is increased.

Finally, as shown in FIG. 2 (g), the diffusion sheet 17 is attached to the upper surface of the transparent sheet member 11 by using an adhesive, and the reflection plate 18 is attached to the lower surface of the transparent sheet member 12. Stick with the agent. In these cases, when the diffusion function is added to the transparent sheet member 11, the diffusion sheet 17 can be omitted. Further, when a white coating is provided on the lower surface of the transparent sheet member 12, the reflector 18 can be omitted.

The planar light emitting unit thus obtained is connected to a drive circuit as shown in FIG. This drive circuit includes a DC power supply 31 and a current limiting resistor 32. Here, the transparent sheet members 11 and 12 and the transparent electrodes 21 and 22 project to the right side of the other members as shown in the figure, so that they can be easily connected to the drive circuit. In this way, the positive electrode of the DC power supply 31 is connected to the anode electrode 23 of the bare chip LED 15 via the transparent electrode 21 and the current limiting resistor 32. The negative electrode of the direct current power supply 31 is connected to the cathode electrode 24 of the bare chip LED 15 via the transparent electrode 22. This allows the planar light emitting unit to emit light.

[0019]

[Effect of device]

 According to the present invention, a plurality of bare chip LEDs are sandwiched by a transparent sheet member having a transparent electrode formed by using a conductive adhesive sheet, so that the manufacturing process can be simplified. In addition, since no solder or wire bonding is used, thinning can be achieved.

[Brief description of drawings]

FIG. 1 is a sectional view of a planar light emitting unit according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining a manufacturing process of the planar light emitting unit of FIG.

FIG. 3 is an explanatory diagram showing electrical connections of the planar light emitting unit of FIG.

FIG. 4 is a cross-sectional view of a conventional planar light emitting unit configured using discrete LEDs.

FIG. 5 is a cross-sectional view of a conventional planar light emitting unit configured using paired chip LEDs.

[Explanation of symbols]

 11, 12 Transparent sheet member 13, 14 Conductive adhesive sheet 15 Bare chip LED 16 Diffusing plate 17 Diffusing sheet 18 Reflecting plate 21, 22 Transparent electrode 23 Anode side electrode 24 Cathode side electrode 31 DC power supply 32 Current limiting resistance 41 LED substrate 42 Discrete LED 43 Reflector 44 Light guide 45 Diffusion sheet 51 LED substrate 52 Electrode copper foil 53 Silver paste 54 Bare chip LED 55 Copper foil 56 Wire 57 Light guide 58 Reflector 59 Diffusion sheet

Claims (4)

[Scope of utility model registration request] 1. A pair of transparent sheet members each having a transparent electrode formed on one surface thereof, a pair of conductive adhesive sheets, and a plurality of bare chip LEDs each having electrodes formed on an upper surface and a lower surface thereof. The plurality of bare chip LEDs with the pair of transparent sheet members via a conductive adhesive sheet
By sandwiching, to electrically connect the transparent electrode formed on one of the pair of transparent sheet members and the electrodes formed on the upper surface of the bare chip LEDs, the pair of transparent sheet members A planar light emitting unit, characterized in that the transparent electrode formed on the other side and the electrodes formed on the lower surfaces of the bare chip LEDs are electrically connected. 2. Light guide means for uniformly transmitting light emitted from the side surfaces of the plurality of bare chip LEDs in a planar manner is sandwiched between the pair of transparent sheet members via the pair of conductive adhesive sheets. The planar light emitting unit according to claim 1, wherein 3. A surface according to claim 1, wherein a diffusion means for diffusing light emitted from the upper surface of the bare chip LED is provided on one surface of the pair of transparent sheet members. Light emitting unit. 4. The planar light emitting unit according to claim 1, wherein a reflecting means for reflecting the light emitted from the bare chip LED is provided on the other surface of the transparent sheet member.