WO2007015732A2

WO2007015732A2 - A method of varying the color of light emitted by a light-emitting device

Info

Publication number: WO2007015732A2
Application number: PCT/US2006/025968
Authority: WO
Inventors: Shen-Nan Tong; Hsin-Wang Chiu
Original assignee: Intex Recreation Corp.
Priority date: 2005-08-01
Filing date: 2006-06-30
Publication date: 2007-02-08
Also published as: WO2007015732A3

Abstract

A method of varying the color of light emitted by a light-emitting device comprising a light-emitting device chip in a phosphor-coated or a phosphor- embedded enclosure. By coating or embedding phosphor on or in the enclosure of the light-emitting device, the phosphor is excited by the blue light emitted from the light-emitting device chip to emit yellow light. Through mixing both the blue and yellow lights, white light is produced.

Description

A Method of Varying the Color of Light Emitted by a Light-Emitting Device

Field of the Invention

The present invention relates to a method of varying the color of light

emitted by a light-emitting device, more particularly, to a method of varying

the color of light of a light-emitting device by incorporating a phosphor-

containing enclosure into a light-emitting device module.

Technical Background

White light consists of several individual lights of different color. White

light visible to a normal human's eye constitutes either two primary colors

(i.e. blue and yellow) or three primary colors (i.e. blue, green and red

(RGB)). White light-emitting device modules available in the market today

are normally fabricated, either by incorporating yellow, Yttrium Aluminum

Garnet (YAG) phosphor into a blue light-emitting device module or RGB

phosphor into an ultraviolet (UV) light-emitting device module. The latter,

in particular, holds greater promise to the solid-state lighting of the future.

A great deal of attention has been focused on the potential applications

for white light-emitting devices in general lighting and in LCD (Liquid

Crystal Display) backlighting, as the technology of solid-state light

advances. The conventional technique of fabricating a white light-emitting device compnses either utilizing the direct coating of phosphor (YAG or

Terbium Aluminum Garnet (TAG) phosphor) on a blue device chip or RGB

phosphor on a UV device chip. Since the manufacturing process is

complicated, the cost of making these modules is expensive.

Summary of the Invention

It is therefore the purpose of the present invention to provide a method

of varying the color of light emitted by a light-emitting device module, more

particularly, to provide a method of producing white light by a blue light-

emitting device chip. The present invention consists of a light-emitting

device chip and an enclosure, such as a cover, hood or lens, coated or

embedded with a phosphor. The advantage of the present invention is that

the enclosure coated or embedded with phosphor can be easily incorporated

in the blue light-emitting device module. The phosphor can then be directly

excited by the blue light emitting from the light-emitting device chip to emit

light of yellow color. By mixing blue light with its complementary yellow

light, white light, useful for applications, can be produced.

Another advantage of the present invention is that an enclosure coated

or embedded with YAG phosphor can also be affixed easily upon the

encapsulated device chip. Thus, white light can be generated through the

producing and mixing of both the blue and yellow light. The light-emitting device chip employed in the present invention is not

limited to a chip emitting light of blue color. A light-emitting device chip

emitting light of a different color, as well as ultraviolet, can also be utilized

in the present invention.

The quantity of light-emitting device chips used in the present invention

can either be single chip or a plurality of chips. The geometry of a plurality

of device chips can be in the form of any configuration, such as square,

rectangular or hexagonal. The placement of the device chip can be on the

bottom or in the center of the device module. It is also possible to place the

device chip either inside or outside the device module.

According to the principles of the present invention, YAG yellow

phosphor or RGB phosphor, or phosphor emitting light of a different color,

can be employed to produce a light of desired color, while being excited by

the light emitting from the light-emitting device chip.

According to the principles of the present invention, the

abovementioned enclosure can be made of glass, plastic or other transparent

or semi-transparent materials. The configuration of the enclosure can be in

the form of a half-circle, plane, circle, column or other forms. To achieve a

desired purpose or application, an enclosure containing a phosphor can be

fabricated utilizing techniques of coating, embedding, spraying or injection

molding. The enclosure can be affixed to the device module with epoxy, glue, resm adhesive, a binder or other bonding medium.

One advantage of the present invention is realized in terms of its

manufacturing cost. In contrast to conventional white light-emitting device

modules employing a high-cost white light-emitting diode chip, the present

invention utilizes low-cost blue or UV light-emitting diode chips together

with low-cost, phosphor-containing enclosures. This presents a great cost

advantage over conventional device modules.

Brief Description of the Drawings

These and other features and advantages of the present invention will be

better understood by reference to the following detailed description when

considered in connection with the accompanying drawings, wherein:

FIG 1, illustrates an example of a first embodiment employing the

principles of the present invention.

FIG 2, illustrates another example of the first embodiment employing

the principles of the present invention.

FIGs 3, 4, 5 and 6, illustrate other examples of the first embodiment in

various different applications employing the principles of the present

invention.

FIGs 7, 8 and 9, illustrate examples of the second embodiment

employing the principles of the present invention. .KKis IU and H₅ illustrate examples of the second embodiment having

various different placements of the device chips, employing the principles of

the present invention.

90 In the abovementioned FIG 1 to FIG 10, 1 refers to a light-emitting

device module, 2 refers to a light-emitting device chip, 3 refers to a

phosphor-coated enclosure, 4 refers to a phosphor-embedded enclosure, 5

refers to multiple numbers of light-emitting device chips connected in

series, 6 refers to glass plate, 7 refers to phosphor, 8 refers to a lead frame

95 for packaging a light-emitting device chip, 9 refers to encapsulating epoxy,

10 refers to a light-emitting device chip and 11 refers to adhesive medium.

Description of the Preferred Embodiment

The first embodiment employing the principles of the present invention

00 is shown separately in FIGs 1 and 2. The device module 1 consists of a

light-emitting device chip 2, an enclosure coated with YAG phosphor 3 and

an enclosure embedded with YAG phosphor 4. Being excited by blue light

emitting from device chip 2, the YAG phosphor 3 or 4, on or in the

enclosure, emits a complementary yellow light, which is then mixed with

05 the exciting blue light through the lens, to produce a white light.

An example of the first embodiment in application is illustrated in

FIG 3, a spherical light-emitting device module 1 having a light-emitting device chip 2 placed on the bottom, with an enclosure 3. FIG 4 depicts a

cylindrical light-emitting device module 1 having the light-emitting

110 device chips 2 placed on two ends of the module with an enclosure 3.

FIG 5 depicts a cylindrical light-emitting device module 1 having an

enclosure 3 and a plurality of light-emitting device chips 5 connected in

series. FIG 6 depicts a glass plate 6 coated with YAG phosphor 7, placed

above a light-emitting device chip 2, to produce outward white light,

115 while being excited by the blue light emitting from underneath light-

emitting device chip 2.

The second embodiment, employing the principles of the present

invention, is illustrated separately in FIG 7, FIG 8 and FIG 9. The

modules consist of a lead frame 8, encapsulating epoxy 9, light-emitting

120 device chip 10, an enclosure 3 coated with YAG phosphor, or enclosure 4

embedded with YAG phosphor. The fabrication of the modules includes

bonding light-emitting device chips 10 onto lead frame 8 and then

encapsulating device chips 10 with epoxy 9, and finally placing a

phosphor-coated enclosure 3 or phosphor-embedded enclosure 4 onto the

125 epoxy with adhesive 11 to complete the process. White light is produced

by exciting the phosphor coating on the enclosure 3 or 4, by the blue light

emitting from underneath light-emitting device chip 10.

The module can either be fabricated using a single device chip 10, as shown in FIG 10, or a plurality of device chips 10 in an array, as shown in

FIG 11, as well as other arrangements. In both cases, the enclosures are

phosphor-coated enclosures 3.

Having thus described the invention, We Claim:

Claims

Claim 1 : A light-emitting device module, comprising a light-emitting device

135 chip and a phosphor containing enclosure covering the module.

Claim 2: The module of Claim 1 wherein said enclosure is a cover, hood or

lens.

140 Claim 3: The module of Claim 1, wherein said phosphor is a yellow

phosphor, a red, green, blue phosphor or other phosphors of different colors.

Claim 4: The module of Claim 1, wherein said enclosure is made of glass,

plastic or other transparent or semi-transparent materials.

145

Claim 5: The module of Claim 1 wherein said enclosure is in the form of a

half-circle, plane, cylinder, column or other configuration.

Claim 6: The module of Claim 1 wherein said enclosure is coated,

150 embedded, sprayed or injection-molded with phosphor.

Claim 7: The module of Claim 1, wherein said light-emitting device chip is

placed at the bottom of the enclosure. 155 Claim 8: The module of Claim 1 wherein said light-emitting device chip is

placed inside the enclosure.

Claim 9: The module of Claim 1 where said light-emitting device chip is

placed outside the enclosure.

160

Claim 10: The module of Claim 1 wherein said module comprises a single

chip or a plurality of light-emitting device chips.

Claim 11: The module of Claim 1 comprising a plurality of light-emitting

165 device chips in a linear, matrix, array or other form of arrangement.

Claim 12: The module of Claim 1, wherein the light-emitting device chip is

encapsulated in epoxy.

170 Claim 13: The module of Claim 1 wherein said enclosure is affixed upon the

light-emitting device chip with epoxy, glue, resin, adhesive or binder.

Claim 14: The module of Claim 1 wherein said light-emitting device chip is

a blue light-emitting device chip, ultraviolet light-emitting device chip or

175 other light-emitting device chip, emitting a different color of light.