WO2007032815A1

WO2007032815A1 - Light-emitting device with light-exciting and light-mixing mechanisms

Info

Publication number: WO2007032815A1
Application number: PCT/US2006/027188
Authority: WO
Inventors: Shen-Nan Tong
Original assignee: Intex Recreation Corp
Current assignee: Intex Recreation Corp
Priority date: 2005-09-09
Filing date: 2006-07-13
Publication date: 2007-03-22
Anticipated expiration: 2008-03-09

Abstract

A light emitting device with light-exciting and light-mixing mechanism is formed to emit light through mixing a primary color of light produced by a light emitting diode chip and a complementary color of light emitted by phosphor-coating, excited by the primary color of light emitted by the device chip. By coating with the phosphor on the top and bottom surfaces and on the side surfaces of the light-emitting diode chip and on the surfaces of the packaging reflector, the heat and light absorption is reduced.

Description

Light-Emitting Device with Light-Exciting and Light-Mixing Mechanisms

Field of the Invention

The present invention relates to a light-emitting device with light-exciting and mixing mechanisms, in particular, a light-emitting device with phosphor-coating on the surrounding faces of its device chip to achieve more effective light-exciting and mixing.

Technical Background

Light-emitting devices have been widespread and used in every aspect of life. By emitting light of a desirable color, they have been used as indicators and many other applications. Owing to their low power consumption and being environment-friendly, light-emitting devices are gaining increasing importance as alternatives for conventional light bulbs and fluorescent light.

There are two techniques currently available for fabricating white light-emitting devices. One is to add phosphor into the encapsulating epoxy used in packaging light- emitting device chips. Through the exciting of the phosphor to emit yellow light by the blue light from the device chip, white light can be produced by combining excited yellow light with blue light from the device chip. Another technique involves exciting phosphor in the epoxy to emit red, blue and green lights simultaneously by an ultraviolet (UV) device chip. Lights of these three colors are then combined to form white light.

The conventional method of applying the phosphor-containing epoxy onto the device chip suffers from non-uniform light output which severely affects the quality of the white light.

Summary of the Invention

It is, therefore, an object of the present invention to provide a light-emitting device module with excellent light-exciting and light-mixing mechanisms.

The fabrication technique involves the homogeneous mixing of the phosphor powders and epoxy. The mixture is then coated on all six faces of the device chip and on the reflecting cup, which accommodates the device chip. Finally, the module is encapsulated with epoxy to complete the packaging. In addition to achieving homogeneous coating of phosphor over the device chip, the present invention also improves the exciting effect of light on phosphor and maximizes the mixing effect of lights having different colors.

According to the present invention, the phosphor-containing epoxy can be coated on the top and bottom faces and on the other four sides of the device chip. The phosphor is excited by the blue light of the device chip to emit light of a specific color which can be combined with the blue light emitted from the device chip to produce light of a desired color.

The light-emitting device chip can be made of a vertical cavity surface emitting laser (VECSEL) chip, UV light-emitting diode chip and other light-emitting diodes, emitting light of different colors.

The advantages of the present invention can be realized in terms of the exciting effect of light on the phosphor and the mixing of lights emitted from the phosphor and from the device chip. The homogeneous mixing of epoxy and phosphor powders and the subsequent homogeneous coating of such mixtures on all faces of a light-emitting device chip, pursuant to the present invention, greatly improves the exciting effect of light on the phosphor and maximizes the mixing effect of lights having different colors.

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 and Fig 2 illustrate examples of a first embodiment employing the principles of the present invention.

Fig 3 and Fig 4 illustrate examples of a second embodiment employing the principles of the present invention.

Fig 5 illustrates a third embodiment employing the principles of the present invention.

In the abovementioned Fig 1 through Fig 5, 1 refers to a substrate, 2 refers to epi- layers, 3 refers to the phosphor-coating (mixed with epoxy or silicone), 4 refers to the p-electrode of the device chip, 5 refers to the n-electrode of the device chip, 6 refers to the reflecting layer, 7 refers to blue light emitted by the light-emitting device chip, 8 refers to yellow light emitted by the phosphor. Description of the Preferred Embodiment

The fabrication of the first embodiment employing the principles of the present invention involves the coating of the mixture of epoxy and phosphor on the top face of a light-emitting device chip. As illustrated in Fig 1, the device comprises a substrate 1, epilayers 2, phosphor (silicone or epoxy mixture), coating 3, p-electrode 4, n-electrode 5. The epilayers 2 are deposited on substrate 1, p- and n-electrodes 4 and 5 are then formed on the device chip after the epilayers 2 have been formed or created onto the light-emitting device chip. The phosphor, containing epoxy, is evenly coated on the area not occupied by the electrodes. As a result, the exciting effect of the light from the device chip on the phosphor is enhanced, thereby improving the mixing effect of the lights emitted from phosphor and the device chip separately.

Examples of the first embodiment are shown in Fig 1 and Fig 2, which illustrate separately a standard packaged (Fig 1) and a flip-chip packaged (Fig 2) light-emitting device.

The fabrication of the second embodiment employing the principles of the present invention involves the coating of the mixture of epoxy and phosphor on the top and bottom faces of the device chip. Examples of the second embodiment are shown in Fig 3 and Fig 4, which illustrate a standard packaged light-emitting device (Fig 3) and a flip-chip packaged device (Fig. 4).

In Fig 3, underneath the phosphor coating 3 on the bottom face of the device chip, a metal reflector 6 is incorporated to reflect upward both the emitted light from the phosphor and the exciting light from the device chip, to produce a more profound mixing effect. A flip-chip packaged device chip utilizing the concept of the present invention is shown in Fig. 4. The p-and n-electrodes on the device chip can also function as light reflectors.

The fabrication of the third embodiment employing the principles of the present invention involves the coating of the mixture of epoxy and phosphor on all six faces of the device chip. An example of the third embodiment is shown in Fig 5. White light is produced by exciting the phosphor 3, emitting yellow light 8, with the blue light 7 emitted from the light-emitting device chip. Due to the enlarged area of the phosphor- coating being excited by the blue light, the mixing effect of the yellow and blue lights is significantly enhanced.

Having thus described the invention, I Claim:

Claims

1. A light-emitting device comprising, a light-emitting diode chip, a phosphor coating, wherein said phosphor coating is uniformly formed on the top and bottom surfaces of the light-emitting diode chip.

2. A light-emitting device comprising, a light-emitting diode chip having a reflector, a phosphor coating, wherein said phosphor-coating is uniformly formed on the bottom surface of the light-emitting diode chip and on the reflector.

3. A light-emitting device comprising, a light-emitting diode chip, a phosphor coating, wherein said phosphor coating is uniformly formed on the top and side surfaces or bottom and side surfaces of the light-emitting diode chip.

4. A light-emitting device comprising, a light-emitting diode chip, a phosphor coating, wherein said phosphor coating is formed on the bottom surface of the light-emitting diode chip.

5. The light-emitting device comprising, a light-emitting device chip having a reflector, a phosphor coating, formed on the top surface, the bottom surface, the side surfaces of the light-emitting diode chip and on the reflector.

6. The light-emitting device of claims 1, 2, 3, 4 or 5, wherein said phosphor coating is mixed with epoxy or silicone.

7. The light-emitting device of claims 1, 2, 3, 4 or 5, wherein said phosphor coating can be of varied compositions with varied coating locations to achieve special light-mixing effect

8. The light-emitting device according to claims 1 , 2, 3, 4 or 5, wherein said light-emitting diode chip is a member selected from the group consisting of, a vertical surface emitting laser diode chip, an ultraviolet light- emitting diode chip or a color light-emitting diode chip.