CN1783521A - white light emitting diode - Google Patents

Abstract

A white light LED includes a carrier, and a light emitting unit, a second LED chip and a phosphor disposed on the carrier. The light emitting unit is formed by connecting a first light emitting diode chip and a resistance element in series, and the first light emitting diode chip is suitable for emitting first color light. In addition, the second light emitting diode chip is suitable for emitting second color light and is connected with the light emitting unit in parallel. In addition, the fluorescent powder is arranged above the second light-emitting diode chip and is suitable for being excited by the second color light to generate a third color light. The white light LED has lower manufacturing cost and can provide better color saturation and display color temperature.

Description

white light emitting diode

technical field

The present invention relates to a light-emitting diode, and in particular to a three-wavelength white light-emitting diode.

Background technique

Light-emitting diodes use III-V elements as the main material of the light-emitting layer, and apply current to the light-emitting layer to release excess energy in the form of light through the combination of electrons and holes, thereby achieving the purpose of light emission. Different from traditional lighting methods such as heating or discharging, because the light emitting phenomenon of light emitting diodes is cold light emission, it has a long service life and no warm-up time (idling time) is required. In addition, light-emitting diodes also have the advantages of fast response speed, small size, low power consumption, low pollution (mercury-free), high reliability, and suitable for mass production, so they can be used in a wide range of fields. In recent years, due to the continuous improvement of the luminous efficiency of light-emitting diodes, white light-emitting diodes have gradually replaced traditional fluorescent lamps and incandescent bulbs in application fields such as scanner light sources, liquid crystal screen backlights, or lighting equipment.

Commonly known white light emitting diodes mainly include the following types:

1. Use red light, blue light and green light-emitting diode chips at the same time to generate white light. Wherein, the driving voltage of each light-emitting diode chip can be adjusted through an external driving chip, so as to mix the monochromatic light emitted by the above-mentioned light-emitting diode chip to generate three-wavelength white light. However, since this white light emitting diode needs to use a plurality of single-color light-emitting diode chips at the same time, and different single-color light-emitting diode chips, such as red light-emitting diode chips and blue light-emitting diode chips, have different driving voltages, so An external driver chip is required to adjust the driving voltage, resulting in higher manufacturing costs and more complicated driving circuits.

2. Use blue light-emitting diode chips with yellow phosphor to generate white light. Among them, the yellow inorganic phosphor can emit yellow fluorescence after being irradiated by the blue light emitted by the blue light-emitting diode chip, and when the yellow fluorescence is mixed with the original blue light, two-wavelength white light can be obtained. However, due to the low luminous efficiency of this kind of white light emitting diode, and it is a two-wavelength white light emitting diode (only blue light and yellow light are mixed), it is not as good as the other three wavelengths in terms of color saturation and display color temperature. type of white light-emitting diode.

Contents of the invention

In view of this, the object of the present invention is to provide a white light emitting diode with lower manufacturing cost and simpler driving circuit.

Another object of the present invention is to provide a white light emitting diode with better color saturation and display color temperature.

Based on the above or other objectives, the present invention proposes a white light emitting diode, including a carrier, a light emitting unit and a second light emitting diode chip disposed on the carrier. Wherein, the light-emitting unit is composed of a first light-emitting diode chip and a resistance element connected in series, and the first light-emitting diode chip is suitable for emitting a first color light. In addition, the second light emitting diode chip is suitable for emitting light of the second color, and the second light emitting diode chip is connected in parallel with the light emitting unit.

In a preferred embodiment of the present invention, the above-mentioned white light emitting diode, for example, further includes phosphor powder disposed above the second light emitting diode chip, and the phosphor powder is suitable for being excited by the second color light to generate the third color light.

The present invention also provides a white light emitting diode, including a carrier, a light emitting unit, a second light emitting diode chip and a third light emitting diode chip. The light-emitting unit is arranged on the carrier, and the light-emitting unit is composed of a first light-emitting diode chip and a resistance element connected in series, wherein the first light-emitting diode chip is suitable for emitting a first color light. In addition, the second light emitting diode chip and the third light emitting diode chip are arranged on the carrier, wherein the second light emitting diode chip is suitable for emitting light of the second color, and the third light emitting diode chip is suitable for emitting light of the third color, and the light emitting unit, the first light emitting diode chip The two LED chips and the third LED chip are connected in parallel.

Based on the above description, the white light emitting diode of the present invention adjusts the driving voltage between different light emitting diode chips through the built-in resistance element, so as to achieve the purpose of using the same power supply to drive the light emitting diode chips connected in parallel, so there is no need to use an external In the case of a driving chip, the white light emitting diode of the present invention can have lower manufacturing cost and simpler driving circuit. In addition, the present invention can also produce three-wavelength white light through the combination of two light-emitting diode chips and phosphor powder. Compared with the known two-wavelength white light-emitting diode, the three-wavelength white light-emitting diode of the present invention can provide better The color saturation and display color temperature.

In order to make the above and other objects, features and advantages of the present invention more comprehensible, preferred embodiments are specifically cited below and described in detail with accompanying drawings.

Description of drawings

FIG. 1A is a schematic cross-sectional view of a white light emitting diode according to a preferred embodiment of the present invention.

FIG. 1B is a circuit diagram of the white light emitting diode in FIG. 1A .

FIG. 2 is a circuit diagram of another white light emitting diode according to a preferred embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view of a white light emitting diode according to another embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view of another white light emitting diode according to other embodiments of the present invention.

Description of main component marking

100, 200: white light emitting diode

102, 402: carrier

102a, 402a: pockets

104, 204: power supply

110, 210, 310, 410: red light emitting diode chips

110a, 220a: light emitting unit

112, 212: resistance element

114, 314, 414: red light

120, 220, 320, 420: blue LED chips

124, 324, 424: Blu-ray

134, 334, 434: yellow light

140, 340, 440: Phosphor powder

150, 450: encapsulation colloid

230: Green LED

452: Transparent cover

452a: Bottom

Detailed ways

Please refer to FIGS. 1A and 1B at the same time, wherein FIG. 1A is a schematic cross-sectional view of a white light emitting diode according to a preferred embodiment of the present invention, and FIG. 1B is a circuit diagram of the white light emitting diode of FIG. 1A . In addition, in order to simplify the drawings and clearly express the features of the present invention, the schematic cross-sectional view of FIG. 1A does not show the relevant connecting wires or circuits of the substrate. As shown in Figures 1A and 1B, the white light emitting diode 100 includes a red light emitting diode chip 110, a blue light emitting diode chip 120 and a carrier 102, wherein the carrier 102 is, for example, a package substrate, and the red light emitting diode chip 110 and the blue light emitting diode chip 110 The chip 120 is, for example, disposed in the cavity 102 a on the surface of the carrier 102 . In addition, the red light emitting diode chip 110 is connected in series with the resistance element 112 to form a light emitting unit 110a, and the blue light emitting diode chip 120 is connected in parallel with the light emitting unit 110a and coupled to the carrier 102 to be connected to the power supply 104 through the carrier 102.

Please refer to FIG. 2 , which is a circuit diagram of another white light emitting diode according to a preferred embodiment of the present invention. The white light emitting diode 200 has, for example, a red light emitting diode chip 210, a blue light emitting diode chip 220 and a green light emitting diode chip 230 to output three-wavelength white light after light mixing, wherein the red light emitting diode chip 210 is connected in series with a resistor element 212 to form The light emitting unit 220 a , and the blue light emitting diode chip 220 and the green light emitting diode chip 230 are respectively connected in parallel with the light emitting unit 220 a to be coupled to the power source 204 .

In the above-mentioned embodiments of the present invention, since the driving voltage required by the red light emitting diode chip is low, and the driving voltage required by the blue light emitting diode chip and the green light emitting diode chip is relatively high, when the light emitting unit, the blue light emitting diode chip When the chip and the green light emitting diode chip are coupled to the same voltage source, the driving voltage obtained by the red light emitting diode chip can be adjusted through the resistance element, so that the red light emitting diode chip can operate normally. In this way, there is no need to separately add a driver chip to each light-emitting diode chip, so as to save the required manufacturing cost and simplify the driving circuit.

It is worth mentioning that the above-mentioned resistance element is, for example, a metal thin film or a ceramic thin film formed on the surface of the carrier or its inner circuit. Of course, in other embodiments of the present invention, the resistance element can also be an independent resistor, which can be coupled to the carrier. In addition, although the carrier shown in the above embodiments is in the form of a packaging substrate, in other embodiments of the present invention, it can also be a packaging bracket, for carrying the above-mentioned light-emitting diode chips and resistor elements, but it is related The wiring and setting methods are similar to those of the above-mentioned embodiments, so the details will not be repeated here.

Please refer to FIG. 1A again. In the present invention, an encapsulant 150 may be provided above the blue light emitting diode chip 120, and its material is, for example, epoxy resin. chip 120 and optionally covers the resistive element 112 . In addition, the encapsulant 150 is doped with phosphor powder 140, for example, its material is Y ₃ Al ₁₅ O ₁₂ : Ce ³⁺ and Y ₃ Al ₁₅ O ₁₂ : Tb ³⁺ , wherein the phosphor powder 140 is suitable for being used by blue light emitting diodes. The blue light 124 emitted by the chip 120 is excited to generate colored light with a wavelength between 520 nm and 620 nm, such as yellow light 134 . In this way, the three-wavelength white light can be generated through the blue light 124 , the yellow light 134 and the red light 114 emitted by the red LED chip 110 .

In addition to the above-mentioned embodiments, the present invention also provides various other arrangements of phosphors. Please refer to FIG. 3 , which is a schematic cross-sectional view of a white light emitting diode according to other embodiments of the present invention, wherein the phosphor powder 340 is directly coated on the surface of the blue light emitting diode chip 320 , which can also be covered by the blue light emitting diode chip 320 The emitted blue light 324 is excited to emit a third color light, such as yellow light 334 , so the blue light 324 , yellow light 334 and red light 314 emitted by the red LED chip 310 can be mixed to obtain three-wavelength white light.

In addition, please refer to FIG. 4 , which is a schematic cross-sectional view of another white light emitting diode according to other embodiments of the present invention. Wherein, the red light emitting diode chip 410 and the blue light emitting diode chip 420 are disposed in the cavity 402a of the carrier 402, and a transparent cover 452, such as glass, is disposed above the cavity 402a. In addition, the fluorescent powder 440 is coated on the bottom 452a of the transparent cover 452, and the space enclosed by the transparent cover 452 and the cavity 402a is filled with encapsulant 450 to cover the above-mentioned red light emitting diode chip 410 and the blue light emitting diode chip 410. Diode chip 420 . The three-wavelength white light can be obtained through the blue light 424 emitted by the blue LED chip 420 , the red light 414 emitted by the red LED chip 410 , and the yellow light 434 emitted by the excited phosphor 440 .

To sum up, in the white light emitting diode of the present invention, a light emitting diode chip (such as a red light emitting diode chip) with a lower driving voltage is connected in series with a resistance element, wherein the resistance element can be set on a carrier, for example, to adjust the light emitting diode. The driving voltage obtained by the chip. In addition, the present invention can also use the first light-emitting diode chip and the second light-emitting diode chip as excitation light sources, and add fluorescent powder to generate a third color light with a wavelength between 520nm and 620nm after being excited, so that the first The colored light emitted by the LED chip and the second LED chip can be mixed with the third colored light to form three-wavelength white light.

Therefore, the white light emitting diode of the present invention can achieve the purpose of integrating the driving voltages of different light emitting diode chips without using an external driving chip, so it can have lower manufacturing cost and simplify the driving circuit. In addition, the white light emitting diode of the present invention can not only use three light emitting diode chips as the light source, but also use two light emitting diode chips and a combination of phosphor powder to provide three-wavelength white light, which is different from the known two-wavelength white light. Compared with light-emitting diodes, it not only has higher luminous efficiency, but also has better color saturation and display color temperature.

Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any ordinary person in the technical field to which the invention belongs can make some changes and changes without departing from the spirit and scope of the present invention. Improvement, so the scope of protection of the present invention should be defined by the claims.

Claims (23)

1. A white light emitting diode, characterized in that it comprises: carrier; A light-emitting unit is arranged on the carrier, wherein the light-emitting unit is composed of a first light-emitting diode chip and a resistance element connected in series, and the first light-emitting diode chip is suitable for emitting light of a first color; and The second light emitting diode chip is arranged on the carrier, wherein the second light emitting diode chip is suitable for emitting a second color light, and the second light emitting diode chip is connected in parallel with the light emitting unit. 2. The white light emitting diode according to claim 1, wherein the first light emitting diode chip comprises a red light emitting diode chip. 3. The white light emitting diode according to claim 1, wherein the second light emitting diode chip comprises a blue light emitting diode chip. 4. The white light emitting diode according to claim 1, further comprising a phosphor disposed above the second light emitting diode chip, and the phosphor is suitable for being excited by the second color light to generate a third color light. 5. The white light emitting diode according to claim 4, wherein the wavelength of the third color light is between 520nm and 620nm. 6 . The white light emitting diode according to claim 4 , wherein the material of the phosphor comprises one of Y ₃ Al ₁₅ O ₁₂ : ^{Ce 3+} and Y ₃ Al ₁₅ O ₁₂ : Tb ³⁺ . 7. The white light emitting diode according to claim 4, wherein the phosphor is coated on the surface of the second light emitting diode chip. 8. The white light emitting diode according to claim 4, further comprising an encapsulant disposed on the carrier, and the encapsulant at least covers the first LED chip and the second LED chip, and the encapsulant Phosphor powder is doped in the encapsulation colloid. 9. The white light emitting diode according to claim 8, wherein the encapsulant is made of epoxy resin. 10. The white light emitting diode according to claim 4, further comprising a transparent cover disposed on the carrier, and the transparent cover covers between the first light emitting diode chip and the second light emitting diode chip above, and the fluorescent powder is coated on the bottom of the transparent cover. 11. The white light emitting diode according to claim 10, wherein the transparent cover is made of glass. 12. The white light emitting diode according to claim 1, wherein the resistor element comprises one of a metal thin film and a ceramic thin film. 13. The white light emitting diode according to claim 1, wherein the carrier comprises one of a package holder and a package substrate. 14. A white light emitting diode, characterized in that it comprises: carrier; A light-emitting unit is arranged on the carrier, wherein the light-emitting unit is composed of a first light-emitting diode chip and a resistance element connected in series, and the first light-emitting diode chip is suitable for emitting a first color light; a second light emitting diode chip disposed on the carrier, wherein the second light emitting diode chip is suitable for emitting light of a second color; and The third LED chip is arranged on the carrier, wherein the third LED chip is suitable for emitting light of a third color, and the light emitting unit, the second LED chip and the third LED chip are connected in parallel. 15. The white light emitting diode according to claim 14, wherein the first light emitting diode chip comprises a red light emitting diode chip. 16. The white light emitting diode according to claim 14, wherein the second light emitting diode chip comprises a blue light emitting diode chip. 17. The white light emitting diode according to claim 14, wherein the third light emitting diode chip comprises a green light emitting diode chip. 18. The white light emitting diode according to claim 14, further comprising an encapsulant disposed on the carrier, and the encapsulant at least covers the first LED chip, the second LED chip and the second LED chip. Three LED chips. 19. The white light emitting diode according to claim 18, wherein the encapsulant is made of epoxy resin. 20. The white light emitting diode according to claim 14, further comprising a transparent cover disposed on the carrier, and the transparent cover covers the first light emitting diode chip, the second light emitting diode chip and above the third LED chip. 21. The white light emitting diode according to claim 20, wherein the transparent cover is made of glass. 22. The white light emitting diode according to claim 14, wherein the resistance element comprises one of a metal thin film and a ceramic thin film. 23. The white light emitting diode according to claim 14, wherein the carrier comprises one of a package holder and a package substrate.

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