RED PHOSPHOR, WHITE LIGHT EMITTING DIODE, AND BACKLIGHT MODULE

Abstract

A red phosphor comprising a first red phosphor and a second red phosphor having adjustable wavelength. The first red phosphor is made from a substance having structure formula M.sub.2AX.sub.6:Mn.sup.4+, wherein the element M is selected from Li, Na, K, Rb or Cs, the element A is selected from Ti, Si, Ge or Zr, and the element X is selected from F, Cl or Br; the ratio of the second red phosphor to the red phosphor ranges from 0.01% to 15%. Further provided is a white LED and a backlight module. The adjustably colored points of a device including M.sub.2AX.sub.6:Mn.sup.4+ are achieved by adding a second red phosphor having various wavelength to the red phosphor including M.sub.2AX.sub.6:Mn.sup.4+ whose emission wavelength and spectral shape cannot be adjusted. The device can enable full range of colored points with hardly any reduction of the NTSC color gamut.

Claims

1. A red phosphor comprising a first red phosphor and a second red phosphor having adjustable emission wavelength; the first red phosphor is made from a substance having structure formula M.sub.2AX.sub.6:Mn.sup.4+, wherein the element M is selected from Li, Na, K, Rb or Cs, the element A is selected from Ti, Si, Ge or Zr, and the element X is selected from F, Cl or Br; the ratio of the second red phosphor to the red phosphor ranges from 0.01% to 15%.

2. The red phosphor of claim 1, wherein the second red phosphor comprises one or more compound selected from CaAlSiN3:Eu, SrLiAl3N4:Eu or Quantum Dot.

3. The red phosphor of claim 1, wherein the second red phosphor has an emission wavelength ranging from 630 nm to 670 nm.

4. The red phosphor of claim 3, wherein the second red phosphor is selected from the followings: the second red phosphor having an emission wavelength of 630 nm, and a FWHM being no greater than 35 nm; or the second red phosphor having an emission wavelength that is larger than 630 nm and less than or equal to 635 nm, and a FWHM being no greater than 40 nm; or the second red phosphor having an emission wavelength that is larger than 635 nm and less than or equal to 640 nm, and a FWHM being no greater than 50 nm; or the second red phosphor having an emission wavelength that is larger than 640 nm and less than or equal to 645 nm, and a FWHM being no greater than 60 nm; or the second red phosphor having an emission wavelength that is larger than 645 nm and less than or equal to 650 nm, and a FWHM being no greater than 70 nm; or the second red phosphor having an emission wavelength that is larger than 650 nm and less than or equal to 655 nm, and a FWHM being no greater than 90 nm; or the second red phosphor having an emission wavelength that is larger than 655 nm and less than or equal to 660 nm, and a FWHM being no greater than 100 nm; or the second red phosphor having an emission wavelength that is larger than 660 nm and less than or equal to 665 nm, and a FWHM being no greater than 105 nm; or the second red phosphor having an emission wavelength that is larger than 665 nm and less than 670 nm, and a FWHM being no greater than 110 nm; or the second red phosphor having an emission wavelength of 670 nm, and a FWHM being no greater than 110 nm.

5. The red phosphor of claim 3, wherein, with the addition of the second red phosphor to the first red phosphor, an increasing light emission intensity from the red phosphor, compared with an light emission intensity from the first red phosphor before the second red phosphor added, at the emission wavelength ranging from 600 nm to 630 nm will be less than or equal to an increasing light emission intensity from the red phosphor, compared with an light emission intensity from the first red phosphor before the second red phosphor added, at the emission wavelength ranging from 630 nm to 670 nm.

6. The red phosphor of claim 3, wherein the second red phosphor has an emission wavelength ranging from 630 nm to 670 nm, and a FWHM ranging from 35 nm to 110 nm.

7. A white LED comprising the red phosphor of claim 1, wherein a red light, a blue light and a green light are mixed simultaneously to produce a white light; the red light is emitted by the red phosphor which absorbed the blue light or the green light.

8. The white LED of claim 7, wherein the second red phosphor comprises one or more compound selected from CaAlSiN3:Eu, SrLiAl3N4:Eu or Quantum Dot.

9. The white LED of claim 7, wherein the second red phosphor has an emission wavelength ranging from 630 nm to 670 nm.

10. The white LED of claim 9, wherein the second red phosphor is selected from the followings: the second red phosphor having an emission wavelength of 630 nm, and a FWHM being no greater than 35 nm; or the second red phosphor having an emission wavelength that is larger than 630 nm and less than or equal to 635 nm, and a FWHM being no greater than 40 nm; or the second red phosphor having an emission wavelength that is larger than 635 nm and less than or equal to 640 nm, and a FWHM being no greater than 50 nm; or the second red phosphor having an emission wavelength that is larger than 640 nm and less than or equal to 645 nm, and a FWHM being no greater than 60 nm; or the second red phosphor having an emission wavelength that is larger than 645 nm and less than or equal to 650 nm, and a FWHM being no greater than 70 nm; or the second red phosphor having an emission wavelength that is larger than 650 nm and less than or equal to 655 nm, and a FWHM being no greater than 90 nm; or the second red phosphor having an emission wavelength that is larger than 655 nm and less than or equal to 660 nm, and a FWHM being no greater than 100 nm; or the second red phosphor having an emission wavelength that is larger than 660 nm and less than or equal to 665 nm, and a FWHM being no greater than 105 nm; or the second red phosphor having an emission wavelength that is larger than 665 nm and less than 670 nm, and a FWHM being no greater than 110 nm; or the second red phosphor having an emission wavelength of 670 nm, and a FWHM being no greater than 110 nm.

11. The white LED of claim 9, wherein, with the addition of the second red phosphor to the first red phosphor, an increasing light emission intensity from the red phosphor, compared with an light emission intensity from the first red phosphor before the second red phosphor added, at the emission wavelength ranging from 600 nm to 630 nm will be less than or equal to an increasing light emission intensity from the red phosphor, compared with an light emission intensity from the first red phosphor before the second red phosphor added, at the emission wavelength ranging from 630 nm to 670 nm.

12. The white LED of claim 9, wherein the second red phosphor has an emission wavelength ranging from 630 nm to 670 nm, and a FWHM ranging from 35 nm to 110 nm.

13. The white LED of claim 7, further comprising a green phosphor having an emission wavelength ranging from 510 nm to 550 nm and a FWHM being no greater than 70 nm, and/or a blue LED chip for emitting blue light, wherein the green light is emitted by the green phosphor which absorbed the blue light.

14. The white LED of claim 13, further comprising a leadframe, a thermoplastic or thermosetting transparent protective layer, and a fluorescence conversion layer provided on the leadframe; the blue LED chip is arranged on the leadframe and is covered by the fluorescence conversion layer; the green phosphor and the red phosphor are dispersed in the fluorescence conversion layer which is wrapped up by the thermoplastic or thermosetting transparent protective layer wherein the blue light, the green light and the red light are distributed.

15. The backlight module comprising the white LED of claim 7.

16. The backlight module of claim 15, further comprising a green phosphor having an emission wavelength ranging from 510 nm to 550 nm and a FWHM being no greater than 70 nm, and/or a blue LED chip for emitting blue light, wherein the green light is emitted by the green phosphor which absorbed the blue light.

17. The backlight module claim 16, further comprising a leadframe, a thermoplastic or thermosetting transparent protective layer, and a fluorescence conversion layer provided on the leadframe; the blue LED chip is arranged on the leadframe and is covered by the fluorescence conversion layer; the green phosphor and the red phosphor are dispersed in the fluorescence conversion layer which is wrapped up by the thermoplastic or thermosetting transparent protective layer wherein the blue light, the green light and the red light are distributed.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0022] FIG. 1 is a typical spectrogram of M.sub.2AX.sub.6:Mn.sup.4+ and the red phosphor according to embodiments of present invention;

[0023] FIG. 2 is a structure schematic view of a white LED according to the embodiments of the present invention;

[0024] FIG. 3 is a schematic view of direct-lit module with high color gamut according to the embodiment 6 of the present invention;

[0025] FIG. 4 is a schematic view of edge-lit module with high color gamut according to the embodiment 7 of the present invention;

LIST OF REFERENCE CHARACTERS

[0026]

TABLE-US-00001 List of reference characters 100 White LED 101 Leadframe 102 Chip 103 Fluorescence Conversion Layer 200 LED direct-lit backlight module 201 Lens 202 PCB 203 Backing Plate 204 Lower Diffusion Sheet 205 Prism Sheet 206 Upper Diffusion Sheet 300 LED edge-lit backlight module 301 PCB 302 Reflective Sheet 303 Light Guide Plate 304 Brightness Enhancement Film 305 Diffuser Film

DETAILED DESCRIPTION OF THE INVENTION

[0027] The invention will be described in more details hereinafter with reference to the figures and embodiments.

[0028] The present invention provides a red phosphor comprising a first red phosphor and a second red phosphor having adjustable wavelength.

[0029] The first red phosphor is made from a substance having structure formula M.sub.2AX.sub.6:Mn.sup.4+, wherein

the element M is selected from Li, Na, K, Rb or Cs,
the element A is selected from Ti, Si, Ge or Zr, and
the element X is selected from F, Cl or Br.

[0030] The ratio of the second red phosphor to the red phosphor ranges from 0.01% to 15%. The second red phosphor comprises one or more compound selected from CaAlSiN.sub.3: Eu, SrLiAl.sub.3N.sub.4: Eu, or QD. The second red phosphor has an emission wavelength ranging from 630 nm to 670 nm and a FWHM ranging from 35 nm to 110 nm.

[0031] To improve the color purity of the red phosphor and the NTSC color gamut, the second red phosphor is added into the first red phosphor to form the red phosphor, whereby the increasing light emission intensity from the red phosphor, compared with the light emission intensity from the first red phosphor before the second red phosphor added, at the emission wavelength ranging from 600 nm to 630 nm will be less than or equal to the increasing light emission intensity from the red phosphor, compared with the light emission intensity from the first red phosphor before the second red phosphor added, at the emission wavelength ranging from 630 nm to 670 nm, as shown in FIG. 1. In practice, the first red phosphor constitutes the main part of the red phosphor, and the second red phosphor having the variable emission wavelength is added therein for the sake of adjusting the colored points (because the colored points are non-adjustable if there are only the first phosphor due to the invariant spectrum of the first phosphor no matter it comprises Si, Ge, or Ti), where the second red phosphor is selected to have a special emission wavelength and FWHM, such that the increasing light emission intensity from the red phosphor, compared with the light emission intensity from the first red phosphor before the second red phosphor added, at the emission wavelength ranging from 600 nm to 630 nm will be less than or equal to the increasing light emission intensity from the red phosphor, compared with the light emission intensity from the first red phosphor before the second red phosphor added, at the emission wavelength ranging from 630 nm to 670 nm. For example, when the second red phosphor is selected to have an emission wavelength of 630 nm and a FWHM of 30 nm, the foresaid increasing light emission intensity at the emission wavelength of 614 nm is equal to the increasing light emission intensity at the emission wavelength of 647 nm; when the second red phosphor is selected to have an emission wavelength of 650 nm and a FWHM of 70 nm, the foresaid increasing light emission intensity at the emission wavelength of 614 nm is less than the increasing light emission intensity at the emission wavelength of 647 nm.

[0032] Preferably, the second red phosphor is selected from the followings:

the second red phosphor having an emission wavelength of 630 nm, and a FWHM being no greater than 35 nm; or
the second red phosphor having an emission wavelength that is larger than 630 nm and less than or equal to 635 nm, and a FWHM being no greater than 40 nm; or
the second red phosphor having an emission wavelength that is larger than 635 nm and less than or equal to 640 nm, and a FWHM being no greater than 50 nm; or
the second red phosphor having an emission wavelength that is larger than 640 nm and less than or equal to 645 nm, and a FWHM being no greater than 60 nm; or
the second red phosphor having an emission wavelength that is larger than 645 nm and less than or equal to 650 nm, and a FWHM being no greater than 70 nm; or
the second red phosphor having an emission wavelength that is larger than 650 nm and less than or equal to 655 nm, and a FWHM being no greater than 90 nm; or
the second red phosphor having an emission wavelength that is larger than 655 nm and less than or equal to 660 nm, and a FWHM being no greater than 100 nm; or
the second red phosphor having an emission wavelength that is larger than 660 nm and less than or equal to 665 nm, and a FWHM being no greater than 105 nm; or
the second red phosphor having an emission wavelength that is larger than 665 nm and less than 670 nm, and a FWHM being no greater than 110 nm; or
the second red phosphor having an emission wavelength of 670 nm, and a FWHM being no greater than 110 nm.

[0033] The appropriate second red phosphor is selected from those having the emission wavelength and FWHM as described above, in order to improve the color purity of the red phosphor mixed and improve the NTSC color gamut.

[0034] As shown in FIG. 2, the white LED further comprises a leadframe 101, a thermoplastic or thermosetting transparent protective layer, and a fluorescence conversion layer 103 provided on the leadframe 101; the blue LED chip is arranged on the leadframe 101 and is covered by the fluorescence conversion layer 103; the green phosphor and the red phosphor are dispersed in the fluorescence conversion layer 103 which is wrapped up by the thermoplastic or thermosetting transparent protective layer wherein the blue light, the green light and the red light are distributed.

Embodiment 1

[0035] This embodiment provides a red phosphor comprising a first red phosphor and a second red phosphor having adjustable wavelength. The first red phosphor is made from a substance having structure formula M.sub.2AX.sub.6:Mn.sup.4+, wherein the element M is selected from Li, Na, K, Rb or Cs, the element A is selected from Ti, Si, Ge or Zr, and the element X is selected from F, Cl or Br. The ratio of the second red phosphor to the red phosphor is 0.1%. The second red phosphor comprises CaAlSiN.sub.3: Eu. The second red phosphor has an emission wavelength of 660 nm and a FWHM of 90 nm.

[0036] This embodiment provides a white LED comprising the above-described red phosphor, green phosphor and blue LED chip, wherein a red light, a blue light and a green light are mixed simultaneously to produce a white light.

[0037] The red light is emitted by the red phosphor which absorbed the blue light or the green light.

[0038] The green light is emitted by the green phosphor which absorbed the blue light. The green phosphor comprises one or more compound selected from -sialon, silicate, -alon or QD. The green phosphor has wavelength ranging from 510 nm to 550 nm and a FWHM being no greater than 70 nm.

Embodiment 2

[0039] This embodiment provides a white LED whose white light is produced by mixing blue light, green light and red light together. The red light is emitted by the red phosphor which absorbed blue light or green light.

[0040] The blue light emitted by the blue LED chip has an emission wavelength ranging from 430 nm to 460 nm.

[0041] The green light having an emission wavelength of 529 nm and a FWHM of 50 nm is emitted by the green phosphor which absorbed the blue light, wherein the green phosphor is comprised of -sialon.

[0042] The red phosphor comprises a first red phosphor and a second red phosphor, wherein the first red phosphor is made from a substance having structure formula K.sub.2SiF.sub.6:Mn.sup.4+, and the second red phosphor is made from a substance having structure formula SrLiAl.sub.3N.sub.4:Eu whose light emission wavelength is 650 nm and FWHM is 45 nm; wherein the ratio of the second red phosphor to the red phosphor is 5%. With the addition of the second red phosphor to the first red phosphor, the increasing light emission intensity from the red phosphor, compared with the light emission intensity from the first red phosphor before the second red phosphor added, at the emission wavelength ranging from 600 nm to 630 nm will be less than or equal to the increasing light emission intensity from the red phosphor, compared with the light emission intensity from the first red phosphor before the second red phosphor added, at the emission wavelength ranging from 630 nm to 670 nm.

[0043] The blue light, the green light and the red light are distributed in the thermoplastic or thermosetting transparent protective layer.

[0044] The NTSC color gamut of the LED according to this embodiment is reduced by no more than 1% on the basis of the NTSC color gamut of pure K.sub.2SiF.sub.6:Mn.sup.4+.

Embodiment 3

[0045] This embodiment provides a white LED which is extremely similar to the one in the embodiment 2, except the following differences, while their identical parts will not be repeated here.

[0046] The green phosphor is comprised of -alon whose light emission wavelength is 520 nm and FWHM is 35 nm.

[0047] The red phosphor comprises a first red phosphor and a second red phosphor, wherein the first red phosphor is made from a substance having structure formula K.sub.2TiF.sub.6:Mn.sup.4+, and the second red phosphor is made from a substance having structure formula CaAlSiN.sub.3:Eu whose light emission wavelength is 670 nm and FWHM is 90 nm; wherein the ratio of the second red phosphor to the red phosphor is 2%.

[0048] The NTSC color gamut of the LED according to this embodiment is reduced by 1%-2% on the basis of the NTSC color gamut of pure K.sub.2TF.sub.6:Mn.sup.4+.

Embodiment 4

[0049] This embodiment provides a white LED which is extremely similar to the one in the embodiment 2, except the following differences, while their identical parts will not be repeated here.

[0050] The green phosphor is comprised of silicate whose light emission wavelength is 525 nm and FWHM is 70 nm.

[0051] The red phosphor comprises a first red phosphor and a second red phosphor, wherein the first red phosphor is made from a substance having structure formula K.sub.2GeF.sub.6:Mn.sup.4+, and the second red phosphor is made from QD whose light emission wavelength is 640 nm and FWHM is 30 nm; wherein the ratio of the second red phosphor to the red phosphor mixed is 8%.

[0052] The NTSC color gamut of the LED according to this embodiment is reduced by 1%-2% on the basis of the NTSC color gamut of pure K.sub.2GeF.sub.6:Mn.sup.4+.

Embodiment 5

[0053] This embodiment provides a white LED which is extremely similar to the one in the embodiment 2, except the following differences, while their identical parts will not be repeated here.

[0054] The green phosphor is comprised of silicate whose light emission wavelength is 525 nm and FWHM is 70 nm.

[0055] The red phosphor comprises a first red phosphor and a second red phosphor, wherein the first red phosphor is made from a substance having structure formula K.sub.2GeF.sub.6:Mn.sup.4+, and the second red phosphor is made from QD whose light emission wavelength is 640 nm and FWHM is 30 nm; wherein the ratio of the second red phosphor to the red phosphor mixed is 0.06%.

[0056] The NTSC color gamut of the LED according to this embodiment is reduced by %-2% on the basis of the NTSC color gamut of pure K.sub.2GeF.sub.6:Mn.sup.4+.

[0057] The following embodiments further provides a backlight module, including direct-lit backlight module and edge-lit backlight module.

Embodiment 6

[0058] This embodiment uses an existing LED direct-lit backlight module 200, wherein the LEDs are in accordance with the present invention.

[0059] As shown in FIG. 3, the LED direct-lit backlight module 200 comprises a PCB 202, a plurality of optical lenses 201, a lower diffusion sheet 204, a prism sheet 205, an upper diffusion sheet 206 and a backing plate 203. A plurality of LED devices 100 are arranged on the PCB 202, and each of the lenses 201 is arranged on each of the LED devices 100; such PCB 202 is fixed up to the bottom of the backing plate 203, and the lower diffusion sheet 204 is arranged on the top of the backing plate 203; the prism sheet 205 is arranged on the lower diffusion sheet 204 and the upper diffuser sheet 206 is arranged on the prism sheet 205.

Embodiment 7

[0060] This embodiment uses an existing LED edge-lit backlight module 300, wherein the LEDs are in accordance with the present invention.

[0061] As shown in FIG. 4, the LED edge-lit backlight module 300 comprises a light guide plate 303, a reflective sheet 302, a brightness enhancement film 304, and a diffuser film 305. A LED device 100 is secured to a PCB 301 to form an integration which is arranged adjacent to the light guide plate 303. The reflective sheet 302 is arranged underneath the light guide plate 303, and the brightness enhancement film 304 is arranged on the upper surface of the light guide plate 303, and the diffuser film 305 is arranged on the brightness enhancement film 304.

[0062] The embodiment described hereinbefore is merely preferred embodiment of the present invention and not for purposes of any restrictions or limitations on the invention. It will be apparent that any non-substantive, obvious alterations or improvement by the technician of this technical field according to the present invention may be incorporated into ambit of claims of the present invention.

[0063] For the sake of clarity, it is to be understood that the use of a or an throughout this application does not exclude a plurality, and comprise or comprising do not exclude other steps or elements.