High-efficiency LED light bulb with LED filament therein
An high-efficiency light bulb, comprising: a lamp housing with inner surface and outer surface opposite to the inner surface of the lamp housing, the lamp housing includes a layer of luminescent material, which is formed on the inner surface or the outer surface of the lamp housing or integrated in the material of the lamp housing; a bulb base connected to the lamp housing; a stem connected to the bulb base and located in the lamp housing; and a single filament, disposed in the light housing, further comprising a plurality of supporting arms, connected with and supporting the LED filament, wherein the stem comprises a stand extending to the center of the lamp housing, the stand supports the supporting arms.
1. An high-efficiency light bulb, comprising:
a lamp housing with inner surface and outer surface opposite to the inner surface of the lamp housing, the lamp housing includes a layer of luminescent material which is formed on the inner surface or the outer surface of the lamp housing or integrated in the material of the lamp housing;
a bulb base connected to the lamp housing;
a stem connected to the bulb base and located in the lamp housing; and
an LED filament disposed in the light housing, the LED filament comprising:
a plurality of LED filament units, wherein each of the plurality of LED filament units includes a single LED chip with an upper surface and a lower surface opposite to the upper surface of the LED chip, and
a light conversion layer comprising a top layer and a base layer, wherein the base layer comprises an upper surface and a lower surface opposite to the upper surface of the base layer, the top layer with an upper surface and a lower surface opposite to the upper surface of the top layer is disposed on at least two sides of each of the LED chips, the lower surface of each of the LED chips is close to the upper surface of the base layer, the upper surface of the top layer is away from each of the LED chips;
two conductive electrodes disposed on the base layer of the light conversion layer, where the light conversion layer is coated on at least two sides of at least two LED chips and the two conductive electrodes and a portion of each of the two conductive electrodes is not coated with the light conversion layer;
wherein W 1 represents the width of the upper surface of the base layer or the width of the lower surface of the top layer in the short axial direction of the LED filament, and W 1 is between W 2 /0.9 and d, where d represents the minimum of 10C tan 0.5β/tan 0.5α and 2H tan 0.5β, and W 2 represents the width of the LED chip, and H represents the distance from the upper surface of each of the LED chips to the upper surface of the top layer, where a represents the illumination angle of each of the LED chips in the longitudinal direction of the LED filament, and C represents the length of the LED filament unit in the longitudinal direction of the LED filament; where β represents the illumination angle of each of the LED chips in the short axial direction of the LED filament;
wherein at least two LED filament units of the LED filament have respective current paths when the at least two LED filament units are electrically connected in parallel, and cathodes of the at least two LED filament units are electrically connected together to serve as a negative electrode of the light emitting part and anodes of the at least two LED filament units serve as a first positive electrode and a second positive electrode, respectively;
wherein the base layer of the light conversion layer is formed from organosilicon-modified polyimide resin composition comprising an organosilicon-modified polyimide and a thermal curing agent, wherein the organosilicon-modified polyimide comprises a repeating unit represented by the following general formula (I):
wherein Ar 1 is a tetra-valent organic group having a benzene ring or an alicyclic hydrocarbon structure, Ar 2 is a di-valent organic group having a monocyclic alicyclic hydrocarbon structure, R is each independently methyl or phenyl, n is 1-5;
wherein the organosilicon-modified polyimide has a number average molecular weight of 5000-100000; and
wherein the thermal curing agent is selected from the group consisting of epoxy resin, isocyanate and bisoxazoline compounds.
2. The light bulb of claim 1 , wherein W 1 is between W 2 /0.9 and D, where D represents the minimum of 2C tan 0.5β/tan 0.5α and 2H tan 0.5β.
3. The light bulb of claim 1 , wherein W 1 is between 1.1W 2 and e, where e represents the minimum value of 10C and 3.46H.
4. The light bulb of claim 1 , wherein W 1 is between 1.1W 2 and E, where E represents the minimum value of 2C and 3.46H.
5. The light bulb of claim 4 , wherein the LED filament comprise LED sections and conductive sections for electrically connecting adjacent two LED sections.
6. The light bulb of claim 5 , wherein each of the LED sections includes at least two LED chips that are electrically connected to each other by a wire, the shortest distance between the two LED chips respectively located in the two adjacent LED sections is greater than the distance between two adjacent LED chips within one of the LED sections.
7. The light bulb of claim 6 , wherein each of the conductive sections includes at least one conductor that connects the adjacent LED sections, and the length of the wire is less than the length of the conductor.
8. The light bulb of claim 7 , further comprising a plurality of supporting arms connected with and supporting the LED filament, wherein the stem comprises a stand extending to the center of the lamp housing, and the stand supports the supporting arms.
9. The light bulb of claim 8 , wherein Ar 1 is a tetra-valent organic group having a monocyclic alicyclic hydrocarbon structure or a bridged-ring alicyclic hydrocarbon structure.
10. The light bulb of claim 9 , wherein Ar 2 is a di-valent organic group comprising a functional group having active hydrogen, where the functional group having active hydrogen is any one of hydroxyl, amino, carboxy and mercapto.
11. The light bulb of claim 10 , wherein Ar 1 is derived from a dianhydride, and Ar 2 is derived from a diamine.
12. The light bulb of claim 11 , wherein the organosilicon-modified polyimide resin composition further comprises an additive selected from the group consisting of fluorescent powders, heat dispersing particles and a coupling agent.
13. The light bulb of claim 12 , wherein the organosilicon-modified polyimide resin composition further comprises one or more of a defoaming agent, a leveling agent and an adhesive.
14. The light bulb of claim 13 , wherein the heat dispersing particles have a particle size distribution of 0.1-100 μm.
15. The light bulb of claim 14 , wherein the content of small particle size of below 1 μm is 5-20%, the content of medium particle size of 1-30 μm is 50-70%, and the content of large particle size of above 30 μm is 20-40%.
16. The light bulb of claim 15 , wherein the fluorescent powders have an average particle size from 1 μm to 50 μm.
17. The light bulb of claim 16 , wherein the organosilicon-modified polymide composition has a refractive index of 1.4-1.7.
18. The light bulb of claim 17 , wherein the base layer has an elastic modulus of more than 2.0 GPa, and an elongation at break of more than 0.5%.
19. The light bulb of claim 18 , wherein the heat dispersing particles are in a shape of sphere or non-sphere, the added weight ratio of the spherical and non-spherical heat dispersing particles is 1:0.15-0.35.
20. The LED filament light bulb of claim 19 , wherein points of the LED filament in an xyz coordinates are defined as X, Y, and Z and satisfy a curve equation, an origin of xyz coordinates is at the stem top, an x-y plane of the xyz coordinates passes through the stem top and is perpendicular to the height direction, a z-axis of xyz coordinates is coaxial with stem, and the two conductive electrodes are symmetrically disposed at two sides of a y-axis of the xyz coordinates, the curve equation is:
X=m 1*cos( t* 360),
Y=m 2*sin( t* 360),
Z=n *cos( t* 360* k ),
Wherein, t is a variable between 0 and 1, the LED filament varies along an x-direction, a y-direction, and a z-direction according to t; wherein, when X=0, a max value of |Y| is m2, and a max value of |Z| is n; wherein, when Y=0, a max value of |X| is m1, and a max value of |Z| is n; wherein, when Z=0, a max value of |X| is m1, and a max value of |Y| is m2; wherein m1 is a length in the x-direction, m2 is a length in the y-direction, n is a height of the highest point from the x-y plane in the z-direction, and k is a number of the highest point.