Led filament light bulb

An LED filament 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, 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;
• wherein C represents the length of the LED filament unit in the longitudinal direction of the LED filament, and C is between f and 4H tan 0.5α, where f represents the maximum value of both 0.2H tan 0.5α and 0.1W1 tan 0.5α/tan 0.5β, 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 W1 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;
• where β represents the illumination angle of each of the LED chips in the short axial direction of the LED filament;
• 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 Ar1 is a tetra-valent organic group having a benzene ring or an alicyclic hydrocarbon structure, Ar2 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.