JPWO2021018646A5 - - Google Patents

Claims (14)

An LED filament comprising a linear array of LEDs disposed on a support substrate,
wherein the linear array is divided into two separate longitudinal sections, a first longitudinal section comprising only LEDs configured to emit white light having a color temperature , a second longitudinal section comprising only color-controllable LEDs configured to emit color-controllable light, the color-controllable LEDs including LED groups each comprising a red LED, a green LED, and a blue LED, wherein the LEDs within each group are arranged in a non-linear manner;
LEDs within each group are separated by a first intra-group distance and groups are separated by a second inter-group distance, said inter-group distance being greater than said intra-group distance;
LED filament. 2. The LED filament of claim 1, wherein the first longitudinal section has at least two different types of LEDs to emit light of controllable color temperature. 3. The LED filament of claim 1 or 2, wherein said first longitudinal section has a first length and said second longitudinal section has a second length, said first length being greater than said second length, preferably said first length being at least twice as long as said second length. 4. The LED filament of any one of claims 1-3, wherein the LEDs are equidistantly arranged in an array. 5. The LED filament of any one of claims 1-4, wherein the LEDs in the first compartment are covered by an encapsulant comprising a luminescent material. 6. The LED filament of claim 5, wherein said LEDs in said first compartment are controllable to emit white light having a color temperature in the range of 1800-2500K. 7. The LED filament of any one of claims 1-6, wherein the LEDs in the second compartment are covered by an encapsulant comprising a light scattering material. 8. The LED filament of any one of claims 1-7, wherein the support substrate is light transmissive. 9. A retrofit light bulb comprising at least one LED filament according to any one of claims 1 to 8, a transparent envelope at least partially surrounding said LED filament, and a connector for electrically and mechanically connecting said bulb to a socket. 10. The retrofit bulb of Claim 9, further comprising a controller for controlling said LEDs in said first longitudinal section and for controlling said LEDs in said second longitudinal section. 9. A method for controlling an LED filament according to any one of the preceding claims, comprising controlling the color temperature of light emitted by the LEDs in the first compartment and independently controlling the color and/or color temperature of the light emitted by the LEDs in the second compartment. 12. The method of Claim 11, wherein the LEDs in the second compartment are controlled to emit white light. 13. The method of claim 12, wherein the LEDs in the second compartment are controlled to emit white light having the same color temperature as light emitted by the LEDs in the first compartment. 14. The method of claim 13, wherein the LEDs in the first compartment are controlled to emit white light having a relatively warm color temperature and the LEDs in the second compartment are controlled to emit white light having a relatively cool color temperature.