LED-filament and illuminant with LED-filament

1. A filament for a filament lamp comprising a plurality of light emitting semiconductor chips, wherein the light emitting semiconductor chips are located on a carrier board, the light emitting semiconductor chips are electrically connected, and the carrier board is a flexible carrier board,

wherein the flexible carrier board is arranged in a bent shape,

the flexible carrier board is arranged in the form of a helical coil,

the semiconductor chips on a first winding are located at given rotational angles relating to a center line of the coil, and

the semiconductor chips on a second winding are located at rotational angles relating to a center line of the coil different from the given rotational angles on the first winding.

2. The filament according to claim 1 , further comprising a converter that converts a wavelength of light emitted from the light emitting semiconductor chips to light of another wavelength.

3. The filament according to claim 1 , wherein the filament comprises a first electrical connector pad and a second electrical connector pad, and the electrical connector pads each connect to a contact pin.

4. The filament according to claim 1 , wherein the flexible carrier board is a flexible circuit board.

5. The filament according to claim 1 , wherein the flexible carrier board comprises metal circuit paths arranged on top of a flexible polymer film, the polymer film containing polyester (PET), polyimide (PI), polyethylene napthalate (PEN), Polyetherimide (PEI), fluropolymers (FEP) and copolymers thereof.

6. The filament according to claim 1 , wherein the light emitting semiconductor chips are arranged linearly and equally spaced with a distance between centers of two adjoining light emitting semiconductor chips.

7. The filament according to claim 1 , wherein the semiconductor chips on a first winding are located at given rotational angles relating to a center line of the coil, and the semiconductor chips on a second winding are located at rotational angles relating to a center line of the coil in a way that the semiconductor chips on the first winding are located at a position on the first winding corresponding to a position of a center of a gap between two semiconductor chips on the second winding.

8. The filament according to claim 1 , wherein the circumference of a winding of the spiral coil differs from an integer multiple of the distance between the centers of the adjoining light emitting semiconductor chips by an amount of half the distance between the centers of the adjoining light emitting semiconductor chips.

9. An illuminant comprising the filament according to claim 1 , a bulb comprising a transparent material, wherein the filament is located within the bulb, the bulb is filled with a gas, the gas is in contact with the filament and the bulb is closed.

10. The illuminant according to claim 9 , wherein the gas is helium.

11. The illuminant according to claim 9 , wherein a pressure of the gas is 500 to 1200 millibar.

12. A method of producing the illuminant according to claim 9 , comprising:

providing a flexible carrier board with circuit paths;

placing light emitting semiconductor chips on top of the flexible carrier board;

placing the flexible carrier board within a transparent bulb;

filling the bulb with a gas; and

sealing the gas bulb to prevent leaking of the gas from the bulb,

wherein the flexible carrier board is arranged in a bent shape,

the flexible carrier board is arranged in the form of a helical coil,

the semiconductor chips on a first winding are located at given rotational angles relating to a center line of the coil, and

the semiconductor chips on a second winding are located at rotational angles relating to a center line of the coil different from the given rotational angles on the first winding.

13. The method according to claim 12 , wherein a converter is placed before the flexible carrier board is placed.

14. The method according to claim 12 , wherein a converter is placed after the flexible carrier board is brought to a final shape by a spray coating process.