Patent ID: 8643278

Claim:
A tubular light, comprising: a light tube; a circuit board disposed in the light tube; at least one illuminating element disposed on the circuit board; and a transformer disposed on the circuit board and electrically connected to the at least one illuminating unit, the transformer comprising: a core unit having a pair of opposingly arranged base portions, an inserting portion, and a pair of opposingly arranged lateral portions, wherein the inserting portion has a long axis, the inserting portion and the lateral portion extend from the base portion substantially along the long axis, wherein the top-facing edge of the lateral portions is chamfered, wherein the lateral portion is spaced from the inserting portion, defining a pair of coil winding space there-between for passing coils; and at least a primary coil and a secondary coil wound around the inserting portion, wherein the primary coil has a primary coil winding number (N p ) while the secondary coil has a secondary coil winding number (N s ), the ratio of N p and N s defines a coil winding ratio (N), wherein the N p and N are selectively determined from the solution space of a characteristic effective area function A e (N p , N) and a characteristic magnetic flux variation function ΔB(N p , N), which are provided by applying predetermined operational and material specifications to a characteristic equation: A e = V i ⁢ ⁢ n ⁢ ⁢ _ ⁢ ⁢ m ⁢ ⁢ i ⁢ ⁢ n ⁢ D ⁡ ( V i ⁢ ⁢ n ⁢ ⁢ _ ⁢ ⁢ m ⁢ ⁢ i ⁢ ⁢ n , N , V 0 ) N p ⁢ Δ ⁢ ⁢ B · fre wherein A e denotes an effective cross-sectional area of an inserting portion, V in — min denotes minimum AC (alternating current) input voltage in [V], N denotes winding ratio between primary and secondary windings, V o denotes DC output voltage in [V], D (V in — min , N, V o ) denotes duty cycle, wherein D 1 - D = N ⁢ ⁢ V 0 V i ⁢ ⁢ n ⁢ ⁢ _ ⁢ ⁢ m ⁢ ⁢ i ⁢ ⁢ n , Np denotes primary winding number, ΔB denotes change in magnetic flux density in [Tesla], fre denotes operating frequency in [KHz], wherein a coil winding width (W) of the transformer is defined between the inserting portion and each of the lateral portions, wherein a coil winding length (L) of the transformer is obtained by dividing a total required coil winding area (A total ) by the coil winding width (W), wherein the total required coil winding area (A total ) is calculated from the N p and N s .