Abstract: An LED lamp includes a bi-direction constant current device coupled between a power supply and a LED load to provide stable positive and negative currents to the LED load. The bi-direction constant current device includes a pair of current sources face-to-face or back-to-back connected in series between the power supply and the LED load, and two protective elements shunt to the pair of current sources, respectively.

Abstract: A bulb shell includes a transparent shell base having an opening, a largest outer diameter and a light projection surface defined by a critical boundary on the shell base, and a coating on the shell base in a region between the opening and the critical boundary to increase brightness of the light projection surface. The critical boundary lies between a first position where the largest outer diameter is located and a second position distant from the first position by 33% of the dimension of the largest outer diameter in a direction away from the opening. The coating will significantly increase the brightness of the light projection surface when the bulb shell is used in a LED light bulb.

Abstract: An LED lamp includes a bi-direction constant current device coupled between a power supply and a LED load to provide stable positive and negative currents to the LED load. The bi-direction constant current device includes a pair of current sources face-to-face or back-to-back connected in series between the power supply and the LED load, and two protective elements shunt to the pair of current sources, respectively.