An LED tube lamp comprises a tube, an LED light strip inside the tube, a plurality of LED light sources on the LED light strip, a power supply, and a first and a second end caps. The power supply comprises a circuit board, a plurality of electronic components and a heat-dissipating element. The plurality of electronic components and the heat-dissipating element are on the circuit board. The first end cap and the second end cap are respectively attached at two ends of the tube. The first end cap comprises a lateral wall and an end wall having an opening. The lateral wall is substantially coaxial with the tube and connected to the tube. The end wall is substantially perpendicular to an axial direction of the lateral wall and connected to an end of the lateral wall away from the tube. At least some of the plurality of electronic components and the heat-dissipating element are disposed inside the first end cap. The heat-dissipating element is closer to the opening on the end wall of the first end cap than the electronic components in the end cap are.

A circuit includes a power supply circuit and a ripple reduction circuit. The power supply circuit supplies a Direct Current (DC) lighting current to a light emitting circuit. The lighting current has a ripple current at a ripple frequency. The ripple reduction circuit receives the lighting current, and performs, based on the received lighting current, Pulse Width Modulation (PWM) of the lighting current at a PWM frequency. The PWM frequency is higher than the ripple frequency. By performing the PWM, the ripple reduction current reduces variations in a magnitude of the lighting current at the ripple frequency. The PWM frequency may be higher than a frequency at which variations in the magnitude of the light produced by the lighting circuit have a harmful effect on the human eye.

An indicating circuit for a switching power supply is provided. An LED and a resistor are connected in series, and then are connected in parallel with a capacitor, and the parallel-connected circuit and a diode are connected in series in the same direction, and then are connected in parallel with an inductor to form the indicating circuit. The cathode of the indicating circuit is a terminal 1, and the anode of the indicating circuit is a terminal 2. A charging loop between a rectifying bridge and an electrolytic capacitor for filtering in a fly-back switching power supply is broken to insert the indicating circuit; when the electrolytic capacitor for filtering is normal, an excitation current of a main power stage basically does not appear in the inductor, and the LED does not emit light; when the ESR of the electrolytic capacitor rises greatly, the excitation current of the main power stage appears in the inductor; furthermore, when a switching transistor in the switching power supply is switched off, the excitation current flowing through the inductor may not be changed abruptly, and is freewheeled by the diode; after being filtered by the capacitor, the excitation current drives the LED to emit light; the LED may be a light emitter of a photocoupler to notify a user that: the ESR of the filter capacitor has risen and the switching power supply has a risk of failure, thereby avoiding aggravation of loss; and the indicating circuit has the characteristics of low cost and easiness in implementation.

A direct filtering type switching power supply is provided, for an occasion including pulsating direct current, including a filter circuit, a main power stage and an indicating circuit. A direct current input is connected to the filter circuit through the indicating circuit. The filter circuit and the main power stage are connected in parallel. The indicating circuit is formed by connecting a light emitting unit with an inductor in parallel, and make sure that the direction of the direct current input passing through the inductor is opposite to the conducting direction of the light emitting unit. The filter circuit at least includes an electrolytic capacitor. When the electrolytic capacitor is normal, an excitation current of a switching transistor in the main power stage basically does not appear in the inductor, and an LED in the light emitting unit does not emit light. When the Equivalent Series Resistance of the electrolytic capacitor rises greatly, the excitation current of the switching transistor appears in the inductor. Furthermore, when the switching transistor is switched off, the excitation current flowing through the inductor, which cannot be changed abruptly, freewheels through the LED, and drives the LED to emit light, so as to notify a user or a circuit that the electrolytic capacitor may have the risk of complete failure. The LED may also be a light emitter of a photocoupler. The switching power supply is low in cost, has unchanged efficiency and is easy to implement.

An LED tube lamp comprises a tube, an LED light strip inside the tube, a plurality of LED light sources on the LED light strip, a power supply, and a first and a second end caps. The power supply comprises a circuit board, a plurality of electronic components and a heat-dissipating element. The plurality of electronic components and the heat-dissipating element are on the circuit board. The first end cap and the second end cap are respectively attached at two ends of the tube. The first end cap comprises a lateral wall and an end wall having an opening. The lateral wall is substantially coaxial with the tube and connected to the tube. The end wall is substantially perpendicular to an axial direction of the lateral wall and connected to an end of the lateral wall away from the tube. At least some of the plurality of electronic components and the heat-dissipating element are disposed inside the first end cap. The heat-dissipating element is closer to the opening on the end wall of the first end cap than the electronic components in the end cap are.

An LED tube lamp includes a lamp tube, a heat shrink sleeve covering on an outer surface of the lamp tube, an LED light strip fixed by an adhesive sheet to an inner circumferential surface of the lamp tube, a plurality of LED light sources on the LED light strip, two end caps respectively coupled to two opposite ends of the lamp tube, and a power supply circuit on the light strip. The LED light strip with the plurality of LED light sources and power supply circuit are in the lamp tube.

An LED tube lamp includes a tube having two ends, two end caps respectively at the ends of the tube, a power supply in one or both of the end caps, an LED light strip in the tube; and a plurality of LED light sources on the LED light strip. Each of the end caps comprises a lateral wall substantially coaxial with the tube, an end wall substantially perpendicular to an axial direction of the lateral wall, and at least one opening penetrating through the end wall. An axial direction of the at least one opening is substantially parallel with an axial direction of the lateral wall. The LED light sources electrically connected to the power supply via the LED light strip.

A control circuit includes: a flip-flop having an output configured to be coupled to a control terminal of a transistor and for producing a first signal; a comparator having an output coupled to an input of the flip-flop, and first and second inputs for receiving first and second voltages, respectively; a transconductance amplifier having an input for receiving a sense voltage indicative of a current flowing through the transistor, and an output coupled to the first input of the comparator; a zero crossing detection (ZCD) circuit having an input configured to be coupled to a first current path terminal of the transistor and to an inductor, where the ZCD circuit is configured to detect a demagnetization time of the inductor and produce a third signal based on the detected demagnetization time; and a reference generator configured to generate the second voltage based on the first and third signals.

A light-emitting diode (LED) luminaire comprising two types of LEDs, a switching circuit, a signal generating circuit, and an LED driving circuit is used to replace a conventional luminaire with a severe temporal light artifact. The switching circuit and the LED driving circuit are configured to reduce a low-frequency ripple associated with AC mains. The signal generating circuit is configured to produce two sets of modulation signals with a phase difference of 180 degrees between the two sets of modulation signals, which are then embedded in the LED driving current to drive the two types of LEDs, resulting in imperceptible flicker at a temporal modulation frequency as a result of color mixing of the two types of LEDs and persistence of vision, thereby drastically reducing eyestrain, visual discomfort, etc.