Linear solid-state lighting with electric shock current sensing
A linear light-emitting diode (LED)-based solid-state lamp comprises an LED driving circuit, LED arrays, at least one rectifier, and an operation monitoring module. The LED driving circuit comprises a current sensing device that is originally used to precisely control an electric current to flow into the LED arrays. The operation monitoring module uses the same current sensing device in a way that it detects an electric shock current and determines if the linear LED-based solid-state lamp is operated in a normal mode or in an electric shock hazard mode. When an electric shock hazard is identified, the operation monitoring module shut off a return current flow from the LED arrays to reach the at least one rectifier, thus eliminating an overall through-lamp electric shock current. The scheme can effectively reduce a risk of electric shock hazard to users during relamping or maintenance.
1. A linear light-emitting diode (LED) tube lamp, comprising:
a housing having two ends;
a plurality of LED arrays disposed between the two ends of the housing;
an LED driving circuit comprising a current sensing device coupling to the LED arrays;
two lamp bases respectively connected to the two ends of the housing, each lamp base comprising at least one electrical conductor configured to insert into a respective lamp fixture socket;
at least one rectifier configured to convert an alternate current (AC) voltage to a direct current (DC) voltage; and
an operation monitoring module receiving a signal from the current sensing device in the LED driving circuit,
wherein:
when a through-lamp electric shock current is detected by the current sensing device, the operation monitoring module disconnects an electric current return from the LED arrays from reaching the at least one rectifier; and
when the at least one electrical conductor in each lamp base is inserted into the respective lamp fixture socket, the operation monitoring module enables the LED driving circuit to deliver electrical power to the LED arrays.
2. The linear LED tube lamp of claim 1 , wherein the operation monitoring module is configured to receive power from the at least one rectifier.
3. The linear LED tube lamp of claim 1 , wherein the current sensing device in the LED driving circuit is configured to receive the electric current return from the LED arrays to perform acts comprising:
controlling: the LED arrays in a constant current mode;
detecting the electric current return from the LED arrays; and
sending a detection signal to the operation monitoring module.
4. The linear LED tube lamp of claim 3 , wherein a predetermined electric current return from the LED arrays is preset such that the operation monitoring module operates the linear LED tube lamp with AC mains at voltages/frequency in a range of or at 100˜277 V/60 Hz or with electronic ballasts at voltages/frequency in a range of 350˜600 V/40˜60 kHz.
5. The linear LED tube lamp of claim 1 , wherein the operation monitoring module comprises an error amplifier, a power up control, a logic control, a switch control section, and at least one switch configured to connect or disconnect the electric current return from the LED arrays.
6. The linear LED tube lamp of claim 5 , wherein the error amplifier is configured to receive a signal from the current sensing device through a peak detector, create an error signal associated with a measured voltage from the peak detector and a preset voltage, and send the error signal to the logic control subsequently controlling the switch control section to switch on the at least one switch when the error signal is not detected or to switch off when the error signal is detected.
7. The linear LED tube lamp of claim 6 , wherein the logic control comprises an one-bit memory configured to latch the at least one switch.
8. The linear LED tube lamp of claim 5 , wherein the error amplifier is connected to a capacitor.
9. The linear LED tube lamp of claim 5 , wherein electrical contacts of the at least one switch comprise electrical terminals of at least one relay.
10. The linear LED tube lamp of claim 9 , wherein the at least one relay comprises a solid-state relay, an electronic relay, or an electro-mechanical relay.
11. The linear LED tube lamp of claim 5 , wherein electrical contacts of the at least one switch comprise electrical terminals of at least one triac.
12. The linear LED tube lamp of claim 5 , wherein electrical contacts of the at least one switch comprise electrical terminals of at least one electronic switch.
13. The linear LED tube lamp of claim 12 , wherein the at least one electronic switch comprises a metal-oxide-semiconductor field-effect transistor (MOSFET), a field-effect transistor (FET), a transistor, a back-to-back thyristor, a silicon-controlled rectifier (SCR), or a combination thereof.
14. The linear LED tube lamp of claim 1 , wherein the operation monitoring module further comprises a voltage detection circuit configured to determine whether an input voltage is in a range of 100-120 V or 270-285 V from AC mains, or in a range of 350˜600 V from an electronic ballast.
15. The linear LED tube lamp of claim 14 , wherein the voltage detection circuit is configured to provide a preset voltage to the error amplifier.