LED fluorescent lamp emulator circuitry

Abstract

Circuitry 31 for a solid-state lighting arrangement 20 designed for as a replacement for a gas discharge lamp used in a lighting fixture having a ballast. The circuitry 31 unsafe flow of current through the solid-state lighting arrangement 20, under non-operational conditions and during installation of the lighting arrangement, so as to provide compatibility with safety standards for use with discharge lamps.

Claims

1. A solid-state lighting arrangement for use within a lighting fixture having ballast circuitry capable of powering at least one gas discharge lamp, the arrangement comprising: inputs adapted for coupling to lamp connections within the lighting fixture; a solid-state light source operably coupled to the inputs; and AC switching circuitry, operably coupled to the inputs, to preclude current flow through the solid-state light source of greater than 5 milliamperes or 7.07 milliamperes peak, when voltage applied to the inputs is less 170 Vac rms; wherein the AC switching circuitry comprises a capacitor and a triac operably connected in series with one of two bipins of a bipin connector of the solid-state light source through a junction of two diodes connected together and a second anode of the triac; and wherein the capacitor is connected in parallel to a gate and a first anode of the triac, and wherein a second pin of the bipins is connected with a combination of components in series to a gate of the triac, wherein the combination of components in series from the first bipin and the gate form a AC voltage divider with the capacitor between the gate and the first anode of the triac which is also connected to the second pin of the bipins, and wherein the triac, being non-conductive, prevents current flow through the solid-state light source, and thereby prevents current flow greater than 5 milliamperes or 7.07 milliamperes peak when voltage is applied to the inputs less than 170 vac rms.

2. The solid-state lighting arrangement of claim 1, further comprising a diode and a fourth capacitor operably connected between the first of the two input pins of the bipin connector and the second anode of the triac.

3. A solid-state lighting arrangement for use within a lighting fixture having ballast circuitry capable of powering at least one gas discharge lamp, the arrangement comprising: inputs adapted for coupling to lamp connections within the lighting fixture; a solid-state light source operably coupled to the inputs; and AC switching circuitry, operably coupled to the inputs, to preclude current flow through the solid-state light source of greater than 5 milliamperes or 7.07 milliamperes peak, when voltage applied to the inputs is less 170 Vac rms; wherein the AC switching circuitry comprises a capacitor and a triac operably connected between two input pins of a bipin connector in series with one of two bipins of a bipin connector of the solid-state light source through a junction of two diodes connected together and a second anode of the triac; and wherein the capacitor is connected in parallel to a gate and a first anode of the triac, and wherein a second pin of the bipins is connected with a combination of components in series to a gate of the triac, wherein the combination of components in series from the first bipin and the gate form a AC voltage divider with the capacitor between the gate and the first anode of the triac which is also connected to the second pin of the bipins, and wherein the triac, being non-conductive, prevents current flow through the solid-state light source, and thereby prevents current flow greater than 5 milliamperes or 7.07 milliamperes peak when voltage is applied to the inputs less than 170 vac rms, and wherein the AC switching circuitry further comprises a thermistor connected in parallel with the capacitor.

4. The solid-state lighting arrangement of claim 3, further comprising a diode and a second capacitor operably connected between a second anode of the triac and a first of the two input pins of the bipin connector.

5. The solid-state lighting arrangement of claim 1, further comprising: a first combination of a first resistor and a second capacitor connected in parallel; a second combination of a second resistor and a third capacitor connected in parallel; wherein the first combination of the first resister and the second capacitor is connected in series with the second combination of the second resister and the third capacitor; and wherein the first combination of the first resister and the second capacitor and the second combination of the second resister and the third capacitor are operably connected between the first of the two input pins of the bipin connector and the gate and the first anode of the triac.

6. The solid state lighting arrangement of claim 3, wherein the first anode of the triac is operably connected to the second of the two input pins of the bipin connector.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The features, aspects and advantages of the present invention will become better understood with regard to the following description, appended claims and accompanying figures wherein:

(2) FIG. 1 is a block-diagram illustrating a solid-state lighting arrangement and a lighting fixture that includes a ballast.

(3) FIG. 2 is an electrical schematic of a typical LED replacement lamp.

(4) FIG. 3 is an electrical schematic of an LED replacement lamp with an AC switch controlled by filament voltage across the bipins.

(5) FIG. 4 is an electrical schematic illustrating implementing AC switching according to the present invention through use of a triac.

(6) FIG. 5 is an electrical schematic illustrating implementing AC switching according to the present invention through use of a thermistor to emulate the change in resistance due to self-heating and providing additional delay in conductance through the lamp.

(7) FIG. 6 is an electrical schematic illustrating implementing AC switching according to the present invention that will still provide full emulation of a fluorescent lamp when operating with an instant start ballast.

DETAILED DESCRIPTION

(8) In the following description of the preferred embodiments, reference is made to the accompanying drawings which show by way of illustration specific embodiments in which the invention may be practiced. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. It is to be understood that other embodiments may be utilized and structural and functional changes may be made without departing from the scope of the present invention.

(9) FIG. 1 depicts a solid-state lighting arrangement 10 that is intended as a drop-in discharge lamp replacement for use within an existing lighting fixture 100.

(10) As described in FIG. 1, lighting fixture 100 includes lamp connections 102, 104 (between which one or more lamps are usually connected) and ballasting circuitry 110 (which typically receives a conventional source 112 of AC power, such as 120 volts rms at 60 hertz).

(11) During operation, ballasting circuitry 110 provides a suitable source of electrical power between lamp connections 102, 104 for igniting and powering one or more discharge lamps.

(12) Referring again to FIG. 1, solid-state lighting arrangement 10 has inputs 12,14,16,18 which are suitable for connection to lamp connections 102,104 within lighting fixture 100.

(13) FIG. 2 illustrates a schematic view of an embodiment of the solid-state lighting arrangement 10, including input Pin_1, 12 Pin_2, 14 Pin_3, 16 and Pin_4 18. The arrangement includes resistors 22 to emulate filament resistance and fuses 24 for safety. Lighting is produced by solid-state light source 20 comprising a series of Light Emitting Diodes (LEDs) configured between the two sets of input pins 12, 14, 16, 18 when current flows between Pin_1/Pin_2 12/14 and Pin_3/Pin_4 16/18.

(14) A variation of the solid-state lighting arrangement 10 from FIG. 2, is shown in FIG. 3. In this variation, safety requirements, may be met by the inclusion of a circuitry 31, 32 to perform filament sensing and switching out Pin_1 12 and Pin_2 14 and/or Pin_3 16 and Pin_4 18, until safe and sufficient filament voltage is sensed and the switches 33, 34 which separate the two sets of bipins, Pin_1 12 and Pin_2 14; and Pin_3 16 and Pin_4 18 are closed, allowing current to flow through the solid-state light source 20.

(15) A practical embodiment of such a circuit 31 is shown, schematically, in FIG. 4. Although in FIGS. 4 through 6, only the circuitry associated with Pin_1 12 and Pin_2 14 is shown, it is understood that the corresponding circuitry is also found associated with Pin_3 16 and Pin_4 18. When the filament voltage is applied between Pin_1 12 and Pin_2 14 voltage will appear across capacitor C1 41 that will trigger triac 42, if above threshold. Before the triac 42 is triggered, the resistance between anodes, A1 and A2, is high limiting any current flow. After the gate is triggered the impedance between anodes A1 and A2 of triac 42 drops, conducting current from Pin_2 14 through the triac 42 to light the solid-state light source (not shown). If either Pin_1 12 or Pin_2 14 are open, there is no path for the gate current to turn on the triac 42.

(16) During tests, such as the UL935 thru lamp leakage test, one of the pins on the lamp is opened and no current will flow thru the lamp. Such a test simulates installation of a lamp when the ballast is energized so this provides protection for the installer. Resistors, R1 43 and R2 44 simulate the filament current circuit thru the gate and capacitor, C1 41 in parallel. An additional resistor may be added in series with the gate of the triac 42 if the gate can't sustain full filament current. In addition, an additional passive component across capacitor, C1, 41, can shunt excessive current. The value of capacitance for capacitor C1, 41, can determine a small delay before the solid-state light source 20 (not shown in FIGS. 4 and 5) illuminates. FIG. 5 illustrates a circuit in which additional delay is achieved by emulating the change in resistance due to self-heating, by use of a thermistor 51.

(17) The AC switch circuits described above and illustrated in FIGS. 4 and 5, will operate to provide solid-state illumination for magnetic rapid start ballasts as well as high-frequency electronic program start ballasts. In addition, the AC switch circuitry will beneficially prevent current flow thru the solid-state light source if any pin in the lamp is open, providing protection from electrical shock.

(18) FIG. 6 illustrates switch circuitry which will operate with another type of high-frequency electronic ballast for fluorescent lamps, known as an instant start ballast. Instant-start ballasts allow for illumination of traditional fluorescent lights without the delay for filament heating, by applying voltage across the lamp at above the ionization voltage without waiting for filament heating. The gas ionizes immediately to a plasma and creates light in the fluorescent lamp without delay.

(19) When using LED lamp on instant start ballast, the lamp will light as soon as the applied ballast voltage is above the voltage of the series diodes. The ballast limits the current in to the LED that are turned on. The instant start ballast is isolated from the main voltage and ground so little current will flow thru the LED lamp when one end of the lamp is lifted out of the connector. The only coupling to ground is thru the capacitance of the isolation transformer inside the ballast. The current to ground is limited. Since the frequency and voltage across the lamp are high, current may flow when an open end of the lamp is connected the circuit during the UL935 test. Depending on conditions, this current could exceed 5 ma rms, and fail the test. In normal operation on the instant start ballast, the LED AC switch would prevent the lamp from lighting because of lack of filament voltage.

(20) FIG. 6 schematically illustrates an AC switching circuit 31 in which the triac 42 may be triggered multiple ways. The emulation of filament heating provides gate voltage and current between anode A1 and the gate of the triac 42. If anode A1 of triac 42 is connected to the gate thru a resistor, the triac 42 will turn on if there is positive voltage on anode A2 of the triac 42. Adding a diode D1 61 and capacitor C4 62 as illustrated in FIG. 6, provide the positive voltage needed to trigger the connection between anode A2 and the gate of triac 42. The value of capacitor C4 62 may be adjusted so the voltage of an instant ballast will turn on the triac 42 when normally connected but prevent the turn on with the lower lamp voltage applied in the magnetic and high frequency ballast with filament heating. The lamp can be used universally on all ballast types and pass the requirement of UL935 if the ballast also passes on fluorescent lamps.

(21) Any element in a claim that does not explicitly state “means” for performing a specified function or “step” for performing a specified function, should not be interpreted as a “means” or “step” clause as specified in 35 U.S.C. § 112.