LED lamp device with SVM reduction circuit

Abstract

An LED lamp arrangement (100) for replacing a fluorescent lamp in a lighting device equipped with an electronic ballast is provided. The LED lamp arrangement (100) comprises a plurality of LEDs (101, 102, 103), an SVM reduction circuit (110) comprising an energy storage device connected across the plurality of LEDs (101, 102, 103), and a metrology circuit (120) adapted to measure a current drawn from the electronic ballast and to generate an output to the SVM reduction circuit (110). Based on the output, the measure and control circuit (120) is configured to activate the SVM reduction circuit (110) when the current drawn from the electronic ballast exceeds a threshold and to deactivate the SVM reduction circuit (110) when the current drawn from the electronic ballast does not exceed the threshold.

Description

Technical Field

[0001] The present invention relates generally to light emitting diode (LED) lamps and LED lighting, and more particularly to LED lamps suitable for replacing fluorescent lamps in lighting fixtures. Background Art

[0002] Fluorescent lighting has been around for many years. This form of lighting began as an efficient replacement for incandescent light bulbs, but has recently been surpassed by LED lighting in terms of efficiency and power consumption, as well as other aspects discussed below.

[0003] A fluorescent lamp generally comprises a tube filled with an inert gas and a small amount of mercury, with both ends covered with double fixed end caps. The end caps contain a hot wire to preheat the gas inside the tube and evaporate the mercury to assist in the starting of the fluorescent lamp. After the user turns on the main switch (e.g., a wall switch or a wire switch on the ceiling), the fluorescent lamp starts, and the heat generated by the conducted current keeps the fluorescent lamp in operating condition. In order to facilitate the starting of the lamp and limit the current through the lamp during operation, and thereby limit the power consumed, a ballast is generally installed in the fluorescent lighting device, connected between the main power supply and the fluorescent lamp, and the electrical energy is supplied to the lamp via the ballast.

[0004] When first introduced, the only ballasts available were simple inductive or reactive elements placed in series with the fluorescent lamp power supply, which limited the power consumed by limiting the AC current due to the frequency-dependent impedance of the inductor. These types of ballasts are often referred to as magnetic ballasts.

[0005] Other types of ballasts, such as electronic ballasts, have recently been introduced. These ballasts typically first convert AC mains power to DC power, and then convert the DC power to high frequency AC power to drive the fluorescent lamp (e.g., 100-110 V alternating current with a frequency in the range of 20 kHz to 70 kHz).

[0006] Electronic ballasts can also be divided into two types: constant current ballasts and constant power ballasts. Most electronic ballasts are constant current ballasts, which are designed to deliver current at a substantially constant amplitude. These ballasts can be modeled as a constant AC current source. Constant power ballasts deliver power close to the original fluorescent lamp power, and the output current will vary depending on the load to maintain the design power output. If the load voltage is below the design level, the constant power ballast usually approaches the design power level by increasing the output current.

[0007] LED lamps are more efficient than fluorescent lamps and have many other advantages. For example, LED lamps do not require mercury, the light output from an LED lamp is more directional, the power can be more easily controlled or adjusted, and the lifespan of an LED is generally much longer than a fluorescent lamp. Therefore, it is often desirable to replace a fluorescent lamp with an LED lamp, and it is also desirable to be able to fit a replacement LED lamp into a lighting fixture without modifying an existing lighting fixture designed for a fluorescent lamp. However, LED lamps generally operate differently when used with different types of ballasts. In some cases, directly replacing a fluorescent lamp with an LED lamp in a fluorescent lighting fixture can cause the entire lighting fixture to fail.

[0008] An LED lamp device that is compatible with all three types of ballasts (magnetic ballasts, constant current ballasts, and constant power ballasts) described above, as well as when the lighting device does not have a ballast (e.g., a lighting device originally designed for a fluorescent lamp, but whose ballast has been removed because it is too old or damaged), is described in Applicant's U.S. Patent No. 10342079, which is incorporated by reference in its entirety. The LED lamp has: a switch-mode power supply for driving the LED; a ballast protection circuit including an inductor; and one or more sensing circuits for generating at least one output based on power received from the lighting device indicating whether the power is generated via a magnetic ballast, generated via a constant current ballast, generated via a constant power ballast, or generated without a ballast. The lamp also has a plurality of switches for defining a plurality of operating modes of the LED lamp, wherein components of the lamp (e.g., a switch mode power supply and a ballast protection circuit) are connected or disconnected in different ways, and for switching between the plurality of operating modes based on at least one output of a sensing circuit, which indicates that electrical energy is generated via a magnetic ballast, a constant current ballast, or a constant power ballast or is not generated via the ballast.

[0009] In addition to the electrical issues discussed above, optical issues can also arise when replacing fluorescent lamps with LED lamps. In fluorescent lamps, thermal inertia slows down changes in light output levels under varying power conditions, so these changes are generally not visible. In contrast, LEDs are semiconductor sources that respond quickly to changing power parameters. This rapid change can cause some optical problems, such as flicker.

[0010] Flicker is a periodic, rapid and directly visible change in the brightness of a light source, which can be caused by fluctuations in the light source. Flicker can cause visual discomfort at work. It can also cause migraines and even epileptic seizures.

[0011] The applicant describes an LED lamp that deals with the flicker problem in European patent EP3449694 B1, the entire contents of which are incorporated herein by reference. The LED lamp comprises a flicker reduction circuit and a detector for distinguishing between an electronic ballast and a magnetic ballast based on the voltage and / or current supplied to the lamp by the ballast, and a switch control circuit that controls a switch to connect the flicker reduction circuit in parallel to the LED (after a delay period after lamp start) only if the lamp is energized by a magnetic ballast, while preventing such connection when the ballast is an electronic ballast. This is based on the recognition that a capacitor in a flicker reduction circuit with a capacitor in an LED lamp can cause a safety mechanism in an electronic ballast not to energize the lamp. On the other hand, flicker is a problem for magnetic ballasts operating at relatively low frequencies, but is generally not a problem for electronic ballasts operating at high frequencies.

[0012] Another optical problem known as the stroboscopic effect has received increasing attention recently. This problem concerns the disturbance of the perception of moving objects, for example how fast an object is rotating. The light intensity fluctuations of a light source can be seen as a series of "snapshots" taken according to a certain sampling rate. Depending on the rotation speed of the object and this sampling rate, the object may appear to be stationary or even appear to rotate in the opposite direction in some cases. This disturbance may cause the user to have a false impression of the object's motion and / or rotation, sometimes even leading to accidents.

[0013] At the end of 2021, a new EU regulation EU2019 / 2020 (Ecodesign) came into force. This regulation sets new requirements for electrical equipment including LED light sources. In addition to some new energy efficiency classes, this regulation introduces a new requirement to limit the flicker effect, expressed as a parameter "Stroboscopic Visibility Measurement (SVM)". This parameter can be objectively measured according to the IEC TR 63158:2018 standard. The new EU regulation has implemented a phase-out plan requiring an SVM level of less than 0.9 from September 2021, with the ultimate goal of less than 0.4 from September 2024.

[0014] Unlike flicker, electronic ballasts may still have high SVM values ​​even at high frequencies. SVM can be reduced by using similar flicker reduction circuits, for example, using capacitors connected across the LEDs, but as mentioned above, applying such circuits will result in incompatibility with electronic ballasts. Summary of the invention

[0015] It is therefore an object of the present invention to provide an LED lamp which can operate reliably at low SVM while ensuring compatibility with electronic ballasts.

[0016] A first aspect of the present invention relates to an LED lamp device which is at least suitable for (but not limited to) replacing a fluorescent lamp in a lighting device equipped with an electronic ballast. In an embodiment, the LED lamp device comprises:

[0017] - Multiple LEDs; - an SVM reduction circuit comprising an energy storage device (eg, a capacitor) connected across the plurality of LEDs; and - a measurement and control circuit adapted to measure the current drawn from the electronic ballast and generate an output to the SVM step-down circuit directly or via one or more other components; In an embodiment, based on the output, the measurement and control circuit is configured to activate the SVM reduction circuit when the current drawn from the electronic ballast exceeds a threshold value, and to deactivate the SVM reduction circuit when the current drawn from the electronic ballast does not exceed the threshold value. The SVM reduction circuit may be in a deactivated state by default, in which case deactivating the SVM reduction circuit should be understood to cover the situation in which the SVM reduction circuit remains deactivated, for example, by not outputting any signal through the measurement and control circuit.

[0018] The present invention is based on the recognition that not all electronic ballasts require an SVM reduction circuit and that the current drawn from the ballast can be used as an indicator of whether such a circuit is required. This recognition is based on an in-depth study of the internal structures of various types of ballasts and a series of tests performed by the inventors.

[0019] Constant current ballasts typically have an active boost converter in them that converts the main AC voltage from the wall (e.g., 230V) to a higher DC voltage (e.g., 400 V). This 400 V DC typically has a relatively small current ripple (2%-5%) at 100 Hz. The role of this boost converter is to achieve a relatively high power factor and low harmonic current distortion. There is an inverter circuit after the boost converter that converts the 400 V DC to a high frequency (e.g., 45 kHz). This high frequency current envelope has the same 2%-5% 100 Hz ripple. The inventors have developed a theory that an LED lamp can achieve an inherent SVM of less than 0.4 using the active boost converter present in a constant current ballast, without relying on additional SVM reduction circuitry in the fixture, and have verified this theory through testing.

[0020] Constant power ballasts usually do not have a boost stage. This type of ballast uses a passive circuit (called a valley fill circuit) to achieve a relatively low power factor. This results in a higher ripple, typically 15%-20% current ripple. After the valley fill circuit there is the same inverter inverter circuit as the constant current ballast, which produces a high frequency, but the current envelope still contains the same 15%-20% 100 Hz ripple. This ripple results in a relatively high SVM despite the high ballast frequency. Therefore, when the ballast is a constant power ballast, the LED lamp needs a circuit to absorb this ripple (for example, using a capacitor). The inventors have also determined the cause of the incompatibility with this circuit. According to the inventors' research, this seems to lie in the intelligent controller inside the electronic ballast. This intelligent controller monitors two parameters called ballast preheat frequency and ballast preheat current. The preheat mode frequency corresponds to the frequency of the ballast current during lamp startup. When the controller detects that this frequency deviates significantly from the value preset in the ballast, the controller detects a fault and shuts down the electronic ballast. Similarly, the smart controller monitors the current during startup. If the current drawn from the ballast becomes too high, the smart controller detects the fault and shuts itself down. Incidentally, this smart controller is only present in constant current ballasts, presumably to provide ideal operating conditions for fluorescent lamps.

[0021] Combining these, it is possible to operate in two modes, enabling low SVM for both types of electronic ballasts. This enables the LED lamp device to operate in a first operating mode when the ballast is a constant current ballast, and in a second operating mode when the ballast is a constant power ballast.

[0022] In the first operating mode, the LED lamp device can utilize the existing boost stage circuit present in the ballast to achieve a low SVM value without relying on an additional SVM reduction circuit in the lamp, and by not using such an additional circuit, incompatibility with an intelligent controller in a constant current ballast is avoided. In the second operating mode, the LED lamp device relies on the SVM reduction circuit to reduce the SVM, and since there is no intelligent controller in the constant power ballast, the SVM reduction circuit can operate without problems. Switching between the first operating mode and the second operating mode can be achieved by deactivating the SVM reduction circuit when the ballast is a constant current ballast and activating the SVM reduction circuit when the ballast is a constant power ballast.

[0023] Constant current ballasts and constant wattage ballasts can be distinguished based on the current drawn from the ballast. As the name implies, constant current ballasts deliver a steady current that remains essentially constant regardless of whether the lamp is a fluorescent lamp or an LED lamp. In contrast, constant wattage ballasts are designed to deliver a (nominal) constant wattage to the lamp. When fluorescent lamps are replaced by LED lamp fixtures designed to run at a lower wattage, these ballasts tend to increase the current supplied to the LED lamp fixture to reach the design wattage. Therefore, by measuring the current drawn from the electronic ballast, a threshold can be applied to detect whether the ballast is a constant current ballast or a constant wattage ballast.

[0024] In this way, low SVM values ​​can be achieved regardless of whether the ballast is a constant current ballast or a constant power ballast.

[0025] In an embodiment, the SVM reduction circuit is adapted to reduce the voltage ripple across the plurality of LEDs such that the Stroboscopic Visibility Measure (SVM) level of the LED lamp device during operation is below 0.4. In this way, the LED lamp device will comply with current and future EU regulations.

[0026] For example, the energy storage device may include a capacitor having a capacitance value in the range of 68 μF-450 μF. This embodiment has the advantage of being simple in design.

[0027] In an embodiment, the SVM reduction circuit further comprises a Zener diode connected across the capacitor. The Zener diode may have a Zener breakdown voltage equal to or lower than the rated voltage of the capacitor. This makes it possible to maintain the voltage across the capacitor, thereby preventing the capacitor from bursting or failing.

[0028] In an embodiment, the SVM reduction circuit includes a switch (e.g., connected in series with a capacitor) adapted to connect the SVM reduction circuit to the plurality of LEDs when the current drawn from the electronic ballast exceeds a threshold value based on the output of the measurement and control circuit, and to disconnect the SVM reduction circuit from the plurality of LEDs when the current drawn from the electronic ballast does not exceed the threshold value. In this way, when the SVM reduction circuit is not needed (e.g., when the output of the measurement and control circuit indicates that the ballast is a constant current ballast), the SVM reduction circuit can be directly disconnected; when the SVM reduction circuit is needed (e.g., when the output of the measurement and control circuit indicates that the ballast is a constant power ballast), the SVM reduction circuit can be turned on. This makes it possible to use a single switch to activate / deactivate the SVM reduction circuit according to the present invention.

[0029] The switch may be any type of suitable switch, for example, an electromechanical switch such as a relay, or a semiconductor switch such as a transistor, MOSFET, etc. It should be noted that when referring to any switch described in this specification, the terms "open" and "closed" should also be understood to mean "off" and "on" or "disable" and "enable", respectively.

[0030] In an embodiment, the output of the measurement and control circuit indicates whether the ballast is a constant current ballast or a constant power ballast. For example, when the ballast is a constant current ballast, the output may be "0", and when the ballast is a constant power ballast, the output may be "1" (or vice versa). Alternatively, the output of the measurement and control circuit may represent a raw measurement value (e.g., a measured current value), in which case a threshold for activation / deactivation may be applied in the SVM reduction circuit. In both cases, the threshold for indicating whether the ballast is a constant current ballast or a constant power ballast may be, for example, set to any value in the range of 400-600 mA (rms).

[0031] The measurement and control circuit can measure the current drawn from the electronic ballast in a variety of different ways. For example, an impedance (e.g., a resistor) can be placed in series with the LED. This enables the voltage across the impedance to be measured, which corresponds to the current through the LED, which in turn represents the current drawn from the ballast. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Advantages of the present invention will become apparent from the following detailed description of exemplary non-limiting embodiments of the present invention, particularly when considered in conjunction with the accompanying drawings.

[0033] Figure 1 An embodiment of an LED lamp device 100 according to the present invention is shown.

[0034] Figure 2 An embodiment of an LED lamp device 100 is shown, in which the energy storage device 110 comprises a capacitor 110 a and a switch 110 b connected in series with the capacitor 110 a .

[0035] Figure 3 An embodiment of an LED lamp device 100 is shown, wherein the LED lamp device 100 further includes a ballast protection circuit 10 , which is similar to the SVM reduction circuit 110 and is activated or deactivated depending on whether the electronic ballast is a constant power ballast or a constant current ballast.

[0036] Figure 4 An embodiment of an LED lamp device 100 is shown, which has Figure 3 The LED lamp device 100 includes a ballast protection circuit 10 similar to that in the embodiment of the present invention, and the LED lamp device 100 further includes a switch mode power supply 30 and a filter circuit 20, and the LED lamp device 100 also has a third operation mode suitable for a magnetic ballast (or without a ballast). DETAILED DESCRIPTION

[0037] A more detailed description of exemplary embodiments of the invention follows.

[0038] Figure 1An embodiment of an LED lamp device 100 according to the present invention is shown. The LED lamp device 100 comprises a plurality of LEDs 101 , 102 , 103 , an SVM reduction circuit 110 and a measurement and control circuit 120 .

[0039] The SVM reduction circuit 110 includes an energy storage device (eg, a capacitor) connected across a plurality of LEDs. This circuit may include similar components as in a typical flicker reduction circuit, but the configuration may differ significantly to achieve a particular SVM value (eg, below 0.4).

[0040] The measurement and control circuit 120 is adapted to measure the current drawn from the electronic ballast and generate an output to the SVM reduction circuit 110. Based on this output, the measurement and control circuit 120 is configured to activate the SVM reduction circuit 120 when the current drawn from the electronic ballast exceeds a threshold value, and to deactivate the SVM reduction circuit when the current drawn from the electronic ballast does not exceed the threshold value.

[0041] When the ballast is a constant current ballast, the measurement and control circuit 120 uses its output to disable the SVM reduction circuit 100 (for example, by sending a disable signal to the SVM reduction circuit 110, or not sending any signal so that the SVM reduction circuit 100 remains in a default disabled state), and utilizes the existing circuits in the ballast to achieve an inherently low SVM value. Since the SVM reduction circuit is disabled, incompatibility with the intelligent controller in the constant current ballast is avoided.

[0042] When the ballast is a constant power ballast, the absence of an intelligent controller enables the SVM reduction circuit to be activated without causing any incompatibility issues. In this case, the measurement and control circuit 120 activates the SVM reduction circuit 110 using its output (e.g., by sending an activation signal to the SVM reduction circuit 110). The activation of the SVM reduction circuit 110 enables the desired SVM value (e.g., below 0.4) to be achieved. Tests conducted by the inventors on more than three hundred different ballasts have confirmed that for more than 98% of these ballasts, the LED lamp device 100 can be successfully lit while operating at an SVM value below 0.4 without compatibility issues.

[0043] It should be noted that although Figure 1 Three LEDs 101, 102, 103 are shown, but the LED lamp device 100 may include any number of LEDs. The LED lamp device may also include a plurality of connector pins 3 for receiving current from a lighting device, and one or more rectifier circuits 140 for rectifying the current received from the connector pins.

[0044] Figure 21 shows an embodiment of an LED lamp device 100, wherein the energy storage device 110 includes a capacitor 110a and a switch 110b connected in series with the capacitor 110a. The capacitor may have a capacitance value in the range of 68-450 μF. The LED lamp device 100 may include the above combined Figure 1 One or more elements of the description.

[0045] In this embodiment, the switch 110b is controlled by the output of the measurement and control circuit 120. According to the output, the switch 120 opens to disconnect the capacitor 110a from the LEDs 101, 102, 103 when the current drawn from the electronic ballast exceeds the threshold, and closes to connect the capacitor 110a to the LEDs 101, 102, 103 when the current drawn from the electronic ballast does not exceed the threshold. This makes it possible to disconnect (off) the SVM reduction circuit 110 when the output of the measurement and control circuit indicates that the ballast is a constant current ballast, and to connect (on) the SVM reduction circuit when the output of the measurement and control circuit indicates that the ballast is a constant power ballast. The switch can be any type of suitable switch, for example, an electromechanical switch such as a relay, or a semiconductor switch such as a transistor, MOSFET, etc.

[0046] The SVM reduction circuit 110 may optionally further include a Zener diode 110c connected across the capacitor. Preferably, the Zener diode has a Zener breakdown voltage equal to or lower than the rated voltage of the capacitor. This makes it possible to maintain the voltage across the capacitor, thereby preventing the capacitor from bursting or failing.

[0047] exist Figure 1 or Figure 2 The following additional measures may be implemented in the illustrated embodiment.

[0048] A threshold value may be applied in the measurement and control circuit 120 to detect whether the ballast is a constant current ballast or a constant power ballast. For example, when the ballast is a constant current ballast, its output may be "0", and when the ballast is a constant power ballast (or reverse), its output may be "1". Alternatively, the measurement and control circuit 120 may send an output when the ballast is a constant power ballast, and not send an output when the ballast is a constant current ballast, or vice versa. A threshold value may also be applied in the SVM reduction circuit 110, and the output of the measurement and control circuit 120 may represent a measured current value. In all of these cases, the threshold value may be set to any value within the range of 400-600mA (rms). The threshold value may also be set to other values ​​depending on the specific design of the LED lamp. A technician will understand how to set a specific threshold value for a given lamp design to distinguish between a constant current ballast and a constant power ballast through empirical testing.

[0049] The measurement and control circuit 120 can measure the current drawn from the electronic ballast in a variety of different ways. For example, an impedance (e.g., a resistor) can be placed in series with the LED. This enables the voltage across the impedance to be measured, which corresponds to the current through the LED, which in turn represents the current drawn from the ballast. In an exemplary embodiment, the measurement and control circuit 120 includes: an impedance or transimpedance circuit that converts the current drawn from the ballast to a first voltage level; and a comparator circuit (which may include an operational amplifier) ​​that is suitable for comparing the first voltage level with a reference voltage level to generate an output indicating whether a threshold value has been exceeded.

[0050] Figure 3 An embodiment of an LED lamp device 100 is shown, wherein the LED lamp device 100 further comprises a ballast protection circuit 10 as described in US Patent No. 10342079. In the embodiment shown, the ballast protection circuit 10 comprises an impedance 11, preferably having an inductive element such as an inductor.

[0051] When the measurement and control circuit 10 indicates that the ballast is a constant current ballast, the LED lamp device 100 operates in a first operation mode. In the first operation mode, as described above, the SVM reduction circuit 110 (eg, Figure 2 The SVM reduction circuit 110 is shown to be disabled. In addition, the impedance 11 in the ballast protection circuit is bypassed.

[0052] When the measurement and control circuit 10 indicates that the ballast is a constant power ballast, the LED lamp device switches to a second operating mode in which the SVM reduction circuit 110 is activated as described above. In addition, an impedance 11 in the ballast protection circuit 10 is connected in series with the LEDs 101, 102, 103. This provides an increased impedance in series with the LEDs to avoid excessive current that the constant power ballast attempts to supply through the LEDs.

[0053] The ballast protection circuit 10 acts as a variable impedance arranged in series with the LEDs 101, 102, 103. When the LED lamp device 100 draws current, the impedance of the ballast protection circuit 10 is low, but when the current exceeds a threshold, the impedance of the ballast protection circuit 10 increases to increase the impedance of the LED lamp device 100 at the output of the lighting device and the power supply ballast. This increased impedance reduces problems when operating the LED lamp with certain types of electronic ballasts (such as constant wattage ballasts), for example, by reducing the system power of such ballasts by approximately 15% by adding impedance in the circuit.

[0054] The ballast protection circuit 10 can be switched between at least two impedance values ​​to conduct current in at least a low impedance mode and a high impedance mode and optionally in other modes (e.g., two or more discrete operating modes). Alternatively, the ballast protection circuit 10 can include a variable impedance that can continuously change the effective impedance to conduct current at different impedance values.

[0055] The ballast protection circuit 10 is connected in series with the LEDs 101, 102, 103 so that a change in the impedance of the ballast protection circuit 10 will change the total impedance of the LED lamp device 100 across the output of the lighting device and the ballast. The ballast protection circuit 10 changes its impedance according to the current drawn by the LED lamp device 100. In this embodiment, when the current drawn from the ballast exceeds a predetermined threshold, indicating that the ballast is a constant power ballast, the ballast protection circuit 10 is arranged to automatically switch from a low impedance mode to a high impedance mode, so that the current flowing through the ballast protection circuit 10 and the LEDs 101, 102, 103 is reduced, so that the current drawn from the lighting device can be reduced, and thermal runaway and other adverse effects on the ballast can be avoided, and the life of the ballast can be increased.

[0056] In this way, even if the lighting device is equipped with a constant power ballast, the LED lamp device 100 that draws low power can be safely installed in a lighting device designed for a higher power fluorescent lamp (for example, a 28W LED lamp replaces a 58W fluorescent tube). The LED load impedance of the LED lamp device 100 is much lower than the load impedance of the fluorescent lamp. The constant power ballast will try to maintain its designed output power (for example, 58W). The output voltage across the ballast load (LED lamp device 100) will be low, and the ballast will respond by driving a higher output current to maintain a constant output power level. The ballast protection circuit 10 is designed to respond to higher ballast output current or voltage and automatically increase its impedance. The current flowing out of the ballast flows through the ballast protection circuit 10 and the LEDs 101, 102, 103, and the impedance change of the protection circuit 10 will affect the total impedance across the output end of the ballast. The increase in the total impedance of the LED lamp device 100 increases the voltage across the output end of the ballast and reduces the ballast output current to avoid damaging the ballast.

[0057] The LED lamp device 100 is suitable for replacing fluorescent lamps in lighting devices equipped with electronic ballasts. Optionally, the LED lamp device 100 may also include one or more measures described in the applicant's previous patents and patent applications (such as U.S. Patent No. 10342079, European Patent EP3449694 B1, and PCT Application WO2020 / 084087), so that the LED lamp device 100 is also suitable for replacing fluorescent lamps in lighting devices equipped with magnetic ballasts or without ballasts.

[0058] For example, the LED lamp device 100 may include a flicker reduction circuit as described in EP3449694 B1 to reduce flicker and / or SVM when the ballast is a magnetic ballast or when there is no ballast. The distinction between magnetic ballast / no ballast on the one hand and electronic ballast (constant current ballast and constant power ballast) on the other hand may be achieved by sensing the frequency of the power supplied to the LED lamp device, or various other mechanisms as described in the applicant's US Pat. No. 9441795. These mechanisms may be applied in the measurement and control circuit 120 or any other sensor circuit (not shown).

[0059] Figure 4 An embodiment of an LED lamp device 100 is shown that is suitable for operation with an electronic (constant current and constant power) ballast, a magnetic ballast, or no ballast, as described in US Pat. No. 10,342,079.

[0060] Similar to Figure 3 In the implementation method, Figure 4 The LED lamp device 100 includes a ballast protection circuit 10 (which may be Figure 3 10). In this embodiment, when the LED lamp device 100 detects that it receives power from a lighting device equipped with an electronic ballast, the ballast protection circuit 10 is configured to supply power to the LEDs 101, 102, 103. In addition, the LED lamp device 100 also includes a filter circuit 20 and a switch mode power supply 30 for supplying power to the LEDs 101, 102, 103 when the LED lamp device 100 detects that it receives power from a lighting device without a ballast or equipped with a magnetic ballast. A switching circuit 40 is also included for sensing the received power and switching various circuits according to the characteristics of the received power. The switching circuit 40 can be implemented as a centralized circuit for generating a plurality of switching signals, or as a plurality of separate circuits each generating a switching signal, wherein the plurality of signals together perform the function of the switching circuit 40. The switching circuit 40 can be implemented as one or more simple circuits formed by discrete circuit elements, or can be implemented as one or more integrated circuits or microcontrollers, etc. The integrated circuit or microcontroller may also be used to ensure that the switching signal does not switch the circuitry of the LED lamp device 100 into an unsafe or undesirable configuration.

[0061] In this embodiment, the LED lamp device 100 effectively comprises two parallel power supply circuits for powering the LEDs 101, 102, 103. The first power supply circuit is powered via the ballast protection circuit 10 for operation in a lighting device equipped with an electronic ballast. The second power supply circuit is powered via the filter circuit 20 and the switch mode power supply 30 for operation in a lighting device without a ballast or equipped with a magnetic ballast.

[0062] The switching circuit 40 detects the type of ballast (if any) supplying power to the LED lamp device 100, and switches the LED lamp device 100 between different operating modes according to the detection result. In an embodiment, the switching circuit 40 is designed to distinguish between power supplied directly from the main power supply or from a magnetic ballast on the one hand, and power supplied from an electronic ballast on the other hand.

[0063] In an embodiment, the switching circuit 40 senses the voltage supplied to the LED lamp device 100 to distinguish between an electronic ballast and a magnetic ballast or a direct mains supply. For a magnetic ballast or a direct mains supply, the voltage supplied to the LED lamp device 100 is essentially the mains voltage (e.g., 120 or 230 V AC). This is significantly higher than the typical output voltage of an electronic ballast, which is typically in the range of 40-80 V AC, depending on the number of LEDs 101, 102, 103 connected in series. This allows a simple, compact, and low-cost circuit to be applied in the switching circuit 40 to detect whether the supply voltage is above or below a threshold value (e.g., 100 V AC) to distinguish the type of ballast used.

[0064] In another embodiment, the switching circuit 40 senses the frequency of the voltage or current supplied to the LED lamp device 100 to distinguish between an electronic ballast and a magnetic ballast or a direct mains power supply. For a magnetic ballast or a direct mains power supply, the frequency of the AC voltage and current supplied to the LED lamp device 100 is substantially the mains frequency (e.g., 50 or 60 Hz). This is much lower than the typical output frequency of an electronic ballast, which is usually in the range of 20 to 200 kHz. Therefore, the switching circuit 40 can be designed to detect whether the supply frequency is above or below a threshold value to distinguish the type of ballast used.

[0065] Sensing of the supply voltage or frequency may be performed on the AC side of the rectifier, measuring the amplitude or frequency of the AC voltage received from the lighting device, or may be performed on the DC side of the rectifier, measuring the amplitude or ripple frequency of the rectified DC voltage supplied to the LED lamp device 100.

[0066] When the switching circuit 40 detects that the LED lamp device 100 receives power supplied from the electronic ballast, the switching circuit 40 switches to supplying power to the LEDs 101, 102, and 103 via the ballast protection circuit 10, and disconnects the second power supply circuit 51, and operates in the first operating mode or the second operating mode depending on whether the ballast is a constant current ballast or a constant power ballast (for example, as indicated by the measurement and control circuit 120).

[0067] In the first operating mode, the switch mode power supply 30 is not operating, the filter circuit 20 is disconnected, the ballast protection circuit 10 is connected, the impedance 11 is bypassed, and the SVM reduction circuit 110 is disabled. This mode is suitable for constant current ballasts.

[0068] In the second operating mode, the switch mode power supply 30 is not operating, the filter circuit 20 is disconnected, the ballast protection circuit 10 is connected, the impedance 11 is connected in series with the LED, and the SVM reduction circuit 110 is activated. This mode is suitable for constant power ballasts.

[0069] When the switching circuit 40 detects that the LED lamp device 100 receives power supplied from a magnetic ballast or a direct mains supply, the switching circuit 40 switches to supplying power to the LEDs 101, 102, 103 via the filtering circuit 20 and the switch mode power supply 30, and disconnects the ballast protection circuit. In this third operating mode, the ballast protection circuit 10 is disconnected, while the filtering circuit 20 is connected and the switch mode power supply 30 is enabled. Depending on the implementation, the SVM reduction circuit can be activated or deactivated.

[0070] The switch mode power supply 30 may be of conventional design for converting the rectified DC supply from the rectifier 140 to a switched DC output suitable for driving the LEDs 101 , 102 , 103 . The filter circuit 20 provides filtering for electromagnetic interference (EMI) generated by the switch mode power supply 30 .

[0071] The filter circuit 20 may also preferably include a surge protection circuit or device to protect against AC mains surges when the second power circuit 51 is connected for operation with a magnetic ballast or direct mains power. A metal oxide varistor (MOV) or similar circuit element may be used as a surge protection device, typically with a clamping voltage in the range of 275 V to 400 V. Such surge protection is not necessary when the first power circuit 50 is connected for operation with an electronic ballast, as the electronic ballast typically provides surge protection internally. In addition, electronic ballasts typically include a starting mechanism that generates a high starting voltage when turned on as a design feature for fast-start fluorescent lamps. When the LED lamp device 100 is installed in a lighting fixture equipped with an electronic ballast, repeated exposure to this initial high voltage each time the LED lamp device 100 is started may cause the surge protection device to fail prematurely. Therefore, when the switching circuit 40 detects that the LED lamp device 100 receives power supplied from the electronic ballast, the switching circuit 40 disconnects the filter circuit 20 and disconnects the surge protection circuit or device.

[0072] Those skilled in the art will understand that the embodiments described herein all relate to an LED lamp assembly having a method for adjusting lamp power, and features associated with one embodiment may be used or combined with features of other embodiments. Although the principles of the present invention have been described above in conjunction with specific embodiments, it should be understood that these descriptions are intended only as examples and not as limitations on the scope of protection, which is defined by the appended claims.

Claims

1. An LED lamp device (100) for replacing a fluorescent lamp in a lighting device equipped with an electronic ballast, the LED lamp device (100) comprising: - a plurality of LEDs (101, 102, 103); - an SVM reduction circuit (110) comprising an energy storage device (110a) connected across the plurality of LEDs (101, 102, 103); and - a measurement and control circuit (120) adapted to measure the current drawn from the electronic ballast and to generate an output to the SVM reduction circuit (110); Wherein, based on the output, the measurement and control circuit (120) is configured to deactivate the SVM reduction circuit (110) when the current drawn from the electronic ballast does not exceed a threshold value, and activate the SVM reduction circuit (110) when the current drawn from the electronic ballast exceeds a threshold value, so that: - when the ballast is a constant current ballast, the LED lamp device (100) operates in a first operation mode, in which the SVM reduction circuit (110) is deactivated; and - When the ballast is a constant power ballast, the LED lamp device (100) operates in a second operation mode in which the SVM reduction circuit (110) is activated.

2. The LED lamp device (100) according to claim 1, wherein: The SVM reduction circuit (110) is adapted to reduce voltage ripple across the plurality of LEDs (101, 102, 103) such that a Stroboscopic Visibility Measurement (SVM) level of the LED lamp device (100) during operation is below 0.

4.

3. The LED lamp device (100) according to claim 1 or 2, wherein: The energy storage device includes a capacitor with a capacitance value in the range of 68-450 μF.

4. The LED lamp device (100) according to claim 3, wherein: The SVM reduction circuit further includes a Zener diode (110c) connected to both ends of the capacitor, wherein the Zener diode has a Zener breakdown voltage equal to or lower than a rated voltage of the capacitor.

5. The LED lamp device (100) according to any one of the preceding claims, wherein: The SVM reduction circuit (110) comprises a switch (110b) adapted to: based on the output of the measurement and control circuit (120), connect the SVM reduction circuit (110) to the plurality of LEDs when the current drawn from the electronic ballast exceeds a threshold value, and disconnect the SVM reduction circuit (110) from the plurality of LEDs when the current drawn from the electronic ballast does not exceed the threshold value.

6. The LED lamp device (100) according to claim 5, wherein: The switch (110b) comprises a semiconductor switch.

7. The LED lamp device (100) according to any one of the preceding claims, wherein: The output of the measurement and control circuit (120) indicates whether the ballast is a constant current electronic ballast or a constant power electronic ballast.

8. The LED lamp device (100) according to any one of the preceding claims, wherein: The threshold is in the range of 400 - 600 mA (rms) and indicates whether the ballast is a constant current electronic ballast or a constant power electronic ballast.

9. The LED lamp device (100) according to any one of the preceding claims, further comprising: A ballast protection circuit (10) comprises an impedance (11), such as an inductor, wherein the impedance is bypassed in the first operation mode and connected in series with the plurality of LEDs in the second operation mode.

10. The LED lamp device (100) according to claim 9, wherein: The ballast protection circuit (10) comprises a switch (12) connected in parallel with the impedance, wherein the switch is closed in the first operation mode and is open in the second operation mode.

11. The LED lamp device (100) according to any one of the preceding claims, wherein: The LED lamp device further comprises: A ballast protection circuit (10) comprising an impedance (11); Filter circuit (20); A switch mode power supply (30) for driving one or more LEDs (101, 102, 103); one or more sensing circuits for generating at least one output based on power received from the lighting device indicating whether the power is provided via a magnetic ballast, via an electronic ballast operating as a constant current ballast, via an electronic ballast operating as a constant power ballast, or not provided via a ballast; and a plurality of switches (40, 12, 110b) configured to define a plurality of operating modes of the LED lamp device (100) and to switch between the plurality of operating modes according to at least one output from the one or more sensing circuits, wherein the plurality of operating modes include the first operating mode and the second operating mode, and also include a third operating mode, wherein: - in the first operating mode, the switch mode power supply (30) is not operating, the filter circuit (20) is disconnected, the ballast protection circuit (10) is connected, the impedance (11) is bypassed, and the SVM reduction circuit is deactivated; - in the second operating mode, the switch mode power supply (30) is not operating, the filter circuit (20) is disconnected, the ballast protection circuit (10) is connected, the impedance (11) is connected in series with the plurality of LEDs, and the SVM reduction circuit is activated; and - In the third operating mode, the switch mode power supply (30) operates at an operating frequency, the filter circuit (20) is connected to filter noise generated by the switch mode power supply, and the ballast protection circuit (10) is disconnected.

12. The LED lamp device (100) according to any one of the preceding claims, wherein: The LED lamp device (100) further comprises: A ballast protection circuit (10) switchable between a low impedance mode and a high impedance mode; A filter circuit (20); and A switch mode power supply (30) for driving one or more LEDs (101, 102, 103), The LED lamp device (100) is configured to: when the LED lamp device (100) detects that the electric energy received from the lighting device is provided via a constant current ballast, the SVM reduction circuit (110) is disabled and power is supplied to one or more LEDs (101, 102, 103) via the ballast protection circuit (10) operating in the low impedance mode, The LED lamp device (100) is configured to: when the LED lamp device (100) detects that the electric energy received from the lighting device is provided via a constant power ballast, power is supplied to one or more LEDs via the ballast protection circuit (10) operating in the high impedance mode while the SVM reduction circuit (110) is activated, and The LED lamp device (100) is configured to supply power to one or more LEDs (101, 102, 103) via the filter circuit (20) and the switch mode power supply (30) when the LED lamp device (100) detects that the electric energy received from the lighting device is provided via a magnetic ballast or is not provided via a ballast.

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