Power source module for LED lamp

This application is a continuation application of U.S. application Ser. No. 14/699,138, filed Apr. 29, 2015, the contents of which are incorporated herein by reference in their entirety. The U.S. application Ser. No. 14/699,138 claims the benefit of the filing date of Chinese Patent Application No. 201420602526.2, filed Oct. 17, 2014, entitled “POWER SOURCE MODULE FOR LED LAMP,” and the contents of which are hereby incorporated by reference in their entirety.

The present disclosure relates to a power source module for a light emitting diode (LED) lamp, and more particularly, the present disclosure relates to a power source module for enabling the LED lamp installed on the traditional fluorescent lamp base.

Fluorescent lamps have been used widely in the world for illumination. The traditional fluorescent lamp is detachably installed on a fluorescent lamp base to receive the power from the power source in the base to emit light. According to the principle of luminosity of the traditional fluorescent lamp, the fluorescent lamp base has to provide a starter and a ballast to drive the traditional fluorescent lamp. The starter is used for heating filaments in the fluorescent lamp and raising a voltage between the two terminals of the fluorescent lamp, so as to ignite the fluorescent lamp to light. The traditional fluorescent lamp has a negative incremental impedance characteristic, so that it needs the ballast to limit the amount of the current for preventing the fluorescent lamp from damage.

The traditional fluorescent lamp is filled with Argon, Neon, Krypton at low atmospheric pressure, and a bit of mercury vapor which is harmful. The traditional fluorescent lamp also has the disadvantages of high power consumption and high heat generation. Compared to the traditional fluorescent lamp, the LED lamp has the advantages of absence of mercury pollution, more power saving, and longer life. Therefore, the LED lamps are adopted more widely in the world recently to replace the traditional fluorescent lamps.

To replace the traditional fluorescent lamp by the LED lamp, the original circuit included in the fluorescent lamp base might need to be modified to adapt the LED lamp. There are two types of fluorescent lamp bases: one adopts an independent starter and an inductance as the ballast; the other adopts an electrical ballast including the starter therein. The inductance opposes the change in current and so the inductance ballast would attempt to keep the current of the LED lamp in a substantially fixed current. The starter and the electrical ballast generate a gaseous electric discharge in the fluorescent lamp by raising the voltage, and so it would cause the LED lamp to burn away. For the first type of the fluorescent lamp base, the LED lamp can be installed on the base directly and operates normally by taking the starter away and retaining the inductance ballast, and the starter in this type of fluorescent lamp base can be easily taken away by the user. On the contrary, the electrical ballast needs to be removed away by the user, and further the circuit in the fluorescent lamp base must be modified correspondingly for the LED lamp.

The modification to the electric ballast type fluorescent lamp base is complicated to the user, even to the professional. Also, it needs manpower and material resources to make the modification. The inconvenience of the modification to the electric ballast keeps the users from replacing the traditional fluorescent lamp with the LED lamp.

Accordingly, the present disclosure and its embodiments are herein provided to address the above issues.

One object of the present disclosure is to provide a power source module for an LED lamp for use in a fluorescent lamp base including a ballast.

According to an embodiment of the invention, the power source module includes a filament-simulating circuit, a first rectifier, and a filter. The filament-simulating circuit is electrically connected to a first and a second bi-pin terminals of the LED lamp. Each of the first and the second bi-pin terminals has a current flowing from one pin to the other pin via the filament-simulating circuit during a pre-heat process executed by the ballast of the fluorescent lamp base. The first rectifier is electrically connected to the first bi-pin terminal for rectifying the current from the first bi-pin terminal. The filter is electrically connected between the first rectifier and at least one LED of the LED lamp for smoothing the current from the first rectifier and then outputting the current to the LED.

The power source module prevents the LED lamp from burning away by a high voltage, so as to enable the LED lamp installed on the traditional fluorescent lamp base to operate normally without modifying the circuit in the base.

Another object of the present invention is to provide a power source module for an LED lamp having a current limiting circuit to protect the LED lamp.

According to another embodiment, the power source module includes a current limiting circuit, a first rectifier, and a filter. The current limiting circuit is electrically connected to a first terminal of the LED lamp for limiting a circuit from the terminal. The first rectifier is electrically connected to the current limiting circuit, and the filter is electrically connected to the first rectifier, so as to rectifying and smoothing the current.

Another object of the present invention is to provide a power source module for an LED lamp having a discharge circuit to prevent the LED lamp from flicker when turning off the LED lamp.

According to another embodiment, the power source module includes a rectifier, a filter, and a discharge circuit. The rectifier electrically connected to the terminals of the LED lamp for receiving a current, the filter is electrically connected between the rectifier and at least one LED of the LED lamp to storing energy for smoothing the current, and the discharging circuit is electrically connected to the filter in parallel for discharging the energy in the filter.

On the advantages and the spirit of the invention, it can be understood further by the following invention descriptions and attached drawings.

FIG. 1 is a function block diagram illustrating a power source module for an LED lamp according to an embodiment of the invention.

FIG. 2 is a schematic diagram illustrating a power source module for an LED lamp according to another embodiment of the invention.

FIG. 3 is a schematic diagram illustrating a power source module for an LED lamp according to another embodiment of the invention.

Please refer to FIG. 1 . FIG. 1 is a function block diagram illustrating a power source module 1 for an LED lamp according to an embodiment of the invention. The power source module 1 may be configured inside a casing of the LED lamp to connect an LED module 2 of the LED lamp to terminals of the LED lamp. The LED module includes at least one LED.

As shown in FIG. 1 , the power source module 1 includes a filament-simulating unit 10 , a current limiting circuit 12 , a rectifier 14 , and a filter 16 . The filament-simulating unit 10 is electrically connected to the terminals of the LED lamp. The terminals of the LED lamp includes a first bi-pin terminal T 1 and a second bi-pin terminal T 2 , and each of the first and the second bin-pin terminals T 1 , T 2 further include two pins. These pins of the first and the second bin-pin terminals T 1 , T 2 are configured to be detachably installed on the traditional fluorescent lamp base for receiving a current therefrom. The filament-simulating unit 10 also includes a first filament-simulating circuit 100 and a second filament-simulating circuit 102 connected to the pins of the first bi-pin terminal T 1 and the second bi-pin terminal T 2 , and therefore, the filament-simulating unit 10 may also be referred to as a filament-simulating circuit 10 . The power source module 1 may also be described as a power source circuit, or a power supply circuit.

The first filament-simulating circuit 100 and the second filament-simulating circuit 102 are able to receive current(s) via the bi-pin terminals T 1 , T 2 and power source ends of the fluorescent lamp base from an external power source. During a pre-heat process executed by the ballast of the fluorescent lamp base, a current flows from one pin to the other pin of the first bi-pin terminal T 1 via the first filament-simulating circuit 100 , and similarly a current from one pin to the other pin of the second bi-pin terminal T 2 via the second filament-simulating circuit 102 respectively. The current limiting circuit 12 is electrically connected to the first bi-pin terminals T 1 , and used for limiting the current from the first bi-pin terminal T 1 to be in a suitable range for driving the LED module 2 . The rectifier 14 is electrically connected between the current limiting circuit 12 and the second filament-simulating circuit 102 . The rectifier 14 is used for rectifying the current from the bi-pin terminals T 1 , T 2 . The current inputted from the external power source is an alternating current, and the rectifier 14 rectifies the alternating current to be a direct current. The filter 16 is electrically connected to the rectifier 14 for filtering the rectified current and outputting the filtered current to the LED module 2 .

The ballast may execute a pre-heat process to the filaments of the traditional fluorescent lamp for pre-heating the filaments. The filament-simulating unit 10 can simulate a filament of the traditional fluorescent lamp, so as to prevent the ballast from erroneously judging that the filaments are open-circuited or short-circuited during the pre-heating process of the ballast.

Please refer to FIG. 2 . FIG. 2 is a schematic diagram illustrating a power source module 3 for an LED lamp according to another embodiment of the invention.

As shown in FIG. 2 , the power source module 3 includes a filament-simulating unit 30 , a current limiting circuit 32 , a rectifier 34 , and a filter 36 electrically connected between the LED module 2 and two bi-pin terminals T 1 and T 2 . It should be noted that although FIG. 2 only shows one LED of the LED module 2 , the LED module 2 may include more than one LED connected in parallel and/or in series in another embodiment. The filament-simulating unit 30 includes a first filament-simulating circuit 300 connected to the first bi-pin terminal T 1 and a second filament-simulating circuit 302 connected to the second bi-pin terminal T 2 .

The first filament-simulating circuit 300 includes a pair of resistors, e.g., resistances R 1 , R 2 and a pair of capacitors, e.g., capacitances C 1 , C 2 . The term “capacitance(s)” described herein may also be referred to as “capacitor(s)” and the term “resistance(s)” described herein may also be referred to as “resistor(s).” The resistances R 1 and R 2 are connected in series, and the capacitances C 1 and C 2 are connected in series. The pair of resistances and the pair of capacitances are connected in parallel between the pins of the first bi-pin terminal Ti. The connection point between resistances R 1 , R 2 is electrically connected to the connection point between capacitances C 1 , C 2 . Thereby, when one of the resistances R 1 , R 2 and the capacitances C 1 , C 2 is open circuited, the first filament-simulating circuit 300 still works.

Similarly, the second filament-simulating circuit 302 includes a pair of resistors, e.g., resistances R 3 , R 4 and a pair of capacitors, e.g., capacitances C 3 , C 4 . The connecting relations of R 3 , R 4 , T 3 , T 4 , and the pins of the second bi-pin terminal T 2 are similar to those of the first filament-simulating circuit 300 and the first bi-pin terminal T 1 , as shown in FIG. 2 .

The values of the resistances R 1 , R 2 , R 3 , R 4 and the capacitances C 1 , C 2 , C 3 , C 4 could be matched in a reasonable range, for example, when the ballast provides a high frequency signal into the power source module 3 , the impedance of the first pair of resistances R 1 , R 2 could be ten times more than that of the first pair of capacitances C 1 , C 2 , and an impedance of the second pair of resistances R 3 , R 4 could be ten times more than that of the second pair of capacitances. In this embodiment, the value of the resistances could be 100 Ka and the value of the capacitances could be 220 nF. The resistances R 1 , R 2 , R 3 , R 4 and the capacitances C 1 , C 2 , C 3 , C 4 could be electrically connected to the ballast in the traditional fluorescent lamp base via the first bi-pin terminal T 1 and the second bi-pin terminal T 2 , to simulate the filaments during the pre-heating process of the ballast. After the pre-heating process, the ballast enters a normal operation state, and outputs an alternating current with a high frequency, e.g., 45 KHz, to the current limiting circuit 32 .

The current limiting circuit 32 includes at least one capacitor, and in this embodiment, capacitances C 5 and C 6 . The capacitances C 5 and C 6 may be film capacitances to increase the reliability of the power source module 3 . One end of the capacitance C 5 is connected to one of the pins of the first bi-pin terminal T 1 . One end of the capacitance C 6 is connected to the other of the pins of the first bi-pin terminal T 1 . The other ends of the capacitance C 5 and the capacitance C 6 are connected together, and connected to the rectifier 34 . The values of the capacitances C 5 and C 6 can be matched to limit the value the current in a reasonable range when the ballast provides a high voltage to the LED module 2 . The reasonable range is defined to the current range which drives the LED module 2 to operate normally, so that the reasonable range would vary with different types of LED or LED array. In practice, the reasonable range could be under 217 mA. The capacitances C 5 and C 6 are connected to different pins of the first bi-pin terminal T 1 , so that the value of the current from any one of the pins is assured to be limited in the reasonable range.

Please refer to FIG. 3 . FIG. 3 is a schematic diagram illustrating a power source module 3 for an LED lamp according to another embodiment of the invention. As shown in FIG. 3 , the difference between this embodiment and the last embodiment is that the current limiting circuit 32 further includes the third capacitance C 7 connected between the capacitances C 5 and C 6 and the rectifier 34 , so as to ensure the value of the current in the reasonable range even if one of the capacitances C 5 and C 6 is damaged. In a preferred embodiment, the values of the capacitances C 5 , C 6 , C 7 are in the range of 0.47 nF to 12 nF, and in this embodiment, the values of the capacitances C 5 , C 6 are 3.3 nF, and the value of the capacitance C 7 is 8.2 nF.

The rectifier 34 includes a first rectifier 340 and a second rectifier 342 electrically connected to the current limiting circuit 32 and the second filament-simulating circuit 302 respectively for receiving and rectifying the current from the current limiting circuit 32 . Furthermore, the rectifier 34 is connected to the LED module 2 for outputting the rectified current thereto. The rectifier 34 includes six diodes D 1 , D 2 , D 3 , D 4 , D 5 , and D 6 , wherein the first rectifier 340 includes diodes D 1 , D 2 electrically connected in series and the second rectifier 342 includes diodes D 3 , D 4 , D 5 , and D 6 electrically connected to each other to form a bridge rectifier. In the embodiment shown in FIG. 2 , the first diode D 1 has an anode connected to the junction point of the capacitances C 5 and C 6 and a cathode thereof connected to the anode of the LED module 2 . In the embodiment shown in FIG. 3 , the first diode D 1 has an anode connected to the third capacitance C 7 and a cathode thereof connected to the anode of the LED module 2 . The second diode D 2 has an anode connected to the cathode of the LED module 2 and a cathode thereof connected to the third capacitance C 7 . A current may flow from the LED module 2 to one pin of the first bi-pin terminal T 1 through the diode D 2 and the current limiting circuit 32 , or from one pin of the first bi-pin terminal T 1 to the LED module 2 through the diode D 1 and the current limiting circuit 32 . The third diode D 3 has an anode connecting to one of the pins of the second bi-pin terminal T 2 and a cathode connected to the anode of the LED module 2 . The fourth diode D 4 has an anode connected to the cathode of the LED module 2 and a cathode connected to the anode of the third diode D 3 . The fifth diode D 5 has an anode connected to the other of the pins of the second bi-pin terminal T 2 and a cathode connected to the anode of the LED module 2 . The sixth diode D 6 has an anode connected to the cathode of the LED module 2 and a cathode connected to the anode of the fifth diode D 5 which is connected to the other of the pins of the second bi-pin terminal T 2 .

The diodes of the rectifier 34 make a full-wave rectification to the current limited by the current limiting circuit 32 , to output a rectified, direct current with a double frequency. For example, the current from the current limiting circuit 32 was an alternating current with frequency of 45 KHz, and the rectified current output by the rectifier 34 is a direct current with frequency of 90 KHz. The rating current/voltage values of the diodes of the rectifier 34 are 1 A/1000V, in this embodiment.

The filter 36 includes a filtering capacitance C 8 connected to the rectifier 34 and the LED module 2 in parallel, as shown in FIGS. 2 and 3 . The filtering capacitance C 8 is used for storing energy from the rectifier 34 to filter and smooth the rectified current from the rectifier 34 , and then outputting the filtered current to drive the LED module 2 . The value of the filtering capacitance C 8 is 680 nF, in this embodiment.

In this embodiment, the power source module 3 further includes a pair of discharging resistances R 5 and R 6 connected in series. The discharging resistance pair is connected to the filter 36 and the LED module 2 in parallel. The discharging resistances R 5 and R 6 can discharge the energy stored in the filtering capacitance C 8 rapidly to prevent the LED lamp from flicker when turning off the power inputted to the power source module.

As described above, the power source module for the LED lamp simulates the filaments to prevent the ballast from stopping supplying power due to the error judgement during the pre-heating process. The current provided by the external power source after the pre-heating process can be limited, rectified, and filtered by the power source module to a suitable direct current to drive the LED, and the energy can be discharge rapidly after turning power off. Therefore, the power source module enables the LED lamp installed on the traditional fluorescent lamp base to operate normally without modifying the circuit in the base.

Although the present invention has been illustrated and described with reference to the preferred embodiment thereof, it should be understood that it is in no way limited to the details of such embodiment but is capable of numerous modifications within the scope of the appended claims.