UNIVERSAL LED TUBE AND POWER SYSTEM OF THE UNIVERSAL LED TUBE

Abstract

 A universal LED tube and a power system of the universal LED tube are provided. The universal LED tube utilizes an external electric power being selectably a low frequency electric power to emit light. The universal LED tube comprises a LED unit (101) and a LED driving circuit. The LED driving circuit comprises a power converter unit (102, 102') and a power filter unit (104, 104'). The power converter unit (102, 102') provides a DC power to the LED unit (101) according to the low frequency electric power. The power filter unit (104, 104') is electrically coupled to a first side portion (1a) and the power converter unit (102, 102'). The low frequency electric power passes from the first side portion (1a) through the power filter unit (104, 104') to the power converter unit (102, 102'), for driving the LED unit (101). The universal LED tube can be applied to an existing tube holder of a conventional fluorescent tube, for avoiding cost of wire modifications.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The instant disclosure relates to an LED tube; in particular, to a universal LED tube and a power system of the universal LED tube.

2. Description of Related Art

[0002] The existed conventional fluorescent tube in the market has an issue of more power consumption compared to the LED tube. Thus, there is a tendency to gradually replace the conventional fluorescent tube by the LED tube. However, the driving manner of the conventional fluorescent tube is different from that of the LED tube. There are many kinds of manner for enabling the conventional fluorescent tube to emit light (or start). And, different start circuits exist in different country or area. The conventional fluorescent tube usually uses a ballast (or stabilizer), such like a magnetic ballast or an electronic ballast, which is installed in the tube holder to achieve the purpose of enabling to start to emit light and stable operation.

[0003] Considering a verity kinds of start circuits used for the conventional fluorescent tube, it may be required to modify or replace the wiring of the tube holder for complying with the driving manner of the LED tube when replacing the conventional fluorescent tube by the LED tube. As a result, it may cause the inconvenience of using the LED tube. Such that, it creates an obstacle for promoting use of the power saving LED tube.

SUMMARY OF THE INVENTION

[0004] The object of the instant disclosure is to provide a universal LED tube and a power system of the universal LED tube, which provide path planning for the current of different frequency, in order to provide different current paths.

[0005] In order to achieve the aforementioned objects, according to an embodiment of the instant disclosure, a universal LED tube is provided. The universal LED tube utilizes an external electric power to emit light. The external electric power is selectably a low frequency electric power. The universal LED tube has a first side portion and a second side portion. The universal LED tube further comprises a LED unit and a LED driving circuit. The LED driving circuit is coupled to the LED unit, the first side portion and the second side portion, so as to drive the LED unit lighting by the external electric power. The LED driving circuit comprises a power converter unit and a power filter unit. The power converter unit is electrically coupled to the LED unit. The power converter unit provides a DC power to the LED unit according to the low frequency electric power. The power filter unit is electrically coupled to the first side portion and electrically coupled to the power converter unit, wherein the low frequency electric power passes from the first side portion through the power filter unit to the power converter unit, so as to drive the LED unit to emit light according to the low frequency electric power.

[0006] In order to achieve the aforementioned objects, according to an embodiment of the instant disclosure, a power system is provided. The power system comprises a tube holder and the aforementioned universal LED tube. The tube holder provides the external electric power which is selectably a low frequency electric power or a high frequency electric power.. The universal LED tube is connected to the tube holder.

[0007] In summary, the provided universal LED tube and the power system of the universal LED tube can realize applications for replacing the conventional fluorescent tube operating with magnetic ballast or electronic ballast, without modifying the wiring of the tube holder. Accordingly, the wire modification cost of installing the LED tube can be avoided (or decreased).

[0008] In order to further the understanding regarding the instant disclosure, the following embodiments are provided along with illustrations to facilitate the disclosure of the instant disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] 

Fig. 1A shows a block diagram of a LED driving circuit of a universal LED tube according to an embodiment of the instant disclosure;

Fig. 1B shows a schematic diagram of the appearance of a universal LED tube according to an embodiment of the instant disclosure;

Fig. 2A shows a circuit diagram of a LED driving circuit of a universal LED tube according to an embodiment of the instant disclosure;

Fig. 2B shows the current conduction paths of the circuit of Fig. 2A under low frequency operation;

Fig. 2C shows the current conduction paths of the circuit of Fig. 2A under high frequency operation;

Fig. 3A shows a circuit diagram of an LED driving circuit of a universal LED tube according to another embodiment of the instant disclosure;

Fig. 3B shows the positive half-cycle current conduction path of the circuit of Fig. 3A under low frequency operation;

Fig. 3C shows the negative half-cycle current conduction path of the circuit of Fig. 3A under high frequency operation;

Fig. 4 shows a circuit diagram of an LED driving circuit of a universal LED tube according to another embodiment of the instant disclosure;

Fig. 5 shows a circuit diagram of an LED driving circuit of a universal LED tube according to another embodiment of the instant disclosure;

Fig. 6 shows a simplified circuit of a self-excited high frequency electronic ballast of a conventional fluorescent tube;

Fig. 7A shows a circuit diagram of a universal LED tube applied to the circuit architecture of Fig. 6 according to another embodiment of the instant disclosure;

Fig. 7B shows a circuit diagram of a universal LED tube applied to the circuit architecture of Fig. 6 according to another embodiment of the instant disclosure;

Fig. 7C shows a circuit diagram of a universal LED tube applied to the circuit architecture of Fig. 6 according to another embodiment of the instant disclosure;

Fig. 7D shows a circuit diagram of a universal LED tube applied to the circuit architecture of Fig. 6 according to another embodiment of the instant disclosure;

Fig. 8 shows a circuit diagram of a conventional fluorescent tube using a magnetic ballast;

Fig. 9 shows a circuit diagram of a conventional fluorescent tube using an isolated external-exciting electronic ballast;

Fig. 10 shows a schematic diagram of a universal LED tube applied to the architecture of a single-ended power feeding according to another embodiment of the instant disclosure; and

Fig. 11 shows a schematic diagram of a universal LED tube applied to the architecture without a starter according to another embodiment of the instant disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The aforementioned illustrations and following detailed descriptions are exemplary for the purpose of further explaining the scope of the instant disclosure. Other objectives and advantages related to the instant disclosure will be illustrated in the subsequent descriptions and appended drawings.

[An embodiment of a universal LED tube and a power system of the universal LED tube]

[0011] Please refer to Fig. 1A in conjunction with Fig. 1B. Fig. 1A shows a block diagram of an LED driving circuit of a universal LED tube according to an embodiment of the instant disclosure. Fig. 1B shows a schematic diagram of the appearance of a universal LED tube according to an embodiment of the instant disclosure. The power supply system of the universal LED tube comprises a tube holder (not shown in the figures) and a universal LED tube 1. The tube holder can be the conventional fluorescent tube holder, for providing external electric power. The universal LED tube 1 utilizes the external electric power to emit light. The universal LED tube can be a lamp designated as T8 in lamp format, but the instant disclosure is not so restricted. The external electric power cab be selectably either a low frequency electric power or a high frequency electric power. The low frequency electric power in this embodiment can be an electric power with frequency of tens of Hertz, such as 50Hz or 60Hz AC power of household electricity, but the instant disclosure is not so restricted. The low frequency electric power such as 50Hz or 60Hz AC power is usually applied to the application of the conventional fluorescent tube holder with magnetic ballast. The high frequency electric power can be an AC power with frequency ranges from 20kHz to 200kHz, such as tens of kHz or 150kHz. High frequency electric power is usually used for applications of the conventional fluorescent tube holder with electronic ballast. However, the instant disclosure is not so restricted.

[0012] As shown in Fig. 1B, the universal LED tube 1 has a first side portion 1a and a second side portion 1b. The first side portion 1a has a first pin CON1 and a second pin CON2. The second side portion 1b has a third pin CON3 and a fourth pin CON4. An LED driving circuit 10 and an LED unit 101 are disposed in the universal LED tube 1. The LED driving circuit 10 comprises a power converter unit 102, a rectifier unit 103 and a power filter unit 104.

[0013] The power converter unit 102 is electrically coupled to the LED unit 104, for providing a DC power to the LED unit 101 according to the low frequency electric power. The rectifier unit 103 is electrically coupled to the LED unit 101, the third pin CON3 and the fourth pin CON4, for rectifying the high frequency electric power, and providing the rectified high frequency electric power to the LED unit 101. The power filter unit 104 is electrically coupled to the first pin CON1, the second pin CON2, the power converter unit 102 and the rectifier unit 103. The low frequency electric power passes from the first pin CON1 and the second pin CON2 through the power filter unit 104 to the power converter unit 102, and the rectifier unit 103 conducts the high frequency electric power through the power filter unit 104.

[0014] A detailed circuit of the LED driving circuit 10 of this embodiment is described in the following. Please refer to Fig. 2A, the power filter unit 104 comprises a filtering capacitor C1 and a filtering capacitor C2. The filtering capacitor C1 is electrically coupled between the first pin CON1 and the second pin CON2, for isolating the high frequency electric power, and conducting the low frequency electric power. The filtering capacitor C2 is electrically coupled between the first pin CON1 and the rectifier unit 103, for isolating the low frequency electric power, and conducting the high frequency electric power. In addition, the third pin CON3 and the fourth pin CON4 are commonly connected.

[0015] The power converter unit 102 comprises a filter 1021, a rectifier 1022 and a DC converter 1023. The filter 1021 is electrically coupled to the first pin CON1 and the second pin CON2 through the power filter unit 104. The rectifier 1022 is electrically coupled to the filter 1021. The DC converter 1023 is electrically coupled between the rectifier 1022 and the LED unit 101, for providing the DC power to the LED unit 101 according to the rectified low frequency electric power. The DC converter 1023 shown in Fig. 2A is for example a buck-boost converter, but the instant disclosure is not restricted thereto. In other embodiments hereinafter, the DC converter1023 can be a buck converter for example. An artisan of ordinary skill in the art will appreciate the operation mechanism of the DC converter 1023, thus there is no need to go into detail.

[0016] As shown in Fig. 2A, for the first pin CON1 and the second pin CON2, the first filtering capacitor C1 is connected with the power converter unit 102 in parallel. The power filter unit 104 provides a low frequency current path, such that the power converter unit 102 can obtain the low frequency electric power. The rectifier unit 103 is electrically coupled to the first pin CON1 through the second filtering capacitor C2, such that the power filter unit 104 and the rectifier unit 103 can establish a high frequency current path for passing the high frequency electric power. For low frequency electric power, the impedances of the first filtering capacitor C1 and the second filtering capacitor C2 are very large, the current flowing through the first filtering capacitor C1 is very small, and the current flowing through the high frequency current path can be ignored (the current flowing through the second filtering capacitor C2 is very small), such that the current of the low frequency electric power mainly flows into the power converter unit 102. For high frequency electric power, the impedances of the first filtering capacitor C1 and the second filtering power C2 are very small, such that the high frequency electric power does not flow into the power converter unit 102, and the current of the high frequency electric power mainly passes the rectifier unit 103. By the design of impedance, the high frequency electric power can be isolated from the low frequency electric power. Also, the current path of the high frequency electric power is different from the current path of the low frequency electric power.

[0017] The LED unit 101 can be an LED string or a plurality of LED strings, but the instant disclosure is not so restricted. The LED unit 101 has a positive terminal 101a and a negative terminal 101b. The conducting current of the LED unit 101 flows from the positive terminal 101a of the LED unit 101 to the negative terminal 101b of the LED unit 101.

[0018] The rectifier unit 103 comprises a diode D1 and a diode D2. The diode D1 and the diode D2 provide bi-directional rectification for the high frequency electric power. The anode of the diode D1 is electrically coupled to the first pin CON1 through the second filtering capacitor C2. The cathode of the diode D1 is electrically coupled to the positive terminal 101a of the LED unit 101. The cathode of the diode D2 is electrically coupled to the first pin CON1 through the second filtering capacitor C2. The anode of the diode D2 is electrically coupled to the negative terminal 101b of the LED unit 101.

[0019] Furthermore, in this embodiment, the rectifier unit 103 further comprises a diode D3 and a diode D4. The diode D3 and the diode D4 also provide bi-directional rectification. The anode of the diode D3 is electrically coupled to the negative terminal 101b of the LED unit 101. The cathode of the diode D3 is electrically coupled to the third pin CON3 and the fourth pin CON4. The cathode of the diode D4 is electrically coupled to the positive terminal 101 a of the LED unit 101. The anode of the diode D4 is electrically coupled to the third pin CON3 and the fourth pin CON4. Additionally, a safe capacitor CS can be used for avoiding electricity leakage of the third pin CON3 and the fourth pin CON4 when only the first pin CON1 and the second pin CON2 of the tube are connected to the electric power during the installation of the tube. That is, considering risk of electric shock for the person assembling the tube when the third pin CON3 and the fourth pin CON4 are exposed and not connected to the tube holder, the safe capacitor CS can improve the safety during assembling of the LED tube. A first terminal of the safe capacitor CS is electrically coupled to the cathode of the diode D3 and the anode of the diode D4. A second terminal of the safe capacitor CS is electrically coupled to the third pin CON3 and the fourth pin CON4.

[0020] As mentioned above, the rectifier unit 103 of Fig. 2A has four diodes, which are D1, D2, D3 and D4 respectively. The filtering capacitor C2 of the power filter unit 104 allows the high frequency electric power to pass. The rectifier unit 103 provides bi-directional conduction current paths for the high frequency electric power, such that the high frequency electric power can be provided to the LED unit 101.

[0021] The current paths of the electric power in low frequency and in high frequency are respectively shown in Fig. 2B and Fig. 2C. When the electric power is the low frequency electric power, referring to Fig. 2B, the cycle of the electric power can be divided into a positive half-cycle and a negative half-cycle. Assume the current I1 in positive half-cycle of the electric power is inputted at the first pin CON1 shown in the left of the figure. Because of the high impedance of the first filtering capacitor C1 and the second filtering capacitor C2, the current I1 would flow into the filter 1021, the rectifier 1022 and the DC converter 1023, then return to the second pin CON2. In negative half-cycle, the current I2 is inputted at the second pin CON2, then flows into the filter 1021, the rectifier 1022 and the DC converter 1023, then returns to the first pin CON1. This situation of low frequency electric power can be applied to the exemplary applications of Fig. 8, Fig. 10 and Fig. 11 hereinafter. When the electric power is high frequency electric power, referring to Fig. 2C, in positive half-cycle, the current I3 is inputted to the first pin CON1 and the second pin CON2. Because the impedances of the first filtering capacitor C1 and the second filtering capacitor C2 are small, the current I3 would flow, through the second filtering capacitor C2 and the diode D1, to the LED unit 101. Then the current I3 flows, through the diode D3 and the safe capacitor CS, to the third pin CON3 or the fourth pin CON4. In negative half-cycle, the current I4 in inputted to the third pin CON3 and the fourth pin CON4. The current I4 flows, through the safe capacitor CS and the diode D4, to the LED unit 101. Then the current I4 flows through the diode D2, then flows through the second filtering capacitor C2 to the first pin CON1 (or further to the second pin CON2 through the first filtering capacitor C1). The described high frequency electric power situation can be applied to exemplary applications of Fig. 6 and Fig. 9 hereinafter.

[Another embodiment of a universal LED tube and a power system of the universal LED tube]

[0022] Please refer to Fig. 1A in conjunction with Fig. 3A. Fig. 3A shows a circuit diagram of an LED driving circuit of a universal LED tube according to another embodiment of the instant disclosure. Based on the architecture of the circuit of Fig. 1A, a power filter unit 104' and a rectifier unit 103' of Fig. 3A respectively replaces the power filter unit 104 and the rectifier unit 103 of Fig. 2A. That is, the two diodes D1, D2 of the rectifier unit 103 shown in Fig. 2A are replaced by a full-bridge rectifier. Also, the two filtering capacitors C1, C2 shown in Fig. 2A are replaced by three filtering capacitors Ca, Cb, Cc.

[0023] The filtering capacitor Ca is electrically coupled between the first pin CON1 and the second pin CON2, for isolating the high frequency electric power, and conducting the low frequency electric power. That is, the filtering capacitor Ca is the same as the filtering capacitor C1 shown in Fig. 2A. Filtering capacitors Cb, Cc replace the filtering capacitor C2 shown in Fig. 2A. The filtering capacitor Cb is electrically coupled between the second pin CON2 and the rectifier unit 103. The filtering capacitor Cc is electrically coupled between the first pin CON1 and the rectifier unit 103. The filtering capacitor Cb and the filtering capacitor Cc are used for isolating the low frequency electric power, and conducting the high frequency electric power.

[0024] The mentioned full-bridge rectifier comprises four diodes Da, Db, Dc, and Dd. The diodes D3 and D4 of Fig. 2A are reserved without change (which are presented by diodes De and Df in Fig. 3A). That is, the rectifier unit 103' of this embodiment comprises a full-bridge rectifier composed of four didoes Da, Db, Dc, Dd and additional two diodes De and Df. There are six diodes in total. The cathode of the diode Da is electrically coupled to the second pin CON2 through the filtering capacitor Cb, the anode of the diode Da is electrically coupled to the negative terminal 101b of the LED unit 101. The cathode of the diode Db is electrically coupled to the first pin CON1 through the filtering capacitor Cc, and the anode of the diode Db is electrically coupled to the negative terminal 101b of the LED unit 101. The cathode of the diode Dc is electrically coupled to the positive terminal 101a of the LED unit 101, the anode of the third diode Dc is electrically coupled to the second pin CON2 through the filtering capacitor Cb. The cathode of the diode Dd is electrically coupled to the positive terminal 101a of the LED unit 101, the anode of the diode Dd is electrically coupled to the first pin CON1 through the filtering capacitor Cc.

[0025] When the electric power is the low frequency electric power, the current path can be referred to in the descriptions of Fig. 2B. This redundant information is not repeated. The situation of low frequency electric power can be applied to the exemplary applications of Fig. 8, Fig. 10 and Fig. 11 hereinafter. When the electric power is the high frequency electric power, the current paths are shown in Fig. 3B and Fig. 3C. Referring to Fig. 3B, in positive half-cycle, the current I5 in inputted to the first pin CON1 or the second pin CON2, and a majority of the current flows, through the filtering capacitor Cb or the filtering capacitor Cc, to the rectifier unit 103'. The current flowing through the filtering capacitor Cb further flows through the diode Dc to the LED unit 101, or the current flowing through the filtering capacitor Cc further flows through the diode Dd to the LED unit 101. Then the current I5 flows, through the diode De and the safe capacitor CS, to the third pin CON3 or the fourth pin CON4. In negative half-cycle, referring to Fig. 3C, the current I6 is inputted to the third pin CON3 and the fourth pin CON4. Then the current I6 flows through the safe capacitor CS and the diode Df to the LED unit 101. The current I6 then flows through the diodes Da and Db, and then flows through the filtering capacitors Cb and Cc. The described high frequency electric power situation can be applied to exemplary applications of Fig. 6 and Fig. 9 hereinafter.

[Another embodiment of a universal LED tube and a power system of the universal LED tube]

[0026] Please refer to Fig. 3A in conjunction with Fig. 4. Fig. 4 shows a circuit diagram of an LED driving circuit of a universal LED tube according to another embodiment of the instant disclosure. For the DC converter 1023' of power converter unit 102' of Fig. 4, it is only replacing the DC converter 1023 of Fig. 3A by a buck converter. For ease of drawing in Fig. 4, the position of the positive terminal 101a and the position of the negative terminal 101b are exchanged. In Fig. 4, the positions of the diode De and the diode Df are also changed accordingly. However, the anode of the diode De is still electrically coupled to the negative terminal 101b of the LED unit 101. The cathode of the diode Df is still electrically coupled to the positive terminal 101a of the LED unit 101. In other words, the circuit architecture of the rectifier 103' is substantially the same, nothing is changed.

[0027] When the electric power is the low frequency electric power, the current path can be referred to in the descriptions about Fig. 2B, thus the redundant information is not repeated. The difference is only replacing the DC converter 1023 from a buck-boost converter to a buck converter. The low frequency electric power situation can be applied to exemplary applications shown in Fig. 8, Fig. 10 and Fig. 11. The current paths of the high frequency electric power are sustainably the same as the paths shown in Fig. 3B and Fig. 3C, thus the redundant information is not repeated. The high frequency electric power situation can be applied to exemplary applications shown in Fig. 6 and Fig. 9 hereinafter.

[Another embodiment of a universal LED tube and a power system of the universal LED tube]

[0028] Please refer to Fig. 5 in conjunction with Fig. 2A. Fig. 5 shows a circuit diagram of an LED driving circuit of a universal LED tube according to another embodiment of the instant disclosure. For the DC converter 1023' of power converter unit 102' of Fig. 5, it is only replacing the DC converter 1023 of Fig. 2A by a buck converter. And, compared with Fig. 2A, the position of the positive terminal 101a of the LED unit 101 and the position of the negative terminal 101b of the LED unit 101 are exchanged in Fig. 5. Also, in Fig. 5, the positions of the diode D3 and the diode D4 are changed accordingly. However, the anode of the diode D3 is still electrically coupled to the negative terminal 101b of the LED unit 101. The cathode of the diode D4 is still electrically coupled to the positive terminal 101a of the LED unit 101. In other words, the circuit architecture of the rectifier 103 is substantially the same, nothing is changed.

[0029] When the electric power is the low frequency electric power, the current path can be referred to in the descriptions about Fig. 2B, thus the redundant information is not repeated. The difference is only replacing the DC converter 1023 from a buck-boost converter to a buck converter. The low frequency electric power situation can be applied to exemplary applications shown in Fig. 8, Fig. 10 and Fig. 11. The current paths of the high frequency electric power are sustainably the same as the paths shown in Fig. 2C, thus the redundant information is not repeated. The high frequency electric power situation can be applied to exemplary applications shown in Fig. 6 and Fig. 9 hereinafter.

[Applications of the embodiments of the universal LED tube]

[0030] Please refer to Fig. 1A in conjunction with Fig. 6. Fig. 6 shows a simplified circuit of a conventional fluorescent tube using a self-excited high frequency electronic ballast. An element C5 indicates an electronic ballast, for connecting with a conventional fluorescent tube 2 in parallel, and for providing the high frequency electric power. For the circuit viewpoint, the impedance between the first pin CON1 and the second pin CON2 of the conventional fluorescent tube 2 is considered as a resistor. The impedance between the third pin CON3 and the fourth pin CON4 of the conventional fluorescent tube 2 is also considered as a resistor. The universal LED tube 1 of this instant disclosure can be completely applied to the circuit architecture of the conventional fluorescent tube, in order to completely replace the conventional fluorescent tube 2. When utilizing the universal LED tube 1 of the instant disclosure to replace the conventional fluorescent tube 2, the circuit architecture can be referred to in Fig. 7A, Fig. 7B, Fig. 7C and Fig. 7D. The LED driving circuit of the universal LED tube shown in Fig. 7A is the circuit shown in Fig. 3A. The LED driving circuit of the universal LED tube shown in Fig. 7B is the circuit shown in Fig. 2A. The LED driving circuit of the universal LED tube shown in Fig. 7C is the circuit shown in Fig. 5. The LED driving circuit of the universal LED tube shown in Fig. 7D is the circuit shown in Fig. 4. Because the high frequency electric power is used as the power source, it can be seen that the rectifier unit 103 (or the rectifier unit 103') is used to provide the high frequency electric power current path to provide electric power to the LED unit 101 when replacing the conventional fluorescent tube 2 by the universal LED tube 1 of this instant disclosure.

[0031] Please refer to Fig. 1A in conjunction with Fig. 8. Fig. 8 shows a circuit diagram of a conventional fluorescent tube using a magnetic ballast. Cooperating with the current stabilization of the inductor L, the conventional fluorescent tube 2 can be started by using the starter S, and then the conventional fluorescent tube 2 can be continuously conducted for emitting light after start. In this case, for the conventional fluorescent tube 2, the provided power is the low frequency electric power. In the same way, the conventional fluorescent tube 2 can be replaced by the universal LED tube 1 of this instant disclosure. That is, the circuits shown in Fig. 2A, Fig. 3A, Fig. 4 and Fig. 5 can replace the circuit of the conventional fluorescent tube 2 of Fig. 8. Because the circuits of Fig. 2A, Fig. 3A, Fig. 4 and Fig. 5 can be applied to Fig. 8 directly, the drawing of the circuits is omitted to avoid repeated descriptions. When replacing the conventional fluorescent tube 2 by the universal LED tube 1 of this instant disclosure, the power converter unit 102 (or the power converter unit 102') can obtain the low frequency electric power and convert the low frequency electric power to a DC power for lighting the LED unit 101.

[0032] Please refer to Fig. 1A in conjunction with Fig. 9. Fig. 9 shows a circuit diagram of a conventional fluorescent tube using an isolated external-exciting electronic ballast. An inductor T21 and an inductor T22 constitute a transformer. The transformer cooperates with inductors T11, T12, T23, T24 and switches Q1, Q2 to achieve a circuit of an external-excited electronic ballast. The circuit of an external-excited electronic ballast is powered by the high frequency electric power. In the same way, the conventional fluorescent tube 2 can be replaced by the universal LED tube 1 of the instant disclosure. That is, the circuits shown in Fig. 2A, Fig. 3A, Fig. 4 and Fig. 5 can replace the circuit of the conventional fluorescent tube 2 shown in Fig. 9. The drawing of the circuits is omitted to avoid repeated descriptions. When replacing the conventional fluorescent tube 2 by the universal LED tube 1 of this instant disclosure, the rectifier unit 103 (or the rectifier unit 103') can be used to provide current paths of high frequency electric power for providing power to the LED unit 101.

[0033] Please refer to Fig. 1A in conjunction with Fig. 10. Fig. 10 shows a schematic diagram of a universal LED tube applied to the architecture of single-ended power feeding according to another embodiment of the instant disclosure. When the conventional fluorescent tube 2 is a fluorescent tube with power feeding in a single-end, the fluorescent tube is usually power fed from two pins of one of its side portions. For example, in Fig. 10, the first pin CON1 and the second pin CON2 are used to establish the power providing loop. In this situation, no ballast is used, and the household electricity is directed to be used as the power source. It can be seen that the provided electric power is the low frequency electric power. The drawing of the circuits is omitted to avoid repeated descriptions. When replacing the conventional fluorescent tube 2 by the universal LED tube 1 of this instant disclosure, the power converter unit 102 (or the power converter unit 102') can be used to provide electric power to the LED unit 101.

[0034] Please refer to Fig. 1A in conjunction with Fig. 11. Fig. 11 shows a schematic diagram of a universal LED tube applied to architecture without starter according to another embodiment of the instant disclosure. By simply shorting the starter S, the conventional fluorescent tube 2 can be replaced by the universal LED tube 1 of this instant disclosure. By using the simple circuit modification, the third pin CON3 and the first pin CON1 are shorted, such that the first pin CON1 and the second pin CON2 can act as the power terminals for obtaining electric power. For the third pin CON3 and the fourth pin CON4, the safe capacitor CS (referring to Fig. 2A) is used to isolate low frequency electric power. The drawing of the circuits is omitted to avoid repeated descriptions. When replacing the conventional fluorescent tube 2 by the universal LED tube 1 of this instant disclosure, the power converter unit 102 (or the power converter unit 102') can be used to provide electric power to the LED unit 101. According to aforementioned applications, the universal LED tube 1 of this instant disclosure can be applied to a variety of kinds of tube holders for the existing conventional fluorescent tube 2, so as to replacing the conventional fluorescent tube 2.

[0035] According to above descriptions, the provided universal LED tube and the power system of the universal LED tube provide path planning for the current of different frequency, in order to provide different current paths. Applications for replacing the conventional fluorescent tube operating with magnetic ballast or electronic ballast can be realized, without modifying the wiring of the tube holder. Accordingly, wire modification cost of installing the LED tube can be avoided (or decreased).

[0036] The descriptions illustrated supra set forth simply the preferred embodiments of the instant disclosure; however, the characteristics of the instant disclosure are by no means restricted thereto. All changes, alterations, or modifications conveniently considered by those skilled in the art are deemed to be encompassed within the scope of the instant disclosure delineated by the following claims.

Claims

1. A universal LED tube, utilizing an external electric power to emit light, the external electric power being selectably a low frequency electric power, the universal LED tube having a first side portion (1a) and a second side portion (1b), and the universal LED tube further comprising:

a LED unit (101); and

a LED driving circuit coupled to the LED unit (101), the first side portion (1a) and the second side portion (1b), so as to drive the LED unit (101) lighting by the external electric power, the LED driving circuit comprising:

a power converter unit (102, 102'), electrically coupled to the LED unit (101), providing a DC power to the LED unit (101) according to the low frequency electric power;

a power filter unit (104, 104'), electrically coupled to the first side portion (1a) and electrically coupled to the power converter unit (102, 102'), wherein the low frequency electric power passes from the first side portion (1a) through the power filter unit (104, 104') to the power converter unit (102, 102'), so as to drive the LED unit (101) to emit light according to the low frequency electric power.

2. The universal LED tube according to claim 1, wherein the first side portion (1a) has a first pin (CON1) and a second pin (CON2), and the power converter unit (102, 102') comprises:

a filter (1021), electrically coupled to the first pin (CON1) and the second pin (CON2) through the power filter unit (104, 104');

a rectifier (1022), electrically coupled to the filter (1021); and

a DC converter (1023, 1023'), electrically coupled between the rectifier (1022) and the LED unit (101), providing the DC power to the LED unit (101) according to the rectified low frequency electric power.

3. The universal LED tube according to claim 1, wherein the external electric power further being selectably a high frequency electric power, the universal LED tube further comprising:

a rectifier unit (103, 103'), electrically coupled to the second side portion (1b), and electrically coupled to the LED unit (101) and the power filter unit (104, 104'), the rectifier unit (103, 103') rectifying the high frequency electric power, and providing the rectified high frequency electric power to the LED unit (101), so as to drive the LED unit (101) emit light according to the high frequency electric power.

4. The universal LED tube according to claim 3, wherein the first side portion (1a) has a first pin (CON1) and a second pin (CON2), and the power filter unit (104) comprises:

a first filtering capacitor (C1), electrically coupled between the first pin (CON1) and the second pin (CON2); and

a second filtering capacitor (C2), electrically coupled between the first pin (CON1) and the rectifier unit (103).

5. The universal LED tube according to claim 4, wherein the LED unit (101) has a positive terminal (101a) and a negative terminal (101b), a conducting current of the LED unit (101) flows from the positive terminal (101a) of the LED unit (101) to the negative terminal (101b) of the LED unit (101), wherein the rectifier unit (103) comprises:

a first diode (D1), an anode of the first diode (D1) electrically coupled to the first pin (CON1) through the second filtering capacitor (C2), and a cathode of the first diode (D1) electrically coupled to the positive terminal (101a) of the LED unit (101); and

a second diode (D2), a cathode of the second diode (D2) electrically coupled to the first pin (CON1) through the second filtering capacitor (C2), and an anode of the second diode (D2) electrically coupled to the negative terminal (101b) of the LED unit (101).

6. The universal LED tube according to claim 5, wherein the second side portion has a third pin and a fourth pin, the rectifier unit further comprises:

a third diode (D3), an anode of the third diode (D3) electrically coupled to the negative terminal (101b) of the LED unit (101), a cathode of the third diode (D3) electrically coupled to the third pin (CON3) and the fourth pin (CON4); and

a fourth diode (D4), a cathode of the fourth diode (D4) electrically coupled to the positive terminal (101a) of the LED unit (101), an anode of the fourth diode (D4) electrically coupled to the third pin (CON3) and the fourth pin (CON4).

7. The universal LED tube according to claim 6, further comprising:

a safe capacitor (CS), having a first terminal and a second terminal, the first terminal of the safe capacitor (CS) electrically coupled to the cathode of the third diode (D3) and the anode of the fourth diode (D4), the second terminal of the safe capacitor (CS) electrically coupled to the third pin (CON3) and the fourth pin (CON4).

8. The universal LED tube according to claim 3, wherein the first side portion (1a) has a first pin (CON1) and a second pin (CON2), and the power filter unit (104') comprises:

a first filtering capacitor (Ca), electrically coupled between the first pin (CON1) and the second pin (CON2);

a second filtering capacitor (Cb), electrically coupled between the second pin (CON2) and the rectifier unit (103'); and

a third filtering capacitor (Cc), electrically coupled between the first pin (CON1) and the rectifier unit (103').

9. The universal LED tube according to claim 8, wherein the LED unit (101) has a positive terminal (101a) and a negative terminal (101b), the conducting current of the LED unit (101) flows from the positive terminal (101a) of the LED unit (101) to the negative terminal (101b) of the LED unit (101), wherein the rectifier unit (103') comprises:

a first diode (Da), a cathode of the first diode (Da) electrically coupled to the second pin (CON2) through the second filtering capacitor (Cb), and an anode of the first diode (Da) electrically coupled to the negative terminal (101b) of the LED unit (101);

a second diode (Db), a cathode of the second diode (Db) electrically coupled to the first pin (CON1) through the third filtering capacitor (Cc), and an anode of the second diode (Db) electrically coupled to the negative terminal (101b) of the LED unit (101);

a third diode (Dc), a cathode of the third diode (Dc) electrically coupled to the positive terminal (101a) of the LED unit (101), and an anode of the third diode (Dc) electrically coupled to the second pin (CON2) through the second filtering capacitor (Cb); and

a fourth diode (Dd), a cathode of the fourth diode (Dd) electrically coupled to the positive terminal (101a) of the LED unit (101), and an anode of the fourth diode (Dd) electrically coupled to the first pin (CON1) through the third filtering capacitor (Cc).

10. The universal LED tube according to claim 9, wherein the second side portion (1b) has a third pin (CON3) and a fourth pin (CON4), and the rectifier unit (103') further comprises:

a fifth diode (De), an anode of the fifth diode (De) electrically coupled to the negative terminal (101b) of the LED unit (101), and a cathode of the fifth diode (De) electrically coupled to the third pin (CON3) and the fourth pin (CON4); and

a sixth diode (Df), a cathode of the sixth diode (Df) electrically coupled to the positive terminal (101a) of the LED unit (101), and an anode of the sixth diode (Df) electrically coupled to the third pin (CON3) and the fourth pin (CON4).

11. The universal LED tube according to claim 9, further comprising:

a safe capacitor (CS), having a first terminal and a second terminal, the first terminal of the capacitor (CS) electrically coupled to the cathode of the fifth diode (De) and the anode of the sixth diode (Df), the second terminal of the capacitor (CS) electrically coupled to the third pin (CON3) and the fourth pin (CON4).

12. A power system, comprising:

a tube holder, providing an external electric power; and

a universal LED tube according to claim 1, connected to the tube holder.

13. A power system of a universal LED tube, comprising:

a tube holder, providing an external electric power; and

a universal LED tube according to claim 3, connected to the tube holder.

14. The power system according to claim 12 or 13, further comprising:

an electronic ballast installed on the tube holder.

15. The power system according to claim 12 or 13, further comprising:

a starter installed on the tube holder.

16. The power system according to claim 12 or 13, wherein the tube holder is without any electronic ballast or starter.

Drawing