KR200451055Y1 - Backlight apparatus - Google Patents

Abstract

The present invention discloses a backlight device. The backlight device includes a power supply, a lamp, a balance transformer, a detection circuit, a determination module, and a control module. The balance transformer includes a primary winding electrically connected to the power supply and a secondary winding corresponding to the primary winding and electrically connected to the lamp. The detection circuit is used to detect the current generated by the secondary winding and generate a first voltage in accordance with the current. The determining module is used to determine whether the first voltage value is smaller than a default value. The control module is used to control the power source according to the determination of the determination module.

Balanced Transformer, Wirewound, Full-Bridge Circuit, Half-Bridge Circuit

Description

Backlight apparatus

The present invention relates to a backlight device, and more particularly, to a backlight device capable of short-circuit prevention and voltage feedback compensation by changing a connection pattern of a balance transformer circuit without an additional capacitor.

Recently, with the development of increasing the size of liquid crystal display (LCD) panels, a backlight device having multiple cold cathode fluorescent lamps (CCFLs) has been widely applied as a high quality light source of LCD panels.

Referring to FIG. 1, FIG. 1 is a diagram illustrating a conventional backlight device having a balance circuit capable of short-circuit prevention and voltage feedback compensation. As shown in FIG. 1, the backlight device 1 is mounted on a double-sided printed circuit board (PCB) to handle multiple capacitors and resistors as a voltage divider on the secondary side of the balance transformer 14. To determine whether the balance circuit is short, the voltage at node A is measured and compared with the default value in FIG. In addition, at node B of FIG. 1, in order to obtain voltage feedback compensation, the kick-off voltage is measured to adjust the voltage provided by the power source 10.

In the balance circuit described above, many capacitors and resistors are needed to obtain short circuit protection and voltage feedback compensation. However, additional factors increase complex circuit and product costs. In addition, because of that, the capacitors used for the double-sided PCB do not apply to the single-sided PCB. Thus, the backlight device on the single-sided PCB cannot obtain short circuit protection and voltage feedback compensation by the prior art.

The present invention discloses a backlight device capable of short-circuit prevention and voltage feedback compensation by changing a connection pattern of a balance transformer circuit, without an additional capacitor, in order to solve the aforementioned problem.

The field of the present invention is to provide a backlight device. According to an embodiment, the backlight device includes a power supply, a lamp, a balance transformer, a detection circuit, a determination module, and a control module.

Balanced transformers include a primary winding and a secondary winding. The primary winding is electrically connected to the power source. The secondary winding is electrically connected to the lamp and corresponds to the primary winding. The detection circuit is electrically connected with the secondary winding and is used to detect the current generated by the secondary winding and generate a first voltage according to the current. The determination module is electrically connected with the detection circuit and is used to determine whether the first voltage value is less than the default value. The control module is electrically connected to the power source and the determination module, and is used to control the power source according to the determination of the determination module.

Compared with the prior art, the backlight device of the present invention can obtain short circuit prevention in the balance circuit and real signal voltage feedback compensation in the closed loop of a single-sided printed circuit board (PCB). More importantly, the backlight device of the present invention can achieve the aforementioned purpose only by changing the connection pattern of the balance transformer circuit. Thus, it can save a lot of capacitors and resistors, and reduce the product cost.

Advantages and spirit of the present invention will be understood by the following description in conjunction with the accompanying drawings.

A first embodiment of the present invention is a backlight device. Referring to FIG. 2, FIG. 2 is a schematic diagram illustrating a first embodiment of a backlight device.

The backlight device 2 includes a power supply 20, a lamp 22, a balance transformer 24, a detection circuit 26, a determination module 28, a first impedance 23, a second impedance 25, and a measurement module. 27, and a control module 29. Since the balance transformer 24 corresponds to only one lamp (lamp 22), the balance transformer 24 is a one-balance-transformer-to-one-lamp. (1 to 1).

The following is a detailed description of the interrelation and function of each unit included in the multi-lamp backlight device 2.

The balance transformer 24 includes a primary winding 242 and a secondary winding 244. Primary winding 242 is electrically connected to power source 20. The secondary winding 244 corresponds to the primary winding 242 and is electrically connected to the lamp 22.

In FIG. 2, the detection circuit 26 is electrically connected to the secondary winding 244 of the balance transformer 24 and used to detect current and generate a first voltage according to the current. The above current is generated by the secondary winding 244. In fact, the current in the secondary winding 244 is an induced current coming from the current through the primary winding 242 and causes induction in the secondary winding 244.

It should be noted that the detection circuit 26 employs a center-tapped connection pattern to connect with the secondary winding 244 of the balance transformer 24. In practical applications, the connecting terminal extends from the middle of the secondary winding 244 and forms from the secondary winding 244 the upper portion of the winding and the lower portion of the winding in a ratio of about 100: 1.

The determination module 28 is electrically connected to the detection circuit 26 and is used to determine whether the first voltage value is smaller than the default value. In a practical application, assuming a default value of zero, if the determination of decision module 28 is positive, the first voltage value represents zero. That is, the detection circuit 26 is a short circuit.

The control module 29 is electrically connected to the power supply 20 and the determination module 28 and used to control the power supply 20 according to the determination of the determination module 28. In practical application, the control module includes a full-bridge circuit or a half-bridge circuit. If the determination of the determination module 28 is positive, this means that the detection circuit 26 is short-circuited, and the control module 29 will turn off the power to protect the backlight device 2.

In addition, the backlight device further includes a first impedance 23, a second impedance 25, and a measurement module 27, as shown in FIG. 2. In practical applications, each of the first impedance 23 and the second impedance 25 may be a resistive element.

The first impedance 23 is electrically connected to the secondary winding 244, which generates a current through the first impedance 23. The second impedance 25 is connected to the first impedance 23.

The measuring module 27 is connected between the first impedance 23 and the second impedance 25 and is used to measure the second voltage value between the first impedance 23 and the second impedance 25. In fact, the second voltage value measured by the measurement module 27 is the kick-off voltage value. The kick-off voltage value is the minimum voltage value for activating the ramp 22.

The control module 29 is electrically connected to the power supply 20 and the measurement module 27 and used to control the voltage provided by the power supply 20 according to the second voltage value. In this way, voltage feedback compensation is obtained in a closed loop. In fact, the control module may comprise a full-bridge circuit or a half-bridge circuit.

 See FIG. 3, except that the connection pattern of the detection circuit 26 in FIG. 2 adopts a mid-tap connection pattern connecting with the secondary winding 244 of the balance transformer 24, FIG. 3 shows a balance transformer. Schematic diagram illustrating another connection pattern of the backlight device of FIG. 2 for dividing secondary winding 344 into first secondary winding 3442 and second secondary winding 3444 at 34.

In FIG. 3, the first secondary winding 3442 corresponds to the primary winding 342 and is coupled to the lamp 32 and used to generate a drive current to drive the lamp 32.

The second secondary winding 3444 corresponds to the primary winding 342 and is connected to the detection circuit 36, which is used to transmit drive current to the detection circuit 36. In addition, the second secondary winding 3444 may be coupled with the first impedance 33 for generating a current through the first impedance 33. The connection pattern shown in FIG. 3 connects the detection circuit 36 or the first impedance 33 with the second secondary winding 3444, which is called the third winding method.

The measurement module 37 measures the second voltage value between the first impedance 33 and the second impedance 35. Later, the control module 39 will control the power supply 30 according to the second voltage value measured by the measuring module 37.

The second embodiment of the present invention is also a backlight device. Referring to FIG. 4, FIG. 4 is a schematic diagram illustrating a second embodiment of the backlight device.

In FIG. 4, the backlight device 4 includes a power supply 40, a first lamp 41, a second lamp 42, a balance transformer 44, a first detection circuit 461, and a second detection circuit 462. , The determination module 48, the first impedance 43, the second impedance 45, the measurement module 47, and the control module 49. Since the balance transformer 44 corresponds to two lamps (the first lamp 41 and the second lamp 42), the balance transformer 44 is a one-balance-transformer-to-to-lamp. -transformer-to-two-lamp).

The following is a detailed description of the interrelation and function of each unit included in the multi-lamp backlight device 4.

The balance transformer 44 includes a primary winding 442, a first secondary winding 444, and a second secondary winding 446. Primary winding 442 is electrically connected to power source 40. The first secondary winding 444 corresponds to the primary winding 442 and is connected to the first lamp 41. The second secondary winding 446 corresponds to the primary winding 442 and is connected to the second lamp 42.

Each of the first detection circuit 461 and the second detection circuit 462 is connected to the first secondary winding 444 and the second secondary winding 446 of the balance transformer 44 while the first secondary winding is connected. It is used to measure each of the first current generated by 444 and the second current generated by the second secondary winding 44. At this time, the detection circuits generate a first voltage according to the first current and the second current. In fact, both the first current and the second current are induced currents.

In FIG. 4, the first detection circuit 461 and the second detection circuit 462 are mid-taps for connecting with the first secondary winding 444 and the second secondary winding 446 of the balance transformer 44. It should be recognized that it adopts a connection pattern.

The determination module 48 is electrically connected to the first detection circuit 461 and the second detection circuit 462, and is used to determine whether the first voltage value is smaller than the default value. Based on that, the determination module 48 may determine whether the first detection circuit 461 and the second detection circuit 462 are short-circuited.

The control module 49 is electrically connected to the power supply 40 and the determination module 48 and used to control the power supply 40 according to the determination of the determination module 48. In practical application, the control module 49 may include a full-bridge circuit or a half-bridge circuit. If the determination by the determination module 48 is positive, the control module 49 will turn off the power supply 40 to protect the backlight device 4.

In addition, the backlight device 4 includes a first impedance 43, a second impedance 45, and a measurement module 47. In practical applications, each of the first impedance 43 and the second impedance 45 may be a resistive element.

The first impedance 43 is electrically connected to the first secondary winding 444 and the second secondary winding 446. The current flow through the first impedance 43 includes a first current generated by the first secondary winding 444 and a second current generated by the second secondary winding 446. The second impedance 45 is connected to the first impedance 43.

The measurement module 47 is connected between the first impedance 43 and the second impedance 45, and is used to measure the second voltage value between the first impedance 43 and the second impedance 45. In fact, the second voltage value measured by the measurement module 47 is the kick-off voltage for activating the lamp.

The control module 49 is electrically connected to the power supply 40 and the measurement module 47 and used to control the voltage provided by the power supply 40 in accordance with the second voltage value. In this way, voltage feedback compensation is obtained in a closed loop.

See FIG. 5. Except for the mid-tap connection pattern of FIG. 4, FIG. 5 divides the first secondary winding 544 into a first sub-winding 5442 and a second sub-winding 5444 in the balance transformer 54. 4 is a schematic diagram illustrating another connection pattern with the backlight device of FIG. 4.

In FIG. 5, the first sub-winding 5442, corresponds to the primary winding 542 and is connected to the first lamp 51, is used to generate a drive current for driving the first lamp 51. .

The second sub-winding 5444 corresponds to the primary winding 542 and is connected to the detection circuit 56. In addition, the second sub-winding 5444 may be connected with the first impedance 53 and used to generate a current flowing through the first impedance 53. The connection pattern shown in FIG. 5 is a third winding method.

Moreover, the second secondary winding 546 may be divided into a third sub-winding 5542 and a fourth sub-winding 5546. The connection pattern is the same as the pattern mentioned above.

The measurement module 57 measures the second voltage value between the first impedance 53 and the second impedance 55. Later, the control module 59 will control the power supply 50 according to the second voltage value measured by the measurement module 57.

 The third embodiment of the present invention is also a backlight device. Referring to FIG. 6, FIG. 6 is a schematic diagram illustrating a third embodiment of the backlight device.

In FIG. 6, the backlight device 6 includes a power supply 60, a first lamp 621, a second lamp 622, a third lamp 623, a balance transformer 64, a first detection circuit 661, The second detection circuit 662, the third detection circuit 663, the fourth detection circuit 664, the determination module 68, the first impedance 63, the second impedance 65, the measurement module 67, And a control module 69. Since the balance transformer 44 corresponds to four lamps (the first lamp 621, the second lamp 622, the third lamp 623, and the fourth lamp 624), the balance transformer 64 is a circle. Balance-transformer-to-four-lamp (1 to 4).

The following is a detailed description of the interrelation and function of each unit included in the multi-lamp backlight device 6.

The balance transformer 64 connects the primary winding 642, the first secondary winding 644, the second secondary winding 646, the third secondary winding 648, and the fourth secondary winding 649. Include. Primary winding 642 is electrically connected to power source 60. The first secondary winding 644 corresponds to the primary winding 642 and is connected to the first lamp 621. The second secondary winding 646 corresponds to the primary winding 642 and is connected to the second lamp 622. The third secondary winding 648 corresponds to the primary winding 642 and is connected to the third lamp 623. The fourth secondary winding 649 corresponds to the primary winding 642 and is connected to the fourth lamp 624.

Each of the first detection circuit 661, the second detection circuit 662, the third detection circuit 663, and the fourth detection circuit 664 may include the first secondary winding 664 and the first detection circuit of the balance transformer 64. A second secondary winding 646, a third secondary winding 648, and a fourth secondary winding 649. The detection circuits described above include the first current generated by the first secondary winding 644, the second current generated by the second secondary winding 646, and the first generated by the third secondary winding 648. It is used to detect each of the three currents and the fourth current generated by the fourth secondary winding 649. At this time, the detection circuits generate a first voltage according to the first current, the second current, the third current, and the fourth current. In fact, the first current, second current, third current, and fourth current are all induced currents.

In FIG. 6, the balance transformer 64 includes a first secondary winding 644, a second secondary winding 646, a third secondary winding 648, and a fourth secondary winding () of the balance transformer 64. It should be noted that it employs a mid-tap connection pattern to connect to 649).

The determination module 68 is electrically connected to the first detection circuit 661, the second detection circuit 662, the third detection circuit 663, and the fourth detection circuit 664. Used to determine if it is less than the default value. Based on that, the judging module 68 can determine whether the above detection circuits are short-circuited.

The control module 69 is electrically connected to the power supply 60 and the determination module 68 and used to control the power supply 60 in accordance with the determination by the determination module 68. If it is determined that the detection circuit 66 is shorted, the control module 69 will turn off the power supply 60 to protect the backlight device 6.

In addition, the backlight device 6 includes a first impedance 63, a second impedance 65, and a measurement module 67. In practical applications, each of the first impedance 63 and the second impedance 65 may be a resistive element.

The first impedance 63 is electrically connected to the first secondary winding 644, the second secondary winding 646, the third secondary winding 648, and the fourth secondary winding 649. The current flow through the first impedance 63 may include a first current generated by the first secondary winding 644, a second current generated by the second secondary winding 646, and a third secondary winding ( Third current generated by 648, fourth current generated by fourth secondary winding 649. The second impedance 65 is connected to the first impedance 63.

The measurement module 67 is connected between the first impedance 63 and the second impedance 65 and used to measure the second voltage value between the first impedance 63 and the second impedance 65. In fact, the second voltage value measured by the measurement module 67 is the kick-off voltage value for activating the lamp.

The control module 69 is electrically connected to the power supply 60 and the measurement module 67 and used to control the voltage provided by the power supply 60 in accordance with the second voltage value. In this way, voltage feedback compensation is obtained in a closed loop.

Referring to FIG. 7, except for the mid-tap connection pattern of FIG. 6, FIG. 7 shows the first secondary winding 744 in the balance transformer 74 with the first sub-winding 7242 and the second sub-. Schematic diagram illustrating another connection pattern of the backlight device shown in FIG. 6 for dividing by winding 7744.

In FIG. 7, the first sub-winding 7242 is associated with the primary winding 742 and connected with the first lamp 721 and used to generate a drive current for driving the first lamp 721. .

The second sub-wind 7744 corresponds to the primary winding 742 and is connected to the detection circuit 76. In addition, the second sub-winding 7204 may be connected with the first impedance 73 and used to generate a current flowing through the first impedance 73. The connection pattern shown in FIG. 7 is a third winding method.

First of all, each of the second secondary winding 746, the third secondary winding 748, and the fourth secondary winding 749 may include the third sub-winding 7262, the fourth sub-winding 7746, A fifth sub-winding 7262, a sixth sub-winding 7748, a seventh sub-winding 7742, and an eighth sub-winding 7494. The connection pattern is the same as the pattern mentioned above.

The measurement module 77 measures a second voltage value between the first impedance 73 and the second impedance 75. Later, the control module 79 will control the power supply 70 according to the second voltage value measured by the measurement module 77.

Compared with the prior art, the backlight device of the present invention can obtain short circuit prevention in a balanced circuit and real signal voltage feedback compensation in a closed loop of a single-sided printed circuit board (PCB). Most importantly, the backlight device of the present invention can achieve the aforementioned purpose only by changing the connection pattern of the balance transformer circuit. Thus, it can save many capacitors and resistors and reduce product cost.

Together with the examples and descriptions above, the features and spirit of the present invention are well described. Those skilled in the art will appreciate that many modifications and alternatives to the device can be implemented while maintaining the teachings of the present invention. Accordingly, the foregoing description should be construed as not limited to the limitations and boundaries of the appended claims.

1 is a schematic diagram illustrating a conventional backlight device having a balance circuit capable of short circuit protection and voltage feedback compensation.

2 is a schematic diagram illustrating a first embodiment of a backlight device.

3 is a schematic diagram illustrating another connection pattern of the backlight device illustrated in FIG. 2.

4 is a schematic diagram illustrating a second embodiment of the backlight device.

FIG. 5 is a schematic diagram illustrating another connection pattern of the backlight device illustrated in FIG. 4.

6 is a schematic diagram illustrating a third embodiment of the backlight device.

FIG. 7 is a schematic diagram illustrating another connection pattern of the backlight device illustrated in FIG. 6.

Claims (18)

power; lamp; A balance transformer having a primary winding electrically connected to the power source and a secondary winding corresponding to the primary winding and electrically connected to the lamp; A detection circuit electrically connected to the secondary winding, detecting a current generated by the secondary winding, and generating a first voltage according to the current; A determination module electrically connected to the detection circuit, and determining whether the first voltage value is smaller than a default value; And And a control module electrically connected to the power source and the determination module and controlling the power according to the determination by the determination module. The detection circuit uses a center-tapped connection pattern to be electrically connected with the secondary winding, Only one end of both ends of the secondary winding is connected to the lamp. The method of claim 1, The secondary winding. A first secondary winding corresponding to the primary winding and connected to the lamp and generating a driving current for driving the lamp; And And a second secondary winding corresponding to the primary winding and connected to the detection circuit and transmitting the current to the detection circuit. The method of claim 1, The control module includes a full-bridge circuit or a half-bridge circuit. power; lamp; A balance transformer having a primary winding electrically connected to the power source and a secondary winding corresponding to the primary winding and electrically connected to the lamp; A first impedance element electrically connected to the secondary winding, through which a current generated by the secondary winding flows; A second impedance coupled with the first impedance element; A measurement module coupled between the first impedance and the second impedance element and measuring a second voltage between the first impedance and the second impedance element; A control module electrically connected to the power supply and the measurement module and controlling the power supply according to the second voltage; And And a detection circuit electrically connected to the secondary winding using a center-tapped connection pattern. Only one end of both ends of the secondary winding is connected to the lamp. The method of claim 4, wherein The secondary winding, A first secondary winding corresponding to the primary winding and connected to the lamp and generating a driving current for driving the lamp; And And a second secondary winding corresponding to the primary winding and connected to the first impedance element and flowing through the first impedance element to generate the current. The method of claim 4, wherein The control module includes a full-bridge circuit or a half-bridge circuit. power; A first lamp; A second lamp; A primary winding electrically connected to the power source, a first secondary winding corresponding to the primary winding and electrically connected to the first lamp, and a second two corresponding to the primary winding and electrically connected to the second lamp A balance transformer with secondary windings; Electrically connected to the first secondary winding and the second secondary winding, detecting the first current generated by the first secondary winding and the second current generated by the second secondary winding, and A detection circuit generating a first voltage in accordance with a current and the second current; A determination module electrically connected to the detection circuit, and determining whether the first voltage value is smaller than a default value; And And a control module electrically connected to the power source and the determination module and controlling the power according to the determination by the determination module. The detection circuit uses a center-tapped connection pattern to be electrically connected with the first secondary winding and the second secondary winding, Only one end of both ends of the first secondary winding is connected to the first lamp, and only one end of both ends of the second secondary winding is connected to the second lamp. The method of claim 7, wherein The first secondary winding, A first sub-winding wire corresponding to the primary winding and connected to the first lamp, and generating a driving current for driving the first lamp; And And a second sub-winding wire corresponding to the primary winding and connected to the detection circuit. The method of claim 7, wherein The control module includes a full-bridge circuit or a half-bridge circuit. power; A first lamp; A second lamp; A primary winding electrically connected to the power source, a first secondary winding corresponding to the primary winding and electrically connected to the first lamp, and a second winding corresponding to the primary winding and electrically connected to the second lamp. A balance transformer with two secondary windings; A current electrically connected to the first secondary winding and the second secondary winding, the current comprising a first current generated by the first secondary winding and a second current generated by the second secondary winding A flowing first impedance element; A second impedance coupled with the first impedance element; A measurement module coupled between the first impedance and the second impedance element and measuring a second voltage between the first impedance and the second impedance element; A control module electrically connected to the power supply and the measurement module, the control module controlling the power supply according to the second voltage; And And a detection circuit electrically connected to the first secondary winding and the second secondary winding using a center-tapped connection pattern. Only one end of both ends of the first secondary winding is connected to the first lamp, and only one end of both ends of the second secondary winding is connected to the second lamp. The method of claim 10, The first secondary winding, A first sub-winding wire corresponding to the primary winding and connected to the first lamp, and generating a driving current for driving the first lamp; And And a second sub-winding wire corresponding to the primary winding and connected to the first impedance element, the second sub-winding generating current flowing through the first impedance element. The method of claim 10, The control module includes a full-bridge circuit or a half-bridge circuit. power; A first lamp; A second lamp; A third lamp; A fourth lamp; A primary winding electrically connected to the power source, a first secondary winding corresponding to the primary winding and electrically connected to the first lamp, a second corresponding to the primary winding and electrically connected to the second lamp A secondary winding, a third secondary winding corresponding to the primary winding and electrically connected to the third lamp, and a fourth secondary winding corresponding to the primary winding and electrically connected to the fourth lamp. Balance transformers; A first current generated by the first secondary winding, the first current electrically connected to the first secondary winding, the second secondary winding, the third secondary winding, and the fourth secondary winding; Used to detect a second current generated by a second secondary winding, a third current generated by the third secondary winding, and a fourth current generated by the fourth secondary winding, wherein the first current A detection circuit configured to generate a first voltage according to the second current, the third current, and the fourth current; A determination module electrically connected to the detection circuit, and determining whether the first voltage value is smaller than a default value; And And a control module electrically connected to the power source and the determination module and controlling the power according to the determination of the determination module. The detection circuit uses a center-tapped connection pattern to be electrically connected to the first secondary winding, the second secondary winding, the third secondary winding and the fourth secondary winding. Using, Only one end of both ends of the first secondary winding is connected to the first lamp, only one end of both ends of the second secondary winding is connected to the second lamp, and one end of both ends of the third secondary winding. A bay is connected to the third lamp, and only one end of both ends of the fourth secondary winding is connected to the fourth lamp. The method of claim 13, The first secondary winding, A first sub-winding wire corresponding to the primary winding and connected to the first lamp and generating a driving current to drive the first lamp; And And a second sub-winding wire corresponding to the primary winding and connected to the detection circuit. The method of claim 13, The control module includes a full-bridge circuit or a half-bridge circuit. power; A first lamp; A second lamp; A third lamp; A fourth lamp; A primary winding electrically connected to the power source, a first secondary winding corresponding to the primary winding and electrically connected to the first lamp, and a second winding corresponding to the primary winding and electrically connected to the second lamp. A second secondary winding, a third secondary winding corresponding to the primary winding and electrically connected to the third lamp, and a fourth secondary winding corresponding to the primary winding and electrically connected to the fourth lamp. One balance transformer; A first current generated by the first secondary winding, the second secondary winding electrically connected to the first secondary winding, the second secondary winding, the third secondary winding, and the fourth secondary winding A first impedance element through which a current flows including a second current generated by the third current, the third current generated by the third secondary winding, and a fourth current generated by the fourth secondary winding; A second impedance coupled with the first impedance element; A measurement module coupled between the first impedance and the second impedance element and measuring a second voltage between the first impedance and the second impedance element; A control module electrically connected to the power supply and the measurement module, the control module controlling the power supply according to the second voltage; And And a detection circuit electrically connected to the first secondary winding, the second secondary winding, the third secondary winding, and the fourth secondary winding using a center-tapped connection pattern. Only one end of both ends of the first secondary winding is connected to the first lamp, only one end of both ends of the second secondary winding is connected to the second lamp, and one end of both ends of the third secondary winding. Only a light is connected to the third lamp, and only one end of both ends of the fourth secondary winding is connected to the fourth lamp. The method of claim 16, The first secondary winding, A first sub-winding wire corresponding to the primary winding and connected to the first lamp, and generating a driving current for driving the first lamp; And And a second sub winding corresponding to the primary winding and connected to the first impedance element to generate the current flowing through the first impedance element. The method of claim 16, The control module includes a full-bridge circuit or a half-bridge circuit.

Images