TWI284766B - Backlight module - Google Patents

Abstract

A backlight module is provided. The backlight module includes a backlight source and an inverter. The backlight source includes a tube for generating a light and a rear board for reflecting the light. The rear board which is connected to ground is near the tube. The inverter is employed to drive the backlight source. The inverter includes a controller and a transformer. The controller receives a DC power and outputs a first AC power. The transformer includes a primary coil and a secondary coil. The primary coil is coupled to the controller and ground for receiving a first AC power. The secondary coil outputs a second AC power to a first terminal of the tube in response to the first AC power. First and second terminal of the secondary coil are respectively connected to the first and second terminal of the tube.

Description

1284766 _#^.,93113375_月日修正__ V. Description of the Invention (1) Technical Field of the Invention The present invention relates to a backlight module, and more particularly to a method for reducing leakage current (1 eakagecurrent ) The backlight module. [Prior Art] In a display device, liquid crystal display (LCD) has become a mainstream product of display devices in recent years due to its advantages of thin volume, light weight, and low electromagnetic radiation. The light source of the liquid crystal display is from a backlight module. The backlight module includes an inverter and a backlight. The inverter is used to convert the constant & stream power to an AC power source and drive the backlight accordingly. Please refer to FIG. 1 , which is a circuit diagram of a conventional backlight module. The backlight module 100 includes a backlight 11 〇 and a reverse inverter 1 2 〇. The backlight 丨丄〇 includes a lamp 11 2 and a back plate 11 4 located near the lamp 11 2 and electrically connected to the ground. The inverter 1 2 0 includes a control unit 1 2 2, a transformer 1 2 4 and a feedback unit 126. The feedback unit 126 includes a resistor R. The feedback unit 126 is coupled between the second end 1 1 2b of the lamp 11 2 and the ground for outputting the feedback signal fb to the control unit 122. The control unit 122 is configured to receive the DC voltage Dc and output the AC voltage AC according to the feedback signal FB. The transformer 1 24 includes a - under side coil 1 32 and a secondary side coil 1 34. The primary side coil 1 32 is coupled between the control unit 1 2 2 and the ground terminal to receive the AC voltage aC. The secondary side line 134 is coupled between the first end 112a of the bulb 112 and the ground. The second 'secondary side coil 1 34 senses the alternating voltage AC of the primary side coil 1 32, and the output is pressed.

Page 9 1284766 Case No. 93113375 Amendment 5. The alternating current It of the invention (2) to the lamp tube 112 to drive the lamp tube 112. However, today's liquid crystal displays use inverters to drive the backlights, which will make the size bigger and bigger, and the traditional efficiency is too low. Therefore, if the brightness of the J tube is uneven and the light is emitted and the luminous efficiency of the tube is increased, the tube can be more uniform and the direction of the force is improved. It is necessary for all relevant practitioners. [The invention has the purpose of achieving the purpose, root and anti-use of light. The reverse unit is based on the AC side coil and the AC current source. The following is the case. In view of this, it can be improved and can be used for commutation and voltage conversion of the backplane of the inverter. Electrical power supply. To the lamp, respectively, and the purpose of the present invention, the illumination of the lamp of the present invention is effective for the purpose of control. Backlight package. The backplane is used for the drive. The control single transformer includes a first connection to the control of the secondary side coil, the first purpose of the above-mentioned purpose is to improve the efficiency, and the flow through the lamp is proposed to be used to send "shoot* near the lamp, Backlight. The element is configured to receive the primary side coil unit and the grounding system according to the first, second and second ends, and the preferred embodiment, and provide a backlight module to more uniformly make the brightness and current of the lamp tube. The optical module includes a light tube and is electrically connected to the DC power supply of the inverter and the secondary side end, and is electrically connected by the AC power supply side coil. And the advantages can be more of a figure, the backlight and the anti-electrical connection include control and turn the lap. One time to receive the second end of the first intersection and the first obvious

Page 10 1284766 Case V. Invention Description (3) 93113375 Month g__ Amendment [Embodiment] Embodiment 1 Please refer to Figure 1 again. In Fig. 1, a series resistor R is connected between the second end 112b of the bulb 112 and the ground. Since the resistance value of the resistor R is usually very small, the voltage difference between the first end 11 2 b of the bulb 11 2 and the backing plate 11 4 is small. In this way, there will be a large voltage difference between the first end 11 2a of the lamp 11 2 and the back plate 11 4 , generally between 6 Ο Ο V 〜 1 2 Ο Ο V. This voltage difference will form a leakage current between the first end 11 2a of the lamp 11 2 and the back plate 11 4 to reduce the efficiency of use of the power source. More specifically, due to the voltage difference between the first end 11 2a of the lamp 11 2 and the back plate 11 4 , there is a parasitic capacitance C between the lamp tube Π 2 and the metal back plate 11 4 , so A small portion of the leakage current I 1 will flow from the first end 11 2a of the lamp 11 2 through the parasitic capacitor C to the back plate 1 14 and then to the ground terminal, as shown in FIG. 2 . In Fig. 2, the alternating current 11 is equal to the driving current I d for driving the lamp 11 2 to output light energy, and the leakage current I 1 flowing through the parasitic capacitor C to the ground. Therefore, the smaller, so - the larger the current I 1 , the 1 1 2 a is reduced to the unevenness of the lamp

When the leakage current I 1 is larger, the driving current I d is relatively opposite, and the luminous efficiency of the bulb 11 2 is worse. In addition, when the brightness of the lamp '1 1 2 is obviously from the second end 112b of the second end tube 11 2 of the lamp tube 11 2, thereby causing the brightness of the tube Π 2, please refer to the circuit diagram 3 of the optical module. It shows a back view in accordance with a first embodiment of the present invention. The backlight module 200 includes a backlight 2 1 0 and a reverse switch

Page 11 1284766 Case No. 93113375 Month 修正 Amendment V. Description of invention (4) Flow device 2 2 0. The backlight 2 1 0 includes a lamp 2 1 2 and a back plate 2 1 4 . The lamp 2 1 2 such as a Cold Cathode Fluorescent Lamp (CCFL). The back plate 21 4 is adjacent to the lamp tube 212 and electrically connected to the ground end. The backing plate 2 1 4 is made of, for example, aluminum. ❿ The inverter 2 2 0 includes a control unit 2 2 2 and a transformer 2 2 4 . The control unit 2 2 2 is for receiving the DC voltage D C and outputting the AC voltage A C . The transformer 2 2 4 includes a primary side coil 2 3 2 and a secondary side coil 2 3 4 . The primary side coil 2 3 2 is coupled between the control unit 2 2 2 and the ground for receiving the AC voltage A C . The primary side coil 2 3 4 senses the AC voltage AC of the primary side coil 2 3 2, and outputs a high voltage alternating current 丨t to the lamp tube 2丨2 to drive the lamp tube 2 i 2 to make it sufficiently bright and sufficiently uniform. Light. The first end 234 a and the second end 234 b of the secondary side coil 2 3 4 are electrically connected to the first end 212 a and the second end 2 1 2 b of the bulb 21 2 , respectively. Since the two ends of the secondary side coil 234 are electrically connected to the two ends of the lamp 2 1 2 ^, respectively, and are not electrically connected to the ground, the second side coil 234 and the back plate 11 4 are connected. Electrically isolated. This will cut off the leakage current loop, or increase the loop impedance of the leakage current, thereby reducing the leakage current and increasing the luminous efficiency of the lamp 2 1 ; In addition, the phenomenon that the leakage current effectively reduces the unevenness of the brightness of the lamp 2 2 1 2 can also be greatly improved. On the other hand, in order to allow the control unit 2 2 2 to accurately control the electric current flowing through the bulb 212 between the second end 2121 of the bulb 212 and the second end 234b of the secondary coil 234, The feedback unit 22 6 is electrically connected to output the feedback signal FB to the control unit 222. In this way, after receiving the DC voltage DC, the control unit 22 can output the AC voltage Ac according to the feedback signal FB.

Page 12 1284766

_ Case No. 93113375 _ Year, Month, Day _^|T V. Invention Description (5) — Effectively control the current flowing through the lamp 2 1 2 . Referring to Figure 4, there is shown a circuit diagram of a first feedback unit suitable for use in the first embodiment of the present invention. The feedback unit 426 includes a diode 26 〇 and an e-optical coupler 270. The photocoupler 27 0 includes an iight-emitting diode LED and a photo-electric crystal QA. Wherein, the LED is not grounded, but is electrically isolated from the photovoltaic transistor QA. Further, the light-emitting diode L E D is connected in parallel with the other diode 26 0 so that the alternating current driving current I d can flow in both the positive half cycle and the negative half cycle. When the driving current Id flows through the LED, the LEDs emit an optical signal, so that the photo-electric crystal QA can output the feedback signal FB according to the optical signal. Therefore, when the feedback unit 2 26 of FIG. 3 is the feedback unit 426 of FIG. 4 , the secondary side coil 234 and the back plate 21 4 can still be maintained in an electrically isolated state, and The control unit 2 2 2 can accurately control the current flowing through the lamp 2 1 2 by the feedback signal FB. Referring to Figure 5, there is shown a circuit diagram of a second feedback unit suitable for use in the first embodiment of the present invention. The feedback unit 52 6 includes a first optical coupler 280 and a second optical coupler 284. When the driving current I d flows through the LED 2, the LED 1 emits an optical signal, so that the photo transistor QB1 can output the feedback signal FBI according to the optical signal. When the driving current Id flows through the LED 2, the LED 2 emits an optical signal, so that the photo transistor QB2 can output the feedback signal FB2 according to the optical signal. After the feedback signal FBI is added to the feedback signal FB2, the feedback signal FB is output. Please refer to FIG. 6 , which shows the third implementation of the first implementation of the invention 1284766 _ case number 93113375_year revision _ V. Description of the invention (6) Circuit diagram of the feedback unit of the example. The feedback unit 62 6 includes a resistor RE and a transformer 209. The transformer 209 includes a primary side coil 2 9 2 and a secondary side coil 2 9 4 . When the driving current I d flows through the primary side coil 2 9 2 , the secondary side coil 294 senses the feedback signal F B according to the driving current I d . However, the feedback unit 2 26 is not limited as long as the feedback signal can be generated according to the driving current I d to the control unit 2 2 2, and the secondary side coil 234 and the back plate 2 1 4 can still be The state of being electrically isolated can be used as the feedback unit 2 26 of the embodiment. Embodiment 2 Referring to Figure 7, a circuit diagram of a backlight module in accordance with a second embodiment of the present invention is shown. The backlight module 300 includes a backlight 310 and a reverse converter 320. The main difference between the second embodiment and the first embodiment is that the inverter of the first embodiment drives the backlight in a unilateral driving manner, and in the second embodiment, the reverse commutation The device 3 2 0 drives the backlight 3 10 0 in a bilaterally driven manner. The inverter 3202 includes a first control unit 32, a second control unit 342, a first transformer 324, a second transformer 344, and a feedback unit 326. The first control unit 32 2 is configured to receive the DC voltage DC 1 and output an AC voltage input (: 1. The second control unit 342 is configured to receive the DC voltage 0〇2 and output the AC voltage AC2. The AC2 and the AC voltage AC1 are voltages of opposite polarities. Further, the first transformer 3 24 includes a primary side coil 3 3 2 and a secondary side coil 3 3 4 . The primary side coil 3 3 2 is electrically connected to the first control unit. 3 2 2 with

Page 14 修正 Amendment 1284766 93113375 V. INSTRUCTIONS (7) Between the ground terminals for receiving AC voltage AC 1. The secondary side coil 334 senses the alternating current AC 1 of the primary side coil 3 3 2 and outputs a high voltage alternating current It 1 to the first end 312a of the bulb 31 2 . The second transformer 3 44 includes a primary side coil 3 5 2 and a secondary side coil 3 5 4 . The primary side coil 3 5 2 is electrically connected between the second control unit 342 and the ground for receiving the alternating voltage ac2. The secondary side coil 354 senses the alternating voltage AC2 of the primary side coil 35 2 and outputs a high voltage alternating current It2 to the second end 312b of the bulb 31 2 . The first end 334a and the second end 334b of the secondary side coil 334 are electrically connected to the first end 31 2a of the lamp tube 31 2 and the second end 354 b of the secondary side coil 354, respectively, and the secondary side coil The first end of the 3 5 4 3 5 4 a is electrically connected to the second end 312b of the lamp tube 3丨2. Further, the feedback unit 3 26 is electrically connected between the second end 334b of the secondary side coil 3 3 4 and the second end 354b of the secondary side coil 354 to output the feedback signal FB to the first control. Unit 322 and second control unit 342. Thus, the second control unit 322 and the second control unit 342 are able to effectively control the magnitude of the current flowing through the lamp e 31 2 . The feedback unit 3 26 is, for example, the feedback unit 426 of FIG. 4, the feedback unit 526 of FIG. 5, or the feedback unit 626 of FIG. Due to the secondary side coil 334 and the secondary side coil 354, the secondary side coil 334 and the backing plate 314 are electrically isolated from each other by the ^-j coil 354 and the backing plate 314. Therefore, the circuit can be cut, or the loop impedance of the leakage current can be increased to achieve the reduction, and, like the first embodiment, the feedback unit 32 of the second embodiment (

1284766

1284766 Illustration of the simple description of the case number 93313375_^ Correction [Simple description of the drawing] Figure 1 shows the circuit diagram of the conventional backlight module; Figure 2 shows the equivalent circuit diagram of the backlight module according to Figure 1. FIG. 3 is a circuit diagram of a backlight module according to a first embodiment of the present invention; FIG. 4 is a circuit diagram of a first feedback unit applicable to the first embodiment of the present invention; A second circuit diagram of a feedback unit applicable to the first embodiment of the present invention; FIG. 6 is a circuit diagram of a third feedback unit applicable to the first embodiment of the present invention; and FIG. 7 is a diagram A circuit diagram of a backlight module according to a second embodiment of the present invention. Schematic description of the description 1 0 0, 2 0 0, 3 0 0: backlight module I 1 0, 2 1 0, 3 1 0: backlight 112, 212, 312: lamp tube 112a, 212a, 312a: lamp tube First end 112b, 212b, 312b: second end of lamp tube II 4, 2 1 4, 3 1 4 : back plate 1 2 0, 2 2 0, 3 2 0 : inverter inverter 1 2 2 2 2 : Control unit 1284766 Case No. 93113375 Year a Corrective diagram 124, 224 ^ 2 9 0 : Transformer 126> 226 ^ 426 ' 5 2 6 , 6 2 6 > 326 : Feedback unit 132' 232 &gt 2 92 > 332, 3 5 2 : primary side coils 134, 234, 2 94, 334 ' 354 : secondary side coils 234a, 334a, 354a: first ends 234b, 334b, 354b of secondary side coils: The second end of the secondary coil 2 6 0 : the diode 2 70 : the optical coupler 28 0 : the first optical coupler 284: the second optical coupler # 3 2 2 : the first control unit 324: the first transformer 342 : second control unit 344: second transformer

Page 18

Claims (1)

1284766 —---- Case No. 6. Patent Application Area 1. A backlight module comprising: a backlight, comprising: a light tube for emitting a light; and a back plate adjacent to the light tube, and Electrically connected to a ground for reflecting the light; and an inverter for driving the backlight, the inverter includes: a control unit for receiving the current a power source, and outputting a first parent power source, and a dust filter, comprising: a primary side coil electrically connected between the control unit and the ground terminal for receiving the first AC power source; a first-order side coil is configured to output a second alternating current power source to the first end of the light tube according to the first alternating current power source, wherein the first end of the 'secondary side coil and the second end end The first end and the second end of the light tube are electrically connected to each other; and a feedback unit is electrically connected between the second end of the backlight and the second end of the second side coil For outputting a feedback signal to the control unit, and causing the lamp to The backplanes are electrically isolated. 2. The backlight module of claim 1, wherein the feedback unit comprises an optical light combiner. The backlight module of claim 2, wherein the optical coupler comprises: a light emitting diode electrically connected to the second end of the back source Page 19 1284766 _ Case No. 93113375 Revision of the target _ 6. The patent application scope is not grounded between the second end of the secondary side coil; and an optoelectronic transistor is issued according to the illuminating diode The optical signal outputs a feedback signal to the control unit. 4. The backlight module of claim 1, wherein the lamp is a Cold Cathode Fluorescent Lamp (CCFL), . 5. as claimed in claim 1 The backlight module is characterized in that the back plate is a metal back plate. 6. The backlight module of claim 5, wherein the metal back plate is a back plate. 7. A backlight module, comprising: a backlight, comprising: a light tube, for emitting a light; and a back plate adjacent to the light tube, and electrically connected to a ground end, For reflecting the light; and an inverter for driving the backlight, the inverter includes: a first control unit for receiving a first DC power supply, and outputting a first AC power supply; a second control unit, configured to receive a second DC power source, and output a second AC power source, wherein the second AC power source and the first AC power source are opposite polarity power sources; The first transformer includes: a %, the secondary side coil is electrically connected to the first control Page 20 Case No. 93113375 曰 1284766 Amendment 6. Between the patent-scoped unit and the ground, for receiving the first AC power; and the first and second inverted coils are based on the first AC power output a second parent current source is connected to the first end of the lamp tube, wherein a first end of the first secondary side coil is electrically connected to the first end of the lamp tube; a second transformer includes a first primary side coil electrically connected between the second control unit and the ground end for receiving the second alternating current power source; and a second secondary side coil according to the second alternating current The power supply outputs a fourth alternating current power supply to a second end of the light tube, wherein a first end of the second secondary side coil is electrically connected to the second end of the light tube, the second second One second end of the side coil is electrically connected to one second end of the first secondary coil; and two: the unit 1 is electrically connected to the first fine of the first secondary side coil for the first time The second side of the circle is used to rotate a feedback signal to the first System control unit and the second unit, and so the electrical isolation between the lamp and the backing plate. The backlight module as described in claim 7 of the patent application includes an optical coupler. The backlight module coupler as described in claim 8 includes: - a body, which is electrically connected to the second end of the backlight and the second side coil Between the second end and not grounded; and an optoelectronic transistor, according to the LED, a feedback signal is sent to the first control unit and the second control unit. Children's drama Clause 21 I 1284766 Case No. 93113375 Issued Amendment VI. Patent Application Range 10. The backlight module of claim 7, wherein the lamp is a CCFL. 11. The backlight module of claim 7, wherein the back panel is a metal back panel. 12. The backlight module of claim 7, wherein the metal backplane is an SS backplane. ... ❿ Page 22