WO2012006803A1 - 背光模块及液晶显示器 - Google Patents

背光模块及液晶显示器 Download PDF

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Publication number
WO2012006803A1
WO2012006803A1 PCT/CN2010/076523 CN2010076523W WO2012006803A1 WO 2012006803 A1 WO2012006803 A1 WO 2012006803A1 CN 2010076523 W CN2010076523 W CN 2010076523W WO 2012006803 A1 WO2012006803 A1 WO 2012006803A1
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WO
WIPO (PCT)
Prior art keywords
component
switch
electrically connected
level
driving voltage
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/CN2010/076523
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English (en)
French (fr)
Inventor
贺成明
杨景元
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TCL China Star Optoelectronics Technology Co Ltd
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Shenzhen China Star Optoelectronics Technology Co Ltd
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Application filed by Shenzhen China Star Optoelectronics Technology Co Ltd filed Critical Shenzhen China Star Optoelectronics Technology Co Ltd
Priority to US12/996,342 priority Critical patent/US8912729B2/en
Publication of WO2012006803A1 publication Critical patent/WO2012006803A1/zh
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • H05B45/3725—Switched mode power supply [SMPS]
    • H05B45/38—Switched mode power supply [SMPS] using boost topology
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • H05B45/3725—Switched mode power supply [SMPS]
    • H05B45/39—Circuits containing inverter bridges
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Definitions

  • the present invention relates to a backlight module, and more particularly to a backlight module and a liquid crystal display using the same. Background technique
  • LCD monitors have become increasingly popular for a variety of electronic devices such as mobile phones, personal digital assistants (PDAs), digital cameras, computer screens or notebook screens.
  • PDAs personal digital assistants
  • the backlight unit is one of the key components of the liquid crystal display panel (LCD panel). Since the liquid crystal itself does not emit light, the function of the backlight module is to supply a sufficient light source with uniform brightness and uniformity. The simple and effective optical mechanism is converted into a high-brightness and uniform luminance surface light source to provide a backlight of the liquid crystal display panel.
  • LCD panels are now widely used in electronic products with potential for growth, such as monitors, notebook computers, digital cameras and projectors, especially for large-size panels such as notebook computers and LCD monitors, and therefore for backlight modules. Growth has also grown stronger.
  • the light emitting diode (LED) of the backlight module has the advantages of environmental protection and fast response due to mercury-free, and has become the backlight source of the LCD television in recent years. Mainstream. Most of the current LEDs are driven by Direct Current (DC). However, as LED lighting is becoming more prevalent, the use of communication (Alternative) Current, AC) mode drive LEDs are also beginning to prevail.
  • the advantage of using the AC to drive the LED is that the LED will only work half the time and the other half of the time during the entire circuit cycle, which can greatly reduce the heat generated by the LED, thereby increasing the life of the LED. Under ideal operating conditions, the AC mode drive LED must be connected to the LED with a current limiting resistor to limit the current flowing through the LED, but the voltage drop caused by the current flowing through the LED will reduce the conversion efficiency of the circuit.
  • an object of the present invention is to provide a backlight module including a DC/DC converter that generates a positive/negative level, and an AC voltage can be outputted at the output of the converter by sequentially switching the switches to drive the LEDs. Reduce the risk of LEDs being too inefficient due to the use of current limiting resistors and the potential for LEDs to burn out.
  • the invention provides a liquid crystal display comprising a power supply end and a liquid crystal display panel.
  • the power terminal is used to generate a supply voltage.
  • the liquid crystal display panel includes a liquid crystal layer for displaying an image.
  • the liquid crystal display further includes a converter and a light emitting device.
  • the converter is electrically connected to the power terminal, and includes a switch signal generator for generating a switch signal, wherein the converter is configured to convert the supply voltage to positive when the switch signal is at a first level a level driving voltage; or converting the supply voltage to a negative level driving voltage when the switching signal is at a second level, wherein the positive level driving voltage and the negative level driving voltage are alternately generated.
  • the illuminating device is used to The positive level driving voltage or the negative level driving voltage from the converter generates light.
  • the light emitting device may be an alternating current light emitting diode.
  • the light-emitting device comprises a first light-emitting unit, a second light-emitting unit, a third light-emitting unit, a fourth light-emitting unit and a fifth light-emitting unit, wherein the positive and negative ends of the first light-emitting unit are respectively connected a first node and a second node, wherein the positive and negative ends of the second light emitting unit are respectively connected to the second node and a third node, and the positive and negative ends of the third light emitting unit are respectively connected to The third node and a fourth node, the positive and negative ends of the fourth lighting unit are respectively connected to the fourth node and the second node, and the positive and negative ends of the fifth lighting unit are respectively connected And the third node and the first node.
  • the first, second, third, fourth and fifth light emitting units are light emitting diodes.
  • the converter comprises a capacitor component, a first switch component, a second switch component, a first inductor component, a second inductor component, a third switch component, a first diode and a second diode tube.
  • the capacitor assembly is connected in parallel to the light emitting device.
  • the switch component is electrically connected to the power terminal, and is configured to be turned on when receiving the switch signal at the first level.
  • the switch component is electrically connected to the power terminal, and is configured to be turned on when receiving the switch signal at the first level.
  • the inductor component is electrically connected to the first switch component.
  • the second inductive component is electrically connected to the power terminal, the second switch component, and the capacitor component.
  • the third switch component is electrically connected to the first and second inductor components, the power terminal, and the capacitor component, and is configured to be turned on when the switch signal is at the second level.
  • the first diode is electrically connected to the capacitor component, the first inductor component, and the third switch component.
  • the second diode is electrically connected to the capacitor component, the second inductor component, the first diode, and the second switch component.
  • the switching signal generator further comprises an inverter for inverting the first switching signal to generate the second switching signal.
  • the present invention utilizes a DC/DC converter which can alternately generate positive/negative levels, and can output an AC voltage at the output end by sequentially switching the switches to drive the LEDs to reduce the LEDs due to the use of current limiting resistors.
  • the resulting circuit is too inefficient and the risk of LEDs being burned out.
  • Figure 1 is a schematic illustration of a liquid crystal display in accordance with a preferred embodiment of the present invention.
  • FIG. 2 is a schematic diagram showing when the switch component is turned on by the first switch signal, so that the converter outputs a positive level driving voltage.
  • FIG. 3 is a schematic diagram showing when the switch component is turned on by the second switch signal, causing the converter to output a negative level driving voltage.
  • Figure 4 is a configuration diagram of another embodiment of the light-emitting device of Figure 1 of the present invention. detailed description
  • FIG. 1 is a schematic diagram of a liquid crystal display 20 in accordance with a preferred embodiment of the present invention.
  • the liquid crystal display 20 includes a power supply terminal 21, a liquid crystal display panel 30, and a backlight module 10.
  • the backlight module 10 generates light required for the liquid crystal display panel 30 using the voltage supplied from the power supply terminal 21.
  • the backlight module 10 includes a light emitting device 22 and a converter 24.
  • the power terminal 21 is used to provide a DC supply voltage V DC .
  • the liquid crystal display panel 30 includes a liquid crystal layer composed of liquid crystal molecules, and liquid crystal molecules are generated according to respective image data. Different arrangement angles are used to thereby adjust the light emitted by the backlight module 10 to present images of different gray levels.
  • the light-emitting device 22 includes a plurality of alternating current light-emitting diodes 33, and the alternating current light-emitting diodes 33 are driven to emit light by alternating current.
  • One end of the light-emitting device 22 is electrically connected to the converter 24, and the other end is electrically connected to a voltage terminal (grounded in FIG. 1) for generating light according to the driving voltage sent by the converter 24.
  • the converter 24 is for converting the DC voltage (12 V) of the power supply terminal 21 into a high DC voltage which alternately outputs a positive/negative level.
  • the high DC voltage which alternately outputs the positive/negative level is a simulation of an AC voltage.
  • the converter 24 includes a switch signal generator 40, a capacitor component C, a first switch component S1, a second switch component S2, a third switch component S3, a first inductor component L1, a second inductor component L2, and a first diode D1. And a second diode D2.
  • the capacitive component C is connected in parallel to the illumination device.
  • the first switch component S1 is electrically connected to the power terminal 21 .
  • the first inductive component L1 is electrically connected to the first switch component S1.
  • the second inductor component L2 is electrically connected to the power terminal 21, the second switch component S2, and the capacitor component C.
  • the third switch component S3 is electrically connected to the second inductor component L2, the power terminal 21, and the second diode D2.
  • the first diode D1 is electrically connected to the capacitor component C, the first inductor component L1, and the second switch component S2.
  • the second diode D2 is electrically connected to the capacitor component C, the second inductor component L2, and the third switch component S3.
  • the switch polarity of the first switch component S1 and the second switch component S2 is the same as that of the third switch component S3.
  • the switch signal generator 40 is used to generate the first switch signal V C1 when the first switch signal V After the C1 is input to the inverter 41, a second switching signal V C2 that is inverted from the first switching signal V C1 is generated.
  • the first switch component S1, the second switch component S2 may be NMOS transistors and the third switch component S3 is a PMOS transistor.
  • the switches of the first switch component S1, the second switch component S2, and the third switch component S3 are all controlled by the same switch signal V C1 .
  • the switch signal ⁇ is at a high level, the first switch component S1, the first The second switch assembly S2 will be turned on and the third switch assembly S3 will be turned off.
  • the switch signal ⁇ is at a low level
  • the first switch component S1 and the second switch component S2 are turned off, and the third switch component S3 is turned on.
  • the inductive components L1, L2 act as energy storage components and store electrical energy as current passes.
  • FIG. 2 is a schematic diagram showing when the switch components S1, S2 are turned on by the first switch signal V C1 , so that the converter 24 outputs a positive level driving voltage
  • FIG. 3 illustrates the switch component S3
  • the second switching signal V C2 is turned on, causing the converter 24 to output a schematic diagram of the negative level driving voltage.
  • the switch components S1, S2 are turned on and the switch component S3 is turned off, so that the inductor component L1, the diode D1, and the light emitting device 22 form a The current loop, at which point the illumination device 22 receives the drive voltage (i.e., the level at the output of diode D1).
  • the light-emitting device 22 emits light due to the driving voltage Vo of a positive level.
  • the switch components S1, S2 are turned off and the switch component S3 is turned on, so that the inductor component L2 and the illuminating device 22 form a current loop.
  • the capacitance level C of the capacitance element C is changed to a negative level due to a change in the direction of the current.
  • the output of the converter 24 also alternately outputs positive/negative levels with the frequencies of the first switching signal ⁇ and the second switching signal V C2 .
  • the driving voltage is applied to the light emitting device 22.
  • the converter 24 is a DC/DC converter that alternately outputs positive/negative levels, and an alternating voltage can be outputted at the output by sequential switching of the switches.
  • FIG. 4 is a structural diagram of another embodiment of the light-emitting device 22 of FIG.
  • the light emitting device 22 includes a first light emitting unit 22a, a second light emitting unit 22b, a third light emitting unit 22c, a fourth light emitting unit 22d, and a fifth light emitting unit 22e,
  • the positive and negative ends of the first light emitting unit 22a are respectively connected to the first node N1 and the second node N2, and the positive and negative ends of the second light emitting unit 22b are respectively connected to the second node N2 and the third node N3, and the third light emitting unit
  • the positive and negative ends of 22c are respectively connected to the third node N3 and the fourth node N4.
  • the positive and negative ends of the fourth light emitting unit 22d are respectively connected to the fourth node N4 and the second node N2, and the positive and negative ends of the fifth light emitting unit 22e are respectively connected to the third node N3 and the first node N1.
  • the first, second, third, fourth, and fifth light emitting units 22a-22e are composed of a single light emitting diode (LED) 32 or a plurality of light emitting diodes connected in series.
  • the light-emitting units 22d, 22b, 22e are driven by the forward bias, but the light-emitting units 22a, 22c are reverse-biased and are not driven. . Therefore, at any time, three light-emitting units are driven to emit light, so that there is no visually uncomfortable discomfort. More importantly, because the converter 24 of the present invention does not use a current limiting resistor and does not allow the LED to remain in a state of being driven to emit light, it can improve circuit efficiency and reduce the risk of LED burning.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Circuit Arrangement For Electric Light Sources In General (AREA)
  • Liquid Crystal Display Device Control (AREA)

Abstract

一种背光模块（10）及液晶显示器（20），背光模块（10）包括电源端（21），用于产生供应电压；转换器（24），与电源端（21）电连接，包括一个开关信号产生器（40），用于产生开关信号，当开关信号处于第一电平时，转换器（24）将供应电压转换成正电平驱动电压，当开关信号处于第二电平时，转换器（24）将供应电压转换成负电平驱动电压，正电平驱动电压和负电平驱动电压交替产生；发光装置（22），与转换器（24）电连接，用于依据转换器（24）传送的正电平驱动电压或负电平驱动电压产生光。

Description

背光模块及液晶显示器
技术领域
本发明是涉及一种背光模块， 尤指一种背光模块以及应用该背光模块的 液晶显示器。 背景技术
功能先进的显示器渐成为现今消费电子产品的重要特色， 其中液晶显示 器已经逐渐成为各种电子设备如行动电话、 个人数字助理 (PDA)、 数字相机、 计算机屏幕或笔记型计算机屏幕所广泛应用具有高分辨率彩色屏幕的显示 器。
背光模块 (Back Light Unit)为液晶显示器面板 (Liquid Crystal Display Panel, LCD panel)的关键零组件之一， 由于液晶本身不发光， 背光模块的功能即在 于供应充足的亮度与分布均匀的光源， 透过简洁有效光机构转化成高亮度且 均一辉度的面光源， 以提供液晶显示器面板背光光源。 液晶显示器面板现已 广泛应用于监视器、 笔记本计算机、 数字相机及投影机等具成长潜力的电子 产品， 尤以笔记型计算机及 LCD监视器等大尺寸用面板需求最大， 也因此对 于背光模块需求成长也日趋强烈。
目前背光模块所使用的发光源除了冷阴极荧光灯管之外， 发光二极管 (Light emitting diode, LED)由于因无汞而具有环保及响应速度快等优点， 近 几年来已成为 LCD电视背光灯源的主流。 现行 LED大都是以直流 （Direct Current, DC)方式驱动， 然而随着 LED照明日渐盛行， 利用交流（Alternative Current, AC) 方式驱动 LED也逐渐开始盛行。 利用交流方式驱动 LED的好处 在于， 在整个电路周期中 LED只会有一半的时间在工作， 另一半的时间则在 休息， 如此可大大降低 LED所产生热的问题， 进而提高 LED的使用寿命。 理 想操作条件下， 交流方式驱动 LED必须以限流电阻串接于 LED上以限制流经 LED的电流， 但电流流经 LED所造成的电压降， 却会降低电路的转换效率。
倘若减少限流电阻的使用， 将使 LED容易被烧毁。 由于交流电压波动的 幅度。 随地区和环境不同而有所变化， 且 LED 的正向电压 (VF)也随温度和制 造厂商的技术有飘移。 因此刻意减少限流电阻的使用或降低电阻值以提高效 率， 将造成 LED烧毁或亮度不足的问题。 发明内容
因此本发明的目的是提供 种背光模块， 包含有产生正 /负电平的 DC/DC 转换器 (Converter)，通过开关的顺序切换即可在转换器输出端输出一交流电压 藉此驱动 LED, 以减少 LED因使用限流电阻造成的电路效率过低及 LED可能 烧毁的风险。
本发明提供一种液晶显示器， 其包含电源端及液晶显示面板。所述电源 端用来产生供应电压。 所述液晶显示面板包含液晶层， 用来显示影像。 所述 液晶显示器另包含转换器和发光装置。 所述转换器电性连接于所述电源端， 其包含一开关信号产生器， 用来产生开关信号， 所述转换器用来於所述开关 信号处于第一电平时， 将所述供应电压转换成正电平驱动电压； 或是於所述 开关信号处于第二电平时， 将所述供应电压转换成负电平驱动电压， 所述正 电平驱动电压及所述负电平驱动电压是交替产生。 所述发光装置用来依据所 述转换器传来的所述正电平驱动电压或是所述负电平驱动电压产生光线。 依据本发明的实施例， 所述发光装置可以为交流发光二极管。
依据本发明的实施例， 所述发光装置包含第一发光单元、第二发光单元、 第三发光单元、 第四发光单元和第五发光单元， 所述第一发光单元的正、 负 端分别连接于一第一节点与一第二节点， 所述第二发光单元的正、 负端分别 连接于所述第二节点与一第三节点， 所述第三发光单元的正、 负端分别连接 于所述第三节点与一第四节点， 所述第四发光单元的正、 负端分别连接于所 述第四节点与所述第二节点， 所述第五发光单元的正、 负端分别连接于所述 第三节点与所述第一节点。 且所述第一、 第二、 第三、 第四和第五发光单元 是发光二极管。
依据本发明的实施例， 所述转换器包含电容组件、 第一开关组件、 第二 开关组件、 第一电感组件、 第二电感组件、 第三开关组件、 第一二极管和第 二二极管。 所述电容组件， 并联于所述发光装置。 所述开关组件电性连接于 所述电源端， 用来于接收所述开关信号处于所述第一电平时导通。 所述开关 组件电性连接于所述电源端， 用来于接收所述开关信号处于所述第一电平时 导通。 所述电感組件电性连接于所述第一开关组件。 所述第二电感组件电性 连接于所述电源端、 所述第二开关组件及所述电容组件。 所述第三开关组件 电性连接于所述第一、 第二电感组件、 所述电源端和所述电容组件， 用来接 收所述开关信号处于所述第二电平时导通。 所述第一二极管， 电性连接于所 述电容组件、 所述第一电感组件和所述第三开关组件。 所述第二二极管电性 连接于所述电容组件、 所述第二电感组件、 所述第一二极管和所述第二开关 组件。 依据本发明的实施例， 所述开关信号产生器另包含一反相器， 用来反相 所述第一开关信号以产生所述第二开关信号。
相较于先前技术， 本发明利用可交替产生正 /负电平的 DC/DC 转换器， 通过开关的顺序切换即可在输出端输出一交流电压藉此驱动 LED, 以减少 LED因使用限流电阻造成的电路效率过低及 LED可能烧毁的风险。
为让本发明的上述内容能更明显易懂， 下文特举一较佳实施例， 并配合 所附图式， 作详细说明如下： 附图说明
图 1是本发明较佳实施例的液晶显示器的示意图。
图 2绘示当开关组件因第一开关信号导通， 使得转换器输出正电平驱动 电压的示意图。
图 3绘示当开关组件因第二开关信号导通， 使得转换器输出负电平驱动 电压的示意图。
图 4是本发明图 1的发光装置另一实施例的构造图。 具体实施方式
请参阅图 1， 图 1是本发明较佳实施例的液晶显示器 20的示意图。 液晶 显示器 20包含电源端 21、 液晶显示面板 30及背光模块 10。 背光模块 10利 用电源端 21提供的电压产生液晶显示面板 30所需的光线。背光模块 10包含 发光装置 22及转换器 24。 电源端 21用来提供直流供应电压 VDC。 液晶显示 面板 30包含由液晶分子构成的液晶层，液晶分子会依据各个影像数据而产生 不同的排列角度，藉此调整前述背光模块 10发出的光线以呈现不同的灰阶的 影像。 发光装置 22包含若干个交流发光二极管 33， 交流发光二极管 33是以 交流电驱动发光。 发光装置 22的一端电性连接于转换器 24， 另一端电性连 接于一电压端 (在图 1中是接地端)， 用来依据转换器 24所送出的驱动电压产 生光线。
请继续参阅图 1。 转换器 24是用来将电源端 21的直流电压 (12V)转换成 交替输出正 /负电平的高直流电压，实际上，交替输出正 /负电平的高直流电压 就是仿真一交流电压。 转换器 24包含开关信号产生器 40、 电容组件 C、 第 一开关组件 Sl、 第二开关组件 S2、 第三开关组件 S3、 第一电感组件 Ll、 第 二电感组件 L2、 第一二极管 D1和第二二极管 D2。 所述电容组件 C并联于 所述发光装置。 所述第一开关组件 S1 电性连接于电源端 21。 第一电感组件 L1电性连接于第一开关组件 Sl。第二电感组件 L2电性连接于电源端 21、第 二开关组件 S2及电容组件 C。第三开关组件 S3电性连接于第二电感组件 L2、 电源端 21和第二二极管 D2。第一二极管 D1电性连接于电容组件 C、第一电 感组件 L1和第二开关组件 S2。第二二极管 D2电性连接于电容组件 C、第二 电感组件 L2和第三开关组件 S3。 第一开关组件 S1和第二开关组件 S2的开 关极性相同於第三开关组件 S3 , 在一实施例中， 开关信号产生器 40用来产 生第一开关信号 VC1， 当第一开关信号 VC1输入反相器 41后会产生与第一开 关信号 VC1反相的第二开关信号 VC2。 在另一实施例中， 第一开关组件 Sl、 第二开关组件 S2可以是 NMOS晶体管而第三开关组件 S3则是 PMOS晶体 管。第一开关组件 Sl、第二开关组件 S2和第三开关组件 S3的开关都是用同 一开关信号 VC1控制。 当开关信号 ^处于时高电平， 第一开关组件 Sl、 第 二开关组件 S2会开启， 而第三开关组件 S3则会关闭。 相反的， 当开关信号 ^处于时低电平， 第一开关组件 Sl、第二开关组件 S2会關閉， 而第三开关 组件 S3则会开启。 电感组件 Ll、 L2作为储能组件， 在电流通过时会储存电 能。
请参考图 2和图 3， 图 2绘示当开关组件 Sl、 S2因第一开关信号 VC1导 通， 使得转换器 24输出正电平驱动电压的示意图， 图 3绘示当开关组件 S3 因第二开关信号 VC2导通， 使得转换器 24输出负电平驱动电压的示意图。 当 第一开关信号 VC1处于高电平而第二开关信号 ∞处于低电平时， 开关组件 Sl、 S2会导通且开关组件 S3会关闭， 使得电感组件 Ll、 二极管 D1和发光 装置 22形成一电流回路， 此时发光装置 22会接收到驱动电压 (也就是二极管 D1输出端的电平)。 发光装置 22因为正电平的驱动电压 Vo而发出光线。 当 第一开关信号 VC1处于低电平而第二开关信号 ∞处于高电平时， 开关组件 Sl、 S2会关闭且开关组件 S3会导通， 使得电感组件 L2和发光装置 22形成 一电流回路，此时电容组件 C因电流方向的变化使得输出至发光装置 22的驱 动电压 Vo变成负电平。因为第一开关信号 ^和第二开关信号 ∞是高频率 方波， 所以转换器 24的输出也会随着第一开关信号 ^和第二开关信号 VC2 的频率交替地输出正 /负电平的驱动电压予发光装置 22。 换句话说， 转换器 24是交替地输出正 /负电平的 DC/DC 转换器， 通过开关的顺序切换即可在输 出端输出一交流电压。
请参照图 4， 图 4是本发明图 1的发光装置 22另一实施例的构造图。 与 交流发光二极管 33不同的地方在于，发光装置 22包含第一发光单元 22a、第 二发光单元 22b、第三发光单元 22c、第四发光单元 22d和第五发光单元 22e， 第一发光单元 22a的正、 负端分别连接于第一节点 N1与第二节点 N2， 第二 发光单元 22b的正、 负端分别连接于第二节点 N2与第三节点 N3 , 第三发光 单元 22c的正、 负端分别连接于第三节点 N3与第四节点 N4。 第四发光单元 22d的正、 负端分别连接于第四节点 N4与第二节点 N2, 第五发光单元 22e 的正、 负端分别连接于第三节点 N3与第一节点 Nl。 且所述第一、 第二、 第 三、 第四和第五发光单元 22a-22e是单一发光二极管 (Light Emitting Diode, LED)32或是若干个串联的发光二极管组成。 当输入发光装置 22的驱动电压 是正电平时，发光单元 22a、 22b、 22c是顺向偏压 (forward bias)而被驱动发光， 但发光单元 22d、 22e是逆向偏压故不被驱动。 相反的， 当输入发光装置 22 的驱动电压是负电平时， 发光单元 22d、 22b, 22e是顺向偏压 (forward bias) 而被驱动发光， 但发光单元 22a、 22c是逆向偏压故不被驱动。 因此， 随时都 有三个发光单元被驱动而发光， 因此视觉上不会有忽明忽暗的不适感。 更重 要的， 因为本发明转换器 24没有使用限流电阻而且也没有让 LED持续保持 在被驱动而发光的状态，因此可以提升电路效率及减少 LED可能烧毁的风险。
综上所述， 虽然本发明已以较佳实施例揭露如上， 但此较佳实施例并非 用以限制本发明， 本领域的普通技术人员， 在不脱离本发明的精神和范围内， 均可作各种更动与润饰，因此本发明的保护范围以权利要求界定的范围为准。

Claims

权 利 要 求
1. 一种背光模块， 其包含： 一电源端， 用来产生一供应电压； 其特征在于: 所述背光模块另包含：
一转换器， 电性连接于所述电源端， 其包含一开关信号产生器， 用来产 生开关信号， 所述转换器用来於所述开关信号处于第一电平时， 将 所述供应电压转换成正电平驱动电压； 或是於接收所述开关信号处 于第二电平时， 将所述供应电压转换成负电平驱动电压， 所述正电 平驱动电压及所述负电平驱动电压是交替产生； 及
一发光装置， 电性连接于所述转换器，用来依据所述转换器传来的所述 正电平驱动电压或是所述负电平驱动电压产生光线。
2. 根据权利要求 1所述的背光模块， 其特征在于： 所述发光装置包含第一 发光单元、 第二发光单元、 第三发光单元、 第四发光单元和第五发光单 元，所述第一发光单元的正、负端分别连接于一第一节点与一第二节点， 所述第二发光单元的正、 负端分别连接于所述第二节点与一第三节点， 所述第三发光单元的正、 负端分别连接于所述第三节点与一第四节点所 述， 所述第四发光单元的正、 负端分别连接于所述第四节点与所述第二 节点， 所述第五发光单元的正、 负端分别连接于所述第三节点与所述第 一节点。
3. 根据权利要求 2所述的背光模块， 其特征在于： 所述第一、 第二、 第三、 第四和第五发光单元分别是单一发光二极管或是若干个串联的发光二极 管组成。
4. 根据权利要求 1所述的背光模块， 其特征在于： 所述转换器包含： 一电容组件， 并联于所述发光装置；
一第一开关组件， 电性连接于所述电源端， 用来于接收所述开关信号处 于所述第一电平时导通；
一第二开关组件， 电性连接于所述电源端， 用来于接收所述开关信号处 于所述第一电平时导通；
一第一电感组件， 电性连接于所述第一开关组件；
一第二电感组件， 电性连接于所述电源端、 所述第二开关组件及所述电 容组件；
一第三开关组件， 电性连接于所述第二电感组件和所述电源端， 用来接 收所述开关信号处于所述第二电平时导通；
一第一二极管， 电性连接于所述电容组件、 所述第一电感组件和所述第 二开关组件； 及
一第二二极管， 电性连接于所述电容组件、 所述第二电感组件、 所述第 一二极管和所述第三开关组件。
5. 根据权利要求 1所述的背光模块， 其特征在于： 所述开关信号产生器另 包含一反相器， 用来反相所述开关信号； 所述第一开关组件、 第二开关 组件与第三开关组件的开关极性相同。
6. 根据权利要求 1所述的背光模块， 其特征在于： 所述第一开关组件和所 述第二开关组件的开关极性相反于所述第三开关组件的开关极性， 但所 述第一开关组件、 所述第二开关组件和所述第三开关组件是用同一开关 信号控制。
7. 根据权利要求 1所述的背光模块， 其特征在于， 所述发光装置为交流发
8. 一种液晶显示器， 其包含一电源端及一液晶显示面板， 所述电源端用来 产生一供应电压， 所述液晶显示面板包含一液晶层， 用来显示影像； 其 特征在于： 所述液晶显示器另包含：
一转换器， 电性连接于所述电源端， 其包含一开关信号产生器， 用来产 生开关信号， 所述转换器用来於所述开关信号处于第一电平时， 将 所述供应电压转换成正电平驱动电压； 或是於接收所述开关信号处 于第二电平时， 将所述供应电压转换成负电平驱动电压， 所述正电 平驱动电压及所述负电平驱动电压是交替产生； 及
一发光装置， 电性连接于所述转换器， 用来依据所述转换器传来的所述 正电平驱动电压或是所述负电平驱动电压产生光线。
9. 根据权利要求 8所述的液晶显示器， 其特征在于： 所述转换器包含： 一电容组件， 并联于所述发光装置；
一第一开关组件， 电性连接于所述电源端， 用来于接收所述开关信号处 于所述第一电平时导通；
一第二开关组件， 电性连接于所述电源端， 用来于接收所述开关信号处 于所述第一电平时导通；
一第一电感组件， 电性连接于所述第一开关组件；
一第二电感组件， 电性连接于所述电源端、 所述第二开关组件及所述电 容组件；
一第三开关组件， 电性连接于所述第二电感组件和所述电源端， 用来接 收所述开关信号处于所述第二电平时导通；
一第一二极管， 电性连接于所述电容组件、 所述第一电感组件和所述第 二开关组件； 及
一第二二极管， 电性连接于所述电容组件、 所述第二电感组件、 所述第 一二极管和所述第三开关组件。
.根据权利要求 8所述的液晶显示器， 其特征在于： 所述开关信号产生器 另包含一反相器， 用来反相所述开关信号； 所述第一开关组件、 第二开 关组件与第三开关组件的开关极性相同。
.根据权利要求 8所述的液晶显示器， 其特征在于： 所述第一开关组件和 所述第二开关组件的开关极性相反于所述第三开关组件的开关极性， 但 所述第一开关组件、 所述第二开关组件和所述第三开关组件是用同一开 关信号控制。
.根据权利要求 8所述的液晶显示器， 其特征在于， 所述发光装置为交流
PCT/CN2010/076523 2010-07-12 2010-09-01 背光模块及液晶显示器 Ceased WO2012006803A1 (zh)

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