1337731 099年10月27日 、發明說明： 【發明所屬之技術領域】 [0001] 本發明係關於一種背光控制電路及其控制方法。 【先前技術】 [0002] • 液晶顯示器具有輕薄，低耗電及輻射少等特點，並被廣 ’乏用於監視器、液晶電視、行動電話及便携式電腦等電 子設備。由於液晶顯示器中之液晶分子本身並不發光， 因此液晶顯示器需借助一背光模組發光來實現圖像顯示 。背光模組中通常採用冷陰極射線管（c〇ld cath〇de fluorescent lamp’ CCLF)或發光二極體作為其發光之 光源。 [0003] 採用冷陰極射線管作為光源時，由於冷陰極射線管需高 壓父/’IL電壓來驅動，故需設計專用之背光控制電路，將 直流電壓轉化為交流電壓以驅動該冷陰極射線管。 [0004] • 請參閱圖1，係一種先前技術背光控制電路之示意圖。該 背光控制電路100包括一脈寬調變積體電路（pulse Width Modulation，PWM)120、一頻率設定電路 130' 一反相電路（Inverter)140及一背光燈150。該背光燈 150係一冷陰極射線管。該脈寬調變積體電路12〇之型號 為OZ9910 。 [0005] s玄脈寬調變積體電路120包括一頻率設定端121及一電源 端122。s玄頻率設定電路130包括一電阻132及一電容131 。該頻率設定端1 21經由該電容1 31接地。該電阻1 32連 接於該頻率設定端121與該電源端122之間。 096120807 表單編號删1 第3頁/共丨7頁 0993387248-0 1337731 [0006] [0007] [0008] [0009] [0010] [0011] 096120807 099年10月27日 該脈寬調變積體電路120正常工作時產生一脈衝訊號至該 反相電路140，該反相電路140根據該脈衝訊號將一直流 電壓轉換為一交流電壓用於驅動該背光燈150。該脈衝訊 號之頻率由該電阻132及電容131之大小決定，該交流電 壓之頻率與該脈衝訊號之頻率一致。 由上述可知，該背光燈150之工作頻率（即該交流電壓之 頻率）係由該脈衝訊號之頻率決定，其間接取決於該電阻 1 3 2及電容1 31。該脈衝訊號之頻率與該電阻1 3 2及電容 131之關係式如下：_ 9.35xlO5x RCT 厂為該脈衝訊號之頻率，單位為kHZ ;op RcT 為該電阻132之阻值，單位為kS7 ; 為該電容131 之容量，單位為PF。 對於不同尺寸的冷陰極射線管，其最佳卫錢率不同， 因此’應用該脈宽調變積體電路12叫，根據其所驅動的 冷陰極射線管之尺寸，對應設定該電阻132之阻值及電容 131之容量。1337731 October 27, 1999, invention: [Technical Field] [0001] The present invention relates to a backlight control circuit and a control method therefor. [Prior Art] [0002] • Liquid crystal displays are characterized by being thin and light, low in power consumption and low in radiation, and are widely used in electronic devices such as monitors, LCD TVs, mobile phones, and portable computers. Since the liquid crystal molecules in the liquid crystal display do not emit light by themselves, the liquid crystal display needs to be illuminated by a backlight module to realize image display. A backlight cathode module (c〇ld cath〇de fluorescent lamp' CCLF) or a light-emitting diode is generally used as a light source for its illumination. [0003] When a cold cathode ray tube is used as a light source, since the cold cathode ray tube needs a high voltage parent/'IL voltage to drive, it is necessary to design a dedicated backlight control circuit to convert the direct current voltage into an alternating voltage to drive the cold cathode ray tube. . [0004] • Referring to FIG. 1, a schematic diagram of a prior art backlight control circuit. The backlight control circuit 100 includes a pulse width modulation circuit (PWM) 120, a frequency setting circuit 130', an inverter 140, and a backlight 150. The backlight 150 is a cold cathode ray tube. The pulse width modulation integrated circuit 12 is modeled as OZ9910. [0005] The sinusoidal wide variable transformer circuit 120 includes a frequency setting terminal 121 and a power terminal 122. The sinusoidal frequency setting circuit 130 includes a resistor 132 and a capacitor 131. The frequency setting terminal 1 21 is grounded via the capacitor 1 31. The resistor 1 32 is connected between the frequency setting terminal 121 and the power terminal 122. 096120807 Form number deletion 1 Page 3 / Total 7 page 0993387248-0 1337731 [0006] [0007] [0009] [0010] [0011] 096120807 October 27, 2008, the pulse width modulation integrated circuit When the 120 is in normal operation, a pulse signal is generated to the inverter circuit 140. The inverter circuit 140 converts the DC voltage into an AC voltage according to the pulse signal for driving the backlight 150. The frequency of the pulse signal is determined by the size of the resistor 132 and the capacitor 131. The frequency of the alternating voltage is consistent with the frequency of the pulse signal. As can be seen from the above, the operating frequency of the backlight 150 (i.e., the frequency of the alternating voltage) is determined by the frequency of the pulse signal, which is indirectly dependent on the resistor 1 3 2 and the capacitor 1 31. The relationship between the frequency of the pulse signal and the resistance 1 3 2 and the capacitance 131 is as follows: _ 9.35xlO5x The RCT factory is the frequency of the pulse signal, and the unit is kHZ; op RcT is the resistance value of the resistor 132, and the unit is kS7; The capacity of the capacitor 131 is in PF. For different sizes of cold cathode ray tubes, the optimal money-saving rate is different, so the application of the pulse width modulation integrated circuit 12 is called, according to the size of the cold cathode ray tube driven by it, correspondingly setting the resistance of the resistor 132 Value and capacity of capacitor 131.
f〇P 其中f〇P where
准由於4工作頻率設定後不易更改使得該背光控制 電路1GG僅適用—種尺寸的冷陰極射線管，如果驅動其他 1號的燈管’射能使冷陰極㈣ 表單編號A0101 ^ ^ 1 0993387248-0 1,337731 099年10月27日俊正替换頁 作頻率，發光效率較低。 【發明内容】 [0012] 有鑑於此，提供一種發光效率較高之背光控制電路實為 必要。 [0013] 提供一種發光效率較高之背光控制電路之控制方法亦為 必要。The backlight control circuit 1GG is only applicable to the cold cathode ray tube of the same size because the 4 working frequency is not easily changed. If the other No. 1 tube is driven, the cold cathode (4) form number A0101 ^ ^ 1 0993387248-0 1,337731 On October 27, 099, Jun Zheng replaced the page as the frequency, and the luminous efficiency was low. SUMMARY OF THE INVENTION [0012] In view of the above, it is necessary to provide a backlight control circuit with high luminous efficiency. [0013] It is also necessary to provide a control method of a backlight control circuit with high luminous efficiency.
[0014] 一種背光控制電路，其包括一背光燈、一反相電路、一 脈寬調變積體電路、一燈管識別電路及一頻率調整電路 ，該頻率調整電路包括一查詢表，該查詢表存儲複數燈 管類型及代表該類型燈管之最佳工作頻率之指令；其中 ，該脈寬調變積體電路產生一脈衝訊號至該反相電路， 該反相電路根據該脈衝訊號將一直流電壓轉換為一交流 電壓驅動該背光燈，該燈管識別電路識別該背光燈之燈 管類型，該查詢表根據該燈管類型查詢出該類型燈管對 應之最佳工作頻率之指令，該頻率調整電路根據該燈管 類型對應之最佳工作頻率之指令調整該脈寬調變積體電 路產生之脈衝訊號之頻率，從而該反相電路調整該交流 電壓之頻率。 [0015] —種背光控制電路之控制方法，該背光控制電路包括一 背光燈，該控制方法包括如下步驟： [0016] (a)提供一交流電壓驅動該背光燈； [0017] (b)識別該背光燈之燈管類型；及 [0018] (C)查詢出該類型燈管對應之最佳工作頻率之指令，根據 該燈管類型對應之最佳工作頻率之指令調整該交流電壓 096120807 表單編號 A0101 第 5 頁/共 17 頁 0993387248-0 1337731 099年10月27日修正替換頁 之頻率。 [0019] 相較於先前技術，該背光控制電路及其控制方法中，藉 由識別該背光燈之燈管類型及根據燈管類型調整驅動該 背光燈之交流電壓之頻率，使該背光燈工作在最佳工作 頻率，發光效率較高。 【實施方式】[0014] A backlight control circuit includes a backlight, an inverter circuit, a pulse width modulation integrated circuit, a lamp identification circuit, and a frequency adjustment circuit, the frequency adjustment circuit includes a lookup table, the query The table stores a plurality of lamp types and instructions for representing an optimum operating frequency of the lamp; wherein the pulse width modulation integrated circuit generates a pulse signal to the inverter circuit, and the inverter circuit converts the pulse signal according to the pulse signal The DC voltage is converted into an AC voltage to drive the backlight, the lamp identification circuit identifies the type of the lamp of the backlight, and the lookup table queries an instruction corresponding to the optimal working frequency of the lamp according to the type of the lamp, The frequency adjustment circuit adjusts the frequency of the pulse signal generated by the pulse width modulation integrated circuit according to the instruction of the optimal operating frequency corresponding to the lamp type, so that the inverter circuit adjusts the frequency of the alternating voltage. [0015] A control method of a backlight control circuit, the backlight control circuit comprising a backlight, the control method comprising the following steps: [0016] (a) providing an alternating voltage to drive the backlight; [0017] (b) identifying The lamp type of the backlight; and [0018] (C) querying the instruction of the optimal working frequency corresponding to the lamp of the type, and adjusting the AC voltage 096120807 form number according to the instruction of the optimal working frequency corresponding to the lamp type A0101 Page 5 of 17 0993387248-0 1337731 The frequency of the replacement page was revised on October 27, 099. [0019] Compared with the prior art, in the backlight control circuit and the control method thereof, the backlight is operated by identifying the type of the lamp of the backlight and adjusting the frequency of the alternating voltage driving the backlight according to the type of the lamp. At the optimum operating frequency, the luminous efficiency is high. [Embodiment]
[0020] 請參閱圖2，係本發明背光控制電路一較佳實施方式之示 意圖。該背光控制電路200包括一背光燈250、一反相電 路240、一脈寬調變積體電路220、一燈管識別電路260 及一頻率調整電路230。該背光燈250係一冷陰極射線管 。該脈寬調變積體電路220之型號為OZ9910。 [0021] 該頻率調整電路230包括一數位可變電阻232、一電容 231、一查詢表234及一譯碼器235。請一併參閱圖3，係 該查詢表234之示意圖。該查詢表234存儲複數燈管類型（ 如：1、2........η型）及代表該類型燈管之最佳工作頻 率之二進制指令（如：11100111、1 1 1 00000 ........ 11111111)。該脈寬調變積體電路220包括一頻率設定端 221及一電源端222，該頻率設定端221經由該電容231接 地。 [0022] 該數位可變電阻232包括複數電阻2321及複數開關元件 2322。每一開關元件2322包括一第一導通端1、一第二 導通端2及一控制端3。該複數電阻2321構成一串聯支路 ，該串聯支路之一端（未標示）連接該電源端222，另一端 (未標示）經由一開關元件2322之第二導通端2、第一導通 端1連接該頻率設定端221，每相鄰二電阻2321間之電路 096120807 表單編號 Α0101 第 6 頁/共 17 頁 0993387248-0 1337731 099年10月27日核正替換頁 節點2323經由一開關元件2322之第二導通端2、第一導 通端1連接該頻率設定端221。該譯碼器235包括複數輸出 端（未標示），每一輸出端對應連接一開關元件2322之一 控制端3。 [0023] 該背光控制電路200工作時，該數位可變電阻232具一初 始阻值。 [0024] 該背光控制電路200之工作原理如下： [0025] 該脈寬調變積體電路220根據該數位可變電阻232之初始 阻值及該電容231產生一脈衝訊號至該反相電路240。 [0026] 該反相電路240根據該脈衝訊號將一直流電壓轉換為交流 電壓驅動該背光燈250，該背光燈250啟動並發光。 [0027] 該燈管識別電路260採樣該背光燈250從啟動之後一段時 間内之電壓及電流，並根據該電壓變化及電流變化分析 出該背光燈之燈管類型（如：1、2........η型，假設為1 型），輸出代表該燈管類型（1型）之訊號至該查詢表234。 [0028] 該查詢表234根據該燈管類型（1型）之訊號查詢出該類型 燈管（1型）對應之最佳工作頻率之二進制指令 (11100111)，並輸出該二進制指令（11 1001 11)至該譯 碼器235。 [0029] 該譯碼器235解碼該二進制指令（11100111)，藉由控制 該數位可變電阻232之複數開關元件2322之導通或不導通 ，調整該數位可變電阻232之阻值。 [0030] 該脈寬調變積體電路220根據該數位可變電阻232之阻值 096120807 表單編號 Α0101 第 7 頁/共 17 頁 0993387248-0 B37731 099年10月27日核正替換頁 調整輸出之脈衝訊號之頻率。該反相電路240根據調整後 之脈衝訊號調整輸出之交流電壓之頻率，從而該背光燈 250工作在最佳工作頻率。 [0031] 相較於先前技術，該背光控制電路2 0 0之燈管識別電路 260根據該背光燈250從啟動之後一段時間内之電壓及電 流，識別該背光燈250之燈管類型，該頻率調整電路230 根據該燈管類型調整該脈衝调變積體電路220輸出之脈衝 訊號之頻率，進而該反相電路240調整輸出之交流電壓之 頻率，使該背光燈250工作在最佳工作頻率，發光效率較 南。 [0032] 本發明背光控制電路及其控制方法亦可具其他多種變更 設計，如：採用不同之脈衝調變積體電路220時，其與該 頻率調整電路230之連接方式不同，如當採用該脈衝調變 積體電路220採用QZ960時，其與頻率設定電路230連接 之二端分別為第一頻率設定端及第二頻率設定端，且該 第一頻率設定端經由該電容231接地，該第二頻率設定端 經由該數位可變電阻232接地。 [0033] 綜上所述，本發明確已符合發明專利之要件，爰依法提 出專利申請。惟，以上所述者僅為本發明之較佳實施方 式，本發明之範圍並不以上述實施方式為限，舉凡熟習 本案技藝之人士援依本發明之精神所作之等效修飾或變 化，皆應涵蓋於以下申請專利範圍内。 【圖式簡單說明】 [0034] 圖1係一種先前技術背光控制電路之示意圖。 096120807 表單編號A0101 第8頁/共17頁 0993387248-0 1337731 099年10月27日梭正替換頁 [0035] 圖2係本發明背光控制電路一較佳實施方式之示意圖。 [0036] 圖3係圖2所示背光驅動電路之部份示意圖。 【主要元件符號說明】 [0037] 背光控制電路：200 [0038] 電源端：222 [0039] 脈寬調變積體電路：220 [0040] 數位可變電阻：232Please refer to FIG. 2, which is a schematic diagram of a preferred embodiment of the backlight control circuit of the present invention. The backlight control circuit 200 includes a backlight 250, an inverting circuit 240, a pulse width modulation integrated circuit 220, a lamp identification circuit 260, and a frequency adjustment circuit 230. The backlight 250 is a cold cathode ray tube. The model of the pulse width modulation integrated circuit 220 is OZ9910. [0021] The frequency adjustment circuit 230 includes a digital variable resistor 232, a capacitor 231, a lookup table 234, and a decoder 235. Please refer to FIG. 3 together for a schematic diagram of the lookup table 234. The lookup table 234 stores a plurality of lamp types (e.g., 1, 2, ..., η type) and binary instructions representing the optimum operating frequency of the type of lamp (e.g., 11100111, 1 1 1 00000 . ....... 11111111). The pulse width modulation integrated circuit 220 includes a frequency setting terminal 221 and a power terminal 222. The frequency setting terminal 221 is grounded via the capacitor 231. [0022] The digital variable resistor 232 includes a complex resistor 2321 and a plurality of switching elements 2322. Each switching element 2322 includes a first conductive terminal 1, a second conductive terminal 2, and a control terminal 3. The plurality of resistors 2321 form a series branch, one end of the series branch (not shown) is connected to the power terminal 222, and the other end (not shown) is connected via the second conducting end 2 of the switching element 2322, and the first conducting end 1 The frequency setting terminal 221, the circuit between each adjacent two resistors 2321 096120807, the form number Α 0101, the sixth page, the total replacement page node 2323, the second through a switching element 2322 The conduction terminal 2 and the first conduction terminal 1 are connected to the frequency setting terminal 221. The decoder 235 includes a plurality of outputs (not shown), and each of the outputs is connected to a control terminal 3 of a switching element 2322. [0023] When the backlight control circuit 200 is in operation, the digital variable resistor 232 has an initial resistance value. The operating principle of the backlight control circuit 200 is as follows: [0025] The pulse width modulation integrated circuit 220 generates a pulse signal to the inverter circuit 240 according to the initial resistance of the digital variable resistor 232 and the capacitor 231. . The inverter circuit 240 converts the DC voltage to an AC voltage according to the pulse signal to drive the backlight 250, and the backlight 250 is activated and emits light. [0027] The lamp identification circuit 260 samples the voltage and current of the backlight 250 from a period of time after the startup, and analyzes the lamp type of the backlight according to the voltage change and the current change (eg, 1, 2... ... η type, assumed to be type 1), the signal representing the lamp type (type 1) is output to the lookup table 234. [0028] The lookup table 234 queries the binary instruction (11100111) of the optimal operating frequency corresponding to the type of the lamp (type 1) according to the signal of the lamp type (type 1), and outputs the binary instruction (11 1001 11). ) to the decoder 235. The decoder 235 decodes the binary command (11100111), and adjusts the resistance of the digital variable resistor 232 by controlling whether the plurality of switching elements 2322 of the digital variable resistor 232 are turned on or off. [0030] The pulse width modulation integrated circuit 220 is based on the resistance value of the digital variable resistor 232 096120807 Form No. 101 0101 Page 7 / Total 17 Page 0993387248-0 B37731 October 27, 1999 Nuclear replacement page adjustment output The frequency of the pulse signal. The inverter circuit 240 adjusts the frequency of the output AC voltage according to the adjusted pulse signal, so that the backlight 250 operates at the optimum operating frequency. [0031] Compared to the prior art, the lamp control circuit 260 of the backlight control circuit 200 identifies the lamp type of the backlight 250 according to the voltage and current of the backlight 250 from a period of time after startup, the frequency The adjustment circuit 230 adjusts the frequency of the pulse signal outputted by the pulse modulation integrated circuit 220 according to the type of the lamp, and the inverter circuit 240 adjusts the frequency of the output AC voltage to operate the backlight 250 at the optimal operating frequency. The luminous efficiency is relatively south. [0032] The backlight control circuit and the control method thereof may also have various other modified designs. For example, when different pulse modulation integrated circuits 220 are used, the connection manner with the frequency adjustment circuit 230 is different, for example, when When the pulse modulation integrated circuit 220 is QZ960, the two ends connected to the frequency setting circuit 230 are respectively a first frequency setting end and a second frequency setting end, and the first frequency setting end is grounded via the capacitor 231. The two frequency setting terminals are grounded via the digital variable resistor 232. [0033] In summary, the present invention has indeed met the requirements of the invention patent, and the patent application is filed according to law. However, the above description is only the preferred embodiment of the present invention, and the scope of the present invention is not limited to the above-described embodiments, and those skilled in the art will be able to make equivalent modifications or changes in accordance with the spirit of the present invention. It should be covered by the following patent application. BRIEF DESCRIPTION OF THE DRAWINGS [0034] FIG. 1 is a schematic diagram of a prior art backlight control circuit. 096120807 Form No. A0101 Page 8 of 17 0993387248-0 1337731 October 27, 2008, the replacement page [0035] FIG. 2 is a schematic view of a preferred embodiment of the backlight control circuit of the present invention. 3 is a partial schematic view of the backlight driving circuit shown in FIG. 2. [Main component symbol description] [0037] Backlight control circuit: 200 [0038] Power supply terminal: 222 [0039] Pulse width modulation integrated circuit: 220 [0040] Digital variable resistance: 232
[0041] 頻率調整電路：230 [0042] 譯碼器：235 [0043] 反相電路：2 4 0 [0044] 開關元件：2322 [0045] 背光燈：250 [0046] 電阻：2321[0041] Frequency adjustment circuit: 230 [0042] Decoder: 235 [0043] Inverting circuit: 2 4 0 [0044] Switching element: 2322 [0045] Backlight: 250 [0046] Resistance: 2321
[0047] 燈管識別電路：2 6 0 [0048] 第一導通端：1 [0049] 頻率設定端：221 [0050] 第二導通端：2 [0051] 查找表：234 [0052] 節點：2323 [0053] 電容：231 096120807 表單編號A0101 第9頁/共17頁 09933872Ί8-0 1337731 099年10月27日按正替換頁 [0054] 控制端：3 096120807 表單編號A0101 第10頁/共17頁[0047] Lamp identification circuit: 2 6 0 [0048] First conduction end: 1 [0049] Frequency setting end: 221 [0050] Second conduction end: 2 [0051] Lookup table: 234 [0052] Node: 2323 [0053] Capacitance: 231 096120807 Form No. A0101 Page 9 / Total 17 Page 09933872 Ί 8-0 1337731 October 27, 2017 Press the replacement page [0054] Console: 3 096120807 Form No. A0101 Page 10 of 17
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