201009786 九、發明說明： 【發明所屬之技術領域】 本發明是有關於一種背光源亮度控制方法，特別是指 一種以脈寬調變訊號控制螢幕背光的螢幕背光源亮度控制 方法。 【先前技術】 現今各種電子裝置例如液晶顯示器、可攜式導航裝置 (Portable Navigation Device，PND)等的螢幕背光源多採用 參 冷陰極螢光燈管（Cold Cathode Fluorescent Lamp，CCFL)及 發光二極體（LED)兩種，而在諸多LED背光源亮度控制的方 法中，其中一種是利用脈衝寬度調變（Pulse Width Modulation，PWM)技術來完成，其控制的原理是由一系統 晶片（System-on-a-Chip，SoC)提供一脈寬調變訊號及電源給 一背光控制1C，使依脈寬調變訊號的責任週期（duty cycle) 不同來調整輸出至LED背光源的電流大小，進而控制且維 持背光源的亮度。而當控制背光源從關閉（OFF)到開啟（ON) ® 時，系統晶片是直接提供一其責任週期對應背光源所需亮 度的脈寬調變訊號及電源給背光控制1C，使直接點亮背光 源，而當要關閉背光源時，系統晶片則停止輸出脈寬調變 訊號及電源給背光控制1C，使背光源熄滅。然而此種控制 方式使得背光源一下子從暗轉亮或從亮轉暗，容易導致使 用者眼睛感到不適，且在視覺上亦不甚美觀。 【發明内容】 因此，本發明之目的，即在提供一種可以漸進式調整 201009786 背光源亮度的背光源亮度控制方法。 於疋，本發明背光源亮度控制方法是用以提供一脈寬 調變訊號給-背光控制電路，使該背光控制電路控制-背 光源的亮度漸進地改變，該方法包含以下步驟： (a) 設定該脈寬調變訊號的一目標責任週期； (b) 改變該脈寬調變訊號的責任週期，且改變量小於該 脈寬調變訊號的目標責任週期與初始責任週期之差值的絕 對值，並提供該脈寬調變訊號給該背光控制電路； (c) 判斷該脈寬調變訊號的責任週期是否達到目標責任 週期，若是’執行步驟（d)，否則重複步驟（b);及 (d) k供s玄脈寬調變訊號給該背光控制電路。本發明之 功效在於，漸進式的調整背光源的亮度，可避免使用者眼 睛不會因為畫面瞬間變化而感到不適，且又可以增加視覺 上的美觀。 【實施方式】 有關本發明之前述及其他技術内容、特點與功效，在 以下配合參考圖式之一個較佳實施例的詳細說明中，將可 清楚的呈現。 參閱圖1，為本發明背光源亮度控制裝置之較佳實施例 ’該控制裝置1主要是應用於電子裝置2的螢幕背光源， 例如液晶顯示器、可攜式導航裝置（Portable Navigation Device，PND)等，用以產生一脈寬調變訊號給背光控制電 路3，使其可以漸進地調整背光源4的亮度。本發明之控制 裝置1可以整合於一系統晶片（System-on-a-Chip，SoC)，其 201009786 中並包括一控制單元11及一脈寬調變模組（Pulse width201009786 IX. Description of the Invention: [Technical Field] The present invention relates to a backlight brightness control method, and more particularly to a screen backlight brightness control method for controlling a screen backlight with a pulse width modulation signal. [Prior Art] Today, various electronic devices such as liquid crystal displays, portable navigation devices (PNDs), etc. use backlights such as Cold Cathode Fluorescent Lamps (CCFLs) and LEDs. Body (LED) two, and in the method of brightness control of many LED backlights, one of them is completed by Pulse Width Modulation (PWM) technology, the principle of which is controlled by a system chip (System- On-a-Chip, SoC) provides a pulse width modulation signal and power supply to a backlight control 1C, so that the duty cycle of the pulse width modulation signal is different to adjust the current output to the LED backlight, and then Control and maintain the brightness of the backlight. When the backlight is controlled from OFF to ON, the system chip directly provides a pulse width modulation signal and power supply to the backlight control 1C for the required brightness of the backlight according to the duty cycle, so that the backlight is directly lit. The backlight, when the backlight is to be turned off, the system chip stops outputting the pulse width modulation signal and the power supply to the backlight control 1C, so that the backlight is turned off. However, this type of control makes the backlight turn from dark to light or from light to dark, which easily causes the user's eyes to feel uncomfortable and visually unattractive. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a backlight brightness control method that can progressively adjust the brightness of a 201009786 backlight. In the present invention, the backlight brightness control method of the present invention is for providing a pulse width modulation signal to the backlight control circuit, so that the backlight control circuit controls the brightness of the backlight to be changed progressively. The method comprises the following steps: (a) Setting a target duty cycle of the pulse width modulation signal; (b) changing the duty cycle of the pulse width modulation signal, and the amount of change is less than the absolute difference between the target duty cycle of the pulse width modulation signal and the initial duty cycle And providing the pulse width modulation signal to the backlight control circuit; (c) determining whether the duty cycle of the pulse width modulation signal reaches a target duty cycle, if it is 'execution step (d), otherwise repeating step (b); And (d) k for the sinusoidal wide modulation signal to the backlight control circuit. The effect of the present invention is that the brightness of the backlight is gradually adjusted to prevent the user's eyes from feeling uncomfortable due to momentary changes in the picture, and to increase visual aesthetics. The above and other technical contents, features, and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments. 1 is a preferred embodiment of a backlight brightness control device of the present invention. The control device 1 is mainly applied to a screen backlight of an electronic device 2, such as a liquid crystal display or a portable navigation device (PND). And the like, for generating a pulse width modulation signal to the backlight control circuit 3, so that the brightness of the backlight 4 can be gradually adjusted. The control device 1 of the present invention can be integrated into a System-on-a-Chip (SoC), which includes a control unit 11 and a pulse width modulation module (Pulse width) in 201009786.
Modulation’PWM)12。控制單元u _於脈寬調變模組 12,並控制脈寬調變模組12產生一脈寬調變訊號，而背光 控制電路3純於脈寬調變模組12，且根據該脈寬調變訊 號的責任週期（duty cycle)，對耦接於背光控制電路3的背 光源4的亮度作調整。在本實施例中，脈寬調變訊號的責 任週期與亮度成正比，也就是說責任週期越大則亮度越高 ’當然’脈寬調變訊號的責任週期與亮度亦可成反比關係 ，責任週期越小則亮度越高，不以本實施例為限。 參閱圖2’本發明背光源亮度控制方法可由-個儲存在 電腦可讀取記錄媒體（例如設在控制裝置丨中的快閃記憶體 (flash))中的軟體程式來實現，以供控制單&丨中讀取並載 入執行。由於電子裝置2的背光源4從開到關(其亮度從亮 到全暗）的控制原理與背光源4從關到開（其亮度從全暗到亮 )相同’故以下將只以背光源4從關到開來說明控制單元】 的控制流程。 步驟51開始背光源4為關閉，即背:¾控制電路3 控制背光源4亮度為全暗（第一亮度），當背光源4欲要被開 啟時控制單元11會從一暫存器(圖未示)讀取預設的脈寬 調變訊號的目標責任週期，在此假設該目標責任週期為 50%。 步驟52 ’控制單元11控制脈寬調變模組12，使其脈寬 調變訊號的責任週期增加1%，也就是該脈寬調變訊號的責 任週期變S 1/0 ’且脈寬調變模組12會將此脈寬調變訊號 201009786 提供至背光控制電路3， 生對應的亮度。 使輪出對應的電流驅動背光源 4產 53 #制單70 11判斷脈寬調變訊號的責任週期是 否j到5G% ’右疋則執行步驟54，否則重複執行步驟η。 換。之*於脈寬調變訊號的責任週期已在上述步驟改變 為1/。但疋仍未達到5〇%，故會跳回步驟52並重複步驟 53及52直到脈寬調變模組12輸出的脈寬調變訊號的責任 週期達到50/。’且在脈寬調變模組12輸出脈寬調變訊號的 責任週期逐漸遞增的過程中，背光控制電路3會對應產生〇 逐漸遞增的電流驅動背光源4，使得背光源4的亮度逐漸增 加至一定值（第二亮度）’而完成漸進點亮背光源4的程序。 步驟54’因此，當脈寬調變模組12輸出之脈寬調變訊 號的責任週期已經達到點亮背光源4的目標責任週期（5〇%) 後，脈寬調變模組12則會持續輸出責任週期為5〇%的脈寬 調變訊號至背光控制電路3，使背光控制電路3對應控制背 光源4維持在該亮度。 值得一提的是，上述步驟51中，脈寬調變訊號的目標© 責任週期並不以本實施例所假設的50%為限，其可為前一 次電子裝置2在使用時，背光源4亮度所對應的脈寬調變 訊號之責任週期，舉例來說，若電子裝置2之前是在脈寬 調變訊號的責任週期為60%的背光源4亮度下被關閉，則 控制單元11會在電源消失之前，在暫存器中將目標責任週 期設定為60%，因此當電子裝置2重新被開啟時，其背光 源4經過上述步驟51〜53後將會被設定為脈寬調變訊號的 201009786 責任週期為60%時的亮度。 的增號的初始責任週期為°%，而每-次 變，其責任i/ 疋說脈寬調變訊號會歷經50次的調 ，，=週期才會達到目標責任週期，而在遞增的過程 使用J 亮度亦會隨著責任週期的增加而漸亮，故 吏：者：眼睛不會有因背光源4 一下子從暗轉亮所導致的 適。虽然’每次責任週期的增加量會與歷經調變的次數Modulation'PWM) 12. The control unit u _ is in the pulse width modulation module 12, and controls the pulse width modulation module 12 to generate a pulse width modulation signal, and the backlight control circuit 3 is pure to the pulse width modulation module 12, and according to the pulse width The duty cycle of the modulation signal adjusts the brightness of the backlight 4 coupled to the backlight control circuit 3. In this embodiment, the duty cycle of the pulse width modulation signal is proportional to the brightness, that is, the greater the duty cycle, the higher the brightness. Of course, the duty cycle and the brightness of the pulse width modulation signal may also be inversely related. The smaller the period, the higher the brightness, which is not limited to this embodiment. Referring to FIG. 2', the backlight brightness control method of the present invention can be implemented by a software program stored in a computer readable recording medium (for example, a flash memory provided in the control device) for the control list. &丨 reads and loads the execution. Since the control principle of the backlight 4 of the electronic device 2 from on to off (its brightness is from bright to full dark) is the same as that of the backlight 4 from off to on (the brightness is from full dark to bright), the following will only be used as a backlight. 4 From the off to the opening to explain the control flow of the control unit. Step 51 starts the backlight 4 is off, that is, the back: 3⁄4 control circuit 3 controls the brightness of the backlight 4 to be full dark (first brightness), and when the backlight 4 is to be turned on, the control unit 11 will be from a register (Fig. The target duty cycle of the preset pulse width modulation signal is read, and the target duty cycle is assumed to be 50%. Step 52 The control unit 11 controls the pulse width modulation module 12 to increase the duty cycle of the pulse width modulation signal by 1%, that is, the duty cycle of the pulse width modulation signal changes to S 1/0 ' and the pulse width adjustment The variable module 12 provides the pulse width modulation signal 201009786 to the backlight control circuit 3 to generate a corresponding brightness. To make the corresponding current drive the backlight 4 production 53 #制单70 11 to determine whether the duty cycle of the pulse width modulation signal is j to 5G% ‘right 疋 then step 54 is performed, otherwise step η is repeated. change. The duty cycle of the pulse width modulation signal has been changed to 1 in the above steps. However, 疋 has not yet reached 〇5%, so it will jump back to step 52 and repeat steps 53 and 52 until the duty cycle of the pulse width modulation signal output by the pulse width modulation module 12 reaches 50/. In the process of gradually increasing the duty cycle of the pulse width modulation module 12 outputting the pulse width modulation signal, the backlight control circuit 3 drives the backlight 4 correspondingly to generate a gradually increasing current, so that the brightness of the backlight 4 is gradually increased. The program for progressively lighting the backlight 4 is completed to a certain value (second brightness). Step 54 ′ Therefore, when the duty cycle of the pulse width modulation signal output by the pulse width modulation module 12 has reached the target duty cycle (5〇%) of the backlight 4, the pulse width modulation module 12 The pulse width modulation signal with a duty cycle of 5〇% is continuously outputted to the backlight control circuit 3, so that the backlight control circuit 3 controls the backlight 4 to maintain the brightness. It is worth mentioning that, in the above step 51, the target © responsibility period of the pulse width modulation signal is not limited to 50% assumed in the embodiment, and may be the backlight 4 of the previous electronic device 2 when in use. The duty cycle of the pulse width modulation signal corresponding to the brightness, for example, if the electronic device 2 is turned off before the brightness of the backlight 4 of the duty cycle of the pulse width modulation signal is 60%, the control unit 11 will Before the power supply disappears, the target duty cycle is set to 60% in the register, so when the electronic device 2 is turned back on, the backlight 4 will be set to the pulse width modulation signal after the above steps 51 to 53 are performed. 201009786 Brightness at 60% duty cycle. The initial duty cycle of the sign increment is °%, and for each change, its responsibility i/ 疋 says that the pulse width modulation signal will undergo 50 adjustments, and the cycle will reach the target responsibility cycle, while the process of incrementing The brightness of J will also fade with the increase of the duty cycle, so: The eyes will not be suitable for the backlight 4 to turn from dark to dark. Although the amount of increase in each duty cycle will be the number of times it has been modulated
成反比’例如每次責任週期增加2%，則只需25次的調變 即可達到目標責任週期。另外，責任週期的增加量也可以 ^二欠皆不相同’但是不管是使用哪種方法，其增加量的總 口會皆為脈寬調變訊號的目標責任週期與初始責任週期之 差值的絕對值。 同樣地，針對電子裝置2的背光源4從開啟到關閉， 亦可藉由上述方式’只是脈寬調變訊號的目標責任週期為 〇%’且脈寬調變訊號的責任週期會從某一定值(即背光源4 開啟時對應的脈寬調變訊號的責任週期）遞減至〇%，而背光 源4亮度會隨著責任週期的減少而漸暗，故使用者亦不會 因為畫面亮度的瞬間變化而感到不適。此外，本發明背光 源亮度控制方法不僅用於背光源4在開啟與關閉之間切換 的兩個狀態而已，亦可用於當電子裝置2進入省電模式而 使背光源4亮度減弱時，只要脈寬調變訊號的目標責任週 期被改變，控制單元11皆可以利用本發明之控制方法漸 進式的改變背光源4為對應該目標責任週期的亮度。 综上所述’本發明背光源亮度控制方法藉由漸進式的 9 201009786 改變脈寬調變訊號的責任週期，使得背光源會隨著責任週 期而漸進式地調整，不僅不會有因背光源瞬間改變亮度而 導致使用者眼睛的不適，也更增加了美觀。 惟以上所述者，僅為本發明之較佳實施例而已，當不 能以此限定本發明實施之範圍，即大凡依本發明申請專利 範圍及發明說明内容所作之簡單的等效變化與修飾，皆仍 屬本發明專利涵蓋之範圍内。 【圖式簡單說明】 圖1是-電路方塊示意圖，說明本發明背光源亮度^ 制裝置之較佳實施例；及 圖2是-流程圖，說明本發明背光源亮度控制方法。 10 201009786 【主要元件符號說明】 51〜54步驟 I ..........控制裝置 3 II .........控制單元 12.........脈寬調變模組 電子裝置 背光控制電路 背光源In inverse proportion, for example, each duty cycle increases by 2%, then only 25 adjustments can be achieved to achieve the target responsibility cycle. In addition, the increase in the duty cycle can also be different. However, no matter which method is used, the total amount of the increase will be the difference between the target duty cycle of the pulse width modulation signal and the initial duty cycle. Absolute value. Similarly, for the backlight 4 of the electronic device 2 to be turned on or off, the target duty cycle of the pulse width modulation signal is 〇%', and the duty cycle of the pulse width modulation signal will be from a certain degree. The value (that is, the duty cycle of the corresponding pulse width modulation signal when the backlight 4 is turned on) is reduced to 〇%, and the brightness of the backlight 4 is dimmed as the duty cycle is reduced, so the user does not have the brightness of the screen. I feel uncomfortable when I change instantly. In addition, the backlight brightness control method of the present invention is not only used for two states in which the backlight 4 is switched between on and off, but also can be used when the electronic device 2 enters the power saving mode and the brightness of the backlight 4 is weakened. The target duty cycle of the wide-tuning signal is changed, and the control unit 11 can progressively change the backlight 4 to the brightness corresponding to the target duty cycle by using the control method of the present invention. In summary, the backlight brightness control method of the present invention changes the duty cycle of the pulse width modulation signal by the progressive 9 201009786, so that the backlight is gradually adjusted along with the duty cycle, and there is no backlight. Instantly changing the brightness causes discomfort to the user's eyes and also increases the appearance. The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a preferred embodiment of a backlight luminance control device of the present invention; and FIG. 2 is a flow chart illustrating a backlight brightness control method of the present invention. 10 201009786 [Description of main component symbols] 51 to 54 Step I ..... Control device 3 II ......... Control unit 12......... Pulse width Modulation module electronic device backlight control circuit backlight
1111