201201178 六、發明說明： 【發明所屬之技術領域】 本發明是有關於一種驅動電路及具有該驅動電路之晝 素電路，特別是指一種可以改善臨界電壓漂移效應及發光 元件老化之驅動電路及具有該驅動電路之晝素電路。 【先前技術】 一有機發光二極體（OLED )的亮度是與其驅動電流 成一正比例關係的。而目前當應用〇LED於一顯示系統 時’其與對應之驅動電路的連結仍普遍存在著以下的問題 一為驅動電路中的電晶體的臨界電壓可能因為製程變 異的關係而造成漂移現象，導致〇LED的驅動電流不穩定 ，進而使得OLED的亮度隨之發生不穩定的現象，其二為 OLED因為材料老化或是長時間操作下，容易發生〇LED兩 端跨壓逐漸上升導致發光效率下降的問題，因為跨壓的上 升會影響OLED的驅動電流發生衰減現象，而驅動電流衰 減就會造成OLED亮度衰減《此外，現今技術中對於晝素 補乜電路的設計多半使用過多的電晶體，這將會使得晝素 内開口率出現衰減甚至過低的現象，因此有必要找出一種 可以有效抑制因電晶體臨界電壓漂移及〇LED老化所造成 的驅動電流衰減現象，使得〇LED亮度得以保持穩定的方 法，同時，又必須利用精簡的電路設計使得晝素開口率 以保持。 【發明内容】 201201178 因此，本發明之目的，即在提供一種畫素電路，包含 一發光單元，具有一第一端與一第二端；及 一驅動電路，包括： 一第一電晶體，具有一第一端、一第二端，及一決 定該第一端及該第二端是否導通的控制端； 一電容； 一第一開關，具有一第一端與一第二端；及 ~第二開關，具有一第一端與一第二端； 其中，該發光單元之第一端接收一第一電源電壓及該 第一電晶體之第二端接收一第二電源電壓，該第一開關之 第一端與該第一電晶體之第一端電連接，該第一開關之第 二端與該第一電晶體之控制端電連接，且該第一開關接收 一第一控制訊號，以決定該第一電晶體之第一端、及控制 端是否電連接，而該第二開關之第一端與該發光單元之第 二端電連接，該第二開關之第二端與該第一電晶體之第一 電連接，且該第二開關接收一第二控制訊號，以決定該 發光單元之第二端與該第一電晶體之第一端是否電連接， 該電容之一端與該第一電晶體之控制端電連接，且該電容 之另一端接收一資料電壓，並根據該第一開關及該第二開 關之導通狀態以控制該發光單元之一驅動電流。 此外，本發明另外提供一種驅動電路，用以控制—具 有一第一端與一第二端之發光單元，其包含： 、 -第-電晶體’具有一第一端、一第二端，及一決定 201201178 該第一端及該第二端是否導通的控制端； 一電容； 一第一開關’具有—第—端與一第二端；及 —第二開關’具有-第-端與-第二端； -發光單元，具有一第—端與一第二端；及 一驅動電路，包括： 第-電晶體’具有—第一端、一第二端，及一決 疋§玄第—端及該第二端是否導通的控制端； 一電容； -第-開關，具有—第一端與一第二端；及 -第二開關，具有_第一端與一第二端； 其中’該發光單元之第一端接收一第一電源電壓及該 電晶體之第二端接收—第二電源電壓，該第一開關之 第-端與該第一電晶體之第一端電連接，該第一開關之第 -端與該[電晶體之控制端電連接，且該^開關接收 一第-控制tfl號’以決定該第—電晶體之第—端、及控制 端是否電連接’而該第二開關之第—端與該發光單元之第 -端電連接，$第二開關之第二端與該第—電晶體之第一 端電連接，且該第二開關接收一第二控制訊號，以決定該 發光單元之第二端與㈣-電晶體之第-端是否電連接， 該電容之-端與該第一電晶體之控制端電連接，且該電容 之另-端接收-資料電麼，並根據該第一開關及該第二開 關之導通狀態以控制該發光單元之一驅動電流。 此外’本發明另外提供-種畫素電路，包含： 201201178 一發光單元，具有一第一端與一第二端；及 一驅動電路，包括： 第一電晶體’具有一第一端、一第二端，及一 決定該第一端及該第二端是否導通的控制端； 一電容； 一第一開關，具有一第一端與一第二端； 一第二開關，具有一第一端與一第二端； 一第三開關，具有一第一端與一第二端； 其中，該發光單元之第一端接收一第一電源電壓及該 第一電晶體之第二端接收一第二電源電壓，該第一開關之 第一端與該第一電晶體之第一端電連接，該第一開關之第 一端與該第一電晶體之控制端電連接，且該第一開關接收 一第一控制訊號，以決定該第一電晶體之第一端、及控制 端是否電連接，而該第二開關之第一端與該發光單元之第 二端電連接，該第二開關之第二端與該第一電晶體之第一 端電連接，且該第二開關接收一第二控制訊號，以決定該 發光單元之第二端與該第一電晶體之第一端是否電連接， 該第三開關之第一端接收一資料電壓，且該第三開關之第 二端與該第二開關之第一端、該發光單元之第二端電連接 ，該第三開關接收一第三控制訊號以決定該第三開關之第 一端與第二端是否電連接’該電容之一端與該第一電晶體 之控制端電連接，且該電容之另一端接收一資料電壓，並 根據該第一開關之導通狀態以控制該發光單元之一驅動電 流。 201201178 此外本發明另外提供-種驅動電路，用以控制一具 有一第—端與-第二端之發光單元，其包含： 一第一電晶體’具有-第-端、-第二端，及一決定 該第-端及該第二端是否導通的控制端； 一電容； 一第一開關，具有一第一端與一第二端； 一第二開關’具有-第-端與-第二端；及 一第二開關，具有—第一端與一第二端； 其中’該#光單元之第—端接收一第一電源電壓及該 第-電晶體之第二端接收—第二電源電壓，該第一開關之 第-端與該第-電晶體之第一端電連接’肖第—開關之第 二端與該第一電晶體之控制端電連接，且該第一開關接收 一第一控制訊號，以決定該第一電晶體之第一端、及控制 端是否電連接，而該第二開關之第一端與該發光單元之第 二端電連接，該第二開關之第二端與該第一電晶體之第一 鈿電連接，且該第二開關接收一第二控制訊號，以決定該 發光單元之第二端與該第一電晶體之第一端是否電連接， 該第三開關之第一端接收一資料電壓，且該第三開關之第 二端與該第二開關之第一端、該發光單元之第二端電連接 ’該第二開關接收一第三控制訊號以決定該第三開關之第 一端與第一端疋否電連接’該電容之一端與該第一電晶體 之控制端電連接’且該電容之另一端接收一資料電壓，並 根據該第一開關之導通狀態以控制該發光單元之一驅動電 流0 201201178 【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二個較佳實施例的詳細說明中，將可 清楚的呈現。 在本發明被詳細描述之前，要注意的是，在以下的說 明内容中，類似的元件是以相同的編號來表示。 第一較佳實旅例 在一面板中具有多數個晝素，並依其解析度的不同而 有不同數量的列，舉例來說，一 WMxioso解析度之面板 具有1080個列，每一列上具有192〇個畫素，而位於同一 列的該等晝素電路是於同一週期資料輸入對應之資料電壓 ，因此，本實施例是一面板之第N列中的一晝素之晝素電 路。 參閱圖1，本發明之第一較佳實施例包含：一發光單元 1、一驅動電路2，其中，該驅動電路2包括：一第一電晶 體21、一第一開關、一第二開關，及一電容％，在本實施 例中該發光單元1是一有機發光二極體（〇LED),且該第 一開關及第二開關分別以一第二電晶體22及一第三電晶體 23據以實施之，下面說明針對上述該等電晶體皆以N型薄 膜電晶體形式進行說明，但在本發明中舉凡p型薄膜電晶 體、N型金屬氧化物半導體、p型金屬氧化物半導體皆得以 簡易修改而據以實施之，因此不以N型薄膜電晶體為限。 每一電晶體21、22、23皆具有_第一端、一第二端， 及一用以決定該第一端與該第二端是否導通之控制端。而 201201178 該發光單元1 士 一〜有一與一第一電源電壓、電連接之第一端及 _ Λ第二電晶體23之第-端電連接之第二端，該第一電 晶體21之笛 端一該第二電晶體22之第二端、該第三電 晶體23之笙 山^ .一 弟一鳊電連接，該第一電晶體21之第二端電連 、 電源電壓V«，該第一電晶體21之控制端分別與 ^ 一 體22之第—端及該電容24之—端電連接，該 _第:電晶體22' 23之控制端分別接收-第-控制訊 〜及V第—控制訊號’該電容24之另—端電連接於一資料201201178 VI. Description of the Invention: [Technical Field] The present invention relates to a driving circuit and a pixel circuit having the same, and particularly to a driving circuit capable of improving a threshold voltage drift effect and aging of a light emitting element and having The pixel circuit of the drive circuit. [Prior Art] The brightness of an organic light emitting diode (OLED) is proportional to its driving current. At present, when the LED is applied to a display system, the following problems are commonly found in the connection with the corresponding driving circuit. First, the threshold voltage of the transistor in the driving circuit may be drifted due to the variation of the process, resulting in a drift phenomenon. The driving current of the 〇LED is unstable, which in turn causes the brightness of the OLED to be unstable. The second is that the OLED is prone to gradual increase in luminous efficiency due to aging of the LED at the two ends due to aging of the material or long-time operation. The problem, because the rise of the voltage across the IGBT will affect the attenuation of the driving current of the OLED, and the attenuation of the driving current will cause the brightness of the OLED to be attenuated. In addition, in today's technology, the design of the halogen-filled circuit is mostly used too much, which will It will cause the aperture ratio in the halogen to be attenuated or even too low. Therefore, it is necessary to find a kind of driving current attenuation phenomenon caused by the critical voltage drift of the transistor and the aging of the LED, so that the brightness of the LED is kept stable. At the same time, it is necessary to use a streamlined circuit design to ensure the aperture ratio of the element . SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a pixel circuit including a light emitting unit having a first end and a second end, and a driving circuit comprising: a first transistor having a first end, a second end, and a control end determining whether the first end and the second end are conductive; a capacitor; a first switch having a first end and a second end; and The second switch has a first end and a second end; wherein the first end of the light emitting unit receives a first power voltage and the second end of the first transistor receives a second power voltage, the first switch The first end of the first switch is electrically connected to the first end of the first transistor, and the first end of the first switch is electrically connected to the control end of the first transistor, and the first switch receives a first control signal to Determining whether the first end of the first transistor and the control end are electrically connected, and the first end of the second switch is electrically connected to the second end of the light emitting unit, and the second end of the second switch is opposite to the first end a first electrical connection of the transistor, and the second switch receives a first a second control signal to determine whether the second end of the light emitting unit is electrically connected to the first end of the first transistor, one end of the capacitor is electrically connected to the control end of the first transistor, and the other end of the capacitor is received a data voltage, and controlling a driving current of one of the light emitting units according to a conduction state of the first switch and the second switch. In addition, the present invention further provides a driving circuit for controlling a light emitting unit having a first end and a second end, comprising: - a first transistor, a first end, a second end, and a control terminal that determines whether the first end and the second end are conductive; a capacitor; a first switch 'having a first end and a second end; and - a second switch having a - first end - a second end; a light emitting unit having a first end and a second end; and a driving circuit comprising: the first transistor has a first end, a second end, and a second end a control end of whether the terminal and the second end are conductive; a capacitor; a first switch having a first end and a second end; and a second switch having a first end and a second end; wherein The first end of the light emitting unit receives a first power voltage and the second end of the transistor receives a second power voltage, and the first end of the first switch is electrically connected to the first end of the first transistor, The first end of the first switch is electrically connected to the [control terminal of the transistor, and the switch receives a first control The tfl number 'determines whether the first end of the first transistor and the control end are electrically connected' and the first end of the second switch is electrically connected to the first end of the light emitting unit, and the second end of the second switch The second switch is electrically connected to the first end of the first transistor, and the second switch receives a second control signal to determine whether the second end of the light emitting unit is electrically connected to the first end of the (four)-transistor. The end is electrically connected to the control end of the first transistor, and the other end of the capacitor receives the data, and controls the driving current of the one of the light emitting units according to the conduction state of the first switch and the second switch . In addition, the present invention further provides a pixel circuit comprising: 201201178 an illumination unit having a first end and a second end; and a driving circuit comprising: the first transistor 'having a first end, a first a second end, and a control end that determines whether the first end and the second end are conductive; a capacitor; a first switch having a first end and a second end; and a second switch having a first end And a second end; a third switch having a first end and a second end; wherein the first end of the light emitting unit receives a first power voltage and the second end of the first transistor receives a first a first power supply voltage, the first end of the first switch is electrically connected to the first end of the first transistor, the first end of the first switch is electrically connected to the control end of the first transistor, and the first switch Receiving a first control signal to determine whether the first end of the first transistor and the control end are electrically connected, and the first end of the second switch is electrically connected to the second end of the light emitting unit, the second switch The second end is electrically connected to the first end of the first transistor, and The second switch receives a second control signal to determine whether the second end of the light emitting unit is electrically connected to the first end of the first transistor, the first end of the third switch receives a data voltage, and the third The second end of the switch is electrically connected to the first end of the second switch and the second end of the light emitting unit, and the third switch receives a third control signal to determine whether the first end and the second end of the third switch The electrical connection 'one end of the capacitor is electrically connected to the control end of the first transistor, and the other end of the capacitor receives a data voltage, and controls the driving current of one of the light emitting units according to the conduction state of the first switch. 201201178 furthermore, the present invention further provides a driving circuit for controlling a light emitting unit having a first end and a second end, comprising: a first transistor 'having a -first end, a second end, and a control end determining whether the first end and the second end are conductive; a capacitor; a first switch having a first end and a second end; and a second switch 'having a - first end and a second And a second switch having a first end and a second end; wherein the first end of the optical unit receives a first power voltage and the second end of the first transistor receives a second power source a voltage, a first end of the first switch is electrically connected to a first end of the first transistor, and a second end of the switch is electrically connected to a control end of the first transistor, and the first switch receives a a first control signal to determine whether the first end of the first transistor and the control end are electrically connected, and the first end of the second switch is electrically connected to the second end of the light emitting unit, and the second switch The second end is electrically connected to the first turn of the first transistor, and the second switch receives a second control a number to determine whether the second end of the light emitting unit is electrically connected to the first end of the first transistor, the first end of the third switch receives a data voltage, and the second end of the third switch The first end of the second switch is electrically connected to the second end of the light emitting unit. The second switch receives a third control signal to determine whether the first end of the third switch is electrically connected to the first end. Electrically connecting with the control terminal of the first transistor and receiving the data voltage from the other end of the capacitor, and controlling the driving current of the one of the light emitting units according to the conduction state of the first switch. 0 201201178 [Embodiment] Related to the present invention The above and other technical contents, features and effects will be apparent from the following detailed description of the preferred embodiments of the drawings. Before the present invention is described in detail, it is noted that in the following description, similar elements are denoted by the same reference numerals. The first preferred embodiment has a plurality of pixels in a panel and has different numbers of columns depending on the resolution thereof. For example, a panel of WMxioso resolution has 1080 columns, each column has 192 pixels, and the pixel circuits in the same column are the data voltages corresponding to the data input in the same period. Therefore, this embodiment is a pixel circuit in the Nth column of a panel. Referring to FIG. 1 , a first preferred embodiment of the present invention includes: a light emitting unit 1 and a driving circuit 2, wherein the driving circuit 2 includes: a first transistor 21, a first switch, and a second switch. And a capacitor %, in the embodiment, the light-emitting unit 1 is an organic light-emitting diode (〇LED), and the first switch and the second switch are respectively a second transistor 22 and a third transistor 23 According to the implementation, the following description is directed to the above-mentioned transistors in the form of N-type thin film transistors, but in the present invention, all of the p-type thin film transistors, N-type metal oxide semiconductors, and p-type metal oxide semiconductors are used. It can be easily modified and implemented accordingly, so it is not limited to N-type thin film transistors. Each of the transistors 21, 22, 23 has a first end, a second end, and a control end for determining whether the first end and the second end are conductive. And 201201178, the light-emitting unit 1 has a second end electrically connected to a first power supply voltage, a first end electrically connected, and a first end of the second transistor 23, the flute of the first transistor 21 The second end of the second transistor 22 and the second transistor 23 are electrically connected to each other, and the second end of the first transistor 21 is electrically connected to the power supply voltage V«. The control ends of the first transistor 21 are electrically connected to the first end of the integral 22 and the end of the capacitor 24, respectively, and the control terminals of the transistor 22' 23 receive - the first control signal and the V first - control signal 'the other end of the capacitor 24 is electrically connected to a data
、，值得說明的是，因為該第二、第三電晶體22 :3皆：-N型薄膜電晶體，因此，當該第一、第二嫌 號為冋電位時，其對應之第二、第三電晶體22、23之第-^與第二端為導通狀態，反之，當該第—、第二控制Μ 為低電位時’其對應之第二、第三電晶體22、23之第一々 :第二端為不導通狀態。若是該等電晶體是以P型電以It should be noted that, since the second and third transistors 22:3 are all: -N type thin film transistors, when the first and second signs are zeta potential, they correspond to the second, The first and second ends of the third transistor 22, 23 are in an on state, and vice versa, when the first and second control Μ are at a low level, the corresponding second and third transistors 22, 23 One point: the second end is not conducting. If the transistors are P-type
貫現時’其_訊號的電位狀態與對應之P型電晶體之揮 係即為反向之關係。 本實施例之畫素電路的操作模式說明如下： 聯合參閱圖1、2,首先，楚 自无該第一、第二控制訊號皆招 设定為高電位，因此，該第二、第三電晶冑22、23皆被導 通，其中該第一電晶體21之第一 端及其控制端上的電壓皆 為為該發光單元i (即為—有機發光二極體) :第一端及第二端間的跨麼’因此該電容24之兩端電屋差 為-(Vdo) ’ 為該資料電屋。 10 201201178The current state of the signal signal and the corresponding P-type transistor are reversed. The operation mode of the pixel circuit of this embodiment is as follows: Referring to FIG. 1 and FIG. 2 in combination, firstly, the first and second control signals are set to a high potential, and therefore, the second and third powers are The crystals 22 and 23 are both turned on, wherein the voltage at the first end of the first transistor 21 and the control terminal thereof is the light-emitting unit i (ie, the organic light-emitting diode): the first end and the first The cross between the two ends is 'so the difference between the two ends of the capacitor 24 is - (Vdo)' is the data house. 10 201201178
當該電容24充電至V_-〇/DD-V_)後，該畫素電路將操 作於一補償模式，此時第二控制訊號被設定為低電位，使 得該第三電晶體23不導通，因此該電容24透過該第一電 晶體21開始進行放電，直到該第一電晶體21之控制端的 電壓放電至(、，為該第一電晶體21之臨界電壓） ，該第一電晶體21切換為不導通狀態，此時該電容24之 兩端電壓差為-(匕+Vm|)，然後，該第一控制訊號被設定 為低電位’使付§亥第二電晶體22不導通，因此，該電容24 因沒有放電路徑使得其兩端電壓差被保持於_(匕+心1)， 故該晝素電路中的電容24二端電壓可以保持不變，也就是 說，第N列之該等晝素電路中的電容二端電壓皆保持不變 然後，第N+1列晝素電路所對應之第二、第一控制訊 號依序被設定為低電位，使其電容24的兩端電壓差可以保 持固疋，依次類推，直到最後一列畫素電路的電容24的兩 端電壓差保持固定。 然後，該畫素電路操作於一發光模式，每一列晝素電 路的第二控制訊號同時被設定為高電位，使得對應之第三 電晶體23導通’而資料電壓同時亦增加一發光電壓从，此 ，因此’ 1之驅動電流/。^如 時，該第一電晶體21之控制端電壓為 根據下列方程式得以計算出該發光單元 下： 11 201201178 β由上式可知，該發光單元1之驅動電流/。咖與該發光電 壓之平方成正比例關係’因此，該發光單元1之驅動電流When the capacitor 24 is charged to V_-〇/DD-V_), the pixel circuit will operate in a compensation mode, at which time the second control signal is set to a low potential, so that the third transistor 23 is not turned on, The capacitor 24 is discharged through the first transistor 21 until the voltage of the control terminal of the first transistor 21 is discharged to (the threshold voltage of the first transistor 21), and the first transistor 21 is switched to In the non-conducting state, the voltage difference between the two ends of the capacitor 24 is -(匕+Vm|), and then the first control signal is set to a low potential, so that the second transistor 22 is not turned on, therefore, Since the capacitor 24 has no discharge path, the voltage difference between the two ends is maintained at _(匕+心1), so the voltage at the two terminals of the capacitor 24 in the pixel circuit can remain unchanged, that is, the Nth column After the voltages of the two terminals of the capacitor circuit are kept unchanged, the second and first control signals corresponding to the N+1th column of the pixel circuit are sequentially set to a low potential, so that the voltage across the capacitor 24 is The difference can be fixed, and so on, until the capacitance of the last column of pixels 24 Voltage difference remains fixed. Then, the pixel circuit operates in an illumination mode, and the second control signal of each column of the pixel circuit is simultaneously set to a high potential, so that the corresponding third transistor 23 is turned on, and the data voltage is also increased by a light-emitting voltage. This, therefore, '1 drive current /. For example, the control terminal voltage of the first transistor 21 is calculated according to the following equation: 11 201201178 β is the above formula, and the driving current of the light-emitting unit 1 is /. The coffee is proportional to the square of the illuminating voltage. Therefore, the driving current of the illuminating unit 1
Ot£D與該第電晶體2 1之臨界電壓無關，所以可以避免 該第一電晶體21因為製程上的差異或是其長時間操作導致 發生隻異後’其臨界電壓^對於該驅動電流，咖的影響。此 本電路中，由於僅使用二個電晶體，故可以大幅提 昇畫素開口率。 第二較佳實施例 | _參閱圖3，該第一較佳實施例與第一較佳實施例最大的 不同在於，本實施例增加一第三開關，相同於該第一、第 一開關22、23,本實施例中該第三開關是以一第四電晶體 其中，該第四電晶體25亦為一 Ν型薄膜電晶體， 但不以此為限。 該第四電晶體25具有一與該電容24 一端電連接之第 端、一分別與該發光單元1之第二端與該第三電晶體23 之第鳊電連接之第二端，及一接收並根據一第三控制訊籲 號乂决疋其第一端與第二端是否導通之控制端。 本實施例在該畫素電路操作於補償模式之前，先執行 一偵錯模式如下： 田具有該第二開關之畫素電路操作於該偵錯模式時 ’：第-、第二控制訊號設定為低電位、該第三控制訊號 設定為高電位，因此，該第二、第三電晶體m為不導. 通狀I、該第四電晶體25為導通狀態，此時，當該第四電 12 201201178 接收—#料電壓（此時該資料《為輸入 偵錯模時’換句話說，當該晝素電路操作於 以J二’會先輸入一參考電壓值^至該第四電晶體25 *該發光單元進行偵錯’此時，該發光單元丨之兩端跨 二…此時’根據該發光單^之跨壓即可計算出該 ^先早疋1之驅動電流w，然後再根據該發光單元i之理 想驅動電流/_即可計算出一電流衰減率如下： (F.2) a = \~^MAL.Ot£D is independent of the threshold voltage of the first transistor 21, so that the first transistor 21 can be prevented from being caused by the difference in the process or its long-term operation, and its critical voltage is for the driving current. The influence of the coffee. In this circuit, since only two transistors are used, the aperture ratio of the pixel can be greatly increased. Second Preferred Embodiment | Referring to FIG. 3, the first difference between the first preferred embodiment and the first preferred embodiment is that the third switch is added to the first and first switches 22 in this embodiment. In the embodiment, the third switch is a fourth transistor, and the fourth transistor 25 is also a thin film transistor, but is not limited thereto. The fourth transistor 25 has a first end electrically connected to one end of the capacitor 24, a second end electrically connected to a second end of the light emitting unit 1 and a third end of the third transistor 23, and a receiving end. And according to a third control call, the control end of whether the first end and the second end are conductive. In this embodiment, before the pixel circuit operates in the compensation mode, a debug mode is executed as follows: When the pixel circuit having the second switch operates in the debug mode, the first and second control signals are set to The low potential and the third control signal are set to a high potential. Therefore, the second and third transistors m are non-conductive. The first transistor 25 is in an on state, and at this time, the fourth battery 12 201201178 Receive - #料电压 (At this time, the data "for the input debugging mode", in other words, when the pixel circuit operates in J2' will first input a reference voltage value ^ to the fourth transistor 25 * The illuminating unit performs the debugging error. At this time, the two ends of the illuminating unit 跨 cross two... At this time, the driving current w of the first 疋1 can be calculated according to the voltage across the illuminating unit, and then The ideal driving current /_ of the light-emitting unit i can calculate a current decay rate as follows: (F.2) a = \~^MAL.
^IDEAL 其中’《τ為電流衰減率。 因此，當該發光單元1因為材料老化或是使用時間過 長專因素造成驅動電流出現衰減現象時，可以利用上述之 電流衰減率進行補償，其補償方式如下所述： ▲舉例來說，假設該發光單元1之亮度衰減率為0.6,則 s亥發光單元1之驅動電流修正公式如下： 100 100- ~a'^〇LE〇 …··(F.3) 06 其中’ 7_為修正後的驅動電流。 根據方程式㈣，驅動電流是跟發光電壓的平方成正比 例關係，因此，方程式（F·3)可以修改成如下所示. 100 ^'Δν.•…(F.4) 06 13 100- 201201178 因為，，且，其中，為該資 · 料電壓加上該發光電壓Δν之和。 · 所以，方程式（F.4)可以修改成如下所示： ^data ^peak I ~ ' peak " ^DATA) .....(F·5) im-re 因此，該發光單元1操作於該偵錯模式，即可得知為 因應其材料老化等因素所造成的驅動電流衰減現象，該資 料電壓的修正方程式，故藉由本實施例可以避免該發光單 元的老化導致的驅動電流衰減，造成該發光單元i的亮度 · 同步出現衰減的現象。 最後，該第三控制訊號設定為低電位，使該第四電晶 體25不導通，然後輸入該資料電壓並同時設定該第一、第 二控制訊號為高電位，使得該畫素電路如同該第一較佳實 施例所述依序執行於該補償模式、發光模式，以驅動該發 光單元1。 知上所述’藉由本發明之設計，可以有效避免因製程 變異或是使用時間過長所造成的電晶體臨界電壓漂移效應 · ，使得該晝素電路不會因為該臨界電壓漂移效應而影響發 光效率，同時可以有效避免如一有機發光二極體的材料老 化現象所造成驅動電流衰減，進而導致其發光亮度衰減的 現象，此外，本發明之設計相當精簡，利用三至四顆電晶 體及可達到上述目的，因此不會大幅影響開口率，故確實 能達成本發明之目的。 惟以上所述者，僅為本發明之較佳實施例而已，當不 14 201201178 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是本發明之第一較佳實施例之電路圖； 圖2是該第-較佳實施例之時序圖；及 圖3是本發明之第一較佳實施例之電路圖。 15 201201178 【主要元件符號說明】 1…… .....發光單元 23··.·. _.第三電晶體 2…… •…驅動電路 24..… •…電容 21 ••… …·第一電晶體 25••… …·第四電晶體 22..... •…第二電晶體^IDEAL where 'τ is the current decay rate. Therefore, when the driving unit 1 is attenuated due to aging of the material or a long-term use factor, the current attenuation rate can be compensated by the above-mentioned current attenuation rate, and the compensation method is as follows: ▲ For example, suppose The brightness decay rate of the light-emitting unit 1 is 0.6, and the driving current correction formula of the s-lighting unit 1 is as follows: 100 100- ~a'^〇LE〇...··(F.3) 06 where '7_ is corrected Drive current. According to equation (4), the drive current is proportional to the square of the illuminating voltage. Therefore, the equation (F·3) can be modified as follows. 100 ^'Δν.•...(F.4) 06 13 100- 201201178 Because, And wherein the sum of the illuminating voltages Δν is added to the voltage of the material. · Therefore, the equation (F.4) can be modified as follows: ^data ^peak I ~ 'peak " ^DATA) .....(F·5) im-re Therefore, the illumination unit 1 operates on The debugging mode can be known as the driving current attenuation phenomenon caused by factors such as aging of the material, and the correction equation of the data voltage, so that the driving current attenuation caused by the aging of the light emitting unit can be avoided by the embodiment, resulting in The brightness of the light-emitting unit i is attenuated in synchronization. Finally, the third control signal is set to a low potential, so that the fourth transistor 25 is not turned on, and then the data voltage is input and the first and second control signals are set to be high, so that the pixel circuit is like the first In a preferred embodiment, the compensation mode and the illumination mode are sequentially performed to drive the illumination unit 1. Knowing that the design of the present invention can effectively avoid the critical voltage drift effect of the transistor caused by process variation or long use time, so that the pixel circuit does not affect the luminous efficiency due to the critical voltage drift effect. At the same time, the driving current decay caused by the aging phenomenon of an organic light-emitting diode can be effectively avoided, thereby causing the phenomenon that the luminance of the light is attenuated. In addition, the design of the present invention is rather streamlined, and three to four transistors can be used and the above can be achieved. The purpose, therefore, does not significantly affect the aperture ratio, so the object of the present invention can be achieved. However, the above is only a preferred embodiment of the present invention, and the scope of the present invention can be limited by the fact that it does not limit the scope of the invention, that is, the simple equivalent change according to the scope of the invention and the description of the invention. And modifications are still within the scope of the invention patent. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of a first preferred embodiment of the present invention; FIG. 2 is a timing diagram of the first preferred embodiment; and FIG. 3 is a circuit diagram of a first preferred embodiment of the present invention. . 15 201201178 [Description of main component symbols] 1...... .....Lighting unit 23····. _. Third transistor 2... •...Drive circuit 24..... •...capacitor 21 ••... First transistor 25••...·fourth transistor 22.....•...second transistor
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