A New 4T0.5C AMOLED Pixel Circuit With Reverse Bias to Alleviate OLED Degradation

Lee, Kuei-Yu; Hsu, Yen-Ping; Chao, Paul C.-P.

doi:10.1109/led.2012.2194983

Cited by 14 publications

(12 citation statements)

References 9 publications

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“…Therefore, pixel design for AMOLEDs is very important for obtaining uniform brightness and a large aperture ratio. Many compensation circuits and driving techniques have been proposed to achieve good uniformity in a display [5]- [7]. A conventional circuit is composed of a scan line, a data line, a power (V DD ) line, two TFTs (a switching TFT and a drive TFT) and a capacitor, all of which reduce the light emitting aperture.…”

Section: Threshold Voltage and Ir Drop Compensation Of An Amoled Pixementioning

confidence: 99%

Threshold Voltage and IR Drop Compensation of an AMOLED Pixel Circuit Without a $V_{\rm DD}$ Line

Lee

Jeon

Moon

et al. 2014

IEEE Electron Device Lett.

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This letter proposes a voltage drop by current (IR drop) and threshold voltage compensation pixel circuit, in which the power line is eliminated. The proposed circuit provides a larger fill factor than the conventional one because the circuit does not use a V DD line but instead utilizes the scan line as a power line. The proposed pixel circuit was verified using both circuit analysis and circuit simulations. The proposed circuit could increase the aperture ratio and compensate for the IR drop and threshold voltage variations in active matrix organic lightemitting diode devices, where I and R are current and resistance of the supply power lines. Using the proposed pixel circuit, a large fill factor with both IR drop and threshold voltage compensation was achieved. Index Terms-Active matrix organic light-emitting diode (AMOLED), pixel circuit, threshold voltage compensation, voltage drop compensation.

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Section: Threshold Voltage and Ir Drop Compensation Of An Amoled Pixementioning

confidence: 99%

Threshold Voltage and IR Drop Compensation of an AMOLED Pixel Circuit Without a $V_{\rm DD}$ Line

Lee

Jeon

Moon

et al. 2014

IEEE Electron Device Lett.

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“…The existing methods to extend lifetime degradation mainly focused on external circuit compensation, which requires additional sensor circuits to detect the degradation of OLED . And internal compensation has strict requirements of well‐designed new pixel circuits such as 5T1C or 4T0.5C . Other researches on host material can also extended OLED lifetime by suppressing exciton quenching and strengthening the stability of radical cations and anions .…”

Section: Introductionmentioning

confidence: 99%

“…[18][19][20][21][22] And internal compensation has strict requirements of well-designed new pixel circuits such as 5T1C or 4T0.5C. 23,24 Other researches on host material can also extended OLED lifetime by suppressing exciton quenching and strengthening the stability of radical cations and anions. [25][26][27][28] Luminance degradation estimation is the precondition of OLED lifetime extension 29 without external or internal compensation circuits.…”

mentioning

confidence: 99%

Influence of ambient temperature on OLED lifetime and uniformity based on modified equivalent lifetime detection

Fan

Zhang

2019

J Soc Info Display

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The ambient temperature can affect the OLED heat dissipation and aggravate the luminance degradation. Based on temperature‐related equivalent lifetime detection, a luminance compensation algorithm without internal or external sensing circuits is proposed and the influence of ambient temperature on lifetime and display uniformity is studied. First, the parameters of luminance degradation curves at any ambient temperature are calculated according to the relationship between accelerate degradation factor n and ambient temperature T, which is determined by the measured luminance degradation curves at ambient temperature 25°C, 45°C, and 80°C. Second, luminance compensation is carried out by increasing drive current according to the estimated luminance degradation influenced by temperature. Furthermore, compensation iterations m, compensation goal value Lgoal, and compensation origin value Lorigin are optimized to obtain a better lifetime extension at different ambient temperature. The simulated and experimental results indicate that the lifetime extensions considering the influence of ambient temperature at 0°C, 25°C, 45°C, 60°C, and 80°C are 29.7%, 28.1%, 18.7%, 18.9%, and 11.6%. Meanwhile, after displaying an image of the International Electrotechnical Commission (IEC) 62087 for 90 hours, the luminance uniformity of OLED increase to 96.0%, 94.0%, 97.2%, 97.2%, and 98.6%, which is a significant improvement compared with it of regardless the influence of the ambient temperature.

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“…Currently, there are some methods about image processing to alleviate the uneven luminance phenomena, such as smoothing the high contrast images and moving slightly the static images [4], but these methods can not compensate the pixels which have severe degradation degree. In addition, there are some circuit compensation methods to compensate the pixels which have severe degradation degree by monitoring the luminance of display, but these methods need a complex external circuits [5,6]. Thus, this paper proposes an OLED lifetime improvement method which bases on optimization of luminance compensation with luminance uniformity.…”

Section: Introductionmentioning

confidence: 99%

19.2: OLED Lifetime Improvement Based on Optimization of Luminance Compensation Considering Luminance Uniformity

Wang

Fan

Sun

et al. 2018

Symp Digest of Tech Papers

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Lifetime is one of the vital factors influencing the OLED displays performance. The existing methods mainly focus on the luminance compensation of OLED pixel to improve lifetime while the OLED luminance uniformity is ignored. The proposed method can optimize luminance compensation and improve luminance uniformity without any sensor. In the proposed method, pixel luminance is compensated while the luminance decays to a setting value. Meanwhile, considering the luminance uniformity, the output grayscale of all pixels of OLED are adjusted based on the actual luminance degradation and input grayscale of each pixel. In addition, luminance non‐uniformity index to evaluate the luminance uniformity is calculated according to the setting weight of each uneven block if the block is considered as uneven blocks. The experimental results indicate that the OLED lifetime can be extended by 28% same as previous method under the luminance compensation optimization and luminance uniformity improvement. Moreover, the luminance non‐uniformity based on human visual characteristics can be improved from 58 to 42.

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A New 4T0.5C AMOLED Pixel Circuit With Reverse Bias to Alleviate OLED Degradation

Cited by 14 publications

References 9 publications

Threshold Voltage and IR Drop Compensation of an AMOLED Pixel Circuit Without a $V_{\rm DD}$ Line

Threshold Voltage and IR Drop Compensation of an AMOLED Pixel Circuit Without a $V_{\rm DD}$ Line

Influence of ambient temperature on OLED lifetime and uniformity based on modified equivalent lifetime detection

19.2: OLED Lifetime Improvement Based on Optimization of Luminance Compensation Considering Luminance Uniformity

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