• Journal of Sensor Science and Technology
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• v.27 no.6
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• pp.357-361
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• 2018

This paper presents an averaging current adjustment technique for reducing the pixel resistance variation in a bolometer-type uncooled infrared image sensor. Each unit pixel was composed of an active pixel, a reference pixel for the averaging current adjustment technique, and a calibration circuit. The reference pixel was integrated with a polysilicon resistor using a standard complementary metal-oxide-semiconductor (CMOS) process, and the active pixel was applied from outside of the chip. The averaging current adjustment technique was designed by using the reference pixel. The entire circuit was implemented on a chip that was composed of a reference pixel array for the averaging current adjustment technique, a calibration circuit, and readout circuits. The proposed reference pixel array for the averaging current adjustment technique, calibration circuit, and readout circuit were designed and fabricated by a $0.35-{\mu}m$ standard CMOS process.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.3
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• pp.205-210
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• 2022

A novel OLED pixel circuit is proposed in this paper that uses only n-type thin-film transistors(TFTs) to improve the luminance non-uniformity of the AMOLED display caused by the threshold voltage variation of an OLED driving TFT. The proposed OLED pixel circuit is composed of 6 n-channel TFTs and 2 capacitors. The operation of the proposed OLED pixel circuit consists of the capacitor initializing period, threshold voltage sensing period of an OLED·driving TFT, image data voltage writing period, and OLED·emitting period. As a result of SmartSpice simulation, when the threshold voltage of·OLED·driving TFT varies from 1.2 V to 1.8 V, the proposed OLED pixel circuit has a maximum current error of 5.18 % at IOLED = 1 nA. And, when the OLED cathode voltage rises by 0.1 V, the proposed OLED pixel circuit has very little change in the OLED current compared to the conventional OLED pixel circuit. Therefore, the proposed pixel circuit exhibits superior compensation characteristics for the threshold voltage variation of an OLED driving TFT and the rise of the OLED cathode voltage compared to the conventional OLED pixel circuit.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.8
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• pp.1-5
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• 2009

A new pixel circuit for Active Matrix Organic Light Emitting Diodes (AMOLEDs), based on the polycrystalline silicon thin film transistors (Poly-Si TFTs), was proposed and verified by SMART SPICE simulation. One driving and six switching TFTs and one storage capacitor were used to improve display image uniformity without any additional control signal line. The proposed pixel circuit compensates an inevitable threshold voltage variation of Poly-Si TFTs and also compensates the degradation of OLED at low power supply voltage($V_{DD}$). The simulation results show that the proposed pixel circuit successfully compensates the variation of OLED driving current within 0.8% compared with 20% of the conventional pixel circuit.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.3
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• pp.279-284
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• 2014

This paper proposes a novel OLED pixel circuit to compensate the threshold voltage variation of p-channel low temperature polycrystalline silicon thin-film transistors (LTPS TFTs). The proposed 5-TFT OLED pixel circuit consists of 4 switching TFTs, 1 OLED driving TFT and 1 capacitor. One frame of the proposed pixel circuit is divided into initialization period, threshold voltage sensing and data programming period, data holding period and emission period. SmartSpice simulation results show that the maximum error rate of OLED current is -4.06% when the threshold voltage of driving TFT varies by ${\pm}0.25V$ and that of OLED current is 9.74% when the threshold voltage of driving TFT varies by ${\pm}0.50V$. Thus, the proposed 5T1C pixel circuit can realize uniform OLED current with high immunity to the threshold voltage variation of p-channel poly-Si TFT.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.881-884
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• 2003

We propose a new pixel structure for Active Matrix OLED (AMOLED). The proposed pixel structure can display full color images by compensating threshold voltage (Vth) variation of driving TFTs. And we obtain an improved contrast ratio(C/R) of higher than 600:1

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.2
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• pp.207-212
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• 2013

A novel pixel circuit that uses only n-type low-temperature polycrystalline silicon (poly-Si) thin-film transistors (LTPS-TFTs) to compensate the threshold voltage variation of a OLED driving TFT is proposed. The proposed 6T1C pixel circuit consists of 5 switching TFTs, 1 OLED driving TFT and 1 capacitor. When the threshold voltage of driving TFT varies by ${\pm}0.33$ V, Smartspice simulation results show that the maximum error rate of OLED current is 7.05 % and the error rate of anode voltage of OLED is 0.07 % at Vdata = 5.75 V. Thus, the proposed 6T1C pixel circuit can realize uniform output current with high immunity to the threshold voltage variation of poly-Si TFT.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.543-547
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• 2002

In this paper, we introduce a more improved camera modeling method for linear pushbroom images than the method proposed by Orun and Natarajan(ON). ON model shows an accuracy of within 1 pixel if more than 10 ground control points(GCPs) are provided. In general, there is high correlation between platform position and attitude parameters but ON model ignores attitude variation in order to overcome such correlation. We propose a new method that obtains an optimal solution set of parameters without ignoring the attitude variation. We first assume that attitude parameters are constant and estimate platform position's. Then we estimate platform attitude parameters using the values of estimated position parameters. As a result, we can set up an accurate camera model for a linear pushbroom satellite scene. In particular, we can apply the camera model to its surrounding scenes because our model provide sufficient information on satellite's position and attitude not only for a single scene but also for a whole imaging segment. We tested on two images: one with a pixel size 6.6m$\times$6.6m acquired from EOC(Electro Optical Camera), and the other with a pixel size 10m$\times$l0m acquired from SPOT. Our camera model procedures were applied to the images and gave satisfying results. We had obtained the root mean square errors of 0.5 pixel and 0.3 pixel with 25 GCPs and 23 GCPs, respectively.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1745-1747
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• 2000

TFT-LCD simulator, PDAST(Pixel Design Array Simulation Tool) could simulate the effect of the variation on the pixel characteristics. Since feed-through voltage in TFT-LCD can be a serious problem to pixel voltage characteristics, it should be compensated. It is applicable to various kinds of TFT-LCDs and can be used to calculate the spontaneous part of common electrode voltage accurately. Also, PDAST can estimate pixel voltage according to various inversion methods. It allows high-speed calculation and the information obtained from this study could be utilized to design the larger area and finer image quality panel.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.399-402
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• 2006

A new voltage-scaled compensation pixel which employs 3 p-type poly-Si TFTs and 2 capacitors without additional control line has been proposed and verified. The proposed pixel does not employ the $V_{TH}$ memorizing and cancellation, but scales down the inevitable $V_{TH}$ variation of poly-Si TFT. Also the troublesome narrow input range of $V_{DATA}$ is increased and the $V_{DD}$ supply voltage drop is suppressed. In our experimental results, the OLED current error is successfully compensated by easily controlling the proposed voltage scaling effects.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.901-904
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• 2005

A novel active matrix organic light diodes (AMOLEDs) voltage-programming pixel structure with current-correction method is proposed for largesize and high-resolution poly-Si AMOLED panel applications. The HSPICE simulation results shows that the maximum error of emission current in proposed pixel is 1.536%, 2.45%, and 2.97% with the ${\pm}12.5%$ mobility variation and ${\pm}0.3V$ threshold voltage variation for 30-, 40-, and 50-inch HDTV panels, respectively.