Active-matrix Electrophoretic Display Research Articles

38.4: 6‐inch Rollable Active‐Matrix Electrophoretic Display Driven by Organic Thin‐Film Transistor

AbstractA 6‐inch rollable active‐matrix electrophoretic display driven by organic thin‐film transistor is demonstrated by using solution and photolithography processes. All process temperature are kept below 120 degree C. Pixel OTFT devices exhibit an average mobility of 0.6 cm2/Vs and good reliability. The rollable EPD prototype has thin (125um) and light (14g) features. The minimum rolling diameter can reach 25 mm.

A controller design for high-quality images on microcapsule active-matrix electrophoretic displays

Active-matrix electrophoretic display (AMEPD) is commonly used for the applications of smart handheld reading devices such as e-books and e-news. This paper presents a new reduced waveform lookup table storage method that reduces the associated lookup table by approximately 2n (n is the number of gray levels employed) times the conventional one. The paper also proposes a driving method for image display. The method provides high-speed performance for image display and also effectively eliminates the image residue, achieving high image quality. The prototyped controller was connected to a 6” AMEPD panel, whose excellent display quality demonstrated the effectiveness of the proposed controller design.

A controller design for micro‐cup active‐matrix electrophoretic displays

Abstract— The active‐matrix electrophoretic display (AMEPD) has been commonly used for the applications of smart handheld reading devices such as e‐books and e‐newspapers. This paper presents a controller IC design for the AMEPD backend system which reduces the total hardware cost compared to that of the conventional design. By contrast, this study also provides a driving method for image displays. The prototyped controller is connected to a 6‐in. AMEPD panel, and good display quality has demonstrated the effectiveness of the proposed controller design.

Compact Polyimide-Based Antennas for Flexible Displays

In this paper, we present two compact ultra thin and flexible printed monopole antennas intended for integration with flexible displays, such as flexible organic light-emission displays (FOLEDs) and active matrix electro-phoretic displays (AM-EPDs). The proposed antennas are designed to provide Wireless local area network (WLAN) and Bluetooth connectivity for flexible displays. The first design is a dual band antenna operating at 2.45 GHz and 5.2 GHz while the second is a single band antenna operating at 2.4 GHz. Both antennas were printed on a Kapton polyimide-based substrate with dimensions (35 mmt25 mm) and (26.5 mmt25 mm) for the dual and single band respectively. Antenna properties, such as gain, far-field radiation patterns, scattering parameter S11 are provided. Moreover, the effect of folding/bending was performed experimentally on both designs to study its influence on the antennas performance. The proposed compact, thin and flexible designs along with antennas characteristics are perfectly suitable for integration into flexible displays for WLAN and Bluetooth connectivity.

A Controller Design for Color Active-Matrix Displays Using Electrophoretic Inks and Color Filters

Color active-matrix electrophoretic display (AMEPD) is the inevitable trend for the applications of smart handheld reading devices such as E-books and E-news. This paper presents a normalized RGB color filter (CF) design which achieves 15.66% full white reflectance, 10.80 contrast ratio, and 5.01% of National Television System Committee (NTSC) color gamut. In addition, a new storage method with a minimized lookup table that significantly reduces the data storage space by 2n times of the conventional one, where n is the number of gray levels. The prototyped controller has connected to a 6” color AMEPD panel covered with the normalized RGB structured CF, and an excellent display quality has demonstrated the effectiveness of the proposed controller design.

A Controller Design for Micro-Capsule Active Matrix Electrophoretic Displays

The active matrix electrophoretic display (AMEPD) has been commonly used for the applications of smart handheld reading devices such as e-books and e-news. This paper presents a new minimized waveform lookup-table that significantly reduces the table size of the conventional one by (2n) times, where n is the number of gray levels. The smaller size implies that more driving waveforms can be stored. The prototyped controller has connected to a 6-in AMEPD panel, and an excellent display quality has demonstrated the effectiveness of the proposed controller design.

P‐62: An Integrated Back‐end System Design for Active Matrix Electrophoretic Display

AbstractThe active matrix electrophoretic display (AMEPD) has been commonly used for the applications of smart hand‐held reading devices such as E‐books and E‐news. However, due to facing other competitors in this market, the hardware cost of the back‐end system and panels are necessary to reduce. This paper presents an integrated back‐end system design for AMEPDs. A controller IC which integrates T‐CON and CPU functions has been developed. It also has the function of the 16 multi‐pipeline update design. The new controller IC makes lower total system hardware cost, better ability of lower power states, high flexibility in panel resolution, signal timing of source/gate drivers and Vcom. It has significantly expanded system integration and functionality features. In addition, the integrated power IC which supports output voltages of source/gate drivers and Vcom is proposed. Therefore, the hardware cost of the power system is much lower.The implementation of the new controller and power ICs is verified by the 6″ AMEPD panel produced by Chunghwa Picture Tubes, LTD (CPT). It is in use with the single‐chip structure which integrates the functions of source and gate drivers. The resolution can achieve 800 × 600 (167dpi). Depending on our integrated AMEPD back‐end system, the testing results of our 6″ AMEPD panel performance can reach 48% reflectance, 16 gray level and 8:1 contrast ratio.

P‐192: Novel Flexible Photo Sensing Pixel for Large Size Electrophoretic Display with Pen Writing Function

AbstractIn this paper, we proposed a novel photo sensing pixel circuit for a large‐area flexible e‐reader utilizing an active matrix electrophoretic display (AMEPD). The photo sensing pixel consists of only 2 amorphous Si:H (a‐Si:H) transistors to achieve light sensing, pixel switching and signal amplification functions without extra driving signals. The pixel output signal is up to 2V under illuminations of a common LED laser pointer. No degradation of the pixel output performance is observed after bending of more than 5000 times under 2cm curvature radius.

26.3: High Integration and Functionality Controller for Active Matrix Electrophoretic Display

AbstractA high integration and functionality controller IC for Active Matrix Electrophoretic Displays (AMEPDs) has been developed. The new controller architecture is the single‐chip of the AMEPD back‐end system which makes lower total system hardware cost and complexity, better ability of lower power states, high flexibility in panel resolution, signal timing and DC/AC Vcom operating mode used for microencapsulated and micro‐cup electrophoretic display. The new controller IC has significantly expanded system integration and functionality features. It is suitable for the display controller IC of commercial AMEPD back‐end system. The implementation of the new controller IC is examined in use with 6″ and 8″ AMEPD panels produced by Chunghwa Picture Tubes, LTD. (CPT). Furthermore, the resolution of the 6″ and 8″ AMEPD panels can achieve 800 × 600 (167dpi) and 1024 ×768 (160dpi). Depending on our single‐chip AMEPD back‐end system, the testing results of our AMEPD panel performance can reach 48% reflectivity, 16 gray level and 8:1 contrast ratio.

P‐103: Performance Active Matrix Micro‐Cup Electrophoretic Display

AbstractChunghwa Picture Tubes, LTD. (CPT) has successfully developed the 6″ and 8″ Active Matrix Electrophoretic Display (AMEPD) panels with the micro‐cup structure. The characteristics of AMEPDs comprise reflective paper‐like appearance, readability, portability, affordability, ultra‐low power consumption and high resolution. Therefore, the AMEPD panel is suitable for portable handheld devices such as E‐book readers or electronic news papers. Moreover, the EPD technology with the micro‐cup structure has the advantages of insensitive to pressure suitable for flexible display and easy to mass loss cost manufacture by the roll to roll process. However, the new 30V EPD film with the hexagonal micro‐cup structure has higher reflectivity and contrast ratio than the traditional 15V EPD film with the quadrilateral micro‐cup structure. The main feature of our 6″ EPD panel with the 30V EPD film include 800*600 pixels, 167dpi resolution, 33% reflectivity, 16 gray level and 9:1 contrast ratio. The main feature of our 8″ EPD panel with the 30V EPD film include 1024*768 pixels, 160 dpi resolution, 33% reflectivity, 16 gray level and 9:1 contrast ratio.

Configurable timing controller design for active matrix electrophoretic display

To design various electronic papers, the panel designers may adopt different types of electrophoretic materials and active matrix backplanes for resolution, speed, and contrast ratio considerations. The electrical and optical characteristics are quite different under different design requirements so that a good display timing controller should provide an easy way to modify waveforms accordingly. In this paper, we present a configurable timing controller for active matrix electrophoretic displays (EPD). The design principle of driving waveforms is first discussed and the controller can support all variations of driving waveforms with pulse width modulation. The performance of the controller has been verified by several practical EPD systems.

Predicting Method of Leakage Current in Multiple-Gate Amorphous Silicon TFTs for Active-Matrix Electrophoretic Displays

The large off-state drain-source leakage current of the thin-film transistor (TFT) in active-matrix electrophoretic display (AMEPD) may cause severe crosstalk and long pixel refresh time. Multiple-gate amorphous silicon TFT (a-Si TFT) is a common use to overcome this issue. In this paper, we show that the leakage current of multiple-gate a-Si TFT can be computed from the - characteristics of a single TFT by an analytical current model. The predicted leakage currents show good agreement with the expected values in SPICE simulation. This model is also applicable for the multiple-gate a-Si TFTs used in other high voltage driven devices.

Simulation of Active-Matrix Electrophoretic Display Response Time Optimization by Dual-Gate a-Si:H TFT With a Common Gate Structure

Large off-state drain-source current of the thin-film transistor (TFT) in active-matrix electrophoretic display (AMEPD) pixel leads to dramatic data voltage degradation, which causes severe crosstalk and undesired large response time. In this paper, the leakage current influence on response time is investigated and simulated. A compact model of response time t versus off-state drain-source current <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</sub> is established. The simulation result induces that by reducing <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</sub> the response time can be efficiently shorted. In order to reduce the off-state current, dual-gate amorphous silicon (a-Si:H) TFT with a common gate structure is discussed. Its current regulation mechanism is illustrated, and its fitness for driving the AMEPD pixel is explained. The SPICE simulation results prove that except reducing the crosstalk, dual-gate a-Si TFT can also significantly short the response time by cutting down the off-state current under the operation conditions of AMEPD application, while insignificantly reduces the on-state current.

A flexible 2.1‐in. active‐matrix electrophoretic display with high resolution and a thickness of 100 μm

Abstract— A paper‐thin QVGA, flexible 2.1‐in. active‐matrix electrophoretic display (AMEPD) that features 100‐μm thick and a 192‐ppi resolution has been developed. An LTPS‐TFT backplane with integrated peripheral driver circuits was first fabricated on a glass substrate and then transferred to a very thin (30‐μm) plastic film by employing surface‐free technology by laser ablation/annealing (SUFTLA®). A micro‐encapsulated electrophoretic imaging sheet was laminated on the backplane. A supporting substrate was used to support the LTPS‐TFT backplane. Fine images were successfully displayed on the rollable AM‐EPD. The integrated driver circuits dramatically reduce the number of external connection terminals, thus easily boosting the reliability of electrical connections even on such a thin plastic film.

ディスプレイ―ＩＤＷ’０７を中心に―全印刷法による電気泳動ディスプレイ用１０．５ｉｎｃｈ‐ＶＧＡフレキシブル有機ＴＦＴ背面板

We developed an all-printed flexible organic TFT with a channel length below 10μm and a mobility of over 0.01 cm2/Vs using an offset-based high-resolution printing technique and inkjet printing of small-molecule organic semiconductors. These technologies have been applied to a demonstration of a 10.5-inch VGA flexible active-matrix electrophoretic display driven by an all-printed organic TFT backplane.

Flexible Electrophoretic Display with Inkjet Printed Active Matrix Backplane

A 9.6-inch, 25.7-ppi organic-TFT-driven active matrix display backplane was developed and fabricated by using an effective combination of inkjet printing and vacuum processes. This novel process, which consists of a single photolithography step for forming source and drain electrodes and two inkjet printing steps for forming semiconductor layer and gate electrode, is particularly compatible with flexible plastic substrates. The highest temperature in the process was 80&#xB0;C, and the total processing time required to fabricate the panel was only 30 hours. An active matrix electrophoretic display device was fabricated by laminating an E-Ink Imaging Film on the organic TFT backplane, and was proven to operate stably in the air even without a passivation layer. Thus the effectiveness and adaptability of this hybrid process for e-paper applications was confirmed. The process also enables flexible displays to be produced easily and at low cost. Organic TFT active matrix backplanes fabricated using this process are considered to be viable for display devices used in e-papers, smart cards, and other products with high-volume, low-cost requirements.

62.3: 10.1 inch SVGA Ultra Thin and Flexible Active Matrix Electrophoretic Display

A 10.1 inch SVGA reflective type flexible active matrix electrophoretic displays were successfully fabricated on a thin metal foil substrate. It was developed a new multi-barrier structure in order to use a rough metal foil as display substrate and designed a new TFT array structure for obtaining good performance. The backplane comprises a-Si thin film transistor array fabricated using a conventional TFT manufacturing technologies. The 800×600 pixel display can be driven during extremely bending and measures only 0.3 mm in total thickness and weighs 32.8 grams. This prototype displays have a true paper-like look and feel, with wide-viewing angle and high contrast ratio.

62.2: A Flexible 7.1-in. Active-Matrix Electrophoretic Display

We have developed a flexible 7.1-inch Quad-XGA active-matrix electrophoretic display using SUFTLA™. The whole panel circuitry including 7.3-milion transistors was successfully transferred onto a plastic substrate without damage. Integrating both scan- and data-drivers made it possible that 3-mega pixels are controlled with only 40 signal terminals. The developed panel fulfills major requirements for e-paper including true flexibility, thinness and lightness.

3.1: Invited Paper: Rollable QVGA Active-Matrix Displays Based on Organic Electronics

A 100 μm thin QVGA active-matrix electrophoretic display is produced using organic transistors. The display can be bent to a radius less than 1 cm without any performance loss. Higher contrast and low crosstalk was achieved by addition of a field shield to our backplane.

45.1: System‐on‐Plastic with Organic Electronics: A Flexible QVGA Display and Integrated Drivers

AbstractA flexible 4.7‐inch QVGA active‐matrix electrophoretic display is demonstrated, containing 76800 solution‐processed organic transistors. In the same technology, 32‐ and 120‐stage row drivers are produced with adequate speed to drive a QVGA display. Both the display and the drivers are highly flexible. Bending the display to a radius below 2cm does not result in any performance loss.