Influence of bending radius on the properties of flexible AMOLED displays

Wang, Qiujun; Zhang, Wenxin; Su, Weiwei; Zhang, Zeyu; Cui, Jing; Zhu, Weiqi; Dong, Mengyue; Ya, SU; Wang, Bo; Fang, Zhang

doi:10.1002/jsid.1090

Cited by 5 publications

(4 citation statements)

References 15 publications

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“…At present, U-shaped full-path folding is adopted by most producers and companies. However, different folding forms are employed gradually in order to reduce the bending internal stress, among which, the water-drop-shaped folding is introduced into the flexible electronics field due to its superior load-bearing capacity of the structure and increased ability to reduce the gap between the two folded screens [30,31]. The water-drop shape means that the shape of the folded flexible screens is like a water-drop, which is shown in Figure 11a.…”

Section: Influence Of the Water-drop Folding Shapementioning

confidence: 99%

Analysis on the Mechanical Behavior of Flexible Screens

2022

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Recently, flexible organic light-emitting devices (OLEDs) have become more and more popular. However, the force distribution and deformation are very complex during the bending process, and it is difficult to analyze the stress and strain by theoretical analysis and direct experiment. In this paper, finite element analysis of the bending model for the flexible screen was performed. For common U-shaped bending, it was shown that the maximum Mises stress increases rapidly as the bending radius decreases, and the redistribution of the tensile zone and the compression zone should be the key to the layer material selection. The results were verified by an imaging experiment. Further, a water-drop-shaped bending mode was analyzed to reduce the risk of structure failure.

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Section: Influence Of the Water-drop Folding Shapementioning

confidence: 99%

Analysis on the Mechanical Behavior of Flexible Screens

2022

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“…Until now, a large number of studies have focused on improving the bending performance of components such as circuit layer [2] , substrate [3] , polarizer [4] , etc. Some scholars have also simulated and optimized the bending mechanism and the bending path [5,6] in order to reduce the deformation that occurs in the flexible screen during the bending process. In addition, in the optimization of the stacked structure of OLED modules, scholars have optimized and simulated the stacked structure based on machine learning [7] and the principle of force balance as well as mechanical principles such as hyperelasticity intrinsic model [8,9] .…”

Section: Introductionmentioning

confidence: 99%

P‐15.24: a Vision‐based Wrinkle Characterization Method for Flexible OLED Screens

Zhang,

Huang,

et al. 2024

Symp Digest of Tech Papers

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Folding screen phones have a larger display area compared to the traditional form of full‐screen phones, providing users with more usage scenarios. However, as the number of folding times increases, the functional layer of the display module will creep and wrinkles will appear on the surface of the folded screen, affecting the display effect of the screen. Current academic research has made progress in the mechanical simulation of folded screens, and surface flatness and contour curvature are used as quantitative characterization methods for simulation calculations. This paper proposes a quantitative characterization method of optical wrinkling for simulation results based on the basic theory of machine vision, by projecting a circular light spot at an angle of 45° to the screen onto the surface of the flexible screen, and observing the degree of aberration of the light spot at an angle of 135° to the screen as a failure criterion. The corresponding spot aberration value is calculated based on the coordinates of the grating, the coordinates of the light source and the position of the observation camera after CAE(Computer Aided Engineering) simulation. After comparing the experimental results with the simulation results, it is found that the simulation agrees well with the experiment. Finally, the two stacked structures of PET(polyethylene glycol terephthalate) and CPI(Colorless Polyimide), which are the covering layers of the screen, are taken as examples to illustrate that the present method can provide relevant clues for the structural design of the OLED(Organic Light‐Emitting Diode) screen, the selection of materials, and the mechanical problems in the bending process.

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“…[24][25][26][27] These characteristic behaviors of OCA are difficult to describe with the conventional elastic and hyperelastic models, and they are rarely mentioned in existing studies. To simplify and facilitate stress analysis of structures containing OCA, there is already a lot of literature adopting isotropic linear-elastic models [28][29][30][31] or incompressible hyperelastic models [11][12][13][32][33][34] for OCA, whereas few studies have systematically investigated its inherent loading rate dependence, anisotropy and certain compressibility under rapid loading.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on the constitutive model of optically clear adhesive films under rapid loading

Huo

et al. 2022

J of Applied Polymer Sci

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The mechanical properties of optically clear adhesive (OCA) films can be anisotropy and viscoelasticity, and they are distinguished from conventional linear elasticity and hyper-elasticity. These properties should be considered to analyze the interfacial stress, which plays an important role in evaluating the failure of a structure containing OCA. Based on well-designed systematical experiments in the material's principal axes, a phenomenological constitutive model of OCA has been proposed in a transversely isotropic and ratedependent form. For the application to large deformation cases, the constitutive model was developed by using true stress and true strain. Results show that the well-known assumption of volume-incompressibility is not appropriate for OCA, and Poisson's ratio can vary with the loading rate and the current strain. Considering that the mono-axial mechanical behaviors along the material's principal axes present strong non-linearity, an incremental threedimensional constitutive model has been developed for finite element method (FEM) implementation. By comparing with traditional isotropic elastic and hyperelastic models, numerical examination results show that the proposed constitutive model can give a more accurate description of experimental stress-strain curves.

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Influence of bending radius on the properties of flexible AMOLED displays

Cited by 5 publications

References 15 publications

Analysis on the Mechanical Behavior of Flexible Screens

Analysis on the Mechanical Behavior of Flexible Screens

P‐15.24: a Vision‐based Wrinkle Characterization Method for Flexible OLED Screens

Experimental study on the constitutive model of optically clear adhesive films under rapid loading

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