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Buckling prevention in a flexible display cell Disclosure Number: IPCOM000011554D
Publication Date: 2003-Mar-04
Document File: 1 page(s) / 26K

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Buckling prevention in a flexible display cell



Bending of a bi-layer flexible display cell such as a liquid crystal display or a polymer or organic light-emitting diode introduces tensile stresses in one substrate (the upper substrate in figure 1) and compressive stresses in the other (lower) substrate.

Figure 1         � � � � � � � � Bending of a flexible display cell.

Figure 2        � � � � � � � � � Buckling of a compressive loaded sample

A compressive loaded sample is sensitive to buckling above a critical (buckling) load (figure 2). The critical load is given as F = cbuckling D/L2, where D is the flexural rigidity of the sample, L is the span length between the force application points and constant cbuckling depends on the clamping conditions.

Buckling may lead to significant cell gap variations in a flexible display cell. Flexible Liquid Crystal Display cells need appropriate cell gap control. Flexible polymer or organic light-emitting diode (polyLED/OLED) cells contain polymer substrates with hermetic coatings. Transparent hermetic coatings are frequently brittle layers of sub-micron thickness. These coatings are quite sensitive to mechanical damage. Buckling within these cells leads to high contact pressures, combined with an eventual frictional movement of upper and lower substrate with respect to each other during bending. This will damage the functional (hermetic) layer. A damaged hermetic coating is no longer hermetic.

Buckling can be prevented by providing spacers within the...