| 摘要 |
PURPOSE: To prevent residual images or the drop of the contrast ratio and to improve display quality by setting theΔn.d value of liquid crystal at a value larger than one obtained from a specified first minimum condition and thereby by making the lower limit of the driving voltage range higher than the threshold value which allows the liquid crystal to be driven. CONSTITUTION: The product, An-d, whereΔn and d are double refraction index and the thickness of liquid crystal layer respectively is set at a value larger than the one obtained from the first minimum condition that is represented by the formula shown where u=πdΔn/θλ,θ: the tortional angle of liquid crystal,λ: the wavelength of light. Consequently a humpy section giving a peak of the transmission curve appears on the right-hand side of the threshold value voltage Vth. Therefore, the initial voltage Vor as the lower limit of the driving voltage region VR is set at the voltage value which maximizes transmittance T. And the upper limit of the driving voltage region VR is set at 7V. By this, the driving voltage region is reduced without lowering the contrast ratio and thereby the delay in the reaction of liquid crystal is prevented.
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