Temperature compensated color LCD projector
AssigneeU.S. Philips Corporation
InventorsFranciscus J. M. Wortel, Ingrin E. J. R. Heynderickx, Peter E. Wierenga
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Abstract
In a projection display device based on one or more (twisted nematic) LCDs (4), simple temperature compensation is possible by optimizing the d.Δn value (n) at the maximal operating temperature. The associated transmission/voltage characteristics at different temperatures then extend substantially parallel so that it is possible to compensate for temperature changes by means of a simple voltage compensation.
Claims20
A projection display device comprising at least one liquid crystal display device in a light path for a light beam having a central wavelength λ, said display device having a layer of liquid crystalline material of a thickness d, and of a difference in index Δn between two supporting plates provided with electrodes which define at least one pixel, via which electrodes a voltage of a value y can be applied across the pixel, characterized in that in at least one of the extreme transmission states the product d.Δn of the thickness d of the layer of liquid crystalline material and the difference in refractive index Δn is chosen to be such that d.Δn/λ at the a maximum temperature of use is 0.45-0.50 0.76-0.85 μm, the device being also provided with means for correcting the value of an said applied voltage in dependence on the said temperature.
A projection display device comprising at least one liquid crystal display device in a light path for a light beam having a central wavelength λ, said display device having a layer of liquid crystalline material between two supporting plates provided with electrodes which define at least one pixel, via which electrodes a voltage can be applied across the pixel, characterized in that in at least one of extreme transmission states the product d.Δn of the thickness d of the layer of liquid crystalline material and the difference in refraction index Δn in relation to an intended maximum temperature of use in chosen to be such that (d.Δn)/λ at the intended maximum temperature of use in between 0.76 and 0.85.
A projection display device comprising at least one liquid crystal display device in a light path for a light beam having a central wavelength λ, said display device having a layer of liquid crystalline material of a layer thickness d and a difference in refractive index Δn between two supporting plates provided with electrodes which define at least one pixel, via which electrodes a voltage can be applied across the pixel, characterized in that d.Δn is chosen to be such that, when cooling the display device from a maximum operating temperature to ambient temperature (20° C.) d.Δnλ/ has a value which passes a value (0.87) corresponding to a first Gooch & Tarry maximum.
Dependencies are inferred from the claim text.