Gooch-Tarry curve

In a twisted nematic display, the cell is constructed with a dAn product close to a point on the Gooch-Tarry curve that provides ideal rotation of light at visible wavelengths, i.e. with a dAn value usually close to 0.55 pm or 1.05 pm. Placed between two crossed polarizing films with their axes aligned with (or perpendicular to) the alignment directions at the cell surfaces, the resulting rotation of the optical plane of pola-... 

Flgure 11. The Gooch-Tarry curve, showing off-state transmission for a 90° twisted nematic cell between parallel polarizers as a function of u-2d AnIX. 

The threshold characteristic of the dye-doped TN display is very similar to that of a TN display (see Fig. 4). The contrast ratio of a dye-doped TN LCD is heavily dependent on the polarization efficiency of the polarizer, and thus polarizers with very high polarization efficiency (>99%) should be used. The threshold and operating voltages also increase slightly with an increase in thickness. The contrast ratio shows a similar effect to the Gooch Tarry curve in TN displays. The contrast ratio has been found to maximize at the first and second Gooch Tarry minima [16, 88]. It has been found that the incorporation of dyes broadens the Gooch Tarry minima [16, 27]. The addition of a small amount of dichroic dye decreases the values of the maxima and increases... 

Figure 2 shows the plot of T u) as a function of M, the so-called Gooch and Tarry curve. For large values of u, the transmitted intensity T(u) drops to zero and the Mauguin limit is fulfilled. Additional intensity... 

Table 1. Necessary birefringence values to fulfill the 1st, 2nd and 3rd minimum condition according to the Gooch and Tarry curve for layer thickness d=6 pm and d=S pm.

Minima of the Gooch and Tarry curve for NB-mode Birefringence, An ... 

Figure 2. Gooch and Tarry curve for a normally black mode operated TN display.

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