Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Heilmeier displays

Figure 1. Operational principle of a dichroic display (Heilmeier display). Figure 1. Operational principle of a dichroic display (Heilmeier display).
With regard to the dye-related parameter measurements, the dye concentration is usually kept at about 0.5-2%, depending on its absorption coefficient. For azo dyes the dye concentration is about 0.25-1% for dye doped TN, about 2-4% for Heilmeier displays, and about 2-5% for phase change displays. The cell thickness is usually about 5 pm for dye-doped TN at the first Gooch Tarry minimum [ 15,16,88], about 7-10 pm for dye-doped TN at the second Gooch Tarry minimum [15, 16, 88], about 5-15 pm for Heilmeier, and about 10-20 pm for phase change dichroic displays. Usually, the dye concentration is increased by a factor of about 1.5-2 when anthraquinone dyes are used instead of azo dyes, as anthraquinone dyes have less absorbance than azo dyes. Sometimes combinations of azo and anthraquinone dyes are used [16, 54]. [Pg.1248]

Figure 4. Threshold characteristic of Heilmeier display compared to those of a TN and a dye-doped TN display. The transmittance of the Heilmeier, dye-doped TN, and TN displays are 16.0%, 26.7%, and 35.5%, respectively. Operating voltage, 10 V. Figure 4. Threshold characteristic of Heilmeier display compared to those of a TN and a dye-doped TN display. The transmittance of the Heilmeier, dye-doped TN, and TN displays are 16.0%, 26.7%, and 35.5%, respectively. Operating voltage, 10 V.
The threshold characteristic of Heilmeier displays and that of TN displays having the same polarizer and host liquid crystal are plotted in Fig. 4. The figure shows that the... [Pg.1257]

With increasing dye concentration c, the contrast ratio of the Heilmeier display increases and its transmission decreases... [Pg.1257]

Figure 7. Threshold characteristics of Heilmeier displays with 0° and 90° twisted homogeneous alignments. Figure 7. Threshold characteristics of Heilmeier displays with 0° and 90° twisted homogeneous alignments.
The 180° twisted Heilmeier displays show switch-off behavior similar to r-cells. It takes a long relaxation time to return to the quiescent state after a very fast decay to an intermediate level. This long relaxation is undesirable, and a 180° Heilmeier shutter can function reasonably only after using a holding voltage similar to that of r-cells. [Pg.1260]

As predicted from theory, the order parameter has a dramatic impact on the contrast ratio (Fig. 11). The order parameter of the dye is the only parameter that increases both the contrast ratio and the transmission simultaneously. Figure 11 shows that for a good Heilmeier display the dichroic order parameter should be as high as possible (preferably >0.75). [Pg.1260]

Figure 10. Effect of cell gap on the threshold characteristic and contrast of a Heilmeier display. The trans-mittances of cells with 5, 8, and 11 im cell gaps are 23.6%, 20.0%, and 16.0%, respectively. Operating voltage, 10 V. Figure 10. Effect of cell gap on the threshold characteristic and contrast of a Heilmeier display. The trans-mittances of cells with 5, 8, and 11 im cell gaps are 23.6%, 20.0%, and 16.0%, respectively. Operating voltage, 10 V.
The contrast ratio of a Heilmeier display is highly dependent on the polarization effi-... [Pg.1262]

For monochrome applications, one can either put a monochrome color filter inside the cell or use monochromatic back-lighting. For Heilmeier displays, there is another way to get a monochrome display by using monochromatic pleochroic dyes [26]. For full-color display, color filters must be used. Heilmeier displays exhibit better color performance than TN displays, as the chroma-ticity of the pixels does not change much at large viewing angles. [Pg.1262]

Heilmeier displays can be multiplexed only for low levels, as the threshold characteristic is not sharp enough for high level multiplexing. The 90° twisted geometry provides... [Pg.1262]

To get the best results with dye-doped TN displays the liquid crystal fluid must have low viscosity, appropriate dielectric anisotropy, and birefringence. The dyes must have all the advantages already discussed in the Sec. 3.4.8 on Heilmeier displays. [Pg.1265]


See other pages where Heilmeier displays is mentioned: [Pg.777]    [Pg.935]    [Pg.965]    [Pg.1248]    [Pg.1254]    [Pg.1256]    [Pg.1256]    [Pg.1256]    [Pg.1257]    [Pg.1257]    [Pg.1257]    [Pg.1258]    [Pg.1258]    [Pg.1259]    [Pg.1260]    [Pg.1262]    [Pg.1262]    [Pg.1263]    [Pg.1265]    [Pg.1275]    [Pg.1382]    [Pg.1490]    [Pg.2018]    [Pg.2021]    [Pg.2021]    [Pg.2022]    [Pg.2024]   
See also in sourсe #XX -- [ Pg.740 , Pg.745 ]




SEARCH



Cell Heilmeier displays

Color Heilmeier displays

Contrast Heilmeier displays

Multiplexing, Heilmeier displays

Polarizers Heilmeier displays

Transmission Heilmeier displays

Viewing Heilmeier displays

© 2024 chempedia.info