Eye sensitivity curve

For the red-emitting phosphor (niginally (Zn,Cd)S Ag and Znin> been used. After the prediction that the led emission sh emission around 6l0 nm [2], it took another 10 proposed YVO4 Eu as the red phosph material has already been discussed b later it was replaced by YiOjSiEu wi lattice will reappear in the chapter on X-i proposed Y2(W04>3 Eu because of its 1 The great succes of the Eu luminescei This shows the eye sensitivity curve which a the emission spectra of a Eu -activated phos is clear that the main part of the emission of th>... 

Fig. 34.17. Comparison of the relative spectral energy distribution of Zno.2Cdo.gS-Ag (curve a) and GdjOj-Eu (curve b). The curve denoted by y represents the eye-sensitivity curve (from Bril and De Laat, 1966).

Regarding the maximum of the spectral eye sensitivity curve (A=0.555 pm) this results in a retardation value twist angles =180°-270°. The retardation value is about twice as large as for the 1st minimum condition of a TN-display. For a display with layer thickness d=6 pm... 

Eor LEDs utilized in visible/display appHcations, the human eye serves as the detector of radiation. Thus a key measure of performance is luminous efficiency which is weighted to the eye sensitivity (CIE) curve. The relative eye sensitivity, V (L), peaks in the green at A 555 nm where it possesses a value of 1.0. It drops sharply as the wavelength is shifted to the red or blue, reaching a value of 0.5 at 510 and 610 nm. The luminous efficiency, in units of Im/W, of an LED is given by equaton 11 ... 

They are represented as coordinates in a color plane. The chromaticity coordinates x and y are used to specify the saturation and hue of any color in the CIE chromaticity diagram. See Figure 4 a for illumination D 65. The CIE spectral tristimulus value y (2) corresponds to the lightness sensitivity curve of the human eye. Therefore, a third color variable is specified in addition to x and y, namely the CIE tristimulus value Y, which is a measure of lightness. 

Figure 5.5.10-2 compares the typical putative spectrums based on such a linear analysis, (3, y, p compared to the actual chromophores, Rhodonines 5, 7 9 [with Rhodonine(l 1) shown for completeness. It is not significant in human vision except for aphakic patients.] Hunt describes the (3,y p spectrums as probable sensitivity curves of the three types of cones. He did not discuss any rod spectrum in his figure. The probable sensitivity curves appear to have been normalized individually. The peak in the p spectrum appears to be at a longer wavelength than frequently suggested. However, it is still at too short a wavelength to support the known spectral response of the human eye as illustrated by the Photopic Luminosity Function. 

Fig. 2.9 a Sensitivity curves for the rods (370 nm curve) and cones (445 nm curve—blue 508 nm curve—green 565 nm curve— red, orange, yellow) in the human eye b The 1931 CIE standard observer. 1980, American Chemical Society, Ref. [15]... 

The indirect methods discussed thus far have dealt with measurement of color only as it can be correlated with physical characteristics of materials and the effect of these materials on radiant energy. As has been pointed out, the reflectance spectro-photometric curve describes a property of the material. A change in the reflectance spectrophotometric properties may not always result in a change in visual color. The reason is that color of the object is not an unchangeable characteristic of the object itself, dependent only upon these reflectance properties, but is also dependent upon the quality of the illuminating light and the sensitivity of the observer s eye. Thus the measurement and description of visual color are psychophysical problems... 

Blue is a unique color in that the z curve of Figure 3, related to the eye s blue sensitivity, is much more remote from the X and y curves than the x and y curves are from each other. The consequence of this is that statements about the brightness of a blue phosphor can be highly misleading. This is because the really meaningful figure of merit for a color TV screen is its white field brightness (WFB). This is defined as lumen output divided by total excitation power (P) incident on all three phosphors while they are excited so as to yield a specified white color. That is. 

Figure 2.3 Sensitivities of rods and cones of the mudpuppy (a large aquatic salamander) retina. The graph shows the intensity-response curves, which were measured intracellularly from the retina of a dissected eye. The response is shown as a fraction of the response at saturation. A fit to the data is also shown. Rods are approximately 25 times more sensitive than cones. (Reprinted with permission from Gordon L. Fain and John E. Dowling. Intracellular recordings from single rods and cones in the mudpuppy retina. Science, Vol. 180, pp. 1178-1181, June, Copyright 1973 AAAS).

FIG. 143. Absorption coefficients of some ionic colourants in glass (after Kingery, 1960). The curve of average sensitivity of the human eye is plotted as the dashed line. 

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