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The Role of Sensors in the 21st Century
1.11.11 Max Rated Temperature 21
Max rated temperature is often called the “operating temperature.” It
is the ambient temperature at which the LED light source is installed
and at which it should be maintained. In most cases, this is around
40–50°C, which is comparable to 104 to 122°F. Operating an LED light
source beyond the operating temperature will lower the LED’s life
span, leading to its destruction.
1.11.12 mcd
mcd stands for millicandela. It is used to rank the brightness of an
LED. 1000 mcd is equal to one candela. The higher the mcd number,
the brighter the light the LED emits. The human eye may sense visi-
ble light, as described in Fig. 1.9. The visible light spectra varies
between ultraviolet 350 to red 700 nm (Fig. 1.10). Light between 315
and 380 nm is often called long wave or “black-light.”
400 450 500 550 600 650 700
Human Eye Sensitivity Chart
FIGURE 1.9 Visible light spectra. (See also color insert.)
THE VISIBLE SPECTRUM • Wavelength in Nanometers
400 450 500 550 600 650 700 800
(ultra) Violet Blue Cyan Green Yellow Orange Red Magenta (infra)
FIGURE 1.10 Visible ultraviolet light to red light spectra. (See also color insert.)
