0195136047.pdf

314 DIGITAL BUILDING BLOCKS AND COMPUTER SYSTEMS

On/Off

7404

+5 V

LED

R

Figure 6.2.17Light-emitting diode (LED).

of the liquid-crystal material are straightened out, absorbing the light, and the display appears

black. With no electric field applied, the display appears as a silver mirror because the light is

reflected.

SEGMENTDISPLAYS

Seven-segment displays are the most commonly used numeric display devices, while 10- and

16-segment (starburst) display devices are also available. Figure 6.2.18(a) depicts a common-

cathode seven-segment LED display; Figure 6.2.18(b) shows its internal structure, consisting of

a single LED for each of the segments; and Figure 6.2.18(c) displays the digits by an appropriate

combination of lighted segments. The 16-segment display shown in Figure 6.2.18(d) is commonly

used for alphanumeric data.

(a)

(b)

(d)

(c)

a

a

g

d

f

e

b

c

bcde f g

Figure 6.2.18(a)Seven-segment display.

(b)Internal structure of seven-segment dis-

play.(c)Digits displayed by a seven-segment

display.(d)16-segment (starburst) display.