Page 787 - Automotive Engineering Powertrain Chassis System and Vehicle Body

CHAP TER 2 3. 1 Automotive instrumentation and telematics

Fig. 23.1-19 Brightness control range for vacuum-fluorescent display.

amount of ambient light. A photoresistor is a device 23.1.12 CRT
whose resistance varies in proportion to the amount of
light striking it. The display devices that have been discussed to this point
The VFD operates with relatively low power and have one rather serious limitation. The characters that
operates over a wide temperature range. The most seri- can be displayed are limited to those symbols that can be
ous drawback for automotive application is its suscepti- approximated by the segments that can be illuminated.
bility to failure due to vibration and mechanical shock. Furthermore, illuminated warning messages such as
However, this problem can be reduced by mounting the ‘‘Check Engine’’ or ‘‘Oil Pressure’’ are fixed messages that
display on a shock-absorbing isolation mount. are either displayed or not, depending on the engine

ACTIVE
PIXEL

Fig. 23.1-20(a) CRT and associated circuitry.

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