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August 1968 Radio-Electronics
 [Table of Contents]
Wax nostalgic about and learn from the history of early electronics.
See articles from Radio-Electronics,
published 1930-1988. All copyrights hereby acknowledged.
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In August 1968, Radio-Electronics
magazine's "News Briefs" reported on RCA's groundbreaking development of liquid
crystal displays (LCDs), demonstrating how an electric field could turn transparent
liquid crystals opaque - a key step toward flat-panel TVs. The article explained
that these displays, just 0.001" thick and requiring minimal power, could be driven
by integrated circuits and were visible even in bright light, unlike traditional
CRTs. That "Radar Colander" photo looks like an out-of-this-world being - the
lady's hairdo that is, not the metal hemisphere! Additionally, the Supreme Court ruled 7-0 that the FCC had authority to regulate
CATV systems, reversing a lower court decision and impacting cable operations nationwide.
Other highlights included Battronic Truck Corp.'s electric mini-bus (35 mph, 12-passenger
capacity) and the federal government freeing up spectrum between 890–942 MHz for
potential mobile radio use.
News Briefs:
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12/69
News Briefs
 Radar "Colander"
For draining spaghetti it's not. This radar antenna complete with 16,000 holes
is the receiving array for a scaled-down prototype of a new phased array radar system
called ADAR (Advanced Design Array Radar) being built by Hughes Aircraft for the
Air Force. "Colander Girl" Joyce Molkey is holding two of the 16,000 energy feeds
that will extend from the holes.
Clear and Frosted - The only difference between the two windows
is that an electric field has been applied to the one on the right, causing the
liquid crystals to become opaque.
Images are seen by reflection and grow stronger when light shining
on the display is increased. The contrasts with most displays, such as CRT's which
"wash out" under bright light.
Liquid Crystal Displays
A major step toward flat TV screens and similar display devices has been made
by RCA with their announcement of flat, low-power low-cost displays, using a newly
discovered electro-optical effect of liquid crystals. Displays shown recently by
RCA can reproduce any graphic data electronically and can be addressed and driven
by integrated circuits.
Liquid crystals are organic compounds having the mechanical
properties of a liquid - they can be poured - and the regular molecular arrangements
of a solid crystal. RCA Laboratories, Princeton, N.J., determined that certain transparent
liquid crystals turned milky white when exposed to electric fields. When the field
was removed they reverted to their transparent state.
What actually happens to the liquid crystal is shown in the diagram. When an
electric field is set up it creates ions that travel through the crystal material.
These traveling ions then produce a turbulence that causes a scattering of light
which gives the liquid crystal its milky appearance.
 Ions in transit cause disruptions
in liquid crystal that result in turbulence that turns liquid white. The ions are
created when an electric field is applied to the liquid crystals.
To build a display a film of liquid crystal only 0.001" thick
is placed between two sheets of thin glass. The inner face of each glass sheet is
coated with an electrode and at least one of these electrodes is transparent. In
effect, the display is a parallel-plate capacitor in which the liquid crystal acts
as a dielectric. Displays have been built as large as 3 x 4" and there seems to
be no reason to prohibit making substantially larger versions.
Little power is needed to operate the display. The gray scale
varies with the intensity of the applied voltage, which can range from 6 to 60 volts.
Power is 1 mw per square inch, either de or pulsed. Pulsed power is used when motion
is required, the pulses being addressed to individual minute areas of the display
in proper sequence.
FCC Gets Supreme Court OK to Regulate CATV Systems
In a 7 to 0 decision the Supreme Court has upheld the authority of the FCC to
regulate CATV (Community Antenna Television) systems. The Court's statement said
that Congress had given the FCC "broad responsibilities" to control the orderly
development of local TV broadcasting. It went on to say the FCC was right in taking
the stand that "successful performance of these duties demands prompt and officious
regulation" of cable transmission systems.
This decision reversed an earlier ruling by the Court of Appeals and immediately
affects cable companies in Los Angeles and San Diego. However, the ruling is likely
to affect other cable operations throughout the U.S.
 Electric Mini-Bus
Capable of speeds to 35 mph, this 12-passenger electric bus is powered by two
84-volt Exide industrial-type lead-acid cells. The vehicle, made by Battronic Truck
Corp., Boyertown, Pa., uses SCR controls to provide fast starts, smooth operation
and maximum range. Truck versions of this vehicle are also available.
More Spectrum Available
The Federal Government has just announced it is turning back half of the frequency
space between 890 and 942 MHz. This space will be reassigned to nongovernment users
by the FCC. According to Television Digest. TV engineers and broadcasters want to
assign this space to mobile radio. The exact frequencies to be made available are
still to be determined.
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