User`s manual

4,291,198
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will be recirculated, e.g., to the screen 13 of the same set
or when that screen will be employed to display data
received from a remote source through the element 109.
The LOCAL option is useful for checking operation of
the set.
Three user-selectable options described up to this
point may seem to overlap, but they serve discrete func
tions. These are the RS/CL, FD/HD, and RM/LOC
options. The RS/CL option is used to select the correct
circuit con?guration 22' or 22" to match the external
facility to which the data portion of set 10 is to be con
nected. The FD/HD option is used to conform proces~
sor program to the operating mode of a host computer
based service. The FD/HD state is set by switch
change or command whichever occurred last. That is,
in full duplex operation the station set keyboard output
is transmitted to the host which echoes it back to con
trol the set display, but in half duplex operation the set
keyboard output is used (through the LOCAL mode)
when available to control the set display and the host
output is used (in the REMOTE mode) to control the
set display as to information originated by the host. [11
either case of course, the display control is exercised
through UART 89, processor 43, and VRAM 59. Fi
nally, the RM/LOC option is available only when the
CL option is in effect and is used to select a correct
circuit con?guration for either independently testing
the station set or implementing display of set transmit
ted data in the half duplex mode of operation.
It can be seen from FIGS. 4-5 that the handset and
associated voice circuits depend upon use of the keypad
15 and processor 43 to establish a voice communication
path. The voice circuits thereafter operate indepen
dently through the voice signal port represented by
connection to circuit 21; and the keypad and associated
data circuits operate independently through the data
signal port represented by connection to circuit 22. The
combination of these discrete capabilities in the single
station set gives new freedom to the set user. For exam
ple, the user while engaged in a voice communication
with another person and using handset 17, can also
engage in a data communication with a host computer
using the keypad 15 and screen 13. The other station set
must be one sharing the same host computer, or their
respective hosts must have data communication capabil
ity. Thus, the host computer, or an aide using the sec
ond set, can keep the ?rst set user informed of additional
incoming voice calls on other lines, and that first user
can respond with desired disposition of such additional
calls. The set user engaged in a voice call simulta
neously interrogates his host computer for such data as
telephone numbers, appointments, or other previously
stored information and update the data. In any case, the
other party in the ongoing voice communication is
unaware of the data communication.
Similarly, if handset 17 is not in use but the set user is
engaged in a meeting with one or more visitors, silent
data messages can be exchanged with the host com
puter; and a visitor that cannot view screen 13 will be
unaware of the message content. The small size of the
set and the recessed screen (as will be discussed) make
this type of private video message operation possible.
Likewise, if the set 10 is powered up while the user is
out of the room, a message can be left on the screen by
a remote caller if the host security arrangements permit.
The host must however keep track of the state of the
screen and store any surplus messages to prevent over
writing of a first message by subsequent messages.
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FIG. 6 illustrates a particular orientation of the hy
brid transformer 76 and the vertical deflection coils 118,
i.e., the de?ection coils operating in the audible fre
quency range, of the cathode ray tube 14 which in
cludes screen 13. Circuit elements are necessarily close
to one another in the illustrated station set. It was found
that the cathode ray tube vertical oscillator coil and
deflection yoke produced strong magnetic ?elds which
injected noise into the circuits in which the hybrid coil
76 was connected. Rather than shield either of those
coils, it was found that the hybrid coil 76 could be posi
tioned to pick up a relatively low level of interference
audible in receiver 72. This is achieved when the hybrid
coil is located so that its mutual inductance with the
combination of the vertical de?ection yoke coil and the
vertical oscillator coil is at or near zero. The most ad
vantageous position was found in the illustrated em
bodiment to be an orientation in which the longitudinal
axis of the straight core on which the coil 76 is wound,
when the core is in a plane parallel to the bottom of the
set, was at approximately a 30-degree angle to the pro
jection of the neck of the cathode ray tube in the plane
of the core. The longitudinal axis of the tube was at an
angle of about 30 degrees to the plane of the bottom of
the set. In that embodiment, the vertical oscillator 115 is
located on the opposite side of tube 14 from coil 76 and
with its coil in approximately the same plane as the neck
of tube 14.
FIG. 7 is a cross-sectional view of the station set base
11 and hood 12 taken on a plane extending vertically
through approximately the center of the display screen
13. All circuit elements except the cathode ray tube and
the keyboard 20 have been omitted to facilitate illustra
tion.
The cathode ray tube is held in place in the housing
by a semirigid rod type support frame 119. Keyboard 20
rests on a rectangular shoulder 120 extending around
the front wall of the base portion 11 and along a part of
the two sidewalls thereof (only the front wall portion of
the shoulder 12!) is shown in FIG. 5). The keyboard 20
is made large enough to press against the screen 13 of
the cathode ray tube for slightly de?ecting the frame
119 rearward (to the left as illustrated) when the key
board is in place in the illustrated rest position. This
wedges the keyboard 20 into position between the front
wall of base portion 11 and the lower edge portion of
the screen 13, which portion is also simultaneously
masked in a partial bezel fashion by the left-hand edge
(upper edge in FIG. 1) of the keyboard.
An inverted-u-shaped bezel 115, advantageously
formed of a flexible plastic such as polyvinylchloride, is
further shaped to give the sides and bottom of the U an
interior bevel effect so that the bezel cooperates with
the sloping keyboard 20 to complete an inwardly slop
ing frame masking the edges of screen 13. The ends of
the inverted-u bezel 115 rest on the top face of keyboard
20 while the interior edges of the bezel bear against
screen 13. The hood 12 is assembled after the tube and
bezel are in place by pressing opposite sides of the hood
toward each other and lowering the hood over the
bezel and the tube until a downwardly extending index
finger 121 engages an aperture in a lip 122 at the back of
the base portion 11. A lip 124 around the front opening
of the hood holds bezel 115 against screen 13. Then the
sides of the hood are relaxed to allow latching ?ngers,
such as the ?nger 123, to engage a cooperating recess
126 in the sidewall of the base portion 11. The keyboard
is then inserted by pressing the left edge, as shown in