ANALOG PEN TRACKING ON A CATHODE RAY TUBE DISPLAY DEVICE

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP81-00120R000100020036-6
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 12
• Document Creation Date: December 20, 2016
• Document Release Date: December 4, 2003
• Sequence Number: 36
• Content Type: CONT

Approved For Release 2007/09/21 : CIA-RDP81-00120R000100020036-6 3,505,561
Patented Apr. 7, 1970
3,505,561
ANALOG PEN TRACKING ON A CATHODE
RAY TUBE DISPLAY DEVICE
John E. Ward, Lexington, and William D. Stratton, South
Acton, Mass., assignors to Massachusetts Institute of 5
Technology, Cambridge, Mass., a corporation of
Massachusetts
Filed Feb. 14, 1967, Ser. No. 616,093
hat. Cl. H01j 29/78
U.S. Cl. 315-18
ABSTRACT OF THE DISCLOSURE
Pen tracking apparatus for use with a computer-driven
cathode-ray tube display is described. A pattern of beam
spots on the cathode-ray tube centered about the pre-
viously determined center of the pen is within the field of
view of the pen. The amplitude of the pen response to
each of these spots is compared to determine in what
direction the center of the spots must be moved in order
to coincide with the pen center.
The invention herein described was made in the course
of a contract sponsored by the U.S. Navy, Office of Naval
Research.
BACKGROUND OF THE INVENTION
Many modern digital computer systems contain dis-
play equipment capable of facilitating the insertion of
graphical material into memory. One such technique em-
ploys "pen tracking," a term used to denote the ability to
control the electron beam of a cathode ray tube with an
external "writing" device. Graphical information can be
inserted using a light pen as the writing device. The ,rse
of a light-sensitive pen in this .manrerjs..an_established
fechmgtue-Tor "-guidrng file motion of a_CRT beam.
T ough the eraekuig process, the pen controls the posi-
tion of the electron beam by sensing the light output of
the phosphor excited by this beam. To furnish a sketch
to the computer, the display console is placed-in the
tracking mode and the operator "draws" on the face of
the CRT -with the light pen._The coordinates of the_.path
descirbcTby tTie n are-retained by. the. computer to per-
mit contrmious display of the material being sketched.
-ht-a particular prior art display equipment, pen track-
ing is accomplished digitally by logic within the display
console itself. A light pen controls the position of the
electron beam, and beam horizontal and vertical coordi-
nates are stored in registers within the console. These reg-
isters are regularly sampled by the computer. Hardware
implementation of the tracking operation in the display
console frees the computer from performing this neces-
sarily repetitive chore of tracking. In this prior art sys-
tem, when in the tracking mode of operation, the scope
display is interrupted every 10 milliseconds and a track-
ing cycle of approximately 1 millisecond duration is used
to update pen position (a 10-millisecond interval between
tracking cycles is about an upper limit if the beam is not
to be lost when the pen is moved rapidly across the scope
face). The tracking cycle consists of the generation and
display of a tracking pattern centered at the last known
position of the light pen as determined during the pre-
vious tracking cycle. Recalculation of present pen posi-
tion is accomplished using the response of the light pen
to this pattern. The tracking pattern is a small cross con-
sisting of 32 points of light drawn on the CRT by the dis-
play console line generator. The points are plotted one at
a time, starting at the center of the pattern, and incre-
menting out to describe the arms of the cross.
The light pen consists of a photoconductive sensor and
associated electronics (one type of pen consists of a
photo-multiplier tube and threshold detector, with a fiber-
optic cord linking the pen and photomultiplier). When
positioned over the tracking pattern described above, the
pea yields an output pulse for each illuminated point of
the. cross Which falls within its field-of-view. The console
logic counts the points seen on each of the four arms of
the cross and recalculates present pen position from this
digital information. This position serves as the center of
the new tracking cross to be generated in the next tracking
cycle. The cycle takes approximately 1 millisecond to
complete, hence, occupies about 10 percent of the total
display time.
The time required for completion of a tracking cycle
is limited by the phosphor response of the scope. Cathode
ray tubes used in computer display are rewritten 30 times
per second, or less, and must have a persistent phosphor
in order to reduce flicker to tolerable level. Due to this
light persistence, it has been found necessary that a
blanking interval of about 14 microseconds exist between
successive illuminated points of the cross if the pen is to
make a reliable "seen"/"not seen" decision. With 64
points being illuminated in one cycle (i.e., each of the 32
points of the cross is illuminated twice: once on the out-
ward trace of the arm, and again when returning to the
center), the resulting total pattern generation time is about
1 millisecond. This represents a considerable portion of
the total time available for display. As each additional
console is added to the same tracking system, operating
on a time-shared basis, an additional 10 percent of dis-
play time is required, and the amonut of potential display
time being absorbed by the tracking operation becomes of
considerable concern. The problem, then, can be very
succinctly stated: the time required by the present digital
technique for light pen tracking is excessive. A faster
method is needed for updating the position of a pen mov-
ing over the face of a display console.
SUMMARY OF THE INVENTION
This invention is an "analog" pen-tracking technique
which requires a considerable smaller tracking cycle time
than the digital system described earlier. Digital tracking
operates on a points-seen-or-not-seen basis, and a large
number of tracking pattern points are necessary to achieve
positional accuracy. The analog method differs from this
in that the amplitudes of the pen responses to a small
number of displayed points convey the required positional
information. Rather than counting the total number of
points whose responses exceed a preset threshold level,
the amplitudes of the pen responses from only four points
of light on the CRT are compared to provide updating of
pen position.
Basic operation may be explained as follows. Initially,
assume that the pen 55 is placed against the CRT 56
face and held in a fixed position while a point of light
(the electron beam 57) sweeps past. If the output signal
of the pen is plotted as a function of beam position, a
curve such as that shown in FIG. 1 is obtained, the exact
shape depending on the pen optics. If instead, the electron
beam is deflected incrementally so as to generate two
points of light in the vicinity of the pen as in FIG. 2,
with point 1 displayed first, followed by point 2, two
corresponding pen output voltages El and E2, result. The
difference between these D-C amplitudes, E1-E2, provides
a measure of the distance separating the pen center from
the midpoint of the line joining the two displayed points.
Only when the quantity E1-E2 is zero will the two points
be symmetrically centered about the pen.
An analog tracking pattern can consist of four points
as in FIG. 3. Point 1 is illuminated first, followed by
points 2, 3, and 4. With a pen placed over this pattern,
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 Approved For Release 2007/09/21 : CIA-RDP81-0012OR000100020036-6
the horizontal 3 4
pair of points 1, 2 provides a horizontal the X pen-position register 60 and the Y register (not
error voltage, JEh, and the vertical pair, AEv. Convert- shown) (35 ?sec. for a system that was constructed), the
ing these orthogonal difference voltages to error distance horizontal error is available in digital form in 25 ?sec.,
(specifically, increments of distance along the horizontal and the vertical error (not shown) in 35 ?sec. Another
and vertical axes of the CRT face), and adding them to 5 35 ?sec. must then be allowed for the display to return to
the coordinates of the pattern center, establishes the posi- the X, Y positions as determined by the computer 61 it
tion of the pen. This is accomplished by converting the was at when interrupted by the tracking cycle. Thus, the
error voltages to digital code (with appropriate scaling) total cycle time for tracking is 105 ?sec., as compared with
and adding them to the digital coordinates of the pat- 1 msec. for the prior art digital method.
tern center, moving the cross center to this new position 10 The main deflection system comprises the magnetic
centers it about the axis of the pen. Repeating this "track- beam deflection circuitry 77 (for the horizontal deflcc-
ing cycle" at periodic intervals would permit the cross, tion direction) together with its analog input voltage from
hence the CRT beam, to follow a pen moving over the D/A converter 78. The input to converter 78 will be
scope face. The time interval between tracking opera- either a horizontal digital position signal X from com-
tions is utilized to display the graphical material being 15 puter 61, when information is being presented on the
described by the pen. face of CRT 56 from the computer storage; or the input
to converter 78 will be X register 60, the last pen-posi-
BRIEF DESCRIPTION OF THE DRAWINGS tion, when the system is in the pen track mode of opera-
FIG. 1 is atypical pen amplitude response curve. tion. When in the pen track mode of operation gate 79
FIG. 2 shows the analog voltage developed in the pen 20 will be in the "on" position during the time interval
from only two illuminated points. represented by waveforms F+A?B+C+D. When not
FIG. 3 shows the analog tracking pattern of the illumi- in the pen tracking mode gate 80 will be gated ` on" by
Hated points on the face of a cathode ray tube. the complement of these waveforms so that the input X
FIG. 4 is a functional block diagram of the analog from computer 61 will be applied to D/A converter 78.
pen tracking system. 25
FIG. 5 is a block diagram of the circuitry which gen- GENERATION OF THE TRACKING CROSS
erates the four-point pattern for analog tracking.
FIG. 6 is a block diagram of the circuitry for processing
the analog difference voltage in one channel, the hori- At the
-po ti ng e of ing eaegisterr t60 is cycle, the ietormytde-
zflntal. 30 in the pen-position register 60 is used to magnetically de-
FIG. 7 is atiming diagram of the voltages at selected fleet the blanked electron beam to the position of the pen
points the aitiming of FIGS. 5 and 6. as determined by the previous tracking cycle. The tracking
cross is developed using electro static deflection G, H to
DESCRIPTION OF THE PREFERRED further deflect the beam slightly about this position, first
EMBODIMENT 35 to the right, then left, up, and down. At each position,
an unblanking pulse is applied and a point of the cross is
As shown in FIG. 4, the pen tracking circuits consist formed.
of two basic parts: the tracking pattern generator 41, and The block diagram of the tracking pattern circuitry is
the pen-signal processor 42. The tracking pattern genera- shown in FIG. 5. The associated waveforms are shown
tor 41 provides synchronized horizontal G and vertical H 40 in the timing diagram of FIGURE 7. Initially, the pulse
deflection signals and intensification signals J to plot the E starting the tracking cycle is used to trigger delay unit
four-point tracking pattern. It also provides timing pulses 63 to provide a 35 microsecond delay F, necessary to
A-D to the pen-signal processing circuits 42. provide settling time for the magnetic deflection mode
The horizontal (right-left) deflections occur first, and 64. The trailing edge of this delay pulse F starts the
the right El and left E2 pen-amplitude samples are stored generation of the cross. Four deflection voltages A, B,
in sample-and-hold circuits 70, 71 as waveforms N, O. 4i
After a delay C and D symmetrical about zero volts, are generated by
(to allow for transients to subside), the four monostable multivibrators (one-shot MV's 51, 52,
difference amplifier 58 yields the horizontal error voltage 53, 54). These signals are combined, in pairs, in units
R, which is converted to digital binary code T and loaded 65, 66 to obtain the required horizontal G and vertical H
into the AX register 59 of the display system in prepara- 50 deflection voltages, and are then amplified and coupled
tion for updating the horizontal pen position register 60. to electrostatic deflection plates of CRT 56. After each
FIGURE 4 indicates that the tracking system has an of the four sequential deflection plate voltages has
identical vertical channel which receives its inputs C, D achieved its steady state, unblanking pulses J are applied
slightly later than the horizontal channel (i.e., when the to intensity modulate the electron beam of CRT 56 and
vertical deflections occur). Alternatively, one channel can 55 the corresponding point of the cross is illuminated. Pulses
be used for both horizontal and vertical error measure- J are obtained from the leading edge of pulses A-D
ments if the vertical deflections are delayed until the hori- after shaping in combining unit 67 to provide pulses I
zontal coding operations are completed. This would take which are then delayed in monostable MV 68 before
longer, but save on equipment. The remainder of this triggering monostable MV 69.
discussion assumes a parallel system. S0 To accomplish the above cross generation, the four
Note that since the signal at the input to the analog-to- deflection one-shots 51-54 are connected in cascade, the
digital converter 62 is an error signal denoting how far trailing edge of the output of each circuit serving to trig-
the pun moves between tracking cycles, only a few binary ger the following unit.
digits (bits) are needed in the analog to digital (A/D) The leading edge of each output pulse A-D is used
converter 62, irrespective of the total resolution of the 65 to initiate a delay slightly greater than the rise-time of the
sp11Y surface. The number of bits and their weighting deflection amplifier (not shown). At. the end of this delay,
d`Pcnd on the pen field-of-view, the tracking cycle rep--ti- the unblanking pulse J occurs. The above sequence of
t.non rate. and the desired maximum pen speed which the events is detailed graphically in the timing diagram of
cy.+arm i5 to follow. They may be varied in accordance FIGURE 7.
'h47 the parameters of a particular display and a par- ; o In addition to generating the required deflection wave-
,Ii o Fen. form A-D the four one-shots also provide four inde-
f the system are shown in the block schematics pendent circuit states which are used to control the
c i tt,y 5 and 6. Circuit waveforms are shown in the gating of the pen output signals. For the horizontal chan-
itcsgr7m of FI
-? t'Ve display has settled to the position specified by -,3 shown in waveforms Land M.
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 Approved For Release 2007/09/21 : CIA-RDP81-0012OR000100020036-6
3)505;56,1 6
SAMPLING AND STORING OF PEN SIGNALS At this point in the analog tracking cycle, the two sam-
0
pling The pen sensor 55 may be the conventional light pen of f capacitors hold amplitudes the pen cn E E1, E2 2 to the the peak two horizontal l points
znts
such as previously described or may be a "beam pen" 1, 2 of the cross. The difference between these ampli-
which relies on capacitive pickup to detect the electron tudes N, 0 is the error voltage specifying the distance
beam itself, rather than the light it creates when it im- 5 separating the center line of pints 1, 2 and the axis of
pinges on the face of the CRT 56. The "beam pen" is the pen 55. and is obtained with the difference amplifier
described in the AFIPS Proceedings-Fall Joint Computer 58. Each sampling capacitor C1, C2 is coupled to this
Conference, 1965, in an article by D. H. Haring. The amplifier through a Darlington-pair emitter follower 76.
desirable feature of the beam pen is that its output is This configuration provides sufficient isolation of the hold
independent of phosphor decay time. An undesirable fea- 10 ing capacitors C1, C2 to prevent excessive discharge before
ture is that the beans pen field-of-view response curve is subtraction occurs.
considerably broader than that of the light pen because Emitter followers 81, 82 couple the outputs of the dif-
the charge generated impingement of the beam can be ference amplifier 58 having waveforms P, Q respectively
detected over an area larger than that occupied by the to diode OR gate 83. One output of amplifier 58 is also
illuminated spot. The difference in outputs Et, E2 for l5
coupled to Schmitt trigger 91 which serves to load the
a given displacement of the pen axis from the center horizontal sign bit of AX register 59. Diode gate 83
line of spots 1, 2 is therefore less for the beam pen couples the positive-going output of difference amplifier
than for the light pen. The beam pen, in a stationary situa- 58 to analog gate 84. Gate 84 remains closed until the
tion, produces a pulse-to-pulse output fluctuation equal output transient of gate 83 has decayed to zero. At this
to approximately ten percent of the D-C output amplitude. 20 time, gate 84 is opened by gate control one-shot MV 85
With the beans pen 55 placed over the tracking cross, which is triggered by the trailing edge of waveform D.
four output pulses K will occur during each track cycle, The output voltage waveform R of gate 84 is coupled to
their amplitudes depending on the proximity of the pen A/D converter 62 through filter circuit 86 comprising an
to each of the cross dots 1, 2, 3 and 4. The first two 25 envelope detector 87 and low pass filter 88. Filter circuit
pulses Ee E2 are used n determine the horizontal pen 86 reduces noise produced by small variations in beam-
position error; the remaining two pulses, the vertical er- pulse amplitudes due to the electron-beam and the CRT
ror. The horizontal and vertical channels of this pen-track- phosphor. Also, since the small signal detected by the pen
ing system are identical in design and performance. After undergoes considerable amplification prior to insertion in
the pen output pulses E1, E2 corresponding to the horn- 30 the tracking circuitry, stray signals picked up in an early
zontal arm of the cross have been processed, an iden- stage can contribute significantly to the output and must
tical procedure is followed with respect to the vertical be filtered to reduce their influence.
arm. The only difference existing between the two chan- The binary bits bo, b1, b2, of digital output T of con-
nels is the final destination of the binary error signal 62 are stored in the AX register 54 together with
generated by each circuit. The horizontal channel loads verter
35 the binary sign bit S. The rinformation egister 5 is transferred
this information into the AX register 59; the vertical through gate 89 to X register 60 after the X and Y track-
this hannel, into the AY register (not shown). In view of ing information has been obtained. The pulse U from load
t duplication, only one channel, the horizontal , is one-shot MV 90 turns on gate 89 for a time sufficient to
described in detail, shift the X information into the X register 60 (only a few
The circuitry required for the processing of the pen 55 40 microseconds). The shift pulse U occurs about 5 micro-
responses E1, E2, to the horizontal arm, points 1, 2, seconds after input signal gating waveforms A-D have
of the tracking cross is shown in block form in FIGURE terminated.
6. The output of the beam pen amplifier 72 is coupled to Although specific embodiments of the present invention
an emitter follower 73 to provide the required current have been depicted, it is obvious that numerous additions
gain and source impedance for the sampling stages 70, 71. and substitutions may be made without departing from
The output of the emitter follower 73 (the pen response 45
the spirit and scope of the invention. Accordingly, the in-
corresponding to each point of the cross) is applied to the vention should be deemed limited only insofar as it is
inputs of the two channels. The horizontal channel, with restrictively defined in the following claims,
which we are concerned here, commences with two What is claimed is:
parallel analog gates 70, 71. During each tracking cycle, 50 1. Pen tracking apparatus of the type comprising a
four pulses K are received from the beam pen. The cathode ray tube,
first two El, E2, are the responses to the horizontal arm means for intensity modulating a beam of electrons
of the cross, the initial pulse corresponding to the right within said tube,
dot 1; the second, to the left dot 2. While the first point a pen responsive to the effect produced by the electron
1 of the cross is being illuminated, and the correspond- 55 beam impact on the face of said tube,
ing beam pen pulse E1 generated, the deflection multi- said pen having an axis,
vibrator one-shot 51 is in its unstable state, producing said pen having an output which diminishes with the
a +10-volt, 5-microsecond wide pulse A. This pulse, in distance between said axis and said beam impact
addition to providing the deflection for the first point of position,
the tracking cross, is used as the control signal L at the 60 means for deflecting said beam in response to a stored
first analog gate 70. Gate 70 is opened for this 5-micro- signal and a second signal,
second duration and permits passage of the first pen out-
means for providing said stored signal to said deflecting
put pulse E1 to hold circuit 75. Potentiometer 74 is means to cause said beam to deflect to the position
initially adjusted to ensure that the maximum amplitude of the pen axis determined during the previous track-
of the pen pulses is less than the gate control signal L 65 ing cycle,
Diode D1 and capacitor C, serve as a peak detector means for providing a sequence of pulsed second sig
and hold circuit 75. When gate 70 turns off, C, is charged nals at the time said stored signal is applied to de-
to the peak amplitude of the first pen output pulse E1. fleet the beam incrementally about its stored pen axis
During the remainder of the tracking cycle, C1 remains position,
essentially charged at its peak value. Performance of the 70 means for providing intensifying pulses to said intensity
second analog gate 71 is identical. One-shot 52 generates modulating means in time coincidence with said
the control voltage N, and hold capacitor C2 is charged pulsed second signals to provide a plurality of beam
to the peak value of the second pen output pulse E2. impingements on said face spaced in time and space
(Similarly, the analog gates of a vertical channel would from each other,
iA "' kA;- rc -neive to snirl beam impingements to
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3,505,501
7
provide a plurality of output signal pulses in se-
quence,
wherein the improvement comprises,
means for determining the difference in amplitude and
sign of said output pulses to obtain an error signal 5
proportional to the position of the axis of said pen
with respect to the non-incrementally deflected beam
position,
means for adding said error signal to said stored signal
to provide a new stored signal corresponding to the 10
actual location of said pen axis to complete the track-
ing cycle.
2. The apparatus as in claim 1 wherein
said sequence of pulsed second signals deflects said
beam in orthogonal directions to provide two points 15
of beam impingement on said face along each
direction,
said pen being responsive to said beam impingements
to provide output signals,
means for determining the difference in amplitude and 20
sign of said output signals from impingement points
along one direction to provide a first error signal,
said stored signal comprising first and second compo-
nent signals each to deflect said beam along one of 25
said orthogonal directions,
said first component signal deflecting said beam along
the same direction as said first error signal,
means for adding said first. error signal to said first
component signal to provide a signal corresponding
to the pen axis position in said one direction, 30
means for determining the difference in amplitude and
sign of said output signals from impingement points
along the remaining orthogonal direction to provide
a second error signal,
means for adding said second error signal to said second 35
component signal to provide a signal corresponding
to the pen axis position in said orthogonal direction.
3. Apparatus as in claim 1 wherein
said deflection means comprises means for deflecting
said beam in a first direction and a second means for 40
deflecting said beam in a second direction,
said pulsed signals comprising a first and second pulsed
signal,
means for applying a first signal to said first deflection 45
means,
means for applying a second signal to said second de-
flection means,
said first signal providing a pair of points of impinge-
ment of said beam on the face of said tube in said 50
first direction,
said second signal providing a pair of points of im-
pingement of said beam on the face of said tube in
said second direction,
wherein the improvement comprises,
means for detecting the amplitudes of the pen responses 55
to said first direction beam impingements,
means for determining the difference in amplitude and
sign of said first direction pen response amplitudes,
means for providing said amplitude and sign of said
first direction amplitude difference to said first de- 60
flection means to deflect said beam along said first
direction toward the axis of said pen,
means for detecting the amplitudes of the pen responses
to said second direction beam impingements,
means for determining the difference in amplitude and
sign of said second direction pen response amplitudes,
means for providing said amplitude and sign of said
second direction amplitude difference to said second
deflection means to deflect said beam along said
second direction toward the axis of said pen.
4. Apparatus as in claim 3 wherein
said first and second directions are orthogonal.
5. The apparatus of claim I wherein
said pulsed second signals deflect said beam about its
stored pen axis position to form a pattern of four
impact points each equally spaced from said stored
pen axis position and from each other,
two of said points lying along a first line,
the other two points lying along a second line orthogonal
to said first line,
means for comparing the amplitude of said pen outputs
produced by said points along said first line to pro-
vide a first error signal,
means for determining the amplitude of the component
of said stored signal which produces the deflection
of said beam along said first line,
means for adding said first error signal to said first line
component,
means for comparing the amplitude of said pen outputs
produced by said points along said second line to
provide a second error signal,
means for determining the amplitude of the component
of said stored signal which produces the deflection of
said beam along said second line,
means for adding said second error signal to said second
line component.
6. The apparatus of claim 1 wherein
said cathode ray tube has a phosphorus coating on its
face,
said electron beam impingement on said phosphor coated
face producing light output,
said pen being responsive to said light output to pro-
vide an electrical output signal diminishing with
distance from the point of light output to the axis
of said pen.
7. The apparatus of claim 1 wherein
said electron beam impingement on said cathode ray
tube face produces an electrical charge at the point
of impact,
said pen having an input responsive to said charge to
provide an electrical output signal diminishing with
distance from the point of impact to the axis of said
pen.
References Cited
UNITED STATES ;PATENTS
3,028,500 4/1962 Wallmark ---------- 250-211
3,089,918 5/1963 Graham .------------ 178-19
3,271,515 9/1966 Harper.
3,337,860 8/1967 O'Hara ------------ 315 -18 X
3,394,366 7/1968 Dye --------------
D. BENNETT, Primary Examiner
B. L. RIBANDO, Assistant Examiner
U.S Cl. X.R.
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 Approved For Release 2007/09/21 : CIA-RDP81-0012OR000100020036-6
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 Approved For Release 2007/09/21 : CIA-RDP81-0012OR000100020036-6
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Approved For Release 2007/09/21 : CIA-RDP81-0012OR000100020036-6
 Approved For Release 2007/09/21 : CIA-RDP81-0012OR000100020036-6
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 Approved For Release 2007/09/21 : CIA-RDP81-0012OR000100020036-6
Jan. 26, 1971 F. FLORET ET AL 3,559,182
SYSTEM FOR TRACING SYMBOLS ON VISUAL INDICATOR
WITH ORTHOGONAL SWEEP
Filed Dec. 20, 1967 7 Sheets-Sheet &
TC
1/F
A U_
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Felix Floret
Jean-Jacques Mayer
Georges Peronneau
INVENTORS,
BY.
~~ss
Attorney
Approved For Release 2007/09/21 : CIA-RDP81-0012OR000100020036-6
 Approved For Release 2007/09/21 : CIA-RDP81-00120R000100020036-6
Jan. 26, 1971 F. FLORET ET AL 3,559,182
SYSTEM FOR TRACING SYMBOLS ON VISUAL INDICATOR
WITH ORTHOGONAL SWEEP
I244a~ 201a 2Z2a 21 al
,.
GATt a 224ta
{ 2ZICLK~
URCI!!
?0,,-
{
_~'~245CL
3
{ 22
248cL 24 Ta
Y X 234 a,
ADDRESS SCRAMBLE 245ct
` 243 CIRCUIT X10.
CHAIM 2421
SLOW
1 TIMER KL
L
''1c24bb
233 l
049 221 b
247 b
I
IL
L
242b
231b
244b .
?245b
1246 u
I TRAi~S inn
G1
J
F-ly 7
Felix Floret
Jean-Jacques Meyer
Georges Peronneau
INVENTORS.
BY 'j? To"
(r Attorney
_ _ J
Approved For Release 2007/09/21 : CIA-RDP81-00120R000100020036-6
 Approved For Release 2007/09/21 : CIA-RDP81-0012OR000100020036-6
Jan. 26, 1971 F. FLORET ET AL 3,559,182
SYSTEM FOR TRACING SYMBOLS ON VISUAL INDICATOR
WITH ORTHOGONAL SWEEP
Filed Dec. 20, 1967 7 Shoots-Sheet 7
2o1(R)
2
1'tETWOR,K I
229 (6) X
II 2z9(~) X
U9.8
Felix Floret
Jean-.Jacques Meyer
Georges Peronnedu
INVENTORS,
BY 0 S" S`
Attorney
35(R)
Approved For Release 2007/09/21 : CIA-RDP81-0012OR000100020036-6