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Nov..5, 1946.
_ D, w, PuGsLEY
Filed Nov. 20, 1942
7 // .rrfs
Pig. 2.
inventor“ 2
Donald ‘W. pugsley,
His Attorney.
Patented Nov. 5, 1946
SWEEP omcmr
Donald W. Pugsley, Bridgeport, Conn., assignor
to General Electric Company, a corporation of
New York
Application November 20, 194-2, Serial No. 466,266
2 Claims. (01. 315429)
i2, l3,'and M in Fig. 2. The steeper slopes l2
The present invention relates to a sweep cir
and i3 are used for locating the nearer objects.
The sawtooth waves‘ shown in Fig. 2 are ob
tained from the voltage on a condenser l5 con
nected across the anode l5 and cathode ll of a
_ An object of my invention is to provide a sweep
tube is and in series with a charging resistance
circuit producing a sawtooth wave having its
as connected to a power supply 20. The high and
slope’ adjustable without substantially affecting
low sides of the condenser are respectively con
its’amplitude so thelength of the trace will not
nected to the anode and cathode. The grid 2|
be a?ected by the change in slope.
The novel features which I believe to be char 10 of the tube I8 is connected to the pulse genera
cuit producing sawtooth waves of adjustable
slope for controlling the time scale of the trace
of cathode ray tubes.
acteristic of my invention are set forth with par- '
ticularity in the appended claims. My inven
tion itself, however, both as to its organization
and method of operation, together with further
objects and advantages thereof, may best be
tor 2 which drives the grid positive during each
of the pulses 3a, reducing the impedance of the
tube and causing the discharge of the condenser
I5 through the tube. The drop in condenser
voltage during the pulses 3a, indicated at 22 in
Fig. 2, is determined by the pulse width which is
understood by reference to the following descrip
tion taken in connection with the accompanying
substantially constant. At the end of the pulses
drawing in which Fig. 1 shows a sawtooth sweep
circuit embodying my invention and Fig. 2 is a
the condenser voltage builds up at a rate deter
diagram explaining the operation.
Referring to the drawing, there is shown a
sweep circuit embodying my invention applied to
radio locating equipment having a transmitter
I driven by a pulse generator 2 producing pulse
voltages 3 which cause the transmission of cor
responding pulses of radio waves at the desired
repetition rate over an antenna 4 and pulse volt
3a the grid 2i returns to its normal potential and
mined in part by the charging resistance l9. The
rate of build-up of the charge of the condenser
is also controlled by a tube 23 connected as a
positively biased diode recti?er by having its grid
24 and anode '25 connected through a resistance
26 to a potentiometer 21 across the power supply.
Being connected as a diode, the tube 23 becomes
conducting at a de?nite voltage and is non
conducting below that voltage. The anodes l6
ages 3a which, ashereinafter described control
and 25 are connected by a coupling condenser 28
a sawtooth sweep circuit. Usually (though not 30 large enough to maintain a substantially con
necessarily) the pulses 3 are slightly later in time
stant voltage difference between the anodes.
phase than the pulses 3a. The responses to the
Just before the pulses 3a the condenser I5 is
transmitted pulses, which may be re?ections of
charged to its maximum voltage, indicated at 29
the transmitted pulses or pulses from pulse
in Fig. 2, the diode 23 is conducting, the anode 25
transmission equipment carried by the object to 35 being at a small positive voltage due to the low
be located and excited by the transmitted pulses,
internal resistance of the diode, and the coupling
are conducted from the antenna through a re
condenser 28 is charged to the difference in po
ceiver 5 to the vertical plates 5 of a cathode
ray tube 1 and cause the vertical de?ections 8 and
kential between the anodes l6 and 25. Since the
coupling condenser 28 maintains a constant volt
9 corresponding to the transmitted and received 40 age difference between the anodes I6 and 25, the
sawtooth waves of Fig. 2 represent the voltage of
either anode. During the pulses 3a the grid 2| is
driven positive, reducing the impedance of the
causing a horizontal deflection or trace H . which
tube l8 and causing the discharge of the con
provides a linear time scale coordinating the 45 denser l5. As the condenser discharges, the
transmitted and received pulses so that the dis
voltage of the anode l6 becomes negative with
tance between the de?ections 8 and 9 provides a
respect to its maximum voltage 29, and, due to
measure of the distance of the object to be lo
the coupling condenser 28 the anode 25 has a cor
responding change in voltage. The pulsing of
cated. The length and time scale of the trace
H are respectively determined by the amplitude 50 the grid .2! accordingly drives the anodes l6 and
and slope of the sawtooth wave.
25 negative for the duration of the pulses 3a.
The negative driving of the anode 25 stops con
In order that the deflections 8 and '9 may be
kept separated so that the distance may be more
duction through the diode 23. At the end of the
easily measured, it is desirable that the slope of
pulses 3a- the condenser I5 charges through the
the sawtooth wave be adjustable as indicated at 65 charging resistance l9 and also through the con
The horizontal plates in of the cathode ray
tube are connected to a sawtooth sweep circuit,
denser 28 and the resistance 26 in series with the
potentiometer 27. By moving the tap on the po
modi?cations may be made without departing
from the spirit thereof, and I contemplate by the
tentiometer up or down from the position illus
appended claims to cover any such modi?cations
as fall within the true spirit and scope of my
What I claim as new and desire to secure by
trated, the rate of charge through the resistance
will be increased or decreased so as to vary the
rate of recovery of the potential of the anodes
Letters Patent of the United States is:
l8 and
When the condenser I5 is charged
i. A saw~tooth sweep circuit comprising, a con
to the voltage at which the diode 23 becomes con
denser to be charged to a saw-tooth voltage, a
ducting, further increase in the condenser volt~
pair of charging resistances, one of the resist
age is prevented. Depending upon the setting
ances ‘being connected to the high side of the con
of the potentiometer 27, the rate of recovery of
denser and the other of the resistances being
the voltage of the condenser [5 may be varied as
connected to the low side of the condenser
indicated at E2, I3, and H4 in Fig. 2. The most
through a rectifier and to the high side of said
gradual slope ill will provide a time scale for the
trace permitting measurement of the interval 15 ?rst condenser through a second condenser, said
recti?er being poled to conduct at a predeter
between the de?ections B and 9 up to the maxi
mined charge, and to prevent further charging,
mum range of the equipment. steeper slopes,
of the ?rst condenser, and keying means for
such as l2 and I3, will be used for shorter ranges.
periodically discharging said first condenser.
The sawtooth wave appearing at the anode 25
2. In equipment having a cathode ray tube
is fed to the horizontalvplates of the cathode ray
utilizing a saw-tooth voltage for providing a time
tube '3 through a double triode ampli?er tube 351
scale trace, a sweep circuit comprising a con
having anodes 3i and 32 connected to the power
denser to be charged to a saw-tooth voltage, a
supplythrough resistances 33 and 34 and hav
charging resistance for the condenser, said resist
ing cathodes 35 and 36 connected to cathode re
sistances 3'! and 38. The grid 39 is connected 25 ance being variable to vary the slope of the saw
tooth voltage, means for applying the condenser
through a coupling condenser 60 to the anode 25.
voltage to the cathode ray tube, means for pe
The grid Al is connected to a tap on a voltage
riodically discharging the condenser, and means
divider 42 connected between the anode 3| and
for limiting the amplitude of the condenser volt
ground. As the grid 39 is driven negative from
age to a value less than that which would be ob
its maximum voltage, less current flows to the
tained prior to normal operation of said dis
anode-3i and the voltage of the anode 3i rises,
charging means ior someadjustments of said
driving the grid at positive and causing a drop
resistance whereby the time scale trace has an
in‘the voltage-of the anode 32. The difference
amplitude independent of the slope of saw-tooth
between the voltages of the anodes 3| and 32 is
applied to the horizontal plates Ill of the cathode 35 voltage and. a repetition rate determined by said
discharging means.
ray tube producing the trace ll.
While I have shown a particular embodiment
of my invention, it will be understood that many
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