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Патент USA US2403510

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July 9, 1946.
2,403,510
T. T. EATON
LOW FREQUENCY DEFLECTING CIRCUIT
Filed Aug. so, 1943
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Patented July 9, 1946
2,403,510 _
UNITED s'rA'rÈs PATENT " OFFICE ‘
2,403,510
LOW-FREQUENCY DEFLEC’IING CIRCUIT
Thomas 'T. Eaton, Haddon Heights, N.' J., assigner
to Radio Corporation of America, a corporation
of Delaware
Application August 30. 1943, Serial No. $100,740'
6 Claims.
(Cl. 175-335)
.
2
,
My invention relates to electromagnetic de
iiecting circuits and particularly to circuits for
a motor driven cam i t.
deflecting a cathode ray or the like at a very low
` 'I'he saw tooth voltage it is applied through>A a
I3 is closed periodically for `a short interval by I
,
repetition rate.
direct-current connection to the control grid ‘Il
In apparatus where it is desired to deiiect a
cathode ray at a very slow rate, such as a rate
of one deñection pe:l second, tor example, it is
of a high impedance vacuum tube suchas a pen
common practice to obtain the deiiecting voltage
or current by mechanical means such as a po
tentiometer comprising
current carrying re
sistor and a rotating potentiometer arm that
makes a sliding contact with the resistor. This
method of obtaining a sawtooth wave or the like
for cathode ray deñection has obvious disadvan
tages.
An o'fnect of the present invention is to pro
vide an improved method oi.' and means for pro
ducing a 10W frequency deflecting current for
electromagnetic deilection.
A further object of the invention is .to provide
'tode I8. The cathode It of the pentode may be
connected to ground through a >cathode resistor
2i. which introduces' some degeneration .for
straightening the sawtooth curi-_ent wave.- ".l‘he
value oi' the 4biasing voltage supplied by the bat
tery il preferably is about equal to the cut-ofi
voltage oi’ the tube i8, the capacitor-Il discharg
‘ ing substantially to this voltage while the switch
e I3 is closed.
A suitable anode voltage is applied to the anode
15 20 of tube I 0 through a variable anode resistor
22. One terminal oi' a pair o! detlecting coils `22
is direct«current connected through a conductor
25 to the anode 20. The other terminal o! the
coils 20 is direct-current connected to the junc
an improved method of and means for producing 20 tion point 2l of a resistor 28 and a glow tubev 21
that are serially connected across the anode volt
a low frequency deilecting current of sawtooth
age supply. _The point 2l` is held at a constant
or triangular wave shape.
In one preferred embodiment of the invention.
a sawtooth voltage wave is generated which recurs
potential by the glowv tube 21. For the purpose
oi' illustration it is assumed that the anodey voltage
at the desired repetition rate and4 _this _voltage 25 is 300 y,volts andthatthe constant _potential `at
wave is applied to 'the control grid oi' a vacuum
tube, such as a pentode, having high impedance
The circuits may be adjusted for operation by
applying to the control grid i1 the average volt
between anode and ground. The anode circuit
age Vi oi' the sawtooth wave Iii and by ad
oi' the tube includes an anode resistor and a pair
Justing vthe resistor 22 -until the voltage drop
oi' deiiecting coils which have one terminal di
thereacross equals the constant potential at the
rect-current connected to the anode. 'I'he other
Junction pointu, or, in the- example assumed,
terminal of the deñecting coils is direct-current
_until the voltage drop'across resistor 22 is 150
connected to a point that is at a steady poten
volts. -There will now be no current ñow through
tial which is lower than the anode supply po
tential. If, with a ñxed voltage (such as _the 35 the deilecting coils 2l.
‘ When the voltage wave I0 is applied to the grid '
average sawtooth voltage) on the control grid `oi.'
the tube, the resistance of the anode resistor'
is adjusted until the anode potential equals said
lower potential, the current now through the coils
will then be zero. Any increase or decrease in
the control grid voltage will cause ys. correspond
ing current iiow in the deiiecting coils in one di
rection or the other to produce the desired elec
tromagnetic deflection.
«
il, with the circuit adjustedv as described above,
a sawtooth current will flow through the coils 23;
the .current flowing in one direction when the
sawtooth lvoltage is below the average value, and
in the opposite direction when the sawtooth volt
. nge is above the average value. .
Centering may be accomplished lby .changing
the adjustment ofthe resistor 22. It the resistor '
The invention will be better understood from
the following description taken in connectionl
with the accompanying drawing in which the sin
22 hasia much larger resistance than the re
then discharging the capacitor I I rapidly through
‘a switch I2 and a biasing battery M.' The switch
ing. voltage-values have been'indicated merely
sistance of the denecting coils 2l, (the resistance '
o! the coils 22 being indicated at 22') the size or
amplitude oi' the sawtooth deiiecting current will
gle ligure is a circuit diagram oi' one embodiment
' remain substantially unchanged with changes in
oi' the invention.
the centering adjustment. In order to avoid wave '
Referring to the drawing, a sawtooth voltage
shape distortion, the reactance ’of the deilecting
wave> In is generated by charging a capacitor. il
coils 23 should be small compared'with the re
slowly through a high impedance resistor I2 and
sistance of the snode're‘sistor 22.4 In the draw
by way o! example.
-
‘
2,403,510
3
I claim as my invention:
1. A low frequency deñecting circuit compris
4
such that the anode voltage equals the voltage o!
ing a vacuum tube having an anode. a cathode
said intermediate potential point when the volt
age on the control grid is at some intermediate
and a control grid, a direct-current voltage sup
value of said periodic voltage whereby deilecting
ply having a comparatively high potential point
and a'n intermediate potential point, means for
holding the voltage of said intermediate poten
current of linear wave form flows through said
deilecting coil in one direction when the control
grid voltage is less than said intermediate value
tial point constant regardless of the flow of de
and ñows through said coil in the opposite direc
tion when the grid voltage is greater than said
ilecting current, said high potential point being
connected to said anode through an anode re 10
sistor, a deñecting coil that is connected between
said“ anode and said intermediate potential point
by direct-current- connections only, means for
producing a periodic voltage wave having a repe
tition rate equal to that of the desired low ire
quency deflection, and means for applying said
voltage -wave to said control grid to produce a
periodic flow of anode current, said anode resistor
having a, resistance such that the anode voltage
intermediate value.
`
4. A low frequency de?ecting circuit compris
ing a vacuum tube having an` anode, a cathode
and a control grid and having high cathode-an
ode impedance, a direct-current voltage supply
having a comparatively high potential point and
an intermediate potential point„means for hold
in-g the voltage oi' said intermediate potential
point constant regardless oi the ilow of deiiecting
current, said high potential lpoint being connected
equals the voltage of said intermediate potential 20 to said anode through a variable anoderesistor,
point when the voltage on the control grid is at
some intermediate value of said periodic voltage
a deilectlng coil that is connected between said
anode and said intermediate potential point by
direct-current connections only, means iorpro
ducing a. periodic voltage‘wave having a >repeti
voltage is less than said intermediate value and 25 tion rate equal to that of the desired low frequen
cy deñection, and means for applying said voltage ‘
i‘iows through said coil in the opposite direction
' wave to said control grid through a direct-currentwhen the grid voltage is greater than said inter
connection to produce a periodic ilow of anode
mediate value.
current, said anode resistor having a resistance '
2. A low frequency deilecting circuit compris
ing a vacuum tube having an anode. a cathode 80 such that the anode voltage equals the voltage of
said intermediate potential point when the volt
and a control grid and having high cathode-anode
age on the control grid is at some intermediate
impedance, a direct-current voltage supply hav
value of said periodic voltage whereby deñecting '
ing a comparatively high potential point and an
current flows through said deilecting coil in one
intermediate potential point, means for holding
the voltage of said intermediate potential point 35 direction when the control grid voltage is `less
than said intermediate value and ilows through
constant regardless o! the ilow of deñecting cur
said coil in the opposite direction when the grid
rent, said high potential point being connected
voltage is greater than said intermediate value.
to said anode through a variable anode resistor, a
5. A low frequency deilecting circuit com
deiiecting coll that is connected between said an
ode and said intermediate potential point by di 40 prising@ deiiectlng coil. a vacuum tube having
an anode, a cathode and a control grid and
rect-current connections only, means fory pro
ducing a periodic voltage wave having a repeti
having high cathode-anode impedance com
pared with the impedance of said coil„a direct
tion rate equal to that of the desired low fre
current voltage supply which `has a voltage
quency deflection, and means for applying said
voltage wave to said control grid to' produce a 45 divider connected thereacross. said voltage
divider comprising a resistor and al constant
periodic ilow of anode current, said anode resistor
voltage device connected in series with each other
having a resistance such that the anode voltage
with the constant voltage device at the low po
equals the voltage of said intermediate potential
tential end, said constant voltage device having
point when the voltage on the control grid is at
some intermediate value of said periodic voltage 60 the characteristic that the voltage thereacross is
substantially independent of the current iiow
whereby deiiecting current flows through said
therethrough within the operating range of_ the
deñecting coil in one direction when the control
device, said anode being connected to the posi
grid voltage is less than said intermediate value
tive terminal oi' said voltage supply Athrough an
and ilows through said coil in the opposite direc
anode resistor. -said deñecting coil being con- ’
tion when the grid voltage is greater than said
nected between said anode -and the Junction point
intermediate value.
`
.
3. >A low frequency deilecting circuit compris
o! said constant voltage device and said voltage
ing a vacuum tube having an anode, a cathode
divider resistor by direct-current connections
only, means i'orv producing a periodic voltage
and a control grid and having high cathode-an- .
wave having a repetition rate equal to that of the
ode impedance. a direct-current voltage supply
having a comparatively high potential point and
desired low 'frequency denection. and means i'or
applying said voltage. wave to> said control grid _
an intermediate potential point, means for hold
to produce a periodic iiow oi' anode current. said
ing the voltage of said intermediate potential
point constant regardless of the ilow or deflect
anode resistor having a resistance such that the
ing current, said high potential point being con
anode voltage equals the voltage at said Junction
point when the voltage on thecontrol 4grid is at’
nected to said anode _through an anode resistor,
a dedecting coil that is connected between said
some intermediate value oi' said periodic voltage.'
whereby deiiecting current nows'through said
anode and said intermediate'potential point by
direct-current connections only, means for pro
deiiecting coil in one direction when the control'
ducing a periodic voltage having a linear wave 70 grid voltageis less than saidy intermediate value
form and having a repetition rate equal to that
and iiows throughsaid coil in the opposite direc
tion when the grid voltage is greater than said
of the desired low frequency deflection, and
whereby denecting current flows through said lde
iiecting coil in one direction when the control grid
means for applying said voltage wave to said
intermediate value.
'
control grid to produce a periodic flow oi anode
6. A low frequency de'?ectlng circuit' com-`
curreut, said anode resistor having a resistance 76 prising a deiiecting coil, a vacuumtube having
A 9,403,510'
5v
an anode, a cathode and 'a control grid anld.'
having high
cathode-anode impedance , com
pared with the impedance of said coil, a direct
current voltage supply which has a voltage
divider connected thereacross, said voltage
divider comprising a resistor and a glow tube
connected in series with each other with the glow .
tube at the low potential end, said anode being
connected to the positive terminal of said voltage
supply through a variable anode resistor, said
defiecting coil being connected between said
equal to that -of the-desired low frequency de
flection, and means‘for applying- said voltage
wave to said control grid'through a direct~current
connection to produce a periodic iiow of anode
current, said anode resistor having a resistance
such that the anode voltage equals the voltage
at said junction point when the voltage on the
control grid is at some intermediate value of
said periodic voltage whereby defiecting current
flows through said deñecting coil in one direction
when the control grid voltage- is less than said
intermediate value» and flows throughvsaid coil
in the opposite direction when the grid voltage is
anode and the junction point of said glow tu'be
and said voltage divider resistor by direct-current
greater than said intermediate value.l
'
connections only, means for producing a periodic
'THOMAS T. EATON.
sawtooth voltage wave having a repetition rate 15
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