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Jan. 14, 1947.
n. E. KENYON
2,414,107
ELECTRONIC TIMING APPARATUS
Filed June §50, 1944
3 ShèetS-Sheet 1
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D. È. KENYGN
ÉÁÄ‘É’ÄÜ?
ELECTRONIC TIMING APPARATUS
Filed June 50, 1.944
S'Sì'zeeüsßsheet 2
Jan. 14, 1947.
2,414,107
n. E. KENYoN
ELECTRONIC TIMAING APPARATUS
3 sheets-sheet 5
Filed June a0, 1944
TIME» TIME-5
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INVENTOR
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DAViD E. KENYON
BY
ATTORNE
Patented Jan. 14, .1947
^
'2,414,107
UNITED sTATEs PATENT AOFFICE
ELECTRONIC TIMING APPARATUS
David E. Kenyon, Smithtown, N. Y., assíg'nor to
Sperry Gyroscope Company, Inc., a corporation
of New York
Application June 30, 1944, Serial No. 543,034
16 Claims. (Cl. 161--15)
2
The present invention relates to counting and
timing devices, and concerns particularly elec
caused by spurious current leakage into or out
of the charge-collecting capacitor.
tronic means Ifor the precise measurement and
continuous indication of recurrent time inter
vals.
’
The employment of electron tubes to control
the charging or discharging of a capacitor and
the subsequent measurement of the change in
Still another object of the present invention
lies in the provision of novel time sweep generat
Ui
ing means synchronized by those pulses of stable
frequency which are employed to measure a pe
riodic interval in terms of the number generated
during the same, the sweep generating means per
potential across the capacitor as a function of
mitting interpolation between the individual
the elapsed time of current flow is a common 10 pulses whose sum defines the interval and there
method of determining a time interval. Although
by affording an interval measurement of in
very short intervals may be measured in this
creased accuracy.
f
manner, the accuracy of a direct reading instru
Other objects and advantages of the inven
ment in terms of the useable fraction of full scale
tion will become more apparent in connection
indication is limited to perhaps one percent by
with the following detailed description of the
the galvanometer employed in the vacuum tube
illustrated embodiment thereof, together with
voltmeter which measures the potential left on
the accompanying drawings, wherein:
the capacitor.
Fig. 1 is a block diagram of a recurrent inter
The prior art also teaches the measurement of
val measuring system embodying the present
time by counting pulses derived from a standard 20 invention;
frequency source, such as the domestic alternat
Fig. 2 is a block diagram of a circuit which may
ing current supply, and the utilization of trigger
be substituted for that portion of Fig. 1 indi
circuits which “scale down” or divide the rate of
cated by dash lines 45 to adapt the structure of
occurrence of the impressed pulses to make pos
the latter iìgure to the measurement of low fre
sible their summation by relatively slow acting
quencies;
electromechanical counters. Devices operating
Fig. 3 is a schematic diagram of a typical step
on this principle are well adapted to measure
counter employed in the structure of Fig. 1;
accurately long time intervals, but they are not
Figs. Liii-4E are graphs of wave shapes illus
suited for indicating the length of recurrent short
trating the operation of the step counter shown
periods with precision.
30 in Fig. 3;
It is, therefore, an object of the present inven
Fig. 5 is a schematic diagram of an electronic
tion to provide means for measuring a recur
switch and indicating circuit employed in the
rent time interval by counting the number of
structure of Fig. 1;
pulses of a precisely known frequency contained
Figs. 6A-6D are graphs of wave shapes illus
within the unknown interval, the total count be
trating the operation of the electronic switch and
ing proportioned among a plurality of indicating
indicating
Fig. 7 is circuit
a schematic
showndiagram
in Fig. of
5; aand
time sweep "
meters for the purpose of providing a reading
many times more accurate than the accuracies
generator employed in the structure of Fig. 1
of the individual meters.
to provide a fine scale indication.
Another object is to provide an electronic inter 40
Similar reference characters are employed in
val meter having charge collecting capacitors `
all the above ñgures to designate corresponding
which are placed at a reference potential by a
parts and arrows are provided to indicate the
pulse generated in response to the commence
direction of energy i‘low.
ment of the recurrent time interval that is to be
In its essential function, the electronic appara
measured and indicating means which are re
sponsive to the potentials on the capacitors only
after the conclusion of this interval for indicat
ing the average length thereof.
A further object is to provide recurrent inter
val measuring means adapted to iurnish a con
45 tus hereinafter disclosed measures a recurrent
time interval. This interval may be that between
any two periodic events having substantially the
same repetition rate no matter what their origin
if they are capable of initiating electrical im
Thus, if the events are the occurrences
of corresponding portions of different waves hav
ing the same predetermined frequency, then the
present apparatus may, if desired, indicate the
length of the recurrent interval between such
50 pulses.
tinuous indication proportional to the potential
appearing across a charge collecting capacitor at
the termination of the charging interval and sam
pled for such a short period thereafter as to
provide a reading substantially free from errors 55 wave portions in terms of relative phase angle.
2,414,107
4
0n the other hand, if the present device responds
to similar portions of the same wave, then the
indicating scales may be calibrated in terms of
-the frequency of the measured wave. This inter
val between the two periodic events is embodied
in a control wave having a length precisely equal
to the interval to be measured. The control wave
causes impulses of a stable frequency to be ap
gular control wave, while the other series of pulses
acts to terminate this wave. Devices having the
properties of generator I6 are well known and
may be dcrived from the Eccles-Jordan trigger
circuit. The length of the wave provided by gen
erator I6 is, therefore, precisely equal to the pe
riod which it is desired to measure.
A frequency standard Il provides waves of
some precise radio frequency, such as 100 kilo
This counting circuit comprises a series of Ih cycles or 1 megacycle, to an electronic switch I8
normally blocking passage of these waves. In
charge collecting capacitors interconnected by
the particular embodiment of the invention illus
blocking oscillators and adapted to be- charged
plied to an impulse counting circuit.
f
in steps by applied impulses.- Each of the oscil
trated in Fig. 1, the periodicity of the pulses which
lators is arranged to be triggered by a critical '
initiate the control wave bears a definite though
potential placed on the preceding capacitor cor l5 not necessarily harmonic relationship to the fre
quency of the standard I1. The rectangular con
responding to a predetermined number of im
trol wave is supplied from generator I5 to the
pulses for the purpose of discharging this ca
switch I8 to permit passage of the standard fre
pacitor and for concurrently supplying a charging
quency waves for precisely the duration of the
impulse to the succeeding capacitor. This charg
ing and discharging action continues as long as 20 interval to be measured. The intermittent out
put of the electronic switch I8 is fed to a block
the control wave permits the pulses to be applied
ing oscillator I9 of a conventional design. The
to the counter chain. Upon the conclusion of the
blocking oscillator I9 is normally quiescent, but
interval, however, the momentary charge on each
adapted to be synchronized at one-half the fre
capacitor in the series remains substantially un
changed until the beginning of the next interval. 25 quency of standard source I'I by the substantially
sinusoidal triggering -waves, every alternate one
These charges reveal the electrical position of
of which it converts into a sharp pulse or voltage
the counter and the residual potential on each
spike which is passed on to a step counter 2|.
capacitor is a measure of the number of im
The step counter .2I, of a type discussed in de
pulses applied thereto in excess of an integral
multiple, including zero, of the predetermined> 30 tail with reference to Fig. 3, has a capacitor
adapted to be charged in discrete voltage incre
number necessary to cause a discharge of the
ments by each applied impulse- 'I‘he potential
capacitor through its associated blocking oscil
on the charge collecting capacitor increases in
lator. Thus, it is evident that the indication of
steps until it exceeds that corresponding to a pre-Y
a potential corresponding to a single impulse left
on a particular capacitor represents a plurality of 35 determined number of impulses. In the case of
counter 2|, this number is designated as five.
impulses originally applied to the beginning of
the chain numerically equal to that factor by
This critical potential triggers a blocking oscilla
tor which serves to discharge the capacitor and at
the same time supply a voltage pulse to another
The total count 40 step counter 22. Counter 22 is similar to counter
which the pulses have been “scaled down” or
divided in the process of passing down the chain
to the capacitor in question.
may, therefore, be determined with precision from
a. knowledge of the number of impulses stored
on each capacitor and the factor associated there
with. The residual potentials on the capacitors
2|, but acts to divide only by two, and feeds a
series of impulses to a step counter 23. Counter
23 divides the pulses it receives by a factor of
ñve and passes on the diminished number to a
are measured after the conclusion of the interval 45 counter 24, which like device 22, reduces the re- '
ceived impulses by a half. A iìnal counter 25
and indicated on a plurality of meters each indi
performs a division by live. It is evident that
cating a convenient portion, such as a decimal
the series of counters may be extended to increase
place, of the total count.
i
the number of pulses that may be counted either
A resetting impulse at least equal to the above
mentioned critical potential is generated in re 50 for lengthening the maximum period which may
be unambiguously indicated or for providing more
sponse to the commencement of each interval
scales if the precision and frequency of the stand
and applied to all capacitors to discharge theml
ard source I'I warrants them.
simultaneously to a reference potential corre
The counting and dividing action of counters
sponding to a zero reading of the counter in prep- `
aration for a new count. The indicating circuits, 55 2l through 25 continues as long as the electronic
switch I8 through the control of the interval de
however, have a time constant such as to pro
iining control wave produced by-generator I6 per
vide a continuous indication despite the inter
mits pulses to be supplied to the counting chain.
mittent flow of information from the counting
Upon the termination of the unknown interval,
chain.
' Referring now to Fig. 1, there is shown an ap 60 a potential is left upon the charging capacitor
associated with each step counter which ls a
paratus which responds to a ñrst- source II of
measure of the electrical position of that counter
periodic signals and a second source I2 of sig
~at the time of the interval termination.
nals having substantially the same period. The
In the illustrated embodiment of the invention,
apparatus serves to measure the recurrent inter
it is desired to indicate the time interval on scales
val between these signals and indicates the length
thereof with a high degree of precision on a
coarse scale meter I3, a medium scale meter I4
and a line scale meter I5. 'I'he ratios of the full
scale readings of the indicating devices- I3, I4
and I5 are powers of ten; consequently the meas
having maximum readings which are some power
of ten units of time, e. g., microseconds. In order
that the various scales may be decimally related,
it is, of course, possible to adjust each step coun
70 ter so that it divides by a factor of 10 and to
ured interval is indicated to at least three decimal
employ separate indicating circuits responding
places.
to the potential on each capacitor whose charge
increases in 10 steps before discharging through
Sources II and I2 supply their pulses to an
interval wave generator I6, wherein one series
the associated blocking oscillator. However, this
of pulses serves to initiate a substantially rectan 75 is not the most reliable arrangement since a rel
5
`2,414,107'
ativeiy small change in operating conditions may
cause such a counter to miscount, dividing in
stead by a factor of 9 or 11. It is, therefore, pref
erable for reasons of stability, to count to 10 in
two operations as is illustrated. Under these
conditions, a uniform decimal scale may be ob
tained by adding the voltages across the capaci
tors of adjacent two step and live step counters
in suitable proportions, the potential correspond
6
its zero position to its full scale position in a
smooth manner.
If, for example, the interval is zero and in
creases constantly, then meters I3 and I4 lic
steady at zero indication. While meter I5 gradu
ally attains its maximum indication. When the
interval exceeds this ñne scale' maximum, meter
I5 drops suddenlyto zero While meter I4 jumps
to its iirst index. The line scale meter then pro
ing to an impulse on the capacitor of a two step 10 gresses to its maximum again, at which point
counter being adjusted to equal one-half the
potential corresponding to a step on the capaci
tor of the next succeeding five step counter.
Leads 26 and 21 supply potentials correspond
ing to the voltages on the charge collecting ca
the medium scale meter jumps to its second posi
tion as the meter .I5 drops again to zero. When
the medium scale meter I4 attains its maximum
indication, it'falls tc zero, while the coarse scale
It
is evident that the three meters may be read from
an electronic switch 28. Switch 28 is controlled
right to left to obtain a highly precise summa
by a wave provided by a metering wave gener
tion of the pulses of standard frequency which
ator 29, which is synchronized after a short de
are contained within the measured interval.
lay created by delay circuit 3I by the termina 20 At the commencement of each interval all the
tion of the wave issuing from generator I6. The
counters are set to zero by discharging their as
switching wave created by generator 29 permits
sociated capacitors. This is accomplished by the
the sum of the potentials on leads 26 and 21 to
provision of a resetting pulse generator 42 which
be applied to a D. C. amplifier 32 only for a short
is act .ated by the leading edge of the substan
time after the termination of the counting cycle.
tially rectangular control Wave from Ygenerator
Limiting the time during which the voltages on
I6 and is adapted to create a sharp pulse in re
the capacitors are sampled is a precaution against
sponse thereto. This pulse is applied over a lead
stray current leakages in these capacitors which
43 to all counters simultaneously. The action of '
may cause the voltages to drift upward or down
the resetting pulse is discussed in more detail in
ward slightly before the recurrence of another 30 Fig. 3, but it may be noted that since this zero
timing cycle.
.
‘
setting of the counters occurs at the commence
The ampliñer 32 is adapted to have a long time
ment of the measured interval, the deleterious
constant so that the output voltage of the am
effects of stray current leakage through the ca
pliiier suffers substantially no change between
pacitor circuits are minimzed.
successive periods of the same duration. The
Fig. 2 illustrates an alternate input circuit ar
meter I3 is connected to the output of amplifier
rangement 45’ which may be substituted for that
32 and provides a continuous indication of the
portion of Fig. l which is enclosed by dashed lines
recurrent charge condition of the counters 24 and
and designated by the reference numeral 45. The
25. The charge potentials on the capacitors as
structure of Fig. 2 is adapted for the precise
sociated with step counters 22 and 23 are im-> 40 measurement of audio frequencies. A source of
pressed over leads 34 and 35, respectively, on an
low frequency 46 is supplied to a square wave
electronic switch 33 similar to switch 28. A D. C.
shaper 41 which corresponds to the interval wave
amplifier 36 like device 32 ampliñes the selective
generator I6 in Fig. 1. The square wave shaper
ly applied potential and drives the meter I4.
41 forms the wave supplied by source 46 into
It is evident that the coarse reading meter I3
substantially _rectangular pulses having lengths
and the medium scale meter I4 indicate only at
corresponding to one-half the period of the ap
discrete points jumping from one position to the
plied waves. The waves produced by wave shaper
next highest as the counters whose potential they
41 are employed as control waves in a manner
reveal pass from one charge condition to the next
similar to Fig. 1. In lieu of frequency standard
possible higher charge condition. It is desirable 50 I1 and electronic switch I8, a stable shock-ex
that the fine scale meter I5 indicate smoothly
cited oscillator 48 is preferably provided. With
throughout its range interpolating between dis
this circuit, the control waves from device 41 ex
crete points on its scale. Thus, if the fine scale
cite the standard frequency oscillations rather
meter I5 may be read to an accuracy of one per
than merely control their passage.
The advantage arising from the employment of
cent, then the three meters enable the count to
be determined to four decimal places. This inter
the shock-excited 4oscillator 48 is that the lead
polation on fine scale I5 is accomplished through «
ing edge of the control wave determines the phase
the employment of a sawtooth generator 31.
of the generated waves as well as the moment
when these waves are applied to the counting
The saw tooth generator 31 produces a linear
time sweep voltage which is initiated by output 60 chain. If the initial phase is not maintained
constant, the interval between the resetting pulse
pulses supplied over a lead 50 _from step counter
and the first pulse provided by the blocking os
2|. The interval wave generator I6 suspends or
cillator I9 does not remain fixed. Under these
freezes the action of the saw tooth generator 31
conditions meter I5 indicates only at discrete
at the instantaneous conclusion of the measured
points like meters I3 and I4 and the interpolat
interval by application of the control wave over
ing action of sawtooth generator 31 is rendered
a lead 40. A potential corresponding to the posi
ineffectual. For this reason, the use of the elec
tion of the saw tooth wave as stopped in its linear
tronic switch I8 in Fig. 1 is preferably restricted
charging cycle somewhere between the zero ref
_ to those applications Where the periodicity of the
erence potential and full charge condition is ap
pulses initiating the control wave bears a deñnite
70
plied over lead 38 to an electronic switch 39 and
though notl necessarily harmonic relationship to
D. C, amplifier 4I similar to the devices previ
the frequency of the standard source I1.
ously discussed. The meter I5 is actuated by the
When the counter is employed with the input
amplifier 4I so that as the measured interval
circuit 45’ rather than 45 then the meters I3, I4
changes, this meter follows these changes from 75 and I5 may be calibrated directly in `frequency
pacitors of counters 24 and 25, respectively, to
15 meter jumps to its ilrst indicating position.
2,414,107
7
rather than merely indicating the time occupied
negative potential with- respect to ground is pre
by a half cycle of the low frequency wave from
vented by the low impedance oñered by the series
source 46.
combination of the two diodes and the small out- --
The step counter 23 which is typical of counters
2| through 25 is shown in detail in Fig. 3. An in
put impedance of the cathode follower 65 which
dissipates all charge more negative than the ref-put lead 5I is connected through a capacitor 52 to
erence potential on cathode 84. The regenera
a cathode 53 and an anode 54_of two diodes con
tive action of the blocking oscillator continues
tained within a common vacuum envelope 55. A
until the anode current reaches its saturation
cathode 56 associated with the anode 54 is at
value. The voltage induced across transformer
tached toa charge collecting capacitor 51 whose 10 62 then becomes zero. Stray and interwinding
other side is held at ground potential. The ñoat
capacitors discharge quickly because they are
_ ing side of the capacitor 51 is also connected t0
small. The anode current then starts to decrease,
a grid 58 of a triode whose anode 59 is coupled
thus creating a positive voltage in the cathode
through a feed-back transformer 62 to its cathode
circuit, regeneration being now in the opposite
6| to form a blocking oscillator` circuit. An an 15 direction. The potential difference between the
ode 63 associated with the cathode 53 is attached
grid 68 Yand cathode 6I is quickly carried below
to a cathode 64 of a triode 65 which has no plate
the cut-oir point and the regeneration stops. The
load but merely a cathode resistor 66 suitably . negative reference potential on the capacitor 51
chosen to provide a cathode follower action. Tri
holds the oscillator in a quiescent condition until
ode 65 has a grid 61 connected through a grid 20 triggered by the next charge accumulation.
resistor 68 to an adjustable voltage divider 69
A facsimile of the voltage excursion of the grid
placed between a source of negative potential and '
58 is impressed across the cathode load 15. The
ground. The adjustable connection between re
lead 35 therefore supplies the indicating circuits
sistors 68 and 69 permits the bias of tube 65 to be
with a wave corresponding to Fig. 4E. The lead
controlled so that the cathode 64 is maintained at 25 11 attached to the blocking oscillator anode 59
some suitable negative reference potential. The
provides the next succeeding step counter with
lead 43 carrying the resetting pulses is con
pulses as shown at 85 in Fig. 4D, occurring at each
nected through a blocking capacitor 1 I to the grid
discharge ofthe blocking oscillator. The numeri
61. Another cathode folower circuit is provided
cal ratio of pulses 85 to pulses 8| is determined,
to measure the potential across the charge col 30 of course, by the number of pulses which capaci-`
lecting capacitor 51 without drawing current
tor 51 accepts before reaching the critical poten
therefrom.
This latter cathode follower com
prises a triode 12 whose grid 13 is connected to the
ungrounded side of capacitor 51, and whose cath
ode 14 is provided with a load resistor 15.
The
lead 34 supplying the indicating circuits is at
tached to the cathode 14.
.
In the operation of the step counter illustrated
l in Fig. 3, pulses shown in Fig. 4B as‘at 8l, are` ap
tial, in this instance after iive steps. ,
The resetting pulse shown at 86 in Fig. 4C and
aligned with the lead edge> of the control wave
82 produces a momentary positive voltage across
the load resistor 66 which causes a current ñow
-through the two diodes in envelope 55, and
charges .the capacitor 51 to a potential equal or
exceeding the critical value necessary -to dis
plied to the input lead 5I for the duration of the 40 charge the blocking oscillator. The , effect of
time interval deñned by a control wave 82 shown
the resetting pulse 86 is therefore to discharge
in Fig. 4A. The negative portions of the applied
the capacitor 51 no matter what its charge con
pulses are readily passed by the diode combina
dition.
tion of cathode 53 and anode 63 and applied to the
The details of a circuit suitable for the elec
cathode load 66. Since the effective output lm
tronic switch 33 and the amplifier 36 are shown
pedance of a cathode follower corresponds to the
in Fig. 5. Leads 34 and 35 attached tothe cath
combination of the cathode resistor in parallel
ode followers in step counters 22 and 23, respec
with a fictitious resistor approximately equal to
tively, are connected through decoupling re
the reciprocal of the variational transconduct
ance of the tube, the impedance between the
cathode 64 and ground is low. The negative
pulses are therefore substantially snorted to
sistors- 9| and 92, respectively, to the control
grid 93 of a .triode 94. Trlode 94 acts as a cath
ode follower stage and has a cathode load resistor
95 shunted by, a large value capacitor 96. This
ground.` The positive portions of input pulses 9|
load circuit is connected to a grid 91 of a second
are barred from this circuit by the action of the
cathode follower 98 which, in turn, has a load re
diode, but are free to pass from anode 54 to cath
sistor 99. The load 99 is attached to an adjust
ode 56 and charge the capacitor 51 in steps. 'I'he
able voltage divider IOI. The meter I4 is coninitial bias on the blocking oscillator is equal to
nected together with a resistor |02 in series with
' the negative potential of cathode 64 and is such
the voltage divider I0| and a second voltage di
as to keep the blocking oscillator quiescent. The
vider I03 interposed between a negative potential
potential on the capacitor 51 increases according 60 source and ground.
to the wave 83 shown in Fig. 4E. Upon applica
y 'I'he grid 93 of triode 94 is also connected to the
tion of every ñfth pulse, however, the voltage
anode |04 of a rectifier |05 formed by connecting
across capacitor 51 reaches a critical or triggering
the grid of a triode to its plate. The cathode |06
potential such’as indicated by reference numeral
of the rectiñer |05 is attached to the anode |01
84.
of a triode amplifier |08 having a» plate load re
At this voltagel amplitude plate current com
sistor I 09. The gri-d III of triode |08 has a grid
mences to flow through the transformer 452. This
resistor II2 which is coupled through a blocking
action induces a negative voltage between the
capacitor II3 to the lead 30 upon which is im
cathode 6I and ground, which causes a further
pressed the metering wave lfrom generator 29.
rise in plate current flow. This action is regen 70
In the operation o_f the circuit shown in Fig. 5,
erative and the grid 58 swings highly positive with
respect to the cathode 6I and permits current ñow
which discharges the capacitor 51 to the negative
reference potential. Any attempt on the part of
the discharge to place capacitor 51 at a more 75
the step voltages from the two step counter 22
and the iive step counter 23 are mixed by the par
allel feed of leads 34 and 35 through the resistors
9| and 92 which can be adjusted to provide a
uniform ten-step Wave form. Figs. 6B and 6C
9
2,414,107
illustrate the wave shapes ||5 and |20, respec
tively, impressed on leads 34 and 95, respectively,
and Fig. 6D shows with dashed lines ||6 the
summation of these voltages in such proportion
as to provide a. uniform scale. The wave shape
||6 does not, however, appear on the grid 93 be
cause during the timing interval tube |08 is con
ducting, causing a voltage drop across .the load
resistor |09 such as to keep the anode |01 at sub
,
10
counter 2| is connected through a coupling ca
.pacitor |33 to the pentode grid |3 | , The potential
on the charge collecting capacitor |2| is meas
ured without drawing current therefrom by
means of a cathode follower stage |34 which has
a cathode load |35 to whose high potential side
the lead 38, supplying the switching, amplifying
and indicating circuits 39, 4| and I5, respectively,
is attached.
stantially the negative reference potential al 10 In the operation of the circuit shown in Fig. '1,
though, of course, at a positive potential with
the interval wave generator I6 supplies the con
respect to its cathode. Under these conditions,
trol wave with a positive polarity over lead 40.
any potential applied by leads 34 or 35 to .the
This wave flows through the series resistors |21,
grid 94 more positive than this negative reference
| 26 and |25 and causes the potential on the
potential is conducted through the rectifier |05 15 anode |24 of the diode |23 to be displaced in
to ground.
'
After the conclusion of the interval 82 shown
in Fig. 4A, the metering wave illustrated in Fig.
6A at ||1 is applied with a negative polarity to
to the grid ||| of the tube |08 thereby cutting
ofï current flow -through resistor |09 and render
ing the rectifier |05 inoperative. The tube 94 is
thus permitted to respond to the voltages supplied
over leads 34 and 35. These voltages correspond
to the residual charges on the capacitors in the ~
step counters as mixed by resistors 9| and 92. The
capacitor 96 assumes a voltage in accordan-ce with
a positive direction. This allows diode |23 to con
duct, drawing current through the high resistance
of resistor |26 and gradually charging capacitor
|2|. The increase in potential across capacitor
| 2| is substantially linear with respect to time.
This charging action continues for the dura
tion of the measured interval. Meanwhile, how
ever, pulses from the counter 2| are periodically
impressed upon control grid |3| of pentode |29.
Tube | 29 is thereby made momentarily conductive
and effectively shorts the capacitor |2| to ground.
The potential across capacitor |2| therefore is
this charge as indicated by the solid line ||8 in
very rapidly reduced to zero and immediately
Fig. 6D. The metering wave allows this voltage
starts to recharge through the diode |23. It is
to be applied for a short period at the termina 30 evident that substantially saw-tooth waves are
tion of which the connection between the step
generated across capacitor i 2| as long as the
counters and the cathode follower 94 is removed
measured interval lasts. At the termination of
and all further voltages on the grid 93 are short`
ed by the combined action of -tubes |08 and |05.
As has been mentioned, this momentary sam- ‘
pling of the residual potentials shortly after the
end of the measured interval is designed to render
the indicating circuit substantially independent
of leakage in and around the charge collecting
capacitors. Therefore, the charge on the capaci
tor 96 is readjusted for a short interval having
the same repetition rate as the measured interval.
The time constant of the parallel combination
of resistor 95 and capacitor 96 is very long and
the potential on the grid 91 is substantially free
from ñuctuations. The cathode follower 98
drives the meter I4 without loading the capaci
tor 96. The calibration of meter |4 may be ad
justed by the voltage divider |0|, while the zero
setting may be corrected by the voltage divider
|03. The meter |4 may be placed at a point re
mote from the remainder of the apparatus with
out resorting to shielded cables, since the circuit
impedance is relatively low.
the interval. however, the control wave from gen
erator I6 stops charging the capacitor and no
more discharging pulses are supplied from the
counter 2|. Under these conditions, the capaci
tor |2| is neither allowed to accumulate charge
nor is it discharged, and therefore retains what
ever intermediate charge it has acquired at the
instant the interval ends. Although the cathode
follower |34 impresses a replica of the potential
across capacitor |2| over lead 38, it is only this
last charge condition which the electronic switch
39 permits the fine scale meter |5 to indicate.
The present invention has been disclosed as
embodied in an apparatus which is not limited in
its speed of response by the inertia of mechanical
elements, which is well adapted to provide remote
indication, which affords highly accurate meas
urements while utilizing circuits comprising corn
ponents having liberal electrical tolerances, and
whose principle of operation finds application in
such apparently different fields as 10W frequency
measurement and high speed photoelectric count
A suitable circuit for the time sweep generator , ing or sorting.
31, is shown in detail in Fig. 7. A charge collect
Since many changes could be made in the above
ing capacitor |2| is connected between the cath
construction and many apparently widely differ
ode |22 of a diode |23 and ground. The diode |23
ent embodiments of this invention could be made
has an anode |24 which is attached to the junc
without departing from the scope thereof, it is
tion of resistors |25 and |26. Another resistor
intended that all matter contained in the above
|21 is joined to the end of resistor |26 opposite 60 description or shown in the accompanying draw
ings shall be interpreted as illustrative and not in
resistor |25, the three resistors |21,` |26 and |25
a limiting sense.
forming a series circuit placed between positive
What is claimed is:
and negative sources of potential. The point of
1. Apparatus for measuring a time interval by
attachment of anode | 24 is arranged to be at sub
stantially zero potential. The control lead 40 “ counting the numberof waves of known fre
quency contained within said interval comprising
from generator |6 has a connection incommon
a source of waves of said known frequency, a step
with resistors |26 and |21.
counter having a capacitor adapted to be charged
The ungrounded side of the capacitor |2| is
in discrete voltage increments by each cycle of
also attached to an anode |28 of a pentode |29.
said waves, means for placing a reference poten
The pentode |29 is maintained in a nonconduc
tial on said capacitor at the commencement of
tive condition by a negative bias placed on its
said interval, means for applying said waves to
control grid |3| .and supplied from a negative
said counter during said interval, and means
source through a grid resistor |32 attached
responsive to the difference between the poten
thereto. The lead 50 coming from the step
tial present on said capacitor upon the conclusion
9,414,107
1l
of said interval and said reference potential to
indicate Ithe number yof cycles applied to said
counter.
-
2. In apparatus for counting a recurrent series
of impulses, a capacitor, means for charging said
capacitor in steps to successively higher potentials
ing impulse to the succeeding capacitor, meter
ing means responsive only between said groups
of impulses for measuring the residual potentials
on said capacitors to determine the number of
impulses applied thereto in excess of integral
multiples of said predetermined number> of im
pulses, means generating a resetting impulse at
sive to a critical potential for discharging said
least equal to said critical potentials, and means
capacitor after a predetermined number of im
for applying said resetting impulse at the com
pulses, means responsive only between said recur-> 10 mencement of the' next group of impulses to dis
rent series of impulses for measuring the residual
charge all said capacitors simultaneously.
potential on said capacitor to determine the num
7. Apparatus for measuring a time interval by
ber of impulses in excess of an integral multiple
counting the number of waves of known ireof said predetermined number of impulses, and
quency occurring during said interval compris
means generating a resetting impulse at least
ing means for generating waves of said known
equal to said critical potential for discharging said
frequency, means for forming a substantially rec
capacitor at the commencement of the next series
tangular wave having a duration equal to said
of said impulses.
interval, a capacitor, means responsive to the
3. In apparatus for counting a recurrent series
leading edge of said rectangular wave for plac
of impulses, a capacitor, means for charging said 20 ing said capacitor at a reference potential, means
capacitor in steps to successively greater poten
controlled fromsaid wave forming means for
tials in response to successive impulses, a block
applying said waves of known frequency to said
ing oscillator arranged to discharge said capaci
capacitor only during said interval, means for
tor when the potential exceeds that correspond
altering the potential on said capacitor from said
ing to a predetermined number of impulses, me
reference potential in steps in response to said
tering means responsive only between said recur
applied Waves,- and means responsive to the dif
rent series of impulses for measuring the residual
ference between the potential _present on said
potential on said capacitor to determine the num
capacitor upon the conclusion of said interval
ber of impulses in excess of an integral multiple
and said reference potential to indicate the num- of said predetermined number, and means pro 30 ber of cycles applied to said counter. `
ducing a resetting impulse for discharging said ca_
8. In apparatus for measuring a time interval
pacitor at the commencement of the next series
by counting the number of timing waves of known
of said impulses.
frequency generated during said interval, means
4. In apparatus for counting a recurrent series
for interpolating between adjacent, periods of
of impulses, a capacitor, means for altering the
said timing waves comprising means for forming
potential on said capacitor from a reference po
a. control wave characterizing said interval, a
tential in steps in response to said impulses, a .
charge collecting capacitor, means responsive to
blocking oscillator arranged to return said ca
said control wave for gradually charging said
pacitor to said reference potential when the po
capacitor
throughout said interval, capacitor dis
tential reaches a magnitude corresponding to a
,predetermined number of impulses, metering 40 charging means, means responsive to said con
trol wave for applying said timing waves to said
means responsive only between said series of im
discharging
means during said interval to dis
pulses for measuring the residual potential on
charge said capacitor periodically and abruptly,
said capacitor to determine the number of im
and means for measuring the charge potential on
pulses impressed thereon in excess of an integral
said capacitor after the conclusion of said inter
multiple of said predetermined number, and
in response to successive impulses, means respon
means producing a resetting impulse for return
ing said capacitor to said reference potential Vat
the commencement of the next series of said im
‘val to determine the duration of the same in
excess of an integral number of said timing
periods.
9. In apparatus for measuring a time interval
` 5. In impulse counting apparatus wherein a 50 by counting the 'number of timing waves of known
frequency generated during said interval, means
series of capacitors are charged one from another
for determining the duration of said interval in
in progression, each receiving an impulse upon
excess of an integral number of periods of said
the discharge of the preceding capacitor until
timing waves comprising means for forming a
a predetermined number of charging impulses
have been received and then discharging to pro.- 55 substantially rectangular control wave having a,
duration equal to said interval, a charge collect
vide the succeeding capacitor with a charging»
ing capacitor, means responsive to said control
impulse, the combination of cathode follower cir
wave for continuously and gradually charging
cuits each comprising a grid controlled electron
said capacitor only during said interval, capaci
tube having a cathode load, rectifying means
connected between said'capacitors and said cath 60 tor discharging means, means responsive to said
control wave for applying said timing waves to
ode loads, said rectifying-meansand said cath
said discharging means only during said inter
ode loads providing low impedance paths shunt
val to discharge said capacitor periodically and
ing said capacitors for impulses of undesired
abruptly, means for measuring the charge poten
polarity, and means for applying a resetting im
tial on'said capacitor, and means providing a
pulse to the grids of said cathode followers to
Acontinuous indication of said charge potential
discharge all said capacitors simultaneously.
present at the conclusion of said interval as a
6. Apparatus for counting recurrent groups of
function of said excess duration.
impulses comprising a series of charge collecting
l0. In apparatus for measuring a time inter
capacitors adapted to be charged in steps by
applied impulses, blocking oscillators intercon 70 val by counting the number of waves of known.
frequency generated during said interval, means
necting said capacitors, each of said oscillators
for forming a control wave characterizing said
being triggered by a critical potential on the pre
interval, an oscillator for generating waves of a
ceding capacitor corresponding to a predeter
known frequency in response to said control wave,
mined number of impulses for discharging said
capacitor and for concurrently supplying a charg 75 a step counter supplied Waves from said oscil
pulses.
13
2,414,107
lator, said step counter having a capacitor adapt
ed to be charged in steps by each cycle of said
waves, means responsive to the front edge of said
control wave for placing a referenœ charge on
said capacitor, means responsive to the rear edge
of said control wave for momentarily sampling
the charge on said capacitor, and means for
indicating the momentarily sampled charge con
dition.
14
means responsive to a critical potential for dis
charging said capacitor after a predetermined
number of impulses, means responsive only be
tween said recurrent series of impulses for meas
uring the residuaI potential on said capacitor to
determine the number of impulses in excess of an
integral multiple of said predetermined number
ofimpulses, and means generating a resetting
-impulse at least equal to said critical potential
11. Apparatus for counting recurrent groups 10 for discharging said capacitor.
of impulses comprising a series of charge col
14. In apparatus for counting a recurrent se
lecting capacitors adapted to be charged in steps
ries of impulses, a capacitor, means for altering
by applied-impulses, blocking oscillators inter
the potential on said capacitor from a reference
connecting said capacitors, -each of said oscil
potentialin steps in response to said impulses,
lators being triggered -by a critical potential on1 15 means for returning said capacitor to'said rei'
the preceding capacitor corresponding to a pre
erence potential when the potential reaches a
determined number of impulses for discharging
magnitude corresponding to a predetermined
said capacitor and for concurrently supplying a
number of impulses, metering means responsive
charging impulse to the succeeding capacitor,
only between said series of impulses for meas
metering means responsive only between said 20 uring the residual potential on said capacitor
groups of impulses for adding in ñxed propor
to determine the number of impulses impressed
tions the residual potentials on said capacitors
thereon in excess of an integral multiple of said
to determine the number of impulses applied to
predetermined number, and means producing a
said series in excess of an integral multiple of
resetting
impulse for returning said capacit-or to
the product of the predetermined number of im 25 said reference potential in preparation for the
pulses necessary to discharge each capacitor of
next series of said impulses.
said series, means generating a resetting impulse
15. In impulse counting apparatus, a capaci
at least equal to said critical potential, and means
tor,
means for altering the charge on said ca
for applying said resetting impulse at the com
pacitor in steps in response to applied impulses,
mencement of the next group of impulses to dis 30 means for returning said capacitor to its original
charge all said capacitors simultaneously.
charge condition when the charge potential
12. Apparatus for counting a group oi.' im
. pulses comprising a series oi' charge collecting
capacitors adapted to be charged in potential
steps by applied impulses, blocking oscillators
interconnecting said capacitors, each of said os
cillators being triggered by a critical potential
on the preceding capacitor corresponding to a
predetermined number of impulses for discharg
ing said capacitor and >for concurrently supply
ing a charging impulse to the succeeding capac
itor, and measuring means responsive only after
the application of said groups of impulses for
adding in fixed proportions the residual poten
tials on said capacitors to determine _the number
of impulses applied to said series in excess of
an integral multiple of the product ot the pre
reaches a magnitude corresponding to a prede
termined number of applied impulses, a cathode
„follower circuit comprising a grid controlled elec
35 tron tube -having a cathode load, rectifying
means connected between said capacitor and said
load, said rectifying means and said cathode load
providing a low impedance path shunting said
capacitor for impulses of undesired polarity, and
means for applying a resetting impulse to the
grid of said cathode follower to return said ca
pacitor to its original charge condition irrespec
tive of the number of applied impulses. '
16. In apparatus for timing an interval the
combination comprising a charge collecting ca
pacitor, means for continuously and gradually
charging said capacitor during said interval,
means for periodically and abruptly discharging
charge each capacitor of said series.
said capacitor during said interval, and means
13. In apparatus for counting a recurrent se 50 forl
measuring the charge potential present on
ries of impulseava capacitor, means for charg
_ said capacitor at the conclusion of said interval.
determined number of impulses necesary to dis- '
ing said capacitor in steps to successively higherA
potentials in response to successive impulses,
DAVID E. KENYYON.
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