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Sept. 24, 19-46.
2,408,313
L. R- HU‘NTER ET AL
PHOTOELECTRI C COUNTER
Filed Sept. 5, 1942
2 Sheets-Sheet l
“824/5
' %IIR ATTO I
sePt- 24, 1946-
1.. R. HUNTER ET AL
2,408,313
PHOTOELECTRIC COUNTER
Filed Sept. 5, 1942
BMWmk wk
I
-4UM_ h_
2 Sheets-Sheet 2
Patented Sept. 24-, 1946
2,468,313
UNITED STATES PATENT OFFICE
2,408,313
PHOTOELECTRIC COUNTER
Lyle R. Hunter, Clairton, and Oliver C. Levander,
McKeesport, Pa.
Application September 5, 1942, Serial No. 457,480
5 Claims.
1
In the preparation of bundles of metal sheets
and the like for shipment, it becomes necessary
4 to know the number of sheets that are in each
(01. 250-415)
2
Figure 3 represents a wiring diagram showing
the circuits for the control of the mechanism.
From the drawings it will be seen that the
bundle. As the sheets move along the line of
travel from the shears which cut the strip into
the desired length of sheets, at a high rate of
toelectric control, the cabinet being shown as
mounted on a table I which comprises convey
speed, counting mechanism must be utilized in
ing instrumentalities for conveying the sheets to
reference numeral 5 indicates a cabinet for a pho
order to give an indication of the number of
a piler 9. The photocell is activated by light from
sheets which pass along the line of travel.
suitable light sources, such as that indicated at
In view of the high rate of travel of the sheets, 10 l l. A plurality of motors [3 drive a conveyor for
it is found that all of the mechanical counting
moving the sheets to the piler, and also for ac
devices which are available up to this time are
tuating an auxiliary conveyor l5 which receives
inadequate to install for the desired purpose of
discarded sorted sheets from the stock which is
this invention, since the speed of actuation of all
being handled by the equipment.
such devices is not rapid enough to keep pace 15
The photoelectric counter, designated at IT, is
with the travel of the sheets, and it has been
located conveniently at an operator’s station l9,
found in practice that every type of mechanical
and it is controlled in the following manner, ref
counter that is available has been tried but has
erence being had to the diagram of Figure 3.
been found to be a failure for the intended pur
From this view, a photoelectric cell is indicated
pose.
20 at 2 I, the cell 2| being in circuit with a rectifying
In view of the many failures resulting from
tube 23 which is positioned in the cabinet 5, and
the installation of the mechanical counting de
which receives current from a transformer 25, as
vices, it has been necessary to resort to other
is shown on the drawings.
means for counting the rapidly moving sheets.
The tube 23 is a standard radio rectifying tube,
In view of this necessity, there has been evolved 25 known in the trade as “Type 80,” which receives
an electrical control system for actuating a
alternating current from the transformer 25,
counting mechanism, the sensitiveness of the
which current results when the transformer is
electrical control system being such that an ac
energized from a suitable source of 110 volt, 60
curate counting of the sheets is attained, quite
regardless of the speed at which the sheets travel.
In general terms, the present invention pro
cycle alternating current.
Each of the thyratron tubes employed in the
system is essentially a hot cathode recti?er in
vides a photoelectric cell in circuit with two thy
which a control grid 4! has been placed between
ratrdn rectifying tubes, current from which tubes
the anode plate 43 and the cathode ?lament 45.
is adapted to actuate a counting mechanism,
In conventional operation of thyratron tubes, the
or other electrical devices operable from the cur 35 cathode is of special construction, being heat in
rent output of the thyratron tubes. This current
sulated and of large emitting area, so that even
is a continuously flowing pulsating direct current.
when operated at low power it is capable of fur
The arrangement of the apparatus is such that
nishing thermionic current of a predetermined
light from a suitable source is directed upon a
speci?ed number of amperes. With the anode
photoelectric cell through the spaces between
at a de?nite potential with respect to the oath
successive sheets moving along an operating line
ode, no ciu~rent will pass until the grid potential
which piles the sheets in suitable stacks or bun
is raised above a certain critical value. When
tiles for shipment to market. It will be under
the grid potential is raised to this value, an are
stood that a ?ash of light which is produced be
suddenly
starts and the full current ?ows, lim
tween the sheets and falls upon the photoelec 45
ited only by the electron emission of the cathode
tric cell must be sufficiently intense to activate
and the resistance in the anode circuit. Once
the photoelectric cell, and consequently, the more
the arc starts, however, the grid loses control and
rapid is the travel of the sheets, the greater must
no longer has any e?ect on the discharge, re
be the space therebetween.
gardless of its potential. The are may be stopped
The invention will be understood more readily
only by removing the anode potential.
from a consideration of the accompanying draw
ings, wherein:
In a thyratron tube, the grid can be used to
start the current while applying an alternating
Figure 1 represents a plan view of sheet han
dling equipment;
voltage to the anode. The are then goes out
Figure 2 represents an elevation thereof; and 55 every half cycle while the anode is negative. It
2,408,313
3
4
will start during the next half cycle only if the
grid potential is above its critical value.
The present invention differs importantly from
the foregoing, in that the discharge in the thy
ratron tubes is controlled by the grid, the dis
charge being stopped when a space between
values all may be modi?ed to suit any particular
installation.
Potentiometer arm 5!? is connected through
?xed protective resistance 58 and conductor 58 to
the cathode ‘60 of the photocell 2!. The anode
62 is connected through conductor 653 to the
grids ill and ill’ of the thyratron tubes 3? and
sheets passes a suitable light source for energiz
39, conductor 64- being connected to the grid til
through resistance 55 and conductor 58, and to
current negative voltage to be applied to the 10 the grid ti’ through resistance $5’ and conduc
tor 68’. The resistances 55 and 06’ are employed
grid during the instant that the photocell 2| is
‘for protective purposes and, in the illustrated
energized, this voltage being greater than the
embodiment of the invention, have a value of 4
alternating current potential between the anode
ing the photoelectric cell, this latter, upon ener
gizing, closing a circuit which enables a direct
and cathode.
'
The resulting interruption of the action of the 15
thyr-atron tube causes an actuation of the counter
solenoid in a suitable direction to transmit mo
tion to the counting device.
As soon as each plate obscures the light source,
megohms.
The thyratron tubes Bl and 39 are similar,
, and are provided with cathode ?laments 1B5, 45',
respectively, and anode plates 83, 43’, respec
tively.
These elements are energized from sections of
the photocell H is deenergized and the thyra 20 a secondary coil of a transformer 25', which is
similar to transformer 25, the primary coils 20
tron circuit reestablished, this circuit being closed
and Z!’ of the transformers 25, 25’ being ener
during the time interval required for the sheet
gized from a 60-cycle,‘1l0~volt alternating cur
to travel completely across the light source. This
rent supply.
time is much longer than the time of ?ashes be
Thus the cathode ?laments 45 and 35' are en
tween the plates, and gives an opportunity for any 25
ergized by section 26’, which gives from about 2
lag in the circuit or counting device to have dis
to about 5 volts, as shown in the diagram, and
appeared before the next operation.
section
energizes the plates t3 and £3’ with
In order to obtain full wave recti?cation, and
350 volts each. Leads 69, ‘it? connect the trans
to increase the sensitivity of the circuit, thereby
rapidly actuating the counter mechanism by ap 30 former section 25’ with the cathode ?lament G5,
the ?lament t5’ being connected across through
plying maximum recti?ed current to the counter
leads l2,
while the ends of the transformer
mechanism, two of the thyratron tubes are em
section 32' are connected to the anode plates 43,
ployed, and there is sufficient inductance in. the
t3’, respectively, by conductors 1-6, it, in which
solenoid coil of the counter to maintain the op
eration of the tubes continuous during the rela 35 are interposed respectively the resistances 89, 82.
tively long time intervals that the photoelectric
The lead '50 of the cathode ?lament i5 is con»
cell is masked by passage of a sheet or plate be
nected through conductor 8% to conductor 50 at
tween the light source and photoelectric cell.
the potentiometer resistance 53, this wire 85 serv
As is shown in Figure 3, the secondary of the
ing as the return line for the photocell 2i and also
transformer 25 is connected in sections to the 40 completing the electronic circuit through the
cathode ?lament of the thyratron tubes.
elements of tube
Thus, one section 26 is con
The transformer section 32' is tapped at the
nected to the ?lament Zl through leads 36, 36
middle third as is indicated at 8%. Conductor 38
and 38, the section 32 of the transformer second
connects the tap 86 to a variable resistance 93
ary is connected to plates 25 and 30 of the tube
23 through leads 1Z0 and 132, respectively, and 45 which in turn is connected to a solenoid for actu
ating the counter ill. Conductor 92 connects the
transformer section 28 energizes the source of
light ll.
solenoid to conductor 812-.
It will be apparent from the drawings (Figure
It will be seen from Figure 3 that with the
3) that two thyratron tubes are employed in order
tube 23 being a “Type 80” radio rectifying tube,
to utilize both of the two alternations of the cur
the cathode ?lament 27 receives 5 volts from the
rent source thereby producing full wave recti?
transformer section 2G, and each of the anode
cation and increasing the sensitivity of the.sys
plates 29 and 30 receives 350 volts from the trans
tem and render the system fully responsive to
former section 32, this being tapped at its mid
the high-speed installations to which the system
p-ortion, as is indicated at 44. These speci?ed
conditions may be varied, however, depending 55 is applied. There is su?icient inductance in the
upon the type of rectifying tube that may be em
solenoid coil of the counter to maintain the op
eration of the tubes continuous during the rela
ployed. Also, the position of the tap 44 may be
adjusted, as may be necessary to provide requi
tively long time intervals that the photoelectric
cell is masked by passage of a sheet or plate be
site current conditions in the remainder of the
tween the light source and photoelectric cell. The
control circuit, as will be pointed out herein
thyratron tubes being in parallel, deliver a total
after.
7
The tap M is shown as being connected by a
current to the counter, which current is the sum
of the current outputs of the tubes, thereby pro
conductor 5.5 and resistance 3i to the variable
ducing extremely rapid actuation of the counter.
resistance ‘iii? of a potentiometer S5. The resist
ance 138 also is connected through conductor 5%? 65 In Figure 3 the ?laments £5, :35’ are rendered
incandescent by alternating current from the
to a suitable resistance 33, which in turn is con
transformer coil 26’. The‘ two terminals of the
nected to transformer section 26 through con
transformer 25’ are connected to the two anode
ductor 52, which is connected as shown to the
plates £3, 133' and the cathodes are connected to
lead 36.
The resistances, in the illustrated embodiment 70 each other, as shown, and to wire 84 of the ex
ternal circuit. Therefore it will be seen that the
of the invention, may have a resistance of ‘7590
thyratron tubes pass unampli?ed pulsating recti
ohms in resistance 3!, to a total of 10,000 ohms
?ed current to the counter circuit. The recti?ed
in resistance 48 and 15,000 ohms in resistance 33.
current in the counter circuit exhibits variations
Resistances 3i and 33 are ?xed resistances and
are employed for protective purposes. These 75 which depend on those of the supply voltage but
2,408,313
5
6
there is no interruption. In order to reduce these
tric cell is energized by the ?ash of light passing
between the moving plates.
variations and obtain a more uniform recti?ed
current through the counter solenoid, advantage
The photoelectric cell therefore acts as a very
rapid circuit maker and breaker, which is re
quired because of the high speed of travel of the
is taken of the inductance of the solenoid coil
which‘assists in such action by smoothing out the
pulsations of the recti?ed current, and prevents
sheets; and each time the photocell is energized,
that instant of energization interrupting the
thyratron circuit to make the latter operative
stopping of the tubes as the current never reaches
the zero point.
It is thought to be unnecessary in view of the
foregoing explanation to discuss the circuits in
detail. One of the characteristics of the thyra
tron tubes is that they operate on a difference in
voltage between the independent cathode and
anode circuits of from 3 to 7 volts, which voltage
again to actuate the counter the instant that each
of the successive moving plates interrupts the
light source; so that the thyratron circuit is closed
during the length of time that each sheet passes
over the light source, which is relatively long com
pared to the length of time that the photocell is
15 active.
may be considered negative since the arc in the
tubes passes from the plate to the cathode ?la
Usually the sheets move on the conveyor at a
ment. The voltages of the current supply and
speed of about 800 feet per minute with a space of
the value of the resistances til, 82, t5, 5:8, 58 and
1/4 inch between the sheets. This means, there
86' must be adjusted so as to give this voltage
fore, that each quarter-inch space between the
difference between the independent anode and 20 sheets passes over the light source in l/égguogo of a
cathode circuits.
minute, or 1/5400 second. That means, therefore,
Upon the attainment of this condition, the
that in 1,6400 second the photocell must energize
thyratron tubes operate, and a pulsating direct
and enable the grids of the thyratron tubes to
current passes continuously through the counting
interrupt the thyratron circuit, due to potential
device ll. But it is desired not to have a con~
drop across resistance 68a. Then at the expira
tinuous current flow through the counter, as the
tion of 1/6400 second, the thyratron circuit closes
latter will fail to operate under this condition, but
and actuates the counter to count one unit, the
it is necessary to interrupt this current periodi
thyratron circuit remaining closed and the tubes
cally responsively to the spaces between the sheets
arcing during the time interval that it takes the
in order for the counting device H to reset to
length of the sheet to pass over the light source.
count the sheets accurately.
Then as the plate moves out from the light source,
The interruption of the tubes is effected by
during the next 1/6400 second that the photocell is
impressing on the control grids iii, :3 i ', a negative
energized, the cycle of operation is repeated.
direct current voltage by a value greater than
It will be seen in view of the high speeds in
the positive 3 to 7 volt difference between the
volved that instrumentalities must be employed
anode plates and ?laments.
which operate instantaneously without lag. The
This is accomplished in the following manner.
photoelectric cell is free from lag, as are also the
The anode plates 29 and 38 produce a pulsating
rectifying tube 23 and the thyratron tubes 31 and
direct current from the tube 23, some of this cur
39, and the time interval during which the sheets
rent being conducted through the potentiometer
- pass over the light source and with attendant
35 and conductor 58 to the photocell 2!, the po
tentiometer arm 54 being suitably adjusted to
the solenoid coil of the counter to be taken up
de~energization of the photocell enables lag in
supply sufficient voltage for the photocell and also
and reset ready for the next counting.
supply a voltage to the grids iii, Ill’ of at least 3
It will be seen from the drawings that the con
to '7 negative volts greater than whatever voltage 45 ductor a2 is joined to the conductor 8!} at the
is between the plate and ?lament of each tube,
point 94, at which point there is shown connected
when the photocell is operating responsively to
a conductor 95, which connects with the conduc
light hitting the photocell through the space-s be
tor es at the point 88. The conductor 53 is shown
tween the traveling sheets. Thus, for example,
as being grounded at l?t through condenser Hi2,
if the voltage between the plate and ?lament of
this condenser being an optional provision, in cer
each tube is 150 and the voltage drop across the
tain installations it being found to be needed to
photocell, for example, is 90 volts, the potenti
smooth out the operation of the system. The
ometer must be adjusted to take care of the 90
conductor line 91% $8 with its resistor Hi4 serves
volts and to impress at least from, say 153 volts
to balance the photocell and thyratron tube cir
to 157 volts between the grid and cathode ?lament
cuits. There is also provided a condenser W5,
in each tube. It will be seen, therefore, that under
which is connected across the photoelectric cell
these conditions, the rectifying circuit would be
2!, this condenser rendering smooth the recti?ed
required to supply at least 243 volts through the
current from tube 23, which otherwise would be
potentiometer 35. This voltage is a positive direct
subject to peak variations,
current voltage and must be su?icient to, in effect, 60
The values of the respective units indicated on
change the voltage differential between the plates
the drawings are illustrative only, they being
and cathode ?laments 45, G5’ to negative in order
determined for each change of the load operated
to interrupt the action of the thyratron tubes
by the circuit, it being understood that the in
and obtain a resetting of the counter mechanism
vention is not limited necessarily to the particular
during the in?nitesimally short period of inter 65 embodiment herein speci?cally illustrated and
ruption of the thyratron tubes, the counter mech
described.
anism operating to count upon closing the thyra
We claim:
tron circuit.
1. An electrical control system which comprises,
It will be understood, of course, that the poten
in combination, a source of light, ?rst and second
tial on the thyratron anodes and cathodes is an
rectifying instrumentalities for rectifying alter
alternating current potential, the action of the
tubes being controlled by a direct current poten
tial of suitable value andclirection applied to the
grids of the thyratron tubes; and this direct cur
rent potential is applied only when the photoelec 75
nating current, a load device operated by unam
pli?ed recti?ed current from the second rectify
ing instrumentalities, and means electrically con
necting the ?rst and second rectifying instrumen
tilities including light responsive circuit making
gnome-1c:
and. breaking means; for:- transmitting at; inter-'
vals of in?nitesimal duration unampli?ed; recti.fled‘ current;- from1 the. ?rst. rectifying instrumen
talities to: the“ second rectifying.instrumentalities,.
the. said light-responsive circuit making,‘ and:
breakingmeans' being. adapted?o. be completely’
masked;from: the source: of lightv over relatively‘
long. periods of time, but being exposed‘ to; light}
from. the light source duringin?'nitesimally. short
anode,. a. cathode,~.andv a control grid,, the.- anode:
and cathodeof; each‘tube being. connected to-a.
suitable source’ of alternating current. and. the.
cathodesbeing, connected together, whereby the‘
tubes are. adaptedto deliver an unampli?ed. pul
eating. unidirectional. current, a load device»
adapted to receive the said-.unampli?ed pulsating;
unidirectional current, means includingthesaidv
photoelectriccell for connecting the. grid: of; each
time intervals . between the. relatively. long periods
' of ' the: said thyratron-type tubes with the said.
of masking, the resulting. transmitted’ current.
being of: a potentialand polarity'suitable, to pre.L
determinately'interrupt action. ofathegsecondlrecs
tifying' instrumentalities for actuating the. said.
rectifying1circuit,.the- photoelectric ‘cell beingjren-
dercdirstantaneously responsive‘ to an in?nitesie
mally short: ?ash oflight‘ passing .from the. light.
source to‘ the‘ photoelectric cell, the said photo:
151' eleotric cell beingadapted to closeacircuit. from:
load device.
the. rectifying circuit- through the, grid of each.
2. An electricalcontrol system, which comprises
thyratronetype. tube during the: in?nitesimally'
the-combination .witha.sourceiof-light, of- a photo; 7
shortmoments of conductivity.- of. the. photoelec-v
electric cell. adapted to; be completely‘ maskedi
tric; cell and to. open the circuit during relatively
from. the source of; light; overv relatively‘ long‘
periods of, time, but; being. exposed to lightiro'm: 202 long intervals duringwhichthe cell is:completely;
masked, the said cell during successivemoments;
the-light source: duringin?nitesimally short-time.
of conductivity transmitting. to; the grids of. the
intervals between. the. long. periods‘- of. masking,
thyratronetype. tubes a succession. of. momentary:
the saidxphotoelectric cellbeingthereby rendered:
unampli?ed: unidirectional; currents. control.
conductive; by in?nitesimally short light flashes:
meansior the:said unidirectional current sothat,
resulting from the‘ light. passing." tov the; cell be.
current. of. a. potential and. polarity will be im-»
tween'the masking periods, ?rstandsecond recti
pressed . on .the ; grids suitable 1 to - neutralize. alter.
fying instrumentalities for rectifying. alternating:
nating; current; potentials: between. the: anode. and.
current,.the ?rst rectifying. instrumentalities pro
cathode. of eachof the- thyratron-typa tubes. for
ducing. a‘ pulsating. unampli?ed unidirectional.
current, a; load. operated. by current from the 3 U 1 interrupting actioniof the-tubes, thereby momenr
tarlly actuating the load device toconditionthe;
second; rectifying. instrumentalities;. the said sec‘
a
.
ond. rectifying. instrumentalities . including recti-v
same. for; further actuation‘ through a; succeeding
fying tubemeansincluding an: anode; a cathode,
and a.contr.ol grid, the said anode: and cathode
relatively long period of: masking. of. the photo
electriccell, the load device being:thus;conditioned.
each time: amomentary ?ash of light reaches the;
beingconnected torsuit‘ablet supplies of alternating
current; the: rectifyingitube; meansheing adapted.
to; deliver-an unampli?ed pulsating: direct. current‘
to.the said'load, means connecting the ?rst; recti
fying.instrumentalities.in: circuitwith: the; control f
grid,'.tl1e. connecting means including the: said;
photoelectric. cellwhich. is instantaneously: oper
able. responsively toxin?nitesimally ‘short; exposure:
to light from the; light. source, thephotoelectric:
cell being adaptedxto: clcseithe: circuit: through the
D.
photoelectric cell from thelightsource;
can. electrical. control; system, which com
prises-the combination Withia source-or light,.of
a photoelectric cell‘ adapted to‘ be completely
masked. from: the: source. of light.v over relatively.
long periodsof. time; but being exposed. to. light.
from. the lightsource. during in?nitesimally' short‘,
time intervals ' between thee/long‘ periods. of; mask.
non-conductive duringzthezrelatively long; periods1
ing, the said‘photoelectric cell being'thereby rem.
dered. conductive by;v in?nitesimally short; light:
flashes: resulting: from: the light‘. passing, to. the:
cell between. the? masking periods. a rectifying:
during, which: the cell is. masked-.froini the light;
source, therce'll thereby. transmittingtothe con--~
tiiyin'g; tube. having diode; characteristics at: any’
grid during the,in?nitesimally'short exposuresto
the; light; and‘ to: open. the: circuit. when; rendered:
trol; grid‘ during." successive; in?nitesimally' short‘
circuit . including. av transformer; and a‘. trioide. rec.
of. a. potential and’ polarity suitable" to: neutralize;
. givenrinstantior obtaining full wave recti?cationg.
the. said. circuit; being adapted: to‘ deliver ' an une/
ampli?ed unidirectional . current,. second. rectify
alternating current potentials. between the: anode.
ing instrumentalities- including a' second triode;
periods :ofconductivity'of - thecelli a" direct current;
and cathode‘ of. therectiiying tube means" toine'
terrupt: action of there'ctifyin'g: tube means for
actuating the‘ load device . incident to: restarting
the. rectifying‘ tube . means.
An electrical controlsystem whichcomprises
the combination with a sourceroflight’, ofl'a photoelectric cell‘ adapted to be completely masked
from the source of. light‘ during relatively. long
rectifying circuit. including . a second‘ transformer.
1: and. a. pair: of i triode- thyratron-type. tubes con.
nected to sections‘; of the: said. transformer‘ and.‘
adapted toproduce fulllwave. recti?cation, a load.
device operated by'unamplified': recti?ed current
from thextliyratron-type'tubes,.the said-rectifying
circuit being connected. through the photoelectric:
cell .to: a control gridof each of: the triode. thyra'e
tron-type; tubes. for‘ impressing: momentary= uni
periodsof time while being'exposed to light from
directionalcurrentto the saidgrid: of each of the;
thelight source during in?nitesimally short-time
triode: thyratronetype' tubes for interrupting
intervals bctweenthe. long periods of" masking,
alternating. current discharge.’ between the“ re:
the said photoelectric-cell‘being thereby rend'eredl
maihing? elements. of; the’ tubes: respon'sivelyv tov
conductive by infinitesimally short light. flashes‘
momentary conductivity of : the». photoelectric: cell
resulting from the light passing to the celliduring
during in?nitesimally short intervals of'time, the
infinitesimally short intervals;betweenithemask
photoelectric cell- thereby momentarily closing
ing periods, a rectifying circuit adaptedrto deliver‘
an ,unampli?ed pulsating. unidirectional‘ current 70 the rectifying. circuit through. the- saidi control
grid in the thyratronetype'tubesi for in?nitesii-i
from an alternating current supply; atthyratron»
mall'y. short'iperiodsiof time as.light;?ashes toitlie:
type'rectiiying circuit comprisinga pair. ofzthyra
photoelectric" 0811,; thereby momentarily: rendering.
tron-type‘tubes, the. said: tubes;being adapted to.
thesaidgcell conductive-rand deenergi'zing. the load
utilize both half ‘Waves of: each: alternating: C1113
rent cycle, the: .thyratron-type: tubes. including an; 75. device; responsively to: the in?nitesimally' short‘
2,408,313
10
interruptions to actuation of the thyratron-type
tubes, the said tubes supplying unampli?ed uni
directional current to the load device during rel
atively long periods of time during which the
photoelectric cell is completely masked from the
light source, the thyratron-type tubes being con
nected in the circuit to be self-starting, the load
device being conditioned for further operation
during the in?nitesimally short moments of actu
ation of the photoelectric cell.
5. Mechanism for counting rapidly moving,
closely spaced-apart metal sheet, which comprises
a predetermined cycle by unampli?ed unidirec
tional current from the thyratron-type tubes, a
potentiometer, the said ?rst rectifying circuit
being connected through the potentiometer and
the photoelectric cell to a control grid of each of
the thyratron-type tubes for impressing momen
tary unampli?ed unidirectional current to the
said grid of each of the triode thyratron~type
10 tubes for interrupting alternating current dis
charge between the remaining elements of the
tubes responsively to momentary conductivity of
the photoelectric cell during in?nitesimally short
the combination with a conveyor having the
sheets to be counted traveling thereon, of a source
of light positioned on one side of the conveyor and
adapted to illuminate the sheets and spaces there
between, a photoelectric cell mounted relative to
intervals of time as light flashes between the
sheets being counted to render conductive the
photoelectric cell, thereby energizing the load
during each ?ash responsively to the in?nitesi
the conveyor for receiving in?nitesimally short
mally short interruptions to actuation of the
?ashes of light from the light source, the said
thyratron-type tubes, the said tubes supplying
in?nitesimally short light ?ashes being the light
20 unampli?ed recti?ed current to the counting
passing through successive spaces between the
means during relatively long periods of time dur
rapidly moving sheets, the photoelectric cell being
ing which the photoelectric cell is completely
completely masked from the light source by pas
sage of the sheets, ?rst and second rectifying in
masked during passage of the sheets between the
light source and the photoelectric cell, the said
strumentalities for rectifying alternating current,
load performing a resetting operating during the
periods of actuation of the thyratron-type tubes,
the ?rst and second rectifying instrumentalities
being free from mechanical and electrical inertia
effects, the ?rst rectifying instrumentalities being
and being actuated to perform the said predeter
mined cycle during the in?nitesimally short inter
ruptions of the thyratron-type tubes as the photo
a rectifying circuit including a transformer and
a triode rectifying tube having diode character 0 electric cell becomes conductive responsive to
istics at any given instant for obtaining full wave
light ?ashes between the sheets being counted,
the thyratron-type tubes being connected in the
recti?cation, the said circuit being adapted to
circuit to be self-starting after each interruption
deliver an unampli?ed unidirectional current, the
and, being in parallel, the said thyratron~type
second rectifying instrumentalities including a
second triode rectifying circuit including a second 35 tubes deliver a total current to the load which is
the sum of the current outputs of the tubes,
transformer and a pair of triode thyratron-type
thereby producing extremely rapid actuation of
tubes connected to sections of the said trans
former and adapted to produce full wave recti
?cation, a load adapted to be operated through 40
the counting means.
LYLE R. HUNTER.
OLIVER C. LEVANDER.
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