вход по аккаунту


Патент USA US3056133

код для вставки
Sept. 25, 1962
Filed July 29, 1958
2 Sheets-Sheet 1
| |+x
-M"I I Q
I M I L‘
o Ii"
__ I
Y *28
Sept. 25, 1962
Filed July 29, 1958
2 Sheets-Sheet 2
l l l lw
‘ii/.4, 211M ‘KM
nited Stats
Patented Sept. 25, 1%62
Morris H. Shamos, Riverdale, N.Y., assignor to Tung-Sol
Electric Inc., a corporation of Delaware
Filed July 29, 1958, Ser. No. 751,715
5 Claims. (Cl. 340-237)
This invention relates to alarm devices and has par
ticular reference to an alarm system which will sound
a warning or produce a visual indication when gamma
ray radiation level exceeds a predetermined tolerance
The large increase in the use of radioactive materials
the movable arm of the electrostatic switch, the switch arm
in this embodiment completing an energizing circuit for
the alarm when the switch is actuated.
For a better understanding of the present invention,
together with other and further objects thereof, reference
is made to the following description taken in connection
with the accompanying drawings.
FIG. 1 is a schematic diagram of connections showing
one arrangement of the alarm circuit.
FIG. 2 is a schematic diagram of connections showing
an alternate arrangement using a photoelectric cell and
a self luminous source.
‘FIG. 3 is a graph showing the characteristics of the
during the past few years, coupled with the threat of
radiation hazards resulting from atomic warfare make
two constant current devices.
it desirable to have a simple, automatic radiation alarm
ing another alternate arrangement using two photoelec
which will give a signal when the radiation level exceeds
a predetermined value. Since such devices should be
tric cells.
FIG. 5 is a schematic diagram of connections using
‘FIG. 4 is a schematic diagram of connections show
on duty twenty-four hours a day, it is advisable to use a
an electrostatic switch or relay without a vacuum or
simple dependable arrangement which does not require
gaseous discharge device.
a continuous supply of electrical energy in the standby
The present invention, while primarily directed to the
Referring now to FIG. 1 the alarm comprises an ion
ization chamber 10 connected in series with a constant
current device 11 and a source of potential T2. The
detection of gamma and X-ray radiation, can also be
ionization chamber id is a constant current device within
arranged to act as a smoke alarm and as such can be used 25 a well de?ned range of applied voltages. The constant
in the home or in any building where there is danger
current device 11 includes two electrodes mounted with
from ?re.
lead-in conductors which may be sealed to a partial glass
Radiation alarms used at present generally consist of
envelope. The space between the electrodes, however,
ion chambers or Geiger counters coupled to appropriate
must be open to the atmosphere in order to detect the
‘ampli?er circuits to operate preset relays and alarm sys— 30 presence of smoke. Any other type of insulation mount
In any of these devices hot cathode tubes must
be used which require a continuous supply of heater
ing can be used for the two electrodes as long as they are
securely mounted and open to the atmosphere.
or ?lament current in the standby condition. The level
for which these alarms are set is usually the accepted
space between the electrodes is subject to constant ioniza
tion by some radioactive material such as radium and
35 this material may be conveniently supported on one of
tolerance level, which is 6.25 milliroentgens per hour.
The alarm described herein is an improvement on the
the electrodes as shown in the ?gure. While the circuit
alarm described in Us. Patent No. 2,817,768, issued
will function without any means of ionization in envelope
December 24, 1957 to Morris H. Shamos.
10, it has been found advisable to include some radio
One of the objects of this invention is to provide an
active material in this device also.
improved radiation alarm which avoids one or more of
A discharge circuit is also connected across the source
the disadvantages and limitations of prior art arrange
of potential 12 and includes a three electrode gaseous dis
charge device 13 containing a cathode, an anode, and a
Another object of the invention is to provide a radiation
?ring electrode. The discharge device 13‘ is connected in
alarm which consumes almost no electrical energy in the
series with a high resistor 14, and an alarm 15. A capac
45 itor 16 is connected between the anode and the negative
standby condition.
Another object of the invention is to increase the sensi
terminal of the potential source 12 and aids in the dis—
tivity of radiation alarms.
charge of the device 13 by furnishing a quantity of elec
. Another object of the invention is to provide a radia
tricity which ?ows through the discharge device 13 and the
tion alarm which may be used to detect neutrons or beta
alarm 15 whenever the ?ring electrode renders the device
50 conductive. The ?ring electrode is connected to the neg
radiation as well as gamma radiation.
Another object of the invention is to provide an alarm
ative terminal of source 12 by a high resistor 17.
which detects the presence of smoke.
An electrostatic switch 18 is employed in this circuit to
Brie?y the invention comprises two constant current
make the device more sensitive and more reliable. The
devices connected in series across a source of energy and
switch is enclosed in an air-tight envelope and is a single
an electrostatic switch connected in series with a high 55 pole, single throw switch having a movable element 29,
resistor across one of the devices with its switch arm
which may be a metalized quartz ?ber, and two electrodes
normally positioned between two electrodes, one of
22 and 23, the latter also serving as the switch contact.
which is connected to the junction between the devices
The switch is normally open, as shown in the ?gures, and
and the other of which is maintained at a substantially
under normal conditions of no penetrating radiation, there
?xed potential. Actuation of the switch in response to 60 is practically no force exerted on the movable member to
the electric ?eld existing between the electrodes causes
be actuated. Both electrodes 22 and 23 are at about zero
energization of an alarm device. One of the constant
potential and there is no electrostatic ?eld between them.
current devices may be an ionization chamber having a
When this switch is operated, the movable member 29 is
resistance responsive to penetrating radiation and the
moved to the position indicated by the dotted line and
other of the constant current devices may be sensitive 65 makes contact with a conductor connected to the ?rin
to the presence of smoke and dust. In one embodiment
electrode of the discharge device 13‘.
of the invention the last mentioned electrode of the elec—
Both constant current devices 101 and 11 possess a con
trostatic switch serves as an electrical contact and is con
stant current feature Within their range which extends
nected to the ?ring electrode of a gaseous discharge de
from about 15 volts to about 2001 volts, the upper limit de
vice, the discharge device, when triggered, causing ener~ 70 pending upon the spacing and area of the electrodes. At
gization of the alarm. In another embodiment of the in
values between 0 and 15 volts the devices act as normal
vention a separate contact is provided for engagement by
resistors, and above 200 volts secondary electronic proc
which because of its constant source of ionization can
conduct a larger current. It the voltage of the potential
The circuit shown in FIG. 4 is the same as that shown
in FIG. 2 except that a second photoelectric cell 32 is
substituted for the ionization chamber 10. This second
cell 32 is mounted in a light tight case 33 which may be
made of thin aluminum and which is also gas tight.
A scintillation crystal 34 is mounted within the case
source is 200 volts, then substantially all of this voltage
33 and lights up whenever bombarded by ionizing radi
esses cause the current to increase sharply.
When no am
bient ionizing radiation is being received the ionization
chamber 10 passes only a small current and this current
is below the normal constant current of the device 11,
ation. A small portion of radio-active material 35 such
under these conditions is across the ionization chamber
as a radium salt, is placed adjacent to the crystal to pro
10 and only a few volts, less than the critical 15 volts, is
applied across the constant current device 11.
10 vide the background current necessary to produce the
current indicated by curve A in FIG. 3. The operation
The division of voltages across devices 10 and 11 may
of the circuit is as described above.
be better explained by reference to the graph shown in
For certain installations where a more rugged form of
FIG. 3. Here the characteristic curve of the ionization
electrostatic switch may be used, the gaseous triode 13
chamber 10 is shown at A. The chamber passes a small
may be omitted and the circuit shown in FIG. 5 be em
current I1 because of the small amount of radioactive mate
ployed. This circuit includes two constant current de
rial deposited within its envelope. The characteristic
vices 4G and 41 in series connection, one of the devices
curve B for the constant current device 11 is plotted in a
being controlled by bombarding penetrating radiation.
reverse direction. That device is adapted to pass about
Either one of the devices, It}, 11, 24, or 32, as illustrated
three times as much current (12) because it contains con
siderably more radioactive material. When no ambient 20 in FIGS. 1, 2 and 4, may be used in these positions.
Source of potential 12 is connected across both of the
ionizing radiation is being received, the voltages are rep
components 49 and 41, and the positive terminal is con
resented by the intersection 2t; of curves A and B applying
nected in series with a high resistor 21 to the movable
about 6 volts across device 11 and about 200 less 6 or 194
blade 2% of the switch 18A. This form of switch includes
volts across chamber 10.
When penetrating radiation is incident upon the ioniza 25 tWo electrodes 22 and 42 which are used exclusively for
setting up an electrostatic ?eld. Switch 18A also in
tion chamber 19, causing it to be more conductive than
cludes a contact 23, as before, but in this circuit it is
device 11 (curve D), the potential ditIerences across each
connected directly to the alarm 15. The storage capaci
component shift; the drop across chamber 10 becomes
tor 16 is connected between the negative terminal of the
lower while the drop across device 11 becomes higher.
source 12 and the movable switch blade 20. Electrode
This action changes the potential of contact 22 abruptly,
42 is connected to the negative terminal of source 12
raising it to a value which may be as high as 180 volts
through a protective resistor 4-3.
(with 200 volts supplied by source 12). This condition is
represented in the graph in FIG. 3 by intersection 30.
Since contact 23 is at zero potential an electrostatic ?eld
is set up between electrodes 22 and 23 and since mem
ber 20 is at 200 volts, it is attracted toward the zero poten
The operation of this circuit (FIG. 5) is similar to the
circuits described above except that when the voltage
shifts and the switch is operated, the current from the
charged capacitor 16 flows through the blade 20, through
contact 23, and through the alarm 15, back to the other
side of the capacitor 16. Since all the above described
circuits are not designed to be operated at fast repetition
ated position as shown by the dotted line in the ?gures, the
potential of the ?ring electrode in triode 13 is raised and 40 rates, the capacitor may be charged slowly with resistor
14 in FIGS. 1, 2 and 4, and resistor 21 in FIG. 5 having a
the triode conducts. Capacitor 16 now discharges
value of about 10 megohms.
through the alarm 15, operating it and giving noti?cation
It will be obvious that the above described circuits pro
that the penetrating radiation applied to chamber 10 is
tial electrode 23 While being repulsed by the positive po
tential electrode 22.
When member 20 moves to its actu
above a predetermined value.
vide an e?icient and dependable radiation alarm while
ceived by the chamber (less than the predetermined value).
FIG. 1 shows device 11 open to the atmosphere because
be understood that besides including a structure which
produces a visual or audible signal, the alarm assembly
of the cut-away portion 31 of its envelope. Small changes
may include a relay with a holding circuit or a mechanical
Curve C represents the characteristic of chamber 10 45 using negligible electrical power in the standby condition.
Details of the alarm 15 have not been shown but it will
when an intermediate amount of radiation is being re
in atmospheric pressure have very little e?ect on discharge 50 lock so that once tripped the alarm will continue to oper
ate after capacitor 16 has been discharged.
device 11 and this device generally operates well at this
The foregoing disclosure and drawings are merely illus
pressure. Since the electrodes and the space between
trative of the principles of the radiation alarm as dis
them are open to the atmosphere, smoke particles which
closed and are not to be interpreted in a limiting sense.
might be the result of a ?re can enter the space between
the electrodes and reduce the current between the elec 55 The only limitations are to be determined from the scope
trodes either by masking the alpha rays and thereby re
ducing ionization or else by causing recombination of the
ionized gas molecules.
In either case the current through
of the appended claims.
What is claimed is:
1. A radiation alarm for indicating the presence of
penetrating radiation above a predetermined value com
device 11 is lowered causing a large change of voltage
similar to the operation described above and the alarm is 60 prising; an ionization chamber having an anode and a
cathode within a permeable envelope; said chamber ar
again operated.
The circuit shown in FIG. 2 is the same as FIG. 1 ex
cept that a photoelectric cell 24 is used as a circuit compo
nent instead of the constant current device 11. The pho
ranged to pass current which is proportional to the inten
sity of the penetrating radiation incident thereon but pass
ing constant current in response to a wide range of ap
toelectric cell 24 is enclosed in a light tight shield 25 hav 65 plied voltages; a constant current device in series with
the ionization chamber and a source of potential; said
ing access to the atmosphere through a series of ba?le
‘constant current device including an anode, a cathode,
plates 26. A small quantity of luminescent material 27 is
and a source of constant ionization within an envelope; an
positioned adjacent to the cell 24 and causes a constant
electrostatic switch having a movable switch blade posi
current to flow through the cell. Under such conditions,
photoelectric cells possess constant current characteristics 70 tioned adjacent to a stationary plate and a switch con
tact; a connection between the stationary plate and the
similar to device 11. The operation of this circuit is simi
junction between the ionization chamber and the con
lar to the operation of the circuit shown in FIG. 1. When
stant current device; said movable blade connected to the
smoke passes through the shield ba?le plates it cuts off the
anode of the ionization chamber in series with a resistor;
light from material 27 and causes an abrupt shift in volt
75 a gaseous discharge device having an anode, a cold cath
age across chamber 10 and cell 24.
ode, and a control electrode positioned within an envelope
containing an ionizable gas at reduced pressure; said con
trol electrode connected to said switch contact; an alarm
connected in series between the cathode of said discharge
device and the negative terminal of the source of poten
tial; and a connection between the anode of said discharge
device and the positive terminal of the source of potential
in series with a resistor.
2. A radiation alarm as set forth in claim 1 wherein
said control electrode is connected to the negative termi 10
nal of the source of potential in series with a resistor.
3. A radiation alarm as set forth in claim 2. wherein
said ionization chamber contains a source of ionizing
4. An alarm circuit according to claim 2 wherein said 15
constant current device includes two electrodes and is
open to the atmosphere, the resistance between said elec
trodes changing when smoke particles enter the space be
tween the electrodes.
5. An alarm circuit according to claim 2 wherein said
alarm is adjusted to operate when the gaseous discharge
is rendered conductive and to be non-operative when the
discharge device is not conductive.
References Cited in the ?le of this patent
Banneitz ______________ __ Nov. 9,
Tour _______________ __ June 12,
Donelian ____________ __ Sept. 24,
Meili ________________ __ Feb. 22,
Shamos ______________ __ Dec. 24,
Без категории
Размер файла
483 Кб
Пожаловаться на содержимое документа