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Get» E, 19460
Filed Aug. 30, 1941
dams EVANS
Patented Oct. 1, 1946
John Evans, Palmyra, N. 1., assignor to Radio
Corporation of America, a corporation of Dela
- Application August 30, 1941, Serial No. 408,961
6 Claims.
My present invention relates to electric dis
charge devices, particularly cathode ray tubes
and has for its principal object to provide an im
(Cl. 250-167)
potential in each thermocouple T. These sepa
rate potentials are proportional to the instan
taneous intensity of the rays which impinge
proved apparatus for visually indicating the pres
thereon. As in conventional practice, the sig
ence of an object in darkness by utilization of
5 nal plate P is connected to ground through a sig
invisible emanations from said object.
nal coupling resistor RI and since the cathode C
It Will be appreciated by those skilled in the art
of the electron gun G from which the scanning
to which my invention appertains that every ob
beam X emanates is connected to ground, as in
ject has an instantaneous temperature which dif
dicated at R2, the separate potential which is set
fers from the temperature of its background by
an increment determined by the thermal lag 10 up in each thermocouple is isolated until the cir
cuit between the electron gun and the said ther
of said object. It follows, therefore, that invisi
mal elements is completed by Way of the electron
ble rays are continuously emanating from all ob
beam. Thus, during the scanning cycle the po
tential difference in each thermal element is se~
My present invention contemplates the appli
.cation of principles heretofore employed in tele 15 quentially caused to appear across the signal re
sistor Rl. The potential difference across this
vision systems, in the conversion of such invisible
output resistor is thus proportional to the in
rays into a visible image of the object from which
stantaneous intensity of the invisible rays which
the said rays emanate. The prinicipal difficulty
impinge thereon, provided only that the thermal
encountered in the application .of television
methods to such use resides in the fact that the 20 coupling between the separate thermocouples T
by way of the signal plate P is not such as to pro
“mosaic” electrodes employed in conventional tel
duce a state of thermal equilibrium. To obviate
evision transmitting tubes are not responsive to
the possibility of thermal equilibrium, I make the
rays of a wave length below the visible portion of
the spectrum.
backing plate B as thin as possible, commensu
Accordingly, another and important object of 25 rate with mechanical strength.
In making a thermal-responsive image-cathode
my invention is to provide a “mosaic” electrode
of novel construction and which is sensitive to
rays of a wave length below the visible portion
of the spectrum.
Other objects and advantages, together with 30 thermal-responsive elements T. I prefer to make
this temporary support B of cellulose acetate or
certain details of construction,
equivalent synthetic plastic material and to form
and my invention itself will be best understood
it by pouring a solution of the plastic material
by reference to the following speci?cation and
upon a body of water and subsequently lowering
to the accompanying drawing wherein:
the water level so that the resultant ?lm is de
posited upon a suitable frame Fl (Fig. 2). When
this ?lm or membrane 13 is thoroughly dry, I
a signal plate P thereon, preferably in
accordance with the principle of my invention,
vacuo, as by evaporating or otherwise depositing
Figure 2 is a longitudinal sectional view of 40 thereon a thin layer or ?lm of gold, platinum or
other non-oxidizable or di?icultly oxidizable met
the said mosaic electrode during an intermedi
Figure l is a partly diagrammatic View of a
television transmitting tube incorporating a
thermoelectric mosaic electrode constructed in
ate stage of its manufacture.
My invention contemplates the provision in an
otherwise conventional television transmitter
tube T of an image cathode M comprising a mul
tiplicity of physically discrete thermocouples T
mounted upon an electrically conductive base or
“signal plate” P. The invisible image to be tele
vised is focused upon the said thermoelectric sur
face of the mosaic as by means of a suitable lens
system which is exempli?ed in the drawing by
a single lens L which may be constituted of rock
salt or other suitable substance. The invisible
rays, of which the image is constituted, set up a 55
deposit, through the interstices in the screen, two
layers Bi and sb, respectively, of different metals
selected from the thermo-electric series. I prefer
to use bismuth and antimony, in either order, as
these metals lie at the extremes of the thermo
electric series and hence give rise to the maxi
mum thermo-electric effect, though I may employ
other of the thermo-electrically “positive” and
“negative” metals selected from the group or se
ries comprising bismuth, platinum, lead, tin, cop
per, gold, silver, zinc, iron and antimony.
wherein said electrically conducting surface com»
prises a ?lm-like structure constituted of a rela
I subsequently remove the half tone screen
from the now sensitized signal plate P and ?t a
second frame F2 over the bottom frame FI and
clamp it securely in place as by means of screws
S. I then remove the temporary supporting sur
face 13 as by dissolving it with arnyl acetate or
other suitable solvent, taking care not to punc
ture or otherwise damage the signal plate P or
the discrete thermocouple T thereon. In ac
tively non-oxidizable metal.
4. The method of making a heat responsive
image cathode which comprises forming a syn
thetic plastic material into a temporary base for
said cathode, depositing a thin layer of a non
oxidizable metal on a surface of said temporary
base, forming a multiplicity of discrete thermo
. couples upon said metal layer, providing the re
taching the necessary electrical lead W to the. ‘
sultant structure with a permanent frame and
now otherwise completed image cathode of my in
vention I make the connection to that frame sec
tion (F2) which is in direct'contact with the sig
thereafter dissolving said temporary plastic base.
5. A picture transmitting tube comprising an
image cathode comprising an electrically con
ducting‘ surface‘ having a multiplicity of ther
mocouples thereon, means for producing an elec
nal plate Pl rather than directly’ to‘; the said
plate and thereby avoid the difficulties incident to
af?Xing the lead to this ?lm-like surface.
Various modi?cations of the. apparatus . and.
method of my invention will suggest themselves
. tron beam, "and means for scanning said thermo
It is to be understood ‘
to those skilled in the art.
therefore that the foregoing is to be interpreted
couples with said- electron beam.
6; A'picture transmitting tube having an im
age cathode comprising an electrically conducting
surface‘ and a multiplicity‘of discretely mounted
as illustrative and not in» a limiting sense except
thermocouples'thereon, means-to impress heat
as _required by the spirit of the appended claims.
What is claimed is:
rays on said cathodewhereby a difference of ‘po.
tential proportionate‘ to the intensity of the im->
pinging rays is set up in said discrete thermo
couples, an output terminal for said thermocou
1.. An > image cathode adapted to respond 'to
rays belowthe visible spectrum, saidcathode com
prising an- electrically conducting surface having‘
a multiplicity of discrete elemental areas thereon‘
formed of -a plurality of superimposed layers'con
stituted ~ of di?'erent metals selected from- the
electron beam whereby ‘to causetlie potential difé >
30 ferencein each of’ said thermocouples to be se-
thermoelectric series.
2.~The-invention as set forth in claim l-and
wherein said-‘metallic layers comprise bismuth
ples connected to said conducting surface, means
in said tube for producing an electron beam; and
means-for scanning said thermocouples with- said
3: The invention as set'forth in claim 1 ‘and
quentially transferred through said conducting
surface to said output terminal.
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