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Патент USA US2128581

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ârag. EQ, 35333
Unirse l sra’res
2,323,581
eared?
_A ' caries
Bernard c. Genauer, rhnmìerphia, ra.; :serena
to Farnsworth Television incorporated. San
Francisco, Calif., a corporation of California
_ _application may is, 193s. ser-nx No. 30,33:
>2 Gianna (C1. 25o-21.5)
This invention relates to a method and appa>ratus'ior the production of electron beams oí
canal type, providing
entry_port as at 2. ptli-l A
sitioned to receive electrons from the concave
very small cross secrìonarea. and particularly to surface. of cup l. to the hollow cylindrical canal
ill. A diaphragm H_is secured over the exit end
~an inherently accurate method whereby -the elec
tron beams produced maybe made 'asï small as 4 of the 'anode and serves _todeflne the cross sec
tional area oi -afbean'iv .passing therethrough
toward _the screen!` .`
'
Prment methods of producingr a restricted elec'
The grid 5` may be ringïsh-aped'and ís mounted .
tron beamA employe diaphragmvprovidedwith an
desired.
.
n
apertureof asìze'suñicient to pass. the» -desired
-with the axis 'of the anode and~ ln line with the 19
formed is frequently imperfect. Slight imperfec
feci: in small beams than in large. It is also true
‘in operation, electrons freed iron: the emitter
S, areshot through the anode by applying suf
ñcìent voltage between the anode and the cathode,
th'at'assmailer beams are required proper aline
ment oí the parts oí apparatus become practically
tive potential with respect to the cathode and
- tions in the apertures have more pronounced ef
is
impossible, and-the difhculty of constr'mxting-apu
paratus _by presenty methods for very small beam.
production is prohibitive from a practical stand
20
point.
-
'
It is the principal object of my invention to
provide a practical and economical method of
producing electron beams of very small cross
section.
~ Another object of my invention is to provide an
efñcientA and elîectìve method ol“ providing an
electron beam diaphragm with an aperture oí
any desired degree of minuteriess.
‘
A further object of my invention is to pro
30 vide a new and novel method of constructing an
electron beam producing apparatus.
Another object of my invention is to provide
improved apparatus for the production of elec
tron beams oí very small cross section and of
35 high quality.
'
Y
electron emitting substance. such as anoxide of
barium or strontium. carried on the concave sur
face of a cup l', which cup is ln turn positioned
ln heat-receiving relation to a filament B. Any
suitable source of current may be provided for
l
55
"
'
'
.
The grid 5 may be maintained at a. slightly nega
15p-à
serves to direct the electrons toward port 9 of the
anode. The ûeld through which the electrons
pass into the canal of the cylindrical anode tends
to focus the electron beam at the azls oí the dia
phragm end o1' the anode. the electrons passing
through the canal in. straight. slightly converging
lines along the axis oí the cylinder. The aper
ture i2 of the diaphragm should have its center
at the focal center of the beam -so that the most 25
effective portion oí the bearn may be milked,
the portions of the diaphragm surrounding the
aperture serving to catch the fringe electrons d'
the beam, and permitting only e sharply defined
beam to pass -`oe3«'o1'ui'the diaphragm. The beam. 3o.
'so produced' may be utilized to produce a curve.
on the screen 2 under control of dellector plates
i3 in a well known manner.
-
Heretofore the aperture i2 has been drilled
fixing the cathode. anode, and grid 'in operative
a. fluorescent screen' 2 upon which an electron
l
_
relation in the tube. The result has been that
accurate alinement of the aperture with the cen.
trai axis of the electron beam required consid
beam is projected by an electron gun or the like.
Such guns-are well known in the art and may
comprise a. cathode 3. an anode d, and a gridvB.
The cathode may in turn comprise a ñlm 6 of an
i
.
` orl otherwise etîected in the diaphragm prior to _
`
The drawing illustrates a tube I provided with
ì.
-
parent as the description proceeds in connection
with the accompanying ldrawing; in which the
invention»
l
cathode.:-
Other objects and advantages will-become ap
single ligure illustrates a cathode ray tube con.
structed in accordance vwith the principles oi my
l
l
with itsaxis-ias.nearlyas- _possible in coincidence
Thä'e apertures are drilled. in the dia
phragm but it is found that the aperture so
10 beam.
erable adjustment and precision in assembly, and
even so, an absolute alinement was most often
impossible. à very slight misallnernent may re
suit in the beam being partially, if not entirely.
directed upon the diaphragm rather than
through its aperture.
,
.
In accordance with my invention. the aperture
l2 l5 formed in the diaphragm il after, not be
fore, the cathode and anode are placed in as
sembled relation. During assembly a thin me~
tallic> diaphragm il, of some such material as
molybdenum or nickel. having no aperture there
ln, is welded or otherwise fastened over the exit
energizing filament 8,' which. when heated, frees ' end of the beam canal l0. .The assembled tube
ls then evacuated. The cathode is then heated
electrons from the emitting substance.
.
The anode i may be oí the well known beam and a. voltage applied to the anode i with the
2
f
-
`
,amaai
nection with a specific form oi apparatus it will
result
on the that
diaphragm
s, beam i!
o! at
electrons
_the spot
is at whim an
aperture should be mede. .es the roiîage on the
be understood that the disclosure is illustrative
only and that man3 other applications o! rrrv
anode is increased, the spot
‘by _the
electrons is correspondingly heated and, with
invention will loccur to those skiiîed In the ari.
Accordingiv, applicant considers himseii' en 5
titled to ali such applications. modifications. and
suiiicient. heatingA of this character. the eia
phragm is punctured. Since the maximum heat
ing occurs at the point. of greatest electron carb'
vm
eentra'tlon.- the resuitant vpuncture is properìy
located, and, if the .anode voltage is reduced ím
I claim:
1. in a cathode ray tube Awherein a beam of 1B
medîately after the puncture occurs, the apemu'e
electrons is projected through an apermred
anode, the method of forming said aperture which
remains smaìi. The sue of the aperture may be
increased as desired by simply continuing the
_comprises forming said anode without an aper
process so as to further melt the edges of the
ture therein, focusing a beam o'í electrons on l.
aperture until an aperture of the desired size is
predetermined spot on said anode, acceierating 15
said electrons until `the anode is' pierced at the
area of electron impact, and thereafter project
produced.
The Yoîtages used to puncture the diaphragm
À are large compared to, normal operating voltages.
ing electrons through said aperture and utilizing l
Accordingly no change in aperture size oc'curs in
normal operation.
Forming the diaphragmpaperture in this man
variations
the scope of his
the invention
appended.as
claims,
properly he .
said latter electrons.
‘
2. In _a cathode ray tube wherein abeam of
electrons is projected .through an'apertured
ner insures precision in aiinernent with' com
anode. the method of forming said apertura
paratively iittie eñ'ort- and it 'also permits ‘lha which comprises îorzning’ a beam canal 'in ~said
making oi`very minute apertures, for itis evi~ _mode closing one'lenri of >said beam
di
dent that the ñrst passage >of >-electrons.’ through ` rectingeiectrons into the open end of said' beam
25
the diaphragm during the piercing- stepî‘oecm's
' canal; accelerating said electrons to ìínpact the' ,
at the-,center‘of 'the beam. The fact of» the pas` ciosed'endwith sufñcìent velocity to reopeniiie
sage is ’immediateb' evident on the .screen` and v beam canal’ by melting- andY vaporiz‘atìori,v and
the size of the-spot on the screen serves 'ás an.
indication of the size of the aperture.
While-.I have disclosed my invention in oo_n
thereafter passing electrons through said open
ing to obtain an indication.
‘
BERNARD C. GARDNER
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