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NOV» 5, i962
v. s. BAWDEKAR
3,662,989
THERMIONIC VALVES
Filed April 25, 1960
VAMA/V JHA/VFQRA/V/ BAWDE/TAF?
3,652,980
Patented Nov. 6, 1952
2
3,062,980
Vaman Shantararn Eawdeitar, London, England, assigner
THERMHÜNlC ‘VALVEä
to Associated Electrical Industries Limited, London,
England, a British company
and in accordance with the invention a conductor il
is connected with the upper end of the strip 8 and
abuts against the internal `surface of the envelope so as
to provide electrical connection between the getter deposi
tion and the strip 8.
Filed Apr. 25, i960, Ser. No. 24,547
Claims priority, application Great Britain Apr. 28, 1959
3 Claims. (Cl. 313-174)
Preferably the conductor il is resilient and is con
nected to the strip 8 and lead-in wire 9 by welding at
its mid point. With such a construction the valve may
be assembled by pushing ythe electrode assembly upwards
This invention relates to thermionic valves of the 10 into the envelope. This will cause the conductor .il
kind having a cathode lead extending through the upper
to press against the sides of the envelope and to bow,
end of the valve envelope.
the bowing increasing the contact area by causing the
The invention has an important application in valves
wire to lie along the inside _face ot the envelope. The
designed for use as eíiiciency diodes in television receiv
condutor il can, of course, be a wire of circular cross
ers. Such valves have in the past been subject to noise,
section or a strip.
`
`
the source 4of which has been diiiicult to trace. In such
yClearly the conductor il is only one way of carrying
valves the potential of the cathode varies between fairly
out the invention.
wide limits and is subjected to large voltage pulses. It
Whilst the embodiment `shown is the preferred Way
is, therefore, necessary to provide, between the cathode
of carrying out the invention clearly it may be modi
and heater, insulation which will stand an appreciably 20 iied, or instance, the conductor lll could be attached to
higher voltage than that normally used in thermionic
the' wire 9 at a higher position provided it lies along
valves.
lt is ialso common practice with such valves to pass
the cathode lead-in wire through the upper end of the
valve envelope.
the inside of the envelope.
lt may either be a wire `or
strip. Instead of being connected to the cathode lead,
the conductor 1l could be connected to any other lead
During the gettering, deposition oc 25 extending from the electrode assembly with a similar po
curs on the internal surface of the upper part of the
envelope and it has been `found that in practice, during
operation of the valve, there is a tendency for sparking
tential waveform to that of the top connection.
What I claim is:
l. A thermionic valve comprising an envelope, an
to `occur between the cathode lead and the getter deposit
electrode assembly located in said envelope, said elec-during the occurrence of the high voltage pulses and 30 trode assembly including at least an anode `and a cathode,
~this sparking has been found to cause the noise above
a cathode lead extending through the end of said en
referred to. lt is thought that this sparking is due to
velope, a gettering electrode located between the elec’
4the fact that the getter film assumes a potential lying
trode assembly »and the cathode lead end of said en
intermediate between that of the cathode and the anode
velope, and a grounding lead for the getter deposit ex
’and hence there will be appreciable potential Ádiiferences 35 tending between a point of low potential and that part
`between »the cathode and the getter »deposit during the
oi the inner face of the envelope between the gettering
pulses. This arcing limits the maximum voltage at which
electrode and said cathode lead end of lthe envelope on'such a valvel can be operated.
which part the getter deposit is formed.
v
The main `object of the invention is to provide an
2. A thermionic valve' comprising an envelope, an
improved construction enabling >such valves to be run at 40 electrode lassembly located in said envelope, said elec
higher voltages.
trode assembly including at least an anode and a cathode,
According to the present invention a valve of the kind
a cathode lead extending through the end `of said en
referred to is provided with an electrical Vconnection be
velope, -a gettering electrode located between the elec
tween the surface of the envelope on which getter depo
45 trode assembly and the cathode lead end yof said en
sition occurs and a point `of low potential.
velope and a grounding connection for the getter deposit
‘lt will be lappreciated that the getter deposit has a
extending between the cathode lead and that part of
degree of conductivity so that the connection need only
be made to a localised area.
the inner face of the envelope between the gettering
electrode and said cathode lead end of the envelope on
Preferably an electrical Iconnection is made between
which part the getter deposit is formed.
50
the getter deposit and the cathode lead.
3. A thermionic valve comprising an envelope, an
It has been found that such a connection appreciably
electrode assembly located in said envelope, said electrode
reduces the tendency for sparking to occur and hence
assembly including at least an anode and a cathode, a
reduces the noise generated in the valve.
cathode lead extending through the epd of said envelope,
ln order that the invention may be more clearly under
a gettering electrode located betweëh the electrode as
stood reference will now be made to the accompanying 55 sembly and the cathode lead end of said envelope and
drawing which shows an example of a valve embodying
a grounding connection for the getter deposit extending
the invention.
between the cathode lead and that part of the inner
In the drawing the reference 1 indicates a valve en
face of the envelope between thev gettering electrode and
velope, 2 is the top mica disc supporting the upper end
said cathode lead end of the envelope on which part
of the electrodes of which 3 is the anode and 4 the 60 the getter deposit is formed, said grounding lead com
cathode having an insulated heater 5 within it. Above
prising a resilient strip extending transversely across the
the disc 2 is a getter ring 6 and between the getter ring
cathode lead to which it is attached at its mid point
6 and the disc 2 is a screen 7 »to prevent getter deposi
so that the ends are pressed :resiliently `against the inner
tion reaching the electrodes.
face of the envelope.
Extending upward from the cathode is a conductor 65
References Cited in the tile of this patent
strip 8 and to this in turn is connected a lead-in wire
9 extending through the upper end of the envelope.
UNITED STATES PATENTS
The getter deposition, which is indicated by the refer
27,601,528 Ishler _______________ __ June 24,
ence l0, occurs around the upper part of the envelope
2,638,559
Giacchetti ___________ _.. May l2,
1952
1953
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