Cathode ray tube having an improved indirectly heated cathode
Number of patents in Portfolio can not be more than 2000
United States of America Patent
Stats
-
Dec 10, 2002
Grant Date -
N/A
app pub date -
Jun 4, 1999
filing date -
Jun 5, 1998
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A cathode ray tube includes a phosphor screen and an electron gun. The electron gun includes an indirectly heated cathode structure and plural grid electrodes in axially spaced relationship. The cathode structure includes a base metal having an electron emissive material coating and a heater for heating the base metal. The heater includes a major heating portion having a spirally wound heating wire and leg portions disposed at ends of the major heating portion, and each of the leg portions includes a first multilayer winding portion having heating wires wound spirally in plural layers and a second multilayer winding portion disposed intermediate between the major heating portion and the first multilayer winding portion and having heating wires wound in plural layers. The major heating portion and at least a portion of the second multilayer winding portion are covered with an insulating coating, the heater is welded to electrical conductors for applying a voltage thereto at the first multilayer winding portion, and the number of layers in the second multilayer winding portion is at least three and the number of layers in the first multilayer winding portion is larger than that in the second multilayer winding portion.
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