Electric lamp and discharge devices – Cathode ray tube – Beam deflecting means
Patent
1986-12-19
1988-02-02
DeMeo, Palmer C.
Electric lamp and discharge devices
Cathode ray tube
Beam deflecting means
313477R, 313479, H01J 2986, H01J 2988
Patent
active
047230908
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a cathode ray tube and more particularly to a flat type cathode ray tube.
BACKGROUND ART
In a cathode ray tube such as a cone type television tube the whole of the inner surface of its envelope from the periphery at the electron beam emitting end of an electron gun to a phosphor screen there is an inner conductive film made by coating carbon thereon. A constant high voltage is applied to the inner conductive film whereby the electron beam emitted from the electron gun can be stably directed to the phosphor screen.
The above structure was provided because when the glass surface of the cathode ray tube proper or the surface of the insulating material faces the path of the electron beam, an unstable electric charge is stored on the surface of the insulating material which may cause a disturbance of the electric field in the path of the electron beam to thereby cause a displacement of the scanning position of the electron beam and hence to generate flicker of distortion in the picture. Previously, the present assignee proposed a flat type cathode ray tube consisting of a flat glass envelope 1 whose view in perspective is shown in FIG. 1 and whose cross-sectional view is shown in FIG. 2. This glass envelope 1 is formed of first and second panel portions 2 and 3 which are opposed to each other to establish a flat space 7 therebetween. The panels are bonded together by frit-sealing and a funnel portion 4 is similarly bonded to one side of the first and second panel portions 2 and 3 by frit-sealing. The funnel portion 4 is so formed that its open end 4a of large diameter is contacted and sealed to the first and second panel portions 2 and 3 while to its open end 4b of small diameter there is welded a neck portion 5 within which an electron gun 6 is located.
The first and second panel portions 2 and 3 comprise, as shown in their exploded and perspective view in FIG. 3, main faces 2a and 3a which oppose each other and peripheral side faces 2b and 3b which extend from three side edges other than side edges bonded to the funnel portion 4. The end surfaces of the peripheral side faces 2b and 3b, which oppose each other, are frit-bonded to establish the flat space 7 between both the panel portions 2 and 3. In order that the flat funnel-shaped space of the funnel portion 4 communicate with the flat space 7, to the side edge portions of the panel portions 2 and 3 where there exist no peripheral side faces the large diameter opening 4a is contacted and sealed by frit-bonding.
On the inner surface of the face 2a of the first panel portion 2, there is formed a conductive layer 8 made of a vapor deposited aluminum film and thereon a phosphor screen 9 is formed by, for example, electrodeposition. A protective film 10 is coated on the phosphor screen 9 and a transparent conductive layer 11 made of a vapor deposited film is coated on the protective layer so as to cover the whole inner surface of, for example, the first panel portion 2. Further, on the inner surface of the funnel portion 4 there is an inner conductive film 13 made of a carbon coating film or the like. An anode button 14 for applying a high voltage is provided through the funnel portion 4, for example, at one side which is electrically connected to the inner conductive film 13. From this anode button through the inner conductive layer 13 to the transparent conductive film 11 and hence to the phosphor screen 9 and the high voltage electrode of the electron gun 6, there is applied is a high anode voltage. The face 2a of the first panel portion 2 is so curved that the phosphor screen 9 formed on its inner surface opposite the axis of the electron gun 6, as it approaches the tip end of the envelope 1, namely the side opposite to the side near the location of the electron gun 6, it comes near or intersects the tubular axis so that the electron beam emitted from the electron gun 6 impinges on the phosphor screen 9 at about its center when the electron beam is not deflected. The electron beam emitted from the electron
Maeda Makoto
Tamura Michio
DeMeo Palmer C.
Sony Corporation
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