Electric lamp and discharge devices – With temperature modifier – Using liquids or fluid flow directing means
Patent
1984-10-18
1987-01-06
DeMeo, Palmer C.
Electric lamp and discharge devices
With temperature modifier
Using liquids or fluid flow directing means
313 44, 313 45, 313477R, H01J 2986, H01J 724
Patent
active
046349189
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a liquid cooling type cathode ray tube apparatus and more particularly to a liquid cooling type cathode ray tube apparatus suitable for use with a cathode ray tube of a high brightness which is used in, for example, a color video projector.
BACKGROUND ART
In a cathode ray tube of high brightness, a reproduced optical image of high brightness is formed by increasing the energy of an electron beam which impinges upon its phosphor screen.
Heat generated in the phosphor screen when an electron beam of high energy impinges on the phosphor screen or in addition thereto heat generated in such a case when the electron beam impinge on an electron beam landing position determining electrode such as a shadow mask, an aperture grille or the like which is disposed in opposing relation to the phosphor screen within a tube envelope so as to restrict the electron beam landing position relative to the phosphor screen becomes considerably great as the energy of the electron beam is increased. However, the front panel or glass panel of the cathode ray tube envelope on which the phosphor screen is formed is low in thermal conductivity so that particularly in the continuous driving of the cathode ray tube, the rise of temperature at the central portion of the glass panel which is difficult to radiate its heat becomes significant. As a result, a so-called thermal quenching takes place in the phosphor. The thermal quenching is such a phenomenon that as the temperature rises, the brightness of the phosphor is lowered. Since the degree of thermal quenching is different depending on the phosphors of respective colors, white balance becomes out of order.
The disorder of the white balance at the center of the front panel much deteriorates the picture quality so that, upon continuous driving of the cathode ray tube, in order to establish the white balance at the center of the front panel, it may be considered to adjust the brightness of the optical images of the respective colors. In this case, there occur such defects that the white balance on the peripheral portion of the front panel is destroyed and that the brightness of the whole portion can not be increased.
Such problem becomes serious in either case of a color projector in which, for example, picture images of respective colors obtained from respective monochromatic cathode ray tubes are projected in mixed state on a screen to produce a color picture image thereon or a color picture image formed of picture images of a plurality of colors is produced from the same cathode ray tube and then projected onto the screen.
Therefore, in the cathode ray tube of this kind, in order to prevent the temperature from rising to such an extent that the thermal quenching takes place on the phosphor screen even upon continuous driving thereof, its front panel must be cooled. This cooling may be carried out by using a cooling fan. In this case, the cooling fan, however, sends not only air but also dusts to the surface of the front panel of the tube envelope. Then, the dusts adhere to the panel surface to cause an apparent deterioration of brightness. In this case, there occurs also a problem of a noise of the cooling fan.
To avoid the above shortcomings, a cathode ray tube apparatus was proposed in which a transparent liquid coolant, particularly a liquid capable of easily causing convection is disposed in contact with the front panel of the tube envelope to cool the front panel.
Such liquid cooling type cathode ray tube apparatus, particularly a cathode ray tube apparatus of a closed convection type is shown in FIG. 1, for example, as a partially cross-sectional side view. Such cathode ray tube apparatus comprises a tube envelope 1, a front panel 1a of flat plate shape on the inner surface of which a phosphor screen 7 is deposited, a flat plate shaped transparent panel 2 having optical transmissivity made of glass and opposed to the front panel and a metal spacer 3 of annular frame shape having excellent thermal conductivity interposed betwee
REFERENCES:
patent: 4405949 (1983-09-01), Hockenbrock et al.
patent: 4529905 (1985-07-01), Ohkoshi et al.
patent: 4543510 (1985-09-01), Chiba et al.
Chiba Tomosuke
Kato Hiroshi
Kikuchi Masahiro
DeMeo Palmer C.
Sony Corporation
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