Classifications

• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C3/00—Glass compositions
  • C03C3/04—Glass compositions containing silica
  • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
  • C03C3/095—Glass compositions containing silica with 40% to 90% silica, by weight containing rare earths
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C3/00—Glass compositions
  • C03C3/04—Glass compositions containing silica
  • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
  • C03C3/102—Glass compositions containing silica with 40% to 90% silica, by weight containing lead
  • C03C3/105—Glass compositions containing silica with 40% to 90% silica, by weight containing lead containing aluminium

Definitions

• the requirements relative to the maximum permissible distortion of the glass are in this case much more stringent in connection therewith than for glass of envelopes for monochrome display.
• the temperature at which the tube must be heated during evacuation and sealing must be approximately 20 higher and the heat treatment is of a longer duration than for the tubes for monochrome display.
• the glasses within the above-mentioned range are eminently satisfactory in a technological respect relative to the softening point, the quality and the thermal coefficient of expansion.
• the absorption of these glasses for the X-ray radiation generated during operation as a result of the electron bombardment on the glass and on the shadow mask is sufficiently great. This even applies when the tube is built in in a cabinet in direct vision construction, thus without a protective cover glass.
• the intensity of the transmitted X-ray radiation may be at most 0.5 milliroentgen per hour (mr/h) at a maximum thickness of l 1 mm of the screen glass, an acceleration voltage of 27.5 k. volt and an anode current of 300 [.LA in a television display tube.
• the temperature dependence of the viscosity is not too great.
• the temperature difference between the softening point, which is the temperature at which the viscosity of the glass is poises, and the annealing point, which is the temperature at which the viscosity of the glass is 10 poises must be at least 190 C.
• glass for a color display tube has an annealing point which is not lower than 485 C.
• a glass for a color television display tube has approximately the same coefficient of expansion as that of the known glasses (approximately 99 X 10" between 30 and 300 C.), so that a better match is obtained with the existing glasses and metal components which must be sealed on or in respectively.
• a content of PbO is present with an approximately equal BaO content relative to the known glass. It is by no means surprising in itself that the absorption of X-ray radiation is increased as a result thereof. It was, however, not obvious that it was possible to maintain the physical properties of the glass at the same level by means of a few other modifications. Furthermore, it is also known (from U. K. Pat. specification No. 664,769) that no discoloration occurs on the glass of the faceplate due to electron bombardment, provided that the glass contains Ce0 and provided that the glass contains no more than 1 percent of readily reducible oxides. However, the glass according to the invention which does not satisfy the last-mentioned requirement owing to its content of PbO, does not discolor under the influence of the electron bombardment.
• the softening point of these glasses lies between 690 and 710 C.; the annealing point between 485 and 510 C. and the thermal coefficient of expansion is approximately 97 to 100 X 10 between 30 and 300 C.
• the glasses according to the invention amply satisfy the above-mentioned requirement of transmitting at most 0.5 mr/h at an acceleration voltage of 35 K.volt; it was found that this amount was not yet reached at an acceleration voltage of even 44 to 45 k.volt when using these glasses.
• the electric resistance thereof is at least 10" ohm. cm and at least 10 ohm.cm at 250 and 350, respectively, while these values are 10* and 10' ohm.cm for the abovementioned known glasses.
• the following glass is an example of a glass suitable for the relevant purpose. It is obtained in a manner which is common practice in glass technology by melting the relevant oxides or compounds which are converted into the oxides.
• Glass for envelopes of television display cathode-ray tubes particularly intended for the face-plate of the tube, consisting essentially of the following in percent by weight:

Landscapes

• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Glass Compositions (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=19805028

Family Applications (1)

Country Status (10)

Cited By (7)

Citations (3)

• 1968
  • 1968-10-29 NL NL6815397A patent/NL6815397A/xx unknown
• 1969
  • 1969-10-21 DE DE1952922A patent/DE1952922C3/de not_active Expired
  • 1969-10-22 US US868611A patent/US3663246A/en not_active Expired - Lifetime
  • 1969-10-24 GB GB1238133D patent/GB1238133A/en not_active Expired
  • 1969-10-27 BR BR213674/69A patent/BR6913674D0/pt unknown
  • 1969-10-27 AT AT1009669A patent/AT289217B/de not_active IP Right Cessation
  • 1969-10-27 FR FR6936757A patent/FR2021805A1/fr not_active Withdrawn
  • 1969-10-27 ES ES372917A patent/ES372917A1/es not_active Expired
  • 1969-10-28 BE BE740926D patent/BE740926A/xx unknown
• 1976
  • 1976-10-14 HK HK639/76*UA patent/HK63976A/xx unknown

Patent Citations (3)

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