EP0250053A2 - Verfahren zur Regeneration von Kathodenstrahlröhren - Google Patents

Verfahren zur Regeneration von Kathodenstrahlröhren Download PDF

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Publication number
EP0250053A2
EP0250053A2 EP87201145A EP87201145A EP0250053A2 EP 0250053 A2 EP0250053 A2 EP 0250053A2 EP 87201145 A EP87201145 A EP 87201145A EP 87201145 A EP87201145 A EP 87201145A EP 0250053 A2 EP0250053 A2 EP 0250053A2
Authority
EP
European Patent Office
Prior art keywords
grid
volts
cathode
tube
aging
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP87201145A
Other languages
English (en)
French (fr)
Other versions
EP0250053A3 (de
Inventor
Samuel Sunwhee Chung
Charles Henry Rehkopf
Frankling George Reigel
Donald Louis Siefker
James Richard Stowe
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Philips North America LLC
Original Assignee
US Philips Corp
North American Philips Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by US Philips Corp, North American Philips Corp filed Critical US Philips Corp
Publication of EP0250053A2 publication Critical patent/EP0250053A2/de
Publication of EP0250053A3 publication Critical patent/EP0250053A3/de
Ceased legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/44—Factory adjustment of completed discharge tubes or lamps to comply with desired tolerances
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/44—Factory adjustment of completed discharge tubes or lamps to comply with desired tolerances
    • H01J9/445—Aging of tubes or lamps, e.g. by "spot knocking"

Definitions

  • This invention relates to the aging of cathode ray tubes, and more particularly relates to an improved aging process in which dark center cathodes caused by the aging of the focusing electrode are substantially reduced.
  • This processing begins after assembly of the tube components, and includes: exhausting and baking the tube to evacuate the envelope and outgas the tube components; flashing a getter onto the internal surfaces of the tube and components to provide continuous gettering of residual contaminants which are outgassed during tube operation; activating the cathodes of the electron gun by heating to promote the formation of low work function species in the emission layer; aging the cathode and lower grid elements of the gun to maintain cathode activation; and finally high voltage conditioning of the electron gun to remove particles and projections which could lead to interelectrode arcing.
  • the rate of outgassing is time and temperature dependent, and the throughput demands of the manufacturing process as well as the limited thermal stability of certain tube components make complete outgassing during exhausting and baking impractical. Thus, some residual gas and gas-­producing contaminants, such as hydrocarbons, remain in the tube after sealing of the exhaust tubulation.
  • Getter flashing usually introduces additional hydrocarbon contaminants into the tube. These hydrocarbons cannot be effectively adsorbed by the non-bakable barium getters commonly employed in many types of colour television picture tubes. However, during subsequent aging, these hydrocarbons are dissociated into getterable components, resulting in the reduction of residual gas in the tube to acceptable levels.
  • An object of this invention is to reduce the incidence of dark center cathodes in a manner which does not result in unacceptably high gas levels.
  • Another object of this invention is to age a cathode ray tube after sealing and getter flashing without producing dark center cathodes, and simultaneously reduce residual gas to an acceptable level.
  • a process for aging a cathode ray tube after the tube has been evacuated, sealed and getter flashed, and the cathode has been activated comprising applying predetermined voltages to the cathode heaters and G1 grid of the tube's electron gun, so as to result in the emission of electrons from the cathodes, and then sequentially adding predetermined voltages to the G2 and G3 grid electrodes of the gun, respectively, the G2 and G3 grid voltages being larger than the cathode and G1 grid voltages; characteri­zed in that the G3 grid voltage is smaller than the G2 grid voltage.
  • the G3 grid electrode is at least 100 volts, and at least 50 volts less than the G2 grid electrode.
  • the G2 and G3 grids are connect­ed to the same potential source, and the lower G3 grid potential is achieved by inserting a resistor between these two electrodes.
  • Fig. 1 is a sectioned view showing the essential elements of a plural beam in-line colour cathode ray tube 11 aged in accordance with the process of the present invention.
  • Cathode ray tube 11 is oriented to have a central longitudinal axis 14 and X and Y axes normal to axis 14.
  • the encompassing tube envelope is a glass structure comprised of a hermetically sealed integration of neck 13, funnel 15 and viewing panel 17 portions.
  • Disposed on the interior surface of the viewing panel is a patterned cathodoluminescent screen 19 of stripes or dots of colour-emitting phosphor materials.
  • a multi-opening structure 21, in this instance an apertured mask, is positioned within the viewing panel in spaced relationship to the patterned screen 19.
  • a unitized plural-­beam in-line electron gun assembly 23 from which emanate three electron beams, a center beam 25 and two side beams 27 and 29 in a common in-line plane. These beams are directed and focused to traverse the apertured mask 21 and converge at screen 19 to excite the colour-emitting phosphors.
  • the exterior surface of the tube has an electri­cally conductive coating 31, applied to the forward region of the funnel 15, and maintained at ground potential during tube usage.
  • the plural gun assembly 23 is positioned within the neck portion 13 in a manner whereby the three in-line beams 27, 25 and 29 are in a common horizontal "in-line" plane substantially coincident with the X axis of the tube.
  • the gun assembly is a longitudinal construction of a plurality of spatially-related unitized in-line apertured electrode members.
  • the electrodes are positioned in a spaced, sequential arrangement forward of individual electron emitting cathode elements to form, focus and accelerate each of the individual electron beams.
  • the assembly is forwardly terminated by a convergence cup 39, and the whole structure is integrated by at least two oppositely disposed insulative multiform members, only one of which, 41, is shown.
  • a getter container 35 is supported by a wand 37 attached to a convergence cup 39.
  • a thin layer of getter material, not shown, was flashed from container 35 by induction heating, and covers portions of the inner surface of the envelope, mask and other tube components.
  • a unitized bi-potential electron gun assembly comprises a plurality of unitized in-line apertured electrode members sequentially positioned forward of individual cathode elements, K1, K2, K3.
  • the bi-potential electrode arrangement includes an initial beam forming grid G1, and initial beam accelerating grid G2, a main focusing grid G3 having a longitudinal dimension defined by rearward and forward apertured ends and a final accele­rating grid G4.
  • a unitized quadri-potential in-line gun assembly has a plurality of electrodes positioned forward of individual cathode elements K1, K2, K3, including an initial beam forming grid G1, an initial beam accele­rating grid G2, a first high focusing grid G3, a low focusing grid G4 electrically connected to the G2 grid, a second high focusing grid G5 electrically connected to the G3 grid, and a final accelerating grid G6.
  • Each of the G3, G4 and G5 grids has a longitudinal dimension defined by forward and rearward apertured ends.
  • cathode ray tubes It is a standard practice in the manufacture of cathode ray tubes to subject the cathodes and lower grid elements of the electron gun to an aging treatment subsequent to exhausting, baking, sealing and getter flashing the tube. Such aging takes place immediately after the cathodes are activated, and prior to high voltage conditioning. Aging has at least two objectives in addition to preparing the emission layer itself, both of which are directed to maintaining cathode activation and thereby insuring adequate electron emission from the cathodes.
  • the first object of aging is to "condition" the surfaces of the adjacent grid elements, that is, heat the grids to remove particles, adsorbed gases and other residue which are potential sources of cathode contamination.
  • the second object of aging is to convert residual gases, mainly hydro-carbons, into getterable species. This is done by selecting the voltages on the cathode and various grid elements so as to result in an electron beam of sufficient energy to dissociate these residual gas molecules into smaller components.
  • FIG. 4 A typical prior art schedule for activating the cathodes and aging the tube for a 19V mini-neck colour picture tube having a quadripotential focus electron gun is illustrated graphically in Fig. 4.
  • Heater filament and G1, G2 and G3 grid potentials are plotted versus time in minutes.
  • the heater filaments are initially subjected to a relatively low potential (E F ) of about 6.5 volts for about 1 minute to preheat the cathodes, and then the heater voltage is raised to about 9.5 volts for about 1 minute to activate the cathodes. Aging begins immediately after activation.
  • E F relatively low potential
  • a voltage of about 8.5 volts is maintained on the cathode heater filaments throughout the 33 minute aging cycle.
  • the G1 grid is subjected to a slightly lower potential of about 8 volts.
  • the G1 grid potential is increased to about 15 volts, and the G2 grid is subjected to a substantially higher potential of about 300 volts.
  • the G2 potential is increased to 350 volts, and 11 minutes after the EG1 is reduced to 10 volts.
  • the G3 grid is subjected to a potential of about 350 volts for about 13 minutes.
  • E F is maintained for about 1 minute after EG1, EG2 and EG3 have been turned off, and is subsequently reapplied for an additional two minutes to insure against the formation of detrimental deposits on the cathodes from the grids, and to further reduce any contaminants on the cathode surface.
  • FIG. 7 An arrangement for achieving the above activating and aging schedule is shown schematically in Fig. 7, wherein potential source E F supplies the cathode heater filaments, source EG1 supplies the grid G1 and source EG2 supplies both the G2 and G3 grids.
  • the actual potential values for each gun element being aged are controlled by the values of the resistors.
  • Typical values for resistors RK1-3 for example, are 150 ohms each, for RG1, 100 ohms, and for RG2, 5000 ohms. Since there is no resistor between G2 and G3, these grids are subjected to the same potential.
  • the G3 grid when the G3 grid is subjected to a potential similar to that of G2, the positively charged carbon particles resulting from the dissociation of residual hydrocarbons are formed into a beam and directed back onto the cathodes, forming dark center cathodes similar to that illustrated in Fig. 5, wherein cathode 90 includes carbon deposit 92 in the center of emissive layer 94.
  • the potential of the grid G3 In order to avoid such detrimental deposits, the potential of the grid G3 must be lowered to create a barrier to the positively charged particle beam.
  • lowering the potential of the grid G3 too far can have at least two adverse effects. First, it reduces the effectiveness of gas dissociation, by reducing the energy of electron beam. Second, it reduces the effec­tiveness of G3 grid conditioning, by reducing the temperature produced by energy dissipation in the grid. Both residual gas and contaminants on the G3 grid can find their way to the cathodes during later tube operation, reducing emission and consequently shortening tube life.
  • the G3 potential should be at least 100 volts, and at least 50 volts below the G2 potential, and preferably at least 150 volts and at least 100 volts below the G2 potential.
  • EG2 was reduced to 400 volts, and a 5000 ohm resistor (RG3 in Fig. 8) was inserted into the circuit between the grids G2 and G3, resulting in poten­tials of 325 and 255 volts at the grids G2 and G3, respectively.
  • the currents flowing to the grids G2 and G3 were 0.5 and 15 milliamps, respectively.
  • Emission and emission slump are reported for each of the red, green and blue guns. Emission is reported in micro­amperes as an average ( ) of 10 to 12 samples, with standard deviations ( s ). Emission slump is reported as percent decrease in emission after 5 seconds at a filament potential of 5 volts and zero bias. Appearance of the cathodes after aging was visually rated as zero, light, moderate and heavy deposits, and reported without distinc­tion between individual guns.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Manufacture Of Electron Tubes, Discharge Lamp Vessels, Lead-In Wires, And The Like (AREA)
EP87201145A 1986-06-19 1987-06-16 Verfahren zur Regeneration von Kathodenstrahlröhren Ceased EP0250053A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US87615086A 1986-06-19 1986-06-19
US876150 1986-06-19

Publications (2)

Publication Number Publication Date
EP0250053A2 true EP0250053A2 (de) 1987-12-23
EP0250053A3 EP0250053A3 (de) 1990-03-28

Family

ID=25367087

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87201145A Ceased EP0250053A3 (de) 1986-06-19 1987-06-16 Verfahren zur Regeneration von Kathodenstrahlröhren

Country Status (4)

Country Link
EP (1) EP0250053A3 (de)
JP (1) JPS6324530A (de)
KR (1) KR880001015A (de)
CA (1) CA1304774C (de)

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3966287A (en) * 1975-06-27 1976-06-29 Rca Corporation Low-voltage aging of cathode-ray tubes
JPS61110935A (ja) * 1984-11-05 1986-05-29 Toshiba Corp 陰極線管の製造方法

Also Published As

Publication number Publication date
KR880001015A (ko) 1988-03-30
JPS6324530A (ja) 1988-02-01
CA1304774C (en) 1992-07-07
EP0250053A3 (de) 1990-03-28

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