US3297898A - Mercury support cup for cold cathode mercury vapour tube - Google Patents

Mercury support cup for cold cathode mercury vapour tube Download PDF

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Publication number
US3297898A
US3297898A US338999A US33899964A US3297898A US 3297898 A US3297898 A US 3297898A US 338999 A US338999 A US 338999A US 33899964 A US33899964 A US 33899964A US 3297898 A US3297898 A US 3297898A
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US
United States
Prior art keywords
tube
mercury
cup
terminal
globule
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.)
Expired - Lifetime
Application number
US338999A
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English (en)
Inventor
Dobbins David Woods
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.)
SIGNCRAFTS Ltd
Original Assignee
SIGNCRAFTS Ltd
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 SIGNCRAFTS Ltd filed Critical SIGNCRAFTS Ltd
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Publication of US3297898A publication Critical patent/US3297898A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/04—Electrodes; Screens; Shields
    • H01J61/06—Main electrodes
    • H01J61/067—Main electrodes for low-pressure discharge lamps
    • H01J61/0672—Main electrodes for low-pressure discharge lamps characterised by the construction of the electrode
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/24—Means for obtaining or maintaining the desired pressure within the vessel

Definitions

  • the mercury globule is introduced by a tubulation into the cold zone in which it is trapped by the mica disc.
  • mercury vapour is able to flow through the two small pipes in the centre of the disc, but the mercury globule itself is prevented from passing through them because they project into the cold zone above the level of the globule when resting on the wall of the cold zone.
  • This invention provides a terminal tube suitable for fixing to the end of a mercury vapour discharge tube and containing an electrode and a liquid mercury holding chamber having an entry surrounded by a re-entrant flange shaped to deflect a mercury globule into the chamber when the tube is titlted in one direction and thenceforth to retain the globule in the chamber during subsequent tilting of the tube in any direction.
  • the mercury can be introduced into the manufactured tube at any desired point along its length, either at the junction between the terminal tube and the display tube or at a tubulation extending through the closed end of a terminal tube. Because the liquid mercury globule is prevented by the re-entrant flange from flowing from the holding chamber the useful life of the display tube may be materially increased.
  • FIGURE 1 shows in partial section a terminal tube fused to one end of a fluorescent display tube
  • FIGURE 2 shows, in plan, the entry of a re-entrant cup
  • FIGURE 3 is a section through the cup taken on the line indicated by the arrows III-III in FIGURE 2;
  • FIGURES 4 to 8 show a modified re-entrant cup in five different positions to illustrate its ability to retain a mercury globule within it.
  • the terminal tube comprises a glass tube 1 having an internal diameter of /2-inch and a wall thickness of about -inch.
  • One end of the terminal tube is open and fused at 2 to one end of a display tube 3 and the other end of the terminal tube is closed by a pinch 4 through which pass two connecting wires having diminished diameters where they pass through the pinch.
  • the wires terminate outside the pinch in two electrical terminals 6 and inside the pinch in two further pins 7 which pass axially through the centre of a thin, metal cup 8, defining a mercury holding chamber, and which are welded to the rear end of a tubular iron electrode 9 of hollow form and about l A-inches long.
  • the electrode 9 is supported axially in the terminal tube by the attached pins 7.
  • the end of the electrode adjacent the pins and the cold zone 10 is closed, and the other end is open and terminates in an annular ceramic disc 11 which prevents sputter from the end of the electrode 9 whilst in use.
  • the re-entrant cup 8 has a rounded conical base 12 in contact with the rear of the electrode 9 and is crimped at its centre 13 t0 the support pins 7.
  • the periphery of the base 12 merges into a cylindrical side wall 14 coaxially disposed in the terminal tube 1 and one-sixth of an inch in length.
  • An annular gap 15 of about & of an inch is left between the cylindrical side wall 14 of the cup 8 and the inner surface of the terminal tube 1.
  • the cylindrical side wall 14 terminates in the cold zone 10 in a rounded rim 5 which merges into a frusto-conical re-entrant flange 16 which is peened-in and is approximately parallel to the bulging conical base 12 of the cup.
  • the inner edge 17 of the flange 16 defines a circular central entry 18 to the cup of about one-fifth of an inch diameter and through the centre of which the support pins 7 pass.
  • the open end of the terminal tube 1 is fused at 2 to the edge of a hole in one end of the display tube 3 which is internally coated with a layer of fluorescent material adapted to fluoresce under ultra-violet light generated by ionization of mercury vapour in the tube.
  • the mercury is admitted to the discharge tube after cleaning through a fine bore pipe 20 fused into the junction between the terminal tube 1 and the display tube. After a mercury globule has been admitted through the pipe 20 it is sealed and cut short.
  • the discharge tube is then tilted so that the mercury globule runs down the terminal tube 1, past the electrode 9, and through the annular gap 15 between the cylindrical side wall 14 of the cup 8 and the inner wall of the terminal tube 1 to the pinch 4 at the end of the cold zone 10.
  • the discharge tube is then turned upside-down so that the mercury globule flows back from the closed end of the cold zone 10 towards the electrode 9 and is deflected by "ice the inwardly directed frusto-conical flange 11 of the cup to the entry 18 in the centre thereof.
  • the mercury lodges in the holding chamber as shown at 21 in FIGURE 1 and is held therein by the re-entrant flange 16 irrespective of the angle of tilt at which the tube is subsequently held.
  • FIGURES 4 to 8 show a modified mercury holding chamber 30 in five diflerent positions.
  • the holding chamber 30 is similar to the re-entrant cup 8 except that it is provided with a ring of perforations 31.
  • the perforations 31 comprise a number of small circular holes of inch diameter which are sufliciently large to allow mercury vapour to pass easily through them but are too small to allow a mercury globule 32 to pass through.
  • the mercury vapour is able to flow easily into the display tube while the mercury globule is safely held within the chamber 30. From the five views shown in FIGURE 4 it will be seen that the mercury globule 32 is safely held irrespective of the angle to which the chamber 30 is tilted.
  • the invention provides a mercury trap which is simple to manufacture, is applicable to all known ways of introducing mercury into the tube and is capable of holding the liquid mercury globule in the cold zone of the tube during fixing of the tube in position and throughout the useful life of the tube.
  • a cold cathode discharge tube comprising: a display tube, a terminal tube fused to said display tube, wires extending through a pinch at the closed end of the terminal tube, an electrode mounted inside said terminal tube and supported by said wires, a re-entrant cup defining a mercury holding chamber and mounted on said wires between the electrode and the closed end of the tube, and a flange defining an entry to the cup and extending inwardly thereof from its outer wall which is spaced from the inner wall of the terminal tube by a narrow gap of suflicient width to allow a globule of mercury to pass therethrough towards the closed end of the tube when the terminal tube is tilted in one direction but sufliciently narrow to result in the mercury globule being deflected by the flange into the entry to the cup when the terminal tube is tilted in the reverse direction.

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  • Vessels And Coating Films For Discharge Lamps (AREA)
US338999A 1963-01-21 1964-01-20 Mercury support cup for cold cathode mercury vapour tube Expired - Lifetime US3297898A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB246063 1963-01-21

Publications (1)

Publication Number Publication Date
US3297898A true US3297898A (en) 1967-01-10

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Family Applications (1)

Application Number Title Priority Date Filing Date
US338999A Expired - Lifetime US3297898A (en) 1963-01-21 1964-01-20 Mercury support cup for cold cathode mercury vapour tube

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US (1) US3297898A (enrdf_load_stackoverflow)
GB (1) GB1054181A (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0715338A1 (en) * 1994-12-01 1996-06-05 Masonlite Limited Apparatus for providing radiation
US20070216308A1 (en) * 2006-03-16 2007-09-20 Kiermaier Ludwig P Lamp electrode and method for delivering mercury
US20070216282A1 (en) * 2006-03-16 2007-09-20 Kiermaier Ludwig P Lamp electrode and method for delivering mercury

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1764048A (en) * 1927-12-17 1930-06-17 Sun Ray Gas Corp Luminous electrical discharge tube
GB748202A (en) * 1953-04-24 1956-04-25 Philips Electrical Ind Ltd Improvements in or relating to getter holders
US2781471A (en) * 1954-09-28 1957-02-12 Ets Claude Paz & Silva Diaphragm for electric discharge tube

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1764048A (en) * 1927-12-17 1930-06-17 Sun Ray Gas Corp Luminous electrical discharge tube
GB748202A (en) * 1953-04-24 1956-04-25 Philips Electrical Ind Ltd Improvements in or relating to getter holders
US2781471A (en) * 1954-09-28 1957-02-12 Ets Claude Paz & Silva Diaphragm for electric discharge tube

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0715338A1 (en) * 1994-12-01 1996-06-05 Masonlite Limited Apparatus for providing radiation
US5754000A (en) * 1994-12-01 1998-05-19 Masonlite Limited Apparatus for providing radiation
US20070216308A1 (en) * 2006-03-16 2007-09-20 Kiermaier Ludwig P Lamp electrode and method for delivering mercury
US20070216282A1 (en) * 2006-03-16 2007-09-20 Kiermaier Ludwig P Lamp electrode and method for delivering mercury
US7288882B1 (en) 2006-03-16 2007-10-30 E.G.L. Company Inc. Lamp electrode and method for delivering mercury

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GB1054181A (enrdf_load_stackoverflow)

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