EP0405816A2 - Entladungsröhrensystem - Google Patents

Entladungsröhrensystem Download PDF

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Publication number
EP0405816A2
EP0405816A2 EP90306639A EP90306639A EP0405816A2 EP 0405816 A2 EP0405816 A2 EP 0405816A2 EP 90306639 A EP90306639 A EP 90306639A EP 90306639 A EP90306639 A EP 90306639A EP 0405816 A2 EP0405816 A2 EP 0405816A2
Authority
EP
European Patent Office
Prior art keywords
discharge tube
launcher
tube according
discharge
section
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.)
Withdrawn
Application number
EP90306639A
Other languages
English (en)
French (fr)
Other versions
EP0405816A3 (en
Inventor
Ulrich Greb
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.)
Thorn EMI PLC
Original Assignee
Thorn EMI PLC
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 Thorn EMI PLC filed Critical Thorn EMI PLC
Publication of EP0405816A2 publication Critical patent/EP0405816A2/de
Publication of EP0405816A3 publication Critical patent/EP0405816A3/en
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J65/00—Lamps without any electrode inside the vessel; Lamps with at least one main electrode outside the vessel
    • H01J65/04—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels
    • H01J65/042—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels by an external electromagnetic field
    • H01J65/044—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels by an external electromagnetic field the field being produced by a separate microwave unit

Definitions

  • This invention relates to a discharge tube arrangement and in particular, though not exclusively, to such an arrangement for use as a light source.
  • this invention relates to a discharge tube for such a discharge tube arrangement.
  • EP 0225753A discloses two types of discharge tube.
  • One type is cylindrical as in conventional discharge tube arrangements.
  • the other type of tube is tapered with a reducing taper from the end connected to the energizer (ie launcher) to the opposite end.
  • the surface wave energy is absorbed in the discharge tube as it travels from one end to the other, less energy is needed by each additional increment of tube length for a given amount of brightness at any location along the tube length since the tube diameter is smaller.
  • Such a tube accordingly produces a uniform radiation output.
  • an electrodeless discharge tube containing an ionizable fill, said tube comprising a first portion for insertion in a launcher, said tube further comprising a further portion having a dissimilar cross-section from the cross-section of said first portion.
  • the inventors have surprisingly discovered that it is possible to sustain a surface wave discharge in a discharge tube in which one portion has a dissimilar cross-section from another so that the cross-section of the discharge tube changes not only in size but also in type.
  • the dimensions of a transitional portion intermediate the first portion and the further portion are advantageously chosen so as to alleviate the problem of reflection of the surface wave from the wall of the tube.
  • Discharge tubes provided in accordance with the present invention can be used to produce plasmas of a variety of geometries.
  • the first portion of the discharge tube is of circular cross-section and so can be accommodated in conventional launchers.
  • a discharge tube arrangement comprises a discharge tube 1 (shown in part) mounted in a launcher 2.
  • the discharge tube 1 is formed of a light-transmissive, dielectric material, such as glass, and contains a fill 4 of a noble gas, such as argon and an ionizable material, such as mercury.
  • the launcher 2 is made of an electrically conductive material, such as brass, and formed as a coaxial structure comprising an inner cylinder 6 and an outer cylinder 8.
  • Dielectric material 9 is provided inside the launcher 2, inter alia to hold the inner cylinder 6 in position within the outer cylinder 8.
  • a first plate 10, at one end of the outer cylinder, provides a first end wall for the launcher structure.
  • a second plate 11, integral with the outer cylinder 8, provides a second end wall.
  • the inner cylinder 6 is shorter than the outer cylinder 8 and so positioned within the outer cylinder 8 as to define a first annular gap 12 and a second annular gap 13.
  • Each of the first plate 10 and second plate 11 has an aperture for passage of the discharge tube 1.
  • the outer cylinder 8, the first plate 10 and the second plate 11 form an unbroken electrically conductive path around, but not in electrical contact with, the inner cylinder 6 to provide an r.f. screening structure therearound.
  • Suitable dimensions for the launcher of Figure 1 are as follows: Launcher length 7-20mm Launcher diameter (outer cylinder 8 diameter) 25-35mm but depends on size of discharge tube 1. Inner cylinder 6 length 3-18mm Inner cylinder 6 diameter 13mm but depends on size of discharge tube 1. Length of launching gap (first gap 12) 0.5 - 3mm Length of second gap 13. 1-10mm.
  • the thickness of the electrically conductive material is of the order of millimetres, or less, depending on the method of construction used.
  • An r.f. power generator 14 (shown schematically) is electrically connected to the launcher 2 via a coaxial cable 15 and an impedance matching network 16 (shown schematically) consisting of capacitors 17 and inductors 18.
  • the r.f. power generator 14, the impedance matching network 15, the coaxial cable 18 and the launcher 2 constitute an r.f. powered excitation device to energise the gas fill to produce a discharge.
  • an oscillating electric field having a frequency typically in the range of from 1MHz to 1GHz, is set up inside the launcher 2.
  • this electric field is parallel to the longitudinal axis of the tubular portion of the discharge tube 1. If sufficient power is applied, the consequent electric field produced in the gas fill 4 is sufficient to ionise the mercury to create a discharge through which an electromagnetic surface wave may be propagated in a similar manner to the arrangement of EP 0225753A. Accordingly, the launcher 2 powered by the r.f.
  • power generator 14 creates and sustains a discharge in the gas fill - the length and brightness of the discharge depending, inter alia, on the size of the discharge tube 1 and the power applied by the r.f. power generator 14. Such a discharge tube arrangement may therefore be used as a light source.
  • the first gap 12 and the second gap 13 each extend axially from respective ends of the inner cylinder 6, respectively to the first plate 10 and second plate 11.
  • both the first and the second gaps 12, 13 are effective as launching gaps to create a discharge. If the first and second gaps 12, 13 are the same size, this results in a relatively symmetric discharge.
  • FIG. 2 shows a second embodiment of a discharge tube arrangement.
  • the launcher 20 is formed as a coaxial structure in a similar manner to the launcher 2 of Figure 1 and accordingly like parts are designated by like reference numerals.
  • No aperture is provided in the second plate 11 and accordingly a discharge tube 22 (shown in part) extends from one side of the launcher 20 only.
  • the second gap 13 complements the effect of the first gap 12, which, as the launching gap, creates the discharge.
  • the second gap 13 is, in this embodiment, advantageously larger than the launching gap 12.
  • the r.f. power at the second gap 13 is dissipated in the discharge and not lost from the system as in prior art launchers.
  • Electrodeless discharge tubes provided in accordance with the present invention and which can be used with the discharge tube arrangements of Figures 1 and 2 are shown in Figures 3, 4, 5 and 6.
  • Figure 3a is a plan view of an electrodeless discharge tube 30 and Figures 3b and 3c are views of the discharge tube 30 of Figure 3a looking in the directions IIIB-IIIB and IIIC-IIIC respectively.
  • the discharge tube 30 comprises a first portion 32 of circular cross-section, and an intermediate portion 34 tapering into a further portion 36 of rectangular cross-section.
  • the dimensions, d31, d32 of the further portion 36 transverse to the axis of the cylindrical portion 32 are greater than the diameter D3, i.e. the transverse dimension, of the cylindrical portion 32.
  • the further portion 36 presents a rectangular surface.
  • Figure 4a is a plan view of an electrodeless discharge tube 40 and Figures 4b, 4c and 4d are views of the discharge tube 40 of Figure 4a looking in the directions IVB-IVB, IVC-IVC and IVD-IVD respectively.
  • the discharge tube 40 comprises a first portion 42 of circular cross-section, an intermediate portion 44 and a further portion 46 of rectangular cross-section which presents a rectangular surface.
  • the maximum dimension d41 of the further portion 46 transverse to the axis of the cylindrical portion 42 is greater than the diameter D4 of the cylindrical portion 42.
  • the minimum transverse dimension d42 of the further portion 46 is orthogonal to its maximum dimension d41 and is less than the diameter D4 of the cylindrical portion 42.
  • Discharge tube arrangements incorporating the electrodeless discharge tubes of Figures 3 and 4 can be used in a variety of applications. Examples include providing backlighting as a large planar light source or creating a uniform plasma over a large surface for non-lighting applications such as plasma coating/etching etc.
  • Figure 5a is a plan view of an electrodeless discharge tube 50 and Figures 5b and 5c are views of the discharge tube 50 of Figure 5a looking in the directions VB-VB and VC-VC, respectively.
  • the discharge tube 50 comprises a first portion 52 of circular cross-section and a further portion 54 which presents a triangular surface.
  • the maximum transverse dimension d51 of the triangular portion 54 is greater than the diameter D5 of the cylindrical portion 52.
  • a discharge tube arrangement incorporating such a discharge tube can be used in a variety of applications. One example is to provide a thin strip of light of width d52 from the face 56 of the discharge tube 50.
  • Figure 6a is a sectional view of an electrodeless discharge tube 60 and Figure 6b is a view of the discharge tube 60 looking in the direction VIB-VIB.
  • the discharge tube 60 comprises a first portion 62 of circular cross-section and a further portion 64 having an annular cross-section presenting an annular face 66.
  • discharge tube arrangements incorporating the launcher of Figure 1 can be fitted with electrodeless discharge tubes in which a further portion of a required shape extends from each end of the portion of circular cross-section.
  • the discharge tube arrangement may be provided with a helical wire wound around the discharge tube.
  • the helical wire is earthed and extends along the discharge tube.
  • first portions of circular cross-section for insertion into a launcher with a structure incorporating an inner cylinder as described with relation to Figures 1 and 2. If a launcher of another configuration is used, then this should be used with electrodeless discharge tubes having a first portion so shaped as to fit inside the inner body of the launcher.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Discharge Lamps And Accessories Thereof (AREA)
EP19900306639 1989-06-27 1990-06-19 A discharge tube arrangement Withdrawn EP0405816A3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB898914722A GB8914722D0 (en) 1989-06-27 1989-06-27 A discharge tube arrangement
GB8914722 1989-06-27

Publications (2)

Publication Number Publication Date
EP0405816A2 true EP0405816A2 (de) 1991-01-02
EP0405816A3 EP0405816A3 (en) 1991-07-24

Family

ID=10659120

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900306639 Withdrawn EP0405816A3 (en) 1989-06-27 1990-06-19 A discharge tube arrangement

Country Status (3)

Country Link
EP (1) EP0405816A3 (de)
JP (1) JPH0337953A (de)
GB (1) GB8914722D0 (de)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE665275C (de) * 1935-07-30 1938-09-26 Eccard Fuerst Gasentladungsleuchtroehre mit kapillarem Entladungskanal fuer Indikatorzwecke bei Hochspannungsanlagen
US2265323A (en) * 1932-07-13 1941-12-09 Gen Electric Gas and metal vapor discharge tube and means for preventing flicker therein
EP0225753A2 (de) * 1985-12-10 1987-06-16 The Regents Of The University Of California Unverzüglich einsetzende und wirksame Oberflächenwellenanregung eines oder mehrerer Niederdruck-Gase
DE3617110A1 (de) * 1986-05-21 1987-11-26 Leybold Heraeus Gmbh & Co Kg Lampe fuer die erzeugung von gas-resonanzstrahlungen
EP0316189A2 (de) * 1987-11-12 1989-05-17 Yissum Research Development Company Of The Hebrew University Of Jerusalem Infrarot-Strahlungsquelle und Verfahren zur Herstellung

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2265323A (en) * 1932-07-13 1941-12-09 Gen Electric Gas and metal vapor discharge tube and means for preventing flicker therein
DE665275C (de) * 1935-07-30 1938-09-26 Eccard Fuerst Gasentladungsleuchtroehre mit kapillarem Entladungskanal fuer Indikatorzwecke bei Hochspannungsanlagen
EP0225753A2 (de) * 1985-12-10 1987-06-16 The Regents Of The University Of California Unverzüglich einsetzende und wirksame Oberflächenwellenanregung eines oder mehrerer Niederdruck-Gase
DE3617110A1 (de) * 1986-05-21 1987-11-26 Leybold Heraeus Gmbh & Co Kg Lampe fuer die erzeugung von gas-resonanzstrahlungen
EP0316189A2 (de) * 1987-11-12 1989-05-17 Yissum Research Development Company Of The Hebrew University Of Jerusalem Infrarot-Strahlungsquelle und Verfahren zur Herstellung

Also Published As

Publication number Publication date
GB8914722D0 (en) 1989-08-16
JPH0337953A (ja) 1991-02-19
EP0405816A3 (en) 1991-07-24

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