EP0378338A2 - Entladungsröhre - Google Patents

Entladungsröhre Download PDF

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Publication number
EP0378338A2
EP0378338A2 EP90300190A EP90300190A EP0378338A2 EP 0378338 A2 EP0378338 A2 EP 0378338A2 EP 90300190 A EP90300190 A EP 90300190A EP 90300190 A EP90300190 A EP 90300190A EP 0378338 A2 EP0378338 A2 EP 0378338A2
Authority
EP
European Patent Office
Prior art keywords
electrode
discharge
filament
sintered metallic
set forth
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.)
Granted
Application number
EP90300190A
Other languages
English (en)
French (fr)
Other versions
EP0378338B1 (de
EP0378338A3 (de
Inventor
Yoriyuki Nieda
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.)
TOKYO DENSOKU KK
Original Assignee
TOKYO DENSOKU KK
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 TOKYO DENSOKU KK filed Critical TOKYO DENSOKU KK
Publication of EP0378338A2 publication Critical patent/EP0378338A2/de
Publication of EP0378338A3 publication Critical patent/EP0378338A3/de
Application granted granted Critical
Publication of EP0378338B1 publication Critical patent/EP0378338B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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

Definitions

  • the present invention relates to a discharge tube having a positive glow discharge characteristic in which the tube voltage increases as the discharge current increases and a negative arc discharge characteristics in which the tube voltage decreases as the discharge current increases due to an increase in emission of thermo­electrons.
  • Cold-cathode tubes have positive discharge characteristics and have the advantages of long life, low power consumption, low heat dissipation, and the ability to be easily lit and quenched.
  • the disadvantage of cold-cathode tubes is their low intensity.
  • Hot-cathode tubes which are known as fluorescent lamps, have negative thermionic discharge characteristics and the advantage of high intensity. Hot-cathode tubes, however, have the disadvantages of short life, high power consumption, high heat dissipation, and cannot be lit and quenched in themselves.
  • Semi-hot-cathode tubes are arranged such that no filament electrode is energized by external circuits and have the disadvantage that a relatively long time is required to reach the desired intensity after energization. Also, semi-hot-cathode tubes are impractical in terms of life and intensity.
  • the present inventor proposes a discharge tube of the type having a discharge characteristic in which the negative discharge characteristic of a cold-cathode tube is combined with the positive discharge characteristic of a hot-cathode tube. More specifically, the proposed discharge tube comprises a pair of electrode assemblies which are dis­posed opposite each other in a discharge space. Each of the electrode assemblies includes a cup-shaped electrode for glow discharge and, a filament electrode for arc discharge which is disposed in the cup-shaped electrode. This arrangement is intended to achieve long life with glow discharges and very high brightness with arc dis­charges. However, it is necessary that such discharge tube be provided with an automatic control circuit for controlling discharge current in order to stably maintain the state of discharge.
  • a discharge tube in which a pair of opposite electrode assemblies are disposed in a gas-charged discharge space which is, at least in part, defined by a glass wall.
  • each of the electrode assemblies is provided with a sintered metallic electrode for emitting electrons and a filament electrode coated with oxide for emission of thermoelectrons, and the sintered metallic electrode and the filament electrode are arranged close to each other and electrically connected in parallel.
  • Each of the opposite electrode assemblies which are arranged at both ends of the discharge space, includes an electrode for glow discharge and an electrode for arc discharge, which are arranged side by side. Accordingly, when a voltage from the same high-frequency electric source is applied to these electrodes, high-­intensity arc discharge and glow discharge are stably formed in the discharge space at the same time, whereby a very high intensity of 35,000 Nt or more is obtained by the synergistic effect of the arc discharge and the glow discharge. For instance, if metal, such as nickel, is used for electrodes for glow discharge, stable glow discharge will be obtained up to a current level of about 3 mmA.
  • Fig. 1 shows a first embodiment of a discharge tube according to the present invention.
  • a rod-like sintered electrode 2 and a filament coil electrode 3 are disposed at each end of a transparent glass tube 1 which has a diameter of approximately 6 mm and a length of approximately 260 mm.
  • the rod-like sintered electrode 2 and the filament coil electrode 3 are arranged in parallel and close to each other, i.e., in a non-contact state.
  • Each of the rod-­like electrodes 2 has a diameter of 2 mm and a length of 6 mm and is prepared by mixing tungsten powder, zirconium, nickel and barium carbonate, forming the mixture with a press, and sintering the formed mixture.
  • Each of the filament coil electrodes 3 has a good electron emission characteristic and is prepared by coating a solution of barium hydroxide over the peripheral surface of a tungsten wire, sintering the tungsten wire to form a coat of barium carbonate, and forming it into a coil.
  • each of these electrodes 2 and 3 is supported by a tungsten wire or rod-like member 7 and connected to one end of a lead wire 8 via the tungsten rod-like member 7.
  • One end of each of the lead wires 8 extends into the glass tube 1 through a glass end wall thereof.
  • the inner surface of the glass tube 1 is coated with a fluorescent film 4 and the interior of the glass tube 1 is charged with argon gas pressurized at a pressure of 30 torr and 5 mmg of mercury 6.
  • a strip or trigger coating 9 is formed on the outer surface of the glass tube 1 to extend along the length thereof.
  • a lead wire 10 is led from the trigger coating 9 and connected to the lead wire 8 which is led from one end of the glass tube 1.
  • the other ends of the respective lead wires 8 are connected to an A.C. power source 11.
  • Fig. 2 shows a discharge tube according to one modification of the first embodiment shown in Fig. 1.
  • the same reference numerals are used to denote the same elements as those shown in Fig. 1.
  • This modifi­cation differs from the first embodiment in that each filament coil electrode 3a is arranged to surround a corresponding rod-like sintered electrode 2a in a non-contact state.
  • a highly stable discharge can be achieved with a discharge current of 20 mA and an intensity of 35,000 Nt.
  • the temperature of the tube wall of the portion of the dis­charge tube which is adjacent to each electrode assembly is approximately 15 degrees higher than room temperature and the amount of heat generated can be reduced compared to conventional arrangements. Accordingly, it is possible to reduce power consumption.
  • a discharge-tube driving circuit can be made compact.
  • Fig. 3 shows another modification of the first embodiment, and only an electrode assembly which differs from that shown in Fig. 2 is illustrated.
  • This modification is similar to the modification of Fig. 2 in that a rod-like sintered electrode 2b is surrounded by a filament coil electrode 3b, but the filament coil electrode 3b is densely coiled in cup-like form with each of its ring segments held in close contact with the adjacent ring segment.
  • Fig. 4 shows still another modification of the first embodiment, and an electrode assembly which differs from that shown in Fig. 3 is illustrated.
  • a sintered metallic electrode 2c for glow discharge is formed into a cup-like shape, and a filament coil electrode 3c for arc discharge extends straight along the axis of the assembly.
  • the cup-like electrode 2c may be formed into the shape of a hollow cylinder with a bottom.
  • any of the discharge tubes according to the first embodiment have a glass-tube diameter of about 4 mm to about 10 mm.
  • the sintered electrode shown in Fig. 4 there can be used an electrode formed in such a way that a nickel or tungsten wire is densely coiled in a shape similar to that of the electrode 3b shown in Fig. 3 while coating a nickel or tungsten powder over the peripheral surface of the coiled wire. Further, then the filament coil electrode 3c is set at the center of the thus-formed electrode.
  • a sine-wave oscillating voltage was applied across the discharge tube shown in Fig. 2 under the following conditions: charged gas : a mixed gas containing argon gas of 50 torr and 5 mmg of mercury; oscillation frequency : 40 kHz; and ambient temperature : room temperature (15°C)
  • glow discharge was started between the opposite sintered electrodes at 400 rmsV, and the filament coil electrodes started discharges at approximately 500 rmsV. Even if the voltage was raised to 500 rmsV or more, a positive discharge characteristic was maintained between the sintered electrodes. In other words, it was proved that the glow discharge could be maintained even at a voltage level of 500 rmsV or more. In addition, it was proved that, at a voltage level of 500 rmsV or more, a negative discharge characteristic could be obtained between the filament coil electrodes, whereby arc discharge could be maintained.
  • the two kinds of discharge, glow discharge and arc discharge are realized within a single discharge tube, very high intensity of illumination can be achieved. Also, since the filament coil electrodes are heated by glow discharge, arc discharge can be generated by using a relatively low voltage. In addition, since the two kinds of electrodes are arranged in a non-contact state, the sintered metallic electrodes are not heated by the heat generated in the adjacent filament coil electrodes. Accordingly, since no thermorunway takes place in the sintered metallic electrodes, glow discharge does not proceed with arc discharge and the glow discharge can be kept highly stable between the sintered metallic electrodes.
  • Each of the filament coil electrodes is coated with an active oxide such as barium, strontium or the like in order to accelerate emission of thermoelectrons. Accordingly, particles may be scattered due to evaporation or peeling caused by ion bombardment or heating and fall on the inner tube wall of the discharge tube, thereby causing the shading phenomenon in which dark shades are formed on the inner tube wall of the discharge tube.
  • the cup-shaped sintered metallic electrode shown in Fig. 4 is employed, scattered particles stick to the inner wall of the cup-shaped sintered metallic electrode and the stuck particles or active oxide can be reused.
  • the lifetime of the discharge tube can be improved.
  • the present inventor conducted a lifetime test with a discharge tube having such electrode assemblies, and the shading phenomenon was not substantially observed even after running of 10,000 hours or thereabouts.
  • Fig. 6 shows a second embodiment of the present invention.
  • a discharge tube which is made from a flat discharge plate configured like a flat box.
  • the illustrated discharge plate includes a top glass plate 1a, a bottom glass plate 1b and a glass frame spacer 11.
  • Each of the glass plates 1a and 1b has one surface coated with a fluorescent film, and the glass plates 1a and 1b are stacked with their coated surfaces facing each other.
  • the glass frame spacer 11 is sandwiched between the top and bottom glass plates 1a and 1b.
  • the glass plates 1a and 1b and the glass frame spacer 11 are bonded by glass solder, thereby forming a discharge space.
  • the discharge space is charged with discharge gas consisting of a mixture of argon gas 5 pressurized at several tens of torr and several milligrams of mercury 4.
  • a rod-shaped sintered metallic electrode 2d and a filament coil electrode 3d are arranged in parallel and close to each other at each end of the discharge space.
  • the filament coil element 3d is formed into a rod-like configuration in whcih a tungesten coil, coated with oxide metal having good electron-emission characteristics, is densely coiled.
  • a trigger conductive plate or film 9a is bonded to the external surface of the bottom glass plate 2a.
  • the discharge plate having the above construc­tion also exhibits characteristics similar to those of the discharge tube shown in Fig. 2. More specifically, with the above second embodiment, it is possible to provide a surface light source having the following advantages: glow discharge and arc discharge can coexist so that very high intensity, long life and low power consumption can be achieved; lighting and quenching are easy; the amount of heat generated is small; and highly stable operation is assured.
  • Fig. 7 shows a modification of the second embodiment of Fig. 6, and only an electrode assembly which differs from that used in the above second embodi­ment is illustrated.
  • the illustrated electrode assembly is arranged in such a manner that a filament coil electrode 3e for arc discharge is wound around the periphery of a sintered electrode 2e for glow discharge in a non-contact state.
  • Fig. 8 shows another modification of the second embodiment, and a tungsten wire electrode 3f for arc discharge is disposed along the axis of a half-cylindrical sintered electrode 2f.
  • This modification also makes it possible to achieve advantages similar to those of the discharge tube shown in Fig. 4.
  • Fig. 9 shows a third embodiment of the discharge tube of the present invention.
  • the third embodiment is substantially the same as the embodiment of Fig. 2 except that a top glass plate 1c and a bottom glass plate 1d have ribs 12a and 12b formed on their facing surface, respectively.
  • the above second embodiment makes it possible to obtain a postcard-size surface light source made from a glass plate with a plate thickness of approximately 4 mm.
  • the thickness of the glass plate also increases to an impractical extent.
  • the ribs 12a and 12b are formed as in the second embodiment, the strength of each of the top and bottom glass plates 1c and 1d can be increased to a considerable extent. Accordingly, a surface light source having a light weight and a considerably large size can be obtained.
  • the discharge impedance in each of the gaps A and B becomes high and the discharge space is substantially divided into a plurality of small dis­charge spaces X, Y and Z.
  • Electorde assemblies E are respec­tively arranged at the opposite ends of each of the small discharge spaces X, Y and Z, whereby a discharge plate is obtained which is constructed as if a plurality of discharge tubes were arranged side by side.
  • Fig. 10 shows a modification of the third embodiment, wherein ribs 12c and 12d are densely formed on glass plates 1e and 1f, respectively.
  • electrode assemblies Ea each of which is similar to that shown in Fig. 8, are disposed and a multiplicity of electrode assembly pairs are arranged in small discharge spaces, respectively.
  • Each of the end plates has a trough-like configuration so as to accommodate the electrode assemblies Ea. This arrange­ment also makes it possible to provide a discharge characteristic similar to that of the discharge plate of Fig. 9.
  • sintered metal is used for the electrodes for glow discharge. Although intensity is somewhat low, nickel may also be used.
  • thermoelectrons is accelerated and rapid lighting (several tens of seconds) is enabled.
  • the electrodes for arc discharge can be heated by the respective electrode assemblies themselves, no external preheating device is needed and power consump­tion can be reduced to a considerable extent. In addi­tion, the amount of heat generated can be reduced.
  • the electrodes for glow discharge are not forced to the state of arc discharge and stable discharge can therefore be achieved.

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  • Discharge Lamp (AREA)
  • Lasers (AREA)
EP90300190A 1989-01-12 1990-01-08 Entladungsröhre Expired - Lifetime EP0378338B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP5753/89 1989-01-12
JP1005753A JPH02186551A (ja) 1989-01-12 1989-01-12 放電管

Publications (3)

Publication Number Publication Date
EP0378338A2 true EP0378338A2 (de) 1990-07-18
EP0378338A3 EP0378338A3 (de) 1991-06-12
EP0378338B1 EP0378338B1 (de) 1997-04-02

Family

ID=11619881

Family Applications (1)

Application Number Title Priority Date Filing Date
EP90300190A Expired - Lifetime EP0378338B1 (de) 1989-01-12 1990-01-08 Entladungsröhre

Country Status (4)

Country Link
EP (1) EP0378338B1 (de)
JP (1) JPH02186551A (de)
KR (1) KR920010057B1 (de)
DE (1) DE69030333D1 (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0467713A2 (de) * 1990-07-19 1992-01-22 Tokyo Densoku Kabushiki Kaisha Entladungsröhre
EP0560063A1 (de) * 1992-02-28 1993-09-15 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Niederdruckentladungslampe
US5585694A (en) * 1990-12-04 1996-12-17 North American Philips Corporation Low pressure discharge lamp having sintered "cold cathode" discharge electrodes
EP1271616A2 (de) * 2001-06-25 2003-01-02 Bing Lin Yang Beleuchtung für Entladungslampe
CN102427016A (zh) * 2011-07-13 2012-04-25 株式会社上一系统 照明用冷阴极型荧光灯

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2599192Y2 (ja) * 1990-07-19 1999-08-30 東京電測 株式会社 放電管

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2046941A (en) * 1934-10-27 1936-07-07 Gen Electric Gaseous electric discharge device
US2314134A (en) * 1942-01-08 1943-03-16 Colonial Lighting Co Inc Gaseous discharge device
CH319769A (de) * 1953-03-06 1957-02-28 Mueller Felix Ing Dr Elektrode für Entladungsgefässe
JPS5750760A (en) * 1980-09-13 1982-03-25 Matsushita Electric Works Ltd Electrode for discharge lamp
WO1987004562A1 (en) * 1986-01-17 1987-07-30 Sidefact Limited Flat light source
EP0343625A2 (de) * 1988-05-27 1989-11-29 Toshiba Lighting & Technology Corporation Einseitig gequetschte Metallhalogenidlampe

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2046941A (en) * 1934-10-27 1936-07-07 Gen Electric Gaseous electric discharge device
US2314134A (en) * 1942-01-08 1943-03-16 Colonial Lighting Co Inc Gaseous discharge device
CH319769A (de) * 1953-03-06 1957-02-28 Mueller Felix Ing Dr Elektrode für Entladungsgefässe
JPS5750760A (en) * 1980-09-13 1982-03-25 Matsushita Electric Works Ltd Electrode for discharge lamp
WO1987004562A1 (en) * 1986-01-17 1987-07-30 Sidefact Limited Flat light source
EP0343625A2 (de) * 1988-05-27 1989-11-29 Toshiba Lighting & Technology Corporation Einseitig gequetschte Metallhalogenidlampe

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, vol. 6, no. 123 (E-177), 8th July 1982, page 1001; & JP-A-57 050 760 (MATSUSHITA) 25-03-1982 *
Philips: Het Internationale Eenhedensystem (SI-eenheden) volgens UN-D 21 voor straling en licht. Philips (November 1976). *

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0467713A2 (de) * 1990-07-19 1992-01-22 Tokyo Densoku Kabushiki Kaisha Entladungsröhre
EP0467713A3 (en) * 1990-07-19 1992-11-19 Tokyo Densoku Kabushiki Kaisha Discharge tube
US5585694A (en) * 1990-12-04 1996-12-17 North American Philips Corporation Low pressure discharge lamp having sintered "cold cathode" discharge electrodes
EP0560063A1 (de) * 1992-02-28 1993-09-15 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Niederdruckentladungslampe
EP1271616A2 (de) * 2001-06-25 2003-01-02 Bing Lin Yang Beleuchtung für Entladungslampe
EP1271616A3 (de) * 2001-06-25 2003-12-10 Bing Lin Yang Beleuchtung für Entladungslampe
US7004809B2 (en) 2001-06-25 2006-02-28 Bing Lin Yang Illuminant for discharge lamp
CN102427016A (zh) * 2011-07-13 2012-04-25 株式会社上一系统 照明用冷阴极型荧光灯
AT511690A1 (de) * 2011-07-13 2013-01-15 Sang Il System Co Ltd Kaltkathodenfluoreszenzlampe mit hoher effizienz und langer bestrahlungsdauer
GR1007827B (el) * 2011-07-13 2013-02-08 Sang Il System Co. Ltd, Λαμπτηρας φθορισμου ψυχρης καθοδου για φωτισμο
ES2402160R1 (es) * 2011-07-13 2013-11-04 Sang Il System Co Ltd Lámpara fluorescente de cátodo frío para iluminación

Also Published As

Publication number Publication date
KR920010057B1 (ko) 1992-11-13
EP0378338B1 (de) 1997-04-02
JPH02186551A (ja) 1990-07-20
DE69030333D1 (de) 1997-05-07
KR900012321A (ko) 1990-08-03
JPH0546048B2 (de) 1993-07-12
EP0378338A3 (de) 1991-06-12

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