EP0253316A2 - Entladungslampe mit kalter Elektrode - Google Patents

Entladungslampe mit kalter Elektrode Download PDF

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Publication number
EP0253316A2
EP0253316A2 EP87109938A EP87109938A EP0253316A2 EP 0253316 A2 EP0253316 A2 EP 0253316A2 EP 87109938 A EP87109938 A EP 87109938A EP 87109938 A EP87109938 A EP 87109938A EP 0253316 A2 EP0253316 A2 EP 0253316A2
Authority
EP
European Patent Office
Prior art keywords
tube
discharge lamp
cathode electrode
lamp apparatus
electrode member
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Withdrawn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
EP87109938A
Other languages
English (en)
French (fr)
Other versions
EP0253316A3 (de
Inventor
Shouichi Iwaya
Hitoshi Masumura
Munemitsu Hamada
Hiromi Ohfuna Seisakusho Adachi
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.)
Mitsubishi Electric Corp
TDK Corp
Original Assignee
Mitsubishi Electric Corp
TDK 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
Priority claimed from JP1986108598U external-priority patent/JPH0514455Y2/ja
Priority claimed from JP1986108597U external-priority patent/JPH0514454Y2/ja
Priority claimed from JP1986108595U external-priority patent/JPH0512918Y2/ja
Application filed by Mitsubishi Electric Corp, TDK Corp filed Critical Mitsubishi Electric Corp
Publication of EP0253316A2 publication Critical patent/EP0253316A2/de
Publication of EP0253316A3 publication Critical patent/EP0253316A3/de
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/30—Cold cathodes, e.g. field-emissive cathode
    • 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

Definitions

  • the present invention relates to discharge lamp apparatuses, and more particularly to a cold cathode type discharge lamp apparatus.
  • a mercury lamp is known as a cold cathode type discharge lamp apparatus.
  • cathode of the mercury lamp when a switch is turned on at cold cathode state, glow discharge is started and transferred immediately to arc discharge thereby the cathode is transferred from cold cathode state to hot cathode state so as to perform the hot cathode emission.
  • Such cathode of the mercury lamp is produced in process that oxide of alkaline earth metal and other oxide having heat-resistant property are mixed, thereby electron emission material is produced and filled in a storage portion of a coil-like electrode, and then burning is applied thereto.
  • the electron emission material in the storage portion of the electron is subjected to chemical reaction due to heat and varied into material liable to evaporation, and the evaporated material is adhered to the tube wall of the light emission tube during the lighting for a long time, thereby the light emission tube is blackened and the luminous flux of the lamp is deteriorated and the life of the lamp is decreased.
  • the prior art has problems in the chemical reaction of the material on the electrode surface due to heat, the blackening of the light emission tube and decrease of the tube life.
  • an object of the invention is to provide a cold cathode type discharge lamp apparatus wherein a tube wall of a light emission tube is prevented from being blackened, and the life of the tube becomes long.
  • a cold cathode type discharge lamp of the invention is composed of a discharge lamp tube, a cathode electrode member in nearly cylindrical form made of a semiconductor porcelain and having a discharge surface on an apex, a sealing support member for sealing and supporting the cathode electrode member within the tube, and a lead wire connected to the cathode electrode member.
  • FIG. 1a A first embodiment of the invention will now be described in detail referring to FIG. 1a.
  • a discharge lamp electrode shown in FIG. 1a is composed of a tube 1 for discharge lamp, a cathode electrode member 2 using a semiconductor porcelain and arranged within the tube 1, a sealing support member 3 which seals and supports the cathode electrode member 2 within the tube 1 and near an end portion 1a of the tube 1, and a lead wire 4 which is connected to the cathode electrode member 2 and extends to outside through the sealing support member 3.
  • the cathode electrode member 2 is made of a semiconductor porcelain, and comprises a semispherical discharge surface 2a on one end portion and a base 2b of nearly cylindrical form. Center portion of the discharge surface 2b becomes an apex 2c most projecting from the base 2b. Thus the cathode electrode member 2 is in cylindrical form.
  • the sealing support member 3 is arranged penetrat­ing the end portion 1a of the tube 1, and the lead wire 4 is sealed and supported at the end portion 1a and an end portion 4a of the lead wire 4 at inside of the tube is wound on outer circumference of the base 2b, thereby the cathode electrode member 2 is supported within the tube 1 in vertical arrangement to the end portion 1a and other end portion 4b of the lead wire 4 is projected to outside from the end portion 1a of the tube 1.
  • a semiconductor porcelain as a raw material for the cathode electrode 2 will now be described in detail.
  • a valency compensation type semi­conductor porcelain may be mentioned as the semiconductor porcelain.
  • a typical example of the valency compensation type semiconductor porcelain is that using barium titanate.
  • the valency compensation as known well consists in that metal ion having valency different by value ⁇ 1 from that of constitution metal ion of metal oxide is added as an impurity, and increase or decrease of the charge quantity produced by introduction of the impurity is compensated by the number of valency of the constitution metal ion.
  • the valency compensation semiconductor forming agent can be exemplified by Y, Dy, Hf, Ce, Pr, Nd, Sm, Gd, Ho, Er, Tb, Sb, Nb, W, Yb, Sc, Ta or the like. These can be used together for adding. Adding amount of the adding agent is preferably 0.01 ⁇ 0.8 mol %, particularly 0.1 ⁇ 0.5 mol %.
  • a raw material to constitute the cathode electrode made of the semiconductor porcelain in the embodiment is preferably titanates.
  • titanates In addition to the above-mentioned barium titanate, strontium titanate, calcium titanate or lanthanum titanate may be used. Composite material of these may be used. Further, titanic acid in the titanates may be replaced by at least one of zirconic acid, silicic acid and stannic acid.
  • the semiconductor porcelain for the discharge electrode in the invention may be a forced reduction type semiconductor porcelain. This can be obtained by method of reducing the semiconductor porcelain for the cathode electrode as above described, and further by method of reducing without adding the semiconductor forming agent if the sufficient reducing condition is supplied. Reduction in this case may be performed in the reducing atmosphere of N2 or H2 and preferably in the temperature condition of 700°C or more, particularly in 1,200 ⁇ 1,450°C.
  • the electrode may be formed by using the valency compensation type and the forced reduction type together. Modes of the concurrent use are as follows:
  • Top end of a valency compensation type semiconductor porcelain was ground into conical form of about 60°, and specific resistance of the obtained semiconductor porcelain was 9.9 ⁇ cm.
  • the H2 density was made 20 % in the reducing atmosphere of H2 + N2, and the semiconductor porcelain was reduced and burned at 1,250°C and the stabilizing time 2 Hr. Specific resistance of the burned porcelain was 0.90 ⁇ cm.
  • titanic acid in the titanates was replaced by at least one of zirconic acid, silicic acid and stannic acid.
  • the device comprises a polyethylene container 5 of 15 cm in width, 5 mm in length and 10 mm in height, and silver paste 6 is applied to the bottom surface of the container 5.
  • a specimen electrode 2 ⁇ was arranged above the bottom surface and an AC power source 7 was connected between the specimen electrode 2 ⁇ and the silver paste 6.
  • Radius R at the top end arc-shaped portion of the specimen electrode 2 ⁇ is made 20 ⁇ m, and distance D between the top end portion of the specimen electrode 2 ⁇ and the silver paste 6 is made 4 mm.
  • the starting voltage was 10 kV, and the voltage was increased in 1 kV per minute.
  • the semiconductor porcelain for the cathode electrode in the embodiment has equivalent or more excellent characteristics in comparison to metals.
  • the cathode electrode 2 made of the semiconductor porcelain in the embodiment can obtain the stabilized discharge characteristics and the manufacturing cost can be decreased.
  • a second embodiment of the discharge lamp apparatus as shown in FIG. 4a comprises a discharge lamp tube 11, a cathode electrode 12 using a semiconductor porcelain and including a top end portion disposed within the tube 11, a base 12b penetrating an end portion 11a of the tube 11 and other end portion 12d projecting, a sealing support member 13 for sealing and supporting the penetrating portion of the base 12b of the cathode 12 to the end portion 11a of the tube 11, and a lead wire 14 with an end portion 14a embedded to a screw body 15 threadably engaged with the projecting end portion 12d of the cathode electrode 12.
  • the lead wire 14 is connected to a power source (not shown), thereby the power is supplied.
  • the cathode electrode member 12 may be connected to the lead wire 14 through a conductive cap 16.
  • FIG. 5 shows another embodiment of the invention.
  • a discharge lamp apparatus comprises a tube 21, a cathode electrode member 22 made of a semiconductor porcelain and arranged within the tube 21, and a lead wire 24 including one end wound on the cathode electrode member 22 and other end penetrating an end portion 21a of the tube 21 and projecting to outside.
  • a conical discharge surface 22a is formed on top end portion of a base 22b of the cathode electrode member 22, and a projecting end portion is made an apex 22c.
  • Numeral 23 designates a sealing support member.
  • a cathode electrode member 22 with form shown in FIG. 5 is used. However, both are different from each other in mounting structure and connection structure of a lead wire 24.
  • a base 22b of the cathode member 22 is sealed and supported through a penetrating hole provided on an end portion 21a of a tube 21, and a lead wire 24 is connected through a screw body 25.
  • the lead wire 24 is connected to the cathode electrode member 22 through a conductive cap 26.
  • FIG. 7a shows another embodiment of the invention.
  • An apparatus shown in FIG. 7a comprises a tube 31 for discharge lamp, a cathode electrode member 32 using a semiconductor porcelain and arranged within the tube 31, and a sealing support member 33 for sealing and supporting the cathode electrode member 32 within the tube 31 and near an end portion 31a of the tube 31.
  • the cathode electrode member 32 is made of the semiconductor porcelain, and is composed of one end surface formed in a circular discharge surface 32a and a base 32b.
  • the sealing support member 33 is arranged penetrating the end portion 31a of the tube 31, and a lead wire 34 is sealed and supported at the end portion 31a.
  • An end portion 34a of the lead wire 34 at inside of the tube 31 is wound on outer circumference of the base 32b, thereby the cathode electrode member 32 is supported within the tube 31 and the circular discharge surface 32a is arranged in parallel to the end portion 31a, and other end portion 34a of the lead wire 34 is projected from the end portion 31a of the tube 31 to outside.
  • a cathode electrode member 32 in FIG. 7a is used. However, both are different from each other in mounting structure and connection structure of a lead wire 34.
  • a base 32b of the cathode electrode member 32 is supported penetrating an end portion 31a of a tube 31.
  • a screw body 35 is threadably engaged with a bottom surface 32c of the cathode electrode member 32, and one end of the lead wire 34 is embedded to the screw member 35.
  • the lead wire 34 is connected through a conductive cap 36.
  • FIG. 10a shows another embodiment of the invention.
  • An apparatus in FIG. 10a comprises a discharge lamp tube (e.g., made of glass) 41, a cathode electrode member 42 using a semiconductor porcelain and arranged within the tube 41, and a sealing support member 43 for sealing and supporting the cathode electrode member 42 within the tube 41 and near an end portion 41a of the tube 41.
  • the cathode electrode member 41 is in nearly cylindrical form and provided at intermediate position with a swelling portion 42c having outer diameter slightly less than diameter of an inner wall of the tube 41.
  • a projecting base 42b in cylindrical form having outer diameter less than that of the swelling portion 42c is projected upwards from the center of an upper surface of the swelling portion 42c, and a circular discharge surface 42a is formed on an end surface of the projecting base 42b.
  • a tube fitting portion 42d having diameter less than that of the swelling portion 42c is projected downward from the center of a lower surface of the swelling portion 42c.
  • the cathode electrode member 42 is sealed within the tube 41 through the sealing layer 44 thereby the sealing member 43 is found.
  • both the tube 41 and the sealing layer 44 may be made of glass, thereby the sealing process can be facilitated and the air tightness can be improved.
  • An electrode member 45 e.g., made of silver, is formed on a projecting end portion 42e of the tube fitting portion 42d.
  • the electrode member 45 is connected to a power source (not shown), thereby the cathode electrode member 42 is energized.
  • FIG. 10c shows a modification of lead wire connection structure in FIG. 10a.
  • a screw 47 holding a lead wire 46 is threadably engaged with the projecting end portion 42e.
  • FIG. 10d shows another example of lead wire connection structure.
  • a cylindrical cap 48 holding the lead wire 46 is fitted, thereby the cathode electrode member 42 is energized.
  • the cold cathode type discharge lamp apparatus of the invention since an electron emission material is not used in the cathode electrode but the semiconductor porcelain is used, chemical reaction due to heating is not produced, thereby blackening phenomenon of the light emission tube can be prevented and the life of the discharge lamp apparatus becomes long. Also, since the semiconductor porcelain is cheap, cost of the apparatus is reduced. Further, since the semiconductor porcelain may be formed in any shape, shape of the semiconductor may be selected corresponding to the use object so as to obtain required characteristics.

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  • Discharge Lamp (AREA)
  • Vessels And Coating Films For Discharge Lamps (AREA)
EP87109938A 1986-07-15 1987-07-09 Entladungslampe mit kalter Elektrode Withdrawn EP0253316A3 (de)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
JP108598/86U 1986-07-15
JP1986108598U JPH0514455Y2 (de) 1986-07-15 1986-07-15
JP1986108597U JPH0514454Y2 (de) 1986-07-15 1986-07-15
JP1986108595U JPH0512918Y2 (de) 1986-07-15 1986-07-15
JP108595/86U 1986-07-15
JP108597/86U 1986-07-15

Publications (2)

Publication Number Publication Date
EP0253316A2 true EP0253316A2 (de) 1988-01-20
EP0253316A3 EP0253316A3 (de) 1990-03-21

Family

ID=27311264

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87109938A Withdrawn EP0253316A3 (de) 1986-07-15 1987-07-09 Entladungslampe mit kalter Elektrode

Country Status (2)

Country Link
EP (1) EP0253316A3 (de)
KR (1) KR920001844B1 (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5585694A (en) * 1990-12-04 1996-12-17 North American Philips Corporation Low pressure discharge lamp having sintered "cold cathode" discharge electrodes
US5880558A (en) * 1996-04-24 1999-03-09 Patent-Treuhand-Gesellschaft Fuer Elektrische Gluehlampen Mbh Electrode for discharge lamps
DE19802160A1 (de) * 1998-01-21 1999-07-22 Siemens Ag Lichtquelle und Verfahren zu ihrer Herstellung

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2245717A1 (de) * 1972-09-18 1974-03-28 Patra Patent Treuhand Elektrode mit einem poroesen sinterkoerper
HU179748B (en) * 1974-01-15 1982-12-28 Ferenc Puskas Cathode of a metal ceramic sintered body produced by dust metalurgy for closing discharge tube of sodium vapour lamp and process for the production thereof
US4152619A (en) * 1977-10-26 1979-05-01 Westinghouse Electric Corp. HID lamp electrode comprising barium (yttrium or rare earth metal) tungstate or molybdate

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5585694A (en) * 1990-12-04 1996-12-17 North American Philips Corporation Low pressure discharge lamp having sintered "cold cathode" discharge electrodes
US5880558A (en) * 1996-04-24 1999-03-09 Patent-Treuhand-Gesellschaft Fuer Elektrische Gluehlampen Mbh Electrode for discharge lamps
DE19802160A1 (de) * 1998-01-21 1999-07-22 Siemens Ag Lichtquelle und Verfahren zu ihrer Herstellung

Also Published As

Publication number Publication date
KR880002217A (ko) 1988-04-29
KR920001844B1 (ko) 1992-03-05
EP0253316A3 (de) 1990-03-21

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Inventor name: IWAYA, SHOUICHI

Inventor name: MASUMURA, HITOSHI

Inventor name: HAMADA, MUNEMITSU

Inventor name: ADACHI, HIROMIOHFUNA SEISAKUSHO