US3458746A - Projection lamp with a wire screen for blackening prevention - Google Patents

Projection lamp with a wire screen for blackening prevention Download PDF

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Publication number
US3458746A
US3458746A US638338A US3458746DA US3458746A US 3458746 A US3458746 A US 3458746A US 638338 A US638338 A US 638338A US 3458746D A US3458746D A US 3458746DA US 3458746 A US3458746 A US 3458746A
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US
United States
Prior art keywords
filament
lamp
mirror
screen
wire
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
US638338A
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English (en)
Inventor
Horst Horster
Jan Christiaan Pennekamp
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.)
US Philips Corp
Original Assignee
US 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 filed Critical US Philips Corp
Application granted granted Critical
Publication of US3458746A publication Critical patent/US3458746A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01K—ELECTRIC INCANDESCENT LAMPS
    • H01K1/00—Details
    • H01K1/26—Screens; Filters
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01K—ELECTRIC INCANDESCENT LAMPS
    • H01K7/00—Lamps for purposes other than general lighting
    • H01K7/02—Lamps for purposes other than general lighting for producing a narrow beam of light; for approximating a point-like source of light, e.g. for searchlight, for cinematographic projector

Definitions

  • This invention relates to a projection lamp having an elliptic condenser mirror, a filament located in the area of the focus of the mirror and a screen substantially surrounding the filament for the purpose of reducing the blackening on the inside walls of the lamp.
  • the screen is formed of a plurality of spaced wire loops which are supported by at least one stay wire mounted on a currentsupply wire.
  • the present invention relates to the above combination which is characterized in that a screen surrounding the filament and consisting of wire is arranged in the bulb.
  • the screen elements are disposed between the filament and the condenser mirror and also between the filament and the film gate or transparency to be illuminated. The presence of these screen elements at these areas does not give rise to a disturbing shadow effect.
  • one is able to achieve not only a very uniform illumination of the film gate or of the transparency, but also a greater light output of the lamp by reducing the degree of blackening of the lamp bulb.
  • An advantageous embodiment of the combination in accordance with the invention is characterized in that the screen has substantially parallel extending wire loops secured to one or more stay wires, and the shape of these wire loops is so adapted to that of the filament that the distance from a wire loop to the adjacent part of the filament is less than 5 mm.
  • the degree of blackening of the lamp bulb is considerably reduced by this step.
  • a suitable lamp construction is obtained if the stay wires of the screen are secured to the current-supply wires of the filament with the interposition of thermally insulating bodies such as glass beads.
  • the combination according to the invention may be constituted by a projection lamp and a condenser mirror structurally separated therefrom and arranged outside said lamp, it is recommendable according to a further embodiment of the invention that the projection lamp intended to be used in the said combination is constructed so that the elliptic condenser mirror forms part of the lamp,
  • the mirror may be arranged inside the lamp bulb as a self-supporting structural part or, what is generally simpler, it may be provided on the wall of the bulb, for which purpose the part of the bulb wall must have the required elliptic shape.
  • the invention is of particular advantage if the elliptic condenser mirror applied to the bulb is a so-called mirror.
  • a cold-light mirror has the advantage that the light rays it collects are reflected in the prescribed direction and that the collected heat is conducted to the outside.
  • Such a cold-light mirror which is generally called an interference mirror, loses its favourable properties, however, if evaporated material of the filament is deposited on its mirror surface. As set out hereinbefore, this disadvantage is strongly mitigated by the presence of the screen around the filament.
  • This embodiment is a projection lamp the bulb of which is partly mirror-coated.
  • FIG. 1 shows this lamp diagrammatically and partly in sectional view.
  • FIG. 2 is a perspective view of the filament with part of its terminal wires and the wire grating of the lamp, which construction is shown partly in exploded view for the sake of clarity.
  • the lamp shown has a cap 1 and a glass bulb 2 having an ellipsoidal wall portion 3-4-3 and a spherical wall portion 3-5-5-3. A focus of the ellipsoid and the centre point of the spherical portion coincide at the point F.
  • the ellopsoidal portion 3-4-3 is entirely mirror-coated and the spherical portion 3-5-5-3 is partly mirrorcoatedthe gate 5-5 being left uncovered.
  • the mirrorcoating 15 of portion 3-4-3 may be a so-called cold-light mirror-coating.
  • the flattened filament 6 lies in the proximity of the focusing point P and is secured by its ends 7 to the terminal wires 8 which are provided in the pinch 9 of a stem tube 10.
  • the wire screen 11 of the lamp consists of a plurality of flattened wire loops 12 and of two stay wires 13. The dimensions and shape of the screen are such and the screen is secured with the interposition of insulating glass beads 14 to the terminal wires 8 so, that the wire loops 12 surround the filament and the distance between a screen-wire loop and the adjacent part of the filament is smaller than 5 mm.
  • the degree of blackening of the lamp bulb may be very low so that the decrease in light output of the lamp during its life can be strongly counteracted.
  • a projection lamp including an elliptical condenser mirror, at filament located in an area of the focus of the mirror, and current-supply wires supporting the filament, the improvement in combination therewith, comprising at least one stay wire extending from a currentsupply wire, and a screen supported by said stay wire and formed of spaced wire loops which are positioned generally parallel to each other, substantially surround the filament, and are spaced less than 5 mm. from the filament.
  • a lamp as defined in claim 1 further comprising a thermal insulating element interconnecting each stay wire with a corresponding current-supply wire.
  • a projection lamp as claimed in claim 1 further comprising a bulb part with said elliptical condenser mirror forming a part thereof.
  • a projection lamp including an elliptical condenser mirror, a filament located in an area of the focus of the mirror, and current-supply wires supporting the filament, the improvement in combination therewith, comprising at least one stay wire extending from a current-supply wire, and a screen supported by said stay wire and formed of a plurality of spaced generally U-shaped wire elements one end of each element being secured to said stay wire.

Landscapes

  • Optical Elements Other Than Lenses (AREA)
  • Non-Portable Lighting Devices Or Systems Thereof (AREA)
  • Projection Apparatus (AREA)
US638338A 1966-06-04 1967-05-15 Projection lamp with a wire screen for blackening prevention Expired - Lifetime US3458746A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL6607798A NL6607798A (en, 2012) 1966-06-04 1966-06-04

Publications (1)

Publication Number Publication Date
US3458746A true US3458746A (en) 1969-07-29

Family

ID=19796796

Family Applications (1)

Application Number Title Priority Date Filing Date
US638338A Expired - Lifetime US3458746A (en) 1966-06-04 1967-05-15 Projection lamp with a wire screen for blackening prevention

Country Status (5)

Country Link
US (1) US3458746A (en, 2012)
DE (1) DE1572759A1 (en, 2012)
ES (1) ES341298A1 (en, 2012)
GB (1) GB1184704A (en, 2012)
NL (1) NL6607798A (en, 2012)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4297611A (en) * 1979-10-02 1981-10-27 Wagner Electric Corporation Control of tungsten filament erosion in a halogen lamp
WO2005010923A3 (en) * 2003-07-28 2005-07-28 Koninkl Philips Electronics Nv Electric lamp

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT355200B (de) * 1978-01-23 1980-02-25 Espe Pharm Praep Bestrahlungsgeraet zum aushaerten von durch strahlung haertbaren massen

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2232816A (en) * 1940-01-19 1941-02-25 Gen Electric Electric lamp
US2494916A (en) * 1948-02-21 1950-01-17 Gen Electric Electric lamp with blackening collector
US3025424A (en) * 1958-06-16 1962-03-13 Gen Electric Electric lamp
CA650355A (en) * 1962-10-16 Honing Wilhelm Electric incandescent lamp
US3174067A (en) * 1960-07-21 1965-03-16 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Construction for projection lamps eliminating undesired infrared radiation

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA650355A (en) * 1962-10-16 Honing Wilhelm Electric incandescent lamp
US2232816A (en) * 1940-01-19 1941-02-25 Gen Electric Electric lamp
US2494916A (en) * 1948-02-21 1950-01-17 Gen Electric Electric lamp with blackening collector
US3025424A (en) * 1958-06-16 1962-03-13 Gen Electric Electric lamp
US3174067A (en) * 1960-07-21 1965-03-16 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Construction for projection lamps eliminating undesired infrared radiation

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4297611A (en) * 1979-10-02 1981-10-27 Wagner Electric Corporation Control of tungsten filament erosion in a halogen lamp
WO2005010923A3 (en) * 2003-07-28 2005-07-28 Koninkl Philips Electronics Nv Electric lamp
US20060186816A1 (en) * 2003-07-28 2006-08-24 Koninklijke Philips Electronics N.V. Electric lamp
JP2007516571A (ja) * 2003-07-28 2007-06-21 コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ 電球

Also Published As

Publication number Publication date
ES341298A1 (es) 1968-10-16
NL6607798A (en, 2012) 1967-12-05
GB1184704A (en) 1970-03-18
DE1572759A1 (de) 1970-02-12

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