GB1253237A - - Google Patents

Info

Publication number
GB1253237A
GB1253237A GB1253237DA GB1253237A GB 1253237 A GB1253237 A GB 1253237A GB 1253237D A GB1253237D A GB 1253237DA GB 1253237 A GB1253237 A GB 1253237A
Authority
GB
United Kingdom
Prior art keywords
shield
louvres
transparent
nov
matrix
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
Application number
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 filed Critical
Publication of GB1253237A publication Critical patent/GB1253237A/en
Expired legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/132—Overhead projectors, i.e. capable of projecting hand-writing or drawing during action

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Overhead Projectors And Projection Screens (AREA)
  • Projection Apparatus (AREA)
  • Optical Elements Other Than Lenses (AREA)

Abstract

1,253,237. Overhead projections; light shields. MINNESOTA MINING & MFG; CO. Nov. 13, 1968 [Nov.14, 1967; March 11, 1968(2)], No.53893/68. Headings G2A and G2J. In an overhead projector a glare shield 22 is placed between the transparency support stage 15 and the Fresnel condensing lens 19, the shield comprising a transparent matrix of closely spaced opaque thin parallel louvres 24, 25 having an aspect ratio of between 2 and 4. The louvres may be perpendicular to or inclined to stage 15, and the panel comprising said matrix is rotated about a vertical axis to give shielding in a selected direction. Superposed transparent plastics films, each with one opaque black face, are consolidated into a solid block, and shield panels are made by taking slices from the block and mounting them between glass or plastics sheets. Another form of shield comprises intermeshing grooved transparent plates, the glare light rays being totally reflected. Again, the louvres may consist of parallel inclined grooves in a transparent sheet, the grooves being filled with non- reflective particles. The preformed shield is a flexible sheet which takes a flat bottomed trough shape within a frame. Again, the louvres may be formed as concentric rings.
GB1253237D 1967-11-14 1968-11-13 Expired GB1253237A (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US68295167A 1967-11-14 1967-11-14
US71226268A 1968-03-11 1968-03-11
US71226368A 1968-03-11 1968-03-11

Publications (1)

Publication Number Publication Date
GB1253237A true GB1253237A (en) 1971-11-10

Family

ID=27418406

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1253237D Expired GB1253237A (en) 1967-11-14 1968-11-13

Country Status (7)

Country Link
JP (1) JPS5126808B1 (en)
CH (1) CH494975A (en)
DE (2) DE1808532B2 (en)
FR (1) FR1591751A (en)
GB (1) GB1253237A (en)
NL (1) NL164396B (en)
SE (1) SE347581B (en)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2914682C3 (en) * 1979-04-11 1982-05-13 Schott Glaswerke, 6500 Mainz Process for the production of a glass plate acting as a light screen and a glass plate produced according to this process
DE2937433C2 (en) * 1979-09-15 1981-08-06 Standard Elektrik Lorenz Ag, 7000 Stuttgart Exposure arrangement
DE3127247A1 (en) * 1981-07-10 1983-01-20 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Process for producing a louvre filter and device for carrying out the process
DE3414848A1 (en) * 1983-04-26 1984-11-22 Barmag Barmer Maschinenfabrik Ag, 5630 Remscheid Light-transmitting composite body
WO2021198888A1 (en) 2020-03-31 2021-10-07 Pi Industries Ltd. An improved enzyme catalyzed carboxylation reaction

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3255665A (en) * 1964-05-21 1966-06-14 Minnesota Mining & Mfg Article of manufacture for controlling light transmittance
US3340765A (en) * 1964-07-27 1967-09-12 Bell Telephone Labor Inc Projection system

Also Published As

Publication number Publication date
DE1808532B2 (en) 1972-01-27
SE347581B (en) 1972-08-07
CH494975A (en) 1970-08-15
DE1817823A1 (en) 1972-03-09
DE1817823B2 (en) 1974-01-03
FR1591751A (en) 1970-05-04
JPS5126808B1 (en) 1976-08-09
NL164396B (en) 1980-07-15
DE1817823C3 (en) 1974-07-25
NL6815702A (en) 1969-05-19
DE1808532A1 (en) 1969-08-07

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Legal Events

Date Code Title Description
PS Patent sealed
PCNP Patent ceased through non-payment of renewal fee