GB1520471A - Low-glare overhead projector - Google Patents

Low-glare overhead projector

Info

Publication number
GB1520471A
GB1520471A GB34651/75A GB3465175A GB1520471A GB 1520471 A GB1520471 A GB 1520471A GB 34651/75 A GB34651/75 A GB 34651/75A GB 3465175 A GB3465175 A GB 3465175A GB 1520471 A GB1520471 A GB 1520471A
Authority
GB
United Kingdom
Prior art keywords
degrees
arrays
show
lens arrangement
relatively displaced
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
GB34651/75A
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.)
3M Co
Original Assignee
Minnesota Mining and Manufacturing Co
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 US05/554,417 external-priority patent/US3982822A/en
Application filed by Minnesota Mining and Manufacturing Co filed Critical Minnesota Mining and Manufacturing Co
Publication of GB1520471A publication Critical patent/GB1520471A/en
Expired legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
    • B32B3/26—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer
    • B32B3/30—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer characterised by a layer formed with recesses or projections, e.g. hollows, grooves, protuberances, ribs
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B19/00—Condensers, e.g. light collectors or similar non-imaging optics
    • G02B19/0004—Condensers, e.g. light collectors or similar non-imaging optics characterised by the optical means employed
    • G02B19/0009—Condensers, e.g. light collectors or similar non-imaging optics characterised by the optical means employed having refractive surfaces only
    • G02B19/0014—Condensers, e.g. light collectors or similar non-imaging optics characterised by the optical means employed having refractive surfaces only at least one surface having optical power
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B19/00—Condensers, e.g. light collectors or similar non-imaging optics
    • G02B19/0033—Condensers, e.g. light collectors or similar non-imaging optics characterised by the use
    • G02B19/0047—Condensers, e.g. light collectors or similar non-imaging optics characterised by the use for use with a light source
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G02B3/02—Simple or compound lenses with non-spherical faces
    • G02B3/08—Simple or compound lenses with non-spherical faces with discontinuous faces, e.g. Fresnel lens
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/40—Properties of the layers or laminate having particular optical properties
    • B32B2307/418—Refractive
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2551/00—Optical elements

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Overhead Projectors And Projection Screens (AREA)
  • Projection Apparatus (AREA)
  • Lenses (AREA)
  • Liquid Crystal (AREA)

Abstract

1520471 Overhead projectors MINNESOTA MINING & Mfg CO 20 Aug 1975 [21 Aug 1974 3 March 1975] 34651/75 HeadingG2J [Also in Division B5] An overhead projector has a light source, a lens arrangement 100, 101, 102, a support 99 for a transparency to be projected and a projection head; the lens arrangement comprising at least two surfaces 100, 101, 102 each formed with an array of straight, parallel grooves and ridges; the grooves and ridges of one array being inclined to those of the other(s). The purpose of this lens arrangement is to reduce glare. Fig. 12 shows a triplet of arrays angled at 60 degrees to each other, Figs. 13, 14 (not shown) show two such triplets relatively displaced by 10 degrees, Figs. 4 to 8 (not shown) show a pair of arrays at right angles; Figs. 9, 10, 16 (not shown) show two such pairs, relatively displaced by 30 degrees; and Fig. 15 (not shown) shows three such pairs relatively displaced by 10 to 15 degrees. Typically the arrays are plastics and the transparency support is glass and is laminated thereto (see Division B5).
GB34651/75A 1974-08-21 1975-08-20 Low-glare overhead projector Expired GB1520471A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US49913874A 1974-08-21 1974-08-21
US05/554,417 US3982822A (en) 1975-03-03 1975-03-03 Composite Fresnel lens assembly

Publications (1)

Publication Number Publication Date
GB1520471A true GB1520471A (en) 1978-08-09

Family

ID=27053045

Family Applications (1)

Application Number Title Priority Date Filing Date
GB34651/75A Expired GB1520471A (en) 1974-08-21 1975-08-20 Low-glare overhead projector

Country Status (9)

Country Link
JP (1) JPS5343825B2 (en)
AU (1) AU475642B2 (en)
BR (1) BR7505320A (en)
DE (1) DE2537547C3 (en)
FI (1) FI63118C (en)
FR (1) FR2282656A1 (en)
GB (1) GB1520471A (en)
IT (1) IT1041287B (en)
SE (1) SE418423B (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2472197A1 (en) * 1979-12-18 1981-06-26 Cintra Daniel Fresnel lens for TV screen - has grooves with sidewall being functions of groove and lens radii
DE4207940C2 (en) * 1992-03-12 1995-08-17 Gerd Kueppersbusch Labeling device
US5296882A (en) * 1992-12-21 1994-03-22 Minnesota Mining And Manufacturing Company Overhead projector with catadioptric fresnel lens
JP2957910B2 (en) * 1994-07-08 1999-10-06 大日本スクリーン製造株式会社 Lighting equipment

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3511563A (en) * 1967-11-14 1970-05-12 Minnesota Mining & Mfg Projector
DE2317830C3 (en) * 1973-04-09 1980-06-19 Ernst Leitz Wetzlar Gmbh, 6300 Lahn- Wetzlar Transmitted light writing projector

Also Published As

Publication number Publication date
FI752349A (en) 1976-02-22
DE2537547A1 (en) 1976-03-11
SE7508976L (en) 1976-02-23
FI63118B (en) 1982-12-31
AU475642B2 (en) 1976-08-26
AU8411775A (en) 1976-08-26
FI63118C (en) 1983-04-11
JPS5343825B2 (en) 1978-11-22
DE2537547C3 (en) 1981-05-27
SE418423B (en) 1981-05-25
BR7505320A (en) 1976-08-03
IT1041287B (en) 1980-01-10
DE2537547B2 (en) 1980-10-02
FR2282656A1 (en) 1976-03-19
JPS5152827A (en) 1976-05-10
FR2282656B1 (en) 1978-04-07

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Legal Events

Date Code Title Description
PS Patent sealed [section 19, patents act 1949]
PCNP Patent ceased through non-payment of renewal fee
732 Registration of transactions, instruments or events in the register (sect. 32/1977)