GB1520471A - Low-glare overhead projector - Google Patents
Low-glare overhead projectorInfo
- 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
Links
- 238000003491 array Methods 0.000 abstract 3
- 230000004313 glare Effects 0.000 abstract 1
- 239000011521 glass Substances 0.000 abstract 1
- 238000005065 mining Methods 0.000 abstract 1
- 229920003023 plastic Polymers 0.000 abstract 1
- 239000004033 plastic Substances 0.000 abstract 1
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).
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)
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)
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 |
-
1975
- 1975-08-11 SE SE7508976A patent/SE418423B/en not_active IP Right Cessation
- 1975-08-20 FI FI752349A patent/FI63118C/en not_active IP Right Cessation
- 1975-08-20 IT IT51014/75A patent/IT1041287B/en active
- 1975-08-20 GB GB34651/75A patent/GB1520471A/en not_active Expired
- 1975-08-20 AU AU84117/75A patent/AU475642B2/en not_active Expired
- 1975-08-20 FR FR7525722A patent/FR2282656A1/en active Granted
- 1975-08-20 DE DE2537547A patent/DE2537547C3/en not_active Expired
- 1975-08-20 BR BR7505320*A patent/BR7505320A/en unknown
- 1975-08-20 JP JP10109575A patent/JPS5343825B2/ja not_active Expired
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) |