GB2164437A - Flat light sources - Google Patents

Flat light sources Download PDF

Info

Publication number
GB2164437A
GB2164437A GB08522278A GB8522278A GB2164437A GB 2164437 A GB2164437 A GB 2164437A GB 08522278 A GB08522278 A GB 08522278A GB 8522278 A GB8522278 A GB 8522278A GB 2164437 A GB2164437 A GB 2164437A
Authority
GB
United Kingdom
Prior art keywords
light source
light
plate
recess
flat
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.)
Granted
Application number
GB08522278A
Other versions
GB8522278D0 (en
GB2164437B (en
Inventor
Uri Gal
Jacob Golan
Martin Prester
Shlomo Berliner
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.)
Motorola Solutions Israel Ltd
Original Assignee
Motorola Israel Ltd
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 Motorola Israel Ltd filed Critical Motorola Israel Ltd
Publication of GB8522278D0 publication Critical patent/GB8522278D0/en
Publication of GB2164437A publication Critical patent/GB2164437A/en
Application granted granted Critical
Publication of GB2164437B publication Critical patent/GB2164437B/en
Expired legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J29/00—Details of, or accessories for, typewriters or selective printing mechanisms not otherwise provided for
    • B41J29/18—Mechanisms for rendering the print visible to the operator
    • B41J29/19—Mechanisms for rendering the print visible to the operator with reflectors or illuminating devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V7/00—Reflectors for light sources
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
    • G02B6/0015—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/0018—Redirecting means on the surface of the light guide
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
    • G02B6/0015—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/002—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it by shaping at least a portion of the light guide, e.g. with collimating, focussing or diverging surfaces
    • G02B6/0021—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it by shaping at least a portion of the light guide, e.g. with collimating, focussing or diverging surfaces for housing at least a part of the light source, e.g. by forming holes or recesses
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F13/00—Illuminated signs; Luminous advertising
    • G09F13/18—Edge-illuminated signs
    • G09F2013/1804—Achieving homogeneous illumination
    • G09F2013/1831—Achieving homogeneous illumination using more than one light source
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2219/00—Legends
    • H01H2219/054—Optical elements
    • H01H2219/056—Diffuser; Uneven surface
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2219/00—Legends
    • H01H2219/054—Optical elements
    • H01H2219/064—Optical isolation of switch sites

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Planar Illumination Modules (AREA)
  • Illuminated Signs And Luminous Advertising (AREA)

Abstract

There is described a flat light source in which a flat light spreading plate (4) is provided adjacent a number of light sources (2), the face of the plate adjacent the light sources having cylindrical recesses (5) with internally polished surfaces, one recess opposing each light source. In the opposing face of the plate and opposite each cylindrical recess is a respective conical recess (6) to direct transmitted light back into the plate. The light source is particularly suitable for the back illumination of keyboards. <IMAGE>

Description

SPECIFICATION Flat light source FIELD OF INVENTION This invention relates to a flat light source suitable for providing illumination of transparent keyboards, displays and complex indicator lights.
BACKGROUND ART It is known to illuminate transparent displays using incadescent light bulbs. However, such methods of illumination result in light sources which do not give adequately even illumination over a relatively wide area, have a high power consumption and a low mean time between failure.
BRIEF DESCRIPTION OF INVENTION An embodiment of the present invention seeks to provide a flat light source in which the above mentioned disadvantages are emitigated.
In accordance with a broad aspect of the present invention a flat light source comprises one or more light sources and light spreading means for spreading light received from the one or more light sources over a pre determined area.
The light spreading means may be a light transmitting plate having one face adjacent the light source(s) and, typically is an acrylic plate.
Preferably the plate includes, in its face adjacent the light source(s), a respective recess opposite each light source each recess being preferably cylindrical in shape and having polished internal surfaces.
Preferably the face of the plate opposite that adjacent the light source(s) includes one or more conical recesses for reflecting light transmitted through the plate, back into the plate.
Preferably a respective conical recess is provided opposite each of the said recesses.
In a preferred embodiment the face of the plate adjacent the light source(s) is textured and may be white painted.
BRIEF DESCRIPTION OF THE DRAWINGS An exempiary embodiment of the invention will now be described with reference to the drawings in which: Figure 1 is a schematic cross sectional view of a flat light source in accordance with the present invention, and Figure 2 is a schematic plan view of the source of Fig. 1.
DETAILED DESCRIPTION OF THE INVENTION Referring now to Fig. 1 the light source 1 comprises individual light sources 2 in the form of light-emitting diodes which are mounted on a printed circuit board 3.
Mounted above and in close proximity to the printed circuit board 3 is an acrylic plate 4 which serves both as a light carrier and scattering medium.
Located in the acrylic plate 4 and aligned with each light emitting diode 2 is a cylindrical recess 5. In the opposite surface of the plate 4 and directly opposite each recess 5 is a conical recess 6 which as will be seen shortly, acts as a reflector to direct light into the acrylic plate.
The light emitting diodes 2 are narrow angle light-emitting diodes and when illuminated by means of an elctrical current fed through the tracks of the printed circuit board 3, they project a narrow beam of light into each recess 5. The acrylic plate 4 has a surface 7 facing the printed circuit board 3 which is textured and is painted with white paint to form a back plane of the plate. Each recess 5 has internal surfaces 8 which are not painted but are highly polished.
In similar manner the internal surfaces 9 of the conical recesses 6 together with the whole of the surface of the plate 4 opposite to the face 7, are also highly polished.
The apex angle of each conical recess 6 is typically 90 degrees and the polished angled surfaces of each conical recess 6 acts to diect and spread the light which is illuminating the opposing cylindrical recess 5, into the body of the acrylic plate 4.
The acrylic plate 4 itself then acts as a uniform flat light source to provide a flat beam of light 10 for illuminating a transparent keyboard display or other indicating means.
Fig. 2, which is generally self explanatory is a plan view of the light source of Fig. 1 looking down onto the surface of the plate 4, in which is formed the conical recesses 6. As can be seen, in order to obtain a good even light source over the entire surface of the plate 4, a plurality of light-emitting diodes and associated cylindrical recesses 5 are provided.
In this particular example the plate 4 is rectangular and four light sources and light spreading recesses 5 and 6 provide a flat light source to give relatively even illumination over the whole rectangular area.
The invention has been described by way of example and modifications may be made without departing from the scope of the invention.
In particular, the precise arrangement and shape of the recesses 5 and 6 are not absolutely essential and any suitable arrangement may be provided for spreading the light emitted by the light sources 2 into the plate 4, to provide a flat light source capable of providing relatively even illumination over a relatively wide area.
In a preferred form the light source described has low energy consumption and a high mean time between failures.
1. A flat light source comprising one or
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (13)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Flat light source FIELD OF INVENTION This invention relates to a flat light source suitable for providing illumination of transparent keyboards, displays and complex indicator lights. BACKGROUND ART It is known to illuminate transparent displays using incadescent light bulbs. However, such methods of illumination result in light sources which do not give adequately even illumination over a relatively wide area, have a high power consumption and a low mean time between failure. BRIEF DESCRIPTION OF INVENTION An embodiment of the present invention seeks to provide a flat light source in which the above mentioned disadvantages are emitigated. In accordance with a broad aspect of the present invention a flat light source comprises one or more light sources and light spreading means for spreading light received from the one or more light sources over a pre determined area. The light spreading means may be a light transmitting plate having one face adjacent the light source(s) and, typically is an acrylic plate. Preferably the plate includes, in its face adjacent the light source(s), a respective recess opposite each light source each recess being preferably cylindrical in shape and having polished internal surfaces. Preferably the face of the plate opposite that adjacent the light source(s) includes one or more conical recesses for reflecting light transmitted through the plate, back into the plate. Preferably a respective conical recess is provided opposite each of the said recesses. In a preferred embodiment the face of the plate adjacent the light source(s) is textured and may be white painted. BRIEF DESCRIPTION OF THE DRAWINGS An exempiary embodiment of the invention will now be described with reference to the drawings in which: Figure 1 is a schematic cross sectional view of a flat light source in accordance with the present invention, and Figure 2 is a schematic plan view of the source of Fig. 1. DETAILED DESCRIPTION OF THE INVENTION Referring now to Fig. 1 the light source 1 comprises individual light sources 2 in the form of light-emitting diodes which are mounted on a printed circuit board 3. Mounted above and in close proximity to the printed circuit board 3 is an acrylic plate 4 which serves both as a light carrier and scattering medium. Located in the acrylic plate 4 and aligned with each light emitting diode 2 is a cylindrical recess 5. In the opposite surface of the plate 4 and directly opposite each recess 5 is a conical recess 6 which as will be seen shortly, acts as a reflector to direct light into the acrylic plate. The light emitting diodes 2 are narrow angle light-emitting diodes and when illuminated by means of an elctrical current fed through the tracks of the printed circuit board 3, they project a narrow beam of light into each recess 5. The acrylic plate 4 has a surface 7 facing the printed circuit board 3 which is textured and is painted with white paint to form a back plane of the plate. Each recess 5 has internal surfaces 8 which are not painted but are highly polished. In similar manner the internal surfaces 9 of the conical recesses 6 together with the whole of the surface of the plate 4 opposite to the face 7, are also highly polished. The apex angle of each conical recess 6 is typically 90 degrees and the polished angled surfaces of each conical recess 6 acts to diect and spread the light which is illuminating the opposing cylindrical recess 5, into the body of the acrylic plate 4. The acrylic plate 4 itself then acts as a uniform flat light source to provide a flat beam of light 10 for illuminating a transparent keyboard display or other indicating means. Fig. 2, which is generally self explanatory is a plan view of the light source of Fig. 1 looking down onto the surface of the plate 4, in which is formed the conical recesses 6. As can be seen, in order to obtain a good even light source over the entire surface of the plate 4, a plurality of light-emitting diodes and associated cylindrical recesses 5 are provided. In this particular example the plate 4 is rectangular and four light sources and light spreading recesses 5 and 6 provide a flat light source to give relatively even illumination over the whole rectangular area. The invention has been described by way of example and modifications may be made without departing from the scope of the invention. In particular, the precise arrangement and shape of the recesses 5 and 6 are not absolutely essential and any suitable arrangement may be provided for spreading the light emitted by the light sources 2 into the plate 4, to provide a flat light source capable of providing relatively even illumination over a relatively wide area. In a preferred form the light source described has low energy consumption and a high mean time between failures. CLAIMS
1. A flat light source comprising one or more light sources and light spreading means for spreading light received from the one or more light sources over a pre determined area.
2. The light source of claim 1 in which the light spreading means is a light transmitting plate having one face adjacent the light source(s).
3. The light source of claim 2 in which the plate is an acrylic plate.
4. The light source of claim 2 or 3 in which the plate includes, in its face adjacent the light source(s), a respective recess opposite each light source.
5. The light source of claim 4 in which each recess is cylindrical in shape.
6. The light source of claim 4 or 5 in which the internal surfaces of each recess are polished.
7. The light source of any one of claims 2 to 6 in which the face of the plate opposite that adjacent the light source(s) includes one or more conical recesses for reflecting light transmitted through the plate, back into the plate.
8. The light source of claims 7 and 3 in which a respective conical recess is provided opposite each of the said recesses.
9. The light source of claims 7 or 8 in which the apex angle of the or each conical recess is 90".
10. The light source of any one of claims 2 to 9 in which the face of the plate adjacent the light source(s) is textured.
11. The light source of any one of claims 2 to 10 in which the face of the plate adjacent the light source (s) in white painted.
12. The light source of any preceeding claim wherein the light source(s) are narrow angle light-emitting diodes.
13. A flat light source substantially as herein described with reference to the drawings.
GB08522278A 1984-09-15 1985-09-09 Flat light source Expired GB2164437B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB848423357A GB8423357D0 (en) 1984-09-15 1984-09-15 Flat light source

Publications (3)

Publication Number Publication Date
GB8522278D0 GB8522278D0 (en) 1985-10-16
GB2164437A true GB2164437A (en) 1986-03-19
GB2164437B GB2164437B (en) 1988-06-29

Family

ID=10566769

Family Applications (2)

Application Number Title Priority Date Filing Date
GB848423357A Pending GB8423357D0 (en) 1984-09-15 1984-09-15 Flat light source
GB08522278A Expired GB2164437B (en) 1984-09-15 1985-09-09 Flat light source

Family Applications Before (1)

Application Number Title Priority Date Filing Date
GB848423357A Pending GB8423357D0 (en) 1984-09-15 1984-09-15 Flat light source

Country Status (2)

Country Link
GB (2) GB8423357D0 (en)
IL (1) IL76292A (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1990013885A1 (en) * 1989-05-02 1990-11-15 Lydia Wustlich Vertrieb Elektronischer Bauteile Surface display for illuminating background surfaces
EP0459153A2 (en) * 1990-04-27 1991-12-04 Mitsubishi Rayon Co., Ltd Optical fiber display apparatus, fixing device for optical fiber used therein, and decorative optical fiber usable therein
DE102006009694A1 (en) * 2006-03-02 2007-09-20 Paul Heinrich Neuhorst Light has multiple LEDs as source of light, disk is provided in which multiple through-openings and LEDs are located in through-openings on common printed circuit board
EP1478954B1 (en) * 2002-02-22 2007-12-05 Lumileds Lighting B.V. Compact lighting system and display device
WO2014057395A1 (en) * 2012-10-11 2014-04-17 Koninklijke Philips N.V. Thin and efficient light guide system
DE102021131390A1 (en) 2021-11-30 2023-06-01 Ambright GmbH LIGHTING DEVICE

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1990013885A1 (en) * 1989-05-02 1990-11-15 Lydia Wustlich Vertrieb Elektronischer Bauteile Surface display for illuminating background surfaces
EP0459153A2 (en) * 1990-04-27 1991-12-04 Mitsubishi Rayon Co., Ltd Optical fiber display apparatus, fixing device for optical fiber used therein, and decorative optical fiber usable therein
EP0459153A3 (en) * 1990-04-27 1992-12-02 Mitsubishi Rayon Co., Ltd Optical fiber display apparatus, fixing device for optical fiber used therein, and decorative optical fiber usable therein
EP1478954B1 (en) * 2002-02-22 2007-12-05 Lumileds Lighting B.V. Compact lighting system and display device
DE102006009694A1 (en) * 2006-03-02 2007-09-20 Paul Heinrich Neuhorst Light has multiple LEDs as source of light, disk is provided in which multiple through-openings and LEDs are located in through-openings on common printed circuit board
WO2014057395A1 (en) * 2012-10-11 2014-04-17 Koninklijke Philips N.V. Thin and efficient light guide system
DE102021131390A1 (en) 2021-11-30 2023-06-01 Ambright GmbH LIGHTING DEVICE

Also Published As

Publication number Publication date
GB8522278D0 (en) 1985-10-16
GB2164437B (en) 1988-06-29
GB8423357D0 (en) 1984-11-07
IL76292A (en) 1989-01-31

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PCNP Patent ceased through non-payment of renewal fee