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
  • 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
  • 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
  • G02B6/0033—Means for improving the coupling-out of light from the light guide
  • G02B6/0058—Means for improving the coupling-out of light from the light guide varying in density, size, shape or depth along the light guide
  • G02B6/006—Means for improving the coupling-out of light from the light guide varying in density, size, shape or depth along the light guide to produce indicia, symbols, texts or the like
• • 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
  • G02B6/0066—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 characterised by the light source being coupled to the light guide
  • G02B6/0068—Arrangements of plural sources, e.g. multi-colour 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
  • G02B6/0081—Mechanical or electrical aspects of the light guide and light source in the lighting device peculiar to the adaptation to planar light guides, e.g. concerning packaging
  • G02B6/0086—Positioning aspects
  • G02B6/0091—Positioning aspects of the light source relative to the light guide

Definitions

• the present invention relates to an illuminated display unit, for example a sign for displaying information, according to the preamble clause of Patent Claim 1.
• An illuminated display unit is described in EP-B-0 306 659. It consists of a light guide in the form of a plate which is connected to one or more light sources.
• the light source use is preferably made of broad-beam light- emitting diodes of 3 to 4 different wavelengths (for example blue/green, yellow and red) .
• the light is guided into the light guide through drilled or milled recesses in the light guide.
• the light source is positioned inside the distribution material.
• Highly reflective so-called mixing chambers are arranged before the light is reflected out into the light guide so as to mix the monochrome light from the light-emitting diodes to form light with a broader waveband which the eye perceives as white light.
• the edges of the light guide are coated with reflective layers which reflect the light back into the light guide until the desired angle of reflection is obtained.
• the repeated reflections contribute to the colour mixing of the light.
• the light- guide plate is arranged in front of a contrast surface, seen from that side of the display unit which is to be looked at during use. On that surface of the light-guide plate which faces the contrast surface, a display symbol
• a disadvantage of the technique described above is that it allows inadequate control over where and in which direction the light is reflected out of the light guide.
• the light scatter over a relatively large area of the light guide may therefore be very uneven.
• Fig. 1 is a diagrammatic perspective view of a display unit according to the present invention
• Fig. 2 is a diagrammatic, partially cut-off plan view of a part of the display unit according to Figure 1;
• Figs 3A and 3B are diagrammatic perspective views of two different embodiments of recesses in a light guide according to the present invention.
• Fig. 4 is a diagrammatic plan view of a light guide according to the invention showing the position of the light sources.
• Fig. 1 shows a display unit 10 according to the present invention.
• the display unit comprises a light guide 20, advantageously designed as a thin rectangular plate.
• the edges 121, 122, 123 of the light guide are coated with reflective layers.
• the light guide 20, and thus the whole display unit 10 can be made very thin, a typical value being a thickness of 12 mm.
• an information carrier 70 is arranged, through which light from the light guide 20 shines.
• the information carrier 70 may consist of a transparent or opaque sheet with varying contrast patterns, a screen- printed pattern or the like. If the light is to be coloured in part, for example in the case of representation of pictograms, a transparent or opaque coloured layer is advantageously arranged on those parts of the surface of the light guide which are to display coloured light. This layer therefore serves as a coloured filter.
• Fig. 2 shows a cross-section of a display unit 10 according to Fig. 1.
• light sources 100 are arranged along a first edge 110 of the light guide 20.
• the light sources are mounted in one or more recesses 80, 90 which are, for example, drilled or milled directly into the light guide 20, and the illumination therefore takes place laterally into the light guide.
• a number of monochrome light sources 100 are therefore arranged in a recess 80, 90, the light emitted from each of the light sources being mixed by reflection in the light guide to form light that is perceived as white by the eye of an observer. This light is then guided onward into the light guide 20.
• the surface 35 of a second side 30 of the light guide is matted, which side is defined as that side which is opposite the first side 60 of the light guide.
• This matted surface 35 makes it possible to reflect the light out at the desired place in the light guide 20 and in the desired direction from the light guide. Matting is carried out either mechanically, for example by grinding or applying a matted layer, or chemically, for example by etching.
• the angle of reflection of the light waves will be broken up sufficiently to make it possible to guide the light with the desired direction and extent.
• the result of this is that the light scatter over the surface of the entire light guide 20 can become more uniform.
• Sufficient diffusion is achieved in the matted surface 35 of the second side 30 of the light guide for a uniform white light to be displayed without diffusion in additional layers being required.
• a diffusing layer may nevertheless be applied to the light guide if necessary.
• the colour exposed is thus controlled by the wavelength or the combination of wavelengths of the monochrome light sources 100.
• the second side 30 of the light guide is then covered by a completely reflective layer 40, for example a mirror or a white-painted sheet.
• the light sources 100 preferably broad-beam light- emitting diodes which emit light of one or more different wavelengths, for example of 3 to 4 different wavelengths (for example blue/green, yellow and red), are advantageously supplied with high voltage directly from the electric mains (not shown in the figures) .
• the diodes are connected in series and are supplied with a limited current intensity. This method results in lower power consumption than the alternative method where either each diode is supplied separately, that is to say connected in parallel with the other diodes, in which case the mains voltage has to be transformed down, or the diodes are arranged in clusters which consist of series-connected diodes but the various clusters are connected in parallel to the mains voltage and this voltage has to be transformed down in this case also.
• the reflective coating of the edges 121, 122, 123 of the light guide 20 may advantageously be designed with one or more light outlets so as to illuminate objects situated close to said display unit.
• the light outlets may consist of unpainted parts of the edges 121, 122, 123 or parts where the coating has been scraped off.
• the light outlets allow a given amount of the light in the light guide 20 to leave the light guide in order to illuminate, for example, a door opening located below the display unit.
• the light source for this light is advantageously light- emitting diodes mounted in the same series connection as the diodes that illuminate the information carrier of the display unit.
• a display unit according to the invention is characterized by extremely low power consumption, the value typically lying between 0.8 and 1.5 which may be compared with conventional technology where use is made of strip lamps which have a power consumption of 15 to 20 .
• the uniformity of the light intensity measured over the entire luminous sign surface is also very good, a typical value being a ratio of 3:4 between the side located furthest away from the light sources and the side closest to the light sources.
• the unit is maintenance-free for a very long time - longer than 10 years may be anticipated.
• a display unit according to the invention moreover satisfies all the requirements in PREN 1838 that are relevant to the construction and the application.
• a double-sided display unit may be envisaged, in which therefore the reflector layer on the rear side of the single-sided sign is omitted and a layer which reflects some of the light inwards towards the light guide and also diffuses the rest of the light away from the light guide is mounted either on the same side as the matted surface of the light guide or on the opposite side of the light guide.
• An embodiment with battery backup is also possible, in which the display unit is then supplied, during battery operation, with a controlled voltage instead of controlled current intensity.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Illuminated Signs And Luminous Advertising (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=20407692

Family Applications (1)

Country Status (4)

Cited By (1)

Families Citing this family (11)

Family Cites Families (3)

• 1997
  • 1997-07-08 SE SE9702643A patent/SE512755C2/sv not_active IP Right Cessation
• 1998
  • 1998-07-08 WO PCT/SE1998/001355 patent/WO1999003086A1/en not_active Application Discontinuation
  • 1998-07-08 EP EP98934069A patent/EP1010160A1/de not_active Withdrawn
  • 1998-07-08 AU AU83672/98A patent/AU8367298A/en not_active Abandoned

Non-Patent Citations (1)

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