Backlighting device for an optical display unit

Abstract

Backlighting Device for an Optical Display Unit. The backlighting device has a transparent cover plate (2) and at least one rod-shaped optical waveguide (1) arranged along a lateral outer edge (2a) of the cover plate (2) and capable of receiving light radiation from a front face. The rod-shaped optical waveguide(s) (1) are reflective to coupled light on their outer surfaces, except for a surface area in contact with the cover plate (2) and an opposing surface area. Structural decoupling elements (4) are present on the opposing surface area to direct the light guided by the rod-shaped optical waveguide (1) into the cover plate (2) for backlighting the optical display unit into the cover plate (2). Figure for the abstract: Fig. 3

Description

Title of the invention: Backlighting device for an optical display unit

[0001] The invention relates to a backlighting device for an optical display unit, which can be used in particular on a wide variety of electronic devices. For example, it can be used for a display unit in the form of a screen or monitor, also on mobile telecommunications devices, computers, measuring instruments or control elements for a wide variety of devices and machines, for backlighting.

[0002] For example, computer screens or other electronic devices are generally backlit using artificial light sources such as LEDs (light-emitting diodes) or CFLs (compact fluorescent lamps).

[0003] In cases where these light sources known for backlighting an optical display unit are not physiologically usable for certain people or if, for other reasons, a light of particular spectral composition must be used for an optical display unit, this is not possible so far, at least in a relatively simple way, and is not provided for in current systems.

[0004] A portion of the population has problems with artificial light and is therefore excluded from digital life, which largely takes place on artificially lit screens. For the average person as well, artificial light is psychologically and physiologically harmful, so there is also an advantage for ordinary consumers to be able to, for example, use natural sunlight for lighting.

[0005] If light with different spectra and / or from different light sources is to be used for backlighting optical display elements, the effort required is quite significant. It is then necessary to use an increased number of suitable light-emitting elements and to emit them homogeneously over the display surface.

[0006] The objective of the invention is therefore to indicate possibilities for obtaining a simple and flexible possibility of backlighting optical display units, of simple structure and not requiring significant additional space, and offering the possibility of obtaining illumination, among other things, with natural sunlight.

[0007] According to the invention, this problem is solved by a backlighting device for an optical display unit with a light-transparent cover plate and at least one rod-shaped optical waveguide, which is arranged along a lateral outer edge of the cover plate, in which light radiation can be coupled in the rod-shaped optical waveguide(s) from a front face of the respective rod-shaped optical waveguide and the rod-shaped optical waveguide(s) is / are reflective, for the coupled light, on external surfaces, except for a surface area that is in contact with the cover plate and a surface area that is disposed opposite the surface area that is in contact with the cover plate, and in which structural decoupling elements are present on the surface area opposite the surface area of ​​the respective rod-shaped optical waveguide that is in contact with the cover plate, the structural decoupling elements being made to direct the light, which is guided by the respective rod-shaped optical waveguide, into the cover plate in a distributed manner along the respective outer edge of the cover plate,for the backlighting of the optical display unit, in the cover plate.

[0008] Advantageous configurations and improvements: the device includes one or more of the following optional features:

[0009] - the device is adapted to couple sunlight in a waveguide respective rod-shaped optics;

[0010] - light-emitting elements are arranged at regular intervals on the outer side of a respective rod-shaped optical waveguide on which structural decoupling elements are arranged, for additional lighting, the emitted light of which is directed into the cover plate through the respective rod-shaped optical waveguide;

[0011] - structural decoupling elements are present in the form of bumps, of hollow, structured coatings and / or a combination thereof on or in the surface area of ​​the respective rod-shaped optical waveguide which is arranged opposite the surface area which is in contact with the cover plate;

[0012] - the various light-emitting elements for additional backlighting are arranged along the length of the respective rod-shaped optical waveguide at positions that are located between structural decoupling elements arranged side by side;

[0013] - light-emitting elements are arranged on the rear face of the plate cover for additional backlighting, which is positioned opposite the side from which a visual observation of a display is made;

[0014] - the rod-shaped optical waveguide(s) has / have a length which corresponds to at least 80% of the length of the respective lateral outer edge of the cover plate on which the respective rod-shaped optical waveguide is arranged;

[0015] - light can be coupled respectively in an optical waveguide in rod-shaped by means of at least one optical fiber;

[0016] - an optical element modifying the direction of radiation of the coupled light in the rod-shaped optical waveguide and / or forming the radiation is disposed on a front face on which the light can be coupled in the respective rod-shaped optical waveguide;

[0017] - the device is disposed on one side of an optical display unit which is disposed at the opposite side from what an observer can see.

[0018] Light is hereinafter understood to mean electromagnetic radiation whose wavelengths belong to the spectrum of visible light and near-infrared light.

[0019] An optical display unit is generally a plate-shaped element whose transparency can be influenced pixel by pixel by light, onto which a person can direct their gaze and visually perceive a display or image. The plate-shaped element may be provided with additional colored filter arrays. The display or image in question is generally generated by elements (e.g., in LCD or TFT screens). Light passing through these transparent or light-absorbing elements in a controllable manner appears as a visible view from the outside for a wide variety of visually recognizable displays.

[0020] The backlighting of such display units can be obtained by a surface light source which is composed of a transparent cover plate which is provided with diffusion structures on the rear face, in which the light from at least one light source (such as an LED) can be laterally coupled.

[0021] According to the invention, at least one rod-shaped optical waveguide is arranged along a lateral outer edge of the transparent cover plate. For better and more uniform illumination of the display unit, it is advantageous for rod-shaped optical waveguides to be arranged on edges facing opposite sides of a cover plate, for example, a polygonal one.

[0022] A cover plate and one or more rod-shaped optical waveguides should preferably be made of the same transparent material, such as glass or an optically transparent plastic. If the cover plate and the rod-shaped optical waveguides are made of different materials, their optical refractive indices should differ by no more than 20%.

[0023] Light radiation can be coupled in the rod-shaped optical waveguide(s), for example via at least one optical fiber, from a front face of the respective rod-shaped optical waveguide. The light guided by the optical fiber(s) may have been emitted by a radiation source appropriate and coupled in the optical fiber(s). Light can also be coupled directly into a rod-shaped optical waveguide from a suitable radiation source.

[0024] It is also possible, for example, to couple sunlight, in particular by means of a solar collector, in a concentrated form into one or more optical fibers and to guide it through these fibers to a front end of a respective rod-shaped optical waveguide, in particular to extract it from the respective optical fiber and couple it into the rod-shaped optical waveguide at least on one of its front faces. It is also possible to couple light emitted by an artificial light source into one or more optical fibers and to guide it to a rod-shaped optical waveguide or to couple it directly into a rod-shaped optical waveguide from a corresponding radiation source.

[0025] The light from an artificial radiation source can be, for example, electromagnetic radiation from a part of the wavelength spectrum of visible light, so that, for example, backlighting of an optical display unit with a corresponding color is possible.

[0026] The rod-shaped optical waveguide(s) can be reflective for coupled light on their external surfaces, except for the surface area in contact with the cover plate and an external surface area opposite the surface area in contact with the cover plate. Thus, the coupled light can be guided through the entire rod-shaped optical waveguide, at least partially, using total internal reflection.

[0027] Due to the presence of structural decoupling elements on the surface area(s) which is / are arranged opposite the surface area of ​​the respective rod-shaped optical waveguide which is in contact with the cover plate, the light guided by the rod-shaped optical waveguide can escape and be directed into the cover plate along the outer edge to illuminate the optical display unit by the action of the structural decoupling elements.

[0028] The structural decoupling elements are made in such a way that the light rays which are guided by the respective rod-shaped optical waveguide are reflected or diffused in such a way that these light rays are directed towards the cover plate, so that they can penetrate the cover plate for the purpose of lighting through the surface of the outer edge which is in contact with the rod-shaped optical waveguide.

[0029] It is also advantageous to couple light in a rod-shaped waveguide, particularly optical fibers, from opposite front faces. This allows for uniform lighting across the entire surface of the display unit, especially when the edges of the cover plates are long.

[0030] In one embodiment of the invention, light-emitting elements may be arranged at regular intervals on the outer side of a respective rod-shaped optical waveguide on which structural decoupling elements are arranged, for additional backlighting, the emitted light of which can be directed into the cover plate by the respective rod-shaped optical waveguide. This makes it possible, for example, to obtain backlighting when there is no natural sunlight that can be coupled into a rod-shaped optical waveguide.

[0031] Changing the lighting of an optical display unit with different colours is also possible by directing a mixture of different wavelengths of light or different wavelengths of light radiation sequentially into a cover plate.

[0032] Structural decoupling elements may be present in the form of bumps, hollows, structured coatings and / or combinations thereof on or in the surface of the respective rod-shaped optical waveguide, which is disposed opposite the surface area that is in contact with the cover plate.

[0033] The various light-emitting elements for additional backlighting should advantageously be arranged along the length of the respective rod-shaped optical waveguide (at positions located between adjacent structural decoupling elements). In this way, the light emitted by these elements can be directed, at least without obstruction, from the respective light-emitting elements into the cover plate. It is also possible to obtain improved uniform backlighting over the entire surface of a display unit.

[0034] Light-emitting elements may also be present, alone or in addition, on the rear face of a cover plate, preferably in a regular arrangement, as is already most often the case. They may form a regular arrangement on this face for additional backlighting.

[0035] One or more rod-shaped optical waveguides must each have a length that corresponds to at least 80%, preferably at least 90% of the length of the respective lateral edge of the cover plate on which the respective rod-shaped optical waveguide is disposed.

[0036] Rod-shaped optical waveguides can have different cross-sectional geometries, and their cross-section can, for example, be polygonal, preferably triangular or quadrangular, or even round. Only the surface area that is in contact with an outer edge of a plate of The cover plate must be formed so as to be complementary to the surface of the respective outer edge. If the surface of an outer edge is flat and smooth, the corresponding surface area of ​​the rod-shaped optical waveguide must also be flat and smooth. When an outer edge of the respective cover plate has a convex shape, the surface area intended to be in contact with that surface must be convex in a complementary manner. In all cases, at least virtually all of the corresponding surfaces of the rod-shaped optical waveguides and the outer edge of the cover plate must be in direct contact.

[0037] The outer edges of a cover plate which are in contact with a surface area of ​​a rod-shaped optical waveguide can be made curved or convex in one or two dimensions, which results in a surface area of ​​a rod-shaped optical waveguide having to be of complementary shape.

[0038] An optical element that modifies the radiation direction of the coupled light in the rod-shaped optical waveguide must be arranged on a front face where the light can be coupled into the respective rod-shaped optical waveguide. This could be, for example, a suitably oriented reflective surface of an optical element or an optical prism. Alone or in addition, a beam-forming optical element can also be suitably arranged and used to couple light into a rod-shaped optical waveguide.

[0039] The cover plates can also be polygonal or fully or partially curved, as can, for example, the respective display units. Curved cover plates have a partially curved outer contour or the shape of an ellipse or a circle. The rod-shaped optical waveguides must then also be curved accordingly, so that the surface areas of a respective rod-shaped optical waveguide and the surface of an outer edge of the cover plate can be brought into direct contact. A curve must have a minimum radius of 20 mm.

[0040] With this principle, light can be coupled in parallel to the existing light source in the backlighting of an optical display unit. This makes it possible, for example, to couple sunlight or light from unusual light sources and to use both types of light simultaneously for backlighting. The very slim form factor of modern displays can thus be maintained.

[0041] If, for example, natural sunlight is used for backlighting a display unit, the additional simultaneous lighting with an existing LED source can also be used to maintain constant brightness (darkening by clouds and variations in brightness during the day).

[0042] The existing problem of sensitivity to artificial light affects only a minority of the population and was therefore not a central focus of the development work. Nevertheless, the invention can contribute to ensuring that electronic devices can be used without problems by people sensitive to artificial light.

[0043] The minority of the population who have problems with artificial light and are therefore excluded from digital life, which is largely conducted via artificially lit screens, can once again participate in digital society thanks to the backlighting of an optical display unit according to the invention by sunlight delivered through a rod-shaped optical waveguide and an optical fiber. Even for the average person, artificial light is psychologically and physiologically harmful, so there is also an advantage for ordinary consumers.

[0044] Other areas of application, for example with the supply of other light sources, for example by at least one optical fiber, are also conceivable using the principle of the invention.

[0045] It is possible to maintain flat shapes, as in existing optical display units, and to bring light from an alternative source (for example, the sun) through one or more multimode fibers and use it for illumination. This light can be coupled in multimode optical fibers and transmitted through them using total internal reflection.

[0046] The backlighting of an optical display unit can be largely effective by using total internal reflection in rod-shaped optical waveguides and directing the light in the direction important for illumination by means of structural decoupling elements that are arranged on or within the rod-shaped optical waveguide, or that are formed within it. These elements deflect the light towards the optical display unit and extract it from the rod-shaped optical waveguide. The structural decoupling elements must be designed so that the side facing the optical display unit can be illuminated homogeneously. To achieve this, the degree of decoupling of each structural decoupling element or their distances from each other can vary.

[0047] Other areas of application, for example with the supply of light to other light sources, in particular by optical fibers, are conceivable using the principle of the invention.

[0048] The backlighting of an optical display unit can be provided by a transparent cover plate using structural decoupling elements. In the respective cover plate, the light is preferably also guided to By means of total internal reflection, structural decoupling elements are arranged on or within the rod-shaped optical waveguide on the side opposite the optical display unit. These elements deflect the light towards the respective optical display unit and extract it from the rod-shaped optical waveguide. The structural decoupling elements must be designed so that the side facing the optical display unit is uniformly illuminated.

[0049] The light from the light-emitting elements (generally several LEDs), which can be used for additional lighting, can be coupled laterally in the transparent cover plate.

[0050] For backlighting or additional backlighting of the optical display unit, the light emitted by the light-emitting elements for illumination can pass through the rod-shaped optical waveguide virtually undisturbed.

[0051] As already mentioned, a rod-shaped optical fiber can be fed from one or two ends, which should be arranged opposite each other, each in particular by means of an optical fiber. All ends through which light does not enter or exit can be made reflective in order to increase efficiency.

[0052] For example, it is possible to use an optical waveguide with an optical fiber and an LED array on one side, or two corresponding rod-shaped optical waveguides on opposite sides of the optical display unit. This also depends on the lighting requirements and the required homogeneity.

[0053] Light extracted from a rod-shaped optical waveguide can be directly routed to an optical display unit as typical backlighting, while being distributed in a two-dimensional manner.

[0054] The light, which is also supplied by one or more optical fibers, can be distributed by a rod-shaped multimode optical fiber along one side or a respective height of the cover plate of a respective optical display unit and fed into a conventional backlighting system. Additional LED lighting can illuminate the rod-shaped multimode optical fiber without affecting its operation. Thus, a fiber-powered light source and LEDs as light-emitting elements can be used together or sequentially for backlighting, independently of each other, or even simultaneously for backlighting the optical display unit. No mechanical switching is required to change from one type of lighting to another.

[0055] The invention has the advantage of occupying only a very small space and allowing use without major modifications to existing optical display units, integrated into them. This allows the general form factor of current optical display units to be maintained.

[0056] In summary, the invention makes it possible to obtain

[0057] a) an inclusion of highly sensitive people in digital life

[0058] b) relief for health-conscious people through healthier lighting at work

[0059] c) technical applications such as infrared lighting

[0060] d) reduced electricity consumption through the direct use of solar radiation

[0061] The invention is explained in more detail below by way of non-limiting example, with reference to the drawings, on which:

[0062] [Fig.1] [Fig.1] a top view of an example of a device according to the invention;

[0063] [Fig.2a] [Fig.2a] a partial perspective representation of an example without and

[0064] [Fig.2b] [Fig.2b] a partial perspective representation of an example with additional light-emitting elements for lighting;

[0065] [Fig.3] [Fig.3] a schematic side view of an example with a display unit and

[0066] [Fig.4] [Fig.4] a schematic side view of another example with a display unit and additional light-emitting elements which are arranged under a cover plate.

[0067] Figure 1 shows a top view of an example of a device according to the invention. A transparent cover plate 2 is disposed on the side which lies behind an optical display unit 8 (not shown here).

[0068] On each of the two opposite outer edges 2a of the cover plate 2 is arranged an optical waveguide 1 in the shape of a rod, which with a surface is in direct contact with the surface of the outer edge 2a of the cover plate 2 and is transparent to light in that direction.

[0069] In the illustrated example, an optical fiber 3 is guided towards the two end faces of the rod-shaped optical waveguide 1, through which light is brought and can be coupled to a respective front face of the rod-shaped optical waveguide 1. As already mentioned in the general part of the description, sunlight, as well as light from artificial light sources, can be brought in particular by at least one optical fiber 3.

[0070] On the surface of the rod-shaped optical waveguides 1, which is arranged opposite the surface that is in contact with the cover plate 2 and through which the light is guided into the cover plate 2, structural decoupling elements 4 (also not shown here) are present, using from which the light guided by the rod-shaped optical waveguides 1 can be deflected towards the cover plate 2 and coupled to it.

[0071] On the surface on which structural decoupling elements 4 are arranged, additional light-emitting elements 5, such as LEDs, may be present in a series arrangement for additional backlighting, with the aid of which backlighting of the respective optical display unit may be obtained alone or in addition to the light which may be brought from outside by the rod-shaped optical waveguides 1 or by optical fibers 3 in the rod-shaped optical waveguides 1.

[0072] In the illustrated examples, the cover plate 2 and the cross sections of the rod-shaped optical waveguides 1 are also square.

[0073] Fig. 2a further shows how the various structural decoupling elements 4 can and should be arranged at regular intervals along the surface of an outwardly oriented rod-shaped optical waveguide 1.

[0074] Fig. 2b illustrates how additional light-emitting elements 5 are arranged in series behind the surface of the outwardly oriented rod-shaped optical waveguide 1, which can be used for additional backlighting of the optical display unit 8. The arrangement of the various light-emitting elements 5 is such that they are arranged between two adjacent structural decoupling elements 4, which ensures that at least most of the light they emit can be directed into the cover plate 2 through the rod-shaped optical waveguide 1.

[0075] Figures 2a and 2b further show that the outer front faces of the rod-shaped optical fibers 1 can be oriented at an angle, preferably 45°, to the longitudinal axis of the rod-shaped optical waveguide 1. This makes it possible to obtain improved and simplified coupling of the light from an optical fiber 3 into the rod-shaped optical waveguide 1, which has a small footprint and can therefore contribute to a reduction in size.

[0076] Figure 3 illustrates the invention from another perspective, namely from one side. Elements 6 for directing light towards a screen 8 are located under the transparent cover plate 2. The coupling intensity of these elements 6 can be varied laterally to obtain homogeneous backlighting of the display unit (screen) 8.

[0077] In the examples illustrated in Figures 3 and 4, a film 7 is present between the cover plates 2 and the display units 8 to increase the brightness of the display. A film 7 can be formed with several sheets that have structural elements oriented perpendicularly to each other in the form of micro-prisms.

[0078] On each of the two opposite outer edges 2a of the cover plate 2 is arranged a rod-shaped optical waveguide 1 such that the light which is also coupled to it by optical fibers 3 can pass through it and be coupled into the cover plate 2 at the surface which is in contact with the outer edge of the cover plate 2. In this example also, light-emitting elements 5 are present on the outwardly oriented surface of the rod-shaped optical waveguides 1, behind structural decoupling elements 4 (not shown here), for additional backlighting.

[0079] The two eyes indicated are intended to illustrate the surface that an observer looks at in order to observe the corresponding display.

[0080] Figure 4 represents another possible use of the proposed arrangement for the directly backlit display units 8. In this case, the light-emitting elements 5' usable for the additional backlighting are not arranged laterally next to the cover plate 2 and the rod-shaped optical waveguide 1, but the light-emitting elements 5' form a surface arrangement so that they pass directly through the display unit 8. In this case, if the backlight decoupling structures 6 are positioned only between the light-emitting elements 5', the coupling of the light from the optical fibers 3 can be carried out as described for Figure 3.

Claims

1.

2.

3.

4. Demands Backlighting device for an optical display unit with a light-transparent cover plate (2) and at least one rod-shaped optical waveguide (1) disposed along a lateral outer edge (2a) of the cover plate (2), wherein light radiation can be coupled into the rod-shaped optical waveguide(s) (1) from a front face of the respective rod-shaped optical waveguide(s) (1), and the rod-shaped optical waveguide(s) (1) is / are reflective, for the coupled light, on external surfaces, except for a surface area that is in contact with the cover plate (2) and a surface area that is disposed opposite the surface area that is in contact with the cover plate (2),and wherein structural decoupling elements (4) are present on the surface area opposite the surface area of ​​the respective rod-shaped optical waveguide (1) which is in contact with the cover plate (2), the structural decoupling elements (4) being made to direct the light, which is guided by the respective rod-shaped optical waveguide (1), into the cover plate (2) in a distributed manner along the respective outer edge (2a) of the cover plate (2), for backlighting the optical display unit, into the cover plate (2). A device according to claim 1, adapted for coupling sunlight into a respective rod-shaped optical waveguide (1). A device according to any one of the preceding claims, characterized in that light-emitting elements (5) are arranged at regular intervals on the outer side of a respective rod-shaped optical waveguide (1) on which structural decoupling elements (4) are arranged, for additional illumination, the emitted light of which is directed into the cover plate (2) through the respective rod-shaped optical waveguide (1). A device according to any one of the preceding claims, characterized in that structural decoupling elements (4) are present in the form of bumps, hollows, structured coatings and / or a combination thereof on or in the surface area of ​​the optical waveguide (1) in the form of a respective rod which is disposed opposite the surface area which is in contact with the cover plate (2).

5. Device according to any one of the preceding claims, characterized in that the various light-emitting elements (5) for the additional backlighting are arranged along the length of the respective rod-shaped optical waveguide (1) at positions which are located between structural decoupling elements (4) arranged side by side.

6. Device according to any one of the preceding claims, characterized in that light-emitting elements (5') are arranged on the rear face of the cover plate (2) for additional backlighting, which is arranged opposite the side from which a visual observation of a display is made.

7. Device according to any one of the preceding claims, characterized in that the rod-shaped optical waveguide(s) (1) has a length that corresponds to at least 80% of the length of the respective lateral outer edge (2a) of the cover plate (2) on which the respective rod-shaped optical waveguide (1) is disposed.

8. Device according to any one of the preceding claims, characterized in that light can be coupled respectively into a rod-shaped optical waveguide (1) by means of at least one optical fiber (3).

9. Device according to any one of the preceding claims, characterized in that an optical element modifying the radiation direction of the coupled light in the rod-shaped optical waveguide (1) and / or forming the radiation is disposed on a front face on which the light can be coupled in the respective rod-shaped optical waveguide (1).

10. Device according to any one of the preceding claims, characterized in that the device is disposed on one side of an optical display unit (8) which is disposed opposite the side that an observer can see.

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