Nokia Mobile Phones Limited

Nanocomp Oy Ltd

Nokia Corporation

Nanocomp Ltd

Markku Kuittinen

Marko Parikka

Jari Turunen

Pasi Laakkonen

An arrangement () for coupling light into a plate-like light guide () having two surfaces () on opposite sides of the light guide comprises an in-coupling diffraction grating () for diffracting an external light beam () incident on said in-coupling diffraction grating into the light guide in a direction enabling the in-coupled light beam to propagate within the light guide via total internal reflections at the light guide surfaces (). According to the present invention, the arrangement further comprises a deflection member () arranged to deflect the beam () initially diffracted by the in-coupling diffraction grating (), before it hits the in-coupling diffraction grating again, out of the path determined by the in-coupling diffraction grating in order to reduce out-coupling of the already in-coupled light through the in-coupling diffraction grating.

Arrangement and a method for coupling light into a plate-like light guide

An arrangement () for coupling light into a plate-like guide () having two surfaces () on opposite sides of the light guide comprises an in-coupling diffraction grating () for diffracting an external light beam () incident on said in-coupling diffraction grating into the light guide in a direction enabling the in-coupled light beam to propagate within the light guide via total internal reflections at the light guide surfaces (). According to the present invention, the arrangement further comprises a deflection member () arranged to deflect the beam () initially diffracted by the in-coupling diffraction grating (), before it hits the in-coupling diffraction grating again, out of the path determined by the in-coupling diffraction grating in order to reduce out-coupling of the already in-coupled light through the in-coupling diffraction grating.

A light pipe includes a light input end and a diffractive structure. The diffractive structure includes elongated formations having diffractive properties for coupling light out from the light pipe to provide backlighting of a flat-panel display. The elongated formations are curved, the curvature being dependent on the location of a light source at the light input end.

Backlighting light pipe for illuminating a flat-panel display

A light pipe includes a surface provided with a pattern that has diffractive properties, where the pattern has uniform, mutually different areas on the surface such that some of the areas are configured to distribute light from a light input end of the light pipe to form macroscopically uniform distribution of light and some other areas are configured to couple light out from the light pipe in order to produce lighting, and where the relative proportion of surface covered by areas configured to distribute light is arranged to decrease in relation to increase of distance from the light input end.

The invention relates to a new light pipe () for providing backlighting () of a flat-panel display () by means of at least one light source so that the light pipe has at least one surface which comprises patterns. The patterns have diffraction properties for conducting the light in the direction of the display, and the patterns comprise uniform, mutually different areas having a certain distribution on the surface of the light pipe. The local outcoupling efficiency of the light pipe depends on the characteristic properties of the patterns, which are dependent on the distance to the light source or its wavelength.

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Joensuu, Finland

Markku Kuittinen