Pointer cap illumination

An illuminated pointer cap for an vehicle instrument panel outputs different colors from a white light source by directing the white light through different color filters. The white light is transmitted through a light-conductive substrate and reflected to the color filters by triangular-shaped undercuts formed in one side of the substrate that is opposite the color filters.

BACKGROUND

Many vehicle instrument clusters use multi-colored displays for a variety of reasons. Providing multiple colors on an instrument cluster, however, requires corresponding colored light sources. An instrument panel display that provides multiple different colors but using a single white light source would be an improvement over the prior art.

DETAILED DESCRIPTION

FIG. 1is a perspective view of a multi-color display100for an instrument panel. InFIG. 1, the device is a tachometer. The display device100comprises a circuit board1, which supports a single white light emitting diode (LED) above which is a unitary light-transmissive acrylic “substrate” that is comprised of a “post portion”5and a “planar portion”7.

The display has a multi-color light output from the top surface11of the planar portion7, the planar portion7being supported by and attached to a post portion5. The top surface11has a beveled peripheral edge13, the outside corner of which is identified by reference numeral9.

FIG. 2is a top view of the device shown inFIG. 1. The planar portion7has a top surface11and an opposing bottom surface12. The post portion5and the planar portion7are a unitary structure made of a light-transmissive acrylic or a polycarbonate. As used herein, the post portion5and the planar portion7are considered to be a light-transmissive acrylic or polycarbonate substrate, which is optically coupled to the white light source2, which is attached to the circuit board1.

FIG. 3is a sectional view of the device shown inFIG. 1andFIG. 2taken through section lines A-A. The post portion5is essentially a column, i.e. it is considered herein to be substantially columnar. It has a first end6directly above the white light source2. An opposing second end8has the beveled outside corner9and is a contiguous or unitary structure with the planar portion7. Since the columnar post portion5and the planar portion7are a unitary structure and made from a light-transmissive acrylic, light that is emitted from the light source2is coupled into the substantially planar first end of the post portion5, travels upwardly through the post portion5and is reflected by the beveled outside corner sideways or laterally into the planar portion7.

Still referring toFIG. 3, the planar portion7is provided with an undercut15which is essentially a triangular-shaped cut formed into the lower or bottom surface12of the planar portion7. The undercut15has a hypotenuse17which extends into the planar portion7and which is inclined toward the top or second surface11at a predetermined angle21relative to the bottom surface12and horizontal. The hypotenuse side of the undercut reflects light travelling through the planar portion upwardly and toward the top surface11.

Referring now toFIG. 4, an isolated view of the undercut and adjacent areas of the planar portion7are shown in greater detail. The top surface11of the planar portion7is coated with a high refractive index coating23. A black matrix layer27coats the high refractive index coating layer23. A window25is cut or etched through the black matrix layer27but does not extend through the high refractive index coating layer23.

The window25is located in the black matrix layer27over the hypotenuse17of the undercut15. Light from the white light source2thus travels upwardly through the post portion5, is reflected by the beveled outside corner9, travels through the planar portion7, is reflected by the hypotenuse17and emitted through the window25.

Referring now toFIG. 5, a multi-color illuminated pointer cap for an in-vehicle instrument panel is shown. The embodiment shown inFIG. 5differs from that shown inFIG. 4by the addition of two triangular undercuts15and a high refractive index over both the top and bottom surfaces of the planar portion7. The embodiment shown inFIG. 5also differs from that shown inFIG. 4by the addition of two windows25and26formed in the black matrix layer27, the window25being above a first color filter layer29, the second window26being above a second color filter layer31. Both color filter layers are over the high refractive index coating23, which is above the top surface11of the planar portion7.

In addition, the hypotenuse surfaces of the undercut are also coated with the same high refractive index coating23.

In operation, white light emitted from the white light source2travels up the post portion5, is reflected laterally by the beveled edge, which is also preferably coated by the high refractive index coating23. The white light is reflected sideways or laterally into the planar portion where it strikes the inclined hypotenuse surfaces, both of which are coated. The light from the two hypotenuse sides is reflected upwardly and is projected through the differently colored filters thereby providing differently-colored light from the instrument100shown inFIG. 1.

As used herein, the term high-refractive index coating is a material which has a refractive index greater than about 1.3 but up to about 1.8 and higher. In the preferred embodiment, the white light source is a white light emitting diode. In an alternate embodiment, the high-refractive index coating is replaced by a white paint. The black matrix layer27can be a black paint. The windows can be formed by a laser etching or abraiding.

The foregoing description is for purposes of illustration only. The true scope of the invention is set forth in the following claims.