Pointer cap illumination

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.

FIG. 1 is a perspective view of an instrument panel display device, e.g., a tachometer, which provides a multi-color light output, the colors of which are obtained from a single, white light source;

FIG. 2 is a “top” view of the display device shown in FIG. 1 ;

FIG. 3 is a sectional view of the device shown in FIG. 1 and FIG. 2 through section lines A-A;

FIG. 4 is an isolated view of a portion of the display device shown in FIGS. 1-3 ; and

FIG. 5 is an isolated view of an alternate embodiment of the device shown in FIGS. 1-3 .

FIG. 1 is a perspective view of a multi-color display 100 for an instrument panel. In FIG. 1 , the device is a tachometer. The display device 100 comprises a circuit board 1 , 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” 5 and a “planar portion” 7 .

The display has a multi-color light output from the top surface 11 of the planar portion 7 , the planar portion 7 being supported by and attached to a post portion 5 . The top surface 11 has a beveled peripheral edge 13 , the outside corner of which is identified by reference numeral 9 .

FIG. 2 is a top view of the device shown in FIG. 1 . The planar portion 7 has a top surface 11 and an opposing bottom surface 12 . The post portion 5 and the planar portion 7 are a unitary structure made of a light-transmissive acrylic or a polycarbonate. As used herein, the post portion 5 and the planar portion 7 are considered to be a light-transmissive acrylic or polycarbonate substrate, which is optically coupled to the white light source 2 , which is attached to the circuit board 1 .

FIG. 3 is a sectional view of the device shown in FIG. 1 and FIG. 2 taken through section lines A-A. The post portion 5 is essentially a column, i.e. it is considered herein to be substantially columnar. It has a first end 6 directly above the white light source 2 . An opposing second end 8 has the beveled outside corner 9 and is a contiguous or unitary structure with the planar portion 7 . Since the columnar post portion 5 and the planar portion 7 are a unitary structure and made from a light-transmissive acrylic, light that is emitted from the light source 2 is coupled into the substantially planar first end of the post portion 5 , travels upwardly through the post portion 5 and is reflected by the beveled outside corner sideways or laterally into the planar portion 7 .

Still referring to FIG. 3 , the planar portion 7 is provided with an undercut 15 which is essentially a triangular-shaped cut formed into the lower or bottom surface 12 of the planar portion 7 . The undercut 15 has a hypotenuse 17 which extends into the planar portion 7 and which is inclined toward the top or second surface 11 at a predetermined angle 21 relative to the bottom surface 12 and horizontal. The hypotenuse side of the undercut reflects light travelling through the planar portion upwardly and toward the top surface 11 .

Referring now to FIG. 4 , an isolated view of the undercut and adjacent areas of the planar portion 7 are shown in greater detail. The top surface 11 of the planar portion 7 is coated with a high refractive index coating 23 . A black matrix layer 27 coats the high refractive index coating layer 23 . A window 25 is cut or etched through the black matrix layer 27 but does not extend through the high refractive index coating layer 23 .

The window 25 is located in the black matrix layer 27 over the hypotenuse 17 of the undercut 15 . Light from the white light source 2 thus travels upwardly through the post portion 5 , is reflected by the beveled outside corner 9 , travels through the planar portion 7 , is reflected by the hypotenuse 17 and emitted through the window 25 .

Referring now to FIG. 5 , a multi-color illuminated pointer cap for an in-vehicle instrument panel is shown. The embodiment shown in FIG. 5 differs from that shown in FIG. 4 by the addition of two triangular undercuts 15 and a high refractive index over both the top and bottom surfaces of the planar portion 7 . The embodiment shown in FIG. 5 also differs from that shown in FIG. 4 by the addition of two windows 25 and 26 formed in the black matrix layer 27 , the window 25 being above a first color filter layer 29 , the second window 26 being above a second color filter layer 31 . Both color filter layers are over the high refractive index coating 23 , which is above the top surface 11 of the planar portion 7 .

In addition, the hypotenuse surfaces of the undercut are also coated with the same high refractive index coating 23 .

In operation, white light emitted from the white light source 2 travels up the post portion 5 , is reflected laterally by the beveled edge, which is also preferably coated by the high refractive index coating 23 . 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 instrument 100 shown in FIG. 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 layer 27 can 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.