Gradient dot pattern for reducing visible step lines on the face of an applique

Various manufacturing techniques may be employed to construct an appliqué for use in an instrument cluster. In one commonly employed technique, an appliqué may be formed by applying different colored ink layers onto a surface of a polycarbonate sheet using a silk screen printing. In some instance, an edge of an underlying ink layer may cause a visible step line on the face of the appliqué. To reduce or eliminate these visible step lines, an outer boundary area of the printing layers invention are defined as a dispersing dot pattern.

FIELD OF THE INVENTION

The present invention relates generally to vehicle instrument clusters and, more particularly, to a technique for reducing visible step lines on the face of an appliqué for an instrument cluster.

BACKGROUND OF THE INVENTION

Various manufacturing techniques may be employed to construct an appliqué for use in an instrument cluster. In one commonly employed technique, an appliqué may be formed by applying different colored ink layers onto a surface of a polycarbonate sheet using a well known silk screen printing process. The different colored ink layers are typically applied to different areas along the surface of the polycarbonate sheet. These different colored ink layers are then covered by a layer of black colored ink which serves as the visible face of the appliqué. The outer most black colored ink layer is selectively applied onto the surface, thereby forming visible red graphics on the face of the appliqué. In some instance, an edge of an underlying ink layer may cause a visible step line on the face of the appliqué as shown inFIG. 5A. The appliqué may undergo some additional deformation process which may further cause a visible step line on the face of the applique as shown inFIG. 5B. Therefore, it is desirable to provide a technique for reducing or eliminating visible step lines on the face of an appliqué for an instrument cluster.

SUMMARY OF THE INVENTION

Rather than employing underlying printing layers which have sharp edges, the printing layers of the present invention include an outer boundary area defined as a dispersing dot pattern, thereby enabling a smoother transition in height amongst the different printing layers and reducing or eliminating any visible step lines on the face of the appliqué.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1depicts an exemplary instrument cluster10in an automotive vehicle. The instrument cluster10may include various gauges and dials which are to viewed and/or operated by an occupant of the vehicle. For example, a speedometer12may be used to display the speed which a vehicle is traveling. The speedometer includes a movable pointer14which correlates to the speed of the vehicle. To provide meaningful graphical information to the occupant, an appliqué16forms the background for the pointer14of the speedometer. In this example, the appliqué for the speedometer provides a scale of numbers, such that the pointer is operable to point to the applicable number which corresponds to the speed of the vehicle.

Referring toFIGS. 2-4, a method for constructing a viewed component, such as an appliqué for an instrument cluster, is further described in accordance with the present invention. While the following description is provided with reference to an appliqué for use in an instrument cluster, it is readily understood that the broader aspects of the present invention are applicable to any viewed component whose visible face may include a visible step line caused by an underlying layer.

A viewed component is constructed from a planar sheet22of suitable material. The planar sheet22is initially die cut or otherwise sized into a desired shape. Thus, the properly sized planar sheet serves as a substrate for the remainder of the construction process. Although the planar sheet is preferably comprised of a polycarbonate material, it is readily understood that other materials are within the scope of the present invention.

Graphical indicators may be formed by applying different colored ink layers onto the surfaces of the planar sheet. To form the red numbers found on the face of a speedometer, for example, a red colored ink layer24is printed on a front side surface of the planar sheet22as shown inFIG. 2A. The different colored ink layers may be applied to the planar sheet using a silk screen printing process or other various known manufacturing techniques. Since different colored graphics may appear on the appliqué, the red colored ink layer24is only applied to a portion of the planar sheet22. Thus, the red colored ink layer24defines a top surface32, a bottom surface34and an outer boundary area36, such that the bottom surface34faces the planar sheet22.

Rather than forming the outer boundary area36as a sharp edge, the outer boundary area36is formed as a dispersing dot pattern. The dot pattern includes a plurality of spatially separated dots, where the spatial separation between dots gradually increases along a direction outwardly from the outer boundary of the layer. In an exemplary embodiment, each dot in the pattern has a cylindrical shape, such that the radial dimension for the dots gradually decreases in a direction outwardly from the outer boundary. Although dots having a cylindrical shape are described herein, it is readily understood that other geometric shapes are also within the scope of the present invention.

Referring toFIG. 2B, the red colored ink layer24is then covered by a black colored ink layer26that serves as the visible face of the appliqué. To form the desired graphical symbols, the black colored ink layer26is selectively printed onto the planar sheet, thereby exposing portions of the underlying red colored ink layer24. As noted above, the black colored ink26may be selectively applied to the planar sheet using a silk screen printing process or another known manufacturing technique. It is readily understood that other underlying colored layers may also be printed onto the planar sheet prior to the application of black colored ink layer26.

In accordance with the present invention, the dispersing dot pattern formed along the outer boundary layer of each underlying printed layer enables a smoother height transition amongst the different printed layers. During application of the black colored ink layer26over top of the red colored ink layer24, a downward force reduces the height of at least some of the dots along the outer boundary area of the red colored ink layer. Specifically, dots disposed further away from the outer edge are reduced in height more than those closer to the outer edge of the red colored ink layer. As a result, the outer boundary area exhibits a profile which slopes gradually downward from the top surface towards the planar sheet, thereby reducing or eliminating the visible appearance of a pronounced step line along the outer edge of the underlying printed layer.

Furthermore, the viewed component may be backlit to facilitate viewing of the component during dark conditions. In these instances, the viewed component may include additional layers formed on the backside of the planar sheet. Referring toFIGS. 3A and 4A, a black colored ink layer42may be printed onto the entire backside surface of the planar sheet22. A white colored ink layer44is then printed over top of the black colored ink layer42in select areas. The white colored ink layer44defines an inner surface52, an outer surface54and an outer boundary area56, such that the inner surface faces the planar sheet22. In this way, the white bottom layer improves backlighting as is well known in the art. However, the viewed component may undergo a further deformation process that can cause the formation of a visible step line. Exemplary deformation processes include (but not limited to) a high pressure forming process, a vacuum forming process or a hydroforming process.

To reduce or eliminate a visible step line, the outer boundary area56of the outer white layer44is likewise formed as a dispersing dot pattern. As described above, the dot pattern includes a plurality of spatially separated dots, where the spatial separation between dots gradually increases along a direction outwardly from the outer boundary of the layer as best seen inFIG. 3B. Although not limited thereto, each dot in the pattern is of a cylindrical shape, such that the radial dimension for the dots gradually decreases in a direction outwardly from the outer boundary.

During the deformation process, the dispersed dot pattern along the outer boundary of the white colored layer44enables a smoother height transition amongst the different printed layers. Referring toFIG. 4B, the height of at least some of the dots are reduced as pressure is applied to the viewed component. Again, dots disposed further away from the outer edge are reduced in height more than those closer to the outer edge of the red colored ink layer. Thus, the outer boundary area exhibits a sloped profile, thereby reducing or eliminating the visible appearance of a pronounced step line along the visible face of the applique.