Integrated low profile display

A panel, such as a component carrier or substrate, is provided with one or more penetrations. A light source associated with a surface of the panel and the corresponding end of each penetration provides light to the interior of the penetration, which guides the light to the other end of the penetration and corresponding surface of the panel. The penetration can be coated with a reflective material to improve its performance as a light guide. Alternatively or additionally, the penetration can be filled with a refractive material. A diffuser can be provided to diffuse light exiting the penetration. The light sources provides light to selected penetrations on demand such that the penetrations function as displays or elements of a display.

BACKGROUND OF THE INVENTION

1. The Technical Field

The present invention relates generally to displays used in man/machine interfaces. More particularly, the present invention relates to integration of such displays into wiring boards, equipment panels and other substrates.

2. The Prior Art

Displays often are used to visually communicate information to a user of machines as diverse as coffee makers and industrial presses. Such displays can be embodied in many forms. For example, a simple display might take the form of one or more lights that illuminate selectively to indicate the status of a machine (e.g., energized, running, stopped). A more complex display might include one or more multi-segment or dot matrix elements for providing alphanumeric information (e.g., temperature, pressure, time). A conventional display typically is provided as a pre-manufactured component or sub-assembly for later mounting to a carrier or substrate, typically a printed wiring board or other component or panel of a machine. The substrate or carrier may include other include other electrical/electronic components, for example, proximity sensors.

Conventional displays can be complicated and expensive to build. Indeed, some applications might even require custom-made displays. This can make them unsuitable for low-cost applications. Also, conventional displays have a finite thickness. When mated to a machine panel or other substrate, even a relatively thin conventional display might be too thick for integration into an application requiring a low overall profile.

SUMMARY OF THE INVENTION

The present invention overcomes these and other shortcomings of the prior art by integrating a display into a component carrier or substrate, for example, a printed wiring board or panel of an apparatus in connection with which the display is to be used, thus obviating the need for a separate display component. Other components, such as sensors, can be integrated into the assembly, as well. Without limitation, sensors as described in U.S. Pat. No. 5,594,222, No. 6,310,611 and No. 6,320,282, the teachings of which are incorporated herein by reference, are well suited for such an application.

In a preferred embodiment, the substrate is of substantially uniform thickness and relatively thin compared to its length and width. However, the substrate may embody any other shape and cross section, as well. Thus, the first and second surfaces may be, but need not be, substantially parallel. The substrate typically would be embodied as a printed wiring board, but could be embodied in any other number of other forms. For example, the substrate could be an exterior panel of an appliance or the dash panel of an automobile.

In a preferred embodiment, the substrate defines one or more penetrations therethrough, each such penetration having a side wall, an entrance opening and an exit opening. The penetration can be of any regular or irregular shape, for example, round, square or elliptical, and it can be formed using any suitable molding, forming or machining technique, for example, NC drilling or punching, among others. A light source is associated with the entrance opening and is configured to selectively direct or otherwise admit light to the penetration through the entrance opening. Preferred light sources include lamps, LEDs, OLEDs, PLEDs, though others can be used, as well.

The penetration serves as a light guide. To this end, the side wall of the penetration preferably is coated with a reflective material, for example, white paint or a reflective metal, so that light introduced to the penetration is transmitted therethrough and not dissipated into the substrate. In other embodiments, the side wall could be coated with any substantially opaque material which precludes diffusion of light into the substrate. Further, the side wall could be left uncoated if the substrate were made of a material which does not substantially transmit light. In the foregoing embodiments, light entering the penetration at the entrance opening reflects off the side wall and exits the penetration at the exit opening.

Alternatively, the penetration serves as a housing for a light guide. In such a preferred embodiment, the penetration is substantially filled with a material having a high refractive index, for example, a light transmissive epoxy having good optical properties. In this embodiment, light entering the refractive material from the entrance opening reflects off the internal walls of the refractive material and exits the refractive material at the exit opening. Thus, the refractive material acts as a light guide. In another embodiment, a discrete light guide could be installed in the penetration.

In a preferred embodiment, a light diffuser is associated with the exit opening of the penetration. The diffuser diffuses light exiting the penetration to enhance readability of the display by the user. Such light diffuser typically would be embodied as a layer of light transmissive material applied over the exit opening.

In an alternate embodiment, the substrate defines one or more cavities, instead of (or in addition to) the foregoing penetrations. Each cavity includes a side wall and an entrance opening. Such cavities do not completely penetrate the substrate. Thus, each cavity includes a closed end instead of an exit opening. These cavities can be molded into the substrate or formed into the substrate using any suitable machining technique. In this embodiment, at least the portion of the substrate between the closed end of the cavity and the second surface of the substrate is transparent or translucent so that light may be transmitted therethrough. The side wall of the cavity preferably is coated in the manner discussed above to preclude light dispersion into the substrate.

Alternatively, the cavity can be filled with a refractive material, as discussed above. In this embodiment, the portion of the substrate between the closed end of the cavity and the second surface of the substrate performs the function of the light diffuser of the embodiment described above.

A display according to the invention can mimic conventional single element or multiple element displays. Typically, a single penetration or cavity would be used to mimic a single element display, such as a status indicator light, or the individual elements of a multiple element display. For example, seven penetrations or cavities arranged in the manner of a conventional seven-segment display could mimic such a conventional display. Other configurations are possible, as well. Further, any practical number of displays can be located on the same substrate. Thus, the present invention is well-suited to applications requiring multiple displays.

The substrate can include other components commonly present in man/machine interfaces, such as sensors and other electrical or electronic components. Integration of such components with the display can further reduce the cost, complexity, and size of an end component. The substrate also can include decoration, texture, and the like, for functional or purely decorative purposes.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

FIGS. 1A and 1Billustrate a preferred embodiment of an integrated display10according to the present invention. Display10includes a substrate12having a first surface14and a second surface16. Substrate12can be embodied as virtually any type of substrate, carrier, panel, etc. Although illustrated as planar and having uniform thickness, substrate12can take any virtually any other form. For example, it can have regularly or irregularly varying non-uniform thickness. It can be curved, rippled, or have any variety of complex shapes and cross-sections. In a typical embodiment, substrate12might be a printed wiring board, such as an FR4 board with a one-half ounce copper layer and an OSP or HASL finish. In other embodiments, substrate12could be an exterior panel of a domestic appliance, such as a coffee maker or washing machine, a dash panel or other interior panel of an automobile, or a panel of any other machine or piece of equipment. These are but a few examples of substrates into which a display can be integrated according to the present invention. Further, although first surface14and second surface16are illustrated as generally opposed, parallel surfaces, first and second surfaces14and16could be related in any number of other ways. For example, first and second surfaces14and16could be at right angles to each other.

Substrate12, as illustrated inFIG. 1B, includes two rectangular penetrations18. In other embodiments, substrate12may include more or fewer than two such penetrations, and such penetrations may be of any regular or irregular shape, including, without limitation, circular, square, elliptical or free form. Penetrations18may be formed by drilling, molding, punching, or other suitable techniques. Each penetration18includes an entrance opening20, an exit opening22and a side wall24.

Penetrations18function as light guides or housings for light guides. Light is coupled from a light source into entrance opening20. The light reflects off of the internal walls of the light guides so that the light ultimately leaves the light guide at the exit opening.

In a preferred embodiment, as illustrated inFIG. 1A, penetrations18function as light guides. In order to best enable penetration18to function as a light guide, side wall24preferably is impervious to light transmission to prevent light dissipation or diffusion through substrate12. To this end, side wall24preferably is plated with a reflective coating26, as shown inFIG. 1A. In alternate embodiments, side wall24can be coated with, for example, white paint or other non-transparent materials. Conceivably, side wall24could be left uncoated. In such an embodiment, substrate12preferably would be made of a material which inherently reflects light or does not substantially transmit light because such materials would tend to reduce light dissipation through the substrate. In an alternate embodiment, as illustrated inFIG. 2, penetrations18function as housings for light guides. In this embodiment, penetrations18are filled with an epoxy material28having a high refractive index, with the epoxy material comprising the light guide. Such material allows light transmission though penetrations18, from the first side to the second side of substrate12, but prevents or retards light dispersion into substrate12. Other materials having desirable optical, mechanical and electrical properties can be used in lieu of epoxy28. In another embodiment, not shown in the drawings, a discrete light guide, such as a light pipe could be installed in penetration18. In the foregoing embodiments, side wall24can be, but need not be coated as described above in connection with theFIG. 1Aembodiment. A separate light pipe assembly with apertures built into it could serve as the light guide in a similar fashion.

A display according to the present invention can include a diffuser30located at or near exit opening22. The purpose of diffuser30is to diffuse light exiting penetration18which might otherwise be channelized, thus enhancing readability of the display by the user. To this end, diffuser30can be made of any variety of light transmissive materials. In preferred embodiments, diffuser30can cover a substantial portion of second surface16, as shown inFIGS. 1A and 2, or it can simply cover a smaller portion of second surface16proximate exit opening22. Diffuser30can include printing or other decoration (not shown) to enhance the functionality of the display (and of any other components associated with the substrate), or for purely decorative purposes. Diffuser30can be embodied as, for example, a fascia, an overlay, a piece of glass, or any other structure that aids in diffusing light exiting penetration18. Display10further includes a light source34adapted to introduce light to entrance opening20, as shown inFIGS. 1A,1B and2. Preferably, light source34takes the form of a low profile LED mounted to first surface14of substrate12, proximate entrance opening20. In other embodiments, light source34could be a lamp, an EL, OLED, PLED, vacuum fluorescent or light source. Although light source LED is illustrated in a particular orientation with respect to penetration18, other orientations are possible, as well.

In another embodiment illustrated inFIG. 3, substrate12defines one or more cavities18A in lieu of (or in addition to) penetrations18. Cavities18A are similar to and provide essentially the same function as penetrations18, except that cavities18A do not completely penetrate substrate12. Instead, a thin layer of substrate material12A remains where exit opening22is located in theFIGS. 1A and 2embodiments. Thus, each cavity18A includes an entrance opening20, a side wall24and a closed end32. Side wall24of cavity18A can be coated with a reflective or other non-transparent material (not shown), as discussed above, so that cavity18A can function as a light guide. Alternatively, cavity18A can be filled with a refractive material (not shown), as discussed above, which can function as a light guide. In such embodiments, at least thin layer of substrate material12A is transparent or translucent so that light may be transmitted therethrough and be visible to the user. Thus, thin layer of substrate material12A can function as a diffuser, obviating any need for a separate diffuser, such as diffuser30as illustrated inFIGS. 1A and 2and described above. Notwithstanding, a separate diffuser30may be layered or screen-printed on surface16.

In another alternate embodiment, illustrated inFIG. 4, the light source is disposed on a carrier, for example, a printed wiring board, separate from the substrate comprising the light guide. Here, light sources34, for example, surface mount LEDs, are disposed on carrier112A, which can include other components, such as sensors, as discussed above. Substrate112B includes cavities18A, as discussed above. In other embodiments, substrate112B could include penetrations in addition to or in lieu of cavities18A. Carrier112A is attached to substrate112B using adhesives or other suitable attachment means such that light sources34mounted on carrier34are substantially aligned with cavities18A (and/or penetrations) in substrate112B. An optional diffuser130can be attached to the viewed surface (here, the opposing surface) of substrate112B, as described above.

In practice, a seven-segment display could be constructed by tooling (such as by punching or NC drilling) or molding a substrate (such as a printed wiring board) with penetrations corresponding to the seven segments, plating the side walls of the penetrations using known plating techniques, and attaching a suitable light source (such as a surface-mount LED of appropriate color) proximate the entrance opening of each penetration using a suitable technique (such as a reflow-solder technique, using known surface-mount component process equipment), opposite the exit opening and any diffuser or fascia that might be located proximate the exit opening. Other user interface components (such as sensors or other components) could be mounted to the substrate at the same time or as a step during the same production process, thus reducing overall manufacturing cost and yielding an interface of smaller size than could be manufactured using conventional discrete components. For example, a sensor40can be mounted on the first surface14of substrate12, as shown inFIG. 1B. A sensor could be mounted on other portions of display10as well. The illustrated sensor40includes a first electrode42, a second electrode44, and an active component or integrated circuit46. Other types of sensors or components could be used instead of or in addition to the illustrated sensor. In another embodiment, the penetrations could be filled with a material, such as an epoxy, having an appropriate refractive index, in lieu of plating. In further embodiment, the substrate could be tooled or molded with cavities instead of penetrations, the penetrations could be filled with a refractive material or the side walls thereof could be plated.

The present invention is limited only by the following claims and not the foregoing embodiments. One skilled in the art would know to make certain modifications to the foregoing embodiments without departing from the scope of the claims.