GB2237385A

GB2237385A - Faceplate for back illuminated instrument panel

Info

Publication number: GB2237385A
Application number: GB8923562A
Authority: GB
Inventors: Geoffrey Howard Kerr; Leslie Ward
Original assignee: Delco Electronics Overseas Corp
Current assignee: Delco Electronics Overseas Corp
Priority date: 1989-10-19
Filing date: 1989-10-19
Publication date: 1991-05-01
Anticipated expiration: 2009-10-19
Also published as: GB2237385B; GB8923562D0

Abstract

A faceplate (10) for a back-illuminated instrument panel comprising at least one gauge (48) having gauge graduations (52), a pointer (50), and a light source (34), the faceplate comprising an inner layer of light conducting material 12, an opaque outer layer (14) on one side of the inner layer and having translucent areas (60) and/or windows therein for the illumination of the gauge graduations and the pointer; a first light pipe (16) integral with the other side of the inner layer and having an input face (32) directed towards the light source (34) and a deflective face 62 below the window 58 for the pointer, the first light pipe being capable of transmitting light from the light source to the pointer; and a second light pipe (18) integral with the other side of the inner layer 12 and having an input face (46) directed towards the same light source and deflective faces below the translucent areas or windows for the gauge graduations, the second light pipe being capable of transmitting light from the light source to the gauge graduations. The second light pipe conforms to the arc of the graduated scale of the gauge and has a deflective surface for each gauge graduation. <IMAGE>

Description

FACEPLATE FOR BACK-ILLUMINATED INSTRUMENT PANEL This invention relates to a faceplate for a back-illuminated instrument panel, and in particular to the light input or pick-up arrangement for light pipes.

It has become common practice in motor vehicles to provide the dials or gauges of the instrument panel with back illumination. This is achieved by providing the dial or gauge with an acrylic or similar faceplate and covering the face thereof with suitable opaque material, with windows and/or translucent areas being formed in the opaque material at the positions where graduations for the dial or gauge are required and where the pointer of the gauge is connected to the gauge coil. By suitable moulding of the acrylic plate, light can be transmitted from a light source to the translucent areas by the main body of the acrylic plate to illuminate the graduations of each gauge, and to the windows by a set of light pipes to illuminate the pointers of the dials or gauges.In this arrangement, the input faces of the light pipes are circumferentially arranged around the light source at either the base of the light source or at the upper portion of the light source, with the other portion (that is, the upper portion or the base respectively) of the light source being left open to scatter light to the acrylic plate. This arrangement does not provide efficient use of the light from the light source.

An alternative arrangement is shown in European patent application no. 0 029 638. In this arrangement, a lens is used to transmit light from a light source into the main body of the acrylic plate for illumination of both the gauge graduations and the pointers. No light pipes are used. In practice, however, this arrangement has proved to be inefficient in transmitting light to the gauge graduations and the pointers.

It is an object of the present invention to provide an arrangement by which more efficient use of the light from the light source is made to provide both gauge graduation and pointer illumination.

To this end, a faceplate in accordance with the present invention for a back-illuminated instrument panel comprising at least one gauge having gauge graduations, a pointer, and a light source, comprises an inner layer of light conducting material; an opaque outer layer on one side of the inner layer and having translucent areas and/or windows therein for the illumination of the gauge graduations and the pointer; a first light pipe integral with the other side of the inner layer and having an input face directed towards the light source and a deflective face below the window for the pointer, the first light pipe being capable of transmitting light from the light source to the pointer; and a second light pipe integral with the other side of the inner layer and having an input face directed towards the same light source and deflective faces below the translucent areas or windows for the gauge graduations, the second light pipe being capable of transmitting light from the light source to the gauge graduations.

With the arrangement of the present invention, more efficient use is made of the light emitted from the light source to provide improved illumination of the gauge graduations and pointer of a gauge. Further, by suitable arrangement of the input faces of the first and second light pipes, several gauges can be illuminated from a single light source. The present invention has particular application for an instrument panel of a motor vehicle.

Preferably, the first light pipe comprises a main portion extending in a plane substantially parallel to the plane of the inner layer, a substantially L-shaped portion at one end of the main portion and extending substantially normal to the main portion, and a deflective face at the junction of the main portion and the L-shaped portion, the input face of the first light pipe being directed towards the base of the light source; and the second light pipe comprises a main portion extending in a plane substantially parallel to the plane of the inner layer, an input portion at one end of the main portion of the second light pipe and extending at an acute angle thereto, and a deflective face at the junction of the main portion of the second light pipe and the input portion, the input face of the second light pipe being directed towards the upper portion of the light source.

Alternatively, the second light pipe may comprise a main portion extending in a plane substantially parallel to the plane of the inner layer, a substantially L-shaped portion at one end of the main portion and extending substantially normal to the main portion, and a deflective face at the junction of the main portion and the L-shaped portion, the input face of the second light pipe being directed towards the base of the light source; and the first light pipe may comprise a main portion extending in a plane substantially parallel to the plane of the inner layer, an input portion at one end of the main portion of the first light pipe and extending at an acute angle thereto, and a deflective face at the junction of the main portion of the first light pipe and the input portion, the input face of the first light pipe being directed towards the upper portion of the light source.

In either case, where the faceplate comprises two or more first and second light pipes, preferably the input faces of the first light pipes are arranged to extend circumferentially around the light source; and the input faces of the second light pipes are arranged to extend circumferentially around the light source.

Preferably, the inner layer and the first and second light pipes are moulded in one piece.

The present invention also includes an instrument panel comprising a faceplate as in defined; a gauge for the or each first and second light pipes, the or each gauge comprising gauge graduations and a pointer; and a light source.

The present invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is perspective view, partly cut away, of a portion of a faceplate in accordance with the present invention with the inner layer and opaque outer layer omitted for clarity; Figure 2 is a top view of the portion of the faceplate of Figure 1 with the inner layer and opaque outer layer omitted for clarity; Figure 3 is a cross-section on the line III-III in Figure 2 with the inner layer and opaque outer layer included; Figure 4 is a cross-section on the line IV-IV in Figure 2 with the inner layer and opaque outer layer included; Figure 5 is a front view of another portion of the faceplate shown in Figure 1, including gauge graduations and a pointer; Figure 6 is a cross-section on the line VI-VI in Figure 5; and Figure 7 is a cross-section on the line VIl-VIl in Figure 5.

Referring to Figures 1 to 4, a faceplate 10 in accordance with the present invention for a -back-illuminated instrument panel comprises an inner layer 12 of light transmitting material, such as acrylic, with an opaque outer layer 14 on one side thereof. Integral with the other side of the inner layer 12 is a number of pairs of light pipes 16,18; 20,22; 24,26. The inner layer 12 and the light pipes 16-26 are preferably moulded in one-piece. The present invention has particular application for an instrument panel of a motor vehicle.

Each pair of light pipes 16,18; 20,22; 24,26 is associated with a gauge 48, part of one of which is shown in Figures 5 to 7, and which will be described in more detail below. One of the pairs of light pipes 16,18 comprises a first light pipe 16 and a second light pipe 18. The first light pipe 16 comprises a main portion 28 extending in a plane substantially parallel to the plane of the inner layer 12, with a substantially L-shaped portion 30 attached to one end of the main portion substantially normal to the main portion. The L-shaped portion 30 has an input face 32 directed towards the base of a light source 34 in the form of a bulb 36. A deflective face 38 is formed at the junction of the main portion 28 and the L-shaped portion 30.Light from the bulb 36 passes into the first light pipe 16 through the input face 32 and is reflected off the deflective face 38 into the main portion 28 for transmission therealong.

The second light pipe 18 also comprises a main portion 40 extending in a plane substantially parallel to the plane of the inner layer 12, but with an input portion 42 attached to one end of the main portion 40 and extending at an acute angle to the main portion. A deflective face 44 is formed at the junction of the main portion 40 and the input portion 42. The input portion 42 has an input face 46 directed towards the upper portion of the bulb 36.

Light from the bulb 36 passes into the second light pipe 18 through the input face 46 and is reflected off the deflective face 44 into the main portion 40 for transmission therealong.

The other pairs of light pipes 20,22; 24,26 have substantially identical arrangements of first and second light pipes as the above described pair of light pipes 16,18. The input faces 32 of the first light pipes 16,20,24 of each pair are arranged to extend circumferentially around the base of the bulb 36. Similarly, the input faces 46 of the second light pipes 18,22,26 of each pair are arranged to extended circumferentially around the upper portion of the bulb 36.

Referring now to Figures 5 to 7, the gauge 48 comprises a pointer 50 and gauge graduations 52.

The pointer 50 is moulded from light transmitting material such as acrylic, and is mounted on a pin 54 to pivot about axis A. The pin 54 passes through an aperture 55 in the inner layer 12 and is driven by the remaining parts of the gauge 48 which are well known and will not be described or shown here. The mounting portion 56 of the pointer 50 is rotatably positioned in a window 58 in the opaque outer layer 14 of the faceplate 10. The gauge graduations 52 are defined by translucent areas 60 in the opaque outer layer 14. The translucent areas 60 are usually formed by suitable printing techniques. As an alternative, the translucent areas may be replaced by windows.

The first light pipe 16 of the pair of light pipes 16,18 transmits light to the pointer 50 by way of a deflective face 62 in the first light pipe which extends circumferentially around the pin 54 and is aligned with the window 58, and a deflective face 64 on the mounting portion 56 of the pointer 50. The second light pipe 18 transmits light to the gauge graduations 52 by way of deflective faces 66 in the second light pipe, each deflective face 66 being aligned with a corresponding translucent area 60 in the opaque outer layer 14.

Similarly, the other pairs of light pipes 20,22; 24,26 transmit light to other gauges.

The deflective faces 38,62,64,66 are substantially at 45 degrees to the plane of the inner layer 12. The angle of the deflective face 44 to the plane of the inner layer 12 is dependent on the angle of the input portion 42 of the second light pipe 18,24,26. In a preferred arrangement, the angle of the input portion 42 is approximately 63 degrees, and the angle of the deflective face 44 is approximately 33 degrees.

In the faceplate 10 of the present invention, first and second light pipes 16,18 respectively are used to transmit light to the pointer 50 and the gauge graduations 52 of a gauge 48. This has proved to be a far more efficient method for illuminating the pointer 50 and gauge graduations 52 of a gauge 48 than previously known arrangements. Further still, the arrangement of the input faces 32,46 of the first and second light pipes 16,18 respectively is such as to make maximum use of light emitted from the light source 34. Whilst the above described arrangement shows three pairs of light pipes around a single light source, the present invention is not restricted to such an arrangement, as any numbered of pairs of light pipes may be arranged around a single light source. Further, the input arrangement of the first and second light pipes may be reversed such that the L-shaped portion is part of the second light pipe, and the angled input portion is part of the first light pipe. In this case, the input faces of the first light pipes would be directed to the upper portion of the light source, and the input faces of the second light pipes would be directed towards the base of the light source.

Claims

Claims:

1. A faceplate for a back-illuminated instrument panel comprising at least one gauge having gauge graduations, a pointer, and a light source, the faceplate comprising an inner layer of light conducting material; an opaque outer layer on one side of the inner layer and having translucent areas and/or windows therein for the illumination of the gauge graduations and the pointer; a first light pipe integral with the other side of the inner layer and having an input face directed towards the light source and a deflective face below the window for the pointer, the first light pipe being capable of transmitting light from the light source to the pointer; and a second light pipe integral with the other side of the inner layer and having an input face directed towards the same light source and deflective faces below the translucent areas or windows for the gauge graduations, the second light pipe being capable of transmitting light from the light source to the gauge graduations.

2. A faceplate as claimed in Claim 1, wherein the first light pipe comprises a main portion extending in a plane substantially parallel to the plane of the inner layer, a substantially L-shaped portion at one end of the main portion and extending substantially normal to the main portion, and a deflective face at the junction of the main portion and the L-shaped portion, the input face of the first light pipe being directed towards the base of the light source; and wherein the second light pipe comprises a main portion extending in a plane substantially parallel to the plane of the inner layer, an input portion at one end of the main portion of the second light pipe and extending at an acute angle thereto, and a deflective face at the junction of the main portion of the second light pipe and the input portion, the input face of the second light pipe being directed towards the upper portion of the light source.

3. A faceplate as claimed in Claim 1, wherein the second light pipe comprises a main portion extending in a plane substantially parallel to the plane of the inner layer, a substantially L-shaped portion at one end of the main portion and extending substantially normal to the main portion, and a deflective face at the junction of the main portion and the L-shaped portion, the input face of the second light pipe being directed towards the base of the light source; and wherein the first light pipe comprises a main portion extending in a plane substantially parallel to the plane of the inner layer, an input portion at one end of the main portion of the first light pipe and extending at an acute angle thereto, and a deflective face at the junction of the main portion of the first light pipe and the input portion, the input face of the first light pipe being directed towards the upper portion of the light source.

4. A faceplate as claimed in Claim 2 or Claim 3 comprising two or more first and second light pipes, wherein the input faces of the first light pipes are arranged to extend circumferentially around the light source; and wherein the input faces of the second light pipes are arranged to extend circumferentially around the light source.

5. A faceplate as claimed in any one of Claims 1 to 4, wherein the inner layer and the first and second light pipes are moulded in one piece.

6. A faceplate substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

7. An instrument panel comprising a faceplate as claimed in any one of Claims 1 to 6; a gauge for the or each first and second light pipes, the or each gauge comprising gauge graduations and a pointer; and a light source.