GB2262806A - Apparatus for illuminating an instrument display - Google Patents

Abstract

A gauge case (14) of an instrument cluster is formed with a convex lens (18) in a rear wall thereof. A light bulb (22) provided in a light tube (24) is adapted to direct light through the lens (18) to an indicator symbol (10), which may be a low fuel level or low battery voltage level indicator, of an appliqué (12) of the instrument cluster. The arrangement is readily incorporated into an instrument cluster. <IMAGE>

Description

APPARATUS FOR ILLUMINATING AN INSTRUMENT DISPLAY The present invention relates to apparatus for illuminating an indicator symbol of an instrument display, and to a gauge case adapted for use therewith.

The invention is particularly useful in instrument clusters of vehicles.

It is common to provide on appliques of vehicle instrument display panels, in addition to a variety of instrument scales, a plurality indicator symbols to indicate important information such as low fuel level and low battery voltage. These indicator symbols are generally illuminated from behind the instrument panel by means of a light bulb placed in a light tube which comes substantially into contact with the applique. The light tube acts to direct the light from the light bulb to the indicator symbol and also ensures that no stray light from the light bulb illuminates other such symbols.

A problem with this arrangement is that the light tube can obstruct the instruments or other components in the instrument cluster, which generally means that the indicator symbol has to be placed at a distance from its associated scale, which can sometimes make it difficult to notice the indicator.

The present invention seeks to provide improved apparatus for illuminating an indicator symbol of an instrument display.

According to an aspect of the present invention, there is provided apparatus for illuminating an indicator symbol of an instrument display from behind the normal viewing surface of the display, comprising a gauge case including a converging lens, and a light source adapted to pass light through the lens of the gauge case such that in use light from the light source is focussed onto the indicator symbol.

In this manner, the actual components can be located at a distance from the display panel so as not to obstruct the gauge mechanism or other instrument components. It has been found that due to the focussing of the light beam onto the indicator symbol, it is possible to have part of the gauge mechanism or other instrument components fall within the light beam without significantly affecting the intensity with which the indicator symbol is illuminated. This can substantially ease the incorporation of such a feature into an instrument cluster.

Preferably, the converging lens is provided in a wall of the gauge case. In this manner, the lens can be moulded as part of the gauge case, which makes it particularly cheap to produce and easy to implement.

In an embodiment, the gauge case is made of a substantially light transparent material. This enables the scale associated with the gauge, and also the indicator symbol to be back-lit for night-time viewing.

This is particularly useful when the indicator symbol is one of the graduations of the scale, so that it can be illuminated at two different intensities, the lower intensity being background lighting and the higher intensity giving the warning. In connection with this, the apparatus may comprise illuminating means adapted to illuminate the indicator symbol at a relatively lower intensity level than the intensity level provided by the light source.

Advantageously, the apparatus comprises a light tube adapted to direct light from the light source to the lens, the inner wall or walls of the light tube preferably being light reflective. The light tube can ensure that most or all of the light from the light source is directed to the lens, and hence to the indicator, and that substantially no stray light from the light source illuminates any other symbols.

Another aspect of the present invention provides a gauge case for use in an instrument comprising a lens disposed in a wall of the case and adapted to focus light onto an indicator symbol of a display of the instrument.

In an embodiment, the gauge case is substantially transparent.

An embodiment of the present invention is described below, by way of illustration only, with reference to the accompanying drawings, in which: Figure 1 shows a cross-sectional view of an embodiment of indicator symbol illuminating apparatus fitted behind an applique of an instrument cluster; and Figure 2 shows a front elevational view of a scale of the applique of Figure 1.

Referring to Figure 1, there can be seen in cross-section an indicator symbol 10 on an applique 12 of a vehicle instrument display panel. The indicator symbol 10 may be representative of a low fuel level or of low battery voltage, or of any other suitable parameter. It is formed of a layer of translucent material, preferably coloured, on a generally opaque and dark surface.

As can be seen from Figure 2, the indicator symbol 10 is the lower graduation of a scale of the instrument and is therefore particularly adapted to emphasize that the parameter being measured has reached the bottom of the scale. It is generally of a different colour to the rest of the scale.

Referring again to Figure 1, behind the normal viewing surface of the applique 12, that is within the instrument cluster, there is provided a gauge case 14 for supporting a gauge mechanism (not shown). In this embodiment, the gauge case 14 comprises an annular supporting member 20 which abuts the rear surface of the applique 12 to ensure the correct disposition of the gauge case relative to the applique. The case 14 is substantially transparent, and has formed integrally in its rear wall 16 a convex optical lens 18. The lens 18 is disposed so as to be substantially directly behind the indicator symbol 10.

A light bulb 22 is fitted within a substantially cylindrical light tube 24 which is formed of a reflective substance, or alternatively has its walls painted of a light reflective colour, and which is mounted on the gauge case 14 such that the lens 18 sits within the cylindrical wall of the light tube 24.

A supporting wall 26 is provided at an end of the light tube 24 remote from the lens 18 for supporting the light bulb 22 in an aperture 28 thereof and also for securing the light tube in the instrument cluster.

In addition to reflecting light from the light bulb 22 towards the lens 18, the light tube 24 also serves to prevent any light from the light bulb 18 from straying into the instrument cluster.

In use, light from the light bulb 22 is directed by the light tube 24 towards the lens 18 which focusses the light beam onto the indicator symbol 10.

The outer bounds of the main light beam can be clearly seen by the dotted lines in Figure 1. In this manner, the indicator symbol 10 is illuminated brightly so as to be readily discernible by the driver.

The gauge mechanism can move anywhere within the shaded area 30 shown in Figure 1 without falling within the path of the light from the light bulb 22.

However, it has been found that even if part of the gauge mechanism does fall within this light path, the illumination of the indicator symbol 10 is not significantly affected.

Other light bulbs, not shown, are provided in the instrument cluster to illuminate the scales on the applique for night-time viewing. The transparency of the gauge case 14 enables the scale falling within the gauge case 14 and also the indicator symbol 10 to be illuminated. With only these other light bulbs being lit, the indicator symbol 14 is illuminated at a first, lower level and only becomes illuminated at a greater level, so as to give the driver the required warning, when the light bulb 22 is lit.

The instrument cluster may also be provided with a light guide. This is a transparent moulding which is sometimes fitted behind the applique to provide more even illumination of the scales and other graphic symbols on the applique and to provide light for illuminating the pointers of the gauges in the instrument cluster. When such a light guide is provided, this will fit between the gauge case 14 and the applique 12, and will preferably also have an aperture therein in the region of the indicator symbol 10 to avoid loss of any of the light from the light bulb 22 through dispersion in the light guide.

Claims (12)

Claims:

1. Apparatus for illuminating an indicator symbol of an instrument display from behind the normal viewing surface of the display, comprising a gauge case including a converging lens, and a light source adapted to pass light through the lens of the gauge case such that in use light from the light source is focussed onto the indicator symbol.

2. Apparatus according to claim 1, wherein the converging lens is provided in a wall of the gauge case.

3. Apparatus according to claim 1 or 2, wherein the lens is a convex lens.

4. Apparatus according to claim 1, 2 or 3, wherein the gauge case is made of a substantially transparent material.

5. Apparatus according to any one of claims 1 to 4, comprising a light tube adapted to direct light from the light source to the lens.

6. Apparatus according to claim 5, wherein the inner wall or walls of the light tube are light reflective.

7. Apparatus according to any preceding claim, comprising illuminating means adapted to illuminate the indicator symbol at a relatively lower intensity level than the intensity level provided by the light source.

8. A gauge case for use in an instrument comprising a lens disposed in a wall of the case and adapted to focus light onto an indicator symbolof a display of the instrument.

9. A gauge case according to claim 8, wherein the lens is formed integrally with the gauge case.

10. A gauge case according to claim 8 or 9, wherein the gauge case is substantially transparent.

11. Apparatus for illuminating an indicator symbol of an instrument display substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

12. A gauge case substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.