GB2586468A

GB2586468A - Low profile interior light

Info

Publication number: GB2586468A
Application number: GB1911854.6A
Authority: GB
Inventors: Morewood David
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-08-19
Filing date: 2019-08-19
Publication date: 2021-02-24
Anticipated expiration: 2039-08-19
Also published as: GB201911854D0; GB2586468B

Abstract

The circular lighting unit has a housing 1, a diffuser 2, a reflector 20 and LEDs 31 mounted on a circuit board 30. The reflector 20 includes reflective elements 22 arranged around a central hub 23. The reflective elements are sectors of a circle separated by ridges 24 which extend radially outwards from the hub. Each reflective element has a concave head portion 25 and a tail portion 26 which extends towards the hub. Each LED 31 is covered by a convex lens 32 which projects through an aperture 27 in the head portion 25 of the associated reflective element.

Description

LOW PROFILE INTERIOR LIGHT

TECHNICAL FIELD OF THE INVENTION

This invention relates to low profile lighting units, particularly interior lights for vehicles.

BACKGROUND

Interior lights for vehicles are generally mounted above the cab or passenger compartment. They are generally used at night, or under low ambient light conditions, for example to enable a map or delivery instructions to be read when the vehicle is stationary. With conventional lights and reflectors the highest light intensity is achieved immediately below the unit, and rapidly decreases as the angle increases. Ideally the light needs to be spread evenly over a much broader area. On the other hand, it is undesirable for the light pattern to extend horizontally at an angle greater than about 70 degrees from vertical to prevent dazzling other road users. One ideal pattern is generally referred to as a "batwing" light distribution.

Particularly in smaller vehicles, it is desirable that an interior light -2 -has a low profile, especially if it is surface mounted, although this is also desirable for lights which are recessed into a ceiling panel for example.

The present invention seeks to provide a new and inventive form of lighting unit which is of low profile, and provides a more uniform light distribution over the required area without being concentrated in one small region.

SUMMARY OF THE INVENTION

When viewed from one aspect the present invention proposes lighting unit: - a housing; - a diffuser; - a reflector behind the diffuser; - a plurality of LEDs; wherein the reflector includes reflective elements arranged around a central hub, with a respective LED associated with each reflective element, and wherein each reflective element comprises a concave head portion arranged to receive light from the respective LED and a tail portion which extends towards the hub.

In a preferred embodiment the reflective elements are sectors of a circle separated by ridges which extend radially outwards from the hub. -3 -

In a preferred embodiment the LEDs are mounted on a carrier board in registration with an aperture in the concave head portion of each reflective element.

In a preferred embodiment each LED has a lens which projects through the respective aperture.

In a preferred embodiment the housing, the reflector and the diffuser are generally circular.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice. In the drawings: Figure 1 is a general view of a surface-mount lighting unit for a vehicle; Figure 2 is a top plan view of the surface-mount lighting unit; Figure 3 is a side view of the surface-mount lighting unit as seen from the left in Fig.2; Figure 4 is a bottom view of the surface-mount lighting -4 -unit; Figure 5 is a diametrical section A-A through the surface-mount lighting unit as indicated in Fig. 2; Figure 6 is a diametrical section B-B through the surface-mount lighting unit as indicated in Fig. 2; Figure 7 is a general view of the reflector included in the surface-mount lighting unit; Figure 8 shows the light intensity pattern of the surface-mount lighting unit; Figure 9a is a graph showing the photometric distribution of the surface-mount lighting unit; Figure 9b is a graph showing the photometric distribution of an equivalent lighting unit with a conventional reflector; Figure 10 is a general view of a recess-mount lighting unit for a vehicle; Figure 11 is a top plan view of the recess-mount lighting unit; Figure 12 is a side view of the recess-mount lighting -5 -unit; Figure 13 is a bottom view of the recess-mount lighting unit; Figure 14 is a diametrical section C-C through the recess-mount lighting unit as indicated in Fig. 11.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring firstly to Fig.s 1 to 4, a surface-mount interior lighting unit for motor vehicles includes a circular housing 1 having a circular light diffuser 2. As can be seen in the sectional view of Fig. 5, the housing 1 has a rear wall 3 which is surrounded by a side wall 4 having an outward step 7 which divides the side wall into upper and lower wall portions 5 and 6. The upper end of the side wall 4 joins an outer ring 8 which is inclined such that the outer edge 9 meets the back plane P of the rear wall 3. The outer ring 8 incorporates four equally-spaced radially-projecting limbs 10-13 (Fig.s 1 and 2) which are inclined at a shallower angle to meet the plane P further out from the edge 9 as seen in the sectional view of Fig. 6. Two of the limbs, 11 and 13, contain recessed fixing holes 14 which can be used to fix the lighting unit to a surface using screws. Returning to Fig. 5, the diffuser 2 has a shallow domed portion 16, continuing the curve of the ring 8, surrounded by a cylindrical edge wall 17 which is retained against the step 7 within the upper wall portion 5 by a snap fit, frictional -6 -engagement, or permanent bonding, etc. It will be appreciated that the lighting unit is of very low profile, typically having a maximum depth D of less than 15 mm between the centre of the diffuser 2 and the back of the rear wall 3 (see Fig. 3).

Continuing with Fig.s 5, the housing 1 contains a disc-shaped reflector 20 with a short lip 21 which locates against the step 7 within the edge wall 17 of the diffuser 2. A disc-shaped printed circuit board 30 is mounted behind the reflector 20 against the rear wall 3, the board being located within the lower wall portion 6 and secured by screws 40 inserted through the rear wall 3 (Fig. 4).

The reflector 20, which is also shown separately in Fig. 7, includes a number of reflective elements 22 (e.g. twelve) forming equal sectors of a circle arranged around a central hub 23, which is formed by a part-conical depression in the centre of the reflector. The reflective elements 22 are separated by ridges 24 which extend radially outwards from the hub. Each reflective element comprises a concave head portion 25 and a tail portion 26 which extends towards the hub. Returning to Fig. 5, The board 30 carries twelve LEDs (light emitting diodes) 31, which are each covered by a convex lens 32. Electrical power may be supplied to the LEDs via wires W passing through the step 7 in the side wall 4 (Fig. 4). The lenses project through apertures 27 positioned at the lowest part of the reflective elements 22 within the concave head portion 25, so that each reflective element receives light from a respective LED. -7 -

Fig. 8 shows the light intensity pattern of the lighting unit as viewed through the diffuser 2, and Fig. 9a shows the photometric light distribution on a random plane diametrically of the lighting unit. It will be noted that Fig. 9a exhibits a typical batwing distribution pattern with the light spread through a wide angle with very little light emitted at angles greater then about 70 degrees. Contrast this with a typical pattern in Fig. 9b for lights with conventional reflectors and of much deeper profile. This distribution pattern shows that the light is concentrated in a relatively small high intensity area directly beneath the unit.

Fig.s 10-14 show another embodiment of an interior lighting unit for motor vehicles which can be mounted in a hole or recess in a ceiling panel. This lighting unit includes a circular housing 101 having a circular light diffuser 102. As can be seen in the sectional view of Fig. 14, the housing 101 has a rear wall 103 which is surrounded by a side wall 104 having an outward step 107 which divides the side wall into upper and lower wall portions 105 and 106. The upper end of the side wall 104 joins an annular outer ring 108 (Fig. 10) which projects radially outwards. The ring 108 incorporates four equally-spaced radially-projecting limbs 110-113. Two of the limbs, 111 and 113, contain fixing holes 114 which can be used to fix the lighting unit using screws. The diffuser 102 has a shallow domed portion 116 (Fig. 14) surrounded by a cylindrical edge wall 117 which is retained against the step 107 within the upper wall portion 105 by a snap fit, frictional engagement, or permanent bonding, etc. The domed -8 -portion 116 may be slightly recessed below the outer ring 108. The lighting unit is of very low profile, typically having a maximum depth D of less than 15 mm between the top of the ring 108 and the back of the rear wall 103 (Fig. 12).

Continuing with Fig. 14, the housing 101 contains a disc-shaped reflector 20 as described above in relation to Fig. 7. The lip 21 locates against the step 107 within the edge wall 117 of the diffuser 102. A disc-shaped printed circuit board 130 is mounted behind the reflector 120 against the rear wall 103, the board being located within the lower wall portion 106 and secured by screws 140 inserted through the rear wall 103 (see Fig. 13).

The printed circuit board 130 carries twelve LEDs 131, which are each covered by a convex lens 132. Electrical power may be supplied to the LEDs via wires W passing through the step 107 in the side wall 104 of the housing 101 (Fig. 13). The lenses 132 project through the apertures 27 in reflector 20.

The light intensity pattern of the lighting unit as viewed through the diffuser 102 is as illustrated in Fig. 8, and the photometric light distribution is as shown in Fig. 9a. The light distribution again exhibits a typical batwing pattern with the light spread through a wide angle across the lighting unit with very little light emitted at angles greater then about 70 degrees.

Whilst the above description places emphasis on the areas which are believed to be new and addresses specific problems which -9 -have been identified, it is intended that the features disclosed herein may be used in any combination which is capable of providing a new and useful advance in the art.

Claims

-10 -CLAIMS1. A lighting unit: - a housing; - a diffuser; - a reflector behind the diffuser; - a plurality of LEDs; wherein the reflector includes reflective elements arranged around a central hub, with a respective LED associated with each reflective element, and wherein each reflective element comprises a concave head portion arranged to receive light from the respective LED and a tail portion which extends towards the hub.
2. A lighting unit according to claim 1 in which the reflective elements are sectors of a circle separated by ridges which extend radially outwards from the hub.
3. A lighting unit according to claim 1 or 2 in which the LEDs are mounted on a carrier board in registration with an aperture in the concave head portion of each reflective element.
4. A lighting unit according to claim 3 in which each LED has a lens which projects through the respective aperture.
5. A lighting unit according to any preceding claim in which the housing, the reflector and the diffuser are generally circular.