EP0849523A2

EP0849523A2 - Vehicle lamp

Info

Publication number: EP0849523A2
Application number: EP97309941A
Authority: EP
Inventors: Francis Thompson
Original assignee: Britax Vega Ltd; Koito Europe Ltd
Current assignee: Koito Europe Ltd
Priority date: 1996-12-21
Filing date: 1997-12-10
Publication date: 1998-06-24
Also published as: GB9626638D0; EP0849523A3; JPH10188605A; KR19980064217A

Abstract

A vehicle lamp for mounting near a corner of a vehicle so as to be visible over a wide angular range, comprises a reflector (50) with a substantially paraboloidal main zone (52) and a side zone (58) comprising a series of paraboloidal segments (60) having the same focus and axis as the paraboloid of the main zone (52) with a respective step (62) between each pair of adjacent segments. characterised in that only one segment (60) is separated from the main zone (52) by a single step (62), and in that the steps (62) between each pair of adjacent segments are substantially straight and substantially parallel to one another.

Description

This invention relates to a vehicle lamp for mounting near a corner of a vehicle so as to be visible over a wide angular range, of the type comprising a reflector with a substantially paraboloidal main zone and a side zone comprising a series of paraboloidal segments having the same focus and axis as the paraboloid of the main zone with a respective step between each pair of adjacent segments.

Lamps of this type are commonly used as turn signal lamps. Such lamps are required to display a relatively bright light in directions generally parallel to the direction of motion of the vehicle, so as to be visible to drivers of other vehicles from a substantial distance. They are also required to be visible from the side of the vehicle, although a lower brightness is acceptable in this direction. In order to obtain the required brightness in directions parallel to the direction of travel, it is preferable for such a lamp to have a paraboloidal reflector. In order to obtain the required visibility from the side of the vehicle, it is necessary to cut away part of the paraboloidal reflector to allow light to reach the side of the lamp directly from the bulb. To avoid wasting the light which would then fall on the back of the lamp housing, it has been customary to provide faceted reflector surfaces in this region for directing light in the same general direction as the main paraboloid. It is an object of the invention to provide a vehicle light of this type in which the resulting discontinuities in the reflector surface do not produce readily perceptible changes in brightness between adjacent parts of the exterior surface of the lamp.

According to the invention, in a vehicle lamp of the type described above, only one paraboloidal segment is separated from the main zone by a single step, and the steps between each pair of adjacent segments are substantially straight and substantially parallel to one another.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a lamp assembly for the rear left hand corner of a motor car;

Figure 2 is an elevational view, from the rear of the motor car, of a turn signal indicator lamp forming part of the cluster shown in Figure 1, with the lens removed;

Figure 3 is a perspective view of the reflector and bulb of the lamp shown in Figure 2;

Figure 4 is a cross-sectional view taken on the line 4-4 in Figure 2;

Figure 5 is an elevational view, similar to Figure 2, of a lamp in accordance with the invention;

Figure 6 is a perspective view of the reflector and bulb of the lamp shown in Figure 5; and

Figure 7 is a sectional view taken on the line 7-7 in Figure 5.

Figure 1 shows a lamp assembly 10 comprising a left-hand rear lamp cluster for a motor car. The assembly 10 includes a first lens 12 for a turn signal indicator, a second lens 14 for a reversing lamp, a third lens 16 for a stop/tail lamp, a reflex reflector 18,and a fourth lens 20 for a rear fog lamp. The present invention is concerned with the reflector for the turn signal indicator behind the lens 12.

Figures 2, 3 and 4 show a known reflector and bulb assembly for fitting behind the lens 12 of Figure 1. The reflector 30 has a paraboloidal main zone 32 containing a hole 34 behind which is a bulb holder (not shown) for a bulb 36. To ensure that the reflector 30 gives the required width of beam on the left-hand side of the vehicle, the corresponding part of the main zone 32 is cut away and replaced by a side zone 38 comprising a series of annular paraboloidal segments such as the segment 40, separated from adjacent segments by steps such as the step 42.

As can best be seen from Figures 3 and 4, the bottom of the side zone 38 is separated from the adjacent part of the main zone 32 by a wall 44 of generally triangular shape. The effect of this is that the path length of light from the filament of the bulb 36 to the lens 12 (Figure 1) via the main zone 32 is substantially less than that reaching an immediately adjacent part of the lens 12 via the outer segments of the side zone 38. The result of this is that there is a significant change in the brightness of the lens along a line corresponding to the wall 44. A similar effect occurs at the upper edge of the zone 38, although this is somewhat mitigated because the tapering shape of the lens 12 in this region provides room for intermediate paraboloidal segments 46.

Figures 5, 6 and 7 illustrate a reflector and bulb assembly in accordance with the invention which gives a more uniform appearance to the distribution of light over the lens 12. The reflector 50 has a paraboloidal main zone 52 containing a hole 54 behind which is accommodated a bulb holder (not shown) for a bulb 56.

The reflector 50 also has a left-hand side zone 58 comprising a series of paraboloidal segments having the same focus and axis as the paraboloid of the main zone 52. For example, the segment 60 is separated from an adjacent segment by the step 62. Instead of being annular, the shape of the segments is chosen to be such that there is only one segment 64 which is separated from the main zone 52 by a single step 66. For best performance from the reflector itself, the steps are straight and parallel to one another. However, for best overall performance, it is preferable for the steps to be aligned with the substantially vertical lines between adjacent optical elements on the lens 12 (Figure 1) provided that the steps are substantially straight and substantially parallel to one another.

The result is that the maximum change in path length of light from the filament of the bulb 56 to adjacent parts of the lens 12 is determined by the height of the steps such as the

steps

62 and 66. Consequently, there is no sudden change in the brightness of adjacent parts of the lens, the changes due to light from successive segments being imperceptible to the eye.

Claims

A vehicle lamp for mounting near a corner of a vehicle so as to be visible over a wide angular range, comprising a reflector (50) with a substantially paraboloidal main zone (52) and a side zone (58) comprising a series of paraboloidal segments (60) having the same focus and axis as the paraboloid of the main zone (52) with a respective step (62) between each pair of adjacent segments, characterised in that only one segment (60) is separated from the main zone (52) by a single step (62), and in that the steps (62) between each pair of adjacent segments are substantially straight and substantially parallel to one another.
A vehicle lamp according to claim 1, further comprising a lens (12) having a substantially rectangular array of lens elements, aligned so that transitions in light levels incident thereon due to said steps (62) are coincident with gaps between adjacent rows of lens elements.