GB2336426A - Adjustable lamp - Google Patents

Abstract

An adjustable lamp 32 has a lamp housing 10 has a pivotal linkage 18 to a mounting ring 16 of a frame. The pivotal linage comprises two arms 20, 22 which are pivotally attached to the frame with a short distance between the two pivot points 24, 28 and pivotally attached to the housing with a larger distance between the two pivot points 26, 30. The two arms are also of different lengths which combined with the attachment arrangement causes the lamp housing to pivot through a curve such that the housing may be constructed to have greater height than width and still pass through a circular opening.

Description

2336426 Adjustable Lamip The n--esent invention relates to an adjustable

lamp and in t particular to the type of adjustable lamp typically mounted in a ceiling and known as a downlighter.

2 C Downl-1.ghters are known, and generally comprise a lamp held within a reflector housing, which itself is pivotably mounted in a frame. The frame is then fixed within an aperture in a ceiling. The pivotable mounting allows the position of the reflector housing to be adjusted to direct a beam of light in the desired direction.

A known downlighter has a simple pivot mechanism to allow the direction of the beam to be varied, and a housing of part spherical shape mounted in a frame in the form of a surface mounting ring. The radius of curvature of the housing is limited to that which can be accommodated within the surface mounting ring. The use of a reflector housing of part spherical shape allows a sufficient range of pivoting movement of the lamp of around 55' from its usual:)osition (the beam directed straight down).

We have appreciated that the part spherical shape discussed above results in a number of drawbacks. The housing is generally a quadrant of a sphere and, as such, has a limited depth of reflector resulting in high glare levels, characterless undifferentiated performance and a risk of excessive lamp temperatures because of inadequate enclosure space. It is therefore preferred to use a reflector of more generally parabolic cross section to alleviate these problems.

we have also appreciated that the use of a parabolic reflector requires a reflector housing of greater depth, and that this would restrict the angle of movement of the housing when used with known mountings.

In a broad aspect, the invention provides an adjustable lamp with an improved pivot mechanism, and which overcomes the problems noted above.

in particular, the invention provides an adjustable lamp having a housing holding a bulb and which is pivotably mounted in an aperture of a frame and a pivot mechanism linking the housing and the frame which is so arranged that the housing is pivotable through the aperture through an arc of varying curvature.

i 0 The use of a pivot mechanism which provides such a varying curvature of arc, allows a reflector housing of greater depth to be used, 'M comparison to known part spherical housings, but without impeding the angular range through which the housing may be adjusted.

In a preferred embodiment, therefore, the housing has a depth greater than the diameter of the aperture of the .a tage that the reflector may This provides the advanhave a more generally parabolic cross-section, rather than a hemi-spherical cross-section, and has improved reflective and lamp shielding properties.

in the preferred embodiment, the pivot mechanism comorises at least one arm pivotably attached to each of the frame and the housing. This provides a spacing between the frame and the housing ensuring that the housing is not impeded by the f rame.

in the preferred embodiment, there are two such pivotably mounted arms to provide the varying curvature of the arc. In the embodlment, these two arms are mounted at pivot points spaced frornn one another on the housing and on the frame, and the arms are of different lengths to one another. These -features provide the varying curvature of arc movement.

3 An embodiment of the invention will now be desc-ribed, by way of example only and with reference to the figures in which:

r Figure 1 is a cross sectional view of an adjustable lamp embodying the invention; and Figures 2-5 show the lamp of figure 1 in various positions of movement through an arc.

The adjustable lamp shownin figure 1 comprises a reflector housing 10 which houses a reflector 12 and a bulb 14 which is attached to the housing 10 and is positioned within the reflector 12. The housing is pivotably mounted within a frame in the form of a mounting ring 16. The bulb 14 is attached to a bulb block 15 which itself is attached to the housing 10, thus securing the bulb with respect to the housing and with respect to the reflector 12.

A pivot mechanism 18 links the housing 10 to the mounting ring 16, and comprises a first arm 20 and a second arm 22 each being pivotably mounted at either end therof to the housing and frame respectively. The first arm 20 is pivotably attached at a first pivot point 24 on the mounting ring, and at a second pivot point 26 on the housing 10. Similarly, the second arm 22 is attached at a third pivot point 28 on the mounting ring, and at a fourth pivot point 30 on the housing. The second arm 22 longer than the first arm 20, and the spacing of the first and third pivot points on the frame is smaller than the spacing of the second and fourth pivot points on the housing. This atrangement provides the varying curvature of arc as the housing is pivoted through an aperture 32 of the mounting ring 16.

The pivoting of the housing within the mounting ring is shown in figures 2 to 5. As can be seen, the pivot mechanism with double linkeage provided by --he first and second arms 20,22 provides a pivoting action of the lamp housing (and hence the direction of the light beam) such that the the housing passes through a locus of points with an arc which has a varying curvature as the housing is moved.

is The arc corresponds to +the curvature of the cross section of the rear surface 38 of the housing 10. The curvature of the arc increases as the housing is pivoted further within the mounting ring. The rear surface 38 of the housing may thus have a curvature which increases with height, allowing a housing shape which has a greater ieight than the d'ameter of the aperture 32 through which it casses.

The embodiment of the invention thus allows a mounting ring with an aperture of given diameter to be used with a reflector housing of heightwhich is greater than the aperture diameter.

The adjustable lamp has a small footprint requirement in the hole required in the ceiling within which the mounting ring is fixed, whilst providing low glare levels, low heat build up in the relatively large cavity 13 between the reflector and refelector housing. The rear surface 38 of the housing is also chosen to have a curvature corresponding to the locus of movement of the whole housing, and a circular cross section, so that the housing maintains a close fit to the inner edge of the mounting ring 16 defining the aperture 32.

The embodiment of the invention allows a choice of bulb to be used, including Tungsten Halogen, Discharge or PL Comnact Fluorescent bulbs. This is because of the improved shape of the housing which has more space available than known downlighters, and can therefore accept larger lamps without risk of heat build up.

The adjustable lamp described above may be fitted as a downlighter by fitting the perimeter wall 34 of the mounting ring 16 in a hole in a ceiling with the annular flange 36 fitted against the ceiling. Of course, the skilled person would appreciate that the embodying lamp could also be fitted in other ways, and such uses are within the scope of the invention.

other features could also be varied within the scope of the invention. The housing and reflector have been described as separate units, however, it would be possible to make these as a single unit, or to make the housing tself reflective.

Claims (8)

Claims

1. An adjustable lamp having a housing holding a bulb and which is pivotably mounted in an aperture of a frame, and a pivot mechanism linking the housing and the frame which is so arranged that the housing is pivotable through the aperture through an arc of varying curvature.

2. An adjustable lamp according to claim 1, wherein the the curvatu--e of the arc increases with the angle of pivoting of the housing.

3. An adjustable lamp according to claim 1 or 2, wherein the housing has a depth greater than the diameter of the aperture of the -frame.

4. An adjustable lamp according to claim 1, 2 or 3, wherein the pivo-mechanism comprises at least one arm pivotably attached to each of the frame and the housing.

5. An adjustable lamp according to any preceding claim, wherein the pivot mechanism comprises a first arm and a second arm, each arm being pivotably attached to the housing and to the frame.

6. An adjustable lamp according to claim 5, wherein the second arm is longer than the first arm.

l L

7. An adjustable lame according to claim 5 or 6, wherein the first and second arms are attached at pivot points wth a first se:)aratJon on the frame, and attached at pivot points with a second longer separation on the housing.

8. An adjustable lamp substantially as herein described and wit'n reference to the accompanying figures.