GB2339920A

GB2339920A - Light filters

Info

Publication number: GB2339920A
Application number: GB9812532A
Authority: GB
Inventors: Barry Jeal
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-06-10
Filing date: 1998-06-10
Publication date: 2000-02-09
Anticipated expiration: 2018-06-10
Also published as: GB2339920B; GB9812532D0

Description

2339920 LIGHT FILTERS The present invention relates to light filters, in

particular to filters for torches and other 0

lighting apparatus. The present invention is particularly related to torches used in 5 night-time hunting - a pursuit known as lamping, but will also find application in other fields, such as filters for lights in the photographic and film industries.

When hunting animals under cover of darkness, obviously the hunter needs to be able to see his quarry. Conventionally, he uses a high power torch. However, to avoid startling the animal a coloured filter is placed in front of the torch lens. Colours found to be useful include shades of red, blue, green and orange.

Filters present a problem ho%%-e,.,er in that they greatly reduce the intensity of the light to the extent that clear definition of the quarry is impossible beyond around 80 yards (75 metres). As it -is -important to distinguish between suitable quarry and the neighbour's pet cat, hunters Will usually remove the filter to provide a clear view of the quarry. Conventional filters clip resiliently, so as not to fall off in use, onto the lens of the torch. Whilst the quarry may be captivated by the filtered fight from the torch, removal of the filter ineVitably results in movement of the torch startling the creature and acting as a warning of human presence.

These difficulties also apply in the photographic and film industries, particularly, in the photographing of animals ai night. Accordingly, there is a need for a light filter system which overcomes these disadvantages in the art, In its broadest sense, the present invention provides a filter which can be mounted upon the lens of a torch, the filter comprising two elements, each element including a fight-filtering portion and a portion which allows unobstructed transmission of light, wherein the first element is rotationally mounted upon the second element such that the degree of filtering can be adjusted between a minimum value and a maximum value.

0 Preferably, each element filters about 50% of the light incident thereupon, such that degree of filtering can be adjusted between 50% and 100%. 50% filtration has been 2 found to provide a good balance between filtered light to entrance the quarry and unfiltered fight to provide the hunter with good clear sight of the quarry.

Suitably, the second element is mountable on the lens of the torch, for example, using 5 adhesive tape.

The above and other aspects of the present invention will now be described in further detail, by way of example only, with reference to the accompanying drawings, in which:

Figure I is a schematic sectional view of a conventional torch of the type used in nighttime hunting; Figure 2 is a side view of the torch of Figure I to which has been fitted an embodiment of a filter in accordance with the present invention-, Figure 3 is a plan view of the rear element of the filter of Figure 2; Figure 4 is a plan view of the front element of the filter of Figure 2; Figure 5 is a plan view showing the filter of Figure 2 in the maximum filtering configuration; and Figure 6 is a plan view showing the filter of Figure 2 in the minimum filtering configuration.

Figure I shows a torch typical of those used in night time hunting and consisting of a high intensity halogen bulb 10 at the centre of a generally parabolic reflector 11 mounted within a casing 12 having a handle 13 and sealed with a front lens 14.

Around the periphery of the lens 14 is a rim 15. It is over this rim that conventional filters are fitted into place. The torch is powered by any suitable means, such as a 12v battery (not shown) and is activated by means of a switch 16 at the rear of the torch.

3 Referring to Figures 2 to 7, the embodiment of the filter shown includes a rear filter element 20 and a front filter element 21 mounted for rotation thereon, by means of a bolt 22 and nut (not shown) engaging central holes in the front and rear filter elements.

The front filter element includes a small handle 2') to assist in adjustment of the filter.

The filter can be secured to the rim 15 of the torch by any suitable means, For example, the rear filter may include a rearwardly projecting rim which engages the rim of the torch in a similar manner to the prior art filters. However, as shown, the filter can be secured simply by means of adhesive tape, such as electrical insulation tape 24. For this reason, front element 21 is typically of slightly smaller diameter than rear element 20.

The front and rear filter elements 20,21 can be made from any suitable coloured, transparent or translucent material, typically a plastics material. Typically, both elements will be made of the same coloured material, but this is not essential.

As is more clearly shown in Figure 3, the rear element 20 includes a number of apertures 30 which allow transmission of fight from the torch bulb 10. There are corresponding apertures 31 in front element 21. The apertures 30,31 can be of any shape and configuration. However, in the preferred embodiment shown, each element has three apertures which each have the appearance of segments of a grapefi-uit cut in half spaced alternately around each filter element. The result is that the front element 21 can be rotated with respect to the rear element such that the apertures in the front element 21 can be adjusted to correspond to those in the rear filter element 20 giving a minimum level of filtering (as shown in Figure 6) or adjusted to lie between the apertures in the rear element 20 giving a maximum (100%) degree of filtering (Figure 5).

As shown, in the preferred embodiment, the rear element 20 includes a rotation stop in the form of a pin 40 projecting forwardly therefrom. The rotation stop pin 40 engages an arcuate slot 41 provided in the front filter element 21. The pin 40 and arcuate slot 41 are positioned in their respective elements such that when the pin is at one end of the slot, the filter is in the maximum filtering position and when the pin is at the other 4 end of the slot, the filter is in the Mmimium filtering position. In the embodiment shown, the front filter 21 is restricted to move only within a 60' range with respect to the rear filter element. This feature allows the hunter to easily adjust the degree of filtration without having to look at the front of the lamp ' to determine the respective overlap of the filter elements - which could result in additional movement of the lamp which may scare the quarry.

It will be immediately apparent that many variations of the features of the embodiment described above will be possible whilst achieving the same effect and are therefore 10 encompassed within the present invention.

CLADIS 1. A light filter comprising two elements, each element including a light- filtering portion and a portion which allows unobstructed transmission of light, wherein the first element is mounted for rotation upon the second element such that the degree of filtering is Austable between a maximum value and a minimum value.

Claims

2. A light filter as claimed in Claim 1 wherein each element filters about

50% of the light incident thereupon.

3. A torch having a light filter as claimed in Claim I or Claim 2. 4. A light filter substantially as herein described with reference to Figures 2 to 6. 15 5. A torch having a light filter substantially as herein described with reference to Figures 2 to 6.