GB2516039A - Security Lighting - Google Patents

Abstract

A device for providing variable diffusion of infra-red and white light for a panning or zooming video camera has a waterproof enclosure comprising a heat dissipating back 1, an array of LEDs 2 and a power management PCB 3. A polycarbonate front cover 5 has a central circular hole providing a waterproof rotary link 6 to control the mechanism. The mechanism comprises two or more clear revolving discs 7, 8, one with gear teeth around its entire circumference and the other with gear teeth around only a part of its circumference. Linking the discs is a gear wheel 9 which may be electrically driven. Movement between the discs is limited to a fraction of a turn via mechanical stops 10. Each disc may carry a diffuser 11 to modify the light output.

Description

Draft Patent Application.

Security Lighting.

This invention relates to a device producing variable diffusion of infra-red and white light.

Security video and area lighting, both Infra-red and white-light, use LED's and lenses to project light into the area covered by the field of view of the camera.

Different applications require light beams with different angular spreads.

The ideal is to project a rectangular beam with wider horizontal spread and a narrow vertical spread to match the camera frame.

Projecting light over a great distance calls for a narrow beam to maximise the intensity.

At close range, a wider beam angle gives an appropriate lower intensity.

Surveillance video that zooms requires lighting that can dynamically change to achieve the best lighting for optimum image quality at different ranges.

This invention provides a variable diffusion mechanism able to change the light projection by rotating discs of diffusing material to one of a number of pre-defined positions to fit the requirements of a zooming video camera lens.

For dynamic video the mechanism is motor driven and synchronized with the camera zoom lens.

The same mechanism operated manually provides a compact light unit with the facility to switch between different light patterns without compromising the waterproof enclosure.

This is an advantage because the manufacturers seal remains intact and only one unit type need be stocked instead of the normal four or five variants to achieve the same range.

Each selectable light pattern provides the optimum horizontal rectangular projection for the camera lens framing.

To compound these advantages, the units link together to create larger arrays and they daisy chain electrically for fast, simple installation.

The invention will now be described solely by way of example and with reference to the accompanying drawings in which: Figure 1 shows an exploded unit with two rotating discs in front of a LED array, and enclosed by a waterproof casing.

Figure 2 shows a lighting unit with a manual adjustment point on the front face and cooling fins and connectors on the rear, Figure 3 showing side and sectional side views of the rotating discs in place.

In figure 1, the unit comprises a waterproof enclosure the rear of which is a heat dissipating aluminium die-casting (01).

Fitted inside the aluminium back is an array of twelve (between 6 and 24) LED's (02) and a power management PCB (03).

Sealing to the front of the aluminium back by means of a rubber seal (04) is a polycarbonate front cover (05) with a central circular hole providing a waterproof rotary link (06) to control the mechanism within.

The enclosed mechanism comprises two or more clear, revolving discs, one with gear teeth around its entire circumference (07), the other(s) with gear teeth around all but one segment of the circumference (08).

Linking the discs movements is a small gear wheel (09) which may be electrically driven.

Movement between the discs is limited to one segment of a revolution using mechanical stops (10).

The size of the array and the proportion of the diffuser disc it will fit behind determines the number of disc subdivisions/segments; two, three, four or more.

The result is a mechanism able to put more different segments in front of the light source than would be physically possible with a single disc system.

With more or less segments of a different angle the discs would give the same advantage over a single disc, ie more diffuser settings than one disc could offer.

In the case of only three diffusing patterns being required and the LED array able to fit behind one third of a disc, only a single disc would be necessary.

Each disc has two, three (or more) equal radial segments, each big enough to carry a light modifying diffuser (11) or moulded diffusing lens big enough to cover the front of the LED array (12).

Holographic diffuser film or moulded diffusing lenses (11) are applied to certain, but not all of the segments so that as the discs revolve the various diffusers modify the light output.

Each diffuser will give different horizontal and vertical angles of light projection in a rectangular or elliptical pattern to maximize illumination at different distances.

The primary, secondary or a third disc can be at the front or the back of the product.

Claims (10)

1. CLAIMS: Referring to figure 1 1. A lighting system wherein two or more revolving discs with light diffusing areas interact mechanically across the front of an array of LED'S to provide a range of rectangular or elliptical light diffusing patterns not achievable with one diffuser or a single disc of diffusers.
2. 2. A lighting system according to claim 1, wherein the primary disc (7) can rotate a sub-division of a full rotation from its start position before linking with a secondary disc (8) through a small linking gear wheel (9), the two linked wheels then rotate together through two or more further segments.The linked discs rotate in either direction to place the different diffusing segments in front of the LED array.Provided that at least one segment on each disc is clear, without a diffuser, the mechanism provides one more segment/diffusion setting than is possible with one disc.
3. 3. A lighting system according to claim 1, wherein the revolving discs interact mechanically by means of a small linking gear wheel meshing with gear teeth on the disc edges or surfaces.
4. 4. A lighting system according to claim 1, wherein the linking cog (9) can be electrically driven to act on and mechanically link the revolving discs (7+8).
5. 5, A lighting system according to claim 1, wherein the electrically driven discs positions are monitored and governed by the electronics using microswitches or a means of optical detection.
6. 6. A lighting system according to claim 1, wherein the primary disc (7) is rotated manually, driving a free-rotating linking cog (9) to selectively rotate the secondary disc (8).
7. 7. A lighting system according to claim 1, wherein the primary disc (7) can be rotated manually with a sealed shaft or key through the front cover.
8. 8. A lighting system according to claim 1, wherein the revolving discs (7+8) are divided into segments to which different value diffusing films can be fitted or have diffusion lenses integrally moulded.Each diffuser will give different horizontal and vertical angles of Fight projection in a rectangular or elliptical pattern to match the camera field of view and maximize illumination at any distance.
9. 9. A lighting system according to claim 1, wherein the lighting unit is linked by daisy-chain electrical connection to an array of units, allowing simultaneous adjustment of the diffusion settings and a simplifying and speeding up of any installation.
10. 10. A lighting system according to claim 1 wherein one lighting unit is linked to another with a linking plate to build an array of units which act as a single, significantly brighter light source.