GB1604874A - Approach slope indicators - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO APPROACH SLOPE INDICATORS (71) I, SECRETARY OF STATE FOR DE FENCE, London, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to approach slope indicator units for airfields.

In particular the present invention is a modification of the approach slope indicator disclosed in the complete specification of United Patent Application No 40062/76 (Serial No 1597704).

According to the present invention an approach slope indicator unit comprises a rigid container having a lid securable thereto and at least two pre-alignable projectors each adapted to produce a split beam of light, each projector being in the form of a single module independently housed within the container and removable in total therefrom, the container having a front wall adapted to transmit a projected beam of light from each projector.

A pre-alignable projector when used in the indicator unit may comprise: a light source, a red-passing filter and a divergent lens coaxially combined to produce a divergent beam, one half of which is white light the other half of which is red light.

Preferably the pre-alignable projector has the light source and the divergent lens mounted on separate sub-frames, the subframes being rigidly linked by at least three connecting rods. The red-passing filter may be housed in a carrier bracket which is slidably adjustable on at least two of the connecting rods and which is adapted to be clamped in position when the red-passing filter is at the focus of the lens. To ensure equal proportions of red and white light the lens may be vertically adjustable with respect to the lens sub-frame.

The light source sub-frame and the lens sub-frame may be provided with jacking screws to adjust the projector to the correct angle of elevation when positioned in the container.

An approach slope indicator unit in accordance with the present invention will now be described by way of example with reference to the accompanying drawings of which: Figure 1 shows a plan view of the ap proach slope indicator unit with the lid removed, Figure 2 shows a sectional elevation of the approach slope indicator unit shown in Figure 1 on the line I-I, and Figure 3 shows a sectional elevation of the approach slope indicator unit shorn in Figure 1 on the line Il-Il.

An approach slope indicator unit as shown in Figures 1, 2 and 3 comprises a rigid container 10 having a removable lid 11, which houses two pre-alignable projectors 12.

The container 10 has two circular cut-outs 13 in its front wall 14, each cut-out surrounded by a cylindrical cowl 15. Two bellows members 16 seal the container between the projectors 12 and the cut-outs 13.

The projectors 12 are supported upon platform blocks 17 which are fixedly attached to the base of the container 10.

The pre-aligned projector 12 includes a light source sub-frame 18 and a lens subframe 19, which are rigidly linked by connecting rods 20, 21, 22 and 23. The subframes 18 and 19 each have two jacking screws 24 threaded therein and arranged to rest upon the platform blocks 17. A filter assembly 25 is slidably mounted on the connecting rods.

The light source sub-frame 18 has fixedly mounted thereon a light source 26 which produces a parallel beam of light. A planoconvex lens 27 is fixed to a carrier plate 28 which is vertically adjustable on the lens subframe 19 by means of fixing screws 29.

The filter assembly 25 includes a carrier bracket 30 and a locking screw 31 threaded therein. The carrier bracket is slidable on the connecting rods 20 and 21 and may be locked into a required position by adjusting the clamping screw 31 to clamp the carrier bracket 30 to the connecting rod 20. A redpassing filter 32 is mounted in the carrier bracket 30 and held in position by a leaf spring 33.

Each projector 12 is pre-aligned prior to insertion into the container 10, to emit a divergent beam of light the upper half of which is white and the lower half of which is red, there being a sharp transition between the two halves. This is achieved by adjusting the position of the filter assembly 25 until the red-passing filter 30 is coincident with the focal point of the lens 27. When this position is achieved the filter assembly 25 may be clamped to the connecting rod 20 by means of the clamping screw 31. Further adjustment to obtain equal proportions of red and white light may be achieved by moving the lens 27 and the carrier plate 28 with respect to the lens sub-frame 19. The carrier plate 28 may be locked in the adjusted position by means of fixing screws 29.

After insertion into the container 10 each projector 12 is adjusted to the correct ap proach slope by means ofthejacking scresws 24 and a clinometer, (not shown). When the projectors 12 are correctly adjusted the lid 11 may be replaced and secured to the container 10.

It will be appreciated that the above embodiment is described by way of example and that the invention can be realised in different forms. The cut-outs 13 may include glass windows, the bellows member thereby being dispensed with. A clamping plate may be securably attached to the filter assembly 25 so that the rods 20 and 21 may be clamped between the plate and the filter assembly 25.

In an alternative arrangement the projectors 12 may independently be mounted on a rigid supporting plate, the plate having jacking screws resting upon corresponding platform blocks fixed to the base of the container. In this arrangement the projectors are adjusted to the correct elevation by adjusting the angular position of the supporting plate.

WHAT I CLAIM IS: 1. An approach slope indicator unit comprising a rigid container having a lid securable thereto and at least two pre-alignable projectors each adapted to produce a split beam of light, each projector being in the form of a single module independently housed within the container and removable in total therefrom, the container having a front wall adapted to transmit a projected beam of light from each projector.

2. A pre-alignable projector when used in the indicator unit of claim 1 comprising: a light source, a red-passing filter, and a divergent lens co-axially combined to produce a divergent beam, one half of which is white light the other half of which is red light.

3. A pre-alignable projector as claimed in claim 2 and wherein the light source and the divergent lens are each mounted on separate sub-frames and rigidly linked by at least three connecting rods.

4. A pre-alignable projector as claimed in claim 3 including a carrier bracket housing the red-passing filter, the carrier bracket being slidably adjustable on at least two of the connecting rods and adapted to be clamped in position when the red-passing filter is at the focus of the lens.

5. A pre-alignable projector as claimed in claim 3 or 4 wherein the filter is vertically adjustable with respect to the lens sub-frame 6. A pre-alignable projector as claimed in any one of the claims 2 to 5 and wherein the light source sub-frame and the lens subframe each include jacking screws to adjust the projector to the correct angle of elevation when positioned in the container.

7. A pre-alignable projector as claimed in any one of claims 2 to 5 which is mounted on an angularly adjustable supporting plate and which, in use, is adjusted to the correct angle of elevation by adjusting the angular position of the supporting plate.

8. An approach slope indicator unit substantially as herein before described and with reference to Figures 1, 2 and 3 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. divergent beam of light the upper half of which is white and the lower half of which is red, there being a sharp transition between the two halves. This is achieved by adjusting the position of the filter assembly 25 until the red-passing filter 30 is coincident with the focal point of the lens 27. When this position is achieved the filter assembly 25 may be clamped to the connecting rod 20 by means of the clamping screw 31. Further adjustment to obtain equal proportions of red and white light may be achieved by moving the lens 27 and the carrier plate 28 with respect to the lens sub-frame 19. The carrier plate 28 may be locked in the adjusted position by means of fixing screws 29. After insertion into the container 10 each projector 12 is adjusted to the correct ap proach slope by means ofthejacking scresws 24 and a clinometer, (not shown). When the projectors 12 are correctly adjusted the lid 11 may be replaced and secured to the container 10. It will be appreciated that the above embodiment is described by way of example and that the invention can be realised in different forms. The cut-outs 13 may include glass windows, the bellows member thereby being dispensed with. A clamping plate may be securably attached to the filter assembly 25 so that the rods 20 and 21 may be clamped between the plate and the filter assembly 25. In an alternative arrangement the projectors 12 may independently be mounted on a rigid supporting plate, the plate having jacking screws resting upon corresponding platform blocks fixed to the base of the container. In this arrangement the projectors are adjusted to the correct elevation by adjusting the angular position of the supporting plate. WHAT I CLAIM IS:

1. An approach slope indicator unit comprising a rigid container having a lid securable thereto and at least two pre-alignable projectors each adapted to produce a split beam of light, each projector being in the form of a single module independently housed within the container and removable in total therefrom, the container having a front wall adapted to transmit a projected beam of light from each projector.

2. A pre-alignable projector when used in the indicator unit of claim 1 comprising: a light source, a red-passing filter, and a divergent lens co-axially combined to produce a divergent beam, one half of which is white light the other half of which is red light.

3. A pre-alignable projector as claimed in claim 2 and wherein the light source and the divergent lens are each mounted on separate sub-frames and rigidly linked by at least three connecting rods.

4. A pre-alignable projector as claimed in claim 3 including a carrier bracket housing the red-passing filter, the carrier bracket being slidably adjustable on at least two of the connecting rods and adapted to be clamped in position when the red-passing filter is at the focus of the lens.

5. A pre-alignable projector as claimed in claim 3 or 4 wherein the filter is vertically adjustable with respect to the lens sub-frame

6. A pre-alignable projector as claimed in any one of the claims 2 to 5 and wherein the light source sub-frame and the lens subframe each include jacking screws to adjust the projector to the correct angle of elevation when positioned in the container.

7. A pre-alignable projector as claimed in any one of claims 2 to 5 which is mounted on an angularly adjustable supporting plate and which, in use, is adjusted to the correct angle of elevation by adjusting the angular position of the supporting plate.

8. An approach slope indicator unit substantially as herein before described and with reference to Figures 1, 2 and 3 of the accompanying drawings.