GB2197518A

GB2197518A - Visual display system

Info

Publication number: GB2197518A
Application number: GB08623257A
Authority: GB
Inventors: Kenneth Winstanley
Original assignee: Airship Industries UK Ltd
Current assignee: Airship Industries UK Ltd
Priority date: 1986-09-26
Filing date: 1986-09-26
Publication date: 1988-05-18
Also published as: JPS6385796A; GB8623257D0

Abstract

A visual display system for mounting on the outside of an airship comprises a matrix (1, 2) of light-emitting diodes, which is fed with video signals from a video tape player (7) and possibly from a manual input keyboard (8). Monitors (12, 13) are provided to enable a person controlling the display to see what is being displayed. The display may be in colour. <IMAGE>

Description

SPECIFICATION Visual display system This invention relates to a visual display sys tem, and particularly to a visual display sys tem adapted to be carried by an airship.

Airships are now often used as mobile ad vertisement hoardings, since when in flight they offer a large surface area which can be seen over a wide area.

According to this invention there is provided a visual display system comprising a matrix of light emitting diodes; a source of video sig nals; and coupling means operative to couple signals from the source to the matrix to pro duce a display thereon.

A visual display system according to this invention will now be described, by way of example, with reference to the drawing which is a block schematic diagram of the display.

The system to be described comprises two signs to be mounted on opposite sides of an airship, and means to produce television type images on the signs.

Referring to the drawing, each sign 1 or 2 comprises a matrix of light emitting diodes formed by ninety six strips of flat flex electrical cable each having mounted thereon forty eight printed circuit boards each providing two matrix points (pixels) formed by nine red and nine green light emitting diodes and associated circuitry, there thus being 9216 such points in each sign. It will be appreciated that other colour, for example blue, light emitting diodes can be included at each matrix point to enable full colour images to be produced, although the use of only red and green diodes has been found to be satisfactory. Diodes of the same colour at each matrix point are connected in series and are driven by a transistor constant current source in the associated cir cuitry.

For use, each sign is attached to an airship by any convenient means, the exposed portions of the electrical cables being covered with shielding material such as aluminium foil to give protection from lightning strikes. The boards carrying the diodes and associated circuitry are covered with varnish to give protection against rain The system is powered by a petrol driven engine which drives a 400 amp 28V aircraft generator 3 the output of which is supplied by way of a distributor arrangement 4 and a fuse arrangement 5 as necessary within the system. In particular, the distributor 4 feeds a DC-DC converter 6 which provides outputs as shown for use within the system.

Images to be displayed on the signs 1 and 2 are derived from a video tape player 7 and also from a manuaily operable caption generator 8 comprising a keyboard of conventional type, having an associated floppy disc drive 9.

The outputs of the player 7 and generator 8 are passed by way of a video mixer 10 to an analogue to digital converter and buffer device 11 which digitises the incoming video signals.

The generator 8 also feeds a first monitor 12 on which an operator can see what he has entered before this is displayed on the signs 1 and 2, while a second monitor 13 fed from the converter 11 gives the opertor a picture of what is being displayed on the signs 1 and 2 at any time.

The output of the converter 11 is passed by way of a digital logic buffer 14 using high speed CMOS integrated circuits, to twelve distributor boards 15 each of which feeds circuitry in twenty four aluminium junction boxes 16 associated with the two signs 1 and 2, respectively, whereby the signs 1 and 2 received identical signals for display. The buffer 14 also generates timing information from the received signals and passes this to the distributor boards 15. An EPROM based circuit in the buffer 14 calculates the intensity of the video image in the received signal, on a frame by frame basis and passes this information to the distributor boards 1 5. Each distributor board 15 carries a microprocessor and associated integrated circuits containing software for the microprocessor.

Each junction box 16 contains a passive connector card which serves to provide power and signal connections to the diode arrays, and to a further card in the box carrying a microprocessor and integrated circuits containing software for the microprocessor. In response to the received signals the microprocessor provides signals for driving eight strips of diode arrays (768 pixels) served by that junction box 16. Also contained in each junction box 16 is a switched-mode power supply which provides the power for the associated transistor constant current sources driving the associated diodes, input power being drived from the fuse arrangement 5 as shown.

The system described above operates to reproduce the images from a tape played on the player 7, possibly supplemented by input from the generator 8, on the signs 1 and 2, using raster scan techniques at 25 frames per second for image generation. With the diodes provided, sixteen major colours with over four thousand shades are possible, giving colour resolution comparable to that of a domestic television set.

The system is arranged in four parts, namely the signs, an electronics assembly, a control assembly, and the power supply generator.

The signs provide a 100 mm x 100 mm matrix of pixels. They can be attached to an airship in any convenient manner, for example by adhesive means, with the cabling covered with aluminium foil as protection against lightning strikes, the foil being connected to the airship's standard lightning protection cage.

The electronics assembly is housed in an aluminium housing adapted to be carried under the airship's gondola, the housing being formed to prevent RFI emmission therefrom.

All signals into and out of the housing are filtered for the same reason. The housing contains one or more fans which serve to prevent overheating.

The control assembly is of aluminium construction and is in modular form for ease of assembly and removal from an airship. This assembly comprises units 6 to 13 shown in the drawing.

The power supply generator is housed in a titanium housing adapted to be carried under the gondola of the airship in detachable manner.

Claims

1. A visual display system comprising a matrix of light emitting diodes; a source of video signals; and coupling means operative to couple signals from the source to the matrix to produce a display thereon.

2. A system as claimed in Claim 1, in which each matrix point is formed by at least two diodes emitting mutually different colour light.

3. A system as claimed in Claim 1 or Claim 2, in which the source comprises a tape player.

4. A system as claimed in any preceding claim, in which the source includes manually operative input means.

5. A system as claimed in any preceding claim, including a monitor showing the display produced on the matrix.

6. A system as claimed in Claim 5 as dependent upon Claim 4, including a second monitor showing the input entered by the input means prior to display on the matrix.

7. A visual display system substantially as hereinbefore described with reference to the drawing.