Display system

Abstract

 An image display system comprises a row of images, each image having a respective illumination device. A trigger device is associated with each image. Each trigger device is arranged such that, in use, it detects a marker associated with each window on a train passing its associated image and activates its associated illumination device.

Description

[0001] This invention relates to a display system for displaying images to passengers on a train when the train is passing through a tunnel.

[0002] In recent times there have been various proposals for the use of the walls of railway tunnels or bridges to provide images that form the base of an entertainment or advertising system. Such systems attempt to display a series of still images in turn, creating the illusion of a moving image.

[0003] Such systems have a number of problems, however. The most significant of these is that they are difficult to configure such that they operate for a wide range of varying train speeds. In particular, variations in train speed can result in illumination of the individual images at a rate which is not totally synchronised with the passage of the train, resulting in the passengers viewing a moving image, but one which also appears to wander to the left or to the right as the train slows down or picks up speed. This limits the effectiveness of the display.

[0004] According to the present invention there is provided an image display system comprising:

a row of images, each image having a respective illumination device; and

a trigger device associated with each image, each trigger device arranged such that, in use, it detects a marker associated with each window on a train passing its associated image and activates its associated illumination device.

[0005] With the arrangement of the present invention, because illumination of individual images is only triggered when the image and a window are in exact alignment there is no perceived wandering of images by passengers viewing the illuminated images as the train passes. This ensures, therefore, that the overall display quality is consistent and can be viewed by passengers without problem.

[0006] The illumination device may be a simple flash light which is preferably a Xenon type bulb.

[0007] The images may be held in a row of frames, each of which is arranged to be attached to a wall in use, and each of which may be hinged to allow replacement of the image that it holds to change the sequence of images to be displayed.

[0008] The trigger device may be arranged to be activated by an optical reflector positioned below each window on a train.

[0009] In such a case, the trigger device may contain an optical transmitter and receiver arrangement, triggering the illumination device when transmitted light, which may be from the near infrared part of the electromagnetic spectrum, from the transmitter is received by the receiver from the reflector. The reflector may be arranged such that it does not alter the polarisation of light that it receives, and the trigger device in such a case may transmit polarised light, such that its receiver is only triggered by light of appropriate polarisation in order to prevent erroneous triggering by light transmitted from adjacent trigger devices and illuminating devices.

[0010] One example of the present invention will now be described with reference to the accompanying drawings, in which:

Fig. 1 is a schematic view of a train with reflectors marking the position of its windows;

Fig. 2 is a schematic cross-sectional view of a train passing a part of the system of the invention;

Fig. 3 is a schematic view of a block of image holding frames employed in the invention;

Fig. 4 is a graph showing optimum spacings for adjacent images in relation to varying train speeds and the number of frames required per second;

Fig. 5 shows front, side and perspective views of a frame for retaining images in accordance with the invention; and

Fig. 6 is a schematic diagram showing a trigger mechanism in accordance with the invention.

[0011] Referring to figure 1, a train 1 consists of a series of carriages 2, each of which has windows 3. Each window 3 has a marker 4 positioned below it. In this example, the marker 4 is a simple piece of reflective tape, and may be no bigger than 25mm by 75mm.

[0012] Figure 2 shows the train 1 in a tunnel 5. It also shows a side view of an image holding frame 6 and a trigger device 7 that will be described in more detail below. As can be seen from figure 2, the image holding frame 6 is arranged to be attached to the wall of the tunnel 5 such that the image held in the frame 6 can be viewed readily by passengers in the train 1. In this example the frame 6 is attached to the wall by a hinged support arrangement 8, which allows access to cables 9 positioned behind the frame 6 and also enables removal of the image from the frame so that the image can be replaced.

[0013] Figure 3 shows a perspective view of an array of frames 6 attached to hinged support 8. It can be seen that the frames 6 are equally spaced. As an example, if the frames 6 have a spacing of 70cm, and the train speed were 35 miles per hour, from figure 4 it can be seen that a moving image with a frame rate of 22 frames per second would be generated. It will be appreciated that the spacing can therefore be set to give an optimum frame rate for the average speed of trains through the particular section of tunnel that contain the system of the invention.

[0014] Figure 5 shows the frame 6 and trigger device 7 in more detail. As can be seen from figure 5, the trigger device is supported below the frame 6, and the relative distance between the trigger device 7 and the bottom of the frame can be varied dependent upon the relative distance between the bottom of the windows 3 of the train and the markers 4. The frame 6, as discussed previously, enables the insertion of images into it in a removable fashion, so that the images can be replaced when desired.

[0015] Figure 6 is a schematic diagram to assist in the explanation of the operation of a preferred example of trigger device 7. In this example the trigger device 7 has a light transmitter 10, which in this example is a source of infrared light. Light from the transmitter 10 passes through a polariser 11 and illuminates the marker (which in this case is a reflector) 4 positioned beneath the window 3 on the train 1. In this example the marker 4 is a series of pyramid-shaped reflectors 12, which ensure that light which is reflected therefrom keeps the same polarisation as when it is received. Light reflected back from the reflector 4 passes through a second polarising filter 13, which only allows light of a particular polarisation through to a receiver 14. When the receiver acknowledges the receipt of light it provides a trigger to a flash light (not shown) which illuminates the frame 6. Adjacent trigger devices 7 may have filters 11, 13 of differing alignment, so that they do not accidentally trigger one another.

Claims

1. An image display system comprising:

a row of images, each image having a respective illumination device; and

a trigger device associated with each image, each trigger device arranged such that, in use, it detects a marker associated with each window on a train passing its associated image and activates its associated illumination device.

2. A system according to claim 1, wherein the illumination device is a flash light.

3. A system according to either claim 1 or claim 2, wherein the illumination device includes a Xenon type bulb.

4. A system according to any one of claims 1 to 3, wherein the images are held in a row of frames, each of which is arranged to be attached to a wall in use.

5. A system according to claim 4, wherein each frame is hinged to allow replacement of the image that it holds.

6. A system according to any preceding claim, wherein the trigger device associated with each individual frame

is arranged to be activated by an optical reflector positioned below each window on a train.

7. A system according to claim 6, wherein the trigger device contains and optical transmitter and an optical receiver triggering the illumination device when transmitted light from the transmitter is received by the receiver from the reflector.

8. A system according to claim 7, wherein the transmitted light is from the near infrared part of the electromagnetic spectrum.

9. A system according to claim 8, wherein the reflector is arranged such that it does not alter the polarisation of light that it receives, the transmitter transmits polarised light, and the receiver only accepts light of one polarisation such that the receiver is only triggered by light of appropriate polarisation.

Drawing