WO2007138275A2

WO2007138275A2 - Display device

Info

Publication number: WO2007138275A2
Application number: PCT/GB2007/001932
Authority: WO
Inventors: James Butcher
Original assignee: James Butcher
Priority date: 2006-05-31
Filing date: 2007-05-24
Publication date: 2007-12-06
Also published as: GB0610682D0; WO2007138275A3

Abstract

A display device which is at least one metre in diameter includes superimposed light-transmitting walls (10 -13) defining intervening chambers (18 - 20) containing two immiscible fluids having different densities. One of the fluids is a coloured liquid and the other fluid (21) is a substantially colourless gas. The walls are mounted for rotation, and each chamber includes projections (30) forming cup-shaped recesses (31) at the periphery of each chamber which collect gas at the top of the chamber and release it into the liquid. The superimposed walls (10 -13) are separated by spacer rings (14 -16) containing evacuation ports (51 - 53) through which a proportion of the gas has been removed. The pressure of the gas is thus reduced below atmospheric pressure such that the external pressure acting on the walls at least partially counteracts the weight of coloured fluid acting outwardly on the walls. The evacuation ports (51 - 53) may be permanently re-sealed or provided with non-return valves.

Description

DISPLAY DEVICE

TECHNICAL FIELD OF THE INVENTION

This invention relates to a display device of the kind which includes a plurality of superimposed light-transmitting walls defining at least one intervening chamber containing two immiscible fluids having different densities and which are distinguished by the fact that the fluid with the greater density is coloured and the less dense fluid is substantially colourless, in which the said walls are mounted for rotation about an axis which is substantially normal to their plane, and the or each chamber includes means which are circumferentially arranged at the periphery of the or each chamber for collecting fluid at one region of the chamber, carrying it to another region of the chamber and releasing the fluid as the walls rotate.

BACKGROUND

EP 1 233 393 A of Trevor Butcher discloses a display device of the kind described above in which the or each chamber is substantially filled with the coloured fluid leaving a gap adjacent to the top of the chamber containing the less dense fluid, and the means for collecting the fluid includes a plurality of cup-like recesses each having substantially circumferentially extending inner and outer walls with a mouth at one end thereof which collects the less dense fluid at the top of the chamber and carries it to the bottom region of the chamber where the less dense fluid is released to form discrete flattened colourless volumes which rise through the coloured fluid. In a preferred form of the device the coloured fluid is a liquid and the less dense fluid is a gas.

Whilst such a display device is very effective when the diameter is relatively small it has been found that if the diameter is increased, e.g. to about 1 metre, the weight of fluid between the walls increases greatly. Consequently, in order to prevent distortion of the walls their thickness must be substantially increased, resulting in an even greater increase in the size and weight of the device.

The present invention seeks to provide a new and inventive form of display device in which the diameter can be increased without a disproportionate increase in weight.

SUMMARY OF THE INVENTION

The present invention proposes a display device which is characterised in that the less dense fluid is a gas and the pressure of the less dense fluid is reduced below atmospheric pressure such that the external atmospheric pressure acting on the walls at least partially counteracts the weight of coloured fluid acting outwardly on the said walls.

BRIEF DESCRIPTION OF THE DRAWINGS The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice. In the drawings:

Figure 1 is a general view of a display panel for use in a changeable colour display in accordance with the invention;

Figure 2 is a front view of a display device which incorporates the display panel;

Figure 3 is a front view of one of the four transparent walls incorporated in the display panel;

Figure 4 is front view of one of the spacer rings of the display panel; and

Figure 5 is a radial section through an edge region of the display panel.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to Fig.1 , the display device includes a circular display panel 1 which may have a diameter in excess of one metre. The panel 1 is mounted on a central sub axle 2 which is driven by an electric motor (not shown) causing the panel to rotate in the direction of arrow A. The panel could alternatively be rotated by a belt drive or supported on driven friction rollers if desired. The panel 1 may be mounted in a housing 26 as shown in Fig.2, which is supported on a base 27. The panel 1 includes four transparent non-coloured plastic disc-shaped walls 10-13 (Fig. 3) separated by spacer rings 14 -16 (Fig. 4) with a uniform gap of about 1.5 mm (preferably 1 to 2 mm) forming three substantially circular sealed chambers 18-20. The chambers are filled with different coloured translucent liquids, e.g. cyan, yellow and magenta, leaving an air gap 21 adjacent to the top of each chamber. Low viscosity liquids may be used, e,g, water coloured with ink. Other gases could be used instead of air. The spacer rings 14-16 are formed with a series of internal L-shaped projections 30 which are also sealed to the transparent walls 10-13 to form cup-shaped circumferentially extending recesses 31 with mouths 32 which open in the direction of rotation. Opposed depressions 34 can be formed in the circular walls 10-13, shown in Fig. 3, to increase the capacity of the recesses 31.

Although the diameter of the panel 1 is relatively large, and the weight of water relatively high, the walls 10-13 are relatively thin. This is because during manufacture of the panel air is removed from the air gaps 21 via evacuation ports 51-53 in the spacer rings 14-16, shown in Fig. 5. After removal of air the ports are sealed using a self-setting resin or similar material to maintain the partial evacuation of the chambers 18-20. The external atmospheric pressure acting on the outer walls 10 and 13 counteracts the weight of coloured fluid acting outwardly on the said walls. Since the adjacent sealed chambers are at substantially the same pressure the intermediate walls 11 and 12 are not subject to distortion since the pressure is balanced on both sides.

Instead of providing sealed ports 51-53 the chambers 18-20 could be partially evacuated via non-return valves. The panel 1 is illuminated from behind, either by natural daylight or by means of at least one fluorescent tube of the kind which emits white light. As the panel rotates the recesses 31 collect air at the top of the chamber and carry it to the bottom region of the chamber where the air is released. The air then forms discrete flattened colourless bubbles which rise through the coloured liquid and filter the light passing through the panel to present continuously changing shapes and colours to an observer looking through the panel as the bubbles overlap in different combinations.

It will be appreciated that the features disclosed herein may be present in any embodiment of the invention in any feasible combination. Whilst the above description places emphasis on those areas which, in combination, are believed to be new, protection is sought for any inventive combination of the features disclosed herein.

1. A display device of the kind which includes a plurality of superimposed light-transmitting walls (10-13) defining at least one intervening chamber (18-20) containing two immiscible fluids having different densities and which are distinguished by the fact that the fluid with the greater density is coloured and the less dense fluid is substantially colourless, in which the said walls (10-13) are mounted for rotation about an axis (2) which is substantially normal to their plane, and the or each chamber (18-20) includes means (30, 31 , 32) which are circumferentially arranged at the periphery of the or each chamber for collecting fluid at one region of the chamber, carrying it to another region of the chamber and releasing the fluid as the walls rotate, characterised in that the less dense fluid (21 ) is a gas and the pressure of the less dense fluid is reduced below atmospheric pressure such that the external atmospheric pressure acting on the walls at least partially counteracts the weight of coloured fluid acting outwardly on the said walls.

2. A display device according to Claim 1 in which the superimposed light-transmitting walls (10-13) are separated by spacer rings (14-16) containing evacuation ports (51-53) through which a proportion of the gaseous less dense fluid has been removed.

3. A display device according to Claim 2 in which the evacuation ports (51-53) are permanently re-sealed.

Claims

4. A display device according to Claim 3 in which the evacuation ports (51-53) are closed by a set sealing material.

5. A display device according to Claim 2 in which the evacuation ports (51-53) are provided with non-return valves.

6. A display device according to Claim 1 in which the superimposed light-transmitting walls (10-13) are at least 1 metre in diameter.