FIELD This invention relates to visual displays particularly of the"air shower"type resembling those of confetti or rice, or of the"indoor fireworks"type (where non-incendiary showers of particles are involved), and in particular the invention relates to materials and methods for providing displays of the above types, preferably in darkened areas.

BACKGROUND There is often a desire to celebrate an event with a public display of some spectacular and attention-holding type. Traditionally fireworks have provided suitable displays. Fireworks are widely used on 5th November, 4th July, or the Chinese New Year (for example).

Fireworks can be of the"self-drive"variety or may be mounted as public displays and elaborate displays can be used that employ electrical and/or fused sequencing as well as a broad knowledge of pyrotechnics and chemistry on the part of the designers. Sometimes these displays are enhanced by the use of directed visible laser light. Fireworks are not suitable for indoors use, because of the danger of fire, or of poisoning from toxic smokes.

Furthermore there exists another group of traditional visually based celebrations involving showering particles, such as of confetti or rice, over people or over an area. These particles may serve their function while travelling (falling) through the air, or perhaps after landing upon some object or person, or both. The immediate problem to be solved might be regarded as providing a spectacular dynamic display indoors, with safety, yet retaining at

least some of the inherent interest level of a fireworks display. This invention is likely to use strontium aluminate-see US 3294699 to Lange, US 5885483 to Hao et al, JP 000268463 (1994) or UK 1190520.

OBJECT It is an object of this invention to provide for an attention-claiming display having no pyrotechnical component, or at least to provide the public with a useful choice.

STATEMENT OF INVENTION In a first broad aspect the invention provides a non-incendiary display for providing a visually appealing shower of particles capable of emitting light without undergoing a light-emissive combustion process wherein the display includes a charge comprising a plurality of dispersible particles, each particle being capable, on dispersal, of floating in the air for a period of time, each particle including at least one optically active material capable of emitting light in a manner having appeal to the eye as a result of being illuminated by light, and display delivery means capable of accepting the charge and of dispersing the plurality of particles from the charge into the air, so that the shower of particles may be visible against a background at least while being suspended in the air.

In a related aspect the invention provides a particle for a non-incendiary display as previously described in this section, wherein an at least one optically active material is a luminous substance comprising zinc sulphide together with glow-enhancing additives.

In a second related aspect the invention provides a particle for a non-incendiary display as previously described in this section, wherein an at least one optically active material is a luminous substance selected from the range of alkaline earth metal aluminates together with glow-enhancing additives.

In a third related aspect the invention provides a particle for a non-incendiary display as previously described in this section, wherein an at least one optically active material comprises strontium aluminate together with glow-enhancing additives.

In a fourth related aspect the invention provides a particle for a non-incendiary display as previously described in this section, wherein an at least one optically active material is selected from a range of fluorescent substances including those capable of emitting light when illumi- nated by ultraviolet light.

In a fifth related aspect the invention provides a particle for a non-incendiary display as previ- ously described in this section, wherein an at least one optically active material is selected from a range of reflective substances capable when illuminated of giving rise to at least one specular reflection.

In a sixth related aspect the invention provides a particle for a non-incendiary display as previously described in this section, wherein an at least one optically active material is selected from a range of reflective substances capable when illuminated of giving rise to at least one specular reflection; modified in colour by a repetitively deformed surface capable of causing diffraction of visible light.

In a seventh related aspect the invention provides a particle for a non-incendiary display as previously described in this section, wherein an at least one optically active material is selected from a range of dyestuff substances capable in use of imparting a colour to a particle so treated.

In an eighth related aspect the invention provides a particle for a non-incendiary display as previously described in this section, wherein the at least one optically active material is applied onto the surface of a thin, light substrate having a circumscribed configuration adapted for floating in the air after dispersal.

In a ninth related aspect the invention provides a particle for a non-incendiary display as previously described in this section, wherein the substrate is a thin plastics material capable of retaining an impressed configuration.

In a tenth related aspect the invention provides a particle for a non-incendiary display as previously described in this section wherein the substrate is treated with a material capable of inhibiting combustion.

Alternative preferred materials capable of emitting light include the range of fluorescent materials including those capable of emitting light when illuminated by ultraviolet (black) light.

Generally the particle also includes an inert substrate.

Preferably the substrate is selected from the range of paper, plastics, or foodstuffs.

One preferred plastics material is a film of high density polyethylene and a preferred film thickness is about 2 mils.

Preferably the substrate is degradable and more preferably the substrate is bio-degradable.

Optionally the substrate may be a plant material such as a seed. An example seed is rice.

Another example seed is a sycamore seed from the sycamore tree.

Preferably the at least one material capable of emitting light is applied on to the surface of the substrate, though optionally the material is mixed within the substrate.

An example method of application comprises dusting the material onto a surface previously coated with an at least temporarily sticky layer of another material. An example sticky layer is comprised of latex.

In a second broad aspect the invention provides apparatus for manufacture of a plurality of dispersible and visible particles for use in an attention-claiming display as previously described in this section, wherein the apparatus includes embossed rollers capable of embossing a sheet of substrate and means to cut individual items from the stock.

Thus the invention provides a modified form of confetti (by which we mean a plurality of similar disks of paper or like material, each having a diameter of about from 4 to about 10 mm) complying with the description given previously in this section.

Preferably the confetti is further modified so as to remain airborne for an extended period.

An example modification comprises pressing a profile having raised and lowered components into each individual piece of confetti, and an example profile is as illustrated in Fig 1.

Another example modification comprises forming the circumference of a disk into a feathered or tufted edge.

Optionally the particle shapes are not limited to the traditional round confetti shapes or the like, but include strips and streamers or the like; whether in a coiled or otherwise compressed configuration for storage and distribution, or in an open configuration for use.

In a third broad aspect the invention provides a charge of particles for a non-incendiary display as previously described in this section, wherein the charge is comprised of a plurality of particles as previously described in this section within a package; the package having a wall at least part of which is capable of being burst; the package having a wall at least part of which is capable of admitting an effective amount of light into the package prior to use.

In a related aspect the invention provides a charge of particles for a non-incendiary display as previously described in this section, wherein the charge comprises an at least partially frangible container including means capable, on demand, of the generation of a compressed gas within a compartment; the compressed gas so generated being capable of causing the container to break open and release the plurality of particles into the surrounding area.

In a fourth broad aspect the invention provides delivery means for a non-incendiary display as previously described in this section, wherein the delivery means includes (a) at least one source

of particle-exciting light capable of causing the particles to radiate light, and (b) a cannon adapted to receive a charge as previously described in this section, within which cannon a compressed gas is capable of being rapidly released in order to impel the plurality of particles from the charge into the air.

Preferably the propelling means or cannon is reusable.

Optionally the propelling means or part thereof may be disposable and may be capable of trans- mitting a particle-exciting light into its interior prior to use.

In a related aspect the invention provides delivery means as previously described in this section, wherein the cannon is provided with means capable of generating an aerodynamic vortex within the tube in order to surround and/or precede the charge of particles.

In a second related aspect the invention provides delivery means as previously described in this section, wherein the at least one source of particle-exciting light capable of causing the particles to radiate light is positioned within the delivery means in order to irradiate the charge with an effective amount of light prior to emission.

In a third related aspect the invention provides delivery means as previously described in this section, wherein the at least one source of particle-exciting light capable of causing the particles to radiate light is positioned within the delivery means in order to irradiate the charge with an effective amount of light after emission, while airborne.

Preferably the exciting light is of wavelengths shorter than that of blue light.

More preferably the exciting light emanates from a source of light that comprises part of the propelling means.

In a fifth broad aspect the invention provides means for propelling a charge comprised of a plurality of particles as previously described in this section into the air; the means comprising a form of tube or cannon in which a compressed gas; suddenly made available, is used as a motive force to impel the charge from the cannon.

Preferably the charge is provided as a unit; comprising a load of particles as previously described in this section, held within a sealed container having a frangible aperture.

Preferably the aperture is surrounded by an aperture retaining means.

Preferably the sealed container is at least partially filled with a substantially dry gas.

Preferably the sealed container comprises a flexible bag, such as a plastic bag, capable of admitting an exciting light.

Preferably the means for propelling the charge provides a tube or cannon having a base adapted to receive the frangible aperture of the sealed container; the body of the sealed container being held within a bursting means capable of rapidly forcing the sealed container against the frangible aperture so that the aperture bursts and allows release of the load of particles into and 150 from the tube or cannon.

One preferred bursting means comprises the rapid release of a charge of compressed gas into an enclosed space surrounding the sealed container so that the internal pressure within the sealed container rises and causes the frangible aperture to burst.

Another preferred bursting means comprises the release of a movable object capable of 155 confining the sealed container into a rapidly diminished space so that the internal pressure within the sealed container rises and causes the frangible aperture to burst. A preferred movable object comprises a piston-like device impelled by a compressed spring means upon release of a triggering means.

Optionally at least some gas may be fed into the tube beyond the frangible diaphragm in order 160 to surround and/or precede the charge of particles In a sixth broad aspect the the invention provides means for propelling a charge comprised of a plurality of particles as previously described in this section into the air; the means comprising a form of frangible container within which an internally generated compressed gas is used to cause the container to break open and release the plurality of particles.

165 Preferably the frangible container is constructed of a laminar material and has more than one compartment.

Preferably a first base layer of the frangible container possesses a relatively high strength and forms a wall of a pressure-generating compartment.

Preferably a second wall of the pressure-generating compartment of the frangible container 170 possesses an intermediate strength and forms a wall of a compartment within which particles according to the invention are stored.

Preferably a third wall of the the frangible container forms a second wall of the compartment within which particles according to the invention are stored and the third wall possesses a lowest strength, so that during use, after compressed gas has burst through the second layer 175 into the particle-storage space, the third wall will burst thereby releasing the particles into the surrounding area.

Preferably the compressed gas is generated from a chemical reaction.

Preferably the chemical reaction involves the release of a relatively non-toxic gas from a chemical reaction in which relatively non-toxic substances are used.

Preferably the chemical reaction may be set off by breaking open a frangible vessel holding a reactant. (A preferred frangible vessel is a sealed plastic bag).

Preferably the non-toxic substances used include an alkali metal carbonate/bicarbonate, and an acid for example as sodium bicarbonate in a solid form, and vinegar.

Optionally a"baking powder"type of composition may be used, including a dry mixture of sodium bicarbonate and a solid organic acid, and water, contained in a frangible vessel as a reaction-promoting agent.

Preferably the releasing means (the frangible container) is capable of being activated when placed upon a surface.

Optionally the releasing means (the frangible container) is activated while within the air.

Optionally the releasing mechanism may comprise a lighter-than-air device such as a helium- filled balloon.

In a seventh broad aspect the invention provides means for further enhancing the visual appearance of the material while in view, the enhancing means comprising the provision of directed lighting selected from the range of ultra-violet light, visible light, or infra-red light.

In a related aspect the invention provides means for further enhancing the visual appearance of the material while in view, the enhancing means comprising the provision of directed lighting in the form of at least one directed beam, such as a laser beam.

Optionally the laser beam is moved about so as to delineate recognisable shapes.

Optionally a form of laser beam having the effect of quenching a previously luminous surface may be used.

Optionally the directed lighting may comprise flood lighting.

Optionally the directed lighting may be pulsed or flashed and an example is strobe lighting.

Optionally the lighting may be coloured and designed to interact with appropriately dyed particles.

PREFERRED EMBODIMENT

The description (s) of the invention to be provided herein is/are given purely by way of illustrative example and are not to be taken in any way as limiting the scope or extent of the invention.

DRAWINGS Fig 1: shows an aerodynamically shaped article of confetti and a pair of rollers for replicating such articles from a sheet of a stock material (Example 2).

Fig 2: shows a two-compartment device capable of being burst by internally generated gas and then flinging a charge of luminous particles into the air. (Example 5) Fig 3: shows a one-compartment container capable of being burst by externally applied pressure against a cannon tube base, so that a charge of luminous particles can be flung into the air. (Example 6) Fig 4: shows another cannon device adapted to provide excitation to a charge of luminous particles before propelling them into the air. (Example 4) The invention in summary relates to material which may be considered as"luminous confetti" or"glowing confetti" (example 1) according to this specification, to means for spraying the material into the air (examples 4,5, and 6), to means for retaining the material in the air for an extended period (examples 2 and 3), and to means for enhancing the effectiveness of the resulting display (example 7).

EXAMPLE 1 This invention relates to"indoor fireworks"or the like, where the use of conventional chemical explosives or the like particularly as propellants is undesirable. With the components of the invention, it is possible to produce displays having many of the characteristics of fireworks, especially when done in a darkened room or at night. Essentially, much of the appeal of fireworks comes from the shapes and general appearance of coloured, intensely bright, moving points of light. Sounds (explosions), smoke, and smells add to the sense of occasion. This invention makes use of recent developments in the class of luminescent/phosphorescent/ fluorescent materials, all of which can generally be described as being capable of emitting light as a result of excitation by light. There is no chemical smoke, but absence of the pollutants (such as the quite toxic barium compounds) that fireworks smoke is comprised of is an advantage. In general in this invention light-emitting particles are thrown into the air and are to be appreciated as they float to the ground. Sometimes the optical properties of the particles after landing may make them desirable for collection, such as by children, and then disposal

issues are mitigated. On the other hand, substantially no toxicity is then most desirable in case fallen particles are handled, brought into contact with mucous membranes, or even ingested.

Hence we prefer to cloak any potentially toxic components in a protective coating. A solidified resin is one example of a suitable coating. Note that the strontium aluminate appears to be quite non-toxic.

The preferred type of"confetti"particle for use in an attention-claiming display according to the invention comprises an inert substrate sheet material (such as a plastics material such as "Mylar" (PET: polyethythene terephthalate), PVC: polyvinyl chloride, or the like)-and of the plastics, we currently prefer HDPE: high-density polyethylene. A thickness of two mils has been found suitable. Paper (at least some types) is also eminently suitable and is far more degradable than most kinds of plastics material. There are many other suitable bio-degradable materials, such as potato starch products (such as pellets or flakes), rice, or the like, and various plant or seed components such as husks, air-borne seed carriers (dandelion heads, sycamore seeds, or the like).

The shapes of particles is variable. Small discrete particles form one group; elongated particles are a second, streamers are a third, and elaborately shaped particles having useful aerodynamic properties are a fourth group. Clearly a mixture of shapes is likely to be visually more inter- esting than a single shape. We will discuss shape in more detail later in this section.

Optical activity 1: substances capable of emitting visible light: In order to make the particles visible, particularly in the dark, we make use of at least one material capable of emitting light mixed with, or more preferably coated over, each particle so that the particle when suitably activated is particularly visible against a background.

Luminous substances Preferred luminous materials provide a substantial fraction of the enhanced appearance of the invention. There is a range of substances capable of emitting light as a result of being illumi- nated by a suitable type of light and we prefer those materials that continue to emit light for a substantial period after illumination. A preferred material includes the range of alkaline earth metal aluminates, such as strontium aluminate. See US 5885483 to Hao et al.

Another luminous material (known for some time) is zinc sulphide but strontium aluminate in similar amounts has a much greater visual effect. On the other hand, ZnS can be excited with a short exposure to light whereas the strontium compound requires several minutes-though this can be varied with appropriate activators. In the end a combination of both zinc sulphide and strontium aluminate may best satisfy requirements.

Fluorescent substances.

In general these substances, when illuminated, immediately emit light of a longer wavelength that the wavelength of the illuminating light. Delayed release of light is not usually a consid- eration but in the case of this invention, delayed release may be used. Alternatively, if delayed release is substantially absent an ultraviolet strobe light (for example) will cause the fluorescing material to flash visibly. Conveniently ultraviolet (black) light may be used to illuminate fluorescent materials because it is not itself visible.

Some substances that are fluorescent under ultraviolet light are not clearly visible in white light, (the class of Ultraviolet Invisible Inks) while others are fluorescent even under white light.

Either type of substance may also be used within this invention.

Application of substance to particle: We have carried out trials wherein the material capable of emitting light is mixed within the substrate. Incorporation of"glow pigments"such as strontium aluminate within the paper during manufacture at from 5 to 40% by weight has been trialled but there seemed to be some destruction of the luminosity. Improved results were obtained by mixing our glow pigments together with the fire retardant substances commonly added after paper manufacture. Accord- ingly, one method of producing luminous confetti comprises the use of a machine capable of maintaining a suspension of glow pigments within a fire retardant solution and capable of applying that suspension to paper which is later cut into particles (such as confetti shapes).

Further trials involve the application of one material capable of emitting light onto the surface of the substrate. For example, we have tried dusting the material onto a surface previously coated with an at least temporarily sticky layer of another material. An example sticky layer is comprised of latex although many other suitable materials, similarly capable of providing a sticky layer exist.

Given the possibility of deterioration of the"glow capability"after storage under non-anhydrous conditions for possibly some years we believe that it is advantageous to encapsulate the"glow pigments"in a coating of an insoluble material such as a resin. Furthermore this treatment would reduce the toxicity of the pigments (see previously).

We have carried out successful trials with from 5 to 50% by weight of glow pigments on substrates such as confetti and thin plastics sheets (as described elsewhere in this section).

From 30 to 40% appears to provide an optimum result.

Optical activity 2: substances capable of reflecting visible light:

At least some particles in a mixture of items to be launched may be made of something shiny.

They are capable of reflecting incident light such as with a specular or mirror-like reflection so that (particularly when lit by means of a strong beam of light) flashes of intense light are seen from time to time by an observer. Then, a suitably lit shower of particles according to the invention acquires an extra property. Example reflective surfaces include metallised plastic films and these may have surfaces modified so as to form a fine diffraction grating and hence cause spectral colours to be seen on reflection.

EXAMPLE 2 The physical shape of the"particles"which so far have been considered as"fragmented flat material"may take a number of shapes. In principle, the particles are disks, comprising a modified form of confetti, and in one form it is further modified so as to remain airborne for an extended period.

An example modification comprises providing a profile having raised and lowered components into each individual piece of confetti. An example is illustrated in Fig 1, where (above) a disk 100 has had a central dome 102 and an external rim 101/103 pressed into it. Perhaps this item may be from 0.5 to 1 cm across. This shape comprises one example of an"aerodynamic"shape capable of remaining in the air for longer than a plain disk of confetti. Paper darts or the like may also be suitable.

Other modifications of shape having a useful effect may include shapes based on or actually using biological materials such as feathers, air-borne seeds (thistle or sycamore), or fine threads (spider web). Confetti shapes may be provided with a rim of fibres or tufts in order to increase air resistance. If the particles are not considered as being limited to the traditional round confetti shapes or the like, but include strips and streamers or the like, the parallel between a spider web and at least one type of particle becomes more evident. It may be possible to provide elongated particles in a coiled-up of otherwise compressed form prior to use.

Another way to maintain particles in the air comprises use of air jets, light gases, or even hot air. Static electricity might be usable.

EXAMPLE 3 An example method (also included in Fig 1) for making such a disk might comprise a pair of rollers 105,106 which have mating surfaces configured to press and cut shapes of this type from a flat sheet of stock material 104 ; preferably a sheet which has already received a coating of glow pigments 110. (Only a small portion of the concentric configured roller surface 107 is

shown here). Pieces 108 pressed and cut from the flat sheet are shown falling into a collecting box 109. Optionally the embossing means and cutting means are provided upon one or more planar dies capable of being pressed against each other with the stock in between. If the stock material is paper or a deformable (possibly thermoplastic) plastics material, the pressed shape should be retained for the life of the particle.

EXAMPLE 4 In this and in following examples we discuss various means for propelling a charge of optically interesting particles into the air.

One example means comprises a tube or cannon in which a sudden burst of compressed gas (such as carbon dioxide from a cylinder) is used as a motive force to impel the charge (held as a firm lump inside the tube) from the cannon. The associated noise, which may be loud, may well have an attention-gathering effect analogous to the noise from a pyrotechnical fireworks display.

Another means 400 includes a container 401 (see the sectional view in Fig 4), inside which there may be stirring means such as a motor 405 and fan to agitate the particles to be released (or perhaps some particles but not all; streamers would be better held separately), illumination means (such as ultraviolet light from fluorescent tubes 207,207)-or quartz-halogen filament lamps-to pre-illuminate the particles so that on release they are already emitting light, (3) means to raise the internal pressure (here a cylinder of gas 403 with a tap 402 coupled to the interior of the box 401, and a rapid release device 404 which may be a weakened diaphragm across an outlet aperture which will burst once the pressure across it is sufficiently high and allow the interior of the container to be emptied through the director tube 203. Alternatively the release device 404 may be a reusable diaphragm capable of flipping from a closed to an open state if the pressure across the diaphragm exceeds a set value, and then reverting to a closed state if the pressure differential then falls again.

EXAMPLE 5 See Fig 3; sectional view at left, top view at right. As another option; this one avoiding provision of a cannon, we propose the development of (1) a self-contained disposable container 300 and release mechanism comprising (la) a preferably at least partially clear-walled and preferably rather flat sealed bag separated internally into at least two compartments by a shared frangible dividing wall 307 orientated along the plane of either flat surface, (lb) a first compartment 301 containing a charge of luminous particles 108 according to the invention and having a defined weakened (most frangible) outer wall (see 306 in the right-hand drawing),

capable in use of bursting and releasing the charge, (lc) the first compartment sharing a less frangible second wall with a second compartment-that wall capable of bursting on devel- opment of sufficient pressure within the second compartment 304; (ld) the second compartment being equipped with a chemical gas-generation means such as a supply of sodium bicarbonate (baking soda) as dry powder 303 together with a breakable capsule 305 (for example) holding an equal amount in chemical terms of acetic acid (vinegar) in relation to the sodium bicarbonate, so that when the capsule is broken, the vinegar reacts with the dry baking soda a rapid buildup of pressure from the carbon dioxide generated by the chemical reaction occurs, and finally, (le) the other wall 304 of the second compartment is not intended to burst.

In use, the charge 108 within this device is subjected to irradiation from an exciter lamp, and after breaking the capsule in some convenient manner the device is either set on the ground or thrown into the air and the charge of particles according to the invention is flung from the container along with a loud noise as soon as enough gas pressure has built up. The outer, most frangible wall bursts very soon after the shared wall bursts. An advantage of this self-contained device is that no other releasing device is required and that the manufacturer has control over the degree of frangibility of the diaphragm. Packs of this type may be made in a"frisbee"-like rounded shape so that they can be flung sideways after being triggered. The packs may be relatively square-or triangular or hexagonal for example.

A surface view of one such pack is shown at the right; 301 indicates the cover over the luminous particles, 302 is part of the non-bursting wall, and 306 indicates deliberately weakened lines across the surface layer which are intended to give way under pressure. Possibly the entire device could be made as a single compartment; the use of two compartments was intended to retain separation of the gas-generating material and the particles to be displayed for as long as possible.

EXAMPLE 6 As another option (see Fig 2; charge at the left and cannon at the right) which requires a kind of cannon device 203, we propose the development of a disposable container 200 comprising a preferably clear-walled, sealed plastic bag (or perhaps a waxed paper bag or some other preferably translucent, impermeable material-with regard to water); the bag having having a defined weakened (frangible) area 201 surrounded by a firm retaining border such as a wire ring (so that the entire bag is not discharged through the cannon). In use, the bag is to be placed adjacent to an emission aperture inside the cannon. The bag is supplied partially filled with a dry, substantially inert gas (which will in use burst through the preformed weakened (frangible) diaphragm) and a charge of particles 108 according to the invention will be emitted. The

compatible cannon 203 (shown here in sectional view in a pre-release state) including stirring means (optional; not shown) to shake up the contents of the bag, an (optional) excitation light 207 (wiring not shown) capable of shining through a window and into the bag, reaching the luminous decoration on the particles within, and a mechanical applicator of force (for example, a relatively strong compression spring 204 pushing from underneath piston 205; capable of being released by trigger 209, or possibly means to release a burst of a compressed gas into the space below the bag. Either release means is preferably capable of quickly compressing the plastic bag which lies with its frangible area 201 against an aperture within the cannon so that on application of sufficient pressure the bag bursts into the base of the cannon and the charge of now luminous particles within is blown outward. Optionally, supplementary gas is introduced within the barrel 203 of the cannon (for example through bypass tube 206 and nozzle 208) to add to the"blowing out"flow of gas and optionally this may be supplied through an eccentri- cally placed nozzle (as shown: 208 in order to blow the charge out within a vortex, with the objective of making the particles reach a higher altitude before falling back. The bypass tube may also comprise a handle. Optionally the bag of particles may be subjected to at least some of a dose of excitation light externally, before insertion of the bag into the cannon through a loading aperture (not shown). (Excitation may be a time-consuming procedure). This version has several advantages. The disposable container keeps all the"messy parts"together, along with the diaphragm, until use (even in a strong wind) and that the manufacturer has control over the degree of frangibility of the diaphragm. A compressed gas supply is not required if a strong spring can be tensioned, then released as shown. Sales of self-contained disposable containers 200 (in a number of varieties perhaps) is convenient. Storage of the luminous particles in dry conditions is facilitated, and there is no chemical mess problem during storage or during use, nor any risk of premature ejection. The reusable cannon 203 may be sold or hired.

EXAMPLE 7 This example relates to modulation of the appearance of clouds of glowing confetti-or even sheet luminous material-by means of laser light. There are at least three forms that this can take: (1) shining visible laser light off individual particles preferably reflective particles, so that they appear to flash; (2) shining visible laser light onto a cloud of particles using directed mirrors that cause the laser beam to appear to form symbols or shapes within the cloud, (3) shining visible laser light onto glowing surfaces including luminous materials and thereby causing a quenching of the excitation. Alternatively, for the first two options at least, the laser light may be ultraviolet so that only its fluorescent effects are made visible.

EXAMPLE 8 A further means for carrying a charge of optically interesting particles into the air and releasing the particles at a certain date is provided here. This means is a balloon; preferably a lighter- than-air balloon such as a helium-filled balloon capable of rising to a suitable height and then of releasing a load of particles. The balloon may be captive or free. The particles might be carried within the envelope of the balloon and the whole balloon may be caused to burst by some means. Alternatively the particles might be carried in a separate carrier supported from the balloon. Inflammable fills such as those including hydrogen or coal gas are more likely to result in setting fire to the contents, although in practice the use of flame-retardant confetti might counteract that effect yet allow a good attention-getting bang well apart fr. om the viewers.

(Of course use of an inflammable fill is inconsistent with the title of the specification). A suffi- ciently loud bang may follow any bursting of the envelope.

Indeed, an aircraft may be used to carry material to a height.

Preferred release means include (1) a weak envelope that bursts at a certain altitude by distension of its fill, (2) a container that bursts as a result of contact with a part of a slow- burning fuse, or (3) a container or an envelope that is burst by external actuation; perhaps a wire applied against the balloon is heated and causes the envelope to rupture-and the external actuation may be in response to a signal from a timer, an altimeter, or a remotely controlled device perhaps controlled from the ground by someone who is orchestrating the display.

COMMERCIAL BENEFITS or ADVANTAGES It will be appreciated that a"luminous confetti"of the type described herein, bearing suitably excited phosphors, especially when delivered by means of a releasing mechanism capable of boosting the visual impact of the confetti (or streamers or other particles), can provide a satis- factory and safer alternative to fireworks and the effects are provided without the use of flame or explosion. The effects will be novel. Furthermore, the concept is amenable to commercial exploitation through the use of prepared packs, modules, bags, or devices as well as through the use of specialised releasing devices. Although the effects may currently require reasonably darkened viewing spaces, technical developments will result in noticeably brighter displays.

Although several preferred examples as described above have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions, and substitutions are possible without departing from the scope and spirit of the invention as set forth in the following claims.