EP1938018A1

EP1938018A1 - Apparatus for producing an optical effect

Info

Publication number: EP1938018A1
Application number: EP06805798A
Authority: EP
Inventors: Noel O'neill
Original assignee: Basic Holdings
Current assignee: Basic Holdings
Priority date: 2005-09-21
Filing date: 2006-09-21
Publication date: 2008-07-02
Also published as: WO2007039126A1; GB2430487A; GB0519264D0; GB2430487B

Abstract

An apparatus for providing an optical effect comprises: a housing; a light source mounted in the housing; one or both of (a) a viewing screen in which an optical effect may be observed and light modifying means arranged behind the viewing screen in the path of light from the light source to the viewing screen, and (b) a viewing bed observable by a user from the front of the housing; at least one at least partially light transmitting member having optically differentiated regions, said member being disposed in the path of light from the light source respectively to said light modifying means and/or said viewing bed; and means for moving said light transmitting member with respect to the light source. The at least one at least partially light transmitting member having optically differentiated regions is preferably a disc having differently coloured regions.

Description

Apparatus for Producing an Optical Effect

The present invention relates to apparatus for producing an optical effect and in particular to space heaters including an optical effect and more especially to such apparatus where the optical effect is intended to resemble one or both of burning fuel or flames. In particular embodiments the invention relates to an optical effect features of which are controllable by a user.

BACKGROUND

The prior art is replete with electric heating appliances (hereinafter electric fires) which include means for simulating burning fuel and/or flames. Typically such electric fires include a heat source which historically has been one or more radiant heating bars but is now more commonly a fan heater comprising heating element and a fan to blow air over the hot heating element. The air exits the housing through a suitable aperture to heat the room. For producing the effect of burning fuel a simulated fuel bed is provided which often comprises a plastic moulding shaped and coloured to represent fuel, embers and ashes. Typically the fuel bed will be primarily coloured orange and red with brown, black and grey areas to represent burning fuel. Discrete pieces of fuel, or simulated fuel, may be placed on the fuel bed, to resemble logs or coals, as required. The fuel bed is illuminated from below by a light source and means are provided in the path of light from the light source to the fuel bed to interrupt or reflect the light to give the impression of movement and changes in intensity. For the simulation of flames, a viewing screen is provided, usually above the fuel bed. Light from the light source is caused to fall on the rear of the viewing screen and flame effect means are interposed between the light source and the viewing screen to alter the qualities of the light and to give the light falling on the viewing screen an impression of movement. Numerous flame effect means have been described in the prior art including static and moving reflectors, apertured webs of substantially opaque material and reflective or partially reflective strips of material, such as silk, suspended in an air flow to cause them to flutter.

EP 1271060 describes a flame effect fire including an opaque screen with flame shaped cut-outs. A dynamic light source is arranged to shine light through the cut-outs and onto a viewing screen. The dynamic light source comprises an apertured plate formed into a cylinder, and a light bulb. The light bulb is arranged within the cylinder and the cylinder is driven by a motor to rotate about its axis. GB 2137336 discloses the flame effect in which two parallel glass plates are used. The plates illuminated from below. Each plate has an applied pattern so that areas are made opaque. The planes are mounted not more than 2 cm apart. The lower plate is circular and is rotated by motor. The upper plate can support a fuel bed in the form of coloured or colourless fuel pieces. Lead crystal is preferred. Light from the light source, after passing through the plates may also be reflected by an upright rear reflecting plate.

GB 2236845 describes a flame effect electric fire in which a laser or other collimated light beam is passed through a first, static, deflector and a second, moving, deflector. The moving deflector executes both rotational and translational motion. The deflectors comprise glass plates with a surface relief pattern effective to refract the light. The light is further modified by a series of lenses.

GB2256040 describes a log effect in which a light source is placed behind a rotating disc having translucent coloured segments. Coloured light from the rotating disc falls on the bunched ends of an array of optic fibres. The remote ends of the optic fibres are distributed through plurality of simulated logs with the intention of giving a glowing effect to the logs.

GB2409323 describes a flame effect fire comprising a light source including a bulb mounted behind a rotatable disc with differently coloured segments. An optic fibre harness is mounted at the other side of the disc so that light which has passed through the disc passes into the optic fibres. The other ends of the optic fibres are distributed around the lower edge and base region of a glass viewing screen, which may be patterned.

WO2005/045321 describes a flame simulating arrangement including a light source and a rotating apertured disc. Light source preferably comprises an array or arrays of LEDs. Light passing through the apertures of the disc is conveyed by the optic fibres to a viewing screen or to a fuel bed of transparent refractory material. The apertured disc is said to act like a rotating shutter to vary the light intensity.

WO2004/079267 describes a gas fire in which a rotating disc is illuminated from below. The disc is patterned or coloured. Light from the disc passes through an angled apertured plate onto the back wall of the fire, behind a fuel bed and gas combustion area. A second light source and disc arrangement can be use to provide background illumination for the fuel bed.

The present invention seeks to provide an enhanced optical effect which may, but does not necessarily, resemble burning fuel and/or flames.

According to a first aspect of the present invention there is provided an apparatus for providing an optical effect comprising:

(i) a housing (ii) a light source mounted in the housing

(iii) a viewing screen in which the optical effect may be observed (iv) light modifying means arranged behind the viewing screen and comprising at least first and second light modifying components (v) at least one at least partially light transmitting member having optically differentiated regions, said member being disposed in the path of light from the light source to said light modifying means; and (vi) means for moving said light transmitting member with respect to the light source.

According to a second aspect of the invention there is provided an apparatus for providing an optical effect comprising: (i) a housing

(ii) a viewing bed observable by a user from the front of the housing (iii) a light source disposed below the viewing bed (iv) at least one at least partially light transmitting member having optically differentiated regions, said member being disposed in the path of light from the light source to said viewing bed; and (v) means for moving said light transmitting member with respect to the light source.

Preferably in this aspect of the invention the apparatus further comprises

(vi) a viewing screen in which an optical effect may be observed, and (vii) light modifying means arranged behind the viewing screen and comprising at least first and second light modifying components, and wherein said at least one at least partially light transmitting member is also disposed in the path of light from the light source to said light modifying means.

According to a third aspect of the invention there is provided an apparatus for providing an optical effect comprising: (i) a housing

(ii) a light source mounted in the housing (iii) a viewing screen in which an optical effect may be observed (iv) a viewing bed observable by a user from the front of the housing

(v) light modifying means arranged behind the viewing screen and comprising at least first and second light modifying components (vi) at least one at least partially light transmitting member having optically differentiated regions, said member being disposed in the paths of light from the light source respectively to said light modifying means and said viewing bed; and

(vii) means for moving said light transmitting member with respect to the light source.

Preferably the light modifying means comprises first and second light modifying components.

In one embodiment the viewing bed viewing bed comprises an at least locally translucent substrate shaped and coloured to resemble burning fuel.

In a preferred embodiment the viewing bed comprises a supporting substrate and discrete viewing elements arranged on the supporting substrate.

In one variation the supporting substrate is a frame or other openwork construction.

In another variation the supporting substrate is a substantially opaque supporting web including a plurality of light transmitting apertures.

In a preferred variation the supporting substrate comprises a web of substantially transparent material and especially a body of glass or transparent plastic. Glass is particularly preferred. In one preferred variation, the discrete viewing elements comprise fuel pieces or simulated fuel pieces.

In a particularly preferred variation the discrete viewing elements comprise pieces of translucent or transparent material and especially pieces of glass. Glass beads are particularly preferred.

Preferably the first light modifying component comprises a reflector mounted behind (with respect to the viewing screen) the second light modifying component.

Preferably the second light modifying component comprises a dynamic light modifying component.

Preferably the dynamic light modifying component comprises at least one at least partially reflective web of material suspended within the housing and means for providing a flow of air to the web of material whereby the web of material is caused to billow or flutter.

In a preferred variation said material comprises a plurality of strips of material.

In an alternative variation the apparatus comprises a web of said material including a plurality of light transmitting apertures.

Preferably in the first and third aspects of the invention the optical effect which may be observed in the viewing screen simulates or resembles flames.

Preferably the means for moving said light transmitting member with respect to the light source includes one or more stepper motors. Geared motors are a somewhat less preferred alternative.

In a most preferred embodiment the or each at least partially light transmitting member having optically differentiated regions comprises a substrate, which substrate is preferably generally planar. Most preferably said substrate comprises differently coloured regions. In another embodiment the or each at least partially light transmitting member having optically differentiated regions comprises a substrate having non-planar surface formations. The formations are thus effective in refracting light transmitted by the substrate.

In another embodiment the at least partially light transmitting member having optically differentiated regions comprises a substrate having opaque or darkened regions.

In another preferred embodiment the or each at least partially light transmitting member having optically differentiated regions comprises a substrate having differently coloured regions and one or more of regions having a non-planar surface, opaque regions and darkened regions.

Preferably in these embodiments the substrate is a substantially planar disc operatively rotated about its axis.

In variations of these embodiments the light transmitting member having optically differentiated regions comprises a first substrate portion and a second substrate portion attached to and angularly arranged with respect to said first substrate portion. Preferably the first substrate portion may comprise a disc and the second substrate portion comprises a substantially cylindrical skirt depending from the disc. Both the disc and the skirt may include optically differentiated regions. The optically differentiated regions are preferably differently coloured regions but may also include one or more of regions having a non-planar surface, opaque regions and darkened regions. Preferably in these variations the first substrate portion is arranged substantially above the light source and the second substrate portion is arranged to substantially surround the light source. In the case where the first substrate portion is a disc and the second substrate portion is a depending skirt, preferably the disc lies above the light source and the skirt is arranged to encompass the light source so that light from the light source passes through both the disc and the skirt.

In particularly preferred embodiments the apparatus of the invention further comprises user-operable control means operable to control the movement of the at least one at least partially light transmitting member having optically differentiated regions. Where the at least partially light transmitting member having optically differentiated regions is a disc, the control means is preferably operable to control the speed of rotation of the disc. Additionally or alternatively the control means is preferably operable to control the rotational position of the disc.

In an especially preferred arrangement the apparatus comprises a plurality of (more especially two or three or four and most preferably two) at least partially light transmitting members having optically differentiated regions and the control means is operable independently to control the movement of said light transmitting members.

Preferably the means for moving said light transmitting member with respect to the light source includes a stepper motor for each respective at least partially light transmitting member and the control means is operable to control each stepper motor independently.

Preferably in the above especially preferred arrangement, the at least partially light transmitting members having optically differentiated regions comprise discs as defined above.

Preferably the control means is operable to control the speed of rotation of the respective discs.

Preferably the control means is operable to control the rotational positions of the respective discs.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example only to the following drawings, in which:

Figure 1 is a general perspective view of a heating apparatus embodying the invention;

Figure 2 is a cross section through the apparatus of Figure 1 ;

Figure 3 is a schematic cross-section along B-B in Figure 2; Figure 4 is a schematic cross-section along A-A in Figure 2; and

Figure 5 is a schematic cross-section through an alternative light transmitting member according to the invention.

DETAILED DESCRIPTION

Referring now to the drawings, the apparatus 10 of the invention comprises a casing or housing 12 typically comprising a rear wall 12A₁ a top wall 12B, a bottom wall 12C₁ a front wall 12D and respective side walls 12E and 12F. The apparatus may also include a canopy 12G. The respective walls are conveniently made from formed metal sheets suitably joined together. The housing 12 will normally include fixing locations and formations for the attachment of internal components and may included external decorative components, such as a simulated fire grate.

The apparatus 10 further comprises a front viewing screen 14 in which an image of flames 16 or other optical effect created by the apparatus 10 may be seen by a user. The screen 14 may be made from glass or translucent plastic. Preferably the screen 14 is formed so that it is partially transmitting of light and partially diffusing of light. For example a surface (preferably the rear surface) of the screen 14 may be provided with fine abrasions. Alternatively, in the case of a plastic screen, the plastic may be doped with a fine pulverulent material such as titanium dioxide powder. In a most preferred construction, the front surface of the screen 14 may be rendered partially reflective, for example by providing the screen surface with a thin silvered layer.

The apparatus 10 is further provided with a viewing bed 18 disposed in front of the viewing screen 14. Where the front surface of the viewing screen 14 is made reflective, and image of the viewing bed 18 can be seen in the viewing screen 14, so enhancing the optical effect. The viewing bed 18 may comprise a plastic moulding shaped and coloured, for example, to resemble burning fuel and embers. More preferably, the viewing bed 18 comprises a supporting substrate 20 and a plurality of viewing elements 22 resting on the supporting substrate 20. For reasons which will become apparent later in the description, the supporting substrate 20 is constructed to transmit light. The supporting substrate 20 may be a sheet or web of material, such as of metal or plastic which, although generally opaque includes a plurality of light transmitting apertures. Alternatively, the supporting substrate 20 may be of openwork construction such as a frame or rack constructed from wires or rods, provided only that the supporting structure 20 can adequately support the chosen viewing elements 22. In the illustrated example, the supporting substrate is shown as substantially planar and horizontal in use. This arrangement is not essential and the supporting substrate 20 may itself be shaped to provide in turn shape to the assembly of viewing elements 22.

In a preferred arrangement the supporting substrate 20 comprises a sheet or web of transparent, or at least translucent, material. Transparent or translucent plastic sheet such as polycarbonate or polypropylene is suitable, but glass is preferred.

The viewing elements 22 comprise discrete pieces of solid material arranged on, and preferably substantially covering, the supporting substrate 20 in order to provide an interesting and attractive optical effect. Where the apparatus 10 is intended to provide a simulation of a real fire, the viewing elements 22 may be real or simulated pieces of fuel, such as coals or logs. In one preferred arrangement, the viewing elements 22 comprise stones such as pebbles, preferably of a relatively pale colour. In another preferred construction, the viewing elements 22 comprise pieces of transparent or translucent material, such as of glass or plastic. In the most preferred construction, the viewing elements 22 are glass beads, which are preferably transparent and may be coloured or colourless.

A light source 32 is arranged in the lower part of the housing, most preferably under the viewing bed 18. The details of the light source 32 are described further below.

Behind the viewing screen 14 is arranged a light modifying means 24 which preferably comprises first and second light modifying components. In the preferred example as illustrated, the respective light modifying components comprise a rear reflector 26 and a dynamic light modifying component 28, in particular a flame effect element. The rear reflector is mounted on or proximate the rear wall 12A of the housing 12 and may preferably comprise a sheet of shiny - especially mirror finished - material such as a polished metal sheet or a sheet of metallised plastic. The rear reflector 26 is preferably, but not essentially, generally planar. Shaped reflectors can be used. For example the rear reflector 26 may be concave or convex or may have an irregularly shaped surface, for example a series of complex curves. In alternative arrangements a reflector, or an additional reflector, may be located elsewhere in the housing than behind the viewing screen 14. For example, a reflector may be placed in a lower part of the housing towards the rear.

The dynamic light modifying component 28 is dynamic in the sense that it operatively moves, or has motion imparted to it, in order to modify the light. The dynamic light modifying component 28 is placed in the path of light from the light source 32 to the viewing screen and most conveniently is arranged immediately in front of the rear reflector 26 and behind the viewing screen 14. The dynamic light modifying component may be reflective and/or transmissive of light. In a preferred arrangement the dynamic light modifying component comprises one or more webs of fabric which have reflective qualities such silk or artificial silk like materials such as certain polyester or nylon materials. In one arrangement the dynamic light modifying component comprises a single web of such reflective material suspended behind the viewing screen 14 and including a plurality of holes or apertures which may conveniently extend primarily up and down the web and may approximate to flame shapes. Light reflected by the rear reflector thus passes through the apertures and onto the viewing screen. The apparatus 10 in this arrangement further comprises a blower 30 arranged in the lower part of the housing 12 and arranged to direct a current of air onto the web of material to cause the web of material to billow. Thus, apparent motion is afforded to the image on the viewing screen caused by light passing through the apertures in the web of material falling on the viewing screen 14.

A more preferred arrangement as illustrated in particular in Figures 2, 3 and 4 behaves similarly. In this case the apertured web of billowing material is replaced by a plurality of strips or flags 28a of material having reflective qualities such as silk or artificial silk like materials. The strips 28a are attached to suitable parts of the housing at the upper and lower ends and arranged so that they hang loosely in front of the rear reflector 26 and behind the front screen 14. Preferably the respective ends of the strips 28a are twisted with respect to one another, through about 90°. Again, a blower 30 is arranged in the lower part of the housing 12 and arranged to direct a current of air onto the strips 28a to cause the strips 28a to billow or flutter in a manner which is perceived to be essentially random. Light from the light source 32 is reflected by the moving strips 28a onto the viewing screen 14 and also light reflected by the rear reflector 26 may be modified by passing through the constantly changing gaps between the strips 28a. This construction results in an effective simulation of flames in the viewing screen 14. Light source 32 is arranged in a lower part of the housing 12 so that it can illuminate both the viewing bed 18 and the light modifying means 24. Preferably the light source 32 is arranged below the viewing bed 18, although other locations are possible, for example with the assistance of suitably placed baffles and mirrors to direct the light from the light source to the viewing bed 18 and light modifying means 24. The light source may comprise a conventional incandescent light bulb. Halogen bulbs or LEDs may alternatively be used. One or more light sources 32 may be provided. A particularly preferred construction includes two light sources 32.

At least one at least partially light transmitting member 34 having optically differentiated regions is mounted immediately adjacent each light source 32. The optically differentiated regions are primarily regions of different colour, but may also include regions having a different surface relief (non-planar surface) to refract light passing through the member 34 in different ways, or may include shaded or opaque regions, or combinations of these. The member 34 is arranged to move with respect to the light source 32 so that the light from the light source 32 may be affected by the member 34 in different ways at different times. The member 34 may take various forms. For example the member may comprise a strip of material having the optically differentiated regions and formed into a loop which is caused to move around the light source 32. Alternatively, the member 34 may be in the form of a cylinder within which the light source 32 sits. Preferably, and as illustrated, the member 34 takes the form of a disc 36 arranged directly above the light source 32, optionally at an angle to the horizontal. In a preferred arrangement two discs 36 are provided above two respective light sources 32. Each disc 36 is divided into a number of segments 36a, 36b, 36c, 36d, 36e, 36f etc. Each segment 36n is optically differentiated from its neighbours. Thus in a preferred arrangement the segments 36n have different colours, for example red, green, blue, pink, orange purple. Each disc 36 is driven to rotate about is axis 38 by a motor 40. Stepper motors are preferred since the enable the rotational position of the disc 36 to be controlled with a high degree of accuracy.

An alternative arrangement of the at least partially light transmitting member 34 is shown in Figure 5. In this arrangement, the motor 40, axis 38 and light source 32 are arranged as described above. The at least partially light transmitting member 34 comprises a disc portion 36' which may be substantially the same as the disc 36 described above and a skirt portion 36" which depends from the disc portion 36'. The skirt portion 36" preferably also includes optically differentiated regions in the same way as segments 36n described above. Thus, the skirt portion 36" preferably includes regions of different colour but may also (or alternatively) include regions having a different surface relief (non-planar surface) to refract light passing through the skirt 36" in different ways, and shaded or opaque regions, or combinations of these.

When the apparatus 10 of the invention if operational, light from the light source passes through and is modified by the member(s) 34. Some of the modified light falls on the underside of the viewing bed whereby the viewing bed 18 is illuminated, and more especially the viewing elements 22 are illuminated. Light having passed through the member(s) 34 also falls on the light modifying means 24. In the illustrated example, light is reflected by the rear reflector 26 and also by the moving strips 28a and falls onto the rear of the viewing screen 14 to provide a user perceptible image in the screen.

Thus, according to the position of the or each disc 36, a different effect is optical obtained in the viewing 14 screen and/or the viewing bed 18. The optical effect seen in the viewing screen 14 and the viewing bed 18 can change colour or form, depending which optically differentiated region 36n of the disc(s) 36 lies above the light source. This effect is particularly apparent and pleasing where the viewing bed 18 comprises a transparent or translucent supporting substrate 20 (especially a glass panel) and where the viewing elements 22 comprise transparent glass or plastic beads. Glass beads have the property of reflecting and breaking up the light incident on them, which adds interest to the optical effect. Where the optical effect in the viewing screen 14 is a simulation of flames, the flames can be made to change in colour and intensity which adds both realism and interest. If fact, in order to obtain a pleasing effect, it is not essential for the flames to be especially realistic. The ever-changing nature of the image in the screen 14 is pleasing in itself.

In an especially preferred form of the apparatus 10, a control means 44 is included which is operable to control the speed of rotation and or position of the discs 36. The control means 44 can be programmed to control the movement of the discs 36 in a predetermined sequence which may, for example, appear to a user to be random. Alternatively, and preferably, the control means 44 may be operable by a user so that the user may select the speed of rotation and/or position of the discs 36. For example a user-operable control panel 42 may be provided at a suitable location on the housing 12 which control panel co-operates with the control means 44 to vary the speed of rotation and/or position of the discs 36. In another variation, a remote control handset 46 may be provided which the user may use to communicate with the control means 44 (via a receiver 42') to vary the speed of rotation and/or position of the discs. Thus, a user may set a particular colour or combination of colours for the optical effects in the viewing screen 14 or viewing bed 18 and may also adjust the rate of change of such effects. Thus, if a user favours a particular colour, the user can position the appropriately coloured segment 36n above the adjacent light source 32. Preferably, where the apparatus 10 includes more than one disc 36, the user may use the control means 44 (42, 46) to adjust the rotational position or speed of rotation of each disc 36 independently.

The apparatus 10 may (but does not essentially) include a heat source. Typically, a fan heater 48 may be arranged to expel heated air from beneath the canopy 12G.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", means "including but not limited to", and is not intended to (and does not) exclude other moieties, additives, components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

Claims

1. Apparatus for providing an optical effect comprising:

(i) a housing (ii) a light source mounted in the housing

(iii) a viewing screen in which the optical effect may be observed

(iv) light modifying means arranged behind the viewing screen in the path of light from the light source to the viewing screen

(v) at least one at least partially light transmitting member having optically differentiated regions, said member being disposed in the path of light from the light source to said light modifying means; and (vi) means for moving said light transmitting member with respect to the light source.

2. Apparatus for providing an optical effect comprising:

(i) a housing

(ii) a viewing bed observable by a user from the front of the housing (iii) a light source disposed below the viewing bed

(iv) at least one at least partially light transmitting member having optically differentiated regions, said member being disposed in the path of light from the light source to said viewing bed; and

(v) means for moving said light transmitting member with respect to the light source.

3. Apparatus as claimed in claim 2 further comprising

(vi) a viewing screen in which an optical effect may be observed, and

(vii) light modifying means arranged behind the viewing screen in the path of light from the light source to the viewing screen, and wherein said at least one at least partially light transmitting member is also disposed in the path of light from the light source to said light modifying means.

4. Apparatus for providing an optical effect comprising:

(i) a housing (ii) a light source mounted in the housing

(iii) a viewing screen in which an optical effect may be observed (iv) a viewing bed observable by a user from the front of the housing

(v) light modifying means arranged behind the viewing screen in the path of light from the light source to the viewing screen,

(vi) at least one at least partially light transmitting member having optically differentiated regions, said member being disposed in the paths of light from the light source respectively to said light modifying means and said viewing bed; and (vii) means for moving said light transmitting member with respect to the light source.

5. Apparatus as claimed in claim 1 , 3 or 4 wherein the light modifying means comprises first and second light modifying components.

6. Apparatus as claimed in claim 2, 3 or 4 or claim 5 when dependent on claim 3 or 4 wherein the viewing bed comprises an at least locally translucent substrate shaped and coloured to resemble burning fuel.

7. Apparatus as claimed in claim 2, 3 or 4 or claim 5 when dependent on claim 3 or 4 wherein the viewing bed comprises a supporting substrate and discrete viewing elements arranged on the supporting substrate.

8. Apparatus as claimed in claim 7 wherein the substrate is a frame or other openwork construction.

9. Apparatus as claimed in claim 7 wherein the substrate is a substantially opaque supporting web including a plurality of light transmitting apertures.

10. Apparatus as claimed in claim 7 wherein the substrate comprises a web of substantially transparent material.

11. Apparatus as claimed in claim 10 wherein the substrate comprises a body of glass or transparent plastic.

12. Apparatus as claimed in any of claims 7 to 11 wherein the discrete viewing elements comprise fuel pieces or simulated fuel pieces.

13. Apparatus as claimed in any of claims 7 to 11 wherein the discrete viewing elements comprise pieces of translucent or transparent material.

14. Apparatus as claimed in claim 13 wherein the viewing elements comprise pieces of glass.

15. Apparatus as claimed in claim 13 or 14 wherein the viewing elements comprise glass beads.

16. Apparatus as claimed in claim 5 wherein the first light modifying component comprises a reflector mounted behind (with respect to the viewing screen) the second light modifying component.

17. Apparatus as claimed in claim 5 or 16 wherein the second light modifying component comprises a dynamic light modifying component.

18. Apparatus as claimed in 17 wherein the dynamic light modifying component comprises at least one at least partially reflective web of material suspended within the housing and means for providing a flow of air to the web of material whereby the web of material is caused to billow or flutter.

19. Apparatus as claimed in claim 18 comprising a plurality of strips of said material.

20. Apparatus as claimed in claim 18 comprising a web of said material including a plurality of light transmitting apertures.

21. Apparatus as claimed in claim 1 or any of claims 3 to 20 wherein the optical effect which may be observed in the viewing screen simulates or resembles flames.

22. Apparatus as claimed in any preceding claim wherein the means for moving said light transmitting member with respect to the light source includes one or more stepper motors.

23. Apparatus as claimed in any preceding claim wherein the or each at least partially light transmitting member having optically differentiated regions comprises a substrate having differently coloured regions.

24. Apparatus as claimed in any preceding claim wherein the or each at least partially light transmitting member having optically differentiated regions comprises a substrate having a non-planar surface.

25. Apparatus as claimed in any preceding claim wherein the at least partially light transmitting member having optically differentiated regions comprises a substrate having opaque or darkened regions.

26. Apparatus as claimed in claim 23 wherein the or each at least partially light transmitting member having optically differentiated regions comprises a substrate having differently coloured regions and one or more of regions having a non- planar surface, opaque regions and darkened regions.

27. Apparatus as claimed in claim 23, 24, 25 or 26 wherein the substrate is a substantially planar disc operatively rotated about its axis.

28. Apparatus as claimed in any preceding claim further comprising user-operable control means operable to control the movement of the at least one at least partially light transmitting member having optically differentiated regions.

29. Apparatus as claimed in claim 28 when dependent on claim 27 wherein the control means is operable to control the speed of rotation of the disc.

30. Apparatus as claimed in claim 28 when dependent on claim 27, or as claimed in claim 29, wherein the control means is operable to control the rotational position of the disc.

31. Apparatus as claimed in claim 28 wherein the apparatus comprises a plurality of at least partially light transmitting members having optically differentiated regions and the control means is operable independently to control the movement of said light transmitting members.

32. Apparatus as claimed in claim 31 wherein the means for moving said light transmitting member with respect to the light source includes a stepper motor for each respective at least partially light transmitting member and the control means is operable to control each stepper motor independently.

33. Apparatus as claimed in claim 31 or 32 wherein the at least partially light transmitting members having optically differentiated regions comprise discs as defined in claim 23.

34. Apparatus as claimed in claim 33 wherein the control means is operable to control the speed of rotation of the respective discs.

35. Apparatus as claimed in claim 33 or 34 wherein the control means is operable to control the rotational positions of the respective discs.

36. Apparatus as claimed in claim 1 , 2 or 4 substantially as hereinbefore described with reference to any of Figures 1 to 4.