GB2137336A - Electrical illumination devices for simulated fires - Google Patents

Abstract

An electrical illumination device comprises a light source 1, light from which is arranged to pass through two flat translucent or transparent substantially parallel plates 2, 3. Each plate has opaque segments disposed radially about its centre and the plate 2 is in the form of a disc which is rotatably mounted about its central axis and operatively connected to drive motor 4 therefor. The device incorporates one or more viewing screens 5, 6 and an electronic circuit operable to control the output level of the light source. Viewing screen 5 is a metal plate and screen 6 is a layer of pieces of broken lead crystal. <IMAGE>

Description

SPECIFICATION Electric illumination devices This invention relates to electrical illumination devices suitable for use with simulated fires. The object of the invention is to provide an optical projection deviceforthe generation of a flame-like lighting effect. Devices in accordance with this invention may be used in conjunction with, for example, an arrangement of pieces of broken coloured lead crystal or other materia Is to produce a realistic and attractive fire effect for use for example in an electricfiregrate.

Overa number of years various devices for produc- ing a flame-like effect for incorporation in electric or gas heaters or in firegrates have appeared on the market so incorporated. A certain degree of realism has been achieved but the effect of "liveliness" and "dancing flames" overthe material which forms the "fuel" has to some extent been spoiled either by the "flames" being restricted to small portions of the "fuel", by obvious repetition of the "flames", by absence of real variation in the background level of illumination or by some combination ofthe aforementioned in some degree.

It is an aim ofthe present invention to produce a more realistic effect of changing moving "flames" of constantlyvarying lightintensityoverthe major portion of the "fuel" in a simulated fire.

According to the invention there is provided an electrical illumination device comprising a light source, lightfrom which is arranged to pass through two flat translucent ortransparent substantially parallel plates, each having opaque segments disposed radially about its centre and one of the plates being in the form of a disc which is rotatably mounted about its central axis and operatively connected to drive means therefor, the device incorporating one ormore viewing screens and an electronic circuit operably to control the output level of the light source.

In operation the clear and opaque segments on the fixed and moving plates interact with the transmitted lightfrom the light source to produce moving moiré patterns on the viewing screens by transmission or reflection,theform ofthe patterns being controlled by the disposition oftheclearand opaque segments so asto produce simulated varied and moving flames. At the same time the electronic circuit reads a pattern of reflective areas on the rotating disc and uses this reading to control and vary the light source output, thus enhancing theflame-like effect.

In one embodiment of the invention the electric illumination device forms part of an electricfiregrate which has a broken crystal type translucentfuel effect placed in front of and below a reflective backplate with the fuel effect and the backplate constituting the viewing screens.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 of the accompanying drawings shows in diagrammatic vertical cross-section an electric illumination device constructed in accordance with the present invention.

Figure 2 shows by way of example and in di agrammaticcross-section an electric firegrate incorporating an electric illumination device constructed in accordance with the present invention. Atangential flowfan heater is also shown incorporated in the fi reg rate.

Figure 3 illustrates diagrammatically the same firegrate as that shown in figure 2 but including only the electric illumination device and excluding the heater.

Figure 4 illustrates in diagrammaticform one example of a fixed and a rotatable translucent plate with the opaque areas shown hatched.

Figure shows diagrammatically the electronic circuit which is incorporated into the electricillumina- tion deviceforthe control ofthe light source.

Figure 6shows diagrammatically a further electronic circuit for incorporation into the electrical illumination device as an alternative to the circuit in fig. 5.

Figure 7(1) and (II) shows diagrammatically the relative dispositions of electronic sensor, rotatable plate and light source when the light beam is to be interrupted (I) by direct blocking and (II) by nonreflection.

Figure8shows in diagrammatic form and by way of illustration, one example of a portion ofthe rotatable translucent disc on which two patterns of differing reflectivity are superimposed.

Referring to figure 1 ofthedrawings. Lightfromthe light source 1,which may be a tungsten filament bulb passes through the translucent plates 2, 3, on the underside of which are superimposed 13, 14, radial patterns of opaque segments (as shown in fig. 4).

Typical light paths are shown by the broken lines 1 a, 1 b. Viewing screen 5, is constituted by a metal plate which would in certain embodiments of the invention be formed by the backplate of an electricfiregrate in which the electric illumination device is installed.

Viewing screen 6, is a layer of pieces of broken lead crystal supported by plate 3.

The rotatabletranslucent plate 2, is madetoturn by means of a small geared motor4, and moving moire patterns, formed on the screens by the interaction of the clear and opaque areas with light from the light source, are viewed from the general direction of the arrows la, 1 b. As the rotatable plate turns a reflective pattern which is superimposed on its periphery is read serially by an opto-electronic switch 7, which forms part of a circuit. (this circuit is shown in fig. 5 but has been omitted from fig. 1 forthe sake of clarity and may be mounted in any convenient position on the baseplate which carries the components which make up the electric illumination device).The electronic circuit is so arranged asto varythe amountof light output from the light source in response to the varying reading from the opto-electronic switch.

Figure 2 shows in diagrammatic vertical crosssection an embodiment of the electric illumination device in an electric firegrate. Thefiregrate frame 8, supportsatangentialflowfan heater 10,with air blown frontwards as shown by the broken line 1 0a.

The electric illumination device is convenientiy mounted abovethefan heater. Avertical addition 9, is fixed to the translucent plate 3, and a vertical addition 6a, is fixed to the viewing screen 6, to enhance the appearance of the effect and to conceal the mechan ism from view. A translucent viewing screen is formed bythe layer of broken crystal 6, 6a, and reflective viewing is provided bythebackplateofthefire 5, which may have a polished or light-diffusing finish.

Typical light paths are indicated by broken lines 1 a, 1 b, 1c.

Figure 3 shows in diagrammatic vertical crosssection an embodiment of the electric illumination device in an electricfiregrate (similarto that shown in fig. 2) butwithoutthe inclusion of a heater. In this arrangementthevertical portion ofthetranslucent viewing screen 6a, and of its support 9, is extended in a downward direction to cover the heateraperture.

The electric illumination device is placed in a lower positionwithinthefiregrate in orderto provide light coverage ofthe extended translucent viewing screen.

In orderto produce effective varying moire patterns the gap between the fixed plate 3, and the rotatable plate 2, should not exceed two centimetres. In the electric illumination device shown in fig. 1, and its embodiment as shown in fig. 2, it is convenientto use the fixed translucent plate 3, to function also as a supportforthe broken crystal screen 6. However, since the translucent plate 3, must be lowered in the embodiment shown in fig. 3, an additional translucent plate 3b, without superimposed opaque segments is usedtosupportthe broken crystal viewing screen 6.

In figures 1 to 3 (above) the preferred choice and arrangement of broken crystal is a mixture of pieces of crystal of various shades including self-coloured clear, amber, ruby and black, in differing depths of colour, with the lighter shades predominating. The size of individual pieces of crystal mayvaryfrom one centimetre to ten centimetres in their maximum Dimensions. A 'bed' of pieces ofcrystal may be formed by attaching individual pieces to the translucent plate or plates which supportthem by use of an adhesive. Separate loose pieces of crystal maythen be placed on the fixed 'bed' to enhance the appearance. It may be convenient in certain embodiments of the invention to use a material otherthan broken crystal.

For example, a complete shell of simulated fuel may be formed in one piece from pressed crystal orfrom a translucent plastic material.

Figure 4 shows in plan view and by way of illustration one example of the fixed translucent plate 3, and one example ofthe rotatable translucent plate 2,togetherwiththe patterns of opaque segments which are superimposed on the plates. The opaque portions are represented by the shaded areas 13 etc., and 14 etc. The fixed translucent plate 3, is shown as rectangular in shape since it fits within the firegrate opening which would be conveniently of rectangular form. The shape may be modified howeverto fit firegrate openings which are of irregular form. The opaque and clear areas on the fixed plate 3, are delineated by a series of lines which run from the centre of the plate outto its perimeter. In a preferred arrangementthe lines are so arranged thatthe angles formed by adjacent lines are approximately equal.

Angle size is adjusted to give optimum moire effect and opaque and clear areas are formed alternately on the plate by the superimposition of an opaque material such aspaintwhich maybeapplied by,for example, the silk screen process. The rotatable translucent plate 2, is circular in form with opaque and clear areas which are delineated by a series of lines which runtangentiallyfrom a small circle which is concentric with the plate outto the periphery ofthe plate, the diameter ofthe small circle being approximately one twelfth of the diameter of the circular plate. The angles formed by the lines are randomly varied and alternate areas are given an opaque superimposition (as with plate 3, above).

In figures 1 to 3 above the rectangular plate 3, is disposed so that its forward facing edge is depressed, setting the plate at an angle which may be fifteen degrees to the horizontal. The circular plate 2, is disposed belowthe rectangular plate so thattheir plane surfaces are parallel and approximately one centimetre apart and so that a line through the centre ofthe circular plate, at rightanglesto the plate, intersects the centre of the pattern which is superimposed on the rectangular plate (see fig. 1, 17.). If the rotatable plate when viewed from a face-on position is to rotate in a clockwise direction (as shown in fig. 4, 15.),thetangents to the small inner circle are taken in a right-hand clockwise mode as illustrated. The reverse also applies.Sheet glass is a preferred material for both fixed and rotatable translucent plates and this may be ofthe plain or'obscure'type, although various combinations of glass and/or othertranslucent mate- rials are possible. It has been found thatthe use of a light-coloured or reflective material, for example silver paint, may be used for the formation of the opaque areas on the rotatable plate in which case the opto-electronicswitch may be activated by the reflective opaque areas eliminating the needfora further pattern. The opaque areas on the fixed translucent plate may be superimposed in a shade of colourwhich enables them to blend in with the pieces of coloured crystal when the device is used in an embodiment such as that shown in fig. 2,wherethe broken crystal 6, is mounted directly on to the translucent plate 3.In certain cases it has been found that an improved visual effect is obtained if the outer extremities ofthe superimposed pattern on the fixed plate are 'broken' bythe removal of small areasfrom each segment of pattern as illustrated in fig. 4,16.

Variation may be introduced by altering the angle at which the opaque segments on the fixed and rotatable plates appearto intersect when viewed, and more particularly for example, by altering the radial position ofthe opaque sections on the rearward facing portion of the fixed plate so that the 'flames' viewed on the rear part ofthe translucent screen have a different apparent motion to those viewed on the front part.

It has been found that an optimum moire effect to give a realisticflame-like appearance on both backplate and translucent screen with the embodiments as illustrated in figures 1 to 3, may be achieved when the number of opaque areas on the rotatable and fixed translucentscreens is approximatelythe same, and where the number of opaque areas on the rotatable plate is greaterthan the peripheral speed of the plate, measured in centimetres per second, by a factor of between three and five, and where the number of opaque segments is approximately equal to twice the diameter ofthe disc measured in centimetres.

In certain embodiments ofthe invention the fixed and rotatable plates may be placed so that they lie in a horizontal plane rather than being tilted. Additionally, the position of the light source or sources may be altered so that an all-round effect may be obtained.

This modification could be applied for example to a 'free-standing'fire effect where no 'formal'firegrate is required.

It is not necessary thatthe geometric centres of the fixed and rotatable plates should lie on the axis which is at right angles to the plane of the plates provided thatthe geometric centres ofthe superimposed patterns lie onthis axis (seefig.1, 17.) Figure 5 shows diagrammatically a preferred exam pleofan electronic circuit as referred to in the description offigure 1, and or whichtheopto- electronic switch 7, forms a part. Power supplied at 240 volts flows through the bulb 19, and the resistor 20 to cause the bulb to light in a 'low illumination mode', atthe same time lowvoltagefrom the transformer is suppliedtothe electronic components.The light emitting diode ofthe reflective opto-electronic switch 7, is energised and emits infra-red radiation which is reflected by a segment of reflective opaque material figs. 4 and 5, 13, on the rotatable translucent plate (figs 1-4,2). Reflected light is received by the light sensitive transistor of the opto-switch 7, and a current is passed.

Current produced bythe light sensitivetransistor is amplified by a transistor 24, and the resultant amplified current triggers the triac 21, allowing a high voltage currentto flow through the trial and the bulb, by-passing the resistor 20, as resistor20, and triac 21, are connected in parallel. Thus full voltage is applied to the bulb setting it in a 'high illumination mode' for the duration ofthe passage of the moving reflective segmentfigs. 4 and 5,13, across the 'window' ofthe opto-switch. The translucent plate is made to turn continuously by the small motorfig. 1,4, and as it does so the opaque reflective segment moves away from the window and a translucent area takes its place.

Reflection nowstopsand as the lightsensitive transistor is receiving no signal it ceases to pass currentthus switching offthetriac and returning the bulb to its 'low illumination mode'. As a succession of reflective and non-reflective areas on the rotatable plate passes before the window of the opto-switch a series of high and low 'illumination modes' is produced, the duration of each high and low being controlled bythewidth of successive opaque and clearsegments of the rotatable plate. Since the width ofthe segments is varied randomly, a train of pulses of highand lowillumination of randomlyvarying duration is produced.

A resistor 22, and a capacitor 23, in series, are connected in parallel with the triac to function as a radio frequency interference suppressor.

The electronic circuit as described above may be modified in different embodiments of the invention and to suit different situations. It may, for example, be desirable to replace the opto-switch by a simple light sensitivetransistorwhich is activated by the lightfrom the bulb. Alternatively the opaque segments on the rotatable plate may be formed from a ferrows material with a hall effect switch being used in place of an opto-switch. It has been found that in the embodiments shown in figures 2 and 2 above, two bulbs ofthe type known asfireglow are suitable for provision of illumination with an average size electric fireg rate, although the circuit has the capability of controlling a multiplicity of bulbs.It has further been found that with a random arrangement ofwide and narrow opaque segments as may be indicated in fig. 4, 13, where the number of segments is greater than the peripheral speed of the plate, measured in centimetres per second, buy a factor of between three and five, and where the number of opaque segments is approximately equal to twice the diameter ofthe disc measured in centimetres, no obvious repetition of lightvariations or moire patterns is discernible.

Referring to Figure 6 is has been found that the use of a full wave lamp dimmer circuit operating on the phase-shiftprinciple,fig.6,26, permits a greater variety of illumination level, atthe same time obviating the need for large wattage resistorfig. 5, 20, thus removing a source of unwanted heat. In Fig. 6the opto-electronic switch is shown as two separate components, light sensitive transistor7a, and light emitting diode 7b, in orderthat alternative dispositions of sensor and light source, relative to the rotatable disc, may be employed in differing configurations ofthe embodiment ofthe invention, and also that optimum lighting effect may be achieved.

The circuit shows two light sources which may be used for sensoractivation,the light emitting diode 7b and the bulb or bulbs 19.The lower level of illumination i.e. with the sensor not operative, is set by variable resistor 25.

Figure 7 shows two optional ways in which the superimposed pattern on the rotatable disc may be read. In Fig. 7 (I) the light source "L"which operates upon the sensor is placed so that the outer lands of the rotatable disc pass between the light source and the sensor7a thus producing an on-off action as the light beam is restored and broken sequentially as the disc 2, rotates and allows clear and opaque areas, 13, to alternately pass or blockthe beam. In Fig. 7 (it) a reflective mode of operation is shown. As the rotatable disc, 2, rotates, alternate reflective, 13, and non reflective surfaces are presented to the beam of light from light source "L".With reflective surface in a position as shown in Fig. 7 (it) the sensor is operated upon by the beam of reflected light until the reflective area has passed as the disc rotates, the beam then being broken until restored by the passage ofthe next reflective area. In the case of 7(1) and 7 (it) above, the level of illumination of the bulbs is increased when the sensor is operated upon by the beam of light. A fragment only ofthe disc is shown rotating as indicated by the arrow, 15.

Figure 8 shows a further preferred modified arrangement of part of the reflective pattern 4, 13, which is superimposed upon the rotatable plate 2, in theform of segments, 13.Afurther, more highly reflective pattern, 13a, in the form ofsmaller segments is superimposed upon pattern 13 in a random fashion, thus giving a resultant pattern of segments posessing two levels of reflectivity. As the rotatable discturns, the pattern is read bythe sensor as described in the notes on Fig. 7 (it) butwith an additional variation.

When there is no reflection ofthe light beam the reading is "zero" and the level of illumination of the bulb/s is a base level which is set by adjustment ofthe variable resistor, 25. When a "standard" reflection is read from the first superimposed pattern, the level of illumination ofthe bulbs is increased to a substantial fraction of full output. When however, the very highly reflective second superimposed pattern 1 3a, is read, it is arrangedthatthe sensor is so energisedthatfull output of illumination from the bulbs is obtained. Thus the circuit as described in Fig. 6, in conjunction with the configuration of light source and sensor as described in Fig. 7 (it) togetherwith a rotatable plate, 2, carrying an additional superimposed pattern as described in Fig. 8 in an assembly substantially as described in Fig. 1, enables a multiplicity of continuous variations of the level of luminosity of the bulbs to be achieved, giving a more interesting and varied effect.

Claims (29)

1. An electrical illumination device comprising a light source, light from which is arranged to pass through two flat translucent or transparent substantially parallel plates, each having opaque segments disposed radially about its centre and one of the plates being intheform of a disc which is rotatably mounted about its central axis and operatively connected to drive meanstherefor,the device incorporating oneor more viewing screens and an electroniccircuitoper- able to control the output level ofthe light source.

2. An electrical illumination device as claimed in Claim 1 in which the fixed and rotatable plates are of glass with the rectangular fixed translucent plate having a superimposed pattern which is delineated by a series of lines which run from a point nearthe geometric centre ofthe plate outto its perimeter, the angles between adjacent lines being approximately equal and arranged so as to give optimum Moire effect.

3. An electrical illumination device as claimed in Claims 1 or 2 in which the rotatable plate is circular in form with a superimposed pattern which is delineated by a series of lines which run tangentially from a small circle, concentric with the plate, outto the periphery of the plate, the small circle having a diameter approximately one twelfth the diameter of the plate, and angles between adjacent lines being randomlyvaried.

4. An electrical illumination device as claimed in Claim 3 in which the lines delineating the pattern on the rotatable disc are so drawn that when viewed from a face-on positon in the case of a disc arranged to rotate in a clockwise direction,the tangents to the small inner circle are drawn from the circle in a right hand clockwise mode, and in the case of a disc arranged to rotate in an anti-clockwise direction are drawn in a left hand anti-clockwise mode.

5. An electrical illumination device as claimed in any preceding claim in which the superimposed pattern is constituted byan opaque material which is arranged so asto presentalternateopaque and translucent areas in the form of segments.

6. An electrical illumination device as claimed in any preceding claim in which the fixed translucent plate is disposed so that its forward facing edge is depressed, so setting the plate at an angle to the horizontal with the rotatable plate disposed below the fixed plate so that their plane surfaces are approximately parallel and a small distance apart, and in such position that a line through the centre of the rotatable plate at rightanglesthereto intersects approximately the centre of the pattern which is superimposed on the fixed plate.

7. An electrical illumination device as claimed in Claim 6 in which the superimposed pattern is produced by the application of a reflective opaque material to the glass.

8. An electrical illumination device as claimed in Claim 7 in which a second pattern of opaque reflective areas of lesser area than the first pattern but possessing greater reflectivity is superimposed upon the first pattern, on the rotatable disc.

9. An electrical illumination device as claimed in Claim 8 in which the applied reflective material forms the basis of a pattern which is read serially by electronic means as the rotatabletranslucentdisc turns, the resultant signal being utilised for control of the illumination level ofthe lightsource.

10. An electrical illumination device as claimed in any preceding claim in which the outer extremities of the superimposed pattern on the fixed plate are "broken" bythe removal of small areas from each segment of pattern.

11. An electrical illumination device as claimed in any preceding claim in which the superimposed material on the fixed plate is of a colourwhich blends with the colour of crystal material supported on the plate to the one ofthe said viewing screens.

12. An electrical illumination device as claimed in any preceding claim in which the rotatable plate is turned by a geared electric motor ata speed of between 9 and 15 revolutions per minute and where the number of opaque areas on the plate is greater than the peripheral speed ofthe plate measured in centimetres per second by a factor of between 3 and 5, and the number of opaque areas is greater than the radius ofthe plate in centimetres by a factor of between 3 and 5.

13. An electrical illumination device as claimed in any preceding claim in which the translucent plates or either ofthe translucent plates are composed of a translucent ortransparent plastics material.

14. An electrical illumination device as claimed in any preceding claim in which the fixed and rotatable translucent plates are disposed in a horizontal or approximately horizontal manner.

15. An electrical illumination device as claimed in any preceding claim including afirstviewing screen comprising a substantially vertical metal plate with a reflecting surface and a second viewing screen formed by an arrangement or lumps of broken coloured crystal supported onthefixedtranslucent plate.

16. An electrical illumination device as claimed in Claim 15 in which the lumps of broken crystal are supported on a translucent plate without a superimposed pattern, which plate is disposed in a position above the plate on which said pattern is superimposed.

17. An electrical illumination device as claimed in Claims 15 or 16 in which the translucent crystal supporting plate has a downward extension from all or part of its perimeter in the form of a "skirt".

18. An electrical illumination device as claimed in any of Claims 15 to 17 in which the pieces of broken crystal are replaced bya complete shell either of crystal or of a translucent plastic material.

19. An electrical illumination device as claimed in any one ofthe preceding claims wherein the light source comprises of one or more tungsten filament bulbs.

20. An electrical illumination device as claimed in Claim 19 wherein the supply of powerto the or each bulb is controlled by electronic means so that the supply of power isvaried by the switching in and out ofthe lamp circuit of an electrical resistance.

21. An electrical illumination device as claimed in Claim 19 where the supply of powerto the or each bulb is controlled by one or more electronic lamp dimmer circuits operating on the phase-shift principle.

22. An electrical illumination device as claimed in Claims 20 or 21 wherein the power supply to the or each bulb is controlled by an electronic sensor which is operated upon either by the lightfrom the bulbs or by lightfrom a light emitting diode, the beam interruptions produced when successive clear and opaque areas on the rotatable disc pass the sensor acting upon the sensor and associated circuit to produce a variable output.

23. An electrical illumination device as claimed in any of Claims 1 to 21 wherein the superimposed pattern on the rotatable plate embodies a ferrous material which is read buy a magnetically actuated electronic sensor.

24. An electrical illumination device as claimed in any of Claims 1 to 22 wherein a second more highly reflective pattern is superimposed over parts of the opaque reflective pattern on the rotatable translucent disc enabling two levels of reflected lightto act upon the electronic sensorto produce additional variation of lamp illumination.

25. An electrical illumination device substantially as herein described with reference to Fig. 1 of the drawings.

26. Electrical illumination devices substantially as herein described with reference to Figs. 1 and 4to 8 of the accompanying drawings.

27. An electric fire or simulated fire incorporating an electrical illumination device in accordance with any ofthe preceding claims.

28. An electricfireorsimulatedfireincorporating an electrical illumination device substantially as herein described with reference to Fig. 2 or Fig. 3 ofthe drawings.

29. Any novel subjectmatterorcombination including novel subject matter herein disclosed, whether or not within the scope of or relating to the same invention as any ofthe preceding claims.