GB2236845A

GB2236845A - Flame effect simulator

Info

Publication number: GB2236845A
Application number: GB8918470A
Authority: GB
Inventors: Stephen Arthur Hughes Smith; Gordon Thomas Dyos
Original assignee: ELECTRICITY COUNCIL RESEARCH C
Current assignee: ELECTRICITY COUNCIL RESEARCH C
Priority date: 1989-08-14
Filing date: 1989-08-14
Publication date: 1991-04-17
Anticipated expiration: 2009-08-14
Also published as: GB8918470D0; GB2236845B

Abstract

A flame effect simulator comprises a light source (1) arranged to direct a collimated beam (3) of light along an optical axis, a first light deflecting element (8) in the form of a disc located in the path of the beam and means (10) operable to rotate the first deflecting element such that a portion of the element upon which the beam is incident moves transversely with respect to the optical axis, the direction of movement being such that deflected light directed onto a display area (5) provides a visual effect including upwardly moving features. A second static deflecting element (6) is also provided. The deflecting elements (6, 8) each comprise at least one patterned surface comprising indentations and/or projections of irregular geometry and the width of the beam incident on the deflecting elements measured in at least one direction normal to the optical axis is of the same order of magnitude as the width of the indentations and/or projections. The simulator is suitable for providing domestic heating appliances with a display simulating a log or coal fire. <IMAGE>

Description

'FLAME EFFECT SIMULATOR" This invention relates to apparatus for simulating the visual effect of flames and in particular but not exclusively a flame simulator of a domestic heating appliance.

It is known to provide domestic heating appliances with a flame simulating display. It is an object of the present invention to provide apparatus in which the display realistically simulates the flame pattern generated by a coal fire or log fire for example.

According to the present invention there is disclosed apparatus for simulating the visual effect of flames comprising a source of substantially collimated light arranged to direct a beam of light along an optical axis of the apparatus, at least one light deflecting element located in the path of the beam and means operable to move the or at least one of the deflecting elements such that a portion of the element upon which the beam is incident moves in a direction transversely to or at an angle greater than zero with respect to the optical axis, the direction of movement being such that deflected light directed onto a display area provides a visual effect including upwardly moving features, wherein the or at least one deflecting element comprises at least one patterned surface comprising indentations and or projections of irregular geometry and wherein the width of the beam incident on the element measured in at least one direction normal to the optical axis is of the same order of magnitude as the width of the indentations and/or projections.

Preferably the or at least one deflecting element comprises a transparent plate through which the beam is transmitted and having at least one patterned surface comprising a smoothly undulating surface with dimples which appear irregular at the scale of the incident beam width. The term smoothly undulating in the present context means that the profile of the surface as viewed in section through the plate is continuously differentiable as a function of position.

Preferably the apparatus includes projection means comprising at least one lens or mirror arranged to direct deflected light onto the display area.

The optical axis may be folded by means of mirrors or the like in order to make the apparatus compact or to fit the available space for a given application.

The display area may comprise a translucent screen whereby the visual effect of flames is viewable as light transmitted and scattered by the screen.

Advantageously the projection means includes a first rod lens oriented so as to broaden the beam in a substantially horizontal direction.

Advantageously the projection means comprises at least one further rod lens oriented so as to broaden the projected beam in a substantially vertical direction.

Preferably the projecting means comprises a first further rod lens positioned such that substantially all of the light transmitted through the deflecting elements passes through the first further rod lens such that the beam is broadened in the vertical direction and further comprises a second further rod lens positioned to upwardly deflect part of the beam transmitted through the first further rod lens onto an upper illuminated area of the display area, the remainder of the beam being directed onto a lower illuminated area of the display area separated from the upper portion by a substantially un-illuminated area. The light source may be arranged to project a substantially horizontally extending light beam, the first rod lens being arranged substantially vertically in the light beam and the first and second further rod lenses being arranged horizontally.

Preferably the apparatus comprises means rotating the or at least one of the deflecting elements about a rotation axis substantially parallel to and spaced from the optical axis. The apparatus may also include means for varying the speed of the illuminated portion of the deflecting elements relative to the optical axis. In the case of a rotated deflecting element the speed may be varied either by adjusting the separation between the optical axis and the rotation axis or by adjusting the rotation speed at which the element is driven.

The light source may conveniently be a laser.

Conveniently a solid state laser may be used. Other types of collimated light source may be used such as a point source or near point source of high intensity light coupled to associated optics for producing a collimated beam.

Multiple sources of the same or different type may be used separately to produce multiple effects or the sources may be combined to produce a more intense image.

A particular embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawings of which: Figure 1 is a schematic plan view of the apparatus in accordance with the present invention; and Figure 2 is a schematic side view of the light deflecting elements and rod lenses of the apparatus of Figure 1.

In Figure 1 apparatus 20 has a light source 1 comprising a helium neon laser and a plane mirror 2 which direct a narrow collimated light beam 3 onto a first deflecting element 6. In Figure 1 the light beam 3 emergent from the laser 1 is represented schematically as a single solid line coincident with the optical axis 19 of the apparatus 20. The beam 3 however is to be understood as being a collimated beam of finite width. The light beam 3 after reflection from the mirror 2 extends horizontally towards the lower part of a display area 5 in the form of a vertical translucent screen.

The first deflecting element 6 comprises a glass plate having patterned surfaces. The glass plate is specified as being "dimpled window" glass of 3.5mm approximate thickness. The surface patterns are in the form of dimples forming irregular undulations of the same order of magnitude in both depth and width as the width of the incident light beam 3.

Light passing through the first deflecting element is deflected by refraction at each surface of the glass plate to produce a divergent emerging light beam 7 which if viewed by placing a screen in the path of the beam would appear as an apparently random pattern of light and shade. The incident beam 3 may in effect be regarded as a bundle of parallel light rays each of which is deflected by an angle depending on the position at which it is incident on the element.

The emerging light beam 7 passes through a second deflecting element 8 in the form of a glass disc mounted for rotation about an axis 9 which extends parallel to and spaced from the optical axis.

The second deflecting element 8 is rotated by means of a motor and pulley arrangement 10 such that at any given time a portion 11 which is illuminated by the light beam 7 is upwardly moving. The motor and pulley arrangement 10 is adjustable in position such that the separation between the rotation axis and the optical axis 19 is variable to thereby vary the relative speed between the illuminated portion 11 and the light beam 7.

The second deflecting element 8 is a disc of patterned glass of the same type as that of the first deflecting element 6.

A light beam 12 emerges from the second deflecting element 8 and is passed through a rod lens 4. The rod lens 4 is a glass rod of 15mm diameter and is arranged with its longitudinal axis vertical so that the optical axis 19 passes diametrically through the rod lens so as to broaden the light beam 12 in the horizontal direction. On passing through the rod lens 4 the broadened beam 12 is such that if then projected onto a screen the resulting pattern would be an elongate horizontally extending irregular pattern. The light beam 12 is projected onto the display area 5 by means of first and second further rod lenses 13 and 14 respectively which are both 15mm in diameter glass rods. The positions of the first and second further lenses 13 and 14 is shown in Figure 2 from which it is seen that both lenses extend horizontally and at right angles to the optical axis 19. The second further lens 14 is at a higher position than the first further lens 13 by an amount which is adjustable by a height adjusting mechanism (not shown).

The further rod lenses 13 and 14 spread the light vertically as well as producing upward deflection onto the display area 5. The vertical position of the lenses 13 and 14 is adjusted until all of the light beam passes through the first further rod lens 13 but only part of the light beam transmitted through the first lens is received by the second further rod lens 14. The position of the second further rod lens 14 is adjusted so as to provide further vertical deflection with the result that illumination of the display area is divided into an upper illuminated area 16 and a lower illuminated area 17. An intermediate substantially un-illuminated area 18 is formed therebetween and gives the illusion of a horizontal log or band of coal.

The resultant image appearing on the display area 5 consists in the illuminated areas 16 and 17 of elongate generally vertical light patterns which flicker and move in a similar manner to a series of flames. The rate of movement is determined by the speed of translation of the illuminated portion 11 of the second deflecting element 8.

The second deflecting element 8 comprises a disc with a radius of 5 centimeters. The disc 8 is rotated at 1 revolution per 30 seconds.

The apparatus 20 can produce an effective display on the display area 5 of approximately 1 metre square with the display area located at a range of 0.3 to 3 metres. When incorporated in a domestic heating appliance, the laser, deflecting elements and associated optics are accommodated in a housing (not shown) behind the display area so as to be concealed from view.

The display area may be a screen forming part of the domestic appliance.

The display area may alternatively be an opaque screen such that the visual effect of flames is seen by back scattering from the screen. The opaque screen may be the fire back of a conventional open fireplace where the appliance replaces a conventional grate for the combustion of solid fuel.

The apparatus may alternatively employ other forms of light source provided the light beam is sufficiently intense to produce a visible display and is collimated into a narrow beam. The colour selected for the display will typically be yellow or red where it is required to simulate a visual effect of flames and more than one colour may be provided for increased interest. The rod lenses may be removable to add further variation to the effects which may be displayed. The screen may be tilted if required to distort the projected image. Mirrors may also be included to further shape the image viewed.

Alternative means may be used for projecting the light onto the display area such as mirrors or lenses other than rod lenses.

The deflecting element may alternatively have reflective surfaces such that the incident light beam is reflected by a surface pattern of the element which may conveniently be a sheet of dimpled glass as referred to above in the referred embodiment but to which a reflective coating has been applied to the surface upon which light is incident.

Claims

CLAIMS:

1. Apparatus for simulating the visual effect of flames comprising a source of substantially collimated light arranged to direct a beam of light along an optical axis of the apparatus, at least one light deflecting element located in the path of the beam and means operable to move the or at least one of the deflecting elements such that a portion of the element upon which the beam is incident moves transversely to or at an angle greater than zero with respect to the optical axis, the direction of movement being such that deflected light directed onto a display area provides a visual effect including upwardly moving features, wherein the or at least one deflecting element comprises at least one patterned surface comprising indentations and or projections of irregular geometry and wherein the width of the beam incident on the deflecting element measured in at least one direction normal to the optical axis is of the same order of magnitude as the width of the indentations and/or projections.

2. Apparatus as claimed in claim 1 wherein the or at least one deflecting element comprises a transparent plate through which the beam is transmitted and having at least one patterned surface comprising a smoothly undulating surface with dimples which appear irregular at the scale of the incident beam width.

3. Apparatus as claimed in any preceding claim wherein the display area comprises a translucent screen whereby the visual effect of flames is viewable as light transmitted through the screen.

4. Apparatus as claimed in any preceding claim including projection means comprises at least one lens or mirror arranged to direct deflected light onto the display area.

5. Apparatus as claimed in any preceding claim wherein the projection means includes a first rod lens oriented so as to broaden the beam in a substantially horizontal direction.

6. Apparatus as claimed in any preceding claim wherein the projecting means comprises at least one further rod lens oriented so as to broaden the projected beam in a substantially vertical direction.

7. Apparatus as claimed in claim 6 wherein the projecting means comprises a first further rod lens positioned such that substantially all of the light transmitted through the deflecting elements passes through the first further rod lens such that the beam is broadened in the vertical direction and further comprising a second further rod lens positioned to upwardly deflect part of the beam transmitted through the first further rod lens onto an upper illuminated area of the display area, the remainder of the beam being directed onto a lower illuminated area of the display area separated from the upper portion by an un-illuminated area.

8. Apparatus as claimed in claim 7 wherein the light source projects a substantially horizontally extending light beam, the first rod lens is arranged substantially vertically in the light beam and first and second further rod lenses are arranged horizontally.

9. Apparatus as claimed in any preceding claim further comprising means rotating the or at least one of the deflecting elements about a rotation axis substantially parallel to and spaced from the optical axis.

10. Apparatus as claimed in any preceding claim including means for varying the speed of the illuminated portion of the deflecting element relative to the optical axis.

11. Apparatus as claimed in any preceding claim wherein the light source is a laser.

12. Apparatus substantially as hereinbefore described with reference to and as shown in the accompanying drawings.