Abstract:
Apparatus is provided for projecting light to simulate flames on a screen for use in an electric fireplace with an imitation flame display. The apparatus comprises a hollow cylinder enclosing an interior region, the cylinder being rotatable about an axis of the cylinder and having a sidewall with an exterior surface and a non-reflective interior surface with apertures through the sidewall. A light source in the interior region is operated to cause light to be transmitted through the apertures onto the screen to simulate moving flames when the cylinder is rotated. This arrangement provides an improved imitation flame display on the screen. When incorporated into an electric fireplace, the apparatus provides a pleasing illusion of active, dancing flames adjacent an artificial log set.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to electric heaters with imitation flame displays, and more particularly, to a flame simulating apparatus for generating the appearance of flames in such an imitation fireplace electric heater.  
       BACKGROUND OF THE INVENTION  
       [0002]     There exist electric fireplaces flame simulators in which light from a light source is projected up through a rotating cylinder, through a coloured filter screen and onto a reflective screen. There also exist flame simulators in which light from a light source is reflected from a metallic strip onto a rotating set of coloured metallic strips and then projected through a flame effect element before being finally reflected from a mirror to an observer.  
         [0003]     Our pending Canadian Patent application No. 2,459,788 filed Mar. 5, 2004, the disclosure of which is incorporated herein by reference, discloses a flame simulating apparatus for use in an electric fireplace to project imitation flames onto a screen of the fireplace.  
         [0004]     Our pending Canadian application No. 2.459,849 filed Mar. 5, 2004, the disclosure of which is incorporated herein by reference, discloses a flame simulating apparatus with cooling features for use in an electric fireplace to display imitation flames on a screen.  
       SUMMARY OF THE INVENTION  
       [0005]     The present invention provides an improved apparatus for projecting light to simulate flames on a screen, and an electric fireplace incorporating the apparatus to creates an interesting and pleasing imitation flame pattern visible on a screen within the fireplace.  
         [0006]     Accordingly, the present invention provides apparatus for projecting light to simulate flames on a screen, the apparatus comprising: 
        a hollow cylinder enclosing an interior region, the cylinder being rotatable about an axis of the cylinder and having a sidewall with an exterior surface and a non-reflective interior surface with apertures through the sidewall; and     a light source in the interior region operable to cause light to be transmitted through the apertures onto the screen to simulate moving flames when the cylinder is rotated.        
 
         [0009]     The apparatus is simple in structure for reliable operation and formed using inexpensive parts.  
         [0010]     In a further aspect, the present invention provides an electric fireplace with imitation flames comprising:  
         [0011]     an enclosure;  
         [0012]     an electric heater unit within the enclosure;  
         [0013]     a simulated fuel source within the enclosure; and  
         [0014]     a flame simulation apparatus for generating the appearance of flames, the flame simulation apparatus comprising:  
         [0015]     a light diffusing panel adjacent the simulated fuel source;  
         [0016]     a flame effect mask positioned adjacent the light diffusing panel;  
         [0017]     a hollow cylinder enclosing an interior region, the cylinder being rotatable about an axis of the cylinder and having a sidewall with an exterior surface and a non-reflective interior surface with apertures through the sidewall; and  
         [0018]     a light source in the interior region operable to cause light to be transmitted through the apertures of the cylinder sidewall, past the flame effect mask for projection onto the light diffusing panel for display as simulated moving flames when the cylinder is rotated. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]     Aspects of the present invention are illustrated, merely by way of example, in the accompanying drawings in which:  
         [0020]      FIG. 1  is an exploded perspective view showing an embodiment of the apparatus for projecting light to simulate flames according to the present invention;  
         [0021]      FIG. 2  is a side view, partially in cross-section, of the assembled apparatus of  FIG. 1 ;  
         [0022]      FIG. 3  is a detail view of a panel of the present invention formed with an array of apertures;  
         [0023]      FIG. 4  is an end cross-section view of the assembled apparatus of  FIG. 1  in place within an electric fireplace with a “flame simulation apparatus”; and  
         [0024]      FIG. 5  is a detail view of a flame effect mask shown in the electric fireplace embodiment of  FIG. 4 .  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]     Referring to  FIGS. 1 and 2 , there is shown apparatus  2  for projecting light to simulate flames on a screen according to a preferred embodiment of the present invention. As best shown in its assembled state in  FIG. 2 , the apparatus includes a hollow cylinder  4  enclosing an interior region  6 . The hollow cylinder is rotatable about an axis  8  of the cylinder. As best shown in the exploded view of  FIG. 1 , hollow cylinder  4  is preferably formed as a modular structure that includes a pair of attached panels  122  and  123  which define the sidewall of the cylinder. A mounting frame  20  holds a motor  121  at one end that rotatably drives the hollow cylinder  4  for rotation about axis  8 . A motor drive rod  124  is inserted through frame end bracket  125  to engage with an end plate  126  of cylinder  4 . End plate  126  is connected to another end plate  127  by an array of retaining rods  128 ,  129 ,  130  and  131 . End plate  127  acts as a support for a light source  160 ,  161  positioned within the interior region  6  of the cylinder. Retaining rods  128 ,  129   130  and  131  form a mounting system extending between end plates  126  and  127  for removably securing panels  122  and  123  between the end plates. When secured between end plates  126  and  127 , panels  122  and  123  form the sidewall of cylinder  4  to establish interior and exterior surfaces of the cylinder. The plurality of retaining rods preferably comprise a top flange retaining rod  128 , a bottom flange retaining rod  129 , and a pair of panel backing rods  130  and  131 . The cylinder sidewall is assembled by squeezing together the edges of panels  122  and  123  such that top flanges  140  and  141  on the edges are positioned adjacent a retaining channel  143  in top flange retaining rod  128 . Release of the edges results in the flanges being biased apart by the inherent resiliency of the panels to be retained in channel  143 . Similarly, bottom flanges  144  and  145  on the panels are squeezed and then released to fit within a retaining channel  146  formed in bottom flange retaining rod  129 . Panels  122  and  123  have their interior surfaces positioned over panel backing retaining rods  130  and  131  when the flanges are positioned in channels  143  and  146  to assist in maintaining the cylindrical shape of the panels.  
         [0026]     Panels  122  and  123  are preferably formed from a thin resilient sheet material, such as thin sheet metal, that can be shaped into a pliable, semi-cylindrical configuration, and folded along its long edges to form top flanges  140 ,  141  and bottom flanges  144 , 145 .  
         [0027]     Still referring to  FIGS. 1 and 2 , a light source, preferably in the form of bulbs  161  and  162  retained in sockets  162  and  163 , is mounted to a light source rod  150  which is inserted through frame end bracket  151  of frame  20  along rotation axis  8  of cylinder  4  to position the light source within the interior of the cylinder. Bulb sockets  162 ,  163  are attached to rod  150  by brackets  164  and  165 , respectively. Rod  150  is fixedly secured to frame  20  at end bracket  151  by collar  152 . Quiet and smooth rotation of cylinder  4  by motor  121  about axis  8  is achieved using a rotator bushing  153  that rotatably supports end plate  127  of the cylinder. As shown in  FIG. 2 , wires  155  to supply electrical power to bulbs  161  and  162  enter the interior  6  of cylinder  4  through aligned openings in end plate  127 , bushing  153 , end bracket  151  and collar  152 . It will be appreciated by a person skilled in the art that other arrangements to position a light source within the interior  6  of cylinder  4  are possible.  
         [0028]     The above described panel mounting arrangement and the light source mounting scheme permit ready access to the bulbs within interior  6  of cylinder  4  to permit changing of bulbs in the event of a bulb failure.  
         [0029]     Panels  122  and  123  forming the sidewall of cylinder  6  are formed with apertures  91  therethrough. Rotation of cylinder  4  by motor  121  causes the apertures to rotate about cylinder axis  8 . Light from light bulbs  161  and  162 , which are stationary within interior  6  of the cylinder, is transmitted through the moving apertures for display on a screen in order to create a simulation of moving and flickering flames.  
         [0030]     It has been discovered the imitation flame display is enhanced if the interior surface of panels  122  and  123  are non-reflective or light absorbing. For example, in a preferred arrangement, the interior surfaces of panels  122  and  123  facing the interior  6  of cylinder  4  may be formed with a matte black surface. Such a surface can be created by applying a matte black paint to the interior panel surfaces. It will be apparent to one of skill in the art that other non-reflective or light absorbing surfaces may be used by forming the panels of non-reflective material or by applying other non-reflective coating to the interior surfaces of the panels. For example, the application of any dull, flat finish by painting or otherwise to the interior surface of the drum will create the necessary non-reflective surface as opposed to the use or application of a surface having a smooth, glossy finish with a shine or luster. It is also possible for the exterior panel surfaces to be non-reflective or light absorbing.  
         [0031]     As best shown in  FIG. 3 , the apertures in panels  122  and  123  are preferably formed as curved, generally S-shaped perforations  91  or circular perforations  97  through the panels. The apertures are preferably stamped or molded in a pattern or array suitable for generating a flame display when projected onto a screen. In the illustrated embodiment of  FIG. 3 , generally flattened S-shaped perforations  91  are arranged in rows  93 ,  94  and  95  with the perforations in each row being offset or staggered from the perforations in an adjacent row. Circular perforations  97  are also formed in offset rows. Other aperture shapes and arrays of apertures are possible. The staggering of the perforations  91  tends to create a waved flickering effect as the cylinder rotates that better simulates real flames in the flame display.  
         [0032]     The central zone  100  of each panel can be formed with more apertures than the end zones  101  of the panel to create a brighter central region with more imitation flames in the flame display. Alternatively, having brighter bulbs or a greater concentration of bulbs positioned in the central region of interior  6  of cylinder  4 , or a combination of both such arrangements will achieve the same effect of a brighter central region in the imitation flame display.  
         [0033]     Referring to  FIG. 4 , the apparatus  2  for projecting light of the present invention is shown installed in an electric fireplace  10  designed to display imitation flames on a screen  24 .  FIG. 4  is a cross-sectional elevation view through the electric fireplace unit. Hollow cylinder  4  is mounted at the rear of an enclosure  21  behind a simulated fuel source  22  at the front of the enclosure, which is positioned in front of screen  24 . Simulated fuel source  22  comprises an artificial log or charcoal arrangement. Screen  24  comprises a translucent panel having a rear facing side  26  onto which moving flames are back-projected from apparatus  2  for viewing from a front facing side  25 . Simulated fuel source  22  and the front facing side  25  of screen  24  are viewable through a front window  30  of the fireplace enclosure  21 .  
         [0034]     The front facing side  25  of screen  24  preferably has reflective properties such that a reflection of the simulated fuel source  22  may be seen on the front facing side  25  of screen  24 . A portion of the front facing side  25  may optionally feature a “brick” pattern of alternating substantially non-reflective portions and substantially reflective portions.  
         [0035]     The rear facing side  26  is optionally coated or provided with a frosted coating or sheet (not shown) that causes the light to diffuse as it passes through screen  24 . Such a diffusion coating or sheet softens or blurs the edges of the imitation flames in the flare display.  
         [0036]     Also mounted within fireplace enclosure  21  directly behind screen  24  is a flame effect mask  32 .  FIG. 5  provides a front view of the mask which is an opaque surface having a lower edge formed with generally triangular cut outs  34 . Mask  32  acts to block some of the light emitted by cylinder  4  to create a more realistic imitation flame display on screen  24 .  
         [0037]     The arrangement of cylinder  4 , flame effect mask  32  and screen  24  is such that light  38  transmitted through the rotating apertures  91  of the hollow cylinder  4  and past the flame effect mask  32  is projected onto rear facing side  26  of screen for display on a front facing side  25  as simulated moving flames above artificial fuel source  22 .  
         [0038]     Screen  24  comprises a light diffusing panel that can be made of molded plastic that is translucent but not transparent, in order to soften and diffuse the light that is projected through the perforations of cylinder  4  producing a variable glow that enhances the simulation of flames while at the same time preventing viewing of cylinder  4  through the panel.  
         [0039]     The electric fireplace of the present invention as shown in  FIG. 4  can also incorporate a heater unit  40  comprising a conventional electrical heater  44  with heater coils  46  and a blower fan  51  for directing air past the coils. A second light source  48  can be positioned below artificial fuel source  22  to provide a glow of burning embers below the artificial logs or coals of the artificial fuel source.  
         [0040]     The fireplace is fitted with other standard components such as an on-off switch, a thermostat, and an overheat control circuit which allow the fireplace to be assembled into a unit that is functional, heat-producing, controllable, and safe.  
         [0041]     Although the present invention has been described in some detail by way of example for purposes of clarity and understanding, it will be apparent that certain changes and modifications may be practised within the scope of the appended claims.