Patent Publication Number: US-7210256-B2

Title: Artificial fireplace

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This is a continuation-in-part application of application Ser. No. 10/982,287, filed Nov. 5, 2004. 

   FIELD OF THE INVENTION 
   This invention generally relates to artificial fireplaces. 
   BACKGROUND OF THE INVENTION 
   Fireplaces are common household devices that are used to provide heat and a pleasing aesthetic. However, traditional fireplaces are expensive, create smoke, and are a fire hazard so artificial fireplaces or stoves are popular alternatives. Artificial fireplaces are less expensive than traditional fireplaces and they do not use actual flames, so there is no smoke or fire hazard. 
   Typically, an artificial fireplace is formed from a ceramic housing with a viewing aperture and a hollow interior. The ceramic housing contains a light source, a viewing screen, a flame simulation device, and a simulated fuel source. The light source is disposed on the bottom of the interior of the housing, underneath the flame simulation device and between the viewing screen and the rear of the housing. The light emitted by the light source bounces off of the flame simulation device and projects the image of the flame simulation device onto the viewing screen. The simulated fuel source, which is typically shaped as one or more wooden logs, is disposed adjacent to the viewing screen and positioned such that it appears the flames projected on the screen are emanating from the logs. The simulated fuel source additionally serves to conceal the operation of the light source and flame simulation device. 
   The prior art artificial fireplace is shown in  FIGS. 1 and 2 .  FIG. 1  is a side elevational view of an artificial fireplace, shown in section to better illustrate the placement and function of the various components. The housing  20  of the artificial fireplace  22  defines a hollow cavity  24  which contains a light source  26 , a flame simulation assembly  28  generally above the light source  26 , a simulated fuel source  32  located so as to conceal the light source  26  and the flame simulation assembly  28  from the field of vision  34  through the viewing aperture  36 , and a viewing screen  38  located between the light source  26  and the simulated fuel source  32 . The light source  26  and the flame simulation assembly  28  are operatively coupled to suitable power sources, which are not shown. The light source  26  emits light  40  that strikes some of the flame elements  42  affixed to the flame simulation assembly  28 . The light  40  reflects off of the flame elements  42  and an image of the flame elements  42  is projected onto the viewing screen  38  at a point generally above the simulated fuel source  32 . The end result is the appearance that there are flames emanating from the simulated fuel source  32 . The flame simulation assembly  28  rotates, which causes the light  40  to strike the flame elements  42  at different angles as they move. The result is the appearance of motion within the image that is projected onto the viewing screen  38 . Typically, the viewing screen  38  is made of glass or plastic and comprises a transparent surface which faces the viewing aperture  36  and a diffusing surface which faces the rear of the housing  20 . In some prior art artificial fireplaces  22 , there is also a fuel light source  44  located within the simulated fuel source  32  which projects light  40  through small apertures  46  in the simulated fuel source  32  for creating the appearance of smoldering embers. Additionally, some prior art artificial fireplaces  22  also include a dimmer assembly which can be used to selectively adjust the brightness of the flame image and/or the brightness of the simulated embers. 
     FIG. 2  is a front perspective view of the prior art light source  26  and flame simulation assembly  28 . As illustrated in  FIG. 2 , the prior art light source  26  is typically one or more light bulbs  48 . The flame simulation assembly  28  essentially comprises a shaft  50  that is journaled in a bearing  52  in one leg  54  of a U-shaped frame  56 . The other end of the shaft  50  extends through a hole  58  in the other leg  60  of the frame  56  and is operatively coupled to a motor  62  which causes the shaft  50  to rotate about its axis. Also typically provided, but not shown, is a control assembly for selectively adjusting the speed at which the shaft  50  rotates. Affixed to the shaft  50  are several irregularly-shaped flame elements  42  which are made of a material suitable for reflecting the light  40  emitted by the light source  26 . As a result of the flame elements  42  rotating as the light  40  strikes them, the flame image projected onto the viewing screen  38  appears to flicker and move. 
   Heretofore, the biggest problem with artificial fireplaces is that they do not produce a realistic flame image. One known method of producing a more randomly-moving, and therefore more realistic, flame image is to use a rotating shaft with attached flame elements to simulate flickering flames, as can be seen in U.S. Pat. No. 2,984,032. The light from the light source strikes the irregularly-shaped flame elements at different angles as they rotate, which results in a flame image that appears to leap and change shape. While this creates the image of a flickering flame, the image is not realistic because the result is an orange glow. A flame contains a variety of colors; primarily orange and red, but there are also instances of blue and green in places. The usual light source in an artificial fireplace is a monochromatic light bulb, which results in an unrealistic orange glow. Some prior art fireplaces attempt to create a multi-colored flame by using rotating flame elements of different colors, but this does not produce a realistic flame image. Alternatively, some prior art fireplaces use stationary flame elements and instead produce the illusion of flickering flames with a light source which flickers or blinks in a predetermined pattern or at random intervals. This results in an unsatisfactory flame effect and disadvantageously shortens the lifespan of the light source by repeatedly cycling it on and off. 
   In addition, there are other problems associated with using one or more light bulbs as a light source. First, light bulbs have a relatively short life span and they must be replaced frequently. This life span is further shortened when the light source is designed to flicker or blink randomly or in a pre-selected pattern. Furthermore, light bulbs produce a fair amount of heat and, depending on the material used to form the components disposed within the fireplace, this can create a fire hazard. Finally, light bulbs consume more electricity than do other light-producing devices. Therefore, there is a need for an artificial fireplace with a light source that produces a realistic multi-colored flame image and lasts longer, operates more efficiently, and generates less undesirable heat than traditional light sources. 
   It is accordingly a general aspect or object of the present invention to provide an artificial fireplace which produces a more realistic flame image. 
   Another aspect or object of this invention is to provide an artificial fireplace with a light source which has a superior life span compared to prior art light sources. 
   Another aspect or object of the present invention is to provide an artificial fireplace with an improved light source that produces less undesirable heat within the interior cavity of the fireplace than prior art light sources. 
   Another aspect or object of the present invention is to provide an artificial fireplace with an improved light source that consumes less electricity than prior art light sources. 
   Other aspects, objects and advantages of the present invention will be understood from the following description according to the preferred embodiments of the present invention, specifically including stated and unstated combinations of the various features which are described herein, relevant information concerning which is shown in the accompanying drawings. 
   SUMMARY OF INVENTION 
   The present invention relates to an artificial fireplace which operates similarly to prior art fireplaces, but utilizes a solid state light source, which differs from traditional incandescent light sources by deriving light from a solid object rather than from a vacuum tube. Preferably, a plurality of light emitting diodes (LEDs) removably mounted to a printed circuit board (PCB) serve as a solid state light source to produce a more realistic flame image. Each LED, when operative, emits light having a generally constant brightness (as opposed to a flickering or blinking light). This generally constant level of brightness may be manually adjusted with an optional dimmer assembly. 
   The preferred embodiment of the invention is an artificial fireplace with this improved light source located at the bottom of the hollow interior cavity of the fireplace. The light source is disposed generally beneath a horizontal shaft which carries a plurality of flame elements. The horizontal shaft is operatively coupled to and rotated by a motor, such that the light from the LEDs strikes some of the flame elements as they rotate into the path of the beams of light from the LEDs. Preferably, the flame elements are constructed of a light-reflecting material, such as aluminum, so the light reflects off of some of the elements and their image is transmitted to the viewing screen. In a preferred embodiment the viewing screen is made of a transparent material, such as glass or plastic, and comprises a transparent surface facing the viewing aperture and a diffusing surface which faces the rear of the housing and can be made of plastic foil. A simulated fuel source, which takes the form of a plurality of wooden logs in the preferred embodiment, conceals the operation of the light source and flame elements. Additionally, the simulated fuel source may be generally hollow for housing a second set of LEDs which simulate glowing embers. Preferably, the majority of the LEDs used to simulate the flames are red or orange, but some may be green or blue in order to produce the realistic image of a flickering orange and red flame with instances of green and blue. Besides creating a more realistic flame image, LEDs can be used approximately ten times longer than incandescent light bulbs before replacement, they produce less undesirable heat inside of the fireplace, and they consume approximately 15–20% of the electricity of an incandescent light bulb. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the course of this description, reference will be made to the accompanying drawings, wherein: 
       FIG. 1  is a side elevational view, in section, of the components and operation of a prior art artificial fireplace; 
       FIG. 2  is a front perspective view of the light source and flame simulation assembly of the artificial fireplace shown in  FIG. 1 ; 
       FIG. 3  is a front perspective view of the light source and flame simulation assembly of the preferred embodiment; 
       FIG. 4  is a front perspective view of the light source and flame simulation assembly of a second embodiment; 
       FIG. 5  is a top plan view of the light source shown in  FIG. 3 ; and 
       FIG. 6  is a functional block diagram of the light source shown in  FIG. 3  and an optional dimmer assembly. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriate manner. 
     FIG. 3  illustrates a preferred embodiment that is generally similar in operation to the structure shown in  FIGS. 1 and 2 . One important difference between the structure shown in  FIG. 3  and the one shown in  FIGS. 1 and 2  is the addition of an improved light source  64 . The light bulb  48  of the prior art light source  26  is replaced by a plurality of light emitting diodes (LEDs)  66  which are removably affixed to a printed circuit board (PCB)  68 . The LEDs  66  and PCB  68  are operatively coupled to a suitable power source which is not pictured. A top plan view of a preferred arrangement of the LEDs  66  on the PCB  68  is illustrated in  FIG. 5 . The size of the PCB  68  and the number of LEDs  66  attached thereto may vary depending on the size of the housing  20 . As many LEDs  66  as will fit onto the PCB  68  may be used, but fifteen LEDs  66  are used in a preferred embodiment. The LEDs  66  may be colored so as to produce a more realistic flame image on the viewing screen  38 . In a preferred embodiment, eight of the LEDs  66  are orange, five are red, one is blue and one is green. Depending on the preference of the user, the orange LEDs  66  may be placed closest to the viewing screen  38  for a more orange flame image, but any color arrangement is within the scope of this invention. The individual LEDs  66  may be removed and replaced with LEDs  66  of a different color if the user wants to change the color of the image that is ultimately projected onto the viewing screen  38 . Furthermore, the LEDs  66  need not be functionally identical to one another and it is possible to use LEDs  66  of different electrical characteristics without departing from the scope of this invention. 
   In a preferred embodiment, the rotating flame elements  42  are made of reflective aluminum, which reflects the colored light  40  from the LEDs  66  onto the viewing screen  38 . The result of using LEDs  66  instead of a light bulb  48  is a more realistic, randomly-flickering flame image that is primarily reddish-orange with instances of green and blue. Additional advantages are an improved life span, less undesirable heat emitted within the artificial fireplace  22 , and lower electricity consumption. 
     FIG. 4  illustrates an alternate embodiment of the improved light source  64  and a flame simulation assembly  28  with slit-type flame elements  70 . The light source  64  in  FIG. 4  operates identically to the light source  64  shown in  FIG. 3 , but the PCB  68  is located within a generally hollow cylinder  72  which is affixed to the shaft  50 . The cylinder  72  has a number of slit-type flame elements  70  through which the light  40  emitted by the light source  64  passes. The slit-type flame elements  70  are shaped such that the light  40  passing through the cylinder  72  projects a flame-shaped image onto the viewing screen  38 . The cylinder  72  rotates while the light source  64  preferably remains stationary, so the image of the light  40  passing through the slit-type flame elements  70  appears to move on the viewing screen  38 . 
     FIG. 6  illustrates a block diagram of an optional dimmer assembly  74  that can be used to allow selective adjustment of the brightness of the light  40  emanating from the light source  64 . While the brightness of the light  40  may be selectively adjusted, each LED  66  otherwise produces a non-blinking light  40  having a generally constant brightness. The LEDs  66  and PCB  68  are operatively coupled to a potentiometer  76  which is electrically coupled to an assembly of diodes and capacitors  78  which, in turn, is electrically coupled to a transformer  80 . The transformer  80  is electrically coupled to a suitable power source  82 , which is typically a household electrical outlet. LEDs  66  must operate on a low voltage, otherwise they may be destroyed, so the transformer  80  steps down the voltage from the power source  82  before it is delivered to the LEDs  66 . Additionally, LEDs  66  use direct current, so the assembly of diodes and capacitors  78  converts the alternating current delivered by the power source into usable direct current. The voltage delivered to the LEDs  66  through the PCB  68  can be varied by adjusting the potentiometer  76  with a suitable control assembly, which is not pictured. As the voltage delivered to the LEDs  66  through the PCB  68  varies, the intensity of the light  40  emitted by the LEDs  66  also varies which consequently affects the brightness of the image that is projected onto the viewing screen  38 . The LEDs  66  may have different electrical properties, so decreasing the voltage may cause some LEDs  66  to become deactivated, while others remain lit. Similarly, for a given voltage level, different LEDs  66  may produce light  40  having a different brightness without departing from the scope of the present invention. Also shown is a fuel light source  44  that may be added to the artificial fireplace  22  in order to create the appearance of smoldering embers within the simulated fuel source  32 , as described in  FIG. 1 . Preferably, all of the LEDs  66  of the fuel light source  44  are red. The dimmer assembly  74  may be coupled to either the light source  64  or the fuel light source  44 , or it may be coupled to both of them. Additionally, there may be separate dimmer assemblies  74  coupled to the light source  64  and the fuel light source  44 , so the brightness of the light which each emits can be independently adjusted. 
   It will be understood that the embodiments of the present invention which have been described are illustrative of some of the applications of the principles of the present invention. Numerous modifications may be made by those skilled in the art without departing from the true spirit and scope of the invention, including those combinations of features that are individually disclosed or claimed herein.