Abstract:
A decorative, imitation candle includes a simulated wick which generates the appearance of an open flame in a darkened environment. A light pipe is located at the expected location of the wick. The exposed end of the light pipe has a tip which produces a point like a light source with a glare effect to darkness accommodated eyes when the device is illuminated. The glare is interpreted as an open flame without the need for a flame shaped terminating structure which is visible when the imitation candle is unlit.

Description:
BACKGROUND OF THE INVENTION 
   1. Technical Field 
   The invention relates to decorative, imitation candles and, more particularly, to an imitation candle simulating a lighted wick. 
   2. Description of the Problem 
   Numerous manufacturers have attempted to meet a demand for a flameless, candle like luminary using electrical illumination. There are many imitation candles available that use incandescent lamps or LED&#39;s as a light source. These devices address people&#39;s concern with having an open flame indoors. Most of these devices try to implement the appearance of a realistic flame using a specially shaped bulb or lens that is exposed to view. Typically, the bulb or lens sits on top of a thin cylindrical sleeve, which is shaped and colored to resemble a candle. The results are typically disappointing, especially when these devices are not illuminated. The visible, flame shaped artificial light source makes the imitation candle as a whole appear artificial. The result can look more like a caricature of a candle than a real candle. The color of incandescent light can leave something to be desired in many candles as well. 
   U.S. Pat. No. 6,616,308 teaches an imitation candle configured to diminish any expectation on the part of an observer of seeing an open flame. U.S. Pat. No. 6,616,308 is incorporated herein by reference. Visually, the key visual element of a real flame is a rather intense spot of light, which when viewed directly, could be bright enough in a dark environment to be a source of glare. In a dark environment, for example, when the human eye is adjusted for scotopic vision, the eye cannot tolerate the large contrasts in brightness and as a result the physical outline of the flame is often lost to the eye. In the case of artificial flame structures, often the outer surface is frosted, or the body has some pigmentation so that the flame structure is itself lit up. By spreading the light from the internal light source across a larger surface area, the intensity of light at the surface is much less than the driving source. Because of this lack of point source intensity, the brain does not interpret the flame structure as a real flame. Incandescent lamps that have clear glass flame structures reveal an intense filament, but the filaments are linear, so these only appear as point sources when viewed from some distance. 
   One approach to creating a realistic illusion of a flame is disclosed in U.S. patent application Ser. No. 10/844,075, filed 12 May 2004, which is incorporated herein by reference. This application discloses an LED hidden within a fixture above an imitation candle body. Light emitted by the LED is directed to illuminate the candle body and wick from above. The LED is driven by a variable current to produce flickering light. The imitation wick has a reflective tip which reflects the incident light to create a small bright spot. The bright spot at the tip of the wick is sufficiently bright that even though the light source may be flickering, the intensity remains strong enough that the eye cannot see the change in intensity of the spot. At the same time, light shines past the wick and onto the candle body where it is diffused throughout a relatively large volume. The light intensities within the candle body are much lower resulting in a dramatic, flickering effect. 
   For standalone imitation candles that are not housed in a permanent fixture, the approach of the &#39;075 application is more difficult to effect since there is no convenient place to hide the LED but within the candle body itself. If the effect of a lighted wick is to be reproduced it would be advantageous to produce a similar effect with a light source internal to the imitation candle. 
   Imitation candles that use incandescent lamps located at the tip of the candle do not produce a bright spot with the same effect as desired, at least at close distances, because the coil used in the bulb is not a true point source. The coil instead appears as a horizontal line source. Decorative applications of fiber optics have used fiber optic rods to transmit light from a central light source to a variety of emission points. Because the lighted fiber ends are small, they create a lighting effect that looks like lighted ‘hairs’, which cannot be produced by traditional light sources. 
   Another use of fiber optics has been as panel indicator light pipes. These have been designed and used in many forms to transmit light. No attempt, known to the present inventors, has been made to simulate illumination of an imitation wick. These have as their design objective to transmit as much light as possible from the light source into the light pipe. 
   SUMMARY OF THE INVENTION 
   According to the invention there is provided an imitation candle having a translucent body with an upper surface. A light source is located within the translucent body under the upper surface for illuminating the upper portion of the translucent body. A light pipe pierces the upper surface near its center. The light pipe has a buried portion beneath the upper surface and an exposed portion above the upper surface. The exposed portion terminates in a light diffusing tip end and the buried portion terminates sufficiently proximate to the light source to capture an effective quanta of light emitting from the light source for illuminating the light diffusing tip end at a desired intensity. Most of the rest of the exposed portion of the light pipe is modified to appear to be a burnt wick. 
   Additional effects, features and advantages will be apparent in the written description that follows. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
       FIG. 1  is a perspective view of an imitation candle. 
       FIG. 2  is a cross sectional view of a possible internal configuration for the imitation candle of  FIG. 1 . 
       FIG. 3  is a cross sectional view of an alternative internal configuration in accordance with a second embodiment of the imitation candle of  FIG. 1 . 
       FIG. 4  is a cross sectional view of still another embodiment of the invention. 
       FIG. 5  is a cross section of an imitation candle in accordance with the invention having enhanced light coupling from an LED light source to a fiber optic imitation wick. 
       FIGS. 6A-C  are variations on configurations of the imitation wick. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIG. 1  an exterior configuration for several possible embodiments of the invention is illustrated in perspective view. Imitation candle body  10  is a squat element, configured to resemble a self supporting candle which has burned down by the center. Imitation candle body  10 , which can be fabricated in wax or translucent plastic, contains an internal light source positioned within the imitation candle body so as to illuminate the candle body with a diffuse, flickering glow that simulates the appearance of a lit candle. A light pipe  12  extends upwardly from a central depressed section  14  in the upper surface  19  of imitation candle body  10 . As described below, a buried end of a light pipe  12  is positioned in sufficiently close proximity to the internal light source to capture a portion of the light emitted by the light source sufficient to generate a bright point source of light at an exposed tip end  18  at the opposite end of the light pipe. This opposite, exposed end of the light pipe  12  extends from candle body  10  at a location where a candle wick would normally be positioned. The extreme tip end  18  of light pipe  12  is roughened or faceted to diffuse the captured light and create the visible bright point source of light. A dark colored sleeve  16  extends from tip end  18  at least to the depressed surface  14  and covers the all but the tip end  18  of the exposed portion of light pipe  12  to simulate the look of a real, previously burned wick. Emission of light from the internal light source is indicated at letter “A” by phantom lines. 
     FIG. 2  shows a cross-sectional view of the imitation candle body  10  shown in  FIG. 1  illustrating a possible internal configuration thereof. A cavity  24  within the lower portion of imitation candle body  10  allows space for the installation of an electronics module (not shown) that provides the power source, switch and circuitry needed to drive the internal light source  20 . Internal light source  20  is preferably a super bright light emitting diode (LED) as described in U.S. Pat. No. 6,616,308 but could be an incandescent source. In addition to supplying current to the light source  20 , such an electronics module may include on/off timers, daylight sensors and a flicker energization circuit to cause the light source  20  to flicker after the fashion on an unstable candle flame. Light pipe  12  is disposed with one end located near to and open with respect to light source  20 . When light source  20  is illuminated light pipe  12  captures a small portion of the light emitted thereby. Light pipe  12  is preferably constructed using a single fiber optic cable with a diameter similar to a candle wick. Alternatively light pipe  12  could be a small bundle of smaller fiber optic filaments. The light captured by light pipe  12  from light source  20  is directed to the opposite end of the light pipe where it strikes a light diffusing tip  18 . Light diffusing tip  18  may be created by roughening or faceting the end of the light pipe so that it scatters light in all directions creating a point source of bright light. Still other alternate schemes may also be used to diffuse the light when it reaches the exposed end of the light pipe  12 . Dark colored, opaque sleeve  16  surrounds the expose portion of light pipe  12  excluding the light diffusing tip end  18  and serves to disguise the light pipe  12  and give it the appearance of a real wick which has burned down. Alternatives to the sleeve  16  could be used to disguise the light pipe  12  as a wick, but care must be taken not to interfere with the light transmitting properties of the light pipe  12 . An opaque barrier  22  is disposed over cavity  24  and under light source  20 . Opaque barrier  22  controls illumination levels from top to bottom of the imitation candle body  10 , limiting light emission to the upper portion of the body. 
     FIG. 3  shows an alternative embodiment for the internal configuration of imitation candle body  10 . An array of LED&#39;s  21  are disposed around light source (LED)  20  within imitation candle body  10 . The primary role of the additional LED&#39;s  21  is to more fully illuminate imitation candle body  10  thus allowing more of the light from main light source  20  to be captured by the light pipe  12  increasing the intensity of light emitted at the light diffusing tip end  18 . 
     FIG. 4  shows an embodiment of the invention in a taper style candle body  100 . Taper style candle body  100  has a small channel  26  running nearly the length of the body from near its top out through the bottom of the body is used to allow connection of the light source  28  to an external circuit  30 . External circuit  30  would typically be hidden in a candle pedestal. Alternatively the electronics could be miniaturized to fit in the imitation candle body at some expense. The upper end of taper style candle body  100  is closed and forms a depressed surface  32  with a fiber optic light pipe  34  passing through the depressed surface from a lower end adjacent light source  28  to an exposed tip end  38 . Again, most of the exposed portion of light pipe  34  is enclosed in a darkened, opaque sleeve  36 , except for the light diffusing tip end  38 . 
     FIG. 5  shows an alternative embodiment of the invention wherein the light pipe  40  is designed to capture a large portion of the light emanating from the light source  20 . The end of light pipe  40  adjacent light source is bulbous, and extends around the light source forming a cylindrical receptacle  44  in which LED  20  is disposed. An external LED  42 , located above the imitation candle body  10  and typically hidden within a fixture that contains the candle, is used to illuminate the imitation candle body from above. 
     FIGS. 6A-C  shows detailed views of three possible implementations of the light source  20  and various light pipes.  FIG. 6A  shows a simple light pipe  12  one end of which has been scratched and roughened to form a light diffusing tip  18 . A portion of the light emanating from the light source  20  is captured by the light pipe  12  and directed to the light diffusing tip  18  where it is scattered to form a bright point source of light.  FIG. 6B  shows a light pipe  50  which has been molded as an integral part of the epoxy body  27  that encapsulates the LED  20 .  FIG. 6C  shows an alternate construction that using a light pipe  60  that is polished on both ends and uses a separate diffuser  70  to redirect the light coming from the exposed end  80  of the light pipe  60 . In all three light pipes  12 ,  50  and  60  light is illustrated as being transmitted through the pipes, being reflected inwardly by the surface of the pipe until encountering an irregular, light diffusing, terminating end. The letter D illustrates scattering of the light. The light pipe is disposed to capture sufficient light from the light source to create a glare effect to darkness accommodated eyes from the light diffusing tip  18 . 
   The invention provides an imitation candle giving a realistic illusion of supporting an exposed flame while retaining flickering, illuminated body. 
   While the invention is shown in only one of its forms, it is not thus limited but is susceptible to various changes and modifications without departing from the spirit and scope of the invention.