Patent Abstract:
A large plurality of artificial, battery-operated, electronic candles are arranged to be simultaneously recharged upon placement on a series of interconnected charging trays that include a transformer primary winding at defined locations thereon. The primary windings are driven by an AC signal whose duty cycle is controlled by a pulse width modulator IC to induce a voltage across secondary windings contained within the candle housing. This induced signal is rectified to produce the battery charging current and the delivery of the charging current to the rechargeable batteries is controlled by a microprocessor IC.

Full Description:
BACKGROUND OF THE INVENTION 
     I. Field of the Invention 
     This invention relates generally to electronic candles used to simulate actual wax candles, and more particularly to a system for recharging a large plurality of such candles. 
     II. Discussion of the Prior Art 
     There are artificial candles on the market presently that replicate the look of a burning wax candle, but which incorporate a yellow LED and a suitable electronic controller for imparting a flickering illumination of the LED to simulate the glow of a burning wax candle. However, for the most part, those candles embody a rechargeable battery and a circuit that had to be plugged into a DC current source to effect recharging of the candle, one at a time. 
     Many restaurants often include a so-called votive candle on each table in the restaurant to add to the ambience of the place. A votive candle is generally 2.0 inches in height by 1.5 inches in diameter and is contained in a suitable holder, such as a glass cup. If one wished to substitute an electronic artificial candle for the real thing, a way would have to be devised to simultaneously recharge a large plurality of such artificial candles so that when fully charged, they may be distributed throughout the restaurant and turned on upon arrival of a patron at a given table. 
     The prior art, as represented by U.S. Pat. No. 6,819,080 to Barbeau et al, teaches a stand-alone recharging platter capable of charging a set number of artificial candles. Such stand-alone platters have a power cord for supply an electrical charge. If a restaurant needs to charge more candles than the platter is adapted to handle, the restaurant must plug multiple platters into multiple wall sockets. 
     Another concern on the part of a restaurant owner is the potential loss of such a candle through theft. The artificial candles, being both attractive and of more than negligible cost, loss through theft can be a problem. 
     A need therefore exists for a decorative artificial candle design that can be used in a restaurant environment as a table decoration and that is adapted to be recharged simultaneously with many other identical candles in unison rather than individually. 
     A need further exists for an artificial candle design that incorporates features that discourage theft. 
     A further need is an artificial candle that is more realistic in its operation than existing prior art artificial electronic candles currently available. Specifically, a need exists for an artificial candle that more accurately simulates a real wax candle in that it can be extinguished by a puff of air blown at it at close range. 
     SUMMARY OF THE INVENTION 
     The present invention provides a charging stand or tray that can be concatenated with a plurality of identical trays where each tray is capable of supporting a plurality of individual artificial electronic candles as they are simultaneously having their internal batteries recharged. Each of the individual candles may incorporate a position sensitive module capable of detecting whether a candle is otherwise than in an upright position and to provide an audible signal unless the candle is returned to its upright position within a prescribed time interval. 
     In accordance with a further feature of the invention, a suitable transducer can be incorporated into the individual candles where the transducer is capable of detecting pressure and temperature changes occasioned by a person blowing his/her breath onto the candle and causing the LED light source used to simulate the flame to be extinguished. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The foregoing features, objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of a preferred embodiment especially when considered in conjunction with the accompanying drawings in which like numerals in the several views refer to corresponding parts: 
         FIG. 1A  is a pictorial view showing four charging trays joined together and populated with a plurality of artificial candles; 
         FIG. 1B  is an enlarged view of four charging trays connected together and showing the plug and socket detail; 
         FIG. 2  is a side elevation view of the artificial candle with the decorative outer shroud removed; 
         FIG. 3  is a cross-sectional view taken through the artificial candle incorporating an anti-theft feature; 
         FIG. 4  is a view of a charging tray populated with artificial candles and cross-sectioned to show the engagement between a transformer primary winding forming part of the charging tray and a secondary winding disposed in the artificial candle; 
         FIG. 5  is an electrical schematic diagram of the artificial candle incorporating the anti-theft feature; 
         FIG. 6  is a schematic electrical diagram of the artificial candle incorporating the blow-out feature; and 
         FIG. 7  is an electrical schematic diagram of an inner connected pair of charging trays and a current limiter circuit used therewith. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to  FIG. 1A , there is shown a plurality of electrically and mechanically interconnected artificial candle charging trays  2 ,  4 ,  6 ,  8  that are populated with a plurality of battery-operated artificial candles  10 . Without limitation, each charging tray may hold up to a dozen artificial candles in which a rechargeable DC battery is connected through a semiconductor switch to a yellow LED and where the switch is, in turn, controlled by a programmed microprocessor chip such that the LED may be made to flicker much like the light given off by a real wax candle. Just how this is achieved will be explained in greater detail herein below. 
     With continued reference to  FIG. 1A , power for the charging tray is derived from a conventional AC/DC adapter that when plugged into a wall socket at 110 volts produces a 12 volt DC output. Connected in the cable leading from the adapter  12  to the first recharging tray  2  is a current limiter circuit  14 . 
       FIG. 1B  illustrates the manner in which plural trays,  2 ,  4 ,  6  and  8 , can be concatenated so that each is supplied with power from the AC to DC adapter, via the current limiter circuit  14 . The DC input from the current limiter  14  enters through a plug  15  that projects laterally from a side edge  17  of the tray  2 . Formed inwardly in the opposed side surface  19  of the tray  2  is a female socket dimensioned to accommodate the insertion of a male plug  21  that projects from the side surface of an identical tray  4 . Likewise, tray  6  has a plug  23  mating with a socket in the side surface of the tray  4 , etc. Contained within the hollow interior of the trays  2 ,  4 ,  6  and  8  are printed circuit boards and wiring that operatively connect the contacts of the plug  15  to corresponding terminals in the socket into which the plug  21  of the tray  4  is inserted. The manner of inner connection is shown in the electrical schematic diagram of  FIG. 7 . 
     Referring next to  FIGS. 2 and 3 , each of the battery operated artificial candles comprises a yellow LED  16  that simulates the candle flame. It is surrounded by a translucent bulb  18  ( FIG. 3 ) having the tapered shape of a flame and used to defuse the light emanating there through. The LED  16  projects out through an aperture in the top surface  20  of the molded plastic candle housing  22  or shroud, which is generally a hollow right-circular cylinder that contains the electronic circuitry for powering the LED  16 . 
     With continued reference to  FIGS. 2 and 3 , a rechargeable battery  24  is positioned directly below a socket  26  for the LED  16  and adjacent the underside of a printed circuit board assembly  28  on which much of the circuitry of  FIG. 7  is disposed. A pushbutton “on/off” switch  30  is disposed within the housing  22  and is accessible through an aperture formed in the base  32  of the candle. The base also includes a bore  34  and surrounding the bore  34  is an electrical coil  36  or windings which, as will be further explained, acts as the secondary winding of a transformer whose primary winding is disposed about a ferrite core in a hollow post on the charging tray that is adapted to fit within the bore  34  of the artificial candle. The arrangement is more clearly shown in the cross-sectioned view, of  FIG. 4 . 
     As shown in  FIG. 4 , the recharging trays for the artificial candles include a hollow, box-like base  38  formed of injection molded plastic. Disposed within the interior of the base  38  is a printed circuit board  40  that contains the circuitry of one of the two recharging trays illustrated in the electrical schematic diagram of  FIG. 7 . 
     Formed into the top surface of the base  38  is a plurality of indented circular sockets dimensioned to receive a bottom portion of an artificial candle in each. Centrally located in each of the sockets and projecting vertically from the center thereof are cylindrical posts  42 . Contained within each such post is a magnetic core  43  encircled by coil windings, as at  44 , and which form the primary winding of a transformer that is inductively coupled to the coil  36  that surround the bore  34  in the candle when the candles are resident in the sockets of the base  38 . 
     Referring back to  FIG. 2 , also contained within the cylindrical housing  22  of the artificial candle is a motion sensor  46 . The motion sensor  46  includes three small tubes  48 ,  50  and  52  that contain a conductive ball in the lumens thereof, the balls being free to move between electrical contacts disposed at opposed ends of each of the tubes. Thus, for example, when the artificial candle is resting on a flat horizontal surface, the conductive balls will be at the lower end of each of the tubes  48 ,  50  and  52 , but when the candle is tipped from its upright position, gravity will cause the conductive balls to shift in position to close a different set of contacts, thus indicating that the candle is no longer upright. 
     Also visible in  FIG. 2  is a battery-operated buzzer  54  which will be made to sound whenever the artificial candle is not in its upright position for a predetermined length of time. Thus, for example, should a restaurant patron attempt to make off with a candle by placing it in a pocket or purse, the device will give off an audible sound to alert restaurant personnel that a candle is being taken. 
       FIG. 5  is an electrical schematic diagram of the circuitry contained within the housing  22  of the artificial candle incorporating the anti-theft feature. The transformer T has a center tapped winding where the center tap is connected by conductors  100  and  102  to circuit ground. The opposed outer ends of the secondary winding are connected through rectifier diodes D 201  and D 202  to a junction point VCC. A smoothing capacitor C 201  is connected between that junction and the center tap terminal of the transformer winding, T. 
     Connected between the junction VCC and ground is a series combination of an NPN transistor Q 4  and a resistor R 14 . Connected between the base electrode of Q 4  and ground is a reference Zenar diode ZD 1  and connected between the junction VCC and the base electrode of Q 4  is a resistor R 1 . 
     A PNP transistor Q 1  has its emitter electrode coupled to the junction VCC by a current limiting resistor R 2  and the collector electrode of Q 1  is connected through a diode D 1  to a junction point VDD. The base electrode of Q 1  is connected to ground through a series combination of a resistor R 4  and the emitter to collector path of a PNP transistor Q 2 . More particularly, the emitter electrode of Q 2  is connected directly to ground while its collector electrode connects to the base electrode of Q 1  via the resistor R 4 . 
     A pair of diodes D 4  and D 5  are connected in series between the junction VCC and the base electrode of transistor Q 1 , the purpose of which is to apply an appropriate bias for transistor Q 1 . 
     Control over the mode of operation of the candle is dictated by a programmed microprocessor U 1  which preferably comprises a Type FS260, an 8-bit microprocessor. A push-button off/on switch for the artificial candle, S 1 , is connected between ground and input pin B 1  of the microprocessor and a capacitor C 6  is connected directly in parallel with the switch S 1 . Connected between input terminals B 0  and B 2  are positioned sensing switches S 301  and S 302  and S 303 . These are the same devices as referred to by reference numerals  48 ,  50  and  52  in the drawing of  FIG. 2 . A debounce capacitor C 5  is connected in parallel with these three position sensitive switches. 
     An NPN transistor Q 5  has its emitter electrode tied to ground and its collector electrode connected to the input terminal B 3  of the microprocessor U 1 . The base electrode of Q 5  is connected through a biasing resistor R 3  to the junction point between the emitter electrode of Q 4  and the resistor R 14 . That junction is also connected by means of a conductor  103 , a diode D 2 , and a resistor R 17  to output terminal A 3  of the microprocessor U 1 . The common junction between the diode D 2  and the resistor R 17  is coupled by a resistor R 15  to the reset terminal RETB of the microprocessor and by a conductor  104  to the VDD terminal of the microprocessor U 1 . 
     A first LED, preferably green in color, has its anode electrode tied to the conductor  104  and its cathode electrode connected, via a resistor R 7 , to the output terminal B 4  of the microprocessor. Likewise, a second LED, preferably red in color, has its anode electrode connected to the conductor  104  and its cathode electrode connected by a resistor R 6  to output terminal B 5  of the microprocessor. 
     The output terminal B 6  of the microprocessor is connected through a series resistor R 11  to the base electrode of a PNP transistor Q 6  whose emitter electrode connects to the positive terminal of a rechargeable battery BT 1  and whose negative electrode is connected to ground. The rechargeable battery, for example, may be a 3.6 volt 330 ma lithium battery, but limitation to that type of rechargeable cell is not to be inferred. 
     The collector electrode of a transistor Q 6  connects to ground through a resistor R 12  and a yellow LED, labeled LED  1 , which is the flame LED  16  in  FIGS. 2 and 3  of the drawings. The positive battery terminal BT+ is also connected through a diode D 3  to the VDD terminal of the microprocessor thereby supplying its operating voltage. The cathode of the diode D 3  connects to conductor  104  and a capacitor C 3  connects between that conductor and ground. A resistor R 16  couples the VDD terminal of the microprocessor to its OSC 1  terminal. 
     With continued reference to  FIG. 5 , the anode electrode of the diode D 3  connects through a series resistor R 9  and a capacitor C 7  to ground. Connected directly in parallel with the capacitor C 7  is a further resistor R 10 . The common terminal between the resistor C 7 , the resistor R 9  and the resistor R 10  is tied to the input terminal A 1  of the microprocessor. 
     Programmable shunt regulator U 2  is connected between the microprocessor input terminal A 4  and ground and its reference electrode is connected by means of a capacitor C 4  to ground. The reference electrode is also directly connected to the device&#39;s cathode. 
     Completing the circuit of  FIG. 5  is an audible signaling device or buzzer B 1  having a first terminal thereof connected to the VDD terminal, i.e., the battery&#39;s positive terminal and the second terminal of the buzzer B 1  connects through an NPN transistor switch Q 3  to ground. The base electrode of Q 3  has a resistor R 8  connecting it to the terminal A 5  of the microprocessor U 1 . 
     In operation, and assuming that the battery potential BT+ is below a certain potential and it is appropriately mounted on the charging tray with the post  42  located in the bore  34 , transistor Q 1  will be forward biased and a DC current resulting from rectification of the induced voltage across the secondary winding of the transformer T becomes available to charge the battery. When the battery becomes charged to the point where its voltage BT+ is at a predetermined value, the microprocessor is programmed to output a signal on its terminal A 2  to reverse bias the transistor Q 2  which has the effect of shutting off the charging current flow through the transistor Q 1  to the battery. 
     With the battery fully charged and assuming the candles have been removed from the tray, depression on the on/off switch Si inputs a ground signal to terminal B 1  of U 2  which has the effect of driving the transistor Q 6  into conduction, whereby current flows to the candle lamp LED 1  causing it to glow. The candle flame LED 1  is made to flicker by the microprocessor suitably varying the on/off state of the transistor Q 6 . However, if the on/off switch Si is depressed a second time, the microprocessor is programmed to cause a steady current to flow through transistor Q 6 , such that LED 1  no longer flickers. A third depression of the on/off switch is effective to turn off the candle. 
     Assuming that the battery is fully charged, the candle has been removed from the base  38  and that the on/off switch has been depressed either once or twice in succession and then the candle set down on a flat, horizontal surface, such as on a patron&#39;s table, the LED 1  will continue to glow. However, if the patron should now pick up the candle from the table and, in doing so, tip it so that its top surface  20  is non-horizontal, one or more of the position sensitive switches S 301 , S 302  and S 303  will reverse state and input a signal between microprocessor terminals B 0  and B 2 . Upon detection of this condition for a programmed period, say 5 seconds, the microprocessor will issue a signal on output terminal AS to turn on the transistor Q 3  and complete a circuit from the battery through the buzzer to ground causing the buzzer to emit an audible signal that can attract attention of a restaurant employee. Turning on the buzzer B 1  also results in the LED 2  flashing on and off at one second intervals which is a further attention getter. This state will continue until the candle is returned to the charging tray that is located to be accessible only to restaurant employees. 
     Turning next to  FIG. 6 , it is substantially identical in its construction to that of  FIG. 5  except that the buzzer and position sensitive switches S 301 , S 302  and S 303  are eliminated and replaced with circuitry that adds further realism to the artificial candle. Specifically, if the flame LED is glowing in either its blink mode or its steady mode and a patron blows air at the flame, the flame will be extinguished. 
     As seen in  FIG. 6 , connected between the microprocessor input terminals B 0  and B 2  is the circuitry shown enclosed by the broken line box  105 . It includes a PVDF pyro/piezo film transducer CY 1  that possesses the property of being able to convert a temperature change and pressure wave into an electrical signal proportional to the amount of change. This signal is amplified by a two-stage amplifier including the transistors Q 3  and Q 7  and the microprocessor is programmed so that upon receipt of the “blow” signal from the transducer CY 1 , the transistor Q 6  is turned off, thereby extinguishing LED 1 . 
       FIG. 7  is an electrical schematic diagram of the circuitry used to simultaneously recharge the batteries of a plurality of artificial candles heretofore described. The 110 volt AC to 12 volt DC adapter  12  provides its output to the current limitator circuit  14  contained within the broken line box  110 . The current limitator circuit functions to limit the current draw by the attached charging trays to a maximum of 3.2 amperes and thereby preventing overloading of the adapter  12 . Should the current draw by the connected recharging trays reach the limit of 3.2 amperes, the current limitator automatically cuts off the power being delivered to the recharging trays. The current limitator circuit includes a Type TL431 shunt regulator  112  whose cathode and reference electrode are connected through a jumper selectable voltage divider to the non-inverting input of an LM393 operational amplifier  114  and whose output connects to a Type IRFL024N power MOSFET operatively connected between a wire in the cable that is adapted to plug into the charging tray and ground. The inverting input of the op amp  114  connects through a manually operated reset switch  118  to ground. 
     The cathode electrode of the shunt regulator  112  is also coupled through a resistor  120  to the non-inverting input of an operational amplifier  122 . The resistor  120  along with a further resistor  123  constitutes a voltage divider. The cathode electrode of the shunt regulator  112  also connects through a parallel RC circuit  124  to the inverting input of the op amp  122 . The op amp  122  has its output electrode connected through a diode  126  to the inverting input of the op amp  114  and through a resistor  128  to the gate electrode of the power MOSFET  116 . 
     Those skilled in the art will appreciate that the shunt regulator  112  functions much like a Zenar diode to provide a predetermined reference for the op amps  114  and  122  and that when the current being drawn from the AC/DC adapter  12  approaches 3.2 ampere, the power MOSFET  116  is driven into conduction effectively disconnecting the AC/DC adapter source from its load. 
     The recharging tray circuits are shown enclosed by broken line boxes  130  and  133 . While only two such recharging tray circuits are shown in  FIG. 7 , it is to be appreciated that additional trays may be concatenated by operatively joining them to the two conductor cable  132 , via plugs as at  134  and  136 , that are adapted to mate with sockets or jacks  138  and  140 , respectively, in the manner explained with reference to  FIG. 1B . In that the two illustrated recharging trays are identical, it will only be necessary to explain the constructional features of one of them and, in this regard, attention will be given to the circuitry shown enclosed by the broken line box  130 . 
     With the plug  134  mated with the jack  138 , a current path is established to a conductor  142  that connects to the center tap terminals of the primary windings of transformers T 1  through T 12 . It will be recalled that the cores of the transformers T 1 -T 12  are individually disposed within hollow posts projecting upward from the center of the pockets on the charging tray. The “ON” state of the charging tray is indicated by means of a pair of LEDs  144  connected between conductor  142  and ground. 
     The two outer terminals of the center tapped windings of transformers T 1  through T 12  are connected through, for example, MOSFET switches  146 ,  147 ,  148 , and  149 , and the ON/OFF state of these switches is controlled by one of the pulse width modulator chips  150  and  152 . Without limitation, they may each comprise a Type SG3525A integrated circuit device available from ST Microelectronics or an ESM6820A dual N-Channel enhancement mode FET. Such circuits are frequently used in the design of various types of switching power supplies. Thus, the duty cycle of the pulsitile current made to flow through the transformer windings of T 1  through T 12  can be controlled. To protect the MOSFET switches  146 - 149  from exposure to peak voltages generated by the coils of the transformer windings, a diode  153  and a parallel RC circuit  155 ,  157  is connected between the outer ends of the coils and their center tap. 
     The switching rate of the MOSFET switches  146 - 149  is controlled by the selection of the RC time constant of the circuit connected to the “R” and “C” input terminals of the integrated pulse width modulator chips  150  and  152 . The RC timing circuit for the pulse width modulator chip  150  is identified by numeral  154  in  FIG. 7 . 
     When the artificial candles are placed on the recharging tray in the manner shown in  FIG. 4 , the winding contained within the candle housing is exposed to the magnetic flux generated by the transformer coils of T 1 -T 12  and converted by the rectifiers D 201  and D 202  to a DC current for recharging the candles&#39; batteries  24 . 
     The microprocessor chip U 1  contained within the candle causes the battery to be charged with only 30% of the maximum set current for a period of 20 minutes. Following that, the batteries in the candles will be charged at 100% of the set current until such time that it is detected that the battery voltage has reached 4.2 volts, indicating a fully charged condition. At this time, the glowing red LED (LED  2 ) will switch off and the green LED (LED  3 ) is illuminated to indicate a fully charged condition of the candle battery. As already mentioned, the microprocessor U 1  in the candle receives a signal when the battery has become fully charged up to 4.3 volts and will cause the transistor Q 1  to become non-conductive, thereby cutting off the charging current. 
     This invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use such specialized components as are required. However, it is to be understood that the invention can be carried out by specifically different equipment and devices, and that various modifications, both as to the equipment and operating procedures, can be accomplished without departing from the scope of the invention itself.

Technology Classification (CPC): 7