Abstract:
A device comprising energy saving circuitry incorporated within lighting systems of the type utilizing discharge lamps, wherein the circuitry includes at least one transformer having a primary and secondary windings oppositely wound to establish different fields of polarity. The primary winding is connectable across a supply voltage and the secondary winding is connected in series with the discharge lamps) load. A switching assembly is associated with each of the one or more transformers and is operative in a first position to connect the primary winding across the supply voltage, wherein a voltage of an opposite polarity is induced across the secondary winding. In a second operative position the one or more switch assemblies serve to disconnect the primary winding from across the supply and to shunt the primary winding, so that voltage across the secondary winding is zero (v).

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention is directed to circuitry structured to control the supply voltage to electric lighting systems of the type incorporating discharge lamps, hereinafter referred to as “discharge bulbs”, “discharge lamps” and/or “bulbs”.  
         [0003]     2. Description of the Related Art  
         [0004]     The use of discharge bulbs is increasingly popular for a variety of applications in the lighting or illumination industry. Such increased acceptance and utilization is due, at least in part, to economical reasons. Minimum power consumption per lumen compares favorably as compared to lighting or illuminating systems utilizing other lighting elements such as, but not limited to, incandescent and gas lamps.  
         [0005]     However, it has long been known that inherent economic and operational disadvantages, resulting in the waste of electrical energy in many circuit structures and/or designs associated with conventional illumination systems, are due to the believed necessity of inductive loads. Such inductive loads play a role during the ignition and operational phases of the bulb or lighting element. Moreover, such operational or performance characteristics have no functional benefit other than limiting or restricting electrical current. Therefore, the presence of an inductance in the manner herein described comprises a constant ohmic and inductive resistance, causing energy loss through heat dissipation. Also, the amount of energy wasted is directly proportional to the current value flowing therethrough.  
         [0006]     In order to gain a better understanding and appreciation of the problems and disadvantages associated with conventional illumination system circuitry of the type described, as well as a proposed solution, an examination of a prevalent and/or conventional single phase bulb, lighting circuit, is schematically represented in the prior art circuit of  FIG. 1 . As shown, the prior art system comprises the primary supply voltage VPN powering the lighting circuit which also includes bulb B, inductance L and capacitor C. The capacitor C is included for adjusting the power factor of the ignition circuit.  
         [0007]     Assuming that the bulb B is of a conventional type, such as a 150 W General Electric® Sodium high pressure bulb, it is known that the rated operating voltage thereof is 113V. However, the rated primary voltage is 230V. Obviously, the voltage drop over inductance L must be 230VAC−113VAC=200VAC. It can therefore be shown that the impedance of the inductance L is calculated and designed so that the current through the bulb B, under the above conditions, is 0.88 A. However, tests have proven that the bulb B will continue to properly function (not become extinguished) even when the voltage drop there across is lowered to 109V. Such a reduced operating voltage results in a reduction in operating current of 0.62 A, while using the same inductance L.  
         [0008]     The following table summarizes the results of tests conducted with the 150W GE® Sodium bulb:  
                       TABLE 1                       VPN (v)   VL (v)   Ia(A)                   230   113   .88       225   113   .35       220   113   .83       215   113   .81       210   112   .76       205   111   .72       200   110   .67       195   109   .62                  
 
         [0009]     The total consumption of the bulb B at a full supply voltage is 230×0.88=202 VA, and total energy consumption at the reduced voltage is 195×121 VA.  
         [0010]     Hence, it is apparent that by reducing the input voltage by 230−195=35V (or 15%) the voltage drop on the inductance L is reduced from 200 VAC to 140 VAC, or by about 30%. Accordingly, the key for reducing the dissipated energy loss may be found in the non-linear relationship between the input voltage and the current flow through the bulb.  
         [0011]     Various attempts have been made to accomplish the reduction of the main voltage to a minimum acceptable level without derogatorily affecting the bulb, such as by extinguishing the bulb after ignition or starting of the ionization process. However, none of the known or conventional attempts have proved to be successful, for a variety of reasons. By way of example, one such attempt incorporates the use of variac rheostats, tap changer transformers, inverters, and other devices. Such attempts are generally considered to be less than satisfactory because of, among other reasons, the step-like nature of the process and the fact that such devices are bulky, expensive and less than operationally reliable, demanding relatively frequent maintenance.  
         [0012]     Accordingly one broad object of the present invention is to provide a method of and devices for controlling the input voltage supply of bulb lighting circuits that will effectively overcome the deficiencies of known or conventional circuitry.  
         [0013]     It is a further object of the invention to provide a transformer-based switching system that will achieve the reduction of the input voltage in an effective manner.  
         [0014]     It is a still further object of the invention that a switching system, as proposed herein, be readily operable by remote and/or possibly computerized means.  
       SUMMARY OF THE INVENTION  
       [0015]     The present invention is directed to controlling the level of a supply voltage applied to a load, in particular one or more discharge lamps or bulbs associated with a lighting or illumination system through the utilization of customized circuitry. Accordingly, at least one preferred embodiment of the present invention comprises circuitry, as described in detail hereinafter, including at least one transformer having a primary winding being connectable across the supply voltage and a secondary winding being connected in series with the load. Further, a switching assembly is provided and operatively structured to be disposed in a first position serving to connect the primary winding across the supply voltage, thereby providing a voltage having an opposite polarity being introduced across the secondary winding of the transformer. Moreover, the switching assembly being disposed in a second position serves to disconnect the primary winding from across the supply voltage and to shunt the primary winding so that voltage across the secondary winding is zero (V).  
         [0016]     Other preferred embodiments of the present invention preferably include, a modification of the control circuitry to include two or more transformers each operatively associated with a separate switching assembly. Further, the switching assemblies are structured for independent and selective actuation preferably in succession, so that the minimum operable voltage is attained progressively.  
         [0017]     These and other objects, features and advantages of the present invention will become clearer when the drawings as well as the detailed description are taken into consideration. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]     For a fuller understanding of the nature of the present invention, reference should be had to the following detailed description taken in connection with the accompanying drawings in which:  
         [0019]      FIG. 1  is a schematic diagram of a conventional prior art discharge bulb lighting circuit.  
         [0020]      FIG. 2  is a schematic diagram of a single-phase circuit featuring the principles of one preferred embodiment of the present invention.  
         [0021]      FIG. 3  is a schematic diagram of a circuit, similar to the embodiment of  FIG. 2 , for attaining a gradual decrease of the voltage applied to the discharge bulb and representing yet another preferred embodiment of the present invention.  
         [0022]      FIG. 4  is a three-part composite schematic diagram of circuitry illustrating a three-phase primary voltage supply and representing yet another preferred embodiment of the present invention.  
         [0023]      FIG. 5  is a schematic diagram of circuitry representing yet another preferred embodiment of the present invention. 
     
    
       [0024]     Like reference numerals and letter designations refer to like parts throughout the several views of the drawings.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0025]     As disclosed in  FIG. 2 , one preferred embodiment of the present invention comprises a circuit which includes a transformer T having primary winding W 1  and secondary winding W 2 . The transformer T comprises a “voltage subtraction” configuration, at least partially defined by the secondary winding W 2  inducing a field of a polarity opposite to that of the primary winding W 1 . This is attained by reversing the winding directions of the windings W 1  and W 2  relative to each other.  
         [0026]     The entrance side of both the primary and the secondary windings W 1  and W 2  are connected to each other at connection a. The exit side of the primary winding W 1  is branched as shown and thereby configured to define or be connected to one pair of terminals t 1  and t 2 . A double-throw, double pole switch assembly S is schematically represented and includes contacts s 1  and s 2  structured and positionable to establish a connection between terminals t 1  and t 3 . Such an established connection serves to break contact between terminals t 2  and t 4 , when the switch assembly S is in a first operative position. A second operative position of the switch assembly S is the opposite of the first operative position and establishes a connection between terminals t 2  and t 4  and breaks contact between terminals t 1  and t 3 . The exit side of the secondary winding W 2  is connected in series with the inductance L, as represented in the conventional or prior art circuitry of  FIG. 1 , as are the remaining components including bulb B and capacitor C.  
         [0027]     The switch assembly S may be of the electromechanical relay type. However any other switching arrangement is equally applicable for the purposes of being operative in the various preferred embodiments of the present invention. Such additional appropriate switching assemblies may include, but are not intended to be limited to, electronic switch assemblies which preferably, but not necessarily, include remote control capabilities.  
         [0028]     Operation of the circuit of the preferred embodiment of  FIG. 1  is as follows. At the beginning, when the bulb B is to be activated or ignited, the switch assembly S is set in the first operative position, as set forth above, wherein terminals t 2  and t 4  are connected and terminals t 1  and t 3  are disconnected. It can readily be seen that the primary supply voltage VPN will be applied across the bulb B, as required for ignition or activation thereof. This is achieved since the primary winding W 1  is shunted resulting in a situation known as “self-saturation” to prevail, as relates to the transformer T. The voltage across points e and f (Vef) is thus almost equal to the mains voltage VPN. Hence, the voltage across the secondary winding W 2  of the transformer T is forced to approach zero (v).  
         [0029]     However, in order to reduce amperage passing the inductance L, which is a concern and one operative feature of the present invention, switch assembly S is oriented to assume its second operative position. As set forth above, the second operative position of the switch assembly S comprises the terminals t 1  connected to t 3  and terminals t 2  disconnected from t 4 . The primary winding W 1  is therefore subjected to the full supply voltage VPN, including voltage VW 2  over the secondary winding W 2 . Since the field polarities are opposite as set forth above, the voltage Vef across points e-f is reduced by the value of VW 2  compared with the supply voltage VPN. Consequently, the current passing inductance L and the bulb B is reduced by the same amount and with it the power consumption of the inductance L. It is recognized that certain resistance losses associated with the winding W 2  are present but are substantially negligible in a practical application.  
         [0030]     Accordingly it should be apparent that by suitably selecting the step-down ratio of the transformer T (W 1 :W 2 ), the minimum operable “target” voltage of 195 V can be achieved (see Table 1 above) with the resulting 30% savings in energy. In the preferred embodiment of  FIG. 2 , this means that the secondary winding W 2  is calculated to subtract 35 V from the primary supply voltage of 230v.  
         [0031]     In order to avoid the possibility of the discharge bulb B becoming extinguished, because of an abrupt and/or significant reduction of the operating voltage being applied thereto (from 230V to 195V), an additional preferred embodiment schematically represented by the circuit diagram of  FIG. 3  is proposed. Essentially, the difference between the structure and operation of the circuit of  FIG. 3  as compared with that of  FIG. 2  comprises the utilization of multiple transformers T 1 , T 2 , and T 3  each operatively connected in direct association with corresponding ones of the plurality of switch assemblies S 1 , S 2 , and S 3 . As such, a more suitable control of the switch assemblies S 1 , S 2 , and S 3  is possible resulting in a progressive or more gradual reduction of the voltage applied to the bulb B.  
         [0032]     It will be readily understood that, by denoting the voltage reduction amount of the transformers T 1 -T 3  by R 1 -R 3  respectively, any of the following combinations regarding the voltage applied to the bulb B (VB) can be attained: 
 
VP=VPN 
 
 VB=VPN−RL  
 
 VP=VPN−R 2 
 
 VP=VPN−R 3 
 
 VP=VPN −(R1+ R 2) 
 
 VP=VPN −( R 1+ R 3) 
 
 VP=VPN −( R 2+ R 3) 
 
VP=VPN−( R 1+ R 2+ R 3) 
 
         [0033]     Therefore, by suitably programming the sequence of actuations of the switches S 1 -S 3 , any of the above listed results is attainable. Applying this technique to the above example, it would be convenient to choose the following values: 
 
R 1 =5V 
 
R 2 =10V 
 
R 3 =20V 
 
 Accordingly, at the beginning of operation relating to the ignition or activation stage, all switches will be their “first operative position” as above described, wherein the full voltage VPN (230 V) will be applied to the bulb B. 
 
         [0034]     The following summarizes the subsequent operational steps:  
                                                   SWITCHES OPERATED   VOLTAGE ON BULB VB                           S2   220           S1 + S2   215           S3   210           S1 + S3   205           S2 + S3   200           S1 + S2 + S3   195                      
 
         [0035]     By applying this sequence of switch assembly actuations, the effective bulb operating voltage will be progressively decreased by increments of 5V, as indicated. It is further noted that these switch assembly actuations can be controlled by computerized and/or remote facilities.  
         [0036]     Yet another preferred embodiment of the present invention is schematically demonstrated by the composite circuitry of  FIG. 4 . As indicated, this preferred embodiment of the present invention is directed to a three phase electric supply line, P 1 , P 2  and P 3 . For purpose of clarity, the transformers and switching devices are schematically presented in block diagram form and collectively designated as TS 1 , TS 2 , TS 3 . It is to be understood that each block represents a cooperative structuring of one transformer and an associated switch assembly, as described above with reference to the embodiment of  FIG. 3 . Moreover, the individual bulb voltage control circuit of each phase operates in the same manner as described with reference to the embodiment of  FIG. 3 .  
         [0037]     However included in the preferred embodiment of  FIG. 4  is the addition of bypass ON/OFF switches SP 1 , SP 2  and SP 3 . Switches SP 1   a,  SP 1   b,  SP 2   a,  SP 2   b,  and SP 3   a,  SP 3   b  are also provided. These may be included for protecting the respective transformers and/or, the load or discharge bulbs B against overloading and short-circuiting, respectively.  
         [0038]     Yet another preferred embodiment of the present invention is schematically represented in the circuit assembly of  FIG. 5 . More specifically, as described above with reference to the embodiments of  FIGS. 2 through 4 , the voltage reduction was achieved by the activation of one or more power transformers having a secondary winding connected in series with the inductance L. However, in the preferred embodiment of  FIG. 5  the voltage reduction process is inverted and accomplished through the deactivation of power transformers, as set forth in greater detail hereinafter.  
         [0039]     Advantages of the embodiment of  FIG. 5 : 
        The maximum reduction in voltage, which is directly related to energy consumption reduction, can be achieved when the power transformers are deactivated, there is less heat coming out of the unit. Therefore, forced ventilation is reduced resulting in greater efficiency.     With this type of internal operation mode, it is possible to work with voltages higher than 277V, which was the highest possible so far. This is possible since there is no high cross voltage in the contacts or terminals of associated switch assemblies.        
 
         [0042]     While the previously described embodiments are unique and clearly distinguishable from related known or conventional control circuitry, especially in terms of power efficiency, certain limitations may be present, such as applications relating to voltages higher than 240V (L−N). Moreover, certain lighting applications are built to work at higher voltages such as: 
 
3×277v+/−10% which is 249-305V (L−N) in the U.S.A. 
 
1×480v+/−10% 432-528v (L−L) in the U.S.A. 
 
3×347v+/−10% 312-381v (L−N) in Canada 
 
         [0043]     Accordingly the improvement of the preferred embodiment is intended to withstand a higher voltage range from generally about 120v to 528v. Any limitation due to commutation energy being developed on the switching contacts of the “MINI CELL” transformers −5v, 10v, 20v is thereby overcome. With primary reference to  FIG. 5 , the preferred embodiment comprises feeder transformers (mini cells) A, B, and C, as well as a booster transformer D.  
         [0044]     Each of the feeder transformers A, B and C switched between two modes comprising a reduced, defined voltage and zero voltage. Also, the feeder transformers A, B and C are wound in negative direction to the main and combined in a binary sequence.  
         [0045]     For example, the three feeder transformers A, B and C will provide 8 levels of continuous voltages to the Booster transformer D. In that these feeder transformers are wound negatively between the net and primary winding of the booster transformer D, the output voltage may be controlled or regulated.  
         [0046]     By way of example:  
                                                       Feeder transformers:   A 280 V/25 V               B 280 V/50 V               C 280 V/100 V           Booster transformer:   D280 V/40 V                      
 
         [0047]     The binary combination of the feeder transformers A, B and/or C results in the following:  
                                                                                 Reduced   Voltage at   Voltage           Active   voltage to   the primary   reduction   Output       transformers   the booster   booster   to the output   voltage                                None   O V   280 V   39.5   V   241   V       A    −25 V   255 V   36   V   244   V       B    −50 V   230 V   32.5   V   247.5   V       A + B    −75 V   205 V   29   V   251   V       C   −100 V   180 V   25.5   V   254.5   V       A + C   −125 V   155 V   22   V   258   V       B + C   −150 V   130 V   18.5   V   261.5   V       A + B + C   −175 V   105 V   15   V   265   V                  
 
         [0048]     Further, the activation of each of the feeder transformers A, B and C is achieved by closing a switch or relay assembly associated with the primary winding of the feeder transformers A, B or C and opening independent or directly associated switch or relay assemblies a, b or c, as well as opening the appropriate switch or relay assemblies u 1 , v 1  and w 1  that shunts the secondary windings of the respective transformers. The deactivation is achieved by the opposite operation of the indicated and appropriate switch or relay assemblies. Accordingly, the operational and/or performance advantages especially in terms of efficiency, power transfer ratio and non wave distortion of the previously described embodiments is achievable through application of the preferred embodiment of  FIG. 5 . Further, the commutation phenomenon is resolved by not exposing the controlling switch or relay assemblies to high cross voltage.  
         [0049]     The various preferred embodiments of the present invention thus provides an extremely simple and straightforward solution to a long lasting and well recognized problems relating to the inherent waste of electrical energy associated with lighting systems incorporating discharge lamps or bulbs.  
         [0050]     While the above description is directed to appropriate specific structural and operational features, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of the preferred embodiments. Those skilled in the art will envision other possible variations that are within the intended scope of the present invention. Accordingly, the scope of the invention should be determined not by the embodiment illustrated, but by the appended claims and their legal equivalents.  
         [0051]     Since many modifications, variations and changes in detail can be made to the described preferred embodiment of the invention, it is intended that all matters in the foregoing description and shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense. Thus, the scope of the invention should be determined by the appended claims and their legal equivalents.  
         [0052]     Now that the invention has been described,