Abstract:
A power saver for discharge lamps, in which supply of electricity is not stopped instantaneously even though applied voltage is converted into lower voltage after lighting the discharge lamp, is disclosed. The power saver for discharge lamps includes a first coil, a second coil having a winding direction opposed to a winding direction of the first coil and located in an opposite direction of the first coil, an insulator located at a gap part where the first coil and the second coil are opposed, at least one or more taps arranged along a longitudinal direction of the second coil, at least one or more switches selectively connected to one of the taps, at least one or more first timers connected to the switches respectively, an electric relay mounted in a loop circuit including both end parts of the second coil, and a second timer connected to the electric relay. At the time of an initial power supply, current flows through only the first coil because the switches are all opened and the discharge lamp is lighted in a state that the electric relay is shut, and each timer is operated to shut each switch when a prescribed period of time passes after lighting of the discharge lamp is finished by the current.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a power saver for discharge lamps, and more particularly, to a power saver used in discharge lamps. 
     2. Background of the Related Art 
     Fluorescent lamps, mercury lamps, natrium lamps, metal lamps and so on are generically called discharge lamps because using light obtained through electric discharge after the electric discharge is made by gas filling the inside of the lamp. 
     Such discharge lamp generally needs a predetermined voltage of 220V or 100V to start the electric discharge. However, the discharge lamp can radiate light without any trouble even though lower voltage is applied to the discharge lamp to maintain the electric discharge after the discharge lamp is discharged and lighted. Therefore, for example, a large-sized sign board using 1400˜1500 natriums at once has a considerable power-saving effect when voltage is applied at 80˜90% of initial voltage in the discharge maintaining step. 
     In consideration of the above, a power saver, which shows the power-saving effect by applying lower voltage after starting electric discharge by supplying voltage of 220V (or 110V) when a discharge lamp is lighted, and applies lower voltage to the discharge lamp after completing the electric discharge, thereby showing power-saving effect, has been well known. However, the power saver of the above type is a simple form to which an automatic transformer is applied. Such power saver cannot be spread widely because it happens very often that supply of electricity is instantaneously cut off and the discharge lamp does not lighted again after being lighted out when voltage is converted into lower voltage after starting the discharge. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to a power saver for discharge lamps that substantially obviates one or more problems due to limitations and disadvantages of the related art. 
     An object of the present invention is to provide a power saver for discharge lamps in which supply of electricity is not cut off and of which volume is small and manufacturing expenses are inexpensive even though applied voltage is converted into lower voltage after the discharge lamp is lighted. 
     Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
     To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a power saver for discharge lamps including a first coil, a second coil having a winding direction opposed to a winding direction of the first coil and located in an opposite direction of the first coil, an insulator located at a gap part where the first coil and the second coil are opposed, at least one or more taps arranged along a longitudinal direction of the second coil, at least one or more switches selectively connected to one of the taps, at least one or more first timers connected to the switches respectively, an electric relay mounted in a loop circuit including both end parts of the second coil, and a second timer connected to the electric relay. At the time of an initial power supply, current flows through only the first coil because the switches are all opened and the discharge lamp is lighted in a state that the electric relay is shut, and each timer is operated to shut each switch when a prescribed period of time passes after lighting of the discharge lamp is finished by the current. 
     It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings; 
     FIG. 1 illustrates a circuit diagram of a conventional power saver for discharge lamps; 
     FIG. 2 illustrates a circuit diagram of a power saver for discharge lamps according to a first preferred embodiment of the present invention; 
     FIG. 3 illustrates a circuit diagram of a modification of the power saver for discharge lamps according to the first preferred embodiment; 
     FIG. 4 illustrates a circuit diagram of a power saver for discharge lamps according to a second preferred embodiment of the present invention; and 
     FIG. 5 illustrates a circuit diagram of a power saver for discharge lamps according to a third preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. For your understanding, first, a conventional power saver for discharge lamps will be described. 
     FIG. 1 illustrates a simple circuit diagram of an inner structure of the conventional power saver for discharge lamps applying an automatic transformer. The conventional power saver for discharge lamps includes only one coil C and a plurality of taps T 1 , T 2 , T 3  and T 4  arranged along a longitudinal direction of the coil C. The circuit of the conventional power saver for discharge lamps includes first and second switches S 1  and S 2 , and the second switch S 2  is connected to one predetermined tap (tap T 3  in FIG. 1) of the above taps. As shown in a dotted line in the drawing, a pair of terminals P 1  and P 2  are connected to an external power supply system E and another pair of terminals P 3  and P 4  are connected to a discharge lamp L 1 . The reference mark ST designates a stabilizer, and the first and second switches S 1  and S 2  are connected to a timer (T). 
     In such power saver for discharge lamps, the first switch S 1  is shut and the second switch S 2  is open in an initial stage for lighting the discharge lamp. Therefore, when electric power is applied from the external power supply system, the discharge lamp L 1  is charged with electricity through the circuit including the first switch S 1 , thereby starting the electric discharge. When the electric discharge of the discharge lamp L 1  is finished and lighted, the first switch S 1  is opened and the second switch S 2  is shut by the operation of the timer (T). Here, the coil C serves as an automatic transformer. When the first switch S 1  is opened and the second switch  2  is shut, voltage after passing the automatic transformer, i.e., the coil C, is lowered compared with voltage applied from the outside. As described above, because the plurality of taps T 1 , T 2 , T 3  and T 4  are mounted in the coil C, the strength of voltage is changed according to whether the second switch S 2  is connected to which tap. As the result, the strength of voltage is changed according an available winding number of the coil. 
     However, in such power saver for discharge lamps, because a branch circuit including the coil C is short-circuited and damaged in a condition that the first and second switches S 1  and S 2  are simultaneously shut, it must be always kept that the first switch S 1  is first opened and then the second switch S 2  is shut when the first and second switches S 1  and S 2  are converted in their opening and shutting. Therefore, the supply of electricity is cut off instantaneously when the first and second switches S 1  and S 2  are converted in their opening and shutting, and at this time, it happens frequently that the discharge lamp is lighted off and is not lighted again. 
     Hereinafter, various preferred embodiments of a power saver for discharge lamps according to the present invention applying the automatic transformer to solve the above problems will be described. 
     FIG. 2 illustrates a power saver  1  for discharge lamps according to a first preferred embodiment of the present invention, and FIG. 3 illustrates a modification  1 ′ of the first preferred embodiment. As shown in the drawings, because the power saver  1  includes a pair of coils C 11  and C 12  having different directions from each other and an insulator INS located at the center thereof, and the pair of coils C 11  and C 12  serve as the automatic transformer having subtractive polarity. 
     At least one or more taps T 11 , T 12 , T 13  and T 14  are mounted along a longitudinal direction of the second coil C 12 , and one of the taps (tap T 13  in the drawings) is connected to a switch S 11 . In case that the plurality of taps are mounted in the second coil C 12 , that the switch is connected to which tap is determined according to whether voltage for maintaining the electric discharge is set at what percent of the initially applied voltage. Furthermore, in case that only one tap is mounted to the second coil C 12 , that the tap is mounted at which place of the second coil C 12  is also determined according to whether voltage for maintain the electric discharge is set at what percent of the initially applied voltage. This will be described in more detail as follows. 
     A pair of terminals P 11  and P 12  are connected to the external power supply system E shown in the dotted line in the drawing, and another pair of terminals P 13  and P 14  are connected to a discharge lamp L 11 . The reference mark ST designates a stabilizer, and a switch S 11  is connected to a timer (not shown). 
     The switch S 11  is opened in an initial stage for lighting the discharge lamp, and therefore, when power supply is applied from the outside, the electric discharge of the discharge lamp L 11  is started through a closed circuit (hereinafter, called “main circuit”) including the first coil C 11 , but the second coil C 12  is not charged with electricity. Like that, when the discharge lamp L 11  is lighted, electricity continuously flows through the main circuit in a state that the switch S 11  is shut, because a switch corresponding to the first switch S 1  shown in FIG. 1 does not exist. Therefore, the circuit is not instantaneously opened or the discharge lamp L 11  is not lighted out. 
     Continuously, the moment the switch S 11  is short-circuited by the operation of the timer, the switch S 11  is connected to one predetermined tap of the taps. The switch S 11  is naturally connected to one preset tap when the second coil C 12  has only one tap. However, means for selecting or changing a tap to be connected with the switch must be provided in case that the second coil has the plural taps. It is preferable that the selecting means is a selector switch as shown in FIG.  2 . Alternatively, as shown in FIG. 3, it will be appreciated that a plurality of switches S 111 , S 112 , S 113  and S 114  corresponding to the number of the taps are mounted and only one predetermined tap of them is shut. 
     If the switch S 11  (or one of the switches S 111  through S 114 ) is short-circuited, the coils C 11  and C 12  serve as the automatic transformer, and the coils C 11  and C 12  generate induction voltage to the second coil C 12  due to a winding direction different from each other. The strength of induction voltage may be changed according to whether the switch is connected to which tap of the taps T 11  through T 14 , as being changed according to a winding ratio of the first coil C 11  and the second coil C 12 . 
     For example, in this specification, a winding part of the first coil C 11  is designated as n 1  and the number of the whole windings of the second coil C 12  is designated as n 2 . The number of the taps is N. If the N taps are arranged at regular intervals, the winding number between the taps is n 2 /(N−1). In this embodiment shown in the drawing, four taps are mounted and the switches S 11  and S 113  are connected to the third tap T 13 . In this case, the available winding number of the second coil becomes n 2 ×(2/3)=2n 2 /3. In other words, as the wining ratio of the first coil C 11  and the available second coil C 12  becomes n 1 /[2n 2 /3]=3n 1 /2n 2  the strength of the induction voltage becomes 3n 1 /2n 2 ×E (induction voltage). Therefore, after the switches S 11  and S 23  are shut, voltage corresponding to the difference between the induction voltage and the applied voltage is supplied to the discharge lamp L 11  through the main circuit. Because the strength of the induction voltage is changed according to whether the switch is connected to which tap of the taps T 11  through T 14 , voltage supplied to the discharge L 11  is lower than the applied voltage E. 
     FIG. 4 illustrates a power saver  2  for discharge lamps according to a second preferred embodiment of the present invention. The power saver  2  for discharge lamps according to the second preferred embodiment is similar to the power saver  1  of the first preferred embodiment shown in FIG.  2 . In other words, in the same way of the power saver  1  for discharge lamps according to the first preferred embodiment, also the power saver  2  for discharge lamps of the second preferred embodiment includes a pair of coils C 21  and C 22  having a different winding direction from each other and an insulator INS mounted at the center thereof. Furthermore, a plurality of taps T 21 , T 22 , T 23  and T 24  are mounted to the second coil C 22 , and a switch (hereinafter, called a “first switch”) S 21  selectively connected to one of the taps T 21  through T 24 . Moreover, a pair of terminals P 21  and P 22  are connected to an external power supply system E shown in a dotted line in the drawing, and another pair of terminals P 23  and P 24  are connected to a discharge lamp L 21 . The reference mark ST designates a stabilizer, and a switch S 21  is connected to a timer (T). 
     However, a difference between the power saver  2  of the second embodiment and the power saver  1  of the first embodiment is that another switch (hereinafter, called a “second switch”) S 22  coupled to the timer (T) is added to a circuit including the first coil C 22 . The power saver  2  of the second embodiment can have the same effect as the power saver  1  of the first embodiment even though the switch S 22  is added to the power saver  2  of the second embodiment. That is, even though the power saver  2  of the second embodiment is used, the circuit is not opened instantaneously or the discharge lamp is not lighted out, and voltage lower than the applied voltage can be continuously supplied to the discharge lamp. 
     In more detail, the first switch S 21  is opened and the second switch S 22  is short-circuited in an initial stage for lighting the discharge lamp L 21 . Therefore, power supply applied from the outside is applied to the discharge lamp L 21  with voltage of the same level as the applied voltage E through a closed circuit including the second S 22 , but the second coil C 22  is not charged with electricity. When the discharge lamp L 21  is lighted, the first switch S 21  is short-circuited and the second switch S 22  is opened by the operation of the timer (T). The circuit is not opened instantaneously or the discharge lamp L 21  is not lighted off because voltage lower than the applied voltage E is continuously supplied to the discharge lamp L 21  through the first coil C 21  even though the first switch S 21  is short-circuited and the second switch S 22  is opened. 
     As described above, when the second switch S 22  is opened and the first switch S 21  is short-circuited, voltage lower than the applied voltage E is continuously supplied to the discharge lamp L 21  in the same way as the power saver  1  of the first embodiment. The reason is that the coils C 21  and C 22 , which are components of the power saver  2  for discharge lamps, serve as the automatic transformer having subtractive polarity in the same way as that of the power saver  1  of the first embodiment. Therefore, because the strength of induction voltage is changed according to whether the switch S 22  is connected to which tap of the taps T 21  through T 24 , also voltage supplied to the discharge lamp L 21  is supplied in a lower level than the applied voltage E. Additionally, it is not shown in the drawings, but it will be appreciated that a modification, which is the same as the modification of the power saver  1  of the first embodiment (see FIG. 3) may be applied to the power saver  2  for discharge lamps of the second embodiment. That is, switches are mounted corresponding to the number of the taps of the power saver  2  for discharge lamps of the second embodiment, and only one predetermined tap is shut. 
     FIG. 5 illustrates a power saver for discharge lamps according to a third preferred embodiment of the present invention. As shown in FIG. 5, the power saver  3  for discharge lamps of the third embodiment is similar to the power saver  2  for discharge lamps of the second embodiment. In other words, the structure of the power saver  3  for discharge lamps is the same as the power saver  2  for discharge lamps besides the second switch S 22 , and the same as the power saver  1  for discharge lamps of the first embodiment. Therefore, the structure of the power saver  3  for discharge lamps of the third embodiment, which is the same as the power saver  2  for discharge lamps of the second embodiment will not be described. 
     However, the power save  3  for discharge lamps of the third embodiment has an electric relay  10  serving the same function as the second switch S 22  mounted in the power saver  2  for discharge lamps of the second embodiment. The electric relay  10  performs the same function as the second switch S 22  but has advantages that its volume is small in volume and expenses are inexpensive. Therefore, the third embodiment shows the power saver for discharge lamps using the electric relay  10 , which is small in volume and inexpensive in expenses, instead of the second switch S 22  (for example, a magnetic switch), which is large in volume and somewhat expensive in expenses. 
     Referring to FIG. 5, the power saver  3  for discharge lamps according to the third embodiment will be described in more detail as follows. The power saver  3  for discharge lamps has the same structure as the power saver  2  for discharge lamps of the first embodiment, and the same structure as the power saver  2  for discharge lamps besides the second switch S 22 . The electric relay  10  is mounted between a second coil C 32  and one (tap T 34  in the drawing) of taps T 31  through T 34 , and a timer (T) is connected to the electric relay  10 . 
     In the above structure, a switch S 31  is opened and the electric relay  10  is short-circuited in an initial stage for lighting a discharge lamp L 31 . Therefore, when power supply is applied from the outside, the discharge lamp L 31  is discharged through a closed circuit including a first coil C 31  and the electric relay  10 , but a second coil C 32  is not charged with electricity. When the discharge lamp L 31  is lighted, a switch S 31  is short-circuited and the electric relay  10  is opened by the operation of the timer (T). The circuit is not opened instantaneously or the discharge lamp L 31  is not lighted out because voltage is continuously supplied to the discharge lamp L 31  through the first coil C 31  even though the electric relay  10  is opened and the switch S 31  is short-circuited. 
     As described above, when the electric relay  10  is opened and the switch S 31  is short-circuited, voltage lower than the applied voltage E is continuously supplied to the discharge lamp L 31  in the same way as the power savers  1  and  2  of the first and second embodiments. The reason is that the coils C 31  and C 32 , which are components of the power saver  3  for discharge lamps, serve as the automatic transformer having subtractive polarity, in the same way as the power savers  1  and  2  of the first and second embodiments. Therefore, because the strength of induction voltage is changed according to whether the switch S 31  is connected to which tap of the taps T 31  through T 34 , also voltage supplied to the discharge lamp L 31  is supplied in lower level than the applied voltage E. Furthermore, it is not shown in the drawings, but it will be appreciated that a modification, which is the same as the modifications of the power savers  1  and  2  of the first and second embodiments may be applied to the power saver  3  for discharge lamps of the third embodiment. That is, switches are mounted corresponding to the number of the taps of the power saver  3  for discharge lamps of the second embodiment, and only one predetermined tap is shut. 
     In the above description, for your understanding, four taps are arranged at regular intervals, but the number of the taps may be selected according to a user&#39;s desire, and the arrangement of the taps is not restricted to the regular interval and the taps may be arranged at discretionary intervals to make a prescribed output voltage (difference between the applied voltage and induction voltage) possible. 
     Moreover, if you want not to adjust output voltage at need but to fix in a set voltage, only one tap may be mounted. In this case, that the one tap is mounted at which place of the second coil may be determined in such a manner that the strength of induction voltage is calculated from desirable output voltage (that is, induction voltage=applied voltage−desirable output voltage), and available winding number is calculated back from it. 
     As described above, according to the present invention, because the switches S 11 , S 21  and S 31  are opened in the initial stage for discharging and lighting the discharge lamp, the applied voltage is supplied to the discharge lamp in the same level or lower level, and thereby the electric discharge is made without any trouble. After the electric discharge, the switches are shut, and voltage lower than the applied voltage is continuously supplied to the discharge lamp by generating induction voltage by the pair of coils, thereby obtaining good power-saving effect. 
     As described above, the power saver for discharge lamps has the power-saving effect by applying voltage lower than the applied voltage in the process for maintaining the electric discharge and the radiation of the discharge lamp after lighting and discharging the discharge lamp by the applied voltage from the outside. Additionally, in the power saver according to the present invention, the discharge lamp is not lighted out because the circuit maintains the electrically charged condition without opening of the circuit even though voltage is changed from the discharge starting stage to the discharge maintaining stage. 
     Differently from the conventional power saver applying the principle of the automatic transformer, the power saver for discharge lamps according to the present invention is more stable and has excellent power-saving effect because compensating loss using the principle of the automatic transformer. 
     The forgoing embodiments are merely exemplary and are not to be construed as limiting the present invention. The present teachings can be readily applied to other types of apparatuses. The description of the present invention is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art.