Abstract:
Disclosed is an energy-conserving device for an illumination system. The energy-conserving device is connected between a power supply of and a lighting assembly of the illumination system. The energy-conserving assembly provides a first switch, a ballast, and a compensating capacitor. The ballast is connected between the power supply and the lighting assembly, and connected between the first terminal and the second terminal of the first switch. The compensating capacitor is connected between the power supply and a third terminal of the switch. The energy-conserving device may further include a resistor and a second switch which are connected in parallel with the ballast. The energy-conserving device can be coupled to a conventional illumination system and is of energy-conserving, a low cost and a long lifetime.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of PCT Application No. PCT/CN2006/002549 filed Sep. 29, 2006, which is explicitly incorporated herein by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to an energy-conserving device of an illumination system, in particularly to an energy-conserving device employed for high intensity discharge (HID) lamps in hopes of saving energy by means of adjusting illumination intensity. 
         [0004]    2. Description of Prior Art 
         [0005]    HID lamps have been widely used as lighting sources due to its high efficiency and long service life, which are especially utilized in outdoor areas, such as roads, sports arena, supermarkets, etc. As show in  FIG. 1 , a conventional HID lamp includes a discharge light bulb  640 , a trigger  630  for initiation of electrical discharge, a ballast  610  for limiting current that passes through a bulb  60 , as well as a compensating capacitor  620  for power factor correction. Generally, the illumination intensity of the current HID lamps keeps the same, regardless of the required brightness of the illumination, therefore resulting in wasting large amount of energy. 
         [0006]    To address the shortcoming, Chinese patent No. 200420081845.x discloses a power-variable inductance ballast device. As illustrated in  FIG. 2  of the patent, an additional inductance ballast  720  is connected in parallel to an inductance ballast  710  via a tap. The power level is controlled through a switch  730  connecting each of ballasts  710  and  720  so as to alter the output power of an electrical discharging light bulb  740 . However, this solution increases the complexity of wiring of the inner circuitry. Furthermore, when the system works at different power levels, its circuitry may not match its power factor due to the limitation of the compensation capacitor. So, it is hard to reach a desirable effect of energy conservation. In addition, when the power level is switched, the system will experience a switching period. In essence, it&#39;s a power down process, which might result in collapse of arc and interruption of illuminating. To avoid this incident, it is necessary to shrink the switching period. A high-quality controller must be used for this purpose, which results in lower cost effectiveness and raises the failure rate of the product. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention is to provide an energy-conserving device which can be used to regulate the illumination intensity of an HID lamp for saving energy without changing the configuration of the existing HID lamps. 
         [0008]    Accordingly, the present invention provides an energy-conserving device used in an illumination system. The energy-conserving device is connected between a power supply assembly of the illumination system and a lighting assembly of the illumination system. The energy-conserving device comprises an energy-conserving assembly. The energy-conserving assembly comprises: a first switch having a first terminal, a second terminal and a third terminal, the first terminal configured to be optionally connected with the second terminal or the third terminal; a ballast having two terminals respectively connected to the power supply and the lighting assembly, and the two terminals further connected to the first terminal and the second terminal of the first switch, respectively; and a compensating capacitor, one terminal of which is connected to the power supply, and the other terminal is connected to the third terminal of the switch. 
         [0009]    According to a preferred embodiment of the present invention the energy-conserving assembly of the energy-conserving device may further include a second switch, and a resistor which is connected in parallel to the two terminals of the ballast after connected in series with the second switch. 
         [0010]    According to a preferred embodiment of the present invention the energy-conserving device further includes a control assembly which is connected between the power supply assembly and the switch for controlling the connection or disconnection of the switch. The control assembly may comprise a power circuit and a timing circuit, where, the power circuit provides a power source to the timing circuit and the timing circuit provides switch signals to the switch. 
         [0011]    Preferably, the power circuit of the present invention may comprise a transformer, a full wave rectifying circuit and a voltage regulating chip which are connected in series to each other. The timing circuit can be carried out by a single chip, RC circuit and so on. 
         [0012]    The control assembly may further include a power driving circuit in accordance with an preferred embodiment of the present invention, in which the switch signals generated from the timing circuit are amplified by the power driving circuit to output to the switch for controlling the connection or disconnection of the switch. 
         [0013]    The energy-conserving device employed in the present invention can implement light regulation and energy-conserving without changing a conventional lighting circuit. Moreover, the energy-conserving device of the present invention may choose the corresponding compensating capacitor depending on different light regulation states to correct a power factor. The energy-conserving device of the present invention can prolong the using life of the illumination system, ensure the lighting effect and have the advantages of low cost, easy assembling, high safety and reliability. 
     
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0014]      FIG. 1  illustrates a circuit diagram of an illumination system in the prior art; 
           [0015]      FIG. 2  illustrates a circuit diagram of an illumination system with an energy conserving device in the prior art; 
           [0016]      FIG. 3   a  illustrates a circuit diagram of an energy conserving device according to an embodiment according to the present invention; 
           [0017]      FIG. 3   b  illustrates a circuit diagram of an energy conserving device according to another embodiment; 
           [0018]      FIG. 4  illustrates a block diagram of an energy conserving device with a control module and a timer; 
           [0019]      FIGS. 5   a  and  5   b  illustrate a detailed circuit diagram of the energy conserving device as shown in  FIG. 4 ; and 
           [0020]      FIG. 6  illustrates a schematic diagram of an energy conserving device with capability for multiple operation modes. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    The present invention will be described with reference to exemplary embodiments in conjunction with the drawings. 
         [0022]    An illumination system  1000  of an embodiment of the invention is illustrated in  FIG. 3   a.  An energy conserving device  500  is connected between a power module  100  and an illumination module  200 . The power module  100  supplies power, e.g. 380V, 220V or 110V AC, to the illumination module  200 . The illumination module  200  comprises a ballast  210 , a compensating capacitor  220 , a trigger  230 , and a lighting source  240 . The compensating capacitor  220 , trigger  230 , and light source  240  are connected in parallel, while the ballast  210  is connected in serial between the compensating capacitor  220  and the trigger  230 . 
         [0023]    The energy conserving device  500  provides an energy conserving module  300  comprising a ballast  310 , a compensating capacitor  320  and a switch  330 . The ballast  310  is connected in serial between the power module  100  and the illumination module  200 . Opposite terminals  311  and  312  of the ballast  310  are connected to terminals  331  and  332  of the switch  330 , respectively. One terminal  322  of the compensating capacitor  320  is connected to the power module  100  and another terminal  321  is connected to a terminal  333  of the switch  330 . 
         [0024]    Normally, the terminals  331  and  332  of the switch  330  are conductive with each other, and the terminals  331  and  333  are disconnected. As of this configuration, the ballast  310  is short circuited and the capacitor  320  is open circuited. It means that the energy conserving device  500  is inactive and the illumination module  200  works at its full capacity with its normal intensity of illumination. 
         [0025]    When a lower intensity of illumination than the normal is tolerated, the terminal  331  and the terminal  333  of the switch  330  can be connected accordingly, resulting in disconnection of the terminal  331  and the terminal  332 . At this time, the capacitor  320  is charged. In this case, the ballast  310  is connected in serial to the ballast  210 . The ballast  310  functions to reduce the voltage to be applied to the lighting source  240  as well as limit the current to flow through the source  240 . As a result, the illumination module  200  will work in a lower-power with a lower intensity of illumination. Due to the existence of the capacitor  320 , even when the power level has reduced, the illumination system  1000  can effectively correct the power factor of the circuitry so as to improve efficiency of illumination. 
         [0026]    It&#39;s understood from  FIG. 3   a  that, in the condition that the illumination system  1000  works at a normal power, the ballast  310  is short circuited due to the connection between the terminals  331  and  332  of the switch  330 . When the change of the power level is needed, the ballast  310  works at the moment that the terminal  332  moves to connect the terminal  333  and disconnect the terminal  331 . The movement of the switch  330  will not result in the collapse of arc. Thus, it is possible to use a switch at a trade-off between the performance and the cost. 
         [0027]      FIG. 3   b  illustrates a circuit diagram of another embodiment of the energy conserving device according to the invention. Compared to  FIG. 3   a,  a resistor  350  and a switch  340  in serial are included in the energy conserving module  300  of the energy conserving device  500 . The serial-connected resistor  350  and switch  340  are further connected in parallel to the ballast  310 . At the normal operation (a high illumination degree), the terminals  331  and  332  of switch  330  are connected to each other, and the switch  340  is closed (conductive). Thus, the resistor  350 , like the ballast  310 , is short circuited and inactive. 
         [0028]    When a lower intensity of illumination is needed, the switch  330  will be triggered to connect the terminal  331  and the terminal  333 , while the switch  340  will remain at the closed state for a short period of time, e.g. about 5 seconds. During this period, the power provide by a power module  110  is supplied through the parallel connection of the resistor  350  and ballast  310  to the illumination module  200 . At the end of the period (referred to a “delay period”), the switch  340  will be open (disconnected), and the resistor  350  becomes inactive. The module  200  will work at a reduced voltage, as stated above. It is understood by those skilled in the art that, at the moment of turning the switch  330 , even if the current flowing through the ballast  310  could not be adjusted so quickly that the ballast  310  suffers from an instantaneous disconnection, the illumination module  200  will be power-supplied due to the existence of the parallel circuit consisting of the resistor  350 , the switch  340  and the ballast  310 . In this way, collapse due to the art incident will be further overcome. 
         [0029]    As illustrated in  FIG. 4  which shows another embodiment of the invention, a control module  400  is further incorporated into the energy conserving device  500  so that power module  100 , the control module  400  and energy conserving module  300  connects in serial. The control module  400  comprises a timing circuit  420  for signaling the switch  330  and a power circuit  410  for power-supplying to the timing circuit  420 . 
         [0030]    Preferably, the power circuit  410  is composed of a transformer  411 , a full wave rectifier  412  and the chip controlled regulator  413  connected in serial. 
         [0031]    Preferably, the timing circuit  420  is implemented by utilizing conventional means like a single chip machine or a RC circuitry. 
         [0032]    In an embodiment of the invention, the control module  400  further comprises a power driving circuit such as a power amplifier  430 . Thus, signals produced from the timing circuit  420  will be amplified via a power amplifier  430  and then outputted to the switch  330  and the switch  340  for controlling the operation thereof. 
         [0033]      FIG. 5   a  and  5   b  illustrate a detailed circuit diagram of the energy conserving device as shown in  FIG. 4 . As shown in  FIG. 5   a,  the power module  100  supplies 220V AC current, after passing through the transformer  411 , the output becomes 7.5V AC current. This is fed in to a full wave rectifier  412  and a chip controlled regulator  413  and produces 5V DC current to the single chip machine (SCM), e.g., the SCM89C2051 as shown in  FIG. 5   b.  The SCM89C2051 provides function of a timer. Taken street lights as an example, between 6:00 pm-12:00 am time period, traffic is heavy and road conditions are fairly complicated, which requires a bright illumination. However between 12:00 am-6:00 am, traffic flow is reduced, the road condition improves, and the light intensity can be reduced. Therefore, starting from 6:00 pm, the street lights turn on, and pins  17  and  18  on SCM are high, so as to trigger the switches  330  and  340  (in this embodiment they are relays Q 1  and Q 2  powered by 5V DC from the regulator  413  as shown in  FIG. 5   a ). In this way, the ballast  310  and resistor  350  are short circuited, and the capacitor  320  is disconnected. The street lights work at full capacity under this circuit configuration. When the SCM timer counts to 12:00 am, its 18th pin will change form high to low. The signal passing through a triode S 9012  has been amplified to trigger relay Q 1 , in order to activate the resistor  350 , ballast  310  and capacitor  320 . After delay of 5 seconds SCM will change output of the pin  17  from high to low as well, the signal will again has been amplified to trigger relay Q 2 , thereby disconnecting the resistor  350 . This will result in a reduced voltage level at the two terminals of the module  240 , thus reducing the power output and conserving the energy. 
         [0034]    It is well understood by those skilled in the art, that the control mechanism of this energy conserving device is not limited to the manually-controlling, timing-controlling or SCM-controlling mechanism as mentioned in the above embodiments. Other options like a remote-controlling mechanism may be used according to the practical requirements. 
         [0035]    Sometimes, there is a need for an illumination system to work at multiple modes having various intensities of illumination. As to street lights, since traffic is the heaviest between 6:00 pm-12:00 am, the illumination requires maximum intensity—a full mode. The traffic is light between 12:00 am-4:00 am, so less intensity of illumination is needed—a reduced mode. During 4:00 am-6:00 am, traffic begins to pick up, the illumination intensity should be enhanced above the less intensity but weaker than the full mode-an enhance mode. To this end,  FIG. 6  shows an energy conserving device  500  with capability for multiple operation modes. As illustrated in the  FIG. 6 , the energy conserving device  500  includes serially-connected energy conserving modules  301 ,  302  and  303 , each of which is connected to the control module  400 , respectively. With this configuration, it is possible to achieve multiple outputs, e.g. 4 outputs. In detail, where energy conserving modules  301 ,  302 , and  303  are all inactive, 100% power will be output. The energy conserving modules  301  and  302  are controlled to be in an inactive state while the module  303  works to reduce the energy output by 20%. The energy conserving module  301  is inactive while both the modules  302  and  303  are active, this will reduce power output by 35%. The energy conserving module  301 ,  302 , and  303  all are active, and the power output will be reduced by 50%. 
         [0036]    The energy conserving device according to the present invention can be implemented without changing the circuitry layout of the existing illumination system. This energy conserving device is not only suitable for a new system, but also used as a modification of the existing illumination system. Moreover, this device can not only provide a stable light when needed, but also extend the life of the illumination system. In addition, the device of the invention is cost effective, safe and easy to install. 
         [0037]    It will be understood that the device of the present invention can be integrated into one single component so as to be added to the existing illumination system. For example, the device can be installed at the root of a light pole. 
         [0038]    Furthermore, the energy conserving device of the invention is of a less demand on the switch hence lowering the failure rate thereof. The ballast usually is inactive, even when it is active, the impact on the grid is minor. Also when operated at a reduced voltage level, the switch can atomically set the system back to an appropriate operation mode avoiding a flickering course by power fluctuation. 
         [0039]    The present invention is not limited to the embodiments disclosed herein. Various modifications and variations to the invention will become apparent to those skilled in the art, and such modifications and variations will fall within the scope of the invention as defined in the appended claims.