Abstract:
A light body includes a counting and control unit which counts a switching number of a switch element, and outputs a corresponding enable signal to a driving and light-emitting module to emit light of a selected feature according to the switching number of the switch element. The light body further includes a bridge current rectifying unit in communication with the switch element for converting alternating current received from the power source into direct current. For allowing two or more light bodies to be synchronously controlled, the switching signal indicative of the counted switching number is substantially simultaneously transmitted to the counting and control unit of each of the light bodies without passing through the bridge current rectifying unit.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a lighting device, and more particularly to a lighting device whose functions are selectable according to a switching number of a switch element. 
     BACKGROUND OF THE INVENTION 
     Please refer to  FIG. 1 , which is a circuit block diagram schematically illustrating a lighting device according to prior art. The color temperature of the lighting device  1  is adjustable and controllable. The lighting device  1  includes a switch element  11 , a driving and control device  12  and a light-emitting source  13 . The driving and control device  12  includes a bridge current rectifying unit  121 , a driving circuit  122  and a counting and control unit  123 . The light-emitting source  13  includes a first light emitting diode (LED) unit  131  emitting a light of a first color temperature and a second light emitting diode (LED) unit  132  emitting a light of a second color temperature. The switch element  11 , for example, can be mounted on the wall, while the driving and control device  12  and the light-emitting source  13  can be disposed in a light body  14 . 
     The switch element  11  is coupled to a power source  9 , e.g. mains electricity, and the bridge current rectifying unit  121 . The bridge current rectifying unit  121  converts the alternating current into direct current. The counting and control unit  123  is electrically connected to the bridge current rectifying unit  121 , the driving circuit  122  and the light-emitting source  13 , counting a switching number of the switch element  11 , which is turned on for receiving the direct current from the light-emitting source  13 , and outputting an enable signal accordingly. The driving circuit  122  drives the first LED unit  131  to emit the light of the first color temperature and/or drives the second LED unit  132  to emit the light of the second color temperature. The details of the operational principle are disclosed in Taiwanese Patent Publication No. M392923, and are not to be redundantly described herein. 
     Unfortunately, it is found that the above-described architecture could not be applied to a lighting device with more than one light body due to the synchronous control problem. 
     For explanation in more detail, please refer to  FIG. 2 , which is a circuit block diagram schematically illustrating a light device with two light bodies  14  and  24 . Similar to the lighting device shown in  FIG. 1 , respective light-emitting sources  13  and  23  of the light bodies  14  and  24  emit light of corresponding color temperatures according to the switching number of the switch element  11 . However, since the electronic elements, e.g. capacitors, included in the two lighting bodies for the same functions may still differ in specifications or suffer from manufacturing deviations, the time taken for alternating current to enter the lighting body  14 , be converted into direct current by the bridge current rectifying unit  121  and trigger the counting and control unit  123  to count and the time taken for alternating current to enter the lighting body  24 , be converted into direct current by the bridge current rectifying unit  221  and trigger the counting and control unit  223  may be inconsistent. As a result, the light emission of the light-emitting source  13  of the light body  14  may desynchronize with the light emission of the light-emitting source  23  of the light body  24 . For example, light could be emitted or extinguished at different time points for different lighting bodies. 
     Therefore, there is a need to improve such a light device. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a lighting device under precise synchronization control. 
     In an aspect, the present invention provides lighting device, which comprises:
         a switch element coupled to a power source;   a bridge current rectifying unit in communication with the switch element for converting alternating current received from the power source into direct current;   a driving and light-emitting module in communication with the bridge current rectifying unit; and   a counting and control unit in communication with the switch element and the driving and light-emitting module for counting a switching number of the switch element, and selectively outputting one or both of a first enable signal and a second enable signal to the driving and light-emitting module to execute a corresponding function according to the switching number of the switch element.       

     In an embodiment, the counting and control unit is a programmable microcontroller or a flip-flop. 
     In an embodiment, the counting and control unit starts over the counting of the switching number of the switch element once the switch element is in an off state for a time period longer than a preset time period. 
     In an embodiment, the counting and control unit includes a capacitor for power supply to the counting and control unit during the preset time period. 
     In an embodiment, the driving and light-emitting module includes a driving circuit; a first LED unit coupled to and driven by the driving circuit for emitting a light of a first color temperature in response to the first enable signal; and a second LED unit coupled to and driven by the driving circuit for emitting a light of a second color temperature in response to the second enable signal. 
     Alternatively, the driving and light-emitting module includes a driving circuit; and an LED unit coupled to and driven by the driving circuit for emitting a light of a first luminance in response to the first enable signal, and emitting a light of a second luminance in response to the second enable signal. 
     In an embodiment, the lighting device further comprises a modulating module coupled to the driving and light-emitting module for fine-tuning luminance of the emitted light. In an embodiment, the modulating module includes a variable resistor and the luminance is changed with resistance of the variable resistor. 
     In an embodiment, the modulating module further includes a knob coupled to the variable resistor and rotatable to change the resistance of the variable resistor. 
     In another aspect of the present invention, the lighting device comprises:
         a light-emitting source for providing an illumination light;   a switch element coupled to a power source; and   a driving and control device in communication with the switch element and the light-emitting source for counting a switching number of the switch element, and selectively outputting one or both of a first enable signal and a second enable signal to the driving and light-emitting module to execute a corresponding function according to the switching number of the switch element.       

     In an embodiment, the driving and control device includes a bridge current rectifying unit in communication with the switch element for converting alternating current received from the power source into direct current to be transmitted to the driving and control device. 
     In an embodiment, the driving and control device includes a driving circuit in communication with the light-emitting source; and a counting and control unit in communication with the switch element and the driving circuit for counting the switching number of the switch element, and selectively outputting one or both of the first enable signal and the second enable signal to the driving and light-emitting module to execute the corresponding function according to the switching number of the switch element. 
     In a further aspect, the present invention provides a lighting device, which comprises:
         a bridge current rectifying unit in communication with a mains switch for converting alternating current from a power source into direct current;   a driving and light-emitting module in communication with the bridge current rectifying unit; and   a counting and control unit in communication with the mains switch and the driving and light-emitting module for counting a switching number of the mains switch, and selectively outputting one or both of a first enable signal and a second enable signal to the driving and light-emitting module to execute a corresponding function according to the switching number of the switch element.       

     In an embodiment, the counting and control unit selects to output the first enable signal and/or the second enable signal according to a switching-on number of the mains switch, which is realized by counting an alternating-current receiving number from the power source. 
     In an embodiment, the counting and control unit starts over the counting of the switching-on number of the mains switch once the mains switch is in an off state for a time period longer than a preset time period, and the counting and control unit includes a capacitor for power supply to the counting and control unit during the preset time period. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: 
         FIG. 1  is a circuit block diagram schematically illustrating a lighting device whose color temperature is adjustable and controllable; 
         FIG. 2  is a circuit block diagram schematically illustrating a lighting device with two light bodies; 
         FIG. 3  is a circuit block diagram schematically illustrating a lighting device according to a first embodiment of the present invention; 
         FIG. 4  is a schematic diagram illustrating the use of the lighting device shown in  FIG. 3 ; 
         FIG. 5  is a waveform diagram illustrating the operation of the lighting device shown in  FIG. 3 ; 
         FIG. 6  is a circuit block diagram schematically illustrating a lighting device according to a second embodiment of the present invention; 
         FIG. 7  is a waveform diagram illustrating the operation of the lighting device shown in  FIG. 6 ; 
         FIG. 8  is a circuit block diagram schematically illustrating a lighting device according to a third embodiment of the present invention; and 
         FIG. 9  is a waveform diagram illustrating the operation of the lighting device shown in  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Please refer to  FIG. 3 , which schematically illustrates a lighting device according to a first embodiment of the present invention. The lighting device  3  includes a switch element  31 , which is a power supply switch, a driving and control device  32  and a light-emitting source  33 . The driving and control device  32  is electrically connected to or wirelessly coupled to the switch element  31  and a light-emitting source  33 . When the switch element  31  is switched on, the power source  9  supplies electricity for the driving and control device  32  to drive the light-emitting source  33  so as to provide illumination light. On the other hand, when the switch element  31  is switched off, the power source  9  stops supplying electricity to the driving and control device  32 , and thus the light-emitting source  33  becomes extinguished. In this embodiment, the switch element  31  is controlled with a mains switch  38  standing alone on the wall  8 . By manipulating the mains switch  38 , the switch element  31  can be switched on or off. The driving and control device  32  and the light-emitting source  33  may be, but are not necessarily, two elements disposed inside a light body  34 , as shown in  FIG. 4 . For example, the switch element  31  may be integrated with the light body  34  to form the lighting device  3 . 
     The light-emitting source  33  includes at least a first LED unit  331  emitting light of a first color temperature, a second LED unit  332  emitting light of a second color temperature, a first transistor  333  coupled to the first LED unit  331 , and a second transistor  334  coupled to the second LED unit  332 . In this embodiment, an example of the light of the first color temperature is cold white light having a color temperature of about 6000K, and an example of the light of the second color temperature is warm white light having a color temperature of about 3000K. Please be noted the implementation of the present invention is not limited to the above-mentioned examples. 
     In this embodiment, the driving and control device  32  includes a bridge current rectifying unit  321 , a driving circuit  322  and a counting and control unit  323 , wherein the bridge current rectifying unit  321 , for example, is a programmable microcontroller or a flip-flop, and the driving circuit  322  and the light-emitting source  33 , for example, can be combined as a driving and light-emitting module  35 . Please be noted the implementation of the present invention is not limited to the above-mentioned examples. 
     When the switch element  31  is switched on, the bridge current rectifying unit  321  converts the alternating current from the power source  9  into direct current, and transmits the direct current to the elements of the driving circuit  322 . On the other hand, the counting and control unit  323  directly receives the alternating current from the power source  9 , and outputs one or both of a first enable signal and a second enable signal, depending on the receiving times of the alternating current from the power source  9  corresponding to a switching number of the switch element  31 . The driving circuit  322  then selectively drives the first LED  331  to emit the light of the first color temperature in response to the first enable signal, and selectively drives the second LED  332  to emit the light of the second color temperature in response to the second enable signal. 
     The counting and control unit  323  includes a capacitor  3231 , which provides power for maintaining the work of the counting and control unit  323  for a certain period of time during the off-state of the switch element  31 . The length of the period of time varies with the specification of the capacitor  3231 . In other words, if the switch element  31  keeps off for a time period longer than the time period the capacitor  3231  can supply power, the counting and control unit  323  would finally lose power and become unable to execute the counting task until the switch element  31  is switched on. Then the counting of the switching number of the switch element  31  will start over after the switch element  31  is switched on again. Likewise, the counting of the switching number of the switch element  31  will start over when the switch element  31  is in an off state for a time period longer than a preset one. 
     Please refer to  FIG. 5 , which is a waveform diagram illustrating the operation of the lighting device shown in  FIG. 3 . The first time the switch element  31  is switched on, the counting and control unit  323  receives the alternating current from the power source  9  for the first time, and generates and outputs the first enable signal to turn on the first transistor  333  so as to have only the first LED unit  331  driven to emit light of the first color temperature with 100% power. Afterwards, the switch element  31  is switched off for a specified period of time Td and then switched on again to receive the alternating current from the power source  9  before the counting and control unit  323  runs out of the power supplied by the capacitor  3231 . Meanwhile, the counting and control unit  323  generates and outputs the second enable signal to turn on the second transistor  334  so as to have only the second LED unit  332  driven to emit light of the second color temperature with 100% power. 
     Subsequently, the switch element  31  is switched off again and then switched on again to receive the alternating current from the power source  9  within the power supply time period of the capacitor  3231 . This time, the counting and control unit  323  generates and outputs both the first enable signal and the second enable signal to turn on the first transistor  333  and the second transistor  334 , respectively. With the conduction of both the transistors  333  and  334 , partial current flows through the first LED unit  331  and the second LED unit  332  so as to have the first LED unit  331  driven to emit the light of the first color temperature with 50% power and have the second LED unit  332  driven to emit the light of the second color temperature with 50% power. As a result, the lighting device emits light of a third color temperature, which is synthesized from the light of the first color temperature and the light of the second color temperature. If the light-emitting elements included in the first LED unit  331 , each having a color temperature of 6000K, and the light-emitting elements included in the second LED unit  332 , each having a color temperature of 3000K, are distributed in a well mixed manner, the light of the third color temperature will be normal white light having a color temperature of about 4500K. 
     Please refer to  FIG. 6 , which is a circuit block diagram schematically illustrating a lighting device according to a second embodiment of the present invention. The lighting device  3 ′ in this embodiment is similar to the light device  3  in the first embodiment except that the lighting device  3 ′ further includes a modulating module  36  coupled to the switch element  31  and the driving and control device  32  for modulating luminance of the light-emitting source  33 . 
     In this embodiment, the modulating module  36  includes a variable resistor Rs, capacitors C 1 , C 2  and bidirectional triode thyristors T 1 , T 2 . When the switch element  31  is switched on, the alternating current entering the bridge current rectifying unit  321  from the power source  9  can be modulated by changing the resistance of the variable resistor Rs. In this embodiment, the modulating module  36  is, but not necessarily, manipulated by way of a knob  37  disposed under the mains switch  38 , as shown  FIG. 7 . The knob is coupled to the variable resistor and rotatable to change the resistance of the variable resistor. The bridge current rectifying unit  321  then converts the modulated alternating current into direct current to be transmitted to elements included in the driving circuit  322 . Accordingly, the lighting device  3  provides light with luminance corresponding to the resistance of the variable resistor Rs. 
     Please refer to  FIG. 8 , which is a circuit block diagram schematically illustrating a lighting device according to a third embodiment of the present invention. The common elements included in the lighting device of this embodiment and the lighting device of the first embodiment are not to be redundantly described herein. 
     The lighting device of this embodiment differs from the lighting device of the first embodiment in further comprising another bridge current rectifying unit  421 , another driving circuit  422 , another counting and control unit  423  and another light-emitting source  43 . The bridge current rectifying unit  421 , driving circuit  422 , counting and control unit  423  and light-emitting source  43  work identically to those described in the first embodiment. For example, the counting and control unit  423  is directly coupled to the switch element  31 . In this embodiment, the driving circuit  422  and light-emitting source  43  are elements of another light body  44 , as shown in  FIG. 9 . The respective light-emitting sources  33  and  43  of two light bodies  34  and  44  included in the lighting device of this embodiment are controllable with a single switch. 
     In this embodiment, since the two counting and control units  323  and  423  are both coupled to the switch element  31  and outputs enable signals directly according to the receiving status of the alternating current, the respective light-emitting sources  33  and  43  of two light bodies  34  and  44  emit light synchronously. In other words, by having the two counting and control units  323  and  423  differentially outputs enable signals directly according to the receiving times of the alternating current, the desynchronizing problem encounter by the prior art due to the time variations resulting from inconsistent specifications or manufacturing processes of the elements, e.g. capacitors, included in different light bodies can be avoided. 
     The above three embodiments are just examples given for better understanding the present invention, and can be modified by those skilled in the art according to practical designs and needs. For example, the modulating module  36  used in the second embodiment can also be added into the lighting device in the third embodiment. 
     Furthermore, although each of the lighting devices described in the above three embodiments changes color temperatures of light according to the switching-on number of the switch element, it may be modified to have the color temperatures of light changed according to the switching-off number of the switch element without difficulties based on the disclosure as above. For example, when the switch element  31  is first switched on, the driving circuit  322  drives the light-emitting source  33  to emit light of a first luminance in response to the first enable signal generated by the counting and control unit  323 ; and when the switch element is switched off and then switched on after a specified period of time, the driving circuit  322  drives the light-emitting source  33  to emit light of a second luminance in response to the second enable signal generated by the counting and control unit  323 . In another example, when the switch element is first switched on, the lighting device emits light for illumination, and when the switch element is switched off and then switched on after a specified period of time, the lighting device provides a radio frequency identification (RFID) sensing function. Afterwards, when the switch element is switched off again and then switched on again, the lighting device suspends both the illumination and RFID sensing function. 
     While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.