Patent Publication Number: US-2013229123-A1

Title: Lighting-dimming device chopping power waveforms for adjusting brightness

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a lighting-dimming device, especially to a lighting-dimming device that chops power waveforms to produce a dimming signal for adjusting brightness. 
     2. Description of Related Art 
     Saving electrical energy is very important for environment protection. Nowadays, people use many electrical products, wherein fluorescent lamps are widely applied in daily life. LED lighting devices gradually substitute for the fluorescent lamps and incandescent lamps for responding to the environment protection. Dimmers are required for adjusting brightness of lighting devices. 
     With reference to  FIG. 9 , a conventional dimmer for adjusting brightness of a lighting device  91  comprises a diode AC switch (DIAC), a triode AC switch (TRIAC), a variable resistor VR 1 , a resistor R 2 , and a capacitor C 1 . A time-delay circuit is formed by the variable resistor VR 1 , the resistor R 1  and the capacitor C 1 . The time-delay circuits determine a conducting time of the DIAC that further controls a conducting time of the TRIAC. When the DIAC and the TRIAC are conducted, the power waveforms of a received sine AC power can be chopped by the DIAC and the TRIAC. 
     The dimmer is connected to a driver  90  and outputs the chopped power to the driver  90 . The driver  90  is connected to the lighting device  91  for driving and adjusting the brightness of the lighting device  91 . The more the sine AC power is chopped, the lower the brightness of the lighting device  91  is. On the other hand, if only little sine AC power is chopped, the driver  90  can output higher energy in average to increase brightness of the lighting device  91 . 
     When the said dimmer is applied to conventional bulbs or LED lighting devices, the power factor is decreased because the received power in each duty of time has been chopped. How to maintain the power factor without significantly changing an original wiring system is an essential issue. 
     Moreover, the conventional dimmer is an analog-based device using a variable resistor for dimming. The dimmer cannot be applied to an advanced user interface or for a long distance dimming. For an illuminating system with multiple lighting devices, the dimmer is unable to adjust each of the lighting devices separately. 
     SUMMARY OF THE INVENTION 
     An objective of the present invention is to provide a lighting-dimming device capable of maintaining a high power factor. 
     To achieve the above-mentioned objective, the lighting-dimming device comprises: 
     a dimming module comprising:
         a converter outputting a voltage signal in response to a dimming and addressing command;   a quantizer receiving the voltage signal output from the converter and outputting a brightness and address signal in response to the voltage signal;   an encoder producing an encoded signal corresponding to the brightness and address signal; and   a triode AC switch controlled by the encoded signal to turn on and off for chopping a power, wherein the power is chopped only during a part of cycles to represent the brightness and address signal; and       

     at least one light module receiving the chopped power, connected to the dimming module and comprising:
         a decoder generating a combination signal based on the chopped power;   a driver generating a driving signal based on the combination signal; and       

     an illuminating unit connected to the driver and controlled by the driving signal to produce light with required brightness. 
     The dimming module receives an input power and a brightness and address command from a user interface input by a user. The encoder of the dimming module outputs an encoded signal corresponding to the brightness and address command to change a conducting time of the TRIAC and thus to produce a chopped power. 
     When the decoder of the at least one light module receives the chopped power, a combination signal is generated based on the chopped power and outputted to the driver for driving the illuminating unit to generate light with required brightness corresponding to the brightness and address command. In the present invention, only the power during a part of multiple continuous cycles is chopped. Therefore, the chopped power still remains in the original state substantially without obvious deformations. The power factor is accordingly kept high. Further, the user can easily and conveniently install or replace the lighting-dimming device of the present invention without changing an original wiring system in a house. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of the present invention; 
         FIG. 2  is a block diagram of a dimming module of the present invention; 
         FIG. 3  is a block diagram of a light module of the present invention; 
         FIG. 4A  is a waveform chart of a rectified full-wave power of the present invention; 
         FIG. 4B  is a waveform chart of a first embodiment of an encoded signal output from the encoder of the present invention; 
         FIG. 4C  is a waveform chart of a chopped power corresponding to  FIG. 4B  of the present invention; 
         FIG. 4D  is a schematic view of a combination signal of the present invention; 
         FIG. 5  is a table showing different data codes that represent different levels of brightness of the present invention; 
         FIG. 6  is a block diagram of multiple dimming modules connected with multiple light modules of the present invention; 
         FIG. 7A  is a waveform chart of a full-wave power; 
         FIG. 7B  is a waveform chart of a second embodiment of an encoded signal output from the encoder of the present invention; 
         FIG. 7C  is a waveform chart of a chopped power corresponding to  FIG. 7B  of the present invention; 
         FIG. 8  is a waveform chart of a third embodiment of chopped power of the present invention; and 
         FIG. 9  is a block diagram of a conventional dimming circuit. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     With reference to  FIG. 1 , the lighting-dimming device comprises a dimming module  10  and at least one light module  20  such as an LED lighting device that is installed on ceilings and connected to the dimming module  10  in series. The dimming module  10  in this embodiment is mounted in a switch panel of a wall-mounted switch. 
     With reference to  FIG. 2 , the dimming module  10  comprises a first rectifier  11 , a voltage regulator  12 , a converter  13 , a quantizer  14 , a first filter  15 , an encoder  16 , a signal generator  17 , a triode AC switch (TRIAC)  18  and a zero-voltage detector  19 . 
     The first rectifier  11  has two input terminals connected to two lines of a wall-mounted switch to receive a sine AC power. The first rectifier  11  outputs a rectified full-wave power as shown in  FIG. 4A  to the voltage regulator  12 . The voltage regulator  12  outputs a stabilized operating voltage. 
     The converter  13  outputs a voltage signal to the quantizer  14  in response to a dimming and addressing command. In this embodiment, the converter  13  outputs a voltage signal to the quantizer  14  under the control of two variable resistors VR 1  and VR 2 . The two variable resistors VR 1  and VR 2  are configured in association with the wall-mounted switch, so a user can indirectly adjust the variable resistors VR 1  and VR 2  via the wall-mounted switch to control the voltage signal output from the converter  13 . In other words, the dimming and addressing command is implemented by adjusting the variable resistors VR 1  and VR 2  so as to control the converter  13  to output a required voltage signal. 
     The quantizer  14  outputs a brightness and address signal corresponding to the voltage signal to the first filter  15 . The first filter  15  filters noise of the brightness and address signal and then outputs the brightness and address signal to the encoder  16 . Upon reception of the brightness and address signal, the encoder  16  refers to a built-in database to produce a corresponding encoded signal and then outputs the encoded signal to the signal generator  17 . The signal generator  17  outputs a square signal to the TRIAC  18  to control a conducting time of the TRIAC  18 . With the foregoing circuit operations, a chopped power corresponding to the encoding signal can be generated. 
     With reference to  FIG. 3 , the light module  20  in the first embodiment includes a second rectifier  21 , an analog-digital converter  22 , a second filter  23 , a decoder  24 , a pulse width modulator  25 , a driver  26  and an illuminating unit  27  connected in series, and further includes a digital phase-lock unit  28  connected between the analog-digital converter  22  and the decoder  24 . 
     When the second rectifier  21  receives the chopped power and rectifies the chopped power to a full-wave chopped power, the analog-digital converter  22  converts the chopped power to a digital signal. After noise of the digital signal is filtered by the second filter  23 , the digital signal is outputted to the decoder  24  for decoding. The decoder  24  decodes the digital signal to a combination signal including an initial code, an address code, a data code and a parity-check code as shown in  FIG. 4D . The combination signal is represented by “1” and “0” respectively corresponding to a high potential and a low potential of the chopped power. The combination signal is outputted to the pulse width modulator  25 . The pulse width modulator  25  receives the combination signal and accordingly generates a pulse width modulation (PWM) signal output to the driver  26 . Therefore, the driver  26  outputs a driving signal to control the illuminating unit  27  to generate required brightness. The digital phase-lock unit  28  receives the digital signal from the analog-digital converter  22  for the purpose of synchronization. 
     With reference to  FIG. 2 , an output terminal of the first rectifier  11  is connected to the zero-voltage detector  19 . The function of the zero-voltage detector  19  is to ensure that encoded signal will be synchronized with the rectified full-wave signal. The voltage regulator  12  also provides the operating power required by the dimming module  10 . The user can control an operating interface, such as the variable resistors VR 1 /VR 2  or other interfaces, of the converter  13  to generate an adjusting signal to the quantizer  14 . 
     When the user adjusts the converter  13  of the dimming module  10 , for example via adjusting the variable resistors VR 1 /VR 2  to produce a required voltage, the quantizer  14  accordingly generates the brightness and address signal. The encoder  16  generates the encoded signal corresponding to the brightness and address signal as shown in  FIG. 4B  by referring to the built-in database. The encoder  16  outputs the encoded signal to the TRIAC  18 . With reference to  FIG. 4C , by turning on and off the TRIAC  18 , the chopped power is produced. When the light module  20  receives the chopped power, the decoder  24  based on the chopped power produces the combination signal output to the pulse width modulator  25 . Then the pulse width modulator  25  outputs the PWM signal to the driver  26 . The driver  26  outputs the driving signal to control the illuminating unit  27  to generate required brightness. 
     With reference to  FIG. 5 , the brightness of the illuminating unit  27  is decided by the data code. In this embodiment, the lighting-dimming device can generate 32 levels of brightness. With reference to  FIG. 6 , multiple dimming modules  10  in parallel are connected to multiple light modules  20  in parallel. The quantizers  14  of these dimming modules  10  can be designated with different address codes as their ID codes respectively. The light modules  20  having a matched ID will be controlled by a corresponding dimming module  10 . In another aspect, a single dimming module  10  can simultaneously control multiple light modules  20  which have the same ID corresponding to the dimming module  10 . If there are multiple dimming modules  10 , different groups of the light modules  20  can be respectively and correspondingly controlled by the multiple dimming modules  10 . 
     In the present invention, only the AC power in a part of cycles has been chopped. The AC power can remain in the original state substantially without significant deformations. Therefore, in comparison to the conventional light dimming approach, the power factor in accordance with the present invention will be kept high. The lighting-dimming device of the present invention can be applied to dim the illuminating devices in the building without changing the original wiring system. 
     With reference to  FIGS. 7A to 7C , the present invention provides a second embodiment of the chopped power.  FIG. 7A  shows a positive sine power.  FIG. 7B  is a driving signal output by the encoder  16  to control the TRIAC  18 . By turning on and off the TRIAC  18 , the positive sine power is adjusted as shown in  FIG. 7C , wherein the power is chopped during a part of cycles. The conducting time of the TRIAC  18  determines the waveforms of the chopped power. The decoder  24  identifies the cycle with complete power as “1” and identifies the cycle with the chopped power as “0”. The chopped portion in each cycle of the second embodiment is less than that of the first embodiment. Therefore, the power factor of the second embodiment is higher than the first embodiment. 
       FIG. 8  is a third embodiment of the present invention. The power can be chopped in accordance with a required phase angle. The different phase angles can be interpreted as different data codes. For example, when a half portion of a waveform in a cycle is chopped, the chopped cycle will be interpreted to represent 50% of full brightness. When one-eighth portion of a waveform in a cycle is chopped, the chopped cycle will be interpreted to represent seven-eighths of full brightness. This embodiment chops only a portion of a single cycle. Therefore, energy loss of this embodiment is much lower than those of the first embodiment and second embodiment to maintain a higher power factor.