Abstract:
An air cleaner is provided, comprising a control unit, an inverter, a negative ion generator, and an ozone gas generator. The control unit generates a control signal. The inverter coupled to the control unit generates a voltage according to the control signal. The negative ion generator coupled to the inverter receives the voltage to generate a negative ion. The ozone gas generator coupled to the inverter receives the voltage to generate an ozone gas. The negative ion generator and the ozone generator are both activated when the voltage is larger than a first voltage level, and the negative ion generator is activated and the ozone gas generator is deactivated when the voltage is less than the first voltage level and larger than a second voltage level.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to an air cleaner, and more particularly to air cleaners where a negative ion generator and an ozone gas generator share a common inverter. 
         [0003]    2. Description of the Related Art 
         [0004]    Due to consistent pollution in modern cities, more and more illnesses related to poor air quality occur while in indoor settings. Thus, air cleaners are used to filter out harmful substances and provide clean indoor air. 
         [0005]    Conventional air cleaners can generate negative ions and ozone gas. The negative ions can absorb air particles (e.g. pollen, dust, cigarette smoke) and then fall to the ground. An ozone molecule composed of three oxygen atoms is a strong oxidant and can oxidize various odorous gases to eliminate unpleasant odors, and the ozone gas converts to oxygen gas after the chemical reaction. Furthermore, a high concentration of the ozone gas can be used as a bactericide; however, the ozone gas is a strong stimulus to the respiratory tract of human beings and can cause difficulty of breathing, chest pains, coughing, or throat pains. Consequently, the air cleaner is required to generate the negative ions and deactivate the generation of the ozone gas when someone is inside the enclosed area encompassing the air cleaner. 
         [0006]      FIG. 1  is architecture of a conventional air cleaner  100 . The air cleaner  100  comprises a control unit  102  used to control a negative ion generator  104  and an ozone gas generator  106 . The negative ion generator  104  is composed of a boost circuit and a point discharge electrode. The boost circuit can convert an alternative current (AC) voltage to an extremely high negative voltage and then output it to the point discharge electrode. The point discharge electrode is an open loop circuit capable of ionizing surrounding air as negative ions. The ozone gas generator  106  is composed of two electrodes, and a high direct current (DC) voltage difference applied to the electrodes can induce a current to flow between the two electrodes. An arc is generated to convert the oxygen gas of surrounding air to the ozone gas when the current rises to a predetermined level. The electrodes of the ozone gas generator  106 , however, cannot receive the high DC voltage for a long period of time, so an AC voltage is needed to intermittently drive the electrodes to generate the ozone gas. 
         [0007]    Accordingly, both the negative ion generator  104  and the ozone gas generator  106  are required to be driven by the AC voltage. Because the ozone gas is harmful for human beings, the ozone gas must be generated when no one is inside the enclosed area of the air cleaner. The negative ions, however, are required to be continuously generated when the air cleaner is activated, so the negative ion generator  104  and the ozone gas generator  106  must be driven separately. Referring to  FIG. 1 , the negative ion generator  104  is driven by an inverter  108 , while the ozone gas generator  106  is driven by an inverter  110 . The inverters  108  and  110  can be respectively controlled by the control unit  102  to provide AC voltages of different amplitudes. When someone is inside the enclosed area of the air cleaner, the control unit  102  can deactivate the inverter  110  to stop the ozone gas generator  106  from generating the ozone gas. Meanwhile, the control unit  102  still activates the inverter  108  to output the AC voltage to the negative ion generator  104  to continue to generate the negative ions. 
         [0008]    The use of the two inverters not only results in high production costs but also requires large circuit area, so that it is difficult to reduce the size of the air cleaner. Therefore, an unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    Certain aspects commensurate in scope with the originally claimed invention are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain forms the invention might take and that these aspects are not intended to limit the scope of the invention. Indeed, the invention may encompass a variety of aspects that may not be set forth below. 
         [0010]    The invention provides an air cleaner capable of providing an inverter shared by a negative ion generator and an ozone gas generator in a Burst Mode. The air cleaner comprises a control unit, an inverter, a negative ion generator, and an ozone gas generator. The control unit generates a control signal. The inverter coupled to the control unit generates a voltage according to the control signal. The negative ion generator coupled to the inverter receives the voltage to generate a negative ion. The ozone gas generator coupled to the inverter receives the voltage to generate an ozone gas. The negative ion generator and the ozone generator are both activated when the voltage is larger than a first voltage level, and the negative ion generator is activated and the ozone gas generator is deactivated when the voltage is less than the first voltage level and larger than a second voltage level. 
         [0011]    The invention provides an air cleaner capable of providing an inverter shared by a negative ion generator and an ozone gas generator in a DC Mode. The air cleaner comprises a control unit, an inverter, a negative ion generator, an ozone gas generator, and a control circuit. The control unit generates a switch signal. The inverter coupled to the control unit receives a feedback signal with a predetermined voltage level to generate a voltage. The negative ion generator coupled to the inverter receives the voltage to generate a negative ion. The ozone gas generator coupled to the inverter receives the voltage to induce a current for generating an ozone gas. The control circuit coupled to the control unit, the inverter, and the ozone gas generator, receives the switch signal to generate the feedback signal. The feedback signal is increased to reduce the voltage when the negative ion generator is to be activated and the ozone gas generator is to be deactivated, thereby enabling the feedback signal to return to the predetermined voltage level. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
           [0013]      FIG. 1  is architecture of a conventional air cleaner  100 ; 
           [0014]      FIG. 2  is a block diagram of an air cleaner  200  according to an embodiment of the invention; 
           [0015]      FIG. 3  is the circuitry of the air cleaner  200 ; 
           [0016]      FIG. 4  is a block diagram of an air cleaner  400  according to another embodiment of the invention; and 
           [0017]      FIG. 5  is the circuitry of the air cleaner  400 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]      FIG. 2  is a block diagram of an air cleaner  200  according to an embodiment of the invention. The air cleaner  200  uses a control signal to control the generation of the ozone gas in a Burst Mode. A control unit  202  outputs a control signal  210  to control the generation of the ozone gas, and the control signal  210  is a pulse width modulation (PWM) signal. 
         [0019]    The air cleaner  200  comprises a control unit  202 , a negative ion generator  204 , an ozone gas generator  206 , and an inverter  208 . The inverter  208  is coupled to the control unit  202 , and can output an AC voltage  212  according to the control signal  210 . The negative ion generator  204  is coupled to the inverter  208 , and can receive the AC voltage  212  to generate negative ions. The ozone gas generator  206  is also coupled to the inverter  208 , and can generate a current according to the AC voltage  212  to induce an arc to generate the ozone gas. It is noted that the current generated by the ozone gas generator  206  can be converted to a feedback signal  214  and then input into the inverter  208 . 
         [0020]    Generally, the threshold voltage enabling the ozone gas generator  206  to generate the ozone gas is higher than the threshold voltage enabling the negative ion generator  204  to generate the negative ions. Accordingly, when someone enters an enclosed area encompassing the air cleaner and the ozone gas generator  206  is required to be deactivated, the control unit  202  can output a higher than a predetermined duty cycle control signal  210  to the inverter  208 , and then the inverter  208  can output the AC voltage  212  with an amplitude lower than the threshold voltage of the generation of the ozone gas and higher than the threshold of the generation of the negative ions. Therefore, the control unit  208  can individually deactivate the ozone gas generator  206  while still activating the negative ion generator  204 . An advantage of the air cleaner  200  is that only one inverter is required to provide the AC voltage to the negative ion generator and the ozone gas generator. 
         [0021]      FIG. 3  is the circuitry of the air cleaner  200 . The inverter  208  comprises a pulse width modulator  216 , a switch device  218 , and a transformer  220 . The pulse width modulator  216  can output a driving signal (e.g. the output of output ports OUT 1  and OUT 2 ) to drive the switch device  218  according to the control signal  210  and the feedback signal  214 . The driving signals output by the output ports OUT 1  and OUT 2  are PWM signals and inverted with each other. The switch device  218  is coupled to the pulse width modulator  216  and a supply voltage Vc, and can output a PWM signal  219  according to the driving signal. The switch device  218  in the embodiment can be a half-bridge switch, a full-bridge switch, or other topologies known in the art. 
         [0022]    The transformer  220  has a primary side coupled to the switch device  218  and a secondary side coupled to the negative ion generator  204  and the ozone gas generator  206 . The transformer  220  can convert the PWM signal  219  to the AC voltage  212  with a high amplitude, and the amplitude of the AC voltage  212  can be increased with the increase of the duty cycle of the PWM signal  219 . 
         [0023]    The negative ion generator  204  is coupled to the transformer  220 , and comprises a boost circuit capable of increasing the voltage  212  to an extremely high negative voltage to generate the negative ions. The ozone gas generator  206  is also coupled to the transformer  220 , and comprises two electrodes used to generate a current  213  according to the AC voltage  212 . The ozone generator  206  starts to generate the ozone gas when the current  213  is larger than a threshold value (i.e. the voltage  212  is larger than a voltage level). The current  213  can be converted to the feedback signal  214  by a resistor  222 . The pulse width modulator  216  can output the driving signal according to the control signal  210  and the feedback signal  214 . 
         [0024]    In the embodiment of  FIG. 3 , the pulse width modulator is controlled by negative feedback, so for stable operation, a predetermined voltage level requires the sum of the PWM signal  210  and the feedback signal  214 . When the sum is increased, the inverter  208  can reduce the AC voltage  212  to stop the ozone gas generator  206  from generating the ozone gas and reduce the feedback signal  214  to force the sum to return to the predetermined voltage level. On the contrary, when the sum is decreased, the inverter  208  can increase the AC voltage  212  to enable generation of the ozone gas and increase the feedback signal  214  to force the AC voltage  212  to return to the predetermined voltage level. It is noted that the frequency of the PWM signal  219  is higher than that of the control signal  210 . In one embodiment, the control unit  202  can be a micro control unit (MCU), and the control unit  202  can output an ON/OFF signal  211  to the pulse width modulator  216  to activate or deactivate the negative ion generator  204  and the ozone gas generator  206 . 
         [0025]      FIG. 4  is another embodiment of block diagram of air cleaner  400 . In the embodiment, the air cleaner  400  controls the generation of the ozone gas in a DC mode. The air cleaner  400  comprises a control unit  402 , a negative ion generator  404 , an ozone gas generator  406 , an inverter  408 , and a control circuit  424 . The inverter  408  is coupled to the control unit  402  and the control circuit  424 , and can generate an AC voltage  412  according to a DC voltage  410  output by the control unit  402  and a feedback signal  414  output by the control circuit  424 . The DC voltage  410  controls the concentration of the ozone gas generated by the ozone gas generator  406 . The concentration of the ozone gas decreases with the increase of the DC voltage  410 . The negative ion generator  404  is coupled to the inverter  408 , and can receive the AC voltage  412  to generate the negative ions. The ozone gas generator  406  is also coupled to the inverter  408 , and can receive the AC voltage  412  to generate the ozone gas. The current generated by the ozone gas generator  406  can be converted to the feedback signal  414  by the control circuit  424  and then output to the inverter  408 . 
         [0026]    The sum of the feedback signal  414  and the DC voltage  410  has a predetermined voltage level. The feedback signal  414  is unchanged when the DC voltage  410  is fixed. For example, when someone enters an enclosed area encompassing the air cleaner and the ozone gas generator  406  is required to be deactivated, the control unit  402  can output a switch signal  415  to the control circuit  424  to increase the feedback signal  414 , thereby increasing the sum of the feedback signal  414  and the DC voltage  410 . Meanwhile, the inverter  408  reduces the AC voltage  412  to reduce the feedback signal  414 , thereby forcing the feedback signal  414  to return to its original voltage level. The amount of decrease of the AC voltage  412  can be controlled by the internal circuit of the control circuit  424 , and therefore the AC voltage  412  generated by the inverter  408  can be controlled between the threshold voltage of the generation of the ozone gas and the threshold voltage of the generation of the negative ions. Consequently, the negative ion generator  404  can be activated while the ozone gas generator  406  is deactivated, and further share the same inverter  408  as the ozone gas generator  406 . 
         [0027]      FIG. 5  is the circuitry of the air cleaner  400 . The inverter  408  comprises a pulse width modulator  416 , a switch device  418 , and a transformer  420 . The pulse width modulator  416  can output a driving signal according to the sum of the DC voltage  410  and the feedback signal  414 . The switch device  418  can output a PWM signal  419  according to the driving signal. The primary side of the transformer  420  is coupled to the switch device  418 , and the secondary side of the transformer  420  is coupled to the negative ion generator  404  and the ozone gas generator  406 . The transformer  420  can convert the PWM signal  419  to the AC voltage  412  with high amplitude. The amplitude of the AC voltage  412  is proportional to the duty cycle of the PWM signal  419 . 
         [0028]    The function of the negative ion generator  404  and the ozone gas generator  406  are respectively the same as the negative ion generator  204  and the ozone gas generator  206 , thus they will not be described hereafter for brevity. The control circuit  424  comprises a switch  421  and a resistor  423 . The switch  421  can be a transistor. 
         [0029]    When no one is inside the enclosed area encompassing the air cleaner and the ozone gas generator  406  is required to be activated, the control unit  402  can output the switch signal  415  to turn on the switch  421 , and the feedback signal  414  can be the resistance of a parallel connection of the resistors  422  and  423  multiplied by the current  413 . On the contrary, when someone enters the enclosed area encompassing the air cleaner and the ozone gas generator  406  is required to be deactivated, the control unit  402  can output the switch signal  415  to turn off the switch  421 , and the feedback signal  414  can be the resistance of the resistor  422  multiplied by the current  413 . 
         [0030]    During the process when the ozone gas  406  is deactivated, the feedback signal  414  is increased when the switch  421  is turned on, because the current  413  does not change immediately at the moment the switch  421  is turned on and the resistance of the resistor  422  is larger than the resistance of the parallel connection of the resistors  422  and  423 . Therefore, the inverter  408  can reduce the AC voltage  412  to reduce the current  413 , thereby forcing the feedback signal  414  to return to its original voltage level and reduce the current of the ozone gas generator  406  to deactivate the generation of the ozone gas. It is noted that the voltage supplied to the ozone gas generator and the negative ion generator can be reduced by controlling the resistance of the feedback resistors. Accordingly, the ozone gas generator and the negative ion generator can share the same inverter. In one embodiment, the control unit  402  can be an MCU outputting an ON/OFF signal  411  to the pulse width modulator  416  to activate or deactivate the negative ion generator  404  and the ozone gas generator  406  at the same time. 
         [0031]    While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.