Abstract:
A bipolar ionization apparatus includes a positive high voltage power supply having an output with at least one positive ion emitting electrode connected thereto and configured to generate positive ions. A negative high voltage power supply has an output with at least one negative ion emitting electrode connected thereto and is configured to generate negative ions. A controller for an ionizer outputs a positive high voltage ionization waveform and a negative high voltage ionization waveform. The controller simultaneously adjusts an amplitude and a duty cycle of each of the waveforms.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 61/003,733, filed on Nov. 19, 2007, entitled “Multiple-Axis Control Method And Apparatus For Ionization Systems,” the entire contents of which is incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     Direct current (DC), pulse, or alternating current (AC) ionization systems having high voltage power supplies and an ionizer typically employ one of two methods to control the balance or net charge of the target area. Amplitude control adjusts the relative amplitudes of positive and negative ionization. This can be achieved through adjustment of either the current or the voltage being applied to the ionizer. 
     Duty cycle control can also be used to control the balance or net charge of the target area. In this type of control, adjustments to the positive and negative ionization cycles are made relative to the time axis. Control is achieved by lengthening or shortening the relative duty cycle of the positive and negative ionization. 
     For the purposes of neutralization and/or balance, adjustments to pulse frequency and waveform shape may also be employed. High voltage pulse frequency may be adjusted up or down for control. Techniques to optimize the exact shape of the output pulses may also be employed. Adjustments to such parameters are made to optimize performance. 
     It is desirable to provide a control method that increases the dynamic range of ionizer control relative to the target area, particularly in applications where the ionizer is close to highly charged objects, such as a moving web or other insulators. It is further desirable to enhance the resolution of either control technique. 
     BRIEF SUMMARY OF THE INVENTION 
     Briefly stated, an embodiment of the present invention comprises a bipolar ionization apparatus that includes a positive high voltage power supply having an output with at least one positive ion emitting electrode connected thereto and configured to generate positive ions. A negative high voltage power supply has an output with at least one negative ion emitting electrode connected thereto and is configured to generate negative ions. A controller for an ionizer outputs a positive high voltage ionization waveform and a negative high voltage ionization waveform. The controller simultaneously adjusts an amplitude and a duty cycle of each of the waveforms. 
     Another embodiment of the present invention comprises a bipolar ionization apparatus that includes a positive high voltage power supply having an output with at least one positive ion emitting electrode connected thereto and configured to generate positive ions. A negative high voltage power supply has an output with at least one negative ion emitting electrode connected thereto and is configured to generate negative ions. A controller is configured to simultaneously adjust an amplitude and a duty cycle of each of the outputs of the positive and negative high voltage power supplies. 
     Still another embodiment of the present invention comprises a bipolar ionization apparatus that includes a positive high voltage power supply having an output with at least one positive ion emitting electrode connected thereto and configured to generate positive ions. A negative high voltage power supply has an output with at least one negative ion emitting electrode connected thereto and is configured to generate negative ions. Each of the outputs of the positive and negative high voltage power supplies has an amplitude and a duty cycle. A controller is configured to selectively adjust at least one of the amplitude and the duty cycle of the outputs of the positive and negative high voltage power supplies. 
     A further embodiment of the present invention comprises a bipolar ionization apparatus that includes a bipolar high voltage power supply having at least one output with at least one ion emitting electrode connected thereto. The bipolar high voltage power supply alternately outputs positive and negative potential. The ion emitting electrode thereby alternately generates positive and negative ions. A controller is configured to simultaneously adjust an amplitude and a duty cycle of the output of the bipolar high voltage power supply. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing summary, as well as the following detailed description of the preferred embodiments of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. 
       In the drawings: 
         FIG. 1  is a schematic block diagram of a bipolar pulse ionization system; 
         FIG. 2A  is a flowchart illustrating an adjustment program for the system of  FIG. 1 ; 
         FIG. 2B  is a flowchart illustrating an alternate adjustment program for the system of  FIG. 1 ; 
         FIG. 3A  is a flowchart illustrating a second adjustment program for the system of  FIG. 1 ; 
         FIG. 3B  is a flowchart illustrating an alternate second adjustment program for the system of  FIG. 1 ; 
         FIG. 4  is a graph showing pulses under amplitude control for the case of equal output; 
         FIG. 5  is a graph showing pulses under duty cycle control for the case of equal output; 
         FIG. 6  is a graph showing pulses under dual axis control for the case of equal output; 
         FIG. 7  is a graph showing pulses under amplitude control for the case of a positive shift; 
         FIG. 8  is a graph showing pulses under duty cycle control for the case of a negative shift; 
         FIG. 9  is a graph showing pulses under dual axis control for the case of a positive shift; 
         FIG. 10  is a graph showing pulses under amplitude control for the case of a negative shift; 
         FIG. 11  is a graph showing pulses under duty cycle control for the case of a negative shift; 
         FIG. 12  is a graph showing pulses under dual axis control for the case of a negative shift; 
         FIG. 13  is a graph illustrating the individual summation of pulse waveforms under amplitude control; 
         FIG. 14  is a graph illustrating the individual summation of pulse waveforms under duty cycle control; 
         FIG. 15  is a graph illustrating the individual summation of pulse waveforms under dual axis control; 
         FIGS. 16A and 16B , taken together, show a table of values used to create the graphs of  FIGS. 4 ,  7 ,  10 , and  13 ; 
         FIGS. 17A and 17B , taken together, show a table of values used to create the graphs of FIGS.  5 , 8 ,  11 , and  14 ; 
         FIGS. 18A and 18B , taken together, show a table of values used to create the graphs of  FIGS. 6 ,  9 ,  12 , and  15 ; 
         FIG. 19  is a graph of HV enable timing signals and HV outputs before application of the multi-axis control in accordance with a preferred embodiment of the present invention; 
         FIG. 20  is a graph of HV enable timing signals and HV outputs after application of the multi-axis control in accordance with a preferred embodiment of the present invention; 
         FIG. 21  is a table of the baseline values of a plurality of modes of the ionization system in accordance with preferred embodiments of the present invention; 
         FIG. 22  is a schematic block diagram of a bipolar ionization system in accordance with a preferred embodiment of the present invention; and 
         FIG. 23  is a schematic block diagram of a bipolar ionization system in accordance with another preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Certain terminology is used herein for convenience only and is not to be taken as a limitation on the present invention. In the drawings, the same reference numbers are employed for designating the same elements throughout the several figures. 
     Dual-axis control combines positive and negative amplitude and duty cycle control and applies these controls to the ionizer simultaneously. The result of this control method is a greatly increased dynamic range of ionizer control relative to the target area. This is particularly useful in application where the ionizer is close to highly charged objects, such as a moving web or other insulators. Another benefit of combining amplitude and duty cycle control is enhanced resolution relative to either technique used alone. Because the controller also has the ability to adjust output pulse frequency and waveform shape, these parameters may also be combined with amplitude and frequency to allow multi-axis control. 
     In a preferred embodiment, dual axis control can be steered using sensors that indicate residual charge on the target. These sensors are located downstream from the ionizer. The ionizer uses the sensor information to simultaneously adjust the amplitude and the duty cycle of the ionizer to eliminate the downstream charge. Referring now to the attached figures, for the purpose of illustrating the invention, there are shown in the drawings, embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. 
       FIG. 1  is a schematic block diagram of a bipolar pulse ionization system. In this preferred embodiment, input is received into a bipolar ionization apparatus  10 . In  FIG. 1 , the input is received by an ionization power supply  12 . The input may be introduced from a plurality of sources including, but not limited to, user input  16 , sensor input  20 , microprocessor input, computer input  18 , or the like. In a preferred embodiment, the input is received by a controller, processor, or other controlling circuitry  14  (for simplicity, hereinafter referred to as “controller  14 ”). Various high voltage generating topologies can be used in the preferred embodiments of the present invention. In particular, various controllers  14 , such as microcontrollers or microprocessors, can be used in the application of the preferred embodiments of the present invention. One suitable controller  14  is the commercially available Z8 Encore microprocessor manufactured by Zilog, Inc. 
     In this preferred embodiment, the controller  14  is coupled to a positive high voltage (HV) power supply  22  and a negative HV power supply  24 , which in turn supply input power to an ionization emitter  26 , shown in  FIG. 1  as an ionizer bar  26 . 
     In this preferred embodiment, the controller  14  is used to provide the frequency response required for the pulse application and desired frequencies. Enable signals  30 ,  31  are provided to the positive and negative HV power supplies  22 ,  24  respectively to set the timing of high voltage pulses. Vprog+ and Vprog− signals  32 ,  33  set the output level. A sensor  34  collects data about neutralization of a target area  36 . As described above, the apparatus  10  is responsive to user input  16 , computer input  18 , sensor input  20 , or other inputs. 
       FIG. 2A  is a flowchart illustrating an adjustment program  250  for an ionization system in accordance with a preferred embodiment of the present invention. Once the configuration of the ionizer  16  is determined (step  252 ), the apparatus  10  is initialized to baseline values (step  254 ), and ion generation begins (step  256 ), the main loop of the adjustment program  250  is entered. The effect of dual axis control in the target area  36  is that a greater range of charge levels can be neutralized than by using either the amplitude or duty cycle controls alone. As shown in  FIG. 2 , the amplitude and duty cycle controls are adjusted simultaneously and applied to the ionizer  16 . The adjustments to the polarity occur simultaneously. By way of example, upon receipt of the sensor, user, or microprocessor input (step  258 ), a determination is made (step  260 ) regarding whether adjustment to the polarity is required. Upon determination that the polarity needs to be adjusted (step  260 ), the adjustments of amplitude and duty control are made simultaneously. If it is determined that the negative polarity (step  262 ) needs to be adjusted to be more positive (step  264 ), the following adjustments are made simultaneously: (1) an increment is made to the Vprog+ (step  266 ), (2) a decrement is made to the Vprog− (step  268 ), and (3) an increment is made to the timing at the cross over counter (step  270 ). Once the variables have been adjusted, check values are compared to a set of limit values (step  280 ). If the check values are within the limit values, the outputs are changed to new values that correspond to the check values (step  282 ). If it is determined that the positive polarity (step  262 ) needs to be adjusted to be more negative (step  272 ), the following adjustments are made simultaneously: (1) an increment is made to the Vprog− (step  274 ), (2) a decrement is made to the Vprog+ (step  276 ), and (3) a decrement is made to the timing at the cross over counter (step  278 ). Once the variables have been adjusted, check values are compared to a set of limit values (step  280 ). If the check values are within the limit values the outputs are changed to new values that correspond to the check values (step  282 ). This process is repeated until the desired polarity is obtained. Control of the balance or the net charge of the target area  36  is achieved by the adjustments to the positive and negative ionization cycles relative to time and by the lengthening and/or shortening of the duty cycles of the positive and negative ionization. Such simultaneous adjustment of the amplitude and duty cycle variables results in a greater effect then the application of either variable individually. 
     Other adjustment variables supported by the controller  14 , such as pulse frequency and waveform shape may optionally be added in the algorithm of  FIG. 2A , such as steps  271 ,  279  shown in  FIG. 2B . Adjustment of these additional variables in combination with the amplitude and the duty cycle provide even greater resolution of ion generation. 
       FIG. 3A  is a flowchart illustrating another adjustment program  350  for an ionization system in accordance with a preferred embodiment of the present invention. Similar to the steps in  FIG. 2 , the ionizer configuration is determined (step  352 ), and the system is initialized to a baseline set of values for the ionizer selected (step  354 ). Ion generation is begun (step  356 ), input from a user, sensor, or microprocessor is received (step  358 ). A determination is made (step  360 ) as to whether adjustment of the polarity of the ionizer is required. In this preferred embodiment, the adjustments are processed as individual steps, for example, if it is determined that the negative polarity (step  362 ) needs to be adjusted to be more positive (step  364 ), one or more of the following steps is processed: (1) an increment to the timing of the cross over counter is made (step  370 ), or (2) an increment to the Vprog+ is made (step  366 ), or (3) a decrement to the Vprog− is made (step  368 ). The adjustments are made in this manner to enhance and increase the resolution. As shown in  FIG. 3 , if the positive polarity (step  362 ) needs to be adjusted to be more negative (step  372 ), one or more of the following steps is processed: (1) a decrement to the timing of the cross over counter is made (step  378 ), or (2) increment to the Vprog− is made (step  374 ), or (3) a decrement to the Vprog+ is made (step  376 ). As shown in  FIG. 3 , the check values after the polarity has been adjusted are compared to a set of limit values (step  380 ). If the check values are within the limit values the outputs are changed to new values that correspond to the check values (step  382 ). This process is repeated until the desired polarity is obtained. The outputs are sent to the ionization power supply  12  as inputs and the process is repeated as necessary. Further resolution is provided by the embodiment shown in  FIG. 3A  as opposed to the simultaneous adjustment technique of  FIG. 2 . 
     Other adjustment variables supported by the controller  14 , such as pulse frequency and waveform shape may optionally be added in the algorithm of  FIG. 3A , such as steps  371 ,  379  shown in  FIG. 3B . Adjustment of these additional variables in combination with the amplitude and the duty cycle provide even greater resolution of ion generation. 
       FIGS. 4 and 5  are graphs that illustrate the individual adjustments of amplitude and duty control for equal outputs.  FIG. 6  is a graph illustrating the dual axis combination of amplitude and duty control for equal outputs.  FIGS. 16A-18B  are tables of the data used to create the graphs shown in  FIGS. 4-6 . Note for the graphs in  FIGS. 4-6  the equal and opposite amplitudes and equal pulse durations. 
       FIG. 7  illustrates the amplitude control shifted positive. Note the increased relative positive output with respect to the negative output, and the equal pulse durations.  FIG. 8  illustrates the duty cycle control shifted positive. Note the increased relative duration of the positive pulse with respect to the negative pulse, and the equal pulse amplitudes.  FIG. 9  illustrates an increased area of relative duration and amplitude of the positive pulse with respect to the negative pulse when the adjustments to amplitude and duty cycles occur simultaneously. The tables found in  FIGS. 16A-18B  include data used to create the graphs shown in  FIGS. 7-9 . 
       FIG. 10  illustrates the amplitude control shifted negative. Note the increased relative negative output with respect to the positive output, and the equal pulse durations.  FIG. 11  illustrates the duty cycle control shifted negative. Note the increased relative duration of the negative pulse with respect to the positive pulse, and the equal pulse amplitudes.  FIG. 12  illustrates an increased area of relative duration and amplitude of the negative pulse with respect to the positive pulse when the adjustments to amplitude and duty cycles occur simultaneously. The tables found in  FIGS. 16A-18B  include data used to create the graphs shown in  FIGS. 10-12 . 
       FIGS. 13 and 14  show graphs illustrating the individual summation of pulse waveforms of amplitude control ( FIG. 13 ), and the summation of pulse waveforms of duty cycle control ( FIG. 14 ).  FIG. 15  shows an increased range of adjustments by the overall combination of positive amplitude resolution and time axis resolution when the adjustments to amplitude and duty cycles occur simultaneously. The tables found in  FIGS. 16A-18B  include data used to create the graphs shown in  FIGS. 13-15 . 
       FIG. 19  is a graph of the HV enable timing signals  1992  and the HV outputs  1993  before application of the multi-axis control to the ionization system in accordance with a preferred embodiment of the present invention. Note the even distribution of the duty cycle and the equal amplitudes of the HV outputs  1993 .  FIG. 20  is a graph of the HV enable timing signals  2092  and the HV outputs  2093  after application of the multi-axis control to the ionization system in accordance with a preferred embodiment of the present invention. Note the 20/80 distribution of the duty cycle and the unequal amplitudes of the HV outputs  2093 . 
       FIG. 21  is a table of the baseline values of a plurality of modes in accordance with the preferred embodiments of the present invention. The table is a range of the upper and lower limits of the output levels for the operating modes of speed, hybrid, and distance with frequency. 
       FIG. 22  is a schematic of a bipolar ionization system in accordance with a preferred embodiment of the present invention. As shown in  FIG. 22 , the enable signals  2230 ,  2231  set the timing of the high voltage pulses and the V prog± signals  2232 ,  2233  set the output level. In the system illustrated, the system is responsive to the input from the user  2216 , sensor  2220 , computer  2218 , or other source. Emitters (not shown) on the ionization bar  2226  are uniquely positive or uniquely negative. 
       FIG. 23  is a schematic of a bipolar ionization system in accordance with another preferred embodiment of the present invention. The system in  FIG. 23  is similar to the system in  FIG. 22 , however, in this embodiment, the emitters are both positive and negative on the ionization bar  2326 , coupled to a bipolar HV power supply  2323 . 
     It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.