Abstract:
A method of determining a relative condition of an ionizer in an ionization system includes placing the ionization system in a calibration mode, stepping the ionization system through one or more of a range of adjustments, collecting calibration data at each step and storing the calibration data in a memory, placing the ionization system in an operating mode, collecting real-time data regarding an output of the ionization system, comparing the real-time data to the calibration data and determining difference values therebetween, and using the difference values to determine the relative condition of the ionizer.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 61/003,797, filed on Nov. 19, 2007, entitled “Method And Apparatus For Self Calibrating Meter Movement For Ionization Power Supplies,” the entire contents of which are incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     Air ionization is an effective method of creating or eliminating static charges on non-conductive materials and isolated conductors. Air ionizers generate large quantities of positive and negative ions in the surrounding atmosphere that serve as mobile carriers of charge in the air. As ions flow through the air, they are attracted to oppositely charged particles and surfaces. Creation or neutralization of electrostatically charged surfaces can be rapidly achieved through this process. 
     Air ionization may be performed using electrical ionizers, which generate ions in a process known as corona discharge. Electrical ionizers generate air ions by intensifying an electric field around a sharp point until the field overcomes the dielectric strength of the surrounding air. Negative corona discharge occurs when electrons are flowing from the electrode into the surrounding air. Positive corona discharge occurs as a result of the flow of electrons from the air molecules into the electrode. 
     Ionizer devices, such as an electrostatic charging system, an ionization system, or an alternating current (AC) or direct current (DC) charge neutralizing system, take many forms, such as ionizing bars, air ionization blowers, air ionization nozzles, and the like, and are utilized to create or neutralize static electrical charge by emitting positive and negative ions into the workspace or onto the surface of an area. Ionizing bars are typically used in continuous web operations such as paper printing, polymeric sheet material, or plastic bag fabrication. Air ionization blower and nozzles are typically used in workspaces for assembling electronics equipment such as hard disk drives, integrated circuits, and the like, that are sensitive to electrostatic discharge (ESD). Electrostatic charging systems are typically used for pinning together paper products such as magazines or loose leaf paper. 
     Ionizers typically include at least one ionization emitter that is powered by a high voltage power supply. The charge produced by the ionization emitter is proportional to the current flowing through the high voltage supply into the ionization emitter. Over time, an ionizer may accumulate debris. In order to maintain optimal the performance of the ionizer, it is necessary to clean the ionizer in order to remove the debris. As an ionizer accumulates debris, the ionizer&#39;s charge will decrease and, therefore, the current flowing from the voltage supply into the ionizer will also decrease. Conventionally, the current flowing through the voltage supply into the ionizer can be measured by using the return leg of the high voltage transformer or supply, which allows the sum current from the supply to be measured. 
     BRIEF SUMMARY OF THE INVENTION 
     Briefly stated, an embodiment of the present invention comprises a method of determining a relative condition of an ionizer in an ionization system. The method includes placing the ionization system in a calibration mode, stepping the ionization system through one or more of a range of adjustments, collecting calibration data at each step and storing the calibration data in a memory, placing the ionization system in an operating mode, collecting real-time data regarding an output of the ionization system, comparing the real-time data to the calibration data and determining difference values therebetween, and using the difference values to determine the relative condition of the ionizer. 
     A further embodiment of the present invention comprises an apparatus for identifying the relative condition of an ionizer in an ionization system. The apparatus includes a calibrating module and a range module that steps the ionization system through one or more of a range of adjustments. A first collection module collects calibration data at each step and stores the calibration data in a memory. An operating module places the ionization system in an operating mode. A second collection module collects real-time data regarding an output of the ionization system. A comparison module compares the real-time data to the calibration data and determines difference values therebetween based on an operating point of the system, and uses the difference values to determine the relative condition of the ionizer. 
    
    
     
       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 in accordance with a preferred embodiment of the present invention; 
         FIG. 2  is a flowchart associated with the collection of calibration data of an ionization system in accordance with a preferred embodiment of the present invention; 
         FIG. 3  is a flowchart associated with the collection of real time sampling and comparison process with set point adjustments of an ionization system in accordance with preferred embodiments of the present invention; 
         FIG. 4  is a flowchart associated with the collection of real time sampling and comparison process with fixed set points of an ionization system in accordance with preferred embodiments of the present invention; 
         FIG. 5  is an illustration of the meter movement of an ionization system accordance with a preferred embodiment of the present invention; and 
         FIG. 6  is a table of the baseline values and adjustment ranges for an ionization system in accordance with a 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. 
       FIG. 1  is a schematic block diagram of an ionization device  10  according to one embodiment of the present invention. Examples of ionization devices include an electrostatic charging system, an ionization system, and an alternating current (AC) or direct current (DC) charge neutralizing system. The ionization device  10  includes an ionizer power supply  12 , which includes at least one high voltage (HV) power supply  13 . The HV power supply  13  may supply an AC or a DC voltage of about 3 kilo-Volts (kV) to about 60 kV. The ionizer power supply  12  further includes a controller or controller module  14  (for simplicity, hereinafter referred to as “controller  14 ”). In one preferred embodiment, the controller  14  is a microprocessor. In another preferred embodiment, the controller  14  is sensing circuitry. The ionization device  10  further includes at least one ionization emitter  16 , illustrated as the ionizer bar in  FIG. 1 . The emitter  16  is connected to the ionizer power supply  12  by a connector system  18 . The ionizer power supply  12  supplies an input voltage  20  to power the ionization emitter  16 . The input voltage  20  may be described by operating parameters such as voltage level, current level, frequency, maximum voltage, minimum voltage, maximum current, minimum current, or pulse time. The connector system  18  may provide one or more properties of the emitter  16  to the controller  14  in the ionizer power supply  12 , as described in copending U.S. application Ser. No. 11/763,270, entitled “High Voltage Power Supply Connector System,” which is incorporated by reference herein. The controller  14  has detection logic  22  that controls one or more operating parameters of the HV power supply  13  to adjust to the correct settings for the connected emitter  16 . In an alternative embodiment, the detection logic  22  may be included in the connector system  18  so that the connector system  18  directly modifies analog control voltages in the HV power supply  13  based on the properties provided in the connector system  18 . If no emitter or ionizer bar  16  is detected, the HV power supply  13  preferably automatically shuts down the output voltage. 
     DC, Pulse, or AC ionization systems having HV power supplies and an ionizer typically have meter movements or bar graph displays to reflect the relative performance of the system. These types of indicators are important because as the ionizer runs, debris and dirt can collect and impair the ionizer&#39;s ability to neutralize charge. This debris may be either insulative or conductive, which respectively restricts or increases current flow from the ionizer bar. Systems that are currently available are manually adjusted using potentiometers, which can be confusing and or frustrating to the end user. 
     In accordance with one or more preferred embodiments of the present invention, developing an ionization system  10  with a controller  14  allows meter movement to be calibrated at the touch of a button. The controller  14  is preferably designed with adequate dynamic range for all applications and ranges. Fundamentally, the controller  14  preferably includes enough range to accurately collect data on bars of different lengths, where the current flow will be inherently different. To calibrate the meter movement, the controller  14  gathers base line information on the output of the ionization system  10 . The ionizer power supply  12  is cycled through a range of internally stored operating points or steps. Values are recorded as a data point at each operating point or step, and are stored internally. Based on the values recorded, a scaling equation is developed and applied to the meter movement. The meter movement is controlled by the controller  14  using either wireless, digital ports, or an analog output. The range of adjustments may be one or a combination of the following operating modes: speed, hybrid, and distance. 
     In one or more preferred applications of this technique, baseline currents are measured and stored at multiple operating points. The meter movement is adjusted to read full scale at the baseline level. Relative increase and decrease from the baseline currents are shown on the meter as a decrease in level. Relative increases and decreases from the baseline currents are shown as a decrease regardless of whether there is an actual increase due to conductance or a decrease due to insulative debris on the ionizer. They are shown as such, because both types of debris result in the negative effect of impairing the ionizer&#39;s ability to neutralize charge. In a typical application, this assists the user by showing the decrease in the ionizer bar&#39;s efficiency due to either conductive or insulative debris or dirt. Other indicating displays are within the scope of the invention, such as a display that shows a relative level of debris or dirt from a baseline level, or other indicators of efficiency. 
     Referring again to  FIG. 1 , the ionizer power supply  12  receives an input  24  from one or more sources, including user input, sensor data, microprocessor data, or other remote data. The system response to the data from the user, sensor, or microprocessor collects data about the target area of neutralization  26 . In a preferred embodiment an enable signal  28  sets the timing of the high voltage pulses. A Vprogram ± signal  30  sets the output level. In a preferred embodiment, a sensor  32  collects data about the target area of neutralization or the moving web. 
       FIG. 2  is a flowchart illustrating the collection of calibration data. An input is received from a user, microprocessor, or other device coupled to or integral with the ionization system  10 . In the example shown in the flowchart, a calibration button is pushed  224  to enter a calibration mode. Thereafter, a calibration module or sequence  240  is started. During this sequence, a plurality of baseline output currents of the ionizer are measured at one or more points of the high voltage power supply to the ionizer. These output measurements are compiled as the baseline calibration data at each of the points measured. The points measured are set points which are preprogrammed or can be programmed by a user, microprocessor, or other connector system coupled or integral to the ionization system. The set points in memory cover all setting ranges, preferably by uniformly dividing the range and determining the set points. In one embodiment,  250  set points were stored in a memory for compiling the baseline currents data. The baseline currents are measured and stored at each point  248 . 
     Referring to  FIGS. 1 and 2 , an input is received that initiates calibration of the baseline data of the ionization bar selected. In a preferred embodiment, the calibration sequence is started  240 , and the output current of the ionizer at a plurality of points is measured and stored at each point. The points, or set points, are retrievable from memory or from an input source  258 . The set points cover all setting ranges. To cover all setting ranges, the range is uniformly divided and the set points are determined. In a preferred embodiment, a range of 100-300 set points are measured and stored, as set point array  260 . In a more preferred embodiment, 250 set points are measured and stored. The power supply is set to each of the points  262  and data is sampled at each of the points  264 . The data is collected to compile baseline values for the ionizer bar selected. When there is no more set points to implement  246 , and the data is collected at each of the points, the calibration data is stored  248 . In other preferred embodiments, the data is stored throughout the collection process. This process calibrates the power supply to the ionizer selected. In a preferred embodiment, during calibration the process of responding to user, sensor, or microprocessor inputs is suspended. In addition, during this calibration the output values of the current are reset to the baseline values for the ionizer bar selected  245 . The power supply then returns to its normal operation  249 . 
       FIG. 3  is a flowchart associated with a second collection module, which is a collection of real time sampling, and is also associated with a comparison module, or comparison process, with the set point adjustments of an ionization system in accordance with preferred embodiments of the present invention. In  FIG. 3 , there is a set point adjustment in the loop such that stored calibration data is recalled during each loop. The data point that is recalled is the point that is acquired with the power supply closest to the applied set point, or operating point.  FIG. 4  is a flowchart associated with the collection of real time sampling and comparison process with fixed set points such that there is only one stored calibration value  448  that is used, i.e., the one closest to the fixed set point, or operating point  366 . Substantially similar steps in  FIGS. 3 and 4  are represented with the same reference numerals. In accordance with the preferred embodiments of the present invention, the power supply constantly samples the analog to digital readings  364 . The sampling may be constant or intermittent. Based on the set point measured, the calibration data is retrieved  368  for that set point from the baseline values stored for that set point. An absolute percentage difference is calculated  370  from the stored value and the real time reading at the set point. In a preferred embodiment, the retrieved I cal  is the base line calibration measurement at that set point. The retrieved I cal  is assigned a value of 100%. An error from the 100% is calculated. In a preferred embodiment the calculation used to determine the difference is:
 
 I   D   =[I   Cal   −I   rt ]
 
where I D  is the absolute value of base line calibration measurement (I cal ) minus the real-time measurement (I rt ). The percentage difference E % from the baseline calibration is calculated  372  by the following equation:
 
 E  %=100*(1−( I   D   /I   cal )
 
     Upon calculation of the percentage difference, the meter or display of the ionizer power supply is updated  374 . The user interface connected to the ionizer power supply is also updated to display the percentage difference E %. The percentage difference E % is compared against threshold limits for the ionizer bar selected  376 . A clean bar indicator is illuminated when the threshold limit is exceeded  378 . In various preferred embodiments of the present invention, the threshold for the limit wherein the ionizer bar should be cleaned can be configured by the user, a sensor, a microprocessor, or set by software coupled to or located within the ionizer power supply. In a preferred embodiment of the present invention, the current is monitored on the display and the clean bar indicator is illuminated when the current has deviated by an E % of 60% from the calibration value of I cal . 
       FIG. 5  is an illustration of the meter movement of an ionization system.  FIG. 5  illustrates one preferred user interface  500  that displays meter movement detail and the clean bar indicator of the present invention. In the meter movement indicator of  FIG. 5 , an internal percentage scale  550  is displayed on the far right and numbers are assigned to the internal percentage scale which indicate on a simple numerical scale  552  the priority from low to high of the deviations from the baseline calibrations of the ionizer to the real time outputs of the ionizer. As the percentage difference increases, the series of indicator lights  554  illuminate from lowest to highest. When the point percentage difference exceeds a threshold limit, the clean bar light  556  is illuminated. When the ionizer bar is cleaned, the system is reset. In some preferred embodiments, the system can be reset without cleaning of the ionizer bar. 
       FIG. 6  is a table  600  of the baseline values and adjustment ranges for an ionization system. In the preferred embodiments of the present invention, the power supply configures the ionizer bar type that is attached. In a preferred embodiment, the power supply automatically configures the bar type attached using a connector system. In this embodiment, the ionizer bar types have different pin spacings optimized for different operating distances. The power supply runs the bars at different frequencies and output voltages as indicated in the table  600  of  FIG. 6 . Before beginning the calibration, the ionizer bar should be installed in the desired location. During the calibration, the analog to digital readings are gathered. These readings reflect the performance of the bar in the new condition, or base line condition, and account for other factors of the installation. For example, one such factor would be proximity of the bar to grounded metal surfaces. Other factors that are considered and compensated for include the ionizer bar length. Shorter bars have fewer emitter pins and operate at lower currents, while longer bars have more pins and operate at higher currents. During the automatic calibration cycle, this factor is accounted for and, if necessary, corrected in the baseline data. Since the ionizer power supply measures the performance of the ionizer bar when it is installed, the ionizer power supply can use the calibration to scale the meter movement of  FIG. 5 , including user interface or user displays, automatically. There is no need to adjust the potentiometers or otherwise “tweak” the power supply. 
     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.