Device and method for radio frequency drying

Abstract

A radio frequency (RF) drying device is provided. The RF drying device includes a drying chamber including a grounded body enclosing a plurality of N (N≥3) electrodes for generating radio frequency field, and a drum electrically insulated from the plurality of electrodes, and a processor configured to select and activate M (<N) electrodes among the plurality of N electrodes and deactivate one or more remaining (N−M) electrodes periodically and to to select M(<N) electrodes for being activated to generate AC signals and deactivate N−M electrodes for being inactivated not to generate AC signals in an active mode, and RF field is formed inside the drying chamber based on the generated AC signals.

What is claimed is: 
     
         1 . A radio frequency (RF) drying device comprising:
 a drying chamber comprising a grounded body enclosing N (N≥3) electrodes for generating radio frequency field, and a drum electrically insulated from the N electrodes, and   a processor configured to select and activate M (<N) electrodes among the N electrodes and deactivate one or more remaining (N−M) electrodes periodically in an active mode,   wherein a group of M electrodes has a symmetry plane passing through a central axis of the drying chamber which vertically passes through a center of the drying chamber,   wherein the processor is configured to select M electrodes for being activated to generate AC signals and deactivate N-M electrodes for being deactivated not to generate AC signals in the active mode, and to supply AC signals to the activated M electrodes,   wherein RF field is formed inside the drying chamber based on the generated AC signals.   
     
     
         2 . The RF drying device of  claim 1 ,
 wherein the processor is configured to deactivate all the N electrodes in an inactive mode,   and to perform the active mode and the inactive mode by turns.   
     
     
         3 . The RF drying device of  claim 2 , further comprising:
 N matching circuits each of which connected to each of N electrodes, respectively and   N matching sensors each of which connected to each of the N matching circuits, respectively,   wherein each of the N matching circuits comprises at least one inductor and at least one capacitor.   
     
     
         4 . The RF drying device of  claim 3 , further comprising:
 N power amplifiers each of which connected to each of N matching sensors,   wherein the processor is configured to match at a high level exceeding a predetermined matching level between each of the N power amplifiers and each of the N electrodes.   
     
     
         5 . The RF drying device of  claim 4 ,
 wherein the processor is configured to generate N control signals each of which for each of the N matching circuits to adjust parameters of each of the N matching circuits for the matching between each of the N power amplifiers and each of the N electrode.   
     
     
         6 . The RF drying device of  claim 5 ,
 wherein the processor is configured to match load impedance and and output impedance of each of the N electrodes based on each of the N control signals.   
     
     
         7 . The RF drying device of  claim 5 ,
 wherein the processor is configured to monitor values generated from the N matching sensors and to generate the N control signals based on the the values generated from the N matching sensors.   
     
     
         8 . The RF drying device of  claim 2 ,
 wherein the processor is configured to change the selection of M electrodes for being activated among the N electrodes periodically in the active mode.   
     
     
         9 . The RF drying device of  claim 1 ,
 wherein the processor is configured to supply a first AC signal to one or more first electrodes among the M electrodes, lying on one side of the symmetry plane and a second AC signal to one or more second electrodes among the M electrodes, lying on the other side of the symmetry plane, and   wherein the second AC signal is antiphase to the first AC signal.   
     
     
         10 . The RF drying device of  claim 2 ,
 wherein the processor is configured to control power supplied to the N electrodes or switch the active mode to the inactive mode in response to a change of amount of moisture.   
     
     
         11 . The RF drying device of  claim 2 ,
 wherein N is 3 and M is 2, and   wherein the processor is configured to activate any of two electrodes among three electrodes in the active mode including a first active mode, a second active mode and a third active mode and deactivate three electrodes in the inactive mode including a first inactive mode, a second inactive mode and a third inactive mode,   wherein a drying process includes a repetitive process of performing the active mode and the inactive mode.   
     
     
         12 . The RF drying device of  claim 11 ,
 wherein the processor is configured to activate first electrode and second electrode among the three electrodes in the first active mode after the first inactive mode, activate the second electrode and third electrode among the three electrodes in the second active mode after the second inactive mode, and activate the third electrode and the first electrode among the three electrodes in the third active mode after the third inactive mode,   wherein the activated two electrodes receive antiphase signal to an initial signal.   
     
     
         13 . The RF drying device of  claim 12 ,
 wherein the first inactive mode, the first active mode, the second inactive mode, the second active mode, the third inactive mode, and the third active mode are performed sequentially.   
     
     
         14 . The RF drying device of  claims 11 ,
 wherein the processor is configured to replace any one active mode from the drying process with any one inactive mode in response to a matching level being lower than a predetermined matching level, and   wherein the the matching level is a level of matching between each of N power amplifiers and each of the N electrodes.   
     
     
         15 . The RF drying device of  claim 14 , further comprising:
 at least one temperature sensor configured to measure temperature inside the drum,   wherein the processor increase a period of the inactive mode or decrease a period of the active mode in response to the temperature inside the drum exceeding a predetermined temperature threshold.   
     
     
         16 . The RF drying device of  claim 14 , further comprising:
 at least one humidity sensor configured to measure humidity of air inside the drum,   wherein the processor increase a period of the inactive mode or decrease a period of the active mode in response to the humidity of air inside the drum exceeding a predetermined humidity threshold.   
     
     
         17 . The RF drying device of  claim 1 ,
 wherein the each of the N electrodes is of the same shape and evenly spaced around the drum and the central axis passing inside a center of the drying chamber.   
     
     
         18 . The RF drying device of  claim 1 ,
 wherein two adjacent electrodes of the N electrodes have a symmetry plane passing through a center axis of the drying chamber.   
     
     
         19 . A radio frequency (RF) drying device comprising:
 a drying chamber unit having a central axis and including:
 a grounded body, 
 a plurality of N electrodes to generate radio frequency fields, where N≥3, and the plurality of N electrodes are enclosed by the grounded body, and 
 a drying objects housing that is surrounded by the plurality of N electrodes, and is electrically insulated from the plurality of N electrodes; 
   an AC signal configuration block to configure an AC signal for each electrode of the plurality of N electrodes;   a matching unit to match, for each electrode of the plurality of N electrodes, an electrode load impedance with a respective output impedance of the AC signal configuration block; and   a controller,   wherein
 each electrode of the plurality of N electrodes has a same shape, and faces the central axis, 
 the electrodes of the plurality of N electrodes are substantially evenly spaced around the drying objects housing and around the central axis, 
 the electrodes of the plurality of N electrodes are arranged such that any two adjacent electrodes of the plurality of N electrodes have a symmetry plane passing through the central axis, and about which the plurality of N electrodes are symmetrically arranged, and 
 each electrode of the plurality of N electrodes is electrically coupled to the AC signal configuration block via the matching unit, and 
   wherein the controller is configured to:
 control the AC signal configuration block to perform an inactive operation mode in which each electrode of the plurality of N electrodes is in an inactive electrode state, and 
 control the AC signal configuration block to perform a plurality of active operation modes, wherein each active operation mode of the plurality of active operation modes is a mode in which a group of M electrodes of the plurality of N electrodes is in an active electrode state, and remaining electrodes of the plurality of N electrodes are in the inactive electrode state, wherein
 M is a positive even integer, M<N, and 
 the group of M electrodes has a respective symmetry plane passing through the central axis and dividing the electrodes of the group of M electrodes into M/2 symmetrical pairs of electrodes, wherein the electrodes of the group of M electrodes on a first side of the respective symmetry plane are supplied with a first AC signal, and the electrodes of the group of M electrodes on a second side of the respective symmetry plane are supplied with a second AC signal, the first AC signal and the second AC signal being antiphase signals. 
 
   
     
     
         20 . A method of radio frequency (RF) drying, performed by a radio frequency drying device that includes a drying chamber unit having a central axis and including a drying objects housing that is surrounded by, and electrically insulated from, a plurality of N electrodes to generate radio frequency fields, where N≥3, wherein each electrode of the plurality of N electrodes has a same shape, and faces the central axis of the drying chamber unit, the electrodes of the plurality of N electrodes are substantially evenly spaced around the drying objects housing and around the central axis, and the electrodes of the plurality of N electrodes are arranged such that any two adjacent electrodes of the plurality of N electrodes have a symmetry plane passing through the central axis, and about which the plurality of N electrodes are symmetrically arranged, the method comprising:
 placing an object to be dried into the drying objects housing; 
 performing a drying process by alternating a plurality of operation modes including an inactive operation mode and a plurality of active operation modes, wherein
 the inactive operation mode is an operation mode of the plurality of operation modes in which each electrode of the plurality of N electrodes is in an inactive electrode state, 
 each active operation mode of the plurality of active operation modes is a mode in which a group of M electrodes of the plurality of N electrodes is in an active electrode state, and remaining electrodes of the plurality of N electrodes are in the inactive electrode state, wherein 
 M is a positive even integer, M<N, and 
 the group of M electrodes has a respective symmetry plane passing through the central axis and dividing the electrodes of the group of M electrodes into M/2 symmetrical pairs of electrodes, wherein the electrodes of the group of M electrodes on a first side of the respective symmetry plane are supplied with a first AC signal, and the electrodes of the group of M electrodes on a second side of the respective symmetry plane are supplied with a second AC signal, the first AC signal and the second AC signal being antiphase signals; and 
 
 performing impedance matching for each of the electrodes of the group of M electrodes.