Particle flow control

Abstract

A method and a device involving an electric iris diaphragm/shutter are disclosed for controlling particle transfer of electrically charged medication powder particles from a source to a defined target area, of a substrate. Spatial distribution of particles onto the target area is achieved by an electro-dynamic field technique ( 320 ) applied to the distribution and deposition of particles in a dose forming process. An electric iris diaphragm/shutter ( 130 ) is located between a particle generator ( 110 ) and the substrate ( 140 ) such that all particles must pass the iris diaphragm for being transferred to the substrate. By adjusting amplitude and frequency of a superimposed AC potential ( 136 ) charged particles will oscillate in the created AC field such that only small light particles will emerge from the iris diaphragm/shutter for further transfer in the dose forming process.

What is claimed:  
     
         1 . A particle transfer control device for controlling the transfer of electrically charged particles of a medication powder emitted from a particle generator to a defined target area of the substrate member in a dose forming process, wherein 
 an electric iris diaphragm/shutter in a range of 0,07-2 mm in thickness, comprises at least one electrode with at least one aperture with a general measure in a range of 50-5000 μm and has ratio between total thickness and average aperture diameter always being less than 10 and preferably less than 3, whereby the average aperture diameter is defined as the sum of two general measures of the aperture divided by two for the purpose of bringing about electric control of on one hand transfer of charged particles through said at least one aperture and on the other hand distribution of particles onto said defined target area of said substrate member in said dose forming process;    said substrate member having said defined target area is intended for a pre-metered medication dose; and    an electrode behind said defined target area of said substrate member generates a defined electric field when connected to a suitable controlled voltage source with or without a superimposed AC voltage; said defined electric field catching and directing particles emitted from said iris diaphragm/shutter to said target area of said substrate member.    
     
     
         2 . The device according to  claim 1 , wherein said target area of said substrate member is pre-charged such that the pre-charge completely or partly in combination with an electric field from an electrode, when used, behind said defined target area creates a necessary electric field, which catches and directs particles emitted from the iris diaphragm/shutter to the target area of the substrate member.  
     
     
         3 . The device according to  claim 1 , wherin quasi-stationary potentials applied to electrode members force said electric iris diaphragm/shutter to switch a flow of charged particles on or off in said dose forming process.  
     
     
         4 . The device according to  claim 1 , wherein quasi-stationary potentials applied to electrode members force the electric iris diaphragm/shutter to control a mass flow per unit time of charged particles in said dose forming process.  
     
     
         5 . The device according to  claim 1 , wherein quasi-stationary potentials applied to electrode members force the electric iris diaphragm/shutter to control an apparent size of the aperture of the iris diaphragm thereby defining an area of a flow stream of charged particles in said dose forming process.  
     
     
         6 . The device according to  claim 1 , wherein electrical charge is frequently removed from a formed dose and said substrate member by introduction of equalizing charges from a source member such that a repelling electric field from deposited particles is nullified.  
     
     
         7 . The device according to  claim 1 , wherein an ion source is used to make electric contact without physical contact with an electrode on the back side of said substrate member, in order to connect a controlled potential to said electrode thereby creating a necessary electric field emanating from the electrode for transportation of said electrically charged particles to said target area in said dose forming process.