Flow metering for dispense monitoring and control

Abstract

Methods and systems of accurately dispensing a viscous fluid onto a substrate. In an embodiment, a method includes using an electronic flow meter device to produce electrical flow meter output signals and performing a responsive control function in a closed loop manner by adjusting at least one dispensing parameter to correct for a difference between an output data set and a reference data set. In another embodiment, a system includes a control operatively coupled to a gas flow meter device and to a weigh scale allowing for a density of an amount of viscous material to be determined. In another embodiment, a method includes using a control coupled to both a gas flow meter device and a weigh scale and performing a responsive control function in a closed loop manner by adjusting at least one dispensing parameter using gas flow meter output signals and weigh scale output signals.

What is claimed is: 
     
         1 . A method of controlling a non-contact jetting dispensing system to accurately dispense a viscous fluid onto a substrate, the method comprising:
 directing the viscous fluid from a viscous fluid supply into a non-contact jetting dispenser having an inlet and an outlet;   discharging the viscous fluid through the outlet of the non-contact jetting dispenser, the non-contact jetting dispenser being operable to start and stop flow of the viscous fluid through the outlet onto the substrate;   using an electronic flow meter device operatively coupled to the viscous fluid supply or the outlet of the non-contact jetting dispenser to produce electrical flow meter output signals corresponding to the flow rate of the viscous fluid through a flow path between the viscous fluid supply and the outlet of the non-contact jetting dispenser, the electrical flow meter output signals forming an output data set;   comparing the output data set to a reference data set stored in a controller; and   performing a responsive control function in a closed loop manner by adjusting at least one dispensing parameter to correct for a difference between the output data set and the reference data set.   
     
     
         2 . The method of  claim 1 , wherein performing the responsive control function further comprises adjusting the flow rate of the viscous fluid flowing through and being dispensed through the outlet of the non-contact jetting dispenser. 
     
     
         3 . The method of  claim 2 , wherein adjusting the flow rate further comprises adjusting the viscosity of the viscous fluid. 
     
     
         4 . The method of  claim 1 , wherein performing the responsive control function further comprises adjusting the dispensing time. 
     
     
         5 . The method of  claim 1 , wherein performing the responsive control function further comprises adjusting the frequency at which viscous fluid is dispensed through the outlet onto the substrate. 
     
     
         6 . The method of  claim 1 , wherein:
 the viscous fluid supply further comprises a pressurized supply using pressurized air flowing through a pneumatic input of the viscous fluid supply,   the electronic flow meter device further is operatively coupled to the pneumatic input to produce electrical flow meter output signals corresponding to the flow rate of the pressurized air flowing through the pneumatic input, and   adjusting the at least one dispensing parameter further comprises adjusting the pressure of the pressurized supply.   
     
     
         7 . The method of  claim 1 , wherein:
 discharging the viscous fluid through the outlet further comprises discharging the viscous fluid through the outlet during relative motion between the non-contact jetting dispenser and the substrate; and   performing the responsive control function further comprises adjusting the speed of the relative motion between the non-contact jetting dispenser and the substrate.   
     
     
         8 . The method of  claim 1 , wherein:
 comparing the output data set to the reference data set further comprises using the output data set to determine a speed of relative motion between the non-contact jetting dispenser and the substrate which results in a target amount of viscous fluid being discharged onto the substrate, wherein determining the speed of relative motion comprises:
 determining amount of viscous fluid in the form of a total number of dots required to substantially equal the target amount by determining an average per dot volume of the output data set; 
 determining a distance between each of the total number of dots required to distribute the dots; and 
 determining a rate at which the total number of dots is to be dispensed from the non-contact jetting dispenser; and 
 using the rate at which the total number of dots is to be dispensed and the distance between each of the dots in the total number of dots; and 
   performing the responsive control function further comprises adjusting the speed of the relative motion between the non-contact jetting dispenser and the substrate to discharge the target amount of viscous fluid onto the substrate.   
     
     
         9 . The method of  claim 1 , wherein comparing the output data set to the reference data set stored in the controller further comprises integrating the output data set to determine a volume of the output data set. 
     
     
         10 . The method of  claim 9 , wherein:
 comparing the output data set to the reference data set further comprises comparing the volume of the output data set to a reference volume of the reference data set; and   performing the responsive control function further comprises performing the responsive control function in the closed loop manner by adjusting the at least one dispensing parameter to correct for the difference between the volume of the output data set and the reference volume of the reference data set.   
     
     
         11 . The method of  claim 1 , wherein performing the responsive control function further comprises detecting an air bubble in the viscous fluid flowing through the non-contact jetting dispenser. 
     
     
         12 . A method of controlling a viscous fluid dispensing system to accurately dispense a viscous fluid onto a substrate, the method comprising:
 directing a first amount of viscous fluid from a viscous fluid supply into a viscous fluid dispenser, the viscous fluid dispenser being operable to start and stop flow of the viscous fluid through an outlet of the viscous fluid dispenser onto a substrate;   using a gas flow meter device operatively coupled to the viscous fluid supply to produce gas flow meter output signals corresponding to the flow rate of the first amount;   discharging the first amount from the outlet onto a weigh scale coupled to a controller, the weigh scale producing weigh scale output signals proportional to the mass of the first amount; and   performing a responsive control function in a closed loop manner by adjusting at least one dispensing parameter using the gas flow meter output signals and the weigh scale output signals.   
     
     
         13 . The method of  claim 12 , wherein performing the responsive control function further comprises adjusting a flow rate of the viscous fluid being dispensed through the outlet using specific gravity of the first amount. 
     
     
         14 . The method of  claim 12 , wherein performing the responsive control function further comprises adjusting the dispensing time using specific gravity of the first amount. 
     
     
         15 . The method of  claim 12 , further comprising:
 determining the mass of the first amount using the weigh scale output signals; and   determining a volume of the first amount using the gas flow meter output signals.   
     
     
         16 . The method of  claim 15 , wherein determining the volume of the first amount further comprises integrating the gas flow meter output signals obtained from the gas flow meter device using the controller. 
     
     
         17 . The method of  claim 16 , wherein performing the responsive control function further comprises:
 calculating a specific gravity of the first amount using the mass and volume of the first amount; and   adjusting the at least one dispensing parameter using the specific gravity of the first amount.   
     
     
         18 . The method of  claim 16 , wherein performing the responsive control function further comprises:
 calculating a density of the first amount using the mass and the volume of the first amount; and   adjusting the at least one dispensing parameter using the density of the first amount.   
     
     
         19 . The method of  claim 12 , wherein the gas flow meter output signals and the weigh scale output signals form an output data set, and performing the responsive control function further comprises adjusting the at least one dispensing parameter using a specific gravity of the first amount calculated using the output data set. 
     
     
         20 . The method of  claim 12 , wherein the gas flow meter output signals and the weigh scale output signals form an output data set, and performing the responsive control function further comprises adjusting the at least one dispensing parameter using a density of the first amount calculated using the output data set. 
     
     
         21 . The method of  claim 12 , wherein the gas flow meter output signals and the weigh scale output signals form an output data set, the method further comprises comparing the output data set to a reference data set stored in the controller.