Abstract:
A filtration tester has a scale, a collector disposed on the scale, a pump having an outlet aligned with an opening of the collector, and a force sensor connected to the pump.

Description:
BACKGROUND  
       [0001]     When designing various systems or devices, such as fluid delivery systems, e.g., ink delivery systems, preliminary testing is often performed to determine how these systems or devices are going behave during operation, and to perhaps determine if or when certain failures may occur. For example, for ink delivery systems, it is important to investigate whether ink delivery nozzles will be come clogged or partially clogged over time, leading to reduced printing performance. In many cases, it may take impractical lengths of time to determine how a device or system will behave, especially well into the system&#39;s or device&#39;s lifecycle. Therefore, tests are often developed to be conducted for reduced times that simulate operation of a system or device over a much longer time. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0002]      FIG. 1  is a block diagram of an embodiment of a filtration tester, according to an embodiment of the present disclosure.  
         [0003]      FIG. 2  is a front isometric view of an embodiment of a filtration tester, according to another embodiment of the present disclosure.  
         [0004]      FIG. 3  is a detailed view of an embodiment of a syringe pump of an embodiment of a filtration tester, according to another embodiment of the present disclosure.  
         [0005]      FIG. 4  presents exemplary data for flows through a filter, according to another embodiment of the present disclosure.  
         [0006]      FIG. 5  presents exemplary nozzle performance data, according to another embodiment of the present disclosure. 
     
    
     DETAILED DESCRIPTION  
       [0007]     In the following detailed description of the present embodiments, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific embodiments that may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice disclosed subject matter, and it is to be understood that other embodiments may be utilized and that process, electrical or mechanical changes may be made without departing from the scope of the claimed subject matter. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the claimed subject matter is defined only by the appended claims and equivalents thereof.  
         [0008]      FIG. 1  is a block diagram of a filtration tester  100 , according to an embodiment. Filtration tester  100  includes a dispenser (or pump)  105 , e.g., a syringe pump, adapted to receive a filter  110  for testing. The filter may be of glass, paper, metal or plastic, have various pore sizes, and have various constructions. An actuator  115  actuates pump  105 . For a syringe pump, actuator  105  is an air-activated piston disposed in an air cylinder. A force sensor  120 , e.g., a load cell, is used to determine the force applied to a liquid, e.g., ink, as it is pumped by pump  105  through filter  110  and into a collector  125 . Collector  125  is disposed on a scale  130  that measures the mass of liquid that flows through the filter  110  and into collector  125  at a plurality of time instants.  
         [0009]     For one embodiment scale  130  has a data output port  136 , e.g., an RS-232 port, coupled to a data input port  138 , e.g., RS-232 port, of a controller (or computer)  140  that for another embodiment, is a personal computer. For various embodiments computer  140  may be external to tester  100  or an integral component of tester  100 . A data output of force sensor  120  is also coupled to computer  140 . An input of actuator  115  is coupled to an output of computer  140  for receiving inputs therefrom based on inputs to computer  140  from scale  130 . For another embodiment, force sensor  120  and actuator  115  interface with computer  140  via a data acquisition board  145  within computer  140 . For some embodiments, scale  130  may connect to data acquisition board  145 . For another embodiment, the output of force sensor  120  is amplified using an amplifier  122  disposed between force sensor  120  and computer  140 . For another embodiment, a DC power supply  170  powers force sensor  120 , scale  130 , and regulation of actuator  115 .  
         [0010]     For one embodiment, computer  140  has a user interface  146  that includes a display device  147 , such as a monitor, and a user input device  148 , such as a keyboard. For some embodiments, user input device  148  may be a portion of display device  147  in the form of soft-touch keys. A printer  162  may be connected to computer  140  for one embodiment and for another embodiment may be an integral component of tester  100 . For one embodiment, computer  140  is adapted to transmit data corresponding to a data network  164  via an interface  166 . For one embodiment, data network  164  is a Local Area Network (LAN), the Internet, or the like, and interface  166  is a network adaptor (or network interface card).  
         [0011]     For another embodiment, computer  140  is adapted to perform methods in accordance with embodiments of the present disclosure in response to computer-readable instructions. These computer-readable instructions are stored on a computer-usable media  150  of computer  140  and may be in the form of software, firmware, or hardware. In a hardware solution, the instructions are hard coded as part of a processor, e.g., an application-specific integrated circuit (ASIC) chip, a field programmable gate array (FPGA), etc. In a software or firmware solution, the instructions are stored for retrieval by computer  140 . Some additional examples of computer-usable media include static or dynamic random access memory (SRAM or DRAM), read-only memory (ROM), electrically-erasable programmable ROM (EEPROM or flash memory), magnetic media and optical media, whether permanent or removable.  
         [0012]      FIG. 2  is a front isometric view of a filtration tester  200 , according to another embodiment. Filtration tester  200  includes a syringe pump  205  that is shown in more detail in  FIG. 3 , according to another embodiment. A filter  210  formed integrally with a housing  212 , for one embodiment, is removably attached to an exit of syringe pump  205 , e.g., by threading, to be tested. For one embodiment, filter  210  is a commercially available syringe filter.  
         [0013]     An air-activated piston  213  disposed in an air cylinder  214  ( FIGS. 2 and 3 ) actuates syringe pump  205  when air flows into to air cylinder  214 , via a tube  217  ( FIG. 2 ) from an air regulator  216  that can be electrically controlled using control signals from a computer, such as computer  140  of  FIG. 1 . The air causes piston  213  to extend from cylinder  214  into engagement with a plunger  218  of syringe pump  205 . Extending piston  213  moves plunger  218  into a barrel  219  of syringe pump  205 . Plunger  218  in turn pushes against a liquid  221  e.g., ink, within barrel  219  and pushes liquid  221  through filter  210  so that it exits housing  212 , as shown in  FIG. 3 . For one embodiment, a biasing device  250 , such as a spring, is connected to piston  213  for biasing piston in a retracted position within cylinder  214 . That is, biasing device  250  retracts piston  213  when the air pressure thereon is sufficiently reduced or removed.  
         [0014]     A load cell  220  is disposed between piston  213  and plunger  218 , as shown in  FIG. 3 , and is used to determine the force applied to plunger  218  by piston  213  and thus the force applied to liquid  221 . Load cell  220  is coupled to a computer, such as computer  140  of  FIG. 1 , for sending output signals thereto.  
         [0015]     The liquid  221  flows through an open top of a collector (or cup)  225  after passing through filter  210  ( FIG. 2 ). Collector  225  is disposed on a scale  230  that includes a data port  236 , such as an RS-232 port, that is coupled to a computer, such as computer  140  of  FIG. 1 . Scale  230  measures the mass of liquid that flows through the filter  210  and into collector  225  at a plurality of time instants.  
         [0016]     For another embodiment, filtration tester  200  is adapted to receive syringe pumps of different sizes. For one embodiment, a turret  260  accomplishes this. Specifically, turret  260  includes a plurality of slots  265  respectively sized to receive different sized syringe pumps. Rotating turret  260  so a portion of a slot  265  aligns with collector  225  selects that slot  265 , as shown in  FIG. 2 .  
         [0017]     For one embodiment, tester  200  operates in a substantially constant-force (or constant-pressure) mode of operation. During the constant-force mode, the pressure applied to syringe pump  205  is maintained a substantially fixed pre-selected value. For one embodiment, the user inputs this pressure via the computer, e.g. in response to a prompt from the computer. For another embodiment, the computer prompts the user to input the air pressure, and then instructs air regulator  216  to set that pressure in response to the input. For some embodiments, the computer monitors the force on the load cell. If the force exceeds a predefined upper control limit or drops below a predefined lower control limit, the computer instructs air regulator  216  ( FIG. 2 ) to respectively decrease or increase the pressure to bring the force measured by the load cell back within the control limits. The applied force causes liquid  221  to flow though filter  210  and into collector  225  ( FIG. 2 ), and the computer receives signals from scale  230  representative of the instantaneous mass in the collector at a plurality of sample times. For one embodiment, the user inputs the duration of the sample times, i.e. the sample rate, into the computer, e.g., in response to a prompt from the computer.  
         [0018]     For another embodiment, tester  200  operates in a substantially constant-mass-rate mode of operation. That is, the mass flow rate through the filter is maintained substantially constant. For one embodiment, the user inputs the desired mass flow rate into the computer, e.g., in response to being prompted by the computer. After the desired mass flow is entered into the computer, the computer instructs air regulator  216  ( FIG. 2 ) to set the nominal pressure for attaining that mass flow rate for one embodiment. For some embodiments, the user may be prompted for test profile data characterizing a particular test run, such as the filter type, filter pore size, filter construction, control liquid type, if control liquid is used, a user identification, sample rate, test identification, an destination address on a data network to which test results can be sent, etc., before starting a test run.  
         [0019]     The nominal pressure causes syringe pump  205  to expel liquid through filter  210  and into collector  225  ( FIG. 2 ). Scale  230  sends signals indicative of the collected mass at two or more sample times to the computer, and the computer determines the mass flow rate, e.g., from the amount of mass collected for during given sample time interval. If the mass flow rate exceeds a predefined upper control limit or is below a predefined lower control limit, the computer instructs air regulator  216  ( FIG. 2 ) to respectively decrease or increase the pressure to bring the mass flow rate within the control limits.  
         [0020]     For some embodiments, when syringe pump  205  is empty, the signals the computer receives from scale  230  indicate that the mass in collector  225  is no longer changing. In response, the computer instructs air regulator  216  to turn off the air, and biasing device  250  retracts piston  213 . For another embodiment, when signals the computer receives from scale  230  indicate that the change in the mass in collector  225  is below a predetermined threshold, the computer determines that syringe pump  205  is empty or that the filter is clogged. For one embodiment, this is indicative of an end point of a test run, and the computer instructs air regulator  216  to turn off the air, and biasing device  250  retracts piston  213 .  
         [0021]      FIG. 4  presents exemplary filtration data for three different inks obtained from operating filtration tester  200  in the constant-force mode, according to an embodiment. Note that ink  1  filters the slowest, with ink  2  filtering faster than ink  1 , and ink three filtering slightly faster than ink  2 .  
         [0022]     The filtration data of  FIG. 4  can be linked to the performance (or health) of ink ejection nozzles of an ink ejection device, such as an ink-jet print head. This is illustrated in  FIG. 5 , according to another embodiment.  FIG. 5  presents nozzle performance as a percentage of the total nozzles that are missing (or inoperative) for the inks of  FIG. 4 . The closed data symbols correspond to the nozzle performance during printing at the top of a page, while the open data symbols correspond to the nozzle performance during printing at the bottom of the page. Moreover, printing at the top of the page, for one embodiment, occurred immediately after the nozzles were removed from a simulated storage condition corresponding to a capped state of the nozzles. It is seen that nozzle performance of  FIG. 5  correlates with the filtration data of  FIG. 4 . That is, the largest number of missing nozzles both at the top and bottom of the page occurs for ink  1  that had the lowest filtration rates. The higher filtration rates of inks  2  and  3  in  FIG. 4  are reflected in the increased nozzle performance (i.e., fewer missing nozzles) in  FIG. 5 . For some embodiments, multiple inks may be tested using filtration tester  200 , and the computer may compare the filtration data of the respective inks and indicate which ink will result in better nozzle performance based on the comparison.  
         [0023]     The simulated storage condition, for one embodiment, was accomplished by placing the inks and nozzles in a heated chamber, where the heat acts to accelerate the storage time. However, four weeks, was required to obtain the performance data of  FIG. 5 . Note that the filtration data of  FIG. 4  infers the performance data of  FIG. 5  and can be obtained, for this example, in less than one day.  
       CONCLUSION  
       [0024]     Although specific embodiments have been illustrated and described herein it is manifestly intended that the scope of the claimed subject matter be limited only by the following claims and equivalents thereof.