WO2019017963A1

WO2019017963A1 - Fluid level detector

Info

Publication number: WO2019017963A1
Application number: PCT/US2017/043260
Authority: WO
Inventors: Patrick V Boyd; David Olsen
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2017-07-21
Filing date: 2017-07-21
Publication date: 2019-01-24

Abstract

In one example, a system with a fluid level detector includes a fluid actuator assembly with a fluid chamber and a fluid container (40) with a fluid reservoir (44) coupled to the fluid chamber (22). A pressure regulation bag (42) is disposed within the fluid reservoir (44) along with a fluid level sensor (60) to provide an estimate of a fluid level in the fluid reservoir. The fluid level sensor (60) is disposed such that when the fluid reservoir (44) contains fluid, the fluid is not detected in contact with a top of the fluid level sensor once the pressure regulation bag is at a regulation point. When the pressure regulation bag (42) is maximally inflated to fill the fluid chamber (22) with the fluid, the estimate of the fluid level represents a measurement of an amount of fluid in the fluid reservoir (44) once the pressure regulation bag returns to the regulation point.

Description

FLUID LEVEL DETECTOR

BACKGROUND

[0001] Fluid jet printheads are now being used in printer device applications that use expensive media and create high-quality output. The fluid jet printheads are also used in other devices to transfer fluids such as in 3D printing, drug delivery, micro-assays, and the like. Printer devices may produce text and images on media through drop-on-demand ejection of fluid drops using 'Inkjet fluid actuators." In this disclosure "fluid actuators" or "actuators" include both ejecting fluid nozzles and orifices as well as non- ejecting actuators such as used in microfluidic pumps in both printers and other fluidic devices. Fluid may be supplied to various component parts from or through fluid reservoirs used as on-axis or off-axis fluid supplies.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] The disclosure is better understood with reference to the following drawings. The elements of the drawings are not necessarily to scale relative to each other. Rather, the emphasis has instead been placed upon clearly illustrating the claimed subject matter. Furthermore, like reference numerals designate corresponding similar parts through the several views. In the interest of brevity, parts discussed in earlier drawings may not be further discussed in later drawings in which they are shown.

[0003] Fig. 1 A is a block diagram of an example fluid system;

[0004] Fig. 1 B is a block diagram of an example fluid container and example fluid actuator assembly usable in the example fluid system of Fig. 1 A;

[0005] Fig. 2 is an example chart of bag volume vs. fluid level for an example container illustrating principles of the claimed subject matter;

[0006] Fig. 3 is a block diagram of an example controller usable for the example fluid system of Fig. 1 A;

[0007] Fig. 4 is a flowchart of additional example instructions executed by the controller of Fig. 3 for the example fluid system;

[0008] Fig. 5 is an example internal view of an example fluid container and an example fluid actuator assembly; and

[0009] Figs. 6A and 6B are internal views of an example fluid actuator assembly respectively illustrating a partial and full fluid level of the fluid chamber within.

DETAILED DESCRIPTION

[0010] The amount of air within a fluid reservoir and its relative pressure to ambient air pressure and temperature may affect the fluid level. If a fluid reservoir runs out of fluid, printhead damage may occur as a result of firing without fluid in the actuators and/or time is wasted in operating a printer without achieving a completed printed image. This waste is particularly time- consuming in the printing of large images which often are printed in an unattended manner on expensive media. Accordingly, there is a general inability to predict an out of fluid condition when a large portion of the fluid in a fluid container may be used on a large image.

[0011] For conciseness and definiteness, the following description is directed in terms of fluid systems having multiple fluid actuators coupled to at least one fluid reservoir, such as with inkjet printhead assemblies coupled to fluid ink reservoirs. However, the claimed subject matter is applicable to many other types of fluid dispensing elements, printheads, and fluidic control devices such as wax-based, piezo-electric, tissue ejectors, 3D printers, biological scaffolding, binders, assay devices, coaters, etc. Accordingly, the claimed subject matter is not necessarily limited to printers that dispense ink as such but is also applicable to many other devices that manipulate fluids in the forms of colorant, chemicals, medicines, materials, fuels, and biological fluids using fluid actuator assemblies (FAA). Moreover, the claimed subject matter is not necessarily limited to printing on ordinary printing media such as paper, plastic sheeting, and the like but rather may be used in devices that can perform incremental printing or fluid placement and movement on virtually any medium including clothing, cloth, food, wood, metal, glass, plastics, ceramics, billboards, etc.

[0012] There are many issues with being able to read accurately an amount of fluid within a fluid based system. As ink-based fluid systems have migrated to larger systems, the cost of ink and media have accordingly increased as well. A failure such as running out of an ink fluid in the middle of a print job not creates unwanted waste of media and ink, but it may also create delays in processing and require user or technician time to restock the fluid supplies or replace damaged printheads. Accordingly, accurately knowing the amount of remaining fluid volume would help prevent

catastrophic printhead or other fluidic actuator assembly failures and allow for better job execution.

[0013] Compliant members in the fluid supplies are used to control back-pressure and account for atmospheric variations that can make the physical level of fluid in the reservoir not be representative of the actual amount of fluid remaining in the system. Further, due to market segments, regionalization, and use of different units of volume (e.g. metric vs. English units), producing a single fluid reservoir that works for all the configurations may be difficult to achieve. In some fluid systems, such as ink-jet printers and 3D-printers, the servicing of components such as printhead assemblies (PHA) may use undetermined amounts of ink depending on the reason for the servicing operation. Accordingly, the claimed subject matter disclosed herein is directed to an improved fluid level sensor and system to create an accurate "gas gauge" fluid level detector for the remaining level of fluid in a fluid reservoir in a fluid-based system. The more accurate fluid "gas gauge" fluid level detector can be used to control printing or other fluid operations as well as be displayed for users via computer monitors or a fluid device front panel.

[0014] Fig. 1 A is a simplified block diagram of an example fluid-based system 1 0, in this example, an ink-jet printing system. The claimed subject matter may also be used with small, personal, intermediate, and large scale printer devices and plotters as well as 3D printers. Such additional printer devices may include desktop printers, portable printers, hand-held printers, bar-code printers, heat-transfer printing, fax machines, thermal printers, ATM- machine receipt printers as just a few examples. Those skilled in the art will understand how to interpret the following discussion and associated drawings with respect to these many other types of printing devices and fluid-based products.

[0015] In this system 10, a printhead based fluid actuator assembly (FAA) 20 is supported on a carriage 1 2 that may be manipulated relative to a print medium 14. In various systems 10, the FAA 20 may be stationary and a print medium 14 transported by a print media transport 1 6 in single or multiple directions relative to a printhead 30 with multiple actuators on the FAA 20. In other examples, the print medium 14 may be stationary and the print media transport 16 moves the printhead 30 across the print medium in two directions. In several examples, the print medium 14 is moved in a first direction with respect to the carriage 12 and the carriage 12 in scans the printhead 30 in a second direction orthogonal to the first direction. The printhead 30 may have single or multiple printhead dies (not shown) each with multiple actuators. The FAA 20 may contain a single or multiple ink fluid chambers and be further coupled to fluid containers 40 that store ink, fixers, coaters, binders, or other fluids. For an ink jet printer, there are typically at least four fluid containers 40 holding separate supplies of black (K), magenta (M), yellow (Y), and cyan (C) inks. There may be more or fewer containers in other fluid systems 10 and the fluids may be other types than just ink. In this example, printhead 30 may include four elongated printhead dies (not shown) such as for the black, cyan, magenta, and yellow ink fluids. In other examples, printhead 30 may include multiple printhead dies, each die containing a single or multiple fluid-feed slots arrays. The printhead dies may be arranged parallel to one another across the width of printhead 30. In some instances, FAA 20 may have a single printhead 30 with four dies, however, other configurations are possible, such as FAAs 20 having multiple printheads 30, each with more or less dies. Printhead 30 may be more broadly characterized as an actuator assembly that may have various combinations of ejectable and non-ejectable actuators depending on the desired application. For instance, a fluidic mixing printhead 30 may have non-ejectable actuators used to pump and control the flow of fluids before transferring the fluids to another printhead 30 that may have ejectable actuators.

[0016] A controller 100 may include single or multiple processors 1 10 (Fig. 3) having single or multiple cores that are coupled to a tangible and non- transitory computer readable medium (CRM) 120. The processor 1 10 may be a separate processor or a system-on-a-chip (SOC) processor using commercial or custom central processing units and/or digital signal processors. The CRM 120 may include software and/or firmware routines to be executed by the processor. In Fig. 1 A, the controller 100 includes a FAA fluid fill routine 102 that may be used to transfer fluid, such as ink, between a fluid container 40 and the FAA 20 and ultimately the printhead 30 using a hyperinflation cycle before reading a fluid level sensor in fluid container 40. The controller 100 is also electrically or otherwise coupled to a service station 50 having an air pump 52. In other examples, the air pump 52 may be remote from the service station 50. The air pump 52 may be fluidically coupled through the FAA 20 to a fluid reservoir 44 in each fluid container 40 as shown in Fig. 4.

[0017] The controller 100 may include additional routines (not shown) in the CRM to allow the print media transport 16 to move print medium 14 and/or carriage 12 in relative motion to each other to allow the printhead 30 to place fluid on a surface of print medium 14.

[0018] Fig. 1 B is a schematic diagram of an example fluid-based system 1 0 illustrating the coupling of an example fluid container 40 with an example FAA 20 such as for use in the example system 10 of Fig. 1 A. The fluid container 40 may include a pressure regulation bag 42 for controlling backpressure with the aid of a reservoir air port 41 . Fluid container 40 also may include a fluid level sensor 60 within the fluid reservoir 44. During the life of the fluid container 40, the fluid level sensor 60 may be used by the controller 100 to read the fluid level 66 generally after the pressure regulation bag 42 has been maximally inflated or hyper-inflated and allowed to return to a nominal regulation point.

[0019] This hyperinflation cycle prior to the reading of the fluid level sensor 60 prevents inaccurate fluid level 66 readings due to different pressure regulation bag volumes caused by conditions that would affect a proper reading of the fluid volume inside the fluid reservoir 44. A hyperinflation cycle prior to the reading of the fluid level sensor 60 also ensures that the fluid level 66 in a fluid chamber 22 in the FAA 20 the air pressure within the fluid reservoir 44 is consistent with retreating levels of bag volume as fluid is withdrawn. This prior hyperinflation cycle approach to fluid level sensing addresses many issues that have plagued past attempts to create an accurate "gas gauge" for a fluid supply.

[0020] For instance, the compliant features within fluid supplies that protect against atmospheric pressure changes and out-of-ink (OOI) resets have made the fluid levels 66 not uniformly representative of the amount of fluid within the fluid supply. Further, several fluid fill levels may be done for separate SKU's (stock keeping units) to fit market segments, thereby making the setting of initial amounts of fluid within the supply difficult. With the improved "gas gauge" fluid level detector approach disclosed herein, accurate amounts of fluid may be determined regardless of the initial fluid fill level or state of the pressure regulation.

[0021] FAA 20 may have a small "flux capacitor" 29 air reservoir (Fig. 6A) within the fluid chamber 22 for pressure stabilization and may be fluidically connected to fluid supplies, such as fluid containers 40, in the system 1 0 through FAA inlet fluid ports 25. FAA 20 may also be electrically connected to the printer controller 10 and contain separate fluid level sensors and readable and/or programmable memory. FAA 20 may also relay communication signals to/from the processor 1 10 and the fluid container 40. In this example, the FAA 20 has a fluid chamber 22 to accept fluid via a FAA inlet fluid port 25 from fluid container 40 via a container fluid port 45. The FAA inlet fluid port 25 may be coupled to the container fluid port 45 using additional connectors, couplings, hoses, and fittings.

[0022] The fluid container 40 includes a fluid reservoir 44 for holding various amounts of fluid. The fluid reservoir 44 may be configured in various SKUs or configurations to have different volumes and may be filled, refilled, or replaced with different levels of fluid. For instance, the fluid reservoir 44 may be filled to a Max Fill level 65 or any different initial fill levels 46 between the Max Fill Level 65 and a top 62 of a fluid level sensor 60. Further, the fluid reservoir 44 may have a pressure regulation bag 42 disposed within and surrounded partially or fully by the fluid within the fluid container 40. The top 62 of the fluid level sensor 60 may be disposed at or near the beginning of an air regulation point 48 where the fluid regulation bag 42 maintains a substantially uniform volume during the life of the fluid container 40. The pressure regulation bag 42 may be made of a compliant elastomeric material and/or it may contain an internal spring 43 (Fig. 5) or another flexible member to maintain or manipulate the shape and volume of the pressure regulation bag 42 during operation of fluid device 10.

[0023] The pressure regulation bag 42 may be designed and configured to change volume and/or shape based upon ambient air condition outside of the fluid container 40 in order to maintain a back-pressure within the fluid reservoir 44 to prevent fluid from uncontrollably leaking from a printhead 30 or another actuator mechanism in FAA 20. The back-pressure is also maintained by the pressure regulation bag 42 to not be so great as to withdraw fluid from the actuators of printhead 30 thereby causing voids or "nozzle-outs" during printing or other fluidic operations. The back-pressure regulation may be assisted with a reservoir air port 41 that may be an air bubble regulator and check valve or it may be an active value. There are several different methods of controlling the air back-pressure within the fluid reservoir 44 that may be modified to operate similarly to the described matter herein of maintaining a substantially consistent bag volume over a large range of liquid volume within the fluid reservoir 44.

[0024] The fluid container 40 may also include a fluid level sensor 60 disposed within the fluid reservoir 44 and when in use, the fluid level sensor 60 may be in contact with the fluid physically, optically, acoustically, electrically, or otherwise depending on the sensor technology used. To allow for different levels of fluid for different configurations of fluid container 40, a fluid level sensor 60 reading is used when the pressure regulation bag 42 operates at or below a regulation point 48 (see Fig. 2). During use, the pressure regulation bag 42 usually declines from a nominal regulation point 48 volume while ink or other fluid is withdrawn from the fluid reservoir 44, but due to ambient air pressure or other condition changes, the pressure regulation bag 42 may actually expand or contract significantly from the nominal regulation point 48. In this example, the pressure regulation bag 42 may be designed and configured that over a wide range of fluid volume during nominal use, the volume of the pressure regulation bag 42 maintains substantially a consistent volume within a stable air pressure and temperature environment. Accordingly, a top 62 of the fluid level sensor 60 is located where the pressure regulation bag substantially first encounters this nominal regulation point 48 based off the design of the fluid container 40 and its backpressure regulation system. When the fluid level 66 within the fluid reservoir 44 is detected at or over the top 62 or in contact with the top of the fluid level sensor 60, a "full" level 64 is detected by the fluid level sensor 60 and controller 100. To account for the different starting levels of fluids in this "full" level 64 state, drop counting may be used to allow the controller 100 to keep track of the amount of fluid with the fluid reservoir 44 based on different starting levels programmed into a memory in the fluid container for each configuration.

[0025] The pressure regulation bag 42 is further configured to be coupled to the pump 52 via an air port 47 in the fluid container 40. To ensure that the level of fluid is at a consistent level before taking a reading of the fluid level sensor 60 when the fluid is detected below the top 62 of the fluid level sensor 60, the pressure regulation bag 42 is maximally inflated and allowed to return to its operational nominal regulation point 48. By maximally inflating the pressure regulation bag 42 excess air within the fluid chamber 22 may be expelled and the fluid chamber 22 refilled with fluid from the fluid reservoir 44. Also, by maximally inflating the pressure regulation bag 42 and allowing for its return to the regulation point 48, any changes in the pressure regulation bag 42 due to changes in air pressure or volume change due to fluid transferred to the FAA 20 can be compensated out. The remaining fluid level 66 with the fluid reservoir 44 is then representative of the remaining fluid amount in the fluid reservoir 44.

[0026] Hyper-inflating the pressure regulation bag 42 to maximally inflate it is characteristically done during initial printer start-up and when replacing or refilling a depleted fluid container 40. This hyperinflation cycle is extended to be used prior to reading the fluid level sensor 60 in order to increase the accuracy of determining the remaining level of fluid in an operational fluid container 40. Introducing fluid into a FAA 20 may also be referred to as "priming" the FAA 20. When priming, the FAA 20 may not be completely filled with fluid unless froth (air, ink bubbles, etc.) is removed from the FAA 20. Therefore, the pump 52 may be used to pressurize the pressure regulation bag 42 to is max volume (hyper-inflated) and thereby push fluid from the fluid container 40 into the fluid chamber 22 by increasing the pressure within the fluid reservoir 44. The fluid chamber 22 may have a chamber air port 28 used to vent air during the hyperinflation cycle or to be used as a back-pressure regulator during the FAA 20 operation, such as with bubble regulators and check valves. There are several ways of implementing the back-pressure regulation in printhead assemblies that may be adapted for use with this described gas gauge fluid level detector method. Accordingly, the fluid chamber 22 may be vented actively or passively using valves or "bubble regulation ports," respectively, that are coupled to ambient air to draw air and/or froth from FAA 20 either to the fluid reservoir 44 or out of FAA 20 to another location in the service station 50. This pressure/vent hyperinflation cycle may be repeated multiple times until a sensor in the fluid chamber 22 indicates that the FAA 20 is full or until a predetermined number of cycles are completed.

[0027] Fig. 2 is a chart 200 of an example method of creating a gas gauge 70 fluid level detector. The chart 200 illustrates the bag volume 90 of the pressure regulation bag 42 on the vertical or "Y" axis. The horizontal or "X" axis illustrates the fluid level 66 within the fluid reservoir 44. A set of hyperinflation cycles 80 is shown as used to fill the fluid chamber 22 in the FAA 20 and return the bag volume 90 to a nominal regulation point 48. The fluid reservoir 44 has a container max level 65, a top level 62 of fluid sensor 60, and an out-of-fluid level 68. The fluid level 66 within the fluid reservoir 44 may be split between a full level 64 where drop counting may be used and an accurate fluid level sensor reading range 63 where the use of the fluid level sensor 72 may be performed. In the full level 64 range, there may be different initial fill levels 46 depending on different fluid container 40 models or configurations. [0028] When a new fluid container 40 is installed the pressure regulation bag 42 is hyper-inflated to bring the pressure regulation bag 42 to its maximally inflated volume 92 at point "a". As the air regulator (i.e. a "bubble regulator" or active valve system) in the fluid container 40 equalizes the internal air pressure to the desired back-pressure, the bag volume 90 will decrease to point "b" where the fluid level 66 within the fluid container 40 is at its particular initial fill level 46 within the full level region 64. Each

configuration or SKU of the fluid container 40 may have a pre-configured initial amount of ink or other fluid programmed into a memory 23 and readable by the controller 1 00. During the "full level" 64 range drop counting may be used to count the number of drops of fluid used by actuators in FAA 20. If the outside ambient air pressure, temperature, or other condition (such as bag volume change due to air pressure change 94) causes the pressure regulation bag 42 to increase or decrease in volume, at point "c" a

hyperinflation cycle can be performed to increase the bag volume 90 to the maximally inflated 92 level as shown in point "d" returning to point "a". The back-pressure air regulator system used within the fluid container 40 then allows the pressure within the fluid container 40 to return to the nominal regulation point 48 for the current fluid level 66. When at point "e", the fluid level 66 within the fluid container 40 is below the top 62 of the fluid level sensor 60. The gas gauge 70 fluid level detector may use the fluid level sensor 60 to get an accurate fluid level sensor reading 63 by performing at point "f" a hyperinflation cycle prior to the reading. In some situations, when a hyperinflation cycle has recently been performed, then within the accurate sensor reading range 63, the fluid level sensor 60 reading may be taken without first performing the hyperinflation cycle. As the fluid within the fluid reservoir 44 continues to decline based on FAA 20 use to point "g", a hyperinflation cycle 98 may be performed to maximally inflate the pressure regulation bag 42 through point "h" and have it relax back to point "g" before taking a reading of fluid sensor 60 to ensure an accurate reading when the fluid level 66 is near the out-of-fluid level 68. [0029] Fig. 3 is a block diagram of the controller 100 of Fig. 1 . The controller 100 may include a processor 1 1 0 coupled to a tangible and non- transitory computer readable medium 1 20 that includes instructions formed in routines, subroutines, modules, or other logical blocks. For instance, the FAA fluid fill routine 102 may be composed of a first routine 122 to maximally inflate the pressure regulation bag 42 and a second routine 1 24 to read a fluid level sensor 60. For example, a non-transitory CRM 1 20 may include instructions that when read and executed by the processor 1 10 cause the processor 1 1 0 to 1 )maximally inflate a pressure regulator bag 42 disposed within a fluid reservoir 44 of a fluid container 40 containing fluid to fill a fluid chamber 22 within a FAA 20, the fluid reservoir 44 coupled to a fluid level sensor 60, wherein the fluid level sensor 60 is disposed within the fluid reservoir 44 such that fluid is not in contact with a top 62 of the fluid level sensor 60 once the pressure regulation bag 42 is at a regulation point 48; and 2) read the fluid level sensor 60 to provide an estimate of a fluid level 66 in the fluid reservoir 44 that represents a measurement of an amount of fluid in the fluid reservoir 44 after the pressure regulation bag 42 is maximally inflated and the pressure regulator bag 42 returns to the regulation point 48.

[0030] The various examples described within this disclosure may include logic or a number of components, modules, or constituents. Modules may constitute either software modules, such as code embedded in tangible non-transitory machine or computer readable medium (CRM) 120 or hardware modules. A hardware module may be a tangible unit capable of performing certain operations and may be configured or arranged in certain manners. In one example, computer systems or hardware modules of a computer system may be configured by software (e.g. an application, or portion of an application) as a hardware module that operates to perform certain operations as described herein.

[0031] In some examples, a hardware module may be implemented as electronically programmable. For instance, a hardware module may include dedicated circuitry or logic that is permanently configured (e.g. as a special- purpose processor, state machine, a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC) to perform certain operations. A hardware module may also include programmable logic or circuitry (e.g. as encompassed within a general-purpose processor 1 10 or other programmable processors) that is temporarily configured by software to perform certain operations.

[0032] The computer readable medium 120 allows for storage of sets of data structures and instructions (e.g. software, firmware, logic) embodying or utilized by any of the methodologies or functions described herein. The instructions may also reside, completely or at least partially, with the static memory, the main memory, and/or within the processor 1 10 during execution by the printer controller 100. The main memory and the processor memory of printer controller 100 also constitute CRM 1 20. The term "computer-readable medium" 120 may include single medium or multiple media (centralized or distributed) that store the instructions or data structures. The CRM 120 may be implemented to include, but not limited to, solid state, optical, and magnetic media whether volatile or non-volatile. Such examples include, semiconductor memory devices (e.g. Erasable Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-only Memory (EEPROM), and flash memory devices), magnetic discs such as internal hard drives and removable disks, magneto-optical disks, and CD-ROM (Compact Disc Read-Only Memory) and DVD (Digital Versatile Disc) disks, as just some examples.

[0033] Fig. 4 is a flowchart of other example routines 150 of instructions which may be stored in CRM 1 20 within routines for being read and executed by processor 1 10. In block 152, the instructions allow detecting that fluid within the fluid reservoir 44 is in contact with a top 62 of the fluid level sensor 60. In block 154 the instructions allow for counting a number of drops of fluid used by a fluid jet printhead 30 coupled to the fluid container 40 during a full level 64 detected by the fluid level sensor 60. Other instructions in block 1 56 allow for detecting that fluid within the fluid reservoir 44 is not in contact with the top 62 of the fluid level sensor 60 prior to in block 158 reading the fluid level sensor 60 to provide an estimate of the fluid level 66 in the fluid reservoir 44. In block 160, the instructions may create a gas gauge 70 fluid level detector using a combination of 1 ) the number of drops of fluid when the fluid within the fluid reservoir 44 is detected in contact with the top 62 of the fluid level sensor 60, and 2) an output of the fluid level sensor 60 when the fluid within the fluid reservoir 44 is detected not in contact with the top 62 of the fluid level sensor 60. In block 162, the instructions may allow for reading the contents of a memory 23 on the fluid container 40 to determine a model of the fluid container 40. In block 1 64 the instructions may then set an initial fluid level 46 based on the determined model of the fluid container 40.

[0034] Fig. 5 is an example internal view 300 of an example fluid container 40 and an example fluid actuator assembly 20 that may be used in an example fluidic system 10. A carriage 12 includes a FAA 20 and a fluid container interface 55.

[0035] The fluid container interface may include a carriage electrical interface 54 for coupling to a container electronic interface 61 on the fluid container 40 which may include coupling to a memory 23 for storing configurations and the fluid sensor 60 for performing readings. The memory 23 coupled to the container electrical interface 61 may be used to store an estimate of fluid level 66 and a count of a number of drops representing an amount of fluid used by a FAA 20 when a full level 64 is detected by the fluid level sensor.

[0036] The fluid container interface 55 may also have a carriage air port 58 for mating and coupling with the container air port 47 to couple to the pressure regulation bag 42. The carriage air port 58 may be further coupled to the air pump 52 of Fig. 1 A. The air pump 52 may be used to maximally inflate the pressure regulation bag 42. The pressure regulation bag 42 may include an internal spring 43 to provide a counter-pressure against the internal air-pressure and helps in maintaining the desired back-pressure and nominal regulation point 48. The FAA 20 includes a fluid chamber 22 that may be broken up into single or multiple sub-chambers to provide air bubble and particulate removal and back-pressure regulation. The fluid chamber 22 has a fluid level 66 that varies depending upon FAA 20 use in fluidic system 10. The fluid chamber 22 may have a valve 28 or equivalent vent, regulator and check value, or another back-pressure maintenance device. The fluid container 40 is physically mated with FAA 20 with a mechanical interface for a slight gravitational tilt, carriage electronic interface 54, container electronic interface 61 , a fluidic interface FAA inlet fluid port 25, and container fluid port 45.

[0037] The fluid container 40 includes a fluid reservoir 44 coupled to the fluid chamber 22. In some examples, the fluid container 40 may have an auxiliary reservoir separate from fluid reservoir 44 to change the container maximum initial fill level 46 for the fluid reservoir 44. For instance, in some examples a volume adjustment chamber 49 allows for different initial volumes of fluid to be stored in the fluid reservoir 44. A pressure regulation bag 42 is disposed within the fluid reservoir 44. A fluid level sensor 60 is used to provide an estimate of a fluid level 66 in the fluid reservoir 44 and disposed such that when the fluid reservoir 44 contains fluid, the fluid is not detected in contact with a top 62 of the fluid level sensor 60 once the pressure regulation bag 42 is at a regulation point 48. In some examples, the fluid level sensor 60 may be disposed substantially orthogonal to a gravitational bottom of the fluid reservoir 44 and extend from the top 62 of the fluid sensor 60 to a fluid interface, such as container fluid port 45, at the gravitational bottom of the fluid reservoir. In other examples, the fluid level sensor 60 may be disposed at any angle, such as 30, 45, or 60 degrees to the top of the fluid surface from the gravitational bottom. The fluid container 44 may be rotated or angled slightly as illustrated to allow the fluid in fluid reservoir 44 to flow better to the gravitational bottom.

[0038] The fluid reservoir 44 may be sized to allow fluid within the fluid reservoir 44 to contact or be detected at the top 62 of the fluid level sensor 60 when the fluid within the fluid reservoir 44 is above a predetermined level, such as a designed nominal regulation point 48. A full level 64 may be indicated by physical contact with fluid at the top 62 of the fluid level sensor 60 or the fluid level 66 to be detected at the top 62. The full level 64 may encompass a volume of between about 75% and about 1 00% of the expected fluid capacity of the fluid container 40. This configuration allows for a much larger range of accurate fluid level readings compared to other fluid level detector based gas gauges 70 with FAAs 20. In some instances, the fluid level sensor 60 may be selected from at least one of the group of temperature decay, timing, capacitance, inductance, resistance, reluctance, optical diffusion, optical interference, and optical timing.

[0039] When the pressure regulation bag 42 is maximally inflated to fill the fluid chamber 22 with the fluid, the estimate of the fluid level 66 represents a measurement of an amount of fluid in the fluid reservoir 44 once the pressure regulation bag 42 returns to the regulation point 48. The fluid reservoir 44 may be sized to allow fluid within the fluid reservoir 44 to contact the top 62 of the fluid level sensor 60 when the fluid within the fluid reservoir 44 is above a predetermined level. In some examples, the fluid level sensor 60 may be disposed substantially orthogonal to a gravitational bottom of the fluid reservoir 44 and extend from the top 62 of the fluid sensor 60 to a fluid interface 45 at the gravitational bottom of the fluid reservoir. As noted previously, in some examples, the fluid level sensor 60 may be disposed at any angle, such as 30, 45, or 60 degrees to the top of the fluid surface from the gravitational bottom. The fluid reservoir 44 may include a volume adjustment chamber to allow for different initial volumes of fluid to be stored in the fluid reservoir 44. In some examples, the system 10 may also include an air pump 52 and an air port 47 coupled to the pressure regulation bag 42 and the air pump 52. The air pump 52 may be configured to maximally inflate the pressure regulation bag 42.

[0040] The fluid container 40 may include an electrical interface 41 for coupling the fluid level sensor 60 with the controller 100. Also, a memory may be coupled to the electrical interface 41 to store the estimate of the fluid level 66 and a count of the number of drops representing an amount of fluid used by a fluid jet printhead 30 during a full level 64 detected by the fluid level sensor 60. The full level 64 may be indicated by contact or detection of the fluid at the top 62 of the fluid level sensor 60. In some examples, the full level 64 may encompass a volume of about 85% and about 100% of the expected fluid capacity of the fluid container 40. The fluid level sensor 60 may be implemented with several different technologies. For instance, the fluid level sensor 60 may be based on temperature decay, timing, capacitance, inductance, resistance, reluctance, optical diffusion, optical interference, optical timing, and the like.

[0041] Figs. 6A and 6B are internal views of an example FAA 20 illustrating a partial and full fluid level of the fluid chamber within, respectively. For instance, Fig. 6A shows a FAA inlet fluidic port 25 that accepts fluid from a fluid container 40 and may also be used to expel excess air and or "froth" (fluidic bubbles of air) when a hyperinflation cycle is performed. In this example, the fluid chamber 22 is divided into two sub-chambers, first fluid chamber 26 and second fluid chamber 27. As fluid is drawn into first fluid chamber 26 any air in the supply lines is captured by the flux capacitor 29 and the fluid is deposited into the first chamber 26. As fluid is used by a printhead 30, it is drawn through a fluid filter 24 that removes particulates and also prevents air dissolved in the fluid to reach the printhead 30. The fluid level 66 is the same within the first chamber 26 and the second chamber 27 due to an opening between the chambers allowing for air pressure equalization. A FAA vent 28 may be used to set the back-pressure within the FAA 20 and may be implemented by various different techniques. For instance, valve 28 may be actively controlled or check valve and opened to allow air within flux capacitor 29 to be expelled as fluid is injected into fluid chamber 22. In other examples, the vent 28 may be a bubble regulator and the pressure within the fluid reservoir 44 actively controlled to create a greater back-pressure prior to a filling cycle to withdraw air into the fluid reservoir 44 and create a vacuum within the flux capacitor 29. In either example or others, the result of a hyperinflation cycle is that the fluid chamber 22 in FAA 20 is refilled to a full level independent of its prior fluid level state. This refilling of the FAA 20 fluid chamber 22 ensures that the volume of the pressure regulation bag 42 in the fluid reservoir 44 is consistent and advancing for various retreating levels of fluid from the fluid reservoir 44 and without hysteresis which may be caused by changes in environmental conditions such as ambient air pressure and temperature. With pressure regulation bag 42 volumes set at the design phase and the top 62 of the fluid sensor 60 positioned accurately during manufacturing to match the nominal regulation point 48 of the pressure regulation bag 42, very accurate ink levels can be read in the accurate fluid level sensor reading range 63. Along with the hyperinflation cycle prior to reading, this process allows for rectification of variations in fill level, bag size, chamber size, etc. Accordingly, a more accurate gas gauge 70 fluid level detector allows fluid based systems and their users to better predict their fluid usage and thus saving large jobs and be better at planning expenditures for maintenance and refilling.

[0042] While the claimed subject matter has been particularly illustrated and described with reference to the foregoing examples, many variations may be made therein without departing from the intended scope of subject matter in the following claims. This description should be understood to include all novel and non-obvious combinations of elements described herein, and claims may be presented in this or a later application to any novel and non- obvious combination of these elements. The foregoing examples are illustrative, and no single feature or element is necessary to all possible combinations that may be claimed in this or a later application. Where the claims recite "a" or "a first" element of the equivalent thereof, such claims should be understood to include incorporation of such elements, neither requiring nor excluding two or more such elements.

Claims

What is claimed is: CLAIMS

1 . A system with a fluid level detector, comprising:

a fluid actuator assembly including a fluid chamber;

a fluid container, including:

a fluid reservoir coupled to the fluid chamber;

a pressure regulation bag disposed within the fluid reservoir; and a fluid level sensor to provide an estimate of a fluid level in the fluid reservoir and disposed such that when the fluid reservoir contains fluid, the fluid is not detected in contact with a top of the fluid level sensor once the pressure regulation bag is at a regulation point, and wherein when the pressure regulation bag is maximally inflated to fill the fluid chamber with the fluid, the estimate of the fluid level represents a measurement of an amount of fluid in the fluid reservoir once the pressure regulation bag returns to the regulation point.

2. The system of claim 1 , wherein the fluid reservoir is sized to allow fluid within the fluid reservoir to contact the top of the fluid level sensor when the fluid within the fluid reservoir is above a predetermined level.

3. The system of claim 1 , wherein the fluid level sensor is disposed substantially orthogonal to a gravitational bottom of the fluid reservoir and extends from the top of the fluid sensor to a fluid interface at the gravitational bottom of the fluid reservoir.

4. The system of claim 1 , further comprising a volume adjustment chamber to allow for different initial volumes of fluid to be stored in the fluid reservoir.

5. The system of claim 1 , further comprising:

an air pump; and

an air port coupled to the pressure regulation bag and the air pump wherein the air pump is to maximally inflate the pressure regulation bag.

6. The system of claim 1 , further comprising an electrical interface coupled to the fluid level sensor.

7. The system of claim 6, further comprising a memory coupled to the electrical interface to store the estimate of fluid level and a count of a number of drops representing an amount of fluid used by a fluid actuator assembly during a full level detected by the fluid level sensor.

8. The system of claim 7, wherein the full level is indicated by contact with fluid at the top of the fluid level sensor.

9. The system of claim 7, wherein the full level encompasses a volume of between about 85% and about 100% of the expected fluid capacity of the fluid container.

10. The system of claim 1 , wherein the fluid level sensor is selected from at least one of the group of temperature decay, timing, capacitance, inductance, resistance, reluctance, optical diffusion, optical interference, and optical timing.

1 1 . A non-transitory computer-readable medium, comprising instructions for a fluid level detector that when read and executed by a processor cause the processor to:

maximally inflate a pressure regulator bag disposed within a fluid reservoir of a fluid container containing fluid to fill a fluid chamber within a fluid actuator assembly, the fluid reservoir coupled to a fluid level sensor, wherein the fluid level sensor is disposed within the fluid reservoir such that fluid is not detected in contact with a top of the fluid level sensor once the pressure regulation bag is at a regulation point; and

read the fluid level sensor to provide an estimate of a fluid level in the fluid reservoir that represents a measurement of an amount of fluid in the fluid reservoir after the pressure regulator bag is maximally inflated and the pressure regulator bag returns to the regulation point.

12. The non-transitory computer-readable medium of claim 1 1 , further comprising instructions to:

detect that fluid within the fluid reservoir is in contact with a top of the fluid level sensor; and

count a number of drops of fluid used by a fluid actuator assembly coupled to the fluid container during a full level detected by the fluid level sensor.

13. The non-transitory computer-readable medium of claim 12, further comprising instructions to:

detect that fluid within the fluid reservoir is not in contact with the top of the fluid level sensor prior to reading the fluid level sensor to provide an estimate of the fluid level in the fluid reservoir.

14. The non-transitory computer-readable medium of claim 13, further comprising instructions to create a gas gauge using a combination of 1 ) the number of drops of fluid when the fluid within the fluid reservoir is detected in contact with the top of the fluid level sensor, and 2) an output of the fluid level sensor when the fluid within the fluid reservoir is not detected in contact with the top of the fluid level sensor.

15. The non-transitory computer readable medium of claim 1 1 , further comprising instructions to:

read the contents of a memory on the fluid container to determine a model of the fluid container; and

set a maximum fluid level based on the determined model of the fluid container.