ULTRASOUND INSPECTION CALIBRATION USING A TARGET

Examples of the present subject matter provide a calibration technique to configure inspection parameters directly on an object. The calibration technique may include a target device configured to be placed on a testing surface of an object for calibration. The target device may reflect acoustic waves transmitted from a transducer probe. The reflected acoustic waves may then be used for determining one or more characteristics of the object.

TECHNICAL FIELD

The present disclosure generally relates to calibration of ultrasound inspection components.

BACKGROUND

Calibration of acoustic inspection system elements can involve a complex process and can consume a significant amount of time. In some instances, calibration blocks are used to calibrate inspection components, such as for performing an amplitude calibration. For example, an acoustic transducer probe that is going to be used for inspection can be acoustically coupled to a calibration block for calibration. The calibration block can be a metal block and can include drilled holes, such as to emulate standard flaws or otherwise provide features emulating flaws in known locations. For calibration, the transducer probe may perform inspection of the calibration block. Based on the known properties of the calibration blocks, e.g., holes emulating flaws, aspects of the acoustic inspection system may be calibrated such as relating to the transducer probe or to other elements in the inspection signal chain.

Generally, after calibration, the transducer probe is acoustically decoupled from the calibration block and then acoustically coupled to the object for inspection (e.g., object-under-test). Thus, the calibration performed on the separate calibration block may not be accurate for the object. For example, the object and the calibration block can have different properties, surface roughness, acoustic impedances, and mechanical coupling configurations, etc. Assumptions may be made by the operator to compensate for such differences. However, if such assumptions made in calibration are inaccurate or incomplete, they can adversely impact the testing results.

DETAILED DESCRIPTION

The inventors have recognized a need in the art for a calibration technique that, among other things, overcomes the drawbacks discussed above. Examples of the present subject matter can provide a calibration technique to determine inspection parameters for use in evaluating an object, such as using a propagation path including the object. For example, the calibration technique may include a target device (e.g., a calibration target assembly) configured to be placed on a surface of an object for calibration. The surface can be the same surface as is used for mechanically coupling an acoustic transducer probe to the object. In another example, the target device and acoustic transducer probe may be placed on different surfaces (e.g., opposing surfaces of an object). The target device may reflect acoustic waves transmitted from a transducer probe. The reflected acoustic waves may then be used for determining one or more characteristics of the object. Hence, the calibration is performed while the transducer probe is coupled to the object, leading to more accurate results at least in part because the propagation characteristics and related constitutive parameters of the object are factored into the calibration technique.

This document describes an inspection system. The inspection system may include a transducer probe configured to transmit an acoustic wave from a first location on an object. The inspection system may also include a target configured to reflect the transmitted acoustic wave from a second location on the object to produce a reflection of the acoustic wave. The inspection system may further include a control circuit configured to receive information about the reflection of the acoustic wave for determination of at least one characteristic relating to the object.

This document also describes a method comprising: placing a transducer probe at a first location on a surface of an object; placing a target at a second location on the surface of the object; transmitting an acoustic wave from the transducer probe into the object to the target; receiving the acoustic wave; and based on measurements of the received acoustic wave, simultaneously determining a plurality of characteristics relating to the object.

This document further describes an inspection system including a first transducer probe configured to transmit an acoustic wave into an object from a first location on the object and a second transducer probe configured to receive the acoustic wave from a second location on the object using a transducer element having a size approximately λ/2, where λ is a wavelength of the acoustic wave. The inspection system may also include a control circuit configured to receive information about the received acoustic wave and to simultaneously determine a plurality of characteristics relating to the object.

FIG. 1illustrates a target device100, according to an example of the present subject matter. The target device100may include targets102,104and a target holder106. As described in further detail below, the target device100may be used for calibration of a transducer probe to configure inspection parameters derived directly from an object to be tested. The targets102,104may be made of a material having a relatively high acoustic impedance compared to free space. For example, the targets102,104may be made of the same or similar material as an object, such as comprising a metal. For example, the targets102,104may be provided as metallic structures protruding from the target holder106. The targets102,104may be provided using a material with an acoustic impedance that substantially matches an acoustic impedance of the object. The width and height (e.g., size) of the targets102,104may be set to approximately to λ/2, where λ is a wavelength of an acoustic wave within the target material (object) to be used with the target device100, as described in further detail below. The targets102,104may be spaced apart by a distance “d.” The gap between the targets can be free space or a material having acoustic characteristics contrasting with the targets102,104, such as similar to the target holder material106. Two targets are shown inFIG. 1for illustration purposes; one target or more than two targets may be provided with the target device.

The target holder106may be made of a material of relatively lower acoustic impedance as compared to the targets102,104. For example, the target holder106may be a polymer material. Because the target holder106may be of relatively lower impedance than the targets102,104, the target holder106may insulate the targets102,104. That is, acoustic waves traversing the targets102,104may not propagate into the target holder106. Instead, the acoustic waves may diffract, scatter, and then reflect from inside the targets102,104. In this manner, the targets102,104may imitate a flaw in the object.

FIG. 2illustrates an inspection system200according to an example of the present subject matter. The inspection system200may include a target device100(as described above) and an inspection device202with a transducer probe204(e.g., comprising an array of electroacoustic transducers) and a wedge206.

The inspection device may generate, transmit, and receive acoustic waves as described herein.FIG. 3illustrates generally an example comprising an inspection system300in which inspection device202may operate, such as can be used to perform one or more techniques showed and described elsewhere herein. The inspection system300may include a test instrument340, such as a hand-held or portable assembly. The test instrument340may be electrically coupled to a probe assembly, such as using a multi-conductor interconnect330. The probe assembly350may include one or more electroacoustic transducers, such as a transducer array352including respective transducers354A through354N. The transducers array may follow a linear or curved contour, or may include an array of elements extending in two axes, such as providing a matrix of transducer elements. The elements need not be square in footprint or arranged along a straight-line axis. Element size and pitch may be varied according to the inspection application.

A modular probe assembly350configuration may be used, such as to allow a test instrument340to be used with different types of probe assemblies350. Generally, the transducer array352includes piezoelectric transducers, such as can be acoustically coupled to a object210(e.g., an object under test) through a coupling medium356. The coupling medium can include a fluid or gel or a solid membrane (e.g., an elastomer or other polymer material), or a combination of fluid, gel, or solid structures. For example, an acoustic transducer assembly can include a transducer array coupled to a wedge structure comprising a rigid thermoset polymer having known acoustic propagation characteristics (for example, Rexolite® available from C-Lec Plastics Inc.), and water can be injected between the wedge and the structure under test as a coupling medium356during testing.

The test instrument340can include digital and analog circuitry, such as a front-end circuit322including one or more transmit signal chains, receive signal chains, or switching circuitry (e.g., transmit/receive switching circuitry). The transmit signal chain can include amplifier and filter circuitry, such as to provide transmit pulses for delivery through an interconnect330to a probe assembly350for insonification of the target358, such as to measure one or more characteristics of the object358such as for determining a dimension of a object (e.g., a thickness) or a location or existence of a flaw on or within the object based on receiving scattered or reflected acoustic energy elicited in response to the insonification, e.g., echoes.

WhileFIG. 3shows a single probe assembly350and a single transducer array352, other configurations may be used, such as multiple probe assemblies connected to a single test instrument340, or multiple transducer arrays used with a single or multiple probe assemblies350for tandem inspection. Similarly, a test protocol can be performed using coordination between multiple test instruments340, such as in response to an overall test scheme established from a master test instrument340, or established by another remote system such as a compute facility308or general purpose computing device such as a laptop332, tablet, smart-phone, desktop computer, or the like. The test scheme may be established according to a published standard or regulatory requirement and may be performed upon initial fabrication or on a recurring basis for ongoing surveillance, as illustrative examples.

The receive signal chain of the front-end circuit322can include one or more filters or amplifier circuits, along with an analog-to-digital conversion facility, such as to digitize echo signals received using the probe assembly350. Digitization can be performed coherently, such as to provide multiple channels of digitized data aligned or referenced to each other in time or phase.

Returning toFIG. 2, the inspection device202and the target device100may be placed on a surface of an object210. For calibration, the inspection device202may be placed at a first location on the surface of the object210. The target device100may be placed on the surface of the object210so that the first target102is located at a second location and the target104is located at a third location. A coupling material212may be provided in between the surface of the object210and the targets102,104. For example, the coupling material may include a fluid or gel. The type of coupling material212may be selected based on the testing environment. In an example, the coupling material212may be water-based. In another example (e.g., a cold testing environment), the coupling material212may be alcohol-based. The coupling material may also be chosen based on the testing method. For example, testing using longitudinal (L) waves may use a first family of couplants while testing using shear or transverse waves may use a second family of couplants.

In another example, the inspection device202and the target device100may be placed on different surfaces of the object210. For example, they may be placed on opposing surfaces of the object210. That is, the inspection device202may be placed at a first location on a first surface of the object210, and the target device210may be placed on a second surface of the objection210where the target devices so that the first target102is located at a second location on the second surface and the target104is located at a third location on the second surface.

FIG. 4is a flow diagram of a calibration method400, according to an example of the present subject matter. Method400may be performed by the inspection system200described above. At402, an inspection device with a transducer probe (e.g.,202as shown inFIG. 2) may be placed at a first location on a surface of an object. At404, a first target (e.g.,102as shown inFIG. 2) may be placed at a second location on the surface of the object. The inspection device and the first target may be spaced apart by a distance L. As discussed above, in another example, the inspection device and the first target may be placed on different surfaces of the object. At406, an acoustic wave may be transmitted by the transducer probe into the object. In the example ofFIG. 2, the acoustic wave may travel along a propagation path through the object including reflecting or scattering off a surface opposite the transducer probe (e.g., backwall), to reach the first target, including traversing a vertical thickness, “H” defined by the object. The acoustic wave may then be reflected or scattered by the target, with reflected or scattered acoustic energy traveling back through the object as shown by the dotted-and-dashed-lines inFIG. 2. Referring toFIG. 4, at408, the transducer probe may receive the reflected acoustic wave. In an example, a first transducer element of the transducer probe may transmit the acoustic wave and a second (e.g., different) transducer element of the transducer probe may receive the reflected acoustic wave.

At410, the method400may check if one or two targets are being used. If only one target is to be used, a control circuit, at412, may take information relating to and from the received acoustic wave (e.g., time of travel) and determine one or more characteristics relating to the object. The characteristics may include absorption per length, velocity, amplitude, thickness, a geometrical characteristic, and/or sensitivity. For example, if a distance between the inspection device and the target (L) and the thickness of the object (H) is known, then an acoustic propagation velocity (e.g., a group velocity) in the object may be determined based on the time-of-travel of the acoustic wave.

In an example, the control circuit may input information relating to the received acoustic wave into a calibration model or map. Based on the model or map, different parameters of the object may be calculated. With the use of a model, parameters for other configurations may also be calculated. For example, if the inspection aim is for an one inch thick material, the model may set the inspection device for a setting to detect a defect or flaw for an one inch thick material based on the one or more characteristics calculated during calibration; the setting may include, for example, automatic gain control and compensation matching.

At414, if more than one target is to be used, a second target (e.g.,104) may be placed at a third location on the surface of the object. The inspection device and the first target may be spaced apart by a distance L and the first and second targets may be space apart by a distance d, so the inspection device and the second target may be spaced apart by a distance L+d. At414, a second acoustic wave may be transmitted by the transducer probe into the object. In the example ofFIG. 2, the second acoustic wave may travel along a propagation path through the object including reflecting or scattering off a surface opposite the transducer probe (e.g., backwall), to reach the second target, including traversing a vertical thickness, “H” defined by the object. The acoustic wave may then be reflected or scattered by the second target, with reflected or scattered acoustic energy traveling back through the object as shown by the dotted-and-dashed-lines inFIG. 2. Referring toFIG. 4, at416, the transducer probe may receive the second reflected acoustic wave. In an example, a first transducer element of the transducer probe may transmit the first and second acoustic waves and a second transducer element of the transducer probe may receive the reflected first and second acoustic waves from the first and second targets, respectively.

At410, the control circuit may take the information from the received acoustic waves from the first and second targets and determine one or more characteristics relating to the object. The characteristics may include absorption per length, velocity, amplitude, thickness, a geometrical characteristic, and/or sensitivity. In an example, H may not be known a priori. Using multiple targets, say two, and assuming constant velocity (a first unknown variable) and constant thickness H (a second unknown variable), the control circuit may calculate estimates of H and velocity based on the time of flight and other known properties (e.g., distance of the targets). Using more targets may provide further insight into the geometry of the object (e.g., slope of the backwall), or provide “over determination” data for measurement uncertainty, for example.

As discussed above, the control circuit may also input information relating to the received acoustic waves into a calibration model or map. Based on the model or map, different parameters of the object may be calculated. With the use of a model, parameters for other configurations may also be calculated.

For example, one technique of using a target device, as described herein, to evaluate the numeric value of some physical parameters of the object may involve building a system of equations, including at least as many observations as there are unknowns in the system. Thus, a plurality of physical parameters may be determined simultaneously.FIG. 5(A)illustrates a technique for calculating a parameter of an object according to an example of the present subject matter. Here, the sound speed of a P-wave and a thickness of the object may be calculated using a target device, as described herein. InFIG. 5(A), two targets are depicted. Echoes from the two targets using two transducer elements may be collected; the two transducer elements may be fired individually as shown. The echoes may be identified based on their pairing. InFIG. 5(A), the transducer elements are labeled n and n′, and the targets are labeled a and a′.

FIG. 5(B)illustrates a time series of acquisition combination according to an example of the present subject matter. The echoes may come in a pair using the two targets in this example. Three time-series acquisitions may be used: (i) the detected signal from first element n to first element n; (ii) the detected signal from element n to second element n′; and (iii) the detected signal from second element n′ to second element n′. Thus, a total of six time-values for the position of echoes may be found.

A model for the time of flight may be drawn based on assumptions about the propagation material (e.g., material is linear isotropic and homogenous, and the object is a constant thickness). Hence, the total time of flight may include a going segment and a returning segment:

Moreover, each segment may be cast as a path segment in the wedge and second path segment in the object to inspect:

FIG. 5(C)illustrates the terms used in the above equations. Here, the distance to the target (Lα) may be a known parameter, as well as other parameters except the sound speed CBPand the object thickness H as well as the four incidence angles at the object surface. Six equations for the six different time of flights to the six observations may be assembled. For these six equations, the sound speed CBPand the object thickness H may be simultaneously calculated. The following table may summarize the known/observed quantities and the set of unknowns to be evaluated:

Different approaches may be used, including a simplex method, a gradient method, and/or a Newton-Raphson method. Additional targets (also having other sets of transmitting and receiving elements) may be used to build an overdetermined system of equations. Moreover, the example here is for obtaining estimates for the P-wave sound seed and the object thickness using a data set from a PP-PP round trip, but this concept may also be performed for S-wave sound speed using a SS-SS round trip.

Another parameter of interest may be the acoustic propagation loss factor, which may be linked to material scattering and thermal losses. For example, the acoustic propagation loss factor may affect the level of gain to add to the received signal to equalize its value through some region of interest in the object. The acoustic propagation loss may be modeled as a linear loss with propagation distance (e.g., exponential decay of the amplitude), which may be different from the geometric attenuation associated with the expansion from a finite size source as it may be intrinsic to the material and can be measured empirically.

FIG. 6(A)illustrates a technique for calculating an acoustic propagation loss parameter of an object according to an example of the present subject matter.FIG. 6(B)illustrates exemplary signals from the targets observed at the receiver element. One technique to evaluate the acoustic propagation loss factor is with the use of an acoustic model for the response amplitude A(t) from a flaw in the object. Such a model may be based on the superposition of the contribution from multiple elements amplitude (Ann′(t)) to the received signal:

The loss factor may be introduced in the model from the path in the part from one transmitting element to a receiving element:

An acquisition scheme that produces sufficient data to evaluate a is based on the projection of beams in transmission and reception on the targets. Other propagation parameters may be known to produce physical beams that correspond to model beams.FIGS. 6(C) and 6(D)show initial and optimal models. The solution to determine the acoustic propagation loss factor may be based on the computation of a lossless model amplitude response from element n to another element n′, as the loss factor α is varied until the difference between the observed time traces and the model time traces become minimal. Because the optimization process may be affected by the signal phase, which would often be considered another variable to optimize, signal enveloping technique may be used (instead of the RF signal). Once the optimal loss factor (α=α′) is found, it may be used in the model to produce a compensation map that is effective in the region of interest.

The above examples depicted an object with a defined or known thickness. The calibration techniques described herein may also be applied for objects whose thickness is unknown to use reflections off a backwall.FIG. 7illustrates an inspection system700, according to an example of the present subject matter. The inspection system700may include an inspection device702with a transducer probe704and a wedge706, and the inspection system700may also include a target device710. The inspection device702may be provided as described above with reference toFIG. 2and/orFIG. 3.

The target device710may include a target712and a target holder714. As described herein, the target device710may be used for calibration of a transducer probe to configure inspection parameters directly on the object to be tested. The target712may be made of a material of relatively high acoustic impedance. The target712may operate as surface wave breaker. For example, the target712may be made of the same or similar metal as an object720. The target may be provided as a shard of metal. The target712may be provided with a material with an acoustic impedance that substantially matches an acoustic impedance of the object720.

Here, the object720may be a thick/deep part or where the backwall geometry may non-uniform. Thus, using reflections of the backwall of the object720may not be effective. The inspection device702may use surface wave(s) for calibration, as described in further detail below.

The inspection device702and the target device710may be placed on a surface of an object720. For calibration, the inspection device702may be placed at a first location on the surface. The target device710may be placed on the surface so that the closest corner of the target702to the inspection device702is located at a second location. A coupling material722may be provided in between the surface of the object720and the712. For example, the coupling material may include a fluid or gel. The type of coupling material722may be selected based on the testing environment. In an example, the coupling material722may be water-based. In another example (e.g., a cold testing environment), the coupling material722may be alcohol-based. The coupling material may also be chosen based on the testing method.

FIG. 8is a flow diagram of a calibration method800using surface wave(s), according to an example of the present subject matter. Method800may be performed by the inspection system700described above with reference toFIG. 7. At802, an inspection device with a transducer probe (e.g.,702ofFIG. 7) may be placed at a first location on a surface of an object. At804, a target (e.g.,722ofFIG. 7) may be placed at a second location on the surface of the object. The inspection device and the closest corner of the target may be spaced apart by a distance L.

At806, surface wave(s) may be transmitted by the transducer probe onto the surface of the object. The surface wave is a type of acoustic wave and may include a mixture of P-waves and Rayleigh waves, where the P-waves are P-polarized (vibrations parallel to the propagation direction) and the Rayleigh waves are a mixture of P- and S-polarizations (elliptical vibrations). The P-waves propagating in the surface wave, also known as lateral waves, may have the same velocity as bulk P-waves propagating in the volume of the object. In the present disclosure, use of the term “P-wave” will include both surface P-waves and bulk P-waves.

The critical angle for a P-wave may be different from the critical angle for a Rayleigh wave. The P-waves have an acoustic velocity VP, and the Rayleigh waves have an acoustic velocity VR which is known to be linked to the velocities of both P- and S-waves (VPand VS) in the object according to the following equation, which is well-known in the art (see for example, Jr. Lester W. Schmerr, Fundamentals of Ultrasonic Nondestructive Evaluation—A Modeling Approach, Plenum Press, 1998):

The surface wave may crawl on the surface of the object, reach the target (in particular, the corner of the target), and reflect back towards the transducer probe. At808, the transducer probe may receive the reflected surface wave(s).

At810, a control circuit may take the information from the received surface wave (e.g., time of flight) and determine one or more characteristics relating to the object. The characteristics may include absorption per length, velocity, amplitude, thickness, a geometrical characteristic, and/or sensitivity. The control circuit may use a calibration model or map, as described herein.

Moreover, the target devices described herein may be used during inspection, too. Keeping the target device on the object may allow instant calibration as the inspection device moves along the object-under test. This may be particularly beneficial for an object with non-uniform properties, for example a part with bumps or the like. Thus, using the techniques described herein, characteristics of different locations or instants may be gathered along a scanning axis.

Indeed, the monitoring techniques described herein may be used to calculate non-homogenous velocity patterns in objects. For example, by using multiple targets at known distances, velocity at different parts of the object may be determined. Velocity can change at different locations and angles of an object.

FIG. 9illustrates an inspection system900with two probes, according to an example of the present subject matter. The inspection system900may include a first and a second inspection device902,912. Each of the inspection devices may include a transducer probe904,914and a wedge906,916. Here, the second inspection device912is in place of the target device described in the above examples. The inspection devices902,912may be provided as described above with reference toFIGS. 2 and/or 3.

Here, the first inspection device902may transmit acoustic wave(s) into or on the surface of the object, as described above with reference toFIGS. 2-6. For example, a first transducer element in the first inspection device902may transmit a first wave, and a second transducer element in the first inspection device902may transmit a second wave. A transducer element in the second inspection device912may receive the acoustic wave. The size (e.g., width) of the receiving transducer element may be set to approximately to λ/2, where λ is a wavelength of the acoustic wave in the target material. A control circuit may take the information from the received acoustic wave (e.g., time of travel) and determine one or more characteristics relating to the object. The characteristics may include absorption per length, velocity, amplitude, thickness, a geometrical characteristic, and/or sensitivity. The control circuit may use a calibration model or map, as described herein.

In addition to determining characteristics of the object, the techniques described herein may be applied for determining properties of the inspection device itself, namely the wedge.FIG. 10illustrates an inspection system1000, according to an example of the present subject matter. The inspection system1000may include an inspection device1002with a transducer probe1004and a wedge1006, and the inspection system1000may also include a target device100with targets102,104and target holder106. The target device100may be provided as described herein (e.g., target device100ofFIGS. 1-2).

Here, the target device100may be coupled to the inspection device1002as shown. The targets102,104may be coupled to the wedge1006. The inspection device1002may transmit one or more acoustic waves, which may reflect off the targets102,104. The reflected acoustic waves may then be received by the inspection device1001. For example, a first transducer element in the inspection device1002may transmit first and second acoustic waves, and a second transducer element in the inspection device1002may receive the reflected first and second acoustic waves from the targets102,104, respectively. A control circuit may take the information from the received acoustic wave (e.g., time of travel) and determine one or more characteristics relating to the wedge. The characteristics may include absorption per length, velocity, amplitude, thickness, a geometrical characteristic, and/or sensitivity. In an example, characteristic of the wedges may be obtained in a first step and then characteristics of the object may be obtained in a second step using the techniques described herein. Hence, the obtained characteristics of the object in the second step may be more accurate because any variances in the wedge may be accounted for in the first step.

Examples, as described herein, may include, or may operate by, logic or a number of components, or mechanisms. Circuitry is a collection of circuits implemented in tangible entities that include hardware (e.g., simple circuits, gates, logic, etc.). Circuitry membership may be flexible over time and underlying hardware variability. Circuitries include members that may, alone or in combination, perform specified operations when operating. In an example, hardware of the circuitry may be immutably designed to carry out a specific operation (e.g., hardwired). In an example, the hardware comprising the circuitry may include variably connected physical components (e.g., execution units, transistors, simple circuits, etc.) including a computer readable medium physically modified (e.g., magnetically, electrically, such as via a change in physical state or transformation of another physical characteristic, etc.) to encode instructions of the specific operation. In connecting the physical components, the underlying electrical properties of a hardware constituent may be changed, for example, from an insulating characteristic to a conductive characteristic or vice versa. The instructions enable embedded hardware (e.g., the execution units or a loading mechanism) to create members of the circuitry in hardware via the variable connections to carry out portions of the specific operation when in operation. Accordingly, the computer readable medium is communicatively coupled to the other components of the circuitry when the device is operating. In an example, any of the physical components may be used in more than one member of more than one circuitry. For example, under operation, execution units may be used in a first circuit of a first circuitry at one point in time and reused by a second circuit in the first circuitry, or by a third circuit in a second circuitry at a different time.

Machine (e.g., computer system)1100may include a hardware processor1102(e.g., a central processing unit (CPU), a graphics processing unit (GPU), a hardware processor core, or any combination thereof), a main memory1104and a static memory1106, some or all of which may communicate with each other via an interlink (e.g., bus)1108. The machine1100may further include a display unit1110, an alphanumeric input device1112(e.g., a keyboard), and a user interface (UI) navigation device1114(e.g., a mouse). In an example, the display unit1110, input device1112and UI navigation device1114may be a touch screen display. The machine1100may additionally include a storage device (e.g., drive unit)1116, a signal generation device1118(e.g., a speaker), a network interface device1120, and one or more sensors1121, such as a global positioning system (GPS) sensor, compass, accelerometer, or other sensor. The machine1100may include an output controller1128, such as a serial (e.g., universal serial bus (USB), parallel, or other wired or wireless (e.g., infrared (IR), near field communication (NFC), etc.) connection to communicate or control one or more peripheral devices (e.g., a printer, card reader, etc.).

The storage device1116may include a machine readable medium1122on which is stored one or more sets of data structures or instructions1124(e.g., software) embodying or utilized by any one or more of the techniques or functions described herein. The instructions1124may also reside, completely or at least partially, within the main memory1104, within static memory1106, or within the hardware processor1102during execution thereof by the machine1100. In an example, one or any combination of the hardware processor1102, the main memory1104, the static memory1106, or the storage device1116may constitute machine readable media.

Various Notes

Each of the non-limiting aspects above can stand on its own or can be combined in various permutations or combinations with one or more of the other aspects or other subject matter described in this document.