Circuit, device, and method to measure biosignal using common mode driven shield

An apparatus and method of removing common mode noise in the case of measuring a biosignal using a capacitive coupling active electrode (CCE) is provided. A frequency band of a common mode signal may interact with a shield voltage and thus, a frequency band of a biosignal may be compensated for.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit under 35 U.S.C. § 119(a) of Korean Patent Application No. 10-2013-0094166, filed on Aug. 8, 2013, in the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference for all purposes.

BACKGROUND

The following description relates to a biosignal measuring apparatus and a biosignal measuring method.

2. Description of Related Art

In cases where an object, such as clothes, for example, having a great electrical resistance is present between a human body and a ground of a measurement device, an indirect contact (IDC) biosignal measurement device may need to decrease common mode noise such as power noise, for example.

To decrease the common mode noise, the IDC biosignal measurement device may be designed to minimize impedance between the human body and the ground. To this end, electrical impedance between the human body and the ground may be minimized by increasing the electrical capacity between the human body and the ground by employing a maximally wide ground plate. Equivalent impedance between the human body and the ground may be decreased using a method called a right-leg-driven (RLD) ground method, an active ground method, or an active common method. In the case of using the RLD ground method, a size of the ground plate may be further reduced.

SUMMARY

In one general aspect, there is provided a capacitive coupling active electrode (CCE) circuit including an electrode face configured to sense a biosignal; a common mode interacting unit configured to enable a common mode signal to interact with a shield voltage in order to compensate for a frequency band; and a shield configured to provide the shield voltage.

The CCE circuit may further include a preamplifier configured to amplify the shield voltage and the biosignal, wherein the shield may be further configured to provide the shield voltage to the pre-amplifier.

The common mode interacting unit may include a filter configured to enable a signal of the frequency band in the common mode signal to pass.

The filter may include a capacitor, a resistance, and a passive element that are configured to enable the signal of the frequency band to pass at a gain.

The common mode interacting unit may include a frequency band changing unit configured to change a frequency band of the common mode signal for compensating for the biosignal according to a control of a user.

The common mode interacting unit may include a driven gain applying unit configured to enable the common mode signal to interact with the shield voltage by applying a common mode driven gain to the common mode signal at a ratio of input impedance to a sum of input impedance and shield impedance.

The common mode interacting unit may include an adjusting unit configured to adjust a gain and a phase of the common mode signal to correspond to a common mode driven gain.

The common mode interacting unit may include at least one of a low band pass (LBP) filter and a high band pass (HBP) filter through which the common mode signal passes.

In another general aspect, there is provided a device for measuring a biosignal, the device including a common mode interacting unit configured to feed back a common mode signal to a shield for compensating for a frequency band; a capacitive coupling active electrode (CCE) comprising an electrode face configured to measure the biosignal and the shield connected to the common mode interacting unit; and a differential amplifier configured to amplify a differential component of the biosignal measured by the CCE.

The device may further include a pre-amplifier disposed at a rear of the electrode face, wherein the shield may surround the electrode face and the pre-amplifier.

The common mode interacting unit may include a filter configured to enable a signal of the frequency band in the common mode signal to pass.

The filter may include a capacitor, a resistance, and a passive element that are configured to enable the signal of the frequency band to pass at a gain.

The common mode interacting unit may include a frequency band changing unit configured to change a frequency band of the common mode signal for compensating for the biosignal according to a control of a user.

The common mode interacting unit may include a driven gain applying unit configured to enable the common mode signal to interact with the shield voltage by applying a common mode driven gain to the common mode signal at a ratio of the input impedance to a sum of input impedance and shield impedance.

The common mode interacting unit may include an adjusting unit configured to adjust a gain and a phase of the common mode signal to correspond to a common mode driven gain.

The common mode interacting unit may include at least one of a low band pass (LBP) filter and a high band pass (HBP) filter through which the common mode signal passes.

In another general aspect, there is provided a method for measuring a biosignal, the method including sensing the biosignal; enabling a common mode signal to interact with a shield voltage in order to compensate for a frequency band; feeding back the shield voltage to the biosignal; and amplifying a differential component of the biosignal to which the shield voltage is fed back.

The enabling may include enabling a signal of the frequency band in the common mode signal to pass.

The enabling may include changing a frequency band of the common mode signal for compensating of the biosignal according to a control of a user.

The enabling may include enabling the common mode signal to interact with the shield voltage by applying a common mode driven gain to the common mode signal at a ratio of input impedance to a sum of input impedance and shield impedance.

The enabling may include adjusting a gain and a phase of the common mode signal to correspond to a common mode driven gain.

In another general aspect, there is provided an electrode circuit for sensing a biosignal, the electrode circuit including an interacting unit configured to enable a common mode signal to interact with a shield voltage in order to compensate for a frequency band; and a filter configured to enable a signal of the frequency band in the common mode signal to pass.

DETAILED DESCRIPTION

FIG. 1illustrates an example of an electrical configuration of an indirect contact (IDC) biosignal measurement device. The IDC biosignal measurement device may include an indirect contact electrocardiogram (IDC-ECG) measurement device. For example, IDC-ECG may refer to a measurement technology of measuring ECG on clothes without direct contact between the electrode and the human body190. The IDC-ECG may include a capacitive coupling active electrode (CCE)110having a high input resistance, and a ground plate made of wide conductive fabric.

The CCE110may generate capacitive coupling between the skin and the electrode by indirectly contacting the skin of the human body190through clothes. A differential component may be extracted from each of two signals measured from two active electrodes using a differential amplifier120. In this example, an ECG waveform is obtained by amplifying and filtering the differential component using an amplifier and a filter130. A ground plate may ground the human body190based on capacitive coupling through clothes, without directly contacting the skin of the human body190. For example, even though the human body190and measurement equipment do not directly contact each other, a biosignal may be measured using the CCE110and an IDC ground plate.

FIG. 2illustrates an example of a CCE. Referring toFIG. 2, the CCE may include an electrode face211provided as a metal plate, a pre-amplifier213disposed at the rear of the electrode face211, and a metal shield212configured to surround the electrode face211and a rear surface of the electrode face211. In a case in which clothes291are present between the electrode face211and the human body290, capacitive coupling such as CCLTHmay be generated.

In various aspects, resistance RBmay be connected between a ground and an input terminal of the pre-amplifier213in order to stabilize an amplifier by flowing bias current in an amplifier element, for example, a transistor or an operation amplifier included in the pre-amplifier213. In an example of measuring a biosignal using an indirect contact, high resistance, a resistance of 2G Ω or more may be used to increase input impedance of the amplifier. Here, stray capacitance CBmay be present between the electrode face211and the ground.

FIG. 3illustrates an example of an electrical model of a CCE310. Referring toFIG. 3, ESdenotes a signal source, that is, a biosignal generator in the case of measuring a biosignal, and ZEdenotes impedance of clothes391present between the electrode and the skin of a human body. Input impedance ZAof a pre-amplifier313may be modeled as a capacitor CAand a resistance RA. The impedance ZEof the clothes391may be modeled as a capacitor CCLTHand a resistance RCLTH. Input voltage of the pre-amplifier313may be expressed as VINand output voltage of the pre-amplifier313may be expressed as VO.

To remove common mode noise in the CCE310, a differential measurement method using two electrode signals may be employed to measure a biosignal using an indirect contact method together with a general biosignal measurement method. In this example, even though the differential measurement method is used, the common mode noise may not be completely removed. For example, a common mode rejection ratio (CMRR) of the pre-amplifier313may be limited. A portion of common mode voltage may be switched to a differential mode voltage due to a difference in impedance between two electrodes. Thus, the common mode noise may not be completely removed. Here, due to a characteristic of indirect contact through the clothes391, power noise by the impedance difference of the clothes391between two electrodes may be great in the case of measuring a biosignal using the indirect contact method.

For example, in an IDC biosignal measurement system, a shield may be connected to a ground of an IDC biosignal measurement device and the resistance RBconnected to the shield may also be connected to the ground. Such shielding method will be referred to as a grounded shield.

To decrease common mode noise, a common mode driven shield may vary a shield voltage during interaction with a common mode input voltage. An operation of the common mode driven shield will be described below.

FIG. 4illustrates an example of an IDC biosignal measurement device to which a unit gain common mode driven shield is applied. Referring toFIG. 4, a human body490may be modeled as a signal source ES, common mode noise between the human body490and the air may be modeled as impedance ZNand a signal source ECM, and a relationship between the human body490and a ground may be modeled as impedance ZG.

InFIG. 4, a common mode noise component based on a ground shield, for example, a shield voltage VSHIELD=0, may be expressed as follows. In a case in which impedance of two electrodes is identical to impedance of clothes with respect to the two electrodes, a differential component observed at an input end of a differential amplifier420may be expressed as the following Equation 1. In this example, the common mode noise component is absent in Equation 1. The impedance of clothes may differ as follows.

For example, in a case in which the impedance of clothes with respect to one of two electrodes varies from ZEto ZE+ΔZE, the differential component of the input end of the differential amplifier420may be approximated to the following Equation 2. In this example, ZE>>ΔZEis applied. Equation 2 may express a differential component by a common mode voltage source ECM, and a magnitude of the aforementioned differential component may be in proportion to a difference ΔZEin clothes impedance between two electrodes. The common mode voltage source ECMmay refer to a signal source

Each of V1and V2denotes an output obtained when a biosignal interacting with the shield voltage passes through a pre-amplifier and has a unit of “V”. The average of V1and V2may be used as a common mode signal and a difference between V1and V2may be used as a differential component. ESdenotes a signal source obtained by modeling a biosignal of the human body490, and has a unit of “V”. ZBdenotes shield impedance formed between an electrode and a shield and has a unit of ohm, and ZEdenotes the impedance of clothes and has a unit of ohm. ZGdenotes impedance between the human body490and the ground and has a unit of ohm, and ZNdenotes modeled impedance between the human body490and the air and has a unit of ohm. ECMdenotes a signal source obtained by modeling the common mode noise between the human body490and the air and has a unit of “V”.

In various aspects,FIG. 4illustrates an example of an IDC biosignal measurement device to which a unit-gain common mode driven shield is applied. In this example, as given by Equation 3 below, the shield voltage VSHIELDmay interact as the average voltage between two outputs of two electrodes. The average voltage between two outputs may be expressed as a common mode voltage signal that is approximately applied in common to two electrodes.
VSHIELD=(V1+V2)/2  [Equation 3]

For example, referring toFIG. 4, the common mode voltage may have a gain of “1” and may be connected to the shield through a common mode interacting unit441. Accordingly, input impedance of an electrode may be increased equivalently with respect to a common mode component. Thus, common mode noise may be decreased by the asymmetry of the impedance ZEof clothes.

According to various aspects, the unit gain common mode driven shield may decrease common mode noise by equivalently increasing the input impedance of the electrode. Compared to a case of measuring a biosignal using an existing different electrode, in the case of measuring a biosignal using a CCE410, a relatively small effect may be achieved since the shield impedance ZBofFIG. 3is relatively great. Specifically, the input impedance ZAof the operation amplifier may be relatively decreased compared to the shield impedance ZB. For example, in the case of applying the unit-gain common mode driven shield to measure a biosignal using the CCE410, the shield impedance ZBequivalently increases, but the input impedance ZAconnected in parallel thereto is maintained without being increased. Accordingly, an increase in the equivalent input impedance with respect to the entire electrode common mode component may decrease.

FIG. 5illustrates an example of a device for measuring a biosignal using a common mode driven shield. Referring toFIG. 5, a human body590, a CCE510, and a differential amplifier520may be similar to the human body490, the CCE410, and the differential amplifier420ofFIG. 4.

A common mode driven shield of an input impedance compensation type according to various examples may determine a common mode driven gain to maximize input impedance of an electrode with respect to a common mode component using a common mode interacting unit540. A shield voltage VSHIELDmay interact with a common mode signal using the common mode interacting unit540according to Equation 4 below.
VSHIELD=GSH(V1−V2)/2  [Equation 4]

In Equation 4, an optimal common mode driven gain GSHmay be expressed as in Equation 5 below.

The CCE510may include an electrode face, the common mode interacting unit540, a shield, and a pre-amplifier.

The electrode face may sense a biosignal through the impedance of clothes as modeled by ZE.

The common mode interacting unit540enables the common mode signal to interact with the shield voltage in order to compensate for a predetermined frequency band. Here, the predetermined frequency band may include a frequency band determined to decrease common mode noise. For example, the predetermined frequency band may include a frequency band in which noise desired to be removed by a user occurs or a frequency band in which power noise occurs, such as a frequency band of 60 Hz.

The common mode interacting unit540may include a filter configured to enable a signal of the predetermined frequency band in the common mode signal to pass. For example, the filter may include a capacitor, a resistance, and a passive element that are configured to enable the signal of the predetermined frequency band to pass at a predetermined gain. Here, the predetermined gain may include a common mode driven gain. For example, the common mode driven gain may be predetermined at a ratio of input impedance to a sum of input impedance and shield impedance, for example,

ZA+ZBZA
according to Equation 5.

The common mode interacting unit540may include a frequency band changing unit configured to change a frequency band of the common mode signal for compensating for the biosignal according to a control of a user. Also, the common mode interacting unit540may include an adjusting unit configured to adjust a gain and a phase of the common mode signal to correspond to a predetermined common mode driven gain. For example, when the common mode interacting unit540is configured as a resistor-capacitor (RC) network, the adjusting unit may include a variable resistance and a variable capacitor configured to adjust a pass band frequency and a pass band gain.

The shield may be made using a conductive material and may block other noise occurring outside the CCE510. The shield may feed back the shield voltage interacting with the common mode signal as a biosignal sensed on the electrode face.

The pre-amplifier may amplify the biosignal interacting with the common mode signal. For example, the pre-amplifier may be configured as a buffer to transfer two biosignals to the differential amplifier520. The transferred biosignals may be used to output the common mode signal and a differential signal.

An IDC biosignal measurement device, for example, a device to measure a biosignal using a common mode driven shield according to an example may include the common mode interacting unit540, the CCE510, and the differential amplifier520. An operation of the common mode interacting unit540and the CCE510is described above and thus, a further description related thereto will be omitted.

The differential amplifier520may extract a differential signal by amplifying a differential component between two biosignals transferred from the pre-amplifier. For example, the differential signal may include an ECG signal.

FIG. 6is a diagram illustrating an example of a CCE610. Clothes691, the CCE610, and a pre-amplifier613may be similar to the clothes391, the CCE310, and the pre-amplifier313ofFIG. 3. A shield voltage of the CCE610may interact with a common mode signal through a common mode interacting unit640.

According to an example, a voltage, such as a shield voltage of a shield configured to surround a capacitive electrode, may interact with the common mode signal. Thus, it is possible to decrease common mode noise. The CCE610may be used alone, or may be used simultaneously by applying a right-leg-driven (RLD) ground.

The CCE610may have a small ground size and thus, may be applied to an IDC biosignal measurement device having a poor ground, and may be simultaneously applied together with the RLD ground to thereby further decrease common mode noise of the biosignal measurement device.

The CCE610having a relatively reduced ground size compared to an existing ground may be applied to a device having a limited size on an electrode and a ground, such as a wearable IDC biosignal measurement device. Due to enhanced convenience in measurement, a biosignal may be measured without awareness of a measurement target. Further, the CCE610may be applied to various heartbeat based applications. For example, the variety of heartbeat based applications may include an R-peak based ECG measurement device, a sleep prevention device, a daily sleep and stress monitoring device, and a companion animal monitoring device.

A circuit in which a common mode driven shield is configured using a sum of outputs of a high band pass (HBP) filter and a low band pass (LBP) filter, a circuit in which a common mode driven shield is configured using a HBP filter, and a common mode driven circuit in which a gain is determined to maximize a rate of decrease in a predetermined frequency band will be described with reference toFIG. 7throughFIG. 9.

FIGS. 7A and 7Bare diagrams illustrating an example of a common mode interacting unit including a combination of an LBP filter741and an HBP filter742. It is noted that the common mode interacting unit may be referred to as a common mode interworking unit or a common mode interacting unit which enables the shield voltage to interwork or interact with the common mode signal.

FIG. 7Ais a diagram illustrating an example of a combination of the LBP filter741and the HBP filter742. A cutoff frequency of two filters, for example, the LBP filter741and the HBP filter742may be determined as 2πCBRB, a pass band gain of the LBP filter741may be determined as (RA+RB)/RA, and a pass band gain of the HBP filter742may be determined as (CA+CB)/CB. A common mode driven gain optimized based on the combination of the LBP filter741and the HBP filter742may be expressed as in Equation 6 below. Here, in addition to a first filter, an nthfilter may also be used for each of the LBP filter741and the HBP filter742. For example, n may denote a natural number greater than or equal to “1”.

FIG. 7Bis a diagram illustrating an RC network circuit of the combination of the LBP filter741and the HBP filter742ofFIG. 7A. By configuring resistances (RAhand RBh) and capacitors (CAhand CBh) as illustrated inFIG. 7Band by determining a magnitude of each passive element according to Equation 7 below, the common mode signal to which the predetermined common mode driven gain is applied may interwork with the shield voltage.

According to an example, it is possible to adjust a gain and a phase of the common mode signal to correspond to a predetermined common mode driven gain using an adjusting unit. For example, the adjusting unit may include RBhand CBhto which a variable element is applied, and may change the gain and the phase of the common mode signal by adjusting magnitudes of RBhand CBh.

FIG. 8is a diagram illustrating an example of a common mode interacting unit including the HBP filter742. Referring toFIG. 8, a common mode driven gain may be configured in a simpler form using a single HBP filter742. In this example, a rate of decrease of common mode noise in a relatively high frequency may be relatively small compared to an optimal gain of the common mode interacting unit including a combination of the LBP filter741and the HBP filter742. In the case of using the single HBP filter742, the common mode driven gain may be expressed according to Equation 8 below. In Equation 8, s denotes a frequency component.

FIG. 9is a diagram illustrating an example of a common mode interacting unit tuned for a predetermined frequency. Referring toFIG. 9, the common mode interacting unit may configure a common mode driven gain using a simple amplifier. As described above, in the case of using the simple amplifier, the common mode noise may not be uniformly decreased within the overall frequency range and a decrease rate thereof may increase in a predetermined frequency portion. For example, a gain may be tuned and used to be suitable for a power noise frequency as given by Equation 9 below. In Equation 9, ω0denotes a frequency component and may be tuned for the power noise frequency.

FIGS. 10A through 10Care diagrams illustrating an example of a magnitude of power noise of a common mode driven shield and a ground shield. Here, a power noise reduction effect of a device to measure a biosignal using a common mode driven shield may be known.

FIG. 10Ais a diagram illustrating a result of measuring a biosignal using the ground shield,FIG. 10Bis a diagram illustrating a result of measuring a biosignal using the unit-gain common mode driven shield, andFIG. 10Cis a diagram illustrating a result of measuring a biosignal using the common mode driven shield to which an optimal common mode driven gain is applied. Referring toFIG. 10B, in the case of measuring a biosignal using the common mode driven shield, the power noise may be significantly decreased. Referring toFIG. 10C, in the case of measuring a biosignal using the optimal common mode driven shield, the power noise may be mostly removed. The power noise may include noise of 60 Hz.

FIG. 11is a diagram illustrating an example of a method to measure a biosignal using a common mode driven shield.

Referring toFIG. 11, in1110, a biosignal of a target is sensed. For example, the biosignal may include an ECG, an electrooculogram (EOG), an electromyogram (EMG), and an electroencephalogram (EEG).

In1120, a common mode signal interacts with a shield voltage in order to compensate for a predetermined frequency band using a common mode interacting unit. The common mode interacting unit may include a filter configured to enable a signal of the predetermined frequency band in the common mode signal to pass, a frequency band changing unit configured to change a frequency band of the common mode signal for compensating for the biosignal according to a control of a user, a driven gain applying unit configured to enable the common mode signal to interwork with the shield voltage by applying a common mode driven gain to the common mode signal at a ratio of input impedance to a sum of input impedance and shield impedance, and an adjusting unit configured to adjust a gain and a phase of the common mode signal to correspond to a predetermined common mode driven gain.

The filter may include at least one of a LBP filter and a HBP filter through which the common mode signal passes. For example, each of the LBP filter and the HBP filter may include a capacitor, a resistance, and a passive element that are configured to enable a frequency band signal to pass at a predetermined gain.

In1130, a shield voltage is fed back to the sensed biosignal. For example, the common mode interacting unit may receive the common mode signal and may output the shield voltage to the same node as an electrode face on which the biosignal is sensed.

In1140, a differential component of the biosignal to which the shield voltage is fed back is amplified. For example, as described above with reference toFIG. 5, the differential component may be amplified using the differential amplifier. Also, the differential component may be extracted using the differential amplifier and the extracted differential component may be amplified using a separate amplifier.

The various units, modules, elements, and methods described above may be implemented using one or more hardware components, one or more software components, or a combination of one or more hardware components and one or more software components.

A hardware component may be, for example, a physical device that physically performs one or more operations, but is not limited thereto. Examples of hardware components include microphones, amplifiers, low-pass filters, high-pass filters, band-pass filters, analog-to-digital converters, digital-to-analog converters, and processing devices.

A software component may be implemented, for example, by a processing device controlled by software or instructions to perform one or more operations, but is not limited to thereto. A computer, controller, or other control device may cause the processing device to run the software or execute the instructions. One software component may be implemented by one processing device, or two or more software components may be implemented by one processing device, or one software component may be implemented by two or more processing devices, or two or more software components may be implemented by two or more processing devices.

A processing device may be implemented using one or more general-purpose or special-purpose computers, such as, for example, a processor, a controller and an arithmetic logic unit, a digital signal processor, a microcomputer, a field-programmable array, a programmable logic unit, a microprocessor, or any other device capable of running software or executing instructions. The processing device may run an operating system (OS), and may run one or more software applications that operate under the OS. The processing device may access, store, manipulate, process, and create data when running the software or executing the instructions. For simplicity, the singular term “processing device” may be used in the description, but one of ordinary skill in the art will appreciate that a processing device may include multiple processing elements and multiple types of processing elements. For example, a processing device may include one or more processors, or one or more processors and one or more controllers. In addition, different processing configurations are possible, such as parallel processors or multi-core processors.

A processing device configured to implement a software component to perform an operation A may include a processor programmed to run software or execute instructions to control the processor to perform operation A. In addition, a processing device configured to implement a software component to perform an operation A, an operation B, and an operation C may have various configurations, such as, for example, a processor configured to implement a software component to perform operations A, B, and C; a first processor configured to implement a software component to perform operation A, and a second processor configured to implement a software component to perform operations B and C; a first processor configured to implement a software component to perform operations A and B, and a second processor configured to implement a software component to perform operation C; a first processor configured to implement a software component to perform operation A, a second processor configured to implement a software component to perform operation B, and a third processor configured to implement a software component to perform operation C; a first processor configured to implement a software component to perform operations A, B, and C, and a second processor configured to implement a software component to perform operations A, B, and C, or any other configuration of one or more processors each implementing one or more of operations A, B, and C. Although these examples refer to three operations A, B, C, the number of operations that may implemented is not limited to three, but may be any number of operations required to achieve a desired result or perform a desired task.

Software or instructions for controlling a processing device to implement a software component may include a computer program, a piece of code, an instruction, or some combination thereof, for independently or collectively instructing or configuring the processing device to perform one or more desired operations. The software or instructions may include machine code that may be directly executed by the processing device, such as machine code produced by a compiler, and/or higher-level code that may be executed by the processing device using an interpreter. The software or instructions and any associated data, data files, and data structures may be embodied permanently or temporarily in any type of machine, component, physical or virtual equipment, computer storage medium or device, or a propagated signal wave capable of providing instructions or data to or being interpreted by the processing device. The software or instructions and any associated data, data files, and data structures also may be distributed over network-coupled computer systems so that the software or instructions and any associated data, data files, and data structures are stored and executed in a distributed fashion.

For example, the software or instructions and any associated data, data files, and data structures may be recorded, stored, or fixed in one or more non-transitory computer-readable storage media. A non-transitory computer-readable storage medium may be any data storage device that is capable of storing the software or instructions and any associated data, data files, and data structures so that they can be read by a computer system or processing device. Examples of a non-transitory computer-readable storage medium include read-only memory (ROM), random-access memory (RAM), flash memory, CD-ROMs, CD-Rs, CD+Rs, CD-RWs, CD+RWs, DVD-ROMs, DVD-Rs, DVD+Rs, DVD-RWs, DVD+RWs, DVD-RAMs, BD-ROMs, BD-Rs, BD-R LTHs, BD-REs, magnetic tapes, floppy disks, magneto-optical data storage devices, optical data storage devices, hard disks, solid-state disks, or any other non-transitory computer-readable storage medium known to one of ordinary skill in the art.

Functional programs, codes, and code segments for implementing the examples disclosed herein can be easily constructed by a programmer skilled in the art to which the examples pertain based on the drawings and their corresponding descriptions as provided herein.