CN114556123A

CN114556123A - Portable test instrument with backlight battery power exhaustion monitoring function

Info

Publication number: CN114556123A
Application number: CN201980100725.9A
Authority: CN
Inventors: D·埃尔德; B·古思里; M·哈默
Original assignee: Life Scan Intellectual Property Holding Co ltd
Current assignee: Life Scan Intellectual Property Holding Co ltd
Priority date: 2019-07-24
Filing date: 2019-07-24
Publication date: 2022-05-27
Also published as: JP2024001216A; JP2022542085A; CA3148390A1; EP4004571A1; WO2021015756A1

Abstract

A test meter and associated method for monitoring the condition of a backlit battery of a meter, wherein the meter includes a housing, a controller, a display having a backlight, and a battery monitoring circuit. The off time of the meter is measured and compared to a predetermined recovery time of the backlight battery. If the off time of the meter is greater than the predetermined recovery time of the backlight battery, the voltage of the backlight battery is measured at a predetermined time after the backlight is activated and compared to a first predetermined voltage that exceeds the threshold voltage of the backlight battery. If the measured voltage is less than the first predetermined voltage, the measured voltage is compared to a second predetermined voltage between the first predetermined voltage and the threshold voltage. If the measured voltage is less than the second predetermined voltage, a battery depletion warning is displayed.

Description

Portable test instrument with backlight battery power exhaustion monitoring function

Technical Field

The present application relates generally to the field of test meters, and more particularly, to a portable test meter for periodically monitoring a subject and related methods for monitoring battery depletion used in a portable test meter.

Background

Handheld devices, such as portable test meters, typically require a display to convey the results of the test measurements to the user of the meter. For readability in low light conditions, such a display may comprise a backlight. A portable test meter that is compact, lightweight, and long-lived without requiring frequent battery replacement is desirable.

Some technologies, such as Thin Film Transistor (TFT) display technologies, provide enhanced color graphics desired by users. However, without backlight, these displays may be completely unreadable and therefore unsuitable for use in portable test meters that operate for weeks or months without battery replacement, as the backlight cannot be disabled for power saving. Thus, such displays that require constant backlighting are not typically used or considered for such portable test meters.

In addition, the display commonly used in test meters is a passive Liquid Crystal Display (LCD), which is still clearly visible even without an active backlight. Thus, existing architectures for portable test meters do not address the real problems encountered with portable test meters having TFT display screens, which require enhanced monitoring and management of the backlight subsystem to prevent unpredictable power losses to the test meter.

In addition, commonly used battery depletion detection algorithms may only look at the battery voltage before start-up. In this case, the internal resistance, ion mobility, and temperature influence of the battery are not considered. However, such a simple test is only applicable to batteries that experience relatively small and stable current losses.

Drawings

So that the manner in which the features of the invention are understood, a detailed description may be had by reference to certain embodiments, some of which are illustrated in the accompanying drawings. It is to be noted, however, that the appended drawings illustrate only certain embodiments and are therefore not to be considered limiting of its scope, for the scope of the disclosed subject matter encompasses other embodiments as well. The drawings are not necessarily to scale, emphasis generally being placed upon illustrating the features of certain embodiments. In the drawings, like numerals are used to indicate like parts throughout the various views.

FIG. 1A depicts a rear-facing view of a portable test meter, partially cut away, in accordance with aspects set forth herein;

FIG. 1B depicts a front-facing view of a portable test meter, in accordance with aspects set forth herein;

FIG. 2A is a block diagram of a controller used and powered in the portable test meter of FIG. 1A;

FIG. 2B is a plan view of a circuit board including electrical components of the portable test meter of FIGS. 1A and 2A;

FIG. 3 depicts a schematic of a backlight battery and a main battery connected within the portable test meter of FIG. 1A;

FIG. 4 depicts a backlight driver circuit having battery monitoring circuitry for use in a test meter, in accordance with aspects set forth herein;

5A-5B depict voltage recovery characteristics of a battery intended for use as a backlight battery for a test meter, in accordance with aspects set forth herein; and

FIG. 6 depicts a method for monitoring a condition of a backlit battery, such as those having characteristics depicted in FIGS. 5A-5B for a portable test meter, in accordance with aspects set forth herein.

Detailed Description

The following detailed description should be read with reference to the drawings, in which like elements in different drawings are numbered identically. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. The detailed description illustrates by way of example, not by way of limitation, the principles of the invention. The description will clearly enable one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what is presently believed to be the best mode of carrying out the invention.

As used herein, the term "about" or "approximately" for any numerical value or range indicates a suitable dimensional tolerance that allows the portion or collection of components to be used for its intended purpose as described herein. Furthermore, as used herein, the terms "patient," "host," "user," and "subject" refer to any human or animal subject, and are not intended to limit the system or method to human use, although the use of subject technology in human patients represents a preferred embodiment.

The present disclosure relates in part to portable test meters, such as those used to periodically measure a subject's blood glucose level. Some of these test meters are equipped with a primary battery or battery that powers the test meter's built-in controller and display, as well as any measurement subsystems, such as the electrochemical test circuitry for blood glucose monitoring. For those portable test meters equipped with a TFT or similar type of display, there is a further need to power the backlight of the display. Thus, the test meter may further include a dedicated backlight battery and allow for enhanced battery monitoring to facilitate replacement of the backlight battery before it is depleted. More specifically, the main battery may be used to power the controller, display logic, and any measurement subsystems of the test meter, while the dedicated backlight battery may be used only to power the backlight. This configuration allows the use of TFT displays in portable test instruments despite the problem that TFT displays require backlighting to be visible. In one embodiment, the footprint of the portable test meter is reduced due to the use of conventional coin cells as dedicated backlight cells, since coin cells that are not normally available for backlighting are typically operated in the unconventional manner described herein.

Additionally, coin cells (such as CR2032 lithium cells) have been commonly used for portable test meters, but are not suitable for use with high power extraction components such as backlights. The techniques described herein enable the use of these common batteries because they take advantage of a particular usage pattern of the portable test meter, such as those used periodically to measure blood glucose in diabetic patients.

In general, and in accordance with an embodiment, a portable test meter is provided. The portable test meter includes a means for monitoring the backlight battery, such as a battery monitoring circuit. The test meter includes a housing holding a controller for measuring, e.g., periodically, the subject's blood glucose level. The test meter also includes a display, such as a TFT display with a backlight and circuitry for monitoring the dedicated backlight battery. Using a monitoring circuit, the off time of the meter is measured and compared to a predetermined recovery time of the backlight battery. If the off time of the meter is greater than the predetermined recovery time of the backlight battery, the voltage of the backlight battery is measured at a predetermined time after the backlight is activated and compared to a first predetermined voltage that exceeds the threshold voltage of the backlight battery. If the measured voltage is less than the first predetermined voltage, the measured voltage is compared to a second predetermined voltage between the first predetermined voltage and the threshold voltage. If the measured voltage is less than the second predetermined voltage, a battery depletion warning is displayed.

In another embodiment, a method for monitoring the condition of a backlight battery for a portable test meter is disclosed herein. The test meter includes a meter housing that holds a number of components, including a controller, and a display is provided on the meter housing. The display includes a TFT screen and a backlight. The backlight is powered by a backlight battery. According to the method, the off-time of the meter is measured and compared to a predetermined recovery time of the backlight battery. If the off time of the meter is greater than the predetermined recovery time of the backlight battery, the voltage of the backlight battery is measured at a predetermined time after the backlight is activated and compared to a first predetermined voltage that exceeds the threshold voltage of the backlight battery. If the measured voltage is less than the first predetermined voltage, the measured voltage is compared to a second predetermined voltage between the first predetermined voltage and the threshold voltage. If the measured voltage is less than the second predetermined voltage, a battery depletion warning is displayed.

The above-described embodiments are intended to be examples only. Other suitable embodiments are also within the intended scope of the disclosed subject matter, as will be readily apparent from the following discussion.

A specific working example will now be described. First, referring to fig. 1-6, portable test instruments and battery monitoring techniques will be discussed.

Fig. 1A depicts a rear facing view of a portable test meter 10, defined by a meter housing 11, the meter housing 11 having an interior configured and dimensioned to hold a plurality of components. These components include the controller 38 (see FIG. 2A), the main battery 50 and the backlight battery 52. As shown in fig. 1B, the display 14 according to this embodiment includes a Thin Film Transistor (TFT) screen and a backlight disposed on a front facing side of a similar portable test meter 10'. In one example of operation, the main battery 50 powers the controller 38 as well as the TFT display logic. Meanwhile, the backlight battery 52 only powers the display backlight.

Depending on the configuration, the backlight may be a Light Emitting Diode (LED) or an array of LEDs, wherein the array may comprise 1 to 50 LEDs. In other embodiments, the backlight may be a fluorescent device, an electroluminescent device, an Organic Light Emitting Diode (OLED), or any other light source that may be disposed within the housing 11 of the test meter 10, 10' of fig. 1A and 1B.

FIG. 1B illustrates a diabetes management system that includes a portable test meter 10' and a biosensor in the form of a glucose test strip 62. Although the portable test meters 10, 10' have different physical appearances, they operate in substantially the same manner. Note that the meter (meter unit) may be referred to as an analyte measurement and management unit, a glucose meter, a meter, and an analyte measurement device (not shown). In an embodiment, the meter unit may be integrated with an insulin delivery device, an additional analyte testing device and a drug delivery device. The meter unit may be connected to a remote computer or remote server via a cable or suitable wireless technology such as, for example, GSM, CDMA, bluetooth, wireless network, etc. Such a management system is described in more detail in U.S. patent No. 8,709,232B2 entitled "analyte measurement techniques and systems" entitled 4/29 2014, which is hereby incorporated by reference in its entirety.

Referring back to FIG. 1B, a blood glucose meter or meter unit 10' is defined by a housing 11, the housing 11 having a plurality of user interface buttons (16, 18, and 20) disposed on facing surfaces of the housing 11. The display 14 is provided in addition to a test strip port opening 22 configured to receive a biosensor (test strip 62). The user interface buttons (16, 18, and 20) may be configured to allow data entry, menu navigation, and command execution. The user interface button 18 may be in the form of a two-way toggle switch. The number and orientation of the user interface buttons may assume a variety of configurations, with the three (3) interface buttons shown being examples. The data may include values representative of analyte concentrations and/or information related to an individual's daily lifestyle. Information related to a daily lifestyle can include food intake, drug use, the occurrence of health checks, and the general health and exercise level of an individual. The electronic components of the portable test meter 10, 10 'may be disposed on a circuit board 34, as shown in FIG. 2B, with the circuit board 34 disposed within the interior of the meter housing 11, 11'.

FIG. 2A depicts a partial block diagram of a portable test meter showing controller 38 connected to power supply 220. The controller 38 includes a Central Processing Unit (CPU) 212, a Random Access Memory (RAM) 214, an analog-to-digital converter (ADC) 216, and a general purpose input/output (GPIO) 218. The ADC 216 is connected to the backlight battery monitoring circuit and may be used to measure its voltage. The GPIO 218 may communicate with a display to turn on the backlight 60 (see fig. 3), or may communicate with a battery monitoring circuit (see fig. 4).

FIG. 2B (in a simplified schematic) illustrates electronic components disposed on a top surface of a circuit board 34, the circuit board 34 being disposed within the interior of the test meter 10 of FIG. 1A. These electronic components include test strip port connector 22, operational amplifier circuit 35, controller 38, display connector 14a, non-volatile memory 40, clock 42, and first wireless module 46. On the bottom surface of the circuit board 34, the electronic components may include a battery connector (not shown) and a data port 13. Controller 38 may be electrically connected to test strip port connector 22, operational amplifier circuit 35, first wireless module 46, display 14, non-volatile memory 40, clock 42, at least one battery, data port 13, and

user interface buttons

16, 18, 20.

The operational amplifier circuit 35 may include two or more operational amplifiers configured to provide a portion of the potentiostat function and the current measurement function. Potentiostat function may refer to the application of a test voltage between at least two electrodes of a test strip used in conjunction with a test meter. The current function may refer to a measurement of a test current resulting from an applied test voltage. The current measurement may be performed with a current-to-voltage converter. Controller 38 may be in the form of a mixed signal Microprocessor (MSP) such as, for example, texas instruments MSP 430. The TI-MSP 430 can be configured to also perform a potentiostat function and a portion of a current measurement function. In addition, the controller 38 may also include volatile and non-volatile memory. In another embodiment, many of the electronic components may be integrated with the controller in the form of an Application Specific Integrated Circuit (ASIC).

Test strip port connector 22 may be configured to form an electrical connection to a test strip, such as test strip 62. Display connector 14a may be configured to attach to display 14. The display 14 may be in the form of a liquid crystal display for reporting measured glucose levels and facilitating entry of lifestyle related information using

interface buttons

16, 18, 20. More specifically, and in accordance with this embodiment, the display 14 includes a backlight. The data port 13 may accept a suitable connector attached to a connecting lead (not shown) allowing the test meter 10 to be linked to an external device, such as a personal computer. The data port 13 may be any port that allows data transfer, such as, for example, a serial, USB, or parallel port. The clock 42 may be configured to maintain a current time associated with the geographic area in which the user is located, and also to measure time, and as described in more detail later. The test meter may be configured to be electrically connected to a power source, such as, for example, at least one built-in battery, as depicted according to fig. 3.

FIG. 3 schematically depicts further details of a power configuration for the test meter 10 of FIG. 1. In this configuration, the controller 38 is connected to the main battery 50 for supplying power to the controller 38. The backlight battery 52 is used to power a backlight 60 of the display 14 via a backlight driver circuit 54.

Fig. 4 depicts a backlight driver circuit 410 according to an embodiment as used with a battery monitoring circuit 420. The exemplary backlight driver circuit 410 employs a switch-mode boost regulator operating in a constant current configuration. The driving circuit 410 outputs to the LED backlight through the LED _ a and the LED _ K. The LED current is controlled by resistor R32. In this case, a reference voltage (e.g., 500 mV) may be held at pin FB on U10, providing an LED drive current of approximately 10 mA. The battery monitor circuit 420 measures the voltage VBAT2 through an analog-to-digital converter (ADC). For example, to facilitate backlight battery measurements, the controller may pull the signal EN _ VBAT2_ MEAS low, thereby turning on MOSFET Q4. This allows the voltage from BT2 to reach the voltage divider generated by R34/R38. The ratio of these two resistors divides the BT2 voltage by a factor of 1.7 and then feeds the voltage to the ADC. The voltage divider ensures that the BT2 voltage does not saturate the ADC input.

Fig. 5A-5B depict electrochemical voltage recovery characteristics of a lithium coin back-light cell in accordance with aspects set forth herein. For example, if the backlight battery is loaded to 0.8V, when the load is removed, fig. 5A shows that the voltage starts to recover above 2V after approximately 60 seconds. However, a recovery to 99% of the nominal battery voltage of, for example, 3V may take approximately 3 hours, as shown in fig. 5B.

For example, a particular battery model may be selected for use as a back light cell in a portable test meter. Such batteries may be characterized by factory testing to determine the time it will take for the battery to recover to electrochemical equilibrium after being drawn for a period of time (typical usage time of a portable test meter). In the case of a portable glucose meter, which is typically used 3-4 times per day, each for about 2-5 minutes, the battery cycle may be characterized as a full draw of 5 minutes, and the time required for recovery is determined.

Notably, lithium coin cells that exhibit the characteristics of fig. 5A-5B are not ideal for powering the backlight battery of a device that operates continuously and for relatively long periods of time. However, because test meters such as glucose meters are typically only used several times a day for a relatively short period of time during the testing process, lithium coin cells can be used as the backlight cells in such meters by employing monitoring techniques as described herein. These monitoring techniques enable the detection of a depleted battery for timely replacement.

In addition to recovery time characteristics, a battery may exhibit a voltage drop when it is stored at a temperature outside its normal operating range. In such a case, where the battery is well below the nominal operating temperature, the techniques described herein may account for the temperature being outside the operating range by suppressing the battery depletion message during such cycling.

FIG. 6 depicts a method 600 for monitoring the condition of the backlight battery 52 of the portable test meter 10, 10' of FIG. 1A or 1B when using a backlight battery having characteristics similar to those of FIGS. 5A and 5B. As described above, test meters such as blood glucose meters include periodic measurements made over the course of a 24 hour period based on meals and other events (exercise, sleep, etc.). Thus, the test meter will not be powered on all the time for a given 24 hour period, during which time glucose measurements may be taken multiple times, and during a given 24 hour period, measurements may often take less than a minute. For purposes of the present invention and determining that the backlight battery is depleted, it has been determined that the off time of the test meter is an important factor that can be used to determine whether the backlight battery is depleted. In describing the method 600, specific working examples will be given for illustrative purposes only.

In one embodiment, method 600 measures the off time of the meter at block 610 and compares the measured off time of the meter to a predetermined recovery time of the backlight battery. For example, controller 38 may store the backlight usage record to non-volatile memory. In the particular working example for illustrative purposes that will be followed herein with reference to fig. 6, the record may indicate that the last backlight activation was on day X, 1 pm: 08. then, when the meter is next turned on, the meter can obtain the current system time from the on-board clock of the controller. In a specific working example, the current system time may be 5 pm day X: 28. the controller may then subtract the previous activation time from the current system time to determine the off time, which in this particular working example would be 4 hours 20 minutes.

To accurately meter whether the test meter's built-in battery is depleted, the measurement is most accurate when the battery has been allowed to recover from periodic cycling. In this case, the method 600 determines at block 620 whether the off time of the meter is greater than a predetermined recovery time of the backlight battery. In a particular working example, the lithium coin cell may take 4 hours to recover, and thus, in this particular example, the controller may compare the actual off time to the 4 hour recovery time and proceed to the "yes" branch of block 620. Conversely, if the battery has not been allowed to recover sufficiently for a full four hour period, the method 600 proceeds to block 690 at block 620 and no warning message will be displayed. In this case, the meter may perform a main meter routine and allow tests to be performed, such as blood glucose tests.

In other examples, the battery may require anywhere from 10 minutes to 12 hours to recover. The recovery time for a particular battery model used in a particular test meter may be characterized and, therefore, an appropriate value for the recovery time may be predetermined. As described with reference to fig. 5A-5B, characterization of the recovery time of a battery can be performed by controlled testing using N battery replicas and measuring the internal voltage of the battery using a voltmeter.

Continuing, method 600 turns on (energizes) the backlight of the test meter at block 630 and measures the voltage of the backlight battery at a predetermined time after energizing the backlight. The predetermined time may be selected to allow the backlight to be fully activated before the measurement is taken. In a particular working example, the battery monitoring circuit 410 may read the voltage after a predetermined time and the controller may store the voltage in a non-volatile memory. The predetermined time may be selected by a controlled test in which a high speed voltage tester is used in a controlled environment to monitor the backlight cell voltage during the first few seconds of backlight operation to determine how long it must take for the voltage to settle.

Next, the method 600 compares the measured voltage to a first predetermined voltage that exceeds a threshold voltage of the backlight battery at block 640. The first predetermined voltage may be selected to be a sufficiently high voltage such that there is little or no likelihood that the backlight battery is near depletion. Instead, the threshold voltage may be selected to be the minimum possible voltage required to energize the backlight. In one specific example, the threshold voltage may be 0.8V, and the first predetermined voltage may be 2.5V (voltage of a new battery).

The method 600 determines at block 650 whether the measured voltage is less than a first predetermined voltage. In the event that the measured voltage is greater than or equal to the first predetermined voltage, the method 600 proceeds to block 690 and no warning is displayed because the backlight battery is not nearly depleted. In one example, the first predetermined voltage may be set to be equal to a full voltage of a newly installed battery.

If the method 600 determines at block 650 that the measured voltage is less than the first threshold voltage, the method 600 continues to block 660 and compares the measured voltage to a second predetermined voltage, the second predetermined voltage being between the first predetermined voltage and the threshold voltage. The second predetermined voltage may be selected by a test meter and controlled testing of N replicas of the battery (e.g., N = 100). The second predetermined voltage represents a voltage at which the battery is close enough to run out to require user intervention. For example, the second predetermined voltage may be determined by a controlled test until a certain small number of typical meter tests, such as between one and five tests, may be performed before the battery is fully depleted. In one example, the second predetermined voltage may be between 1.0V and 1.2V.

The method 600 determines at block 670 whether the measured voltage is less than a second predetermined voltage. If the measured voltage is not less than the second predetermined voltage, the method proceeds to block 690 and no warning is displayed.

Conversely, if the measured voltage is less than the second predetermined voltage, the method proceeds to block 690 and a battery depletion warning or message is displayed on the meter. In one example, the battery depletion message may be continuously displayed on the meter as a low battery icon. In another example, the meter may need to acknowledge a battery depletion warning before allowing the test to be performed. In another example, a battery depletion alert may indicate the number of remaining test cycles of the meter. In yet another example, the battery-out warning may be escalated or repeated based on the number of times the remaining typical tests may be performed.

In another embodiment, the method may measure a second voltage of the backlight battery at a second predetermined time. For example, the second measurement voltage may be obtained between 1 and 1000 seconds after the first measurement voltage. The second measured voltage may be used to determine a battery voltage drop that occurred during a predetermined time since energizing the backlight. This voltage drop will become larger with each use cycle as the backlight battery is depleted. In examples where a low capacity battery is used to power the backlight, such a battery may only be able to power the backlight for a particular duration before needing to be shut down for a recovery cycle. Thus, if the backlight has been powered for longer than a certain time interval without being allowed to recover, the meter may determine that the battery is only temporarily depleted, rather than permanently depleted. Also, the acceptable on-time of such a battery can be characterized by controlled testing of N replica meters with the battery, and.

Notably, the method 600 described above with respect to blocks 610-680 generally occurs before a meter user tests with a meter. Thus, the user may receive a backlight battery warning and may decide to abandon the test at that time, such as a self-monitoring blood glucose test, and immediately replace the backlight battery. In another example, the user may choose to first perform the test and then subsequently replace the backlight battery. In yet another embodiment, based on the voltage level of the battery after the backlight has been activated, the controller may estimate the number of typical test cycles that may remain before the battery will be completely unable to light the screen, and provide a warning indicating how many tests remaining are possible before the battery is completely depleted.

In another embodiment, in addition to or instead of the battery depletion check described above, a so-called gas metering technique may be employed in which the accumulated energy used by the battery over its lifetime is tracked by measuring the voltage and current over each historical time interval from when a new battery is installed in the system using a meter. Using this technique alone can be error prone because a partially charged battery may be installed in the test meter. However, in conjunction with the other monitoring described above, this technique can eliminate false positives or false negatives. For example, if a known new battery is installed (e.g., a smart battery with a specific identification code to indicate the manufacturer), the meter may override the battery-out warning with accumulated usage data.

While the invention has been described in terms of particular variations and illustrative figures, those of ordinary skill in the art will recognize that the invention is not limited to the variations or figures described. Additionally, where methods and steps described above indicate specific events occurring in a specific order, those of ordinary skill in the art will recognize that the order of the specific steps may be modified and that such modifications are in accordance with the variations of the present invention. Additionally, certain steps may be performed concurrently in a parallel process when possible, or may be performed sequentially as described above. Thus, to the extent that modifications of the invention are included within the spirit of the disclosure or equivalent to the inventions found in the claims, it is the intent of this patent to cover those modifications as well.

To the extent that the claims recite a plurality of elements reciting the phrase "at least one," it is intended to mean at least one or more of the listed elements, and not limited to at least one of each element. For example, "at least one of element a, element B, and element C" is intended to indicate either element a alone, or element B alone, or element C alone, or any combination thereof. "at least one of element a, element B, and element C" is not intended to be limited to at least one of element a, element B, and element C.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" (and any form of comprising, such as "comprises" and "comprising)", "has" (and any form of having, such as "has" and "has)", "contains" (and any form of containing, such as "contains" and "containing)") and "contains" (and any form of containing, such as "contains" and "containing)") are open-ended linking verbs. Thus, a method or apparatus that "comprises," "has," "includes" or "contains" one or more steps or elements possesses those one or more steps or elements, but is not limited to possessing only those one or more steps or elements. Likewise, a step of a method or an element of a device that "comprises," "has," "includes" or "contains" one or more features possesses those one or more features, but is not limited to possessing only those one or more features. Further, a device or structure that is configured in a certain way is configured in at least that way, but may also be configured in ways that are not listed.

The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below, if any, are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description as set forth herein is presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the disclosure. The embodiment was chosen and described in order to best explain the principles of one or more aspects set forth herein and the practical application, and to enable others of ordinary skill in the art to understand one or more aspects described herein for various embodiments with various modifications as are suited to the particular use contemplated.

Claims

1. A portable test meter comprising:

a meter housing;

a controller;

a display on the meter housing, the display including a Thin Film Transistor (TFT) screen and a backlight;

a backlight battery operatively connected to the backlight; and

a battery monitoring circuit operably connected to the controller and the backlight battery, wherein the monitoring circuit:

measuring a turn-off time of the meter and comparing the measured turn-off time of the meter with a predetermined recovery time of the backlight battery;

if the off time of the meter is greater than the predetermined recovery time of the backlight battery, measuring a voltage of the backlight battery at a predetermined time after energizing the backlight and comparing the measured voltage to a first predetermined voltage, the first predetermined voltage exceeding a threshold voltage of the backlight battery;

comparing the measured voltage to a second predetermined voltage if the measured voltage is less than the first predetermined voltage, the second predetermined voltage being between the first predetermined voltage and the threshold voltage; and

displaying a battery-out warning if the measured voltage of the backlight battery is less than the second predetermined voltage.

2. The portable test meter of claim 1, wherein the backlight battery is configured to be periodically loaded for a power-on time followed by a predetermined recovery time, wherein loading of the backlight battery longer than the power-on time reduces the battery internal voltage below the threshold voltage of the backlight battery.

3. The portable test meter of claim 1, wherein the monitoring circuit is further configured to measure a second voltage of the backlight battery at a second predetermined time prior to energizing the backlight, and to display the battery-out warning on a screen of the test meter depending on a comparison of the voltages of the backlight battery at the predetermined time and the second predetermined time.

4. The portable test meter of claim 1, wherein the predetermined time is between 1 and 1000 milliseconds.

5. The portable test meter of claim 1, wherein the monitoring circuit measures a cumulative power draw of the backlight battery during a power-on operation of the backlight and displays the battery-out warning when the measured cumulative power draw is below a predetermined power rating of the backlight battery.

6. The portable test meter of claim 1, wherein the monitoring circuit measures a temperature of the backlight battery and displays a battery-out warning when the temperature is within a predetermined operating temperature range of the backlight battery.

7. The portable test meter of claim 1, wherein the backlight battery is a lithium primary battery.

8. The portable test meter of claim 1, further comprising a main battery operatively connected to the controller and the TFT screen, wherein the main battery and the backlight battery are the same battery type.

9. A method for monitoring backlight battery condition for a portable test meter, the test meter comprising a meter case, a controller, and a display on the meter case, the display comprising a TFT screen and a backlight, the backlight being powered by a backlight battery, wherein the method comprises:

measuring a turn-off time of the test meter and determining whether the turn-off time is greater than a predetermined recovery time of the backlight battery;

energizing the backlight;

measuring a voltage of the backlight battery at a predetermined time after energizing the backlight if an off time of the meter is greater than a predetermined recovery time of the backlight battery;

comparing the measured voltage to a first predetermined voltage, the first predetermined voltage exceeding a threshold voltage of the backlight battery;

displaying a battery-out warning on a TFT screen of the test meter if the measured voltage of the backlight battery is less than the second predetermined voltage.

10. The method of claim 9, further comprising periodically loading the backlight battery for a power-on time followed by a predetermined recovery time, wherein loading the backlight battery longer than the power-on time reduces an internal voltage of the backlight battery below a threshold voltage.

11. The method of claim 9, further comprising measuring a third voltage of a backlight battery before energizing the backlight.

12. The method of claim 1, further comprising displaying a battery depletion warning on a TFT screen of the test meter.

13. The method of claim 9, wherein the predetermined time is between 1 and 1000 milliseconds.

14. The method of claim 9, further comprising measuring an accumulated power consumption of a backlight battery during a power-on operation of the backlight.

15. The method of claim 14, further comprising displaying a battery-out warning when the measured cumulative power draw is below a predetermined rated power of the backlight battery.

16. The method of claim 9, further comprising measuring a temperature of the backlight battery.

17. The method of claim 16, further comprising displaying a battery-out warning when the temperature is within a predetermined operating temperature range of the backlight battery.

18. The method of claim 9, wherein the backlight battery is a lithium primary battery.

19. The method of claim 9, further comprising a main battery operatively connected to the controller and the TFT screen, wherein the main battery and the backlight battery are the same battery type.

20. The blood glucose meter of claim 1, wherein the blood glucose meter is configured to periodically measure a blood glucose level of a subject.