Patent Description:
Understanding that the drawings depict only certain embodiments and are not, therefore, to be considered limiting in nature, these embodiments will be described and explained with additional specificity and detail with reference to the drawings.

With reference to the drawings, this section describes particular embodiments and their detailed construction and operation. The embodiments described herein are set forth by way of illustration only and not limitation. The described features, structures, characteristics, and methods of operation may be combined in any suitable manner in one or more embodiments. In view of the disclosure herein, those skilled in the art will recognize that the various embodiments can be practiced without one or more of the specific details or with other methods, components, materials, or the like. In other instances, well-known structures, materials, or methods of operation are not shown or not described in detail to avoid obscuring more pertinent aspects of the embodiments.

In the following description of the figures and any example embodiments, certain embodiments may describe use of a charging base unit for charging portable handheld data readers such as scanners, optical code reading devices, electronic tag readers, and other mobile electronic devices. It should be understood these examples are merely example uses for the described system and should not be considered as limiting.

Electric arc is a phenomenon that occurs during the opening and closing of a switch in an electric circuit. Electric arc consists of an electrical discharge with a light emission that occurs between two electrodes immersed in a gas between which an electrical voltage is maintained. If the dielectric medium is air, it is referred to as an air arc.

The described phenomenon of electric air arc may also occur between power supply contacts between a portable handheld data reader and a charging base unit. The occurrence of the electric arc generates potentially overheating/overstressing of the power supply contact and consequent deterioration of the contact's efficiency. This may affect the electrical contact between the portable handheld reader and its corresponding charging base unit. This phenomenon may be influenced by the amount of current flowing between the contacts, the dielectric material between the contacts, and the separation speed between the corresponding contacts of the portable handheld data reader and the charging base unit. Environmental conditions (humidity, periodical cleaning of contacts, environment dirt/dust) can also worsen the effects of electric arc.

In the situation where a portable handheld data reader is removed from a corresponding base unit, it is difficult to change the electric arc by changing the dielectric material from air to another material. It is also difficult to change the contact separation speed because the separation speed of the electric contacts is related to user behavior. Accordingly, one may reduce the arc phenomenon by lowering the charging current in advance of the portable handheld data reader being removed from the charging base unit.

Accordingly, the present disclosure contemplates and describes various apparatuses and methods for predicting (e.g., anticipating, foreseeing, etc.) the removal of the data reader from a charging base station and taking specific actions in response. For example, the base station may lower or eliminate the current used to charge the data reader when the data reader is placed in the charging base station before the data reader is removed to avoid/mitigate electric arc. Additional actions are described later in the specification. A data reading system may anticipate the removal of the data reader from the charging base station by detecting the proximity of a user's hand to the data reader with enough time to reduce or eliminate the charging current. The present disclosure also contemplates and describes apparatuses and methods in which the charging base station charges the data reader via wireless charging (i.e. inductive coupling). Predicting removal of the data reader from the charging base station and reducing the charging current by the charging base station may reduce or eliminate overvoltage/overcurrent situations or other related issues.

Various benefits may be realized by reducing or eliminating the charging current before the data reader is removed from the charging base unit. For example, if the charging current is reduced or eliminated before the removal of the data reader from the base unit, a higher charging current may be used to charge the data reader. Higher charging current helps charge a power supply of the portable handheld data reader faster and reduce charging times. As a result, the data reader may be improved with increased operative time, increased battery capacity, and/or reduced charging time. Further, when the charging current is reduced or eliminated before the data reader is removed from the base unit, the electric arc is reduced and damage to the electric contacts between the data reader and the base unit is reduced.

<FIG> illustrate a data reading system <NUM>. In particular, <FIG> illustrates the data reading system <NUM> in a perspective view and <FIG> illustrates the data reading system <NUM> in a top view. The data reading system <NUM> includes a data reader <NUM> and a base unit <NUM> (e.g., cradle). The base unit <NUM> is configured to receive the data reader <NUM> in a longitudinal direction with respect to the base unit <NUM>. The base unit <NUM> is configured to charge a power supply <NUM> disposed on the data reader <NUM> when the data reader <NUM> is coupled with the base unit <NUM>. The base unit <NUM> recharges the power supply <NUM> of the data reader <NUM> through inductive charging. The data reader <NUM> and the base unit <NUM> may be configured to communicate with each other via radio frequency (RF), WiFi, Near Field Communication (NFC) or other wireless communications methods. In some embodiments, the data reader <NUM> and the base unit <NUM> may be configured to communicate data with each other via modulation of the charging field. In some embodiments, a wired data communication connection may be utilized for communicating information between the data reader <NUM> and the base unit <NUM> regarding the predicted removal of the data reader <NUM>.

The data reader <NUM> may be a handheld portable device for scanning and reading barcodes, such as scanners, optical code reading devices, or electronic tag readers (e.g., "radio-frequency identification" (RFID)). The data readers may read (e.g., scan, image, etc.) barcodes, QR codes, symbols, object identifications, electronic tags, etc..

The data reader <NUM> may include a housing <NUM> with a central hand grip section <NUM>, an upper head section <NUM>, and a lower foot section <NUM>. The data reader <NUM> may further include an imaging system <NUM> (see <FIG>). For example, the imaging system <NUM> may be a spot scanner, a charge coupled device (CCD), a complementary metal oxide semiconductor (CMOS), or other suitable system. The housing <NUM> may include a trigger <NUM> on a front side of the housing <NUM> to activate the imaging system <NUM> responsive to the user engaging the trigger with one of their fingers.

The data reader <NUM> further includes a power supply <NUM>. Examples of the power supply <NUM> may include lithium batteries, supercapacitor, etc. The power supply <NUM> is configured to power the components of the data reader <NUM>, such as the circuitry and imaging system <NUM>. The power supply <NUM> is a rechargeable battery that is recharged via an inductive charging, responsive to the data reader <NUM> being placed on or within the base unit <NUM>.

The data reader <NUM> is shown having a generally gun or pistol-shaped housing <NUM> with the trigger-finger actuated trigger <NUM> positioned at an appropriate forward position. Alternatively, the housing <NUM> may be of other shape configurations such as box-shaped with one or more windows or other configurations such as the data readers described in <CIT>, the disclosure of which is hereby incorporated by reference in its entirety, the housing <NUM> preferably equipped with a suitable actuator button(s).

The base unit <NUM> serves as a platform for supporting the data reader <NUM> on a flat surface such as a countertop (which is typically horizontal) or a wall (which is typically vertical). The base unit <NUM> may include a head receiving portion <NUM> and a foot receiving portion <NUM>. The head receiving portion <NUM> is configured to receive (e.g., cradle) the upper head section <NUM> of the data reader <NUM> and the foot receiving portion <NUM> is configured to receive the lower foot section <NUM> of the data reader <NUM>. In this manner, the central hand grip section <NUM> is open and there is a space for the fingers of the user's hand <NUM> to grip the central hand grip section <NUM> to remove (e.g., extract) the data reader <NUM>.

As discussed previously, the base unit <NUM> is configured to recharge the power supply <NUM> of the data reader <NUM> responsive to the data reader <NUM> being placed on or within the base unit <NUM>. In some embodiments not being part of the present invention, the data reader <NUM> may be recharged via conductive charging. Conductive charging requires a physical connection (metal-to-metal) between the power supply <NUM> of the data reader <NUM> and a power source of the base unit <NUM>. The power source of the base unit <NUM> may be alternating current (AC) from a wall outlet. The base unit <NUM> may comprise a metal contact <NUM> to contact a metal contact <NUM> of the data reader <NUM>. In some embodiments not being part of the present invention, the base unit may be a docking station (e.g., cradle) that receives the data reader <NUM>. The cradle may be configured to align the metal contacts <NUM> with the power supply <NUM> to allow current flow.

According to the present invention, the data reader <NUM> is recharged via wireless power transfer ("wireless charging"), i.e. via inductive charging. Inductive charging uses an inductive coil to generate an electromagnetic field to transfer energy between the data reader <NUM> and the base unit <NUM>. Energy is sent through inductive coupling to the data reader <NUM> to charge the power supply <NUM>. The base unit <NUM> may include an induction coil (not shown) to create an alternating electromagnetic field within the base unit <NUM>, and the data reader <NUM> has a second induction coil (not shown) that transfers power from the electromagnetic field and converts it into electric current to charge the power supply <NUM> of the data reader <NUM>. Example embodiments of base units that provide inductive or wireless charging may be found in <CIT>. In some embodiments, the base unit <NUM> may be a charging pad upon which multiple data readers <NUM> may be placed for charging. Such a charging pad may include one or more transmitting coils. In some embodiments, the base unit <NUM> may be configured to adjust the charging current according to the number of data readers <NUM> placed on the base unit <NUM> for charging.

In some embodiments, the base unit <NUM> may include a plurality of apertures <NUM> for securing or temporarily mounting the base unit <NUM> to the countertop or wall via fasteners. The illustrated embodiment of <FIG> merely illustrates a single aperture <NUM> disposed on a side of the base unit <NUM> because <FIG> is a perspective view of the data reading system <NUM>. A second aperture <NUM> may be disposed in a similar position on an opposite side of the base unit <NUM>. In some embodiments, the base unit <NUM> may not include the apertures <NUM>, such as the embodiment illustrated in <FIG>.

The data reading system <NUM> includes a capacitive sensor (such as a capacitive sensor <NUM> in <FIG>) operable to detect the proximity of a user's hand <NUM> to anticipate the removal of the data reader <NUM> from the base unit <NUM>. The capability to predict (e.g., foresee, anticipate, etc.) the extraction or removal of the data reader <NUM> from the base unit <NUM> may activate appropriate actions depending a specific circumstance based on system logic (discussed in more detail below) found within the data reader <NUM> or the base unit <NUM>. For example, if extraction of the data reader <NUM> is anticipated, the data reading system <NUM> can be furtherly configured to reduce or stop the current flow being used to charge the power supply <NUM> of the data reader <NUM> before the data reader is removed from the base unit <NUM> by the user. This may be beneficial when high charging currents are used to charge the data reader <NUM> because it helps avoid the electric arc phenomenon in conductive charging. Electric arcs can damage the metal contacts <NUM> and <NUM>, thus reducing charging efficiency, as mentioned previously. In wireless charging, a reduced charging current helps protect from an overvoltage due to an increase in distance of the coils during extraction.

Sensors include a capacitive sensor capable of detecting a position of the user's hand relative to the sensor. The proximity sensors are configured to detect a threshold change that indicates the approach of the user's hand <NUM>. Responsive to the threshold change is detected, the data reading system <NUM> may take a number of different actions, such as reducing or stopping the current flow to charge the data reader <NUM>, activating the data reader <NUM> from an idle state, activating a locking mechanism, ending communication (e.g., data transfer, data downloads, software updates, etc.) between the data reader <NUM> and the base unit <NUM>, etc. These actions will be described in more detail below.

In the illustrated embodiment of <FIG>, a capacitive sensor <NUM> is disposed in the central hand grip section <NUM> of the data reader <NUM>. The capacitive sensor <NUM> is configured to detect the proximity of a user's hand <NUM>. The capacitive sensor <NUM> is configured to detect and measure anything that is conductive or has a dielectric property different from air, such as the user's hand <NUM>. For example, the capacitive sensor <NUM> is configured to detect a change in capacitance responsive to the user gripping the central hand grip section <NUM> of the data reader <NUM>. Capacitive sensors are sensitive enough to detect a change in capacitance even when the user's hand <NUM> is wearing a glove or if the hand is wet. The detecting range of the capacitive sensor <NUM> is dependent on the size of the capacitive sensor <NUM>. The larger the capacitive sensor <NUM>, i.e. the larger the armature of the capacitive sensor <NUM>, and thus the greater the detection distance. In some embodiments, the detection distance range of the capacitive sensor <NUM> may be from approximately <NUM> to <NUM>.

The capacitive sensor <NUM> illustrated in <FIG> may be shielded within central hand grip section <NUM> of the data reader <NUM> from any of the other electronic components of the data reader <NUM> to avoid any unintentional inference from other electronic circuits of the data reader <NUM>.

In the illustrated embodiment of <FIG>, the base unit <NUM> may include a plurality of capacitive sensors. <FIG> illustrates a top view of the base unit <NUM> with the data reader <NUM> extracted. <FIG> illustrates a detailed view of the plurality of capacitive sensors <NUM>, <NUM>, and <NUM> (e.g., capacitive touch pads). While <FIG> illustrate three capacitive sensors, the present disclosure is not so limited. The base unit <NUM> may have more or fewer than three capacitive sensors. The capacitive sensors <NUM>, <NUM>, and <NUM> are disposed beneath an upper cover <NUM> of the base unit <NUM> and are configured to detect the proximity of a user's hand <NUM>. The capacitive sensors <NUM>, <NUM>, and <NUM> may be aligned in a transverse direction of the base unit <NUM> and disposed between the head receiving portion <NUM> and the foot receiving portion <NUM>. Since the capacitive sensors <NUM>, <NUM>, and <NUM> are disposed between the head receiving portion <NUM> and the foot receiving portion <NUM>, the capacitive sensors <NUM>, <NUM>, and <NUM> are configured to sense a change in capacitance responsive to the user gripping the central hand grip section <NUM> of the data reader <NUM>. Specifically, the capacitive sensors <NUM>, <NUM>, and <NUM> may be configured to detect the change in capacitance responsive to the fingers of the user's hand <NUM> entering the space between the upper cover <NUM> of the base unit <NUM> and the central hand grip section <NUM> of the data reader <NUM>.

In some embodiments, the capacitive sensors <NUM>, <NUM>, and <NUM> may be aligned in a longitudinal direction of the base unit <NUM> between the head receiving portion <NUM> and the foot receiving portion <NUM>. However, different geographic placements of the capacitive sensors <NUM>, <NUM>, and <NUM> to detect the approach of the user's hand <NUM> and predict removal of the data reader <NUM> from the base unit <NUM> are within the scope of the present disclosure.

In embodiments that include more than one capacitive sensor, e.g., <FIG>, the data reading system <NUM> may be more able to more accurately predict the probability of the data reader <NUM> being removed from the base unit <NUM>. For example, the three capacitive sensors <NUM>, <NUM>, and <NUM> of <FIG> are aligned in a transverse direction of the base unit <NUM>. Each capacitive sensor <NUM>, <NUM>, <NUM> may be configured to detect a threshold change in capacitance at different times. For example, if a right-handed person removed the data reader <NUM> from the base unit <NUM> with his right hand, the capacitive sensor <NUM>, the one on the right, may detect the threshold change in capacitance before the capacitive sensor <NUM> on the left. This would be the opposite for a left-handed person removed the data reader <NUM> from the base unit <NUM> with his left hand; the capacitive sensor <NUM> on the left would detect the threshold change in capacitance before the capacitive sensor <NUM> on the right. This helps the data reading system <NUM> to accurately predict the removal of the data reader <NUM> form the base unit because not only is the user's hand near the data reader <NUM> but in is also within the gap between the data reader <NUM> and the base unit <NUM>. In some situations, the data reading system <NUM> may be configured to not adjust the charging current until a predetermined number (e.g., a majority) of the capacitive sensors <NUM>, <NUM>, <NUM> have detected the threshold change in capacitance. For example, in the example of three capacitive sensors, the charging current may be adjusted only after a majority, i.e., two of the three, have detected the threshold change in capacitance.

The capacitive sensors <NUM>, <NUM>, and <NUM> illustrated in <FIG> may be shielded with the base unit <NUM> from any of the other electronic components of the base unit <NUM> to avoid any unintentional inference from other electronic circuits of the data reader <NUM>.

In some embodiments, a proximity sensor <NUM> may be disposed on a side of the base unit <NUM>, as illustrated in <FIG>. The proximity sensor <NUM> may be activated by a specific gesture of the user to reduce the light intensity of the base unit <NUM> during the charging process. Exemplary gestures may include swiping with a finger on the side of the base unit <NUM> at the proximity sensor <NUM>.

<FIG> illustrates a flowchart of a method of recharging a data reader <NUM> using proximity detection of a user's hand <NUM> to predict the removal of the data reader <NUM> from the base unit <NUM>. The data reader <NUM> and the base unit <NUM> each have a processor that in configured to execute the method illustrated in <FIG>. In step S500, the data reader <NUM> is on or within the base unit <NUM>. Responsive to the data reader <NUM> being on or within the base unit <NUM>, the base unit <NUM> charges the power supply <NUM> of the data reader <NUM>. Typically, the current and voltage determine how quickly the data reader <NUM> is recharged. A high current enables the data reader <NUM> to charge quicker. In one embodiment, the charging current may be approximately <NUM> amps. While the high charging current enables quicker recharge, it also may create a bigger electric arc if that data reader <NUM> is removed from the base unit <NUM> while the high current is applied.

In step S510, when the data reader <NUM> is coupled with the base unit <NUM>, the data reading system <NUM> initiates approach detection mode. The approach detection may utilize any of the proximity sensors discussed previously, such as the capacitive sensor <NUM> disposed in the handle of the data reader <NUM>, the capacitive sensors <NUM>, <NUM>, and <NUM> disposed in the base unit <NUM>, or the proximity sensor <NUM> disposed in the side of the base unit <NUM>. Various other configurations of sensors are also contemplated and within the scope of the present disclosure.

In step S520, an approach of user's hand <NUM> is detected responsive to the proximity sensor detecting a threshold change for the appropriate sensor that corresponds with the approach of the user's hand <NUM>. For example, the capacitive sensor may detect a threshold change in capacitance that would indicate that the user's hand <NUM> was approaching to remove the data reader <NUM> from the base unit <NUM>. The threshold change is a predetermined change that predicts a removal of the data reader <NUM> from the base unit <NUM>. If a change in the appropriate sensor is detected, but the detected capacitance change does not surpass the predetermined threshold, then the data reading system <NUM> enacts step S530. During step S530, the data reading system <NUM> continues to measure capacitance changes to detect a potential approach.

In step S540, if an approach is detected, e.g., the threshold change is surpassed, the data reading system <NUM> enacts an "appropriate action. " "Appropriate action" may refer any appropriate action based on the application. For example, it may refer to adjusting the charging current used to charge the power supply <NUM> of the data reader <NUM>, or sounding a warning if the scanner cannot be extracted at a particular moment, etc. The data reader <NUM> may communicate with the base reader (e.g., via RF, modulating the charging field, or other communication methods) to inform the base unit <NUM> when approach is detected. In some embodiments, when the "appropriate action" is enacted, the charging current is stopped. In some embodiments, the amount of charging current is reduced to a lower charging current to reduce the electric arc. A reduced charging current may be around <NUM>-<NUM> amps. In other embodiments, the charging current may be reduced to below <NUM> amps, which helps reduce electric arc and preserve the metal contacts <NUM>.

In step S550, the data reading system <NUM> enacts a timeout period. The timeout period is a predetermined amount of time for the data reading system <NUM>. After the predetermined amount of time expires in S560, the data reading system <NUM> determines in step S570 if the data reader <NUM> is still within the base unit <NUM>. If the data reader <NUM> has been removed from the base unit <NUM>, then the data reading system <NUM> stops the detection of a potential approach in S580. If the base unit <NUM> is a conductive charging (embodiment not being part of the present invention), the charging switch opens when the data reader is disconnected from the metal contacts <NUM>. If the base unit <NUM> is an inductive (e.g., wireless charging system), the base unit <NUM> detects the removal of the data reader based on the coupling factor between the coils decreasing below a predetermined threshold.

In some situations, the data reader <NUM> may still be on or within the base unit <NUM> after the threshold change has been detected. In this situation, it is possible that the user went to remove the data reader <NUM> but decided not to. Accordingly, the data reading system <NUM> returns to step S520 to determine if an approach has been detected, and if not, the "appropriate action" is terminated and the high current (e.g., <NUM> amps) may be applied to recharge the power supply <NUM> of the data reader <NUM>.

In similar situations, the proximity sensors are able to determine if the user has removed his hand from the data reader <NUM>. If the user has removed his hand from the data reader <NUM> and the data reader <NUM> is on or within the base unit <NUM>, then the data reading system <NUM> may charge the power supply <NUM> of the data reader <NUM> with a high current.

According to the present invention, the predetermined threshold change is able to adapt over time. As the data reading system <NUM> is used over a period of time the processor of the data reading system <NUM> is able to adapt the threshold based on repeated instances (e.g., repeated removal of the data reader <NUM> from the base unit <NUM>). Removal dynamics data, such as speed, direction, etc., may be captured by the data reading system <NUM> to with adjusting the predetermined threshold. Such instances include when the threshold was surpassed but the data reader <NUM> was not removed from the base unit <NUM> or instances when the threshold was not surpassed but the data reader <NUM> was removed from the base unit <NUM>. Based on gathered data, the threshold is adapted to better predict the probability of the data reader <NUM> being removed from the base unit <NUM>.

In some embodiments, responsive to a threshold change being detected by the proximity sensor, the data reading system <NUM> may enact a different action other than changing the charging current. In another embodiment, the data reading system <NUM> may change the power used to charge the power supply <NUM> of the data reader <NUM>. In some instances, the power may be reduced or stopped entirely.

Usually when the data reader <NUM> is placed on or within the base unit <NUM>, the data reading system <NUM> places the data reader <NUM> into an idle state (i.e., "sleep mode) to conserve power in the power supply <NUM>. In some embodiments, responsive to the threshold change being detected, the data reading system <NUM> may activate the data reader <NUM> from an idle state to an active state. In this manner, the data reader <NUM> will activate sooner than usual, enabling the user to start using the data reader <NUM> faster than usual.

In some embodiments, the proximity sensor may be used to activate a locking mechanism. For example, after the user cradles the data reader <NUM> on the base unit <NUM>, the data reading system <NUM> detects when the user removes their hand <NUM> from the data reader <NUM> and the data reading system <NUM> may activate a locking mechanism to secure the data reader <NUM> to the base unit <NUM>. The locking mechanism may be a plastic or metal stem that extends from the base unit <NUM> into a stem receiving portion of the data reader <NUM>. When the stem extends into the stem receiving portion, the data reader <NUM> is secured (e.g., locked) to the base unit. Other types of locking mechanism are also contemplated and within the scope of this disclosure.

In some embodiments, responsive the threshold change in capacitance being detected and the data reading system <NUM> predicting the user is about to remove the data reader <NUM> from the base unit <NUM>, the data reading system <NUM> may deactivate the locking mechanism and unlock the data reader <NUM> from the base unit <NUM>. For example, the stem may be retracted from the stem receiving portion of the data reader <NUM>, enabling the user to remove the data reader <NUM> from the base unit <NUM>.

<FIG> is a block diagram illustrating internal components of the circuity for the capacitive sensor <NUM>. The capacitive sensor <NUM> (e.g., pad) includes an upper plastic substrate <NUM>, a metal plate <NUM>, and a lower insulator <NUM>. The metal plate <NUM> may be thin copper plate. The data reading system <NUM> further includes detection logic <NUM> for determining if the threshold change has been surpassed. As discussed previously, the threshold is adaptable over time depending on whether the data reader <NUM> is removed from the base unit <NUM>. The data reading system <NUM> further includes system control logic <NUM>. The system control logic <NUM> is similar to the logic described in <FIG>, and also the control logic has the ability to adapt the threshold change in capacitance to adapt the threshold over repeated removals of the data reader <NUM> from the base unit <NUM>. The data reading system <NUM> may further include a power manager <NUM> that manages the charging current and voltage when the threshold change is surpassed. A battery charger <NUM> is configured to charge the power supply <NUM> of the data reader <NUM> when the data reader <NUM> is on or within the base unit <NUM>.

<FIG> illustrates an exemplary embodiment of the detection logic circuit. The integrated circuit U1 shown in <FIG> may be the AT42QT1011 integrated circuit manufactured by Microchip Technology. This detection logic circuit illustrated in <FIG> enables the data reading system <NUM> to predict removal of the data reader <NUM> from the base unit <NUM> with an advance of <NUM>.

The invention is defined by the set of appended claims. Many variations, enhancements, and modifications of the imager-based optical code reader concepts described herein are possible.

Claim 1:
A data reading system (<NUM>) for reading encoded data on an item, the data reading system comprising:
a handheld portable data reader (<NUM>) for scanning and reading said encoded data, the data reader (<NUM>) comprising a handle for gripping the data reader (<NUM>) and including a power supply (<NUM>), the power supply (<NUM>) being a rechargeable battery configured to power the data reader (<NUM>);
a base unit (<NUM>) configured to receive the data reader (<NUM>) and to charge the power supply (<NUM>) of the data reader (<NUM>) through inductive charging when the data reader (<NUM>) is coupled with the base unit (<NUM>), the base unit (<NUM>) providing a platform for supporting the data reader (<NUM>);
a capacitive sensor (<NUM>) disposed within the handle of the data reader (<NUM>) or within the base unit (<NUM>) and configured to detect an approach of a user's hand based on a threshold change in capacitance; and
a processor in operable communication with the sensor (<NUM>) and the base unit (<NUM>), the processor configured to adjust an amount of current used to charge the power supply (<NUM>) of the data reader (<NUM>) when coupled with the base unit (<NUM>) through inductive charging responsive to the sensor (<NUM>) detecting the approach of the user's hand,
characterized in that the processor is configured to adapt the threshold change in capacitance over time based on repeated instances to better predict the removal of the data reader (<NUM>) from the base unit (<NUM>), the repeated instances including instances when the threshold change in capacitance was surpassed but the data reader (<NUM>) was not removed from the base unit (<NUM>) or instances when the threshold change in capacitance was not surpassed but the data reader (<NUM>) was removed from the base unit (<NUM>).