Patent ID: 12191698

DETAILED DESCRIPTION

Overview

The present disclosure is directed to a power delivery system that allows for safe replacement of a battery of an electronic device to be replaced Each battery may simultaneously provide power to the electronic device through the power delivery system. When a battery is depleted or otherwise has a low charge level, the battery may be removed from the electronic device and replaced with a battery having more charge, such as a freshly charged battery. As the power delivery system provides power to the electronic device from multiple batteries connected in parallel when one of the batteries is removed the power delivery system may continue to provide power from the remaining batteries to the electronic device.

The present disclosure avoids the need for equally charged batteries for safe operation of a battery powered device. According to some aspects, this may be accomplished by configuring the device to soft-start a battery upon connection to the device, when the battery being connected has relatively more charge than the one or more other batteries powering the device. The device may also be configured to stop drawing from a battery that has a relatively low charge relative to the one or more other batteries, so as to draw only from the batteries having greater charge until the batteries are at a relatively equal charge. The above described functionality may enable a battery to be replaced while the electronic device remains powered by another battery. In this regard, the power delivery system of the electronic device may include two or more batteries connected in parallel.

A power management subsystem may be configured to balance the current drawn from the batteries when powering an electronic device. The power management subsystem may inhibit the current draw from a battery having a relatively greater charge. The inhibition may be a function of a difference in charge between two batteries. The power management subsystem may be, for example, a programmable integrated circuit (PIC). In one exemplary embodiment, instructions stored on the PCI may, when executed, cause the integrated circuit to restrict current draw from a battery connected to the first electrical connection or second electrical connection if the voltage of the battery exceeds a threshold voltage. This may for example include instructions to monitor gas gauges of the batteries and adjust current drawn therefrom. Alternatively, the power management subsystem may be a hardware circuit at each battery connection that is constructed to open or close a field effect transistor to varying degrees depending on the proportion of the voltage across the battery to the voltage at a power bus for the other systems of the device.

As used herein the term “electronic device” may include any device capable of being at least partially powered by one or more batteries. For example, an electronic device may be a tablet computer, laptop computer, mobile phone, earphones, wearable devices, such as smart watches, fitness trackers, health monitors, smart fashion, etc. As further described herein, the electronic device may be a pair of smart glasses. The smart glasses may include a battery slot at each temple tip. The battery slots may be connected in parallel to the electronics of the device such that the device may continue to operate when one battery is removed. The device may be provided with a battery charging pod and at least one spare battery so that the device may operate indefinitely. The charging pod may be capable of charging the batteries wirelessly, such as by the inclusion of at least one charging coil for inductive charging.

Example Systems

FIG.1illustrates an electronic device20connected to a power delivery system10. The electronic device is connected to a first soft-start circuit100and second soft-start circuit200via a power bus30. As described herein, each soft-start circuit may include a power source, such as one or more batteries that deliver power to the electronic device through the power bus30. Although not shown, electronic device20may include any number of components, circuits, or subsystems, any of which may be independent of one another or grouped within systems or subsystems themselves.

As further shown inFIG.1, the power bus30may receive power through a power management subsystem15of power delivery system10, provided collectively by the first soft-start circuit100and a second soft-start circuit200. AlthoughFIG.1illustrates only two soft-start circuits, any number of soft-start circuits may be included in the power delivery system10. The power management subsystem10is illustrated as including two soft-start circuits100,200by way of example only. In this regard, the power management subsystem may include any number of soft-start circuits. Each soft-start circuit may be similar to first soft-start circuit100, described in detail below, and may each be connected to a common power bus.

FIG.2illustrates first soft-start circuit100. Second soft-start circuit200is generally alike to first soft-start circuit100. That is, the illustration and the following description of the first soft-start circuit100may apply to the second soft-start circuit200. In some instances, power delivery system10may be designed such that second soft-start circuit200differs from first soft-start circuit100in some ways, such as with more or fewer components. Likewise, where a device includes more than two soft-start circuits, each additional soft-start circuit may be compared with first soft-start circuit100, without necessarily being identical to soft-start circuit100.

As shown inFIG.2, first soft-start circuit100includes a battery connection110at which a (first) battery112may be connected. Battery112, though illustrated inFIG.2as being integrated into the soft-start circuit100, may be removable from the first soft-start circuit100. Moreover, although only a single battery112is shown, any number of batteries, such as a battery pack containing multiple batteries, may be connected to the battery connection110.

First soft-start circuit100is configured to compare the voltage of the battery112to the voltage on power bus30. In this regard, the first soft-start circuit100measures the voltage on power bus30to the voltage of the battery112. The first soft-start circuit100may measure the voltage on the bus measuring line150to determine the voltage of the power bus30. The first soft-start circuit may control the power output by the battery112onto power out line151dependent on the outcome of the comparison.

In the example illustrated inFIG.2, first soft-start circuit100will effectively disconnect battery112from power bus30when the voltage on power bus30exceeds the voltage of battery112. By disconnecting batteries holding relatively low charge, soft-start circuits100,200will protect those batteries and the efficiency of the system, as current will be prevented from flowing from power bus30to a battery of lower voltage. In some arrangements, the soft-start circuits100,200may be implemented with a tolerance allowing a battery to remain connected until a difference or ratio between the power bus30voltage and the battery voltage reaches a minimum threshold. Such tolerance may be provided by, for example, modifying comparison lines154,155, described below, or by adding a Schmitt Trigger circuit to the soft-start circuits100,200.

The first soft-start circuit100will restrict power from battery112to power bus30when the voltage of battery112exceeds the voltage on power bus30. When the voltage of battery112exceeds the voltage on power bus30, the degree to which first soft-start circuit100restricts connection between battery112and power bus30will increase as the difference between the voltages increases. That is to say, the amount of power output by the battery112onto the power bus30may be prevented or limited when the voltage of the battery112is larger than the voltage on the power bus30. Soft-start circuits100,200according to the illustrated example will therefore protect depleted batteries and the efficiency of the device by preventing unintended rushes or redirection of current as batteries with a higher charge are connected. By restricting output from batteries carrying a higher voltage than power bus30, soft-start circuits100,200will also protect main system20from inrush current when a freshly charged battery is connected. Since the restriction of the connection has a direct relationship with the amount that the voltage of a battery exceeds the voltage on power bus30, the restriction will decrease over time, as further described herein.

The first soft-start circuit100will provide an unobstructed connection between battery112and power bus30when the voltage of battery112equals the voltage on power bus30. The soft-start circuits100,200may be modified from the numerical ratios stated herein and the arrangement illustrated inFIG.2to allow unobstructed connection between battery112and power bus30when the voltage of battery112differs slightly from voltage on power bus30as well. The amount of difference tolerable for unobstructed connection depends, at least in part, on the chemistry and type of battery112. Any plural number of soft-start circuits according to the following description of first soft-start circuit100may therefore be connected to a common power bus30to enable batteries at various levels of charge to be safely connected or disconnected from respective soft-start circuits without interrupting operation of main system20.

To accomplish the above described comparison between the voltage of battery112and the voltage on the power bus30, positive comparison line154and negative comparison line155are connected to a positive input121and a negative input123, respectively, of an operation amplifier (op-amp)114of the first soft-start circuit100. The positive power supply terminal115of op-amp114is connected to power bus30, while the negative power supply terminal117of op-amp114goes to ground119. As such, op-amp114is powered by power bus30. Although a number of grounds are shown inFIG.2, for clarity only ground119is labeled.

Positive comparison line154is connected to a voltage divider formed between battery out line152and battery ground line153. As shown inFIG.2, battery out line152is connected to battery connection110and battery ground line153is connected to ground. The voltage divider is formed by resistor120and resistor122. The resistors may be sized such that the voltage between resistor120and resistor122is within the operating parameters of the op-amp114. For instance, resistor120may be 10 kiloohm (K) and resistor122may be 1 K. Resistors120and resistor122are arranged in series to act as a voltage divider between battery out line152and battery ground line153.

Positive comparison line154is connected between resistors120,122, and thus carries a fraction of the voltage of battery112. Capacitor124, for which a suitable capacitance may be 1 microfarad (μF), is arranged in parallel with resistor122to act as a filter. Voltage on positive comparison line154and into positive input121will therefore be generally proportional to voltage across battery112.

Similarly, negative comparison line155is connected to bus measuring line150to carry a fraction of the voltage on the bus measuring line150. Resistor126and resistor128, for which suitable resistances are 10.1 K and 1 K, respectively, are arranged in series between bus measuring line150and ground to act as a voltage divider. Negative comparison line155is connected between resistors126,128, and thus carries a fraction of the voltage of power bus30. Capacitor130, for which a suitable value is 1 μF, is arranged in parallel with resistor128to act as a filter. The voltage on negative comparison line155and into negative input123will therefore be generally proportional to the voltage on power bus30.

The positive input121and negative input123to op-amp114are therefore proportional to the voltages of battery112and power bus30, respectively. As such, the output from op-amp114will vary as the relationship between the voltages of battery112and power bus30varies.

Op-amp114outputs on op-amp output line156to a gate of a governance transistor116, which is a normally off transistor that will turn on as voltage at its gate increases beyond voltage at its source. In the illustrated example, governance transistor116is an enhancement type N-channel metal oxide semiconductor field effect transistor (MOSFET). The source of governance transistor116is connected to ground, so the drain-source conductivity of governance transistor116will largely depend on the output of op-amp114.

A governing line157connects the drain of governance transistor116to the gate of an output transistor118, which is a normally off transistor that will turn on as the voltage at its gate falls below the voltage at its source. In the illustrated example, output transistor118is an enhancement type P-channel MOSFET. Battery out line152is connected to the source of output transistor118and, through a resistor132, to governing line157. Voltage on governing line157is thus proportional to the voltage of battery112at a magnitude depending on the degree to which governance transistor is turned on, which in turn depends on the relationship between the voltages of battery112and power bus30. Power out line151connects the drain of output transistor118to power bus30. Thus, the connection between battery112and power bus30is throttled by output transistor118by an amount depending on the relationship between the voltages of battery112and power bus30. Specifically, output transistor118will be completely off when the voltage on power bus30exceeds the voltage of battery112, output transistor118will be completely on when the voltage on power bus30equals the voltage of battery112, and when the voltage of battery112exceeds the voltage on power bus30, output transistor118will be partially on to a degree that is inversely proportional to the difference between voltages.

As shown, first soft-start circuit100includes resistors and capacitors. Numerical values for suitable resistances and capacitances of these elements are set forth herein. Such values are suitable at least for a battery112with capacity for, for example, equal to or about 3.8 volts at maximum charge. Such values are merely examples and may differ in other arrangements according to the present disclosure. For example, the values may be increased or decreased in proportion with one another. For that reason, the disclosed values also indicate suitable ratios between the resistances and capacitances of the elements of first soft-start circuit100. Individual values may also be varied without entirely altering the function of first soft-start circuit100. For each resistance or capacitance described herein, values greater or less than the stated value by 10% of the stated value are also within the scope of the disclosure. All ratios between values resulting from such variation of individual values are also contemplated.

Resistor132and resistor136, for which suitable resistances are 100 K and 10 K, respectively, are arranged in series between battery out line152and governance transistor116to act as a voltage divider. Governing line157is connected between resistors132,136, and thus carries a fraction of the voltage of battery out line. Capacitor134, for which a suitable capacitance is 0.01 μF, is arranged in parallel with resistor132to act as a filter. Capacitor138, for which a suitable capacitance is 0.47 μF, is also connected in parallel with resistor136and across the drain and source of governance transistor116, to act as another filter.

FIG.3illustrates another electronic device320connected to a power delivery system310. As illustrated, the electronic device is connected to the power delivery system via power bus330. Power is supplied to bus330by a power management subsystem315including a programmable integrated circuit (PIC)318, first soft start switch342, and second soft start switch352. The first soft start switch342is controllable by PIC318to throttle power drawn from a removable first battery340, and second soft start switch352is controllable by PIC318to throttle power drawn from a removable second battery350. The power delivery system is illustrated with two soft-start switches342,352and two batteries340,350by way of example only, and alternative arrangements may have any plural number of soft-start switches and batteries generally like those described here.

First battery340includes a first cell344and a first gas gauge346, and second battery350includes a second cell354and a second gas gauge356. Gas gauges346,356measure charge held by their respective cells344,354, such as through temperature measurements. PIC318may monitor gas gauges346,356, and thereby the charge held by cells344,354.

PIC318may include a processor and a non-transitory computer readable memory medium carrying instructions that, when executed, cause PIC318to read gas gauges346,356and control soft-start switches342,352to prevent unintended current rushes or redirections as batteries340,350are connected or disconnected, without interruption to the operation of main system320as long as at least one battery340,350carrying sufficient charge remains connected, in a manner similar to that described above with regard to soft-start circuits100,200.

In one example, PIC318may be programmed to control soft-start switches342,352to disconnect a battery340,350carrying a cell344,354with a lower voltage than a voltage on bus330, as estimated from measurements through gas gauges346,356. PIC318may be programmed to control soft start switches342,352to, upon connection of a battery340,350carrying a cell344,354with a greater voltage than a voltage on bus330as estimated from measurements through gas gauges346,354, initially restrict a connection between the cell carrying the higher voltage and the bus330. PIC318may further be programmed to decrease such restriction over time, thus soft-starting the newly connected battery.

In another example, the memory medium of PIC318may carry instructions that, when executed, cause PIC318to execute a power management logic illustrated by the flowchart ofFIG.4. The logic410may be followed independently with regard to each connection point where a battery, such as batteries340,350, may be attached. PIC318may begin at step414by checking, continuously or at intervals, whether a battery is attached to a given battery connection point. When a battery, such as first battery340, is detected as connected, PIC318will read the gas gauge at step418, such as first gas gauge346.

After acquiring the measurement from the gas gauge, PIC318will determine whether the battery cell, such as first battery cell344, is healthy by comparing the gas gauge measurement to a predetermined threshold at step422. A measurement exceeding the predetermined threshold will indicate that the cell carries a certain minimum amount of charge to be considered “healthy,” while a measurement below the predetermined threshold will reveal the battery cell to be “unhealthy.” In the illustrated example, if the cell is found unhealthy, PIC318may send a warning message at step426to a user through an output system or user interface of the electronic device. However, in other arrangements, no warning message is sent.

If the cell is determined to be healthy, PIC318will prevent an inrush current by activating the respective soft-start switch at step430to restrict connection between the cell and bus330by a gradually decreasing amount.

The cell, whether healthy or unhealthy, may then remain connected to bus330until the battery holding the cell is detached. The PIC318may monitor for detachment of the cell at step434. After the battery is detached, PIC318may return to monitoring the battery connection point at step414for connection of a battery.

FIG.5Aillustrates an example of an electronic device500wherein any of the foregoing power delivery systems may be implemented. In the illustrated example, device500is a pair of smart glasses. In the illustrated example, the device may include any operating hardware typical of smart glasses, such as user interface systems, a projector, a microphone, a speaker, a camera, a radio, wireless communication systems, or any combination of the foregoing.

Smart glasses500include a left temple510and a right temple520, which end, respectively, in a left temple tip515and a right temple tip525. Battery connections or connection points according to the above described power delivery systems10,310and power management subsystems15,315may be located anywhere in the smart glasses510, with, in some examples, each of the temple tips515,525including one connection or connection point. The soft-start circuits100,200or soft-start switches342,352may also each be included in a respective one of the temple tips515,525, or elsewhere within a respective one of the temples510,520, or anywhere else in the smart glasses500.

Batteries may be removably connected to the connections or connection points within temple tips515,525. In addition or in the alternative, temple tips515,525may be removably connected to the respective temples510,520. Thus, in various examples, when a battery needs to be replaced, a user may replace the battery itself, or may remove the temple tip515,525containing the battery and replace it with a charged temple tip.

FIG.5Billustrates a charging pod555that may be used with smart glasses500or any other implementation of the above described power delivery system10,310and power management subsystems15,315. Charging pod550according to the illustrated arrangement includes two charging slots555for receiving and charging a112or a battery340,350(referred to generically as “batteries” below) according to the foregoing arrangements10,310. However, in alternative examples, charging pod550may have only one charging slot555, or any other natural number quantity of charging slots555. Charging pod550may be configured to receive power from any suitable power source, such as a typical plug for a wall outlet, or any variety of USB or similar electronic connection.

Charging slots555may be any type of apparatus used for charging batteries. In some examples, charging slots555are inductive charging coils capable of wirelessly charging the batteries. However, in other examples, charging slots555may include electrical contacts for conductively charging the batteries. According to the above described alternative arrangements of the temple tips515,525, the charging slots555may be configured to receive and charge the batteries alone, or the charging slots555may be configured to receive one of the temple tips515,525, and to charge the battery contained within or connected to a received temple tip.

Charging pod550may be part of a system including electronic device500, or any device including power delivery systems10,310according to the present disclosure, and at least one rechargeable battery. The system may include, for example, two, three, four, or more batteries. Since the above described power delivery systems10,310, enable uninterrupted operation of electronic device500as batteries are individually connected or disconnected, as long as one charged battery, or a sufficient minimum number of charged batteries, remains connected to device500, inclusion of plural batteries in the system enables device500to operate indefinitely. Where multiple batteries are provided, one battery may power device500while another is charged in pod550. A charged battery may be connected to device500before disconnecting a relatively depleted battery from device500and charging the depleted battery with pod550. Thus, shutdown of device500is not necessary.

Although the concept herein has been described with reference to particular examples, it is to be understood that these examples are merely illustrative of the principles and applications of the present concept. It is therefore to be understood that numerous modifications may be made to the illustrative examples and that other arrangements may be devised without departing from the spirit and scope of the present concept as defined by the appended claims.