Wireless headset system for the automobile

A wireless headset system (and method) for connection to a gateway such as a mobile cellular phone that includes a dock assembly and a wireless headset. The dock assembly includes a presence sensor, a first docking connector, and a circuit for sending a connection signal to the first docking connector in response to a triggering of the presence sensor. The headset includes a second docking connector for releasably connecting with the first docking connector, and connection circuitry for initiating a wireless connection with the gateway (e.g. mobile cellular phone) in response to receiving the connection signal via the first and second docking connectors. The dock assembly further includes a power connector for receiving electrical power (e.g. from a car cigarette lighter connector) and for supplying the electrical power through the first and second docking connectors and to a battery in the wireless headset.

FIELD OF THE INVENTION

This invention relates to the field of wireless audio headsets that are used in conjunction with mobile cellular phones, and in particular to hands-free communication systems for automobiles utilizing such headsets.

BACKGROUND OF THE INVENTION

Bluetooth® is a short-range, open wireless communications standard that includes different transmission modes and can simultaneously accommodate different types of devices. Bluetooth is often referred to as a PAN (Personal Area Network) and has the ability to carry real time voice data via a SCO (Synchronous Connection Oriented) link. An SCO link is a digital transmission mode where voice packets transmitted back and forth between an audio gateway (e.g. a mobile cellular phone) and a headset are sent based on a clock common to both devices. Packets that are not received by one of either the headset or audio gateway are not retransmitted. The Bluetooth specification in its entirety is available for download at www.bluetooth.org. Key specification documents include the Bluetooth Core Specification v1.2, Hands-free profile and Headset profile, all of which are incorporated herein by reference. While the present invention is described with respect to headsets and systems utilizing the Bluetooth standard, it is not necessarily limited to this particular communications protocol.

Wireless audio gateways that utilize Bluetooth are known. Such gateways are sources of audio, such as a mobile cellular phone, that route audio transmissions from one communications system (e.g. a cellular network) to another communications system (e.g. a Bluetooth wireless transmission system). A wireless transmission system can include a wireless headset, which is a wearable audio communication device that includes a wireless transceiver, a microphone, a speaker (often called a receiver) and a battery. The headset can both receive an audio transmission and play the transmission for the wearer, as well as send the wearer's voice as an audio transmission. A typical headset includes controls for answering and ending calls, for adjusting the volume of the audio, and for turning the headset on and off. Recently, more models of mobile cellular phones are including the gateway feature.

Wireless headsets using the Bluetooth communications protocol allow users to conveniently communicate via their mobile phone without the constraint of a wire running from the headset to the phone. Use of a wireless headset eliminates the tangling of wires that is so common with wired headsets. Wireless headsets afford new conveniences, such as allowing a user to leave their phone in their pocket, briefcase, or purse. When the phone rings, the user can quickly don the headset and answer the call by activating the answer button on the headset. When used in an office situation, the user of a wireless headset can roam away from their desk wearing the headset, and not have to carry their mobile phone with them. Some users choose to constantly wear the headset, which further reduces the effort required to answer a call. This function is particularly useful in the car while driving. In fact, some jurisdictions have passed laws that prohibit holding a phone while operating a motor vehicle.

Wireless automotive hands-free systems (hereafter hands-free system) are also well known. Such systems are located in automobiles and include a wireless transceiver, a microphone for picking up a user's speech, and a speaker system for playing the caller's audio transmission. Like headsets, the hands-free system includes controls for answering and ending calls, and for adjusting the volume of the audio.

Hands-free systems for use in automobiles have been developed to enable drivers to make and receive calls with minimal physical and cognitive interaction. For example, answering a phone call requires a single button activation. Hands-free systems use speakers to play the caller's voice. The drawback to hands-free systems is that there is no privacy during the call. Everyone in the car listens to the conversation. Additionally, hands-free systems can produce poor quality transmitted audio because the microphone is usually located far away from the user's mouth and the car is a noisy environment. Therefore, hands-free systems, especially aftermarket integrated systems that plug into cigarette lighters, can be particularly unpleasant to listen to at the other end of the conversation.

One problem with headsets and hands-free systems is that when the phone moves out of range of the headset or hands-free system, the connection is lost. One function that is occasionally implemented in headsets and hands-free systems is to automatically and periodically page the mobile phone to which it was last connected in an attempt to reconnect. In theory, the process works like this: a headset and phone are paired and connected. If the phone moves out of range of the headset and the connection is lost, the headset will begin to continually page (attempt to reconnect to) the phone. When the phone again comes into RF range of the headset, they automatically reconnect. Ideally, this would take only a few seconds.

In the case of when a headset is used in a car, the reconnect function in practice is not reliable. Many headsets don't implement the reconnect function because its reconnection duty-cycle requires power to page the phone, thus reducing the talk time and standby time (battery life) of the headset. Some headsets will only attempt to reconnect for a finite length of time and then stop paging the phone to conserve battery power.

Another problem with using headsets in a car is that if the wearer doesn't want to constantly wear the headset, it is easily lost or misplaced of because there is no fixed storage spot for the headset. The motions of the car may cause the headset to move around or fall between the seats. Headsets are small and not easily located, especially in a dark car.

Wireless headsets, although convenient, impose the requirement of having to be charged. A user of a wireless headset already must remember to charge their mobile phone. There are many other popular devices that user's must remember to charge, such as portable MP3 players, Personal Digital Assistants (PDAs), and gaming devices. A wireless headset is just one more item that must be carried to the charging location.

Some manufactures have attempted to make chargers that work with both mobile phones and headsets. For example, the Motorola H500 headset includes a USB-type connector that is used for charging, and thus can be charged using the same car cigarette lighter charging adapter that is used to charge Motorola mobile phones that also include the same USB connector. However, when the headset is being charged, it is inactive (meaning that it is not connectable to the phone). Furthermore, when the headset is unplugged, it doesn't automatically connect to the phone. If a call is received while the headset is charging, the user must unplug the headset and cycle power to the headset, which would take too long and the call would be missed. Since charging the headset requires plugging it into the USB connector at the end of a cable, it is a two-handed operation that requires a substantial amount of the user's attention and manual dexterity, and can be difficult for the driver of a car to accomplish while driving. Lastly, the mobile phone usually cannot be charged while the headset is charging in the car, because most cars have only one cigarette lighter.

FIG. 1shows the Jabra model BT250 headset manufactured by GN Netcom of Denmark, in a charging dock. This dock can be used in the car in conjunction with an automotive DC-to-DC cigarette lighter adapter. However, it also takes two hands to place the Jabra BT250 into the dock, or remove the Jabra from the dock, due to the tight friction fit between the headset and the dock. Furthermore, the headset is not in a functional state while charging. If the user's phone rings, it is unlikely that the headset can be removed from the dock, powered up and connected to the mobile phone in time to answer the call.

What is needed is a wireless headset system for an automobile that provides an effective docking solution for a wireless headset that allows operation during charging and easy removal for answering calls. The system should also incorporate an improved automatic reconnection function such that the headset battery is not needlessly drained, yet is transparent to the user during use. Lastly, the system should allow for simultaneous charging of the phone and headset.

SUMMARY OF THE INVENTION

The present invention solves the aforementioned problems by providing a wireless car headset system that automatically initiates a reconnection between a gateway and the headset when the presence of the user is detected while the headset is docked with a docking assembly.

A wireless headset system for connection to a gateway includes a dock assembly and a headset. The dock assembly includes a presence sensor, a first docking connector, and a circuit for sending a connection signal to the first docking connector in response to a triggering of the presence sensor. The headset includes a second docking connector for releasably connecting with the first docking connector, and connection circuitry for initiating a wireless connection with a gateway in response to receiving the connection signal via the first and second docking connectors.

A method of connecting a wireless headset to a gateway includes removably connecting a wireless headset to a dock assembly via an electrical connection, detecting the presence of a user using a presence sensor, sending a connection signal from the dock assembly to the wireless headset via the electrical connection in response to the detection of the presence of a user, and initiating a wireless connection between the wireless headset and a gateway in response to the receipt of the connection signal by the wireless headset.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is a wireless headset system that incorporates a convenient docking solution and triggers the reconnection function based upon sensing the presence of the user. Referring now toFIG. 2, a wireless headset system202for the automobile is comprised of a car charging dock204and a wireless headset206. The wireless headset206attaches with minimum effort to the car charging dock204via a magnetic coupling. An LED lightpipe ring68on the charging dock204lights in response to detected presence of a user. When docked on car charging dock204, wireless headset206is triggered to reconnect with the user's mobile phone when the presence of the user (e.g. through vibration sensing) is detected. The reconnection function is terminated, and the LEDs76a-76hof lightpipe ring68are switched off after an interval of time without vibration. The reconnection function can be switched off via a switch on car charging dock204. Car charging dock204also includes an auxiliary cigarette lighter 12-volt port so that a mobile phone can be charged while wireless headset206is docked and charging. The components of wireless headset system202for the automobile will be described below in more detail, followed by a description of its operation. It should be noted that while the present invention is described with respect to a particular configuration and Bluetooth wireless protocol, certain other configurations and protocols can be used and still be within the scope of the present invention.

Headset

Wireless headset206, shown inFIGS. 3 and 4, is preferably a Bluetooth v1.2 compliant wireless headset.FIG. 3shows that headset206includes a cover2, an ear hook assembly208for attaching headset206to the wearer's ear, an answer button4for answering calls, a lightpipe6that ports light from a status LED, a volume control button5, and a foam cover8made of open-cell foam that is positioned against the wearer's ear when headset206is donned.FIG. 4shows the angle of the wearing position and how ear hook assembly208secures headset206to the wearer's ear. Headset206also includes an sliding on-off button (not shown).

FIG. 5shows the side of headset206that faces the wearer's ear when in use. A headset charging spring contact (right)11, a re-connect signal spring contact12, and charging spring contact (left)13, are nested inside a charging port10.FIG. 6is an exploded assembly view of headset206with some components removed for the purpose of clarity. Charging port10snaps to an inner cover18. Referring toFIG. 6andFIG. 14, a headset PCB16includes the various electronic components required to implement communications over a known protocol (such as Bluetooth) and includes a Bluetooth single-chip microprocessor100with integral memory, a battery charging integrated circuit98, and charging polarity-swapping circuit96, status LED, an antenna chip, and a plurality of switches. A receiver20is located in a cutout in headset PCB16. Microprocessor100can be (but need not be) a BC358239A single chip Bluetooth v1.2 system, manufactured by Cambridge Silicon Radio of Cambridge, England. Charging spring contact (right)11, re-connect signal spring contact12, and charging spring contact (left13) are soldered to solder pads on headset PCB16. Headset206also includes a rechargeable battery14(e.g. lithium-ion polymer). Cover2, inner cover18, charge port10, and ear hook assembly208are manufactured of injection-molded plastic. Cover2and inner cover18together provide a protective enclosure for wireless headset206.FIG. 7shows that a nickel-plated carbon steel receiver plate22can be attached to the inside surface of inner cover18. A mic-side magnet24made out of neodymium is attached to inner cover18. A receiver-side magnet26made out of neodymium is attached to inner cover18in a circular slot in receiver plate22so that receiver-side magnet26is flush with receiver plate22.

Headset206firmware includes functional implementations of the Bluetooth Headset Profile and Hands-free Profile. Headset206firmware also includes an implementation of the automatic reconnect function, which attempts to page the phone to which headset206was last connected unless headset206is currently connected to a phone. The operation of reconnect function is covered below.

Car Charging Dock

FIG. 8andFIG. 9show that car charging dock204includes a form that allows it to be inserted into and connect electrically to a standard car cigarette lighter receptacle. Car charging dock204includes an external 12-volt contact46and external ground contacts48aand48b, which make contact with corresponding 12-volt and ground contacts inside the cigarette lighter receptacle.FIG. 9shows that dock module210can pivot up approximately 80 degrees to allow access to an auxiliary 12-volt cigarette lighter receptacle (to plug in other devices such as a charger for a cell phone). Right lock bar32and left lock bar34are spring-loaded inside car charging dock204so that they protrude into corresponding right lock bar cavity56and left lock bar cavity58in dock module210, thereby locking dock module210in the closed position, as shown inFIG. 8.

The exploded view of charging dock204inFIG. 10shows a left dock enclosure30and a right dock enclosure28that are fastened together to pivotably constrain dock module210. Right lock bar32, left lock bar34, and lock button36are fit together and slide within car charging dock enclosure such that portions of right lock bar32and left lock bar34protrude from holes in right enclosure28and left enclosure30, respectively. The left lock bar34—right lock bar32—lock button36sub-assembly is forced toward dock module210by a lock spring38. A dock main printed circuit board (PCB)212is also a component in car charging dock204. External 12-volt contact46and internal 12-volt contact42share a common circuit which is connected to a 12-volt input on dock main PCB212. External ground contacts48aand48band internal ground contact44also share a common circuit and are connected to the ground input on dock main PCB212. External 12-volt contact46is constrained by features in dock enclosure (right)28and dock enclosure (left)30. An external 12-volt spring52located inside external 12-volt contact46ensures a compliant contact between external 12-volt contact46and the 12-volt contact inside a conventional car cigarette lighter receptacle.

FIG. 12, an isometric view of the top side of dock main PCB212, shows a flexible circuit connector102, a vibration sensor switch86, and a plurality of components associated with a DC-DC power conversion circuit, all functionally connected by main PCB212. Vibration sensing is used to detect the presence of a user either by detecting movement of the user in the car and/or the operation of the car by the user. An exemplary vibration sensor switch is part number VBS03-02, provided by Oncque Corporation, of Taiwan, which is ideal for sensing vibrations.

FIG. 13, an isometric view of the bottom side of dock main PCB212, shows a microcontroller88, an automatic reconnect on-off switch108, an LED driver integrated circuit (IC)106, and a plurality of components associated with a DC-DC power conversion circuit, all functionally connected by dock main PCB212. An exemplary microcontroller88is an 8-bit microcontroller, part number PIC12F509-I/SN, manufactured by Microchip of Chandler, Ariz. A variety of other support components are required but now shown. The parasitic power usage of dock main PCB212when headset206is not charging or is fully charged, and when microcontroller88is in a low power (sleep) mode and monitoring vibration switch86, is very low (i.e. less than 1 milli-amp).

Dock Module

Now referring toFIG. 11, dock module210comprises a dock module cover60, a lightpipe ring68, neodymium magnets70a70b, a dock charging pads PCB72, a dock module PCB74, LEDs76a-76h, a dock spring-pin connector78, a dock module rear cover62, and a pivot plate64covered by a pivot plate cover66. A flex circuit40electrically connects dock module60to dock main PCB212. Dock module PCB74is electrically connected to dock charging pads PCB72by three wires as schematically shown inFIG. 14. Flex circuit40is also shown with one end located against pivot plate64and retained by pivot plate cover66. Flex circuit40is routed through a hole in pivot plate64and extends inside car charging dock204and is mechanically and electrically connected to dock main PCB212, as shown inFIG. 10. When dock module210is assembled, electrical contact pads on flex circuit40make contact with spring-pins on dock module spring connector78, which are soldered onto dock module PCB74, and which in turn includes an electrical circuit that routes a 7-volt circuit82, a ground circuit84, and a reconnect signal circuit80to dock charging pads PCB72.

Headset Magnetic Attraction and Orientation

Headset206may be connected to car charging dock in one of two orientations where headset is rotated 180 degrees with respect to an axis normal to the cylindrical cross-section of car charging dock204. These two orientations are shown inFIG. 2andFIG. 15respectively. The location of mic side magnet24and receiver side magnet26are shown inFIG. 7. The two orientations are partly controlled by the shape of the cavity in charging port10as it fits onto the corresponding shape of charging pedestal54on dock module210, as well as the polarity of magnets70aand70bin dock module210and magnets24and26in headset206. Mic side magnet24and receiver side magnet26are assembled in inner cover18so the south pole of each magnet faces toward the side of headset206that faces car charging dock204when docked. Magnets70aand70bare installed in dock module cover60so that the north pole of each magnet faces headset206when headset206is docked. Therefore, headset206is always pulled toward car charging dock204in either orientation.

Receiver side magnet26, receiver plate22, and either magnet70aor70b(depending on headset orientation) constitutes one magnetic coupling group when headset206is docked. Mic side magnet24and either magnet70aor70bconstitutes a second magnetic coupling group when headset206is docked. Receiver side magnet26, receiver plate22, and mic side magnet24are sized so that in combination with the receiver metal and magnet, the magnetic force is even between the two magnetic coupling groups when headset206is magnetically docked to dock module210.

Block Diagram of System

FIG. 14is a schematic diagram of wireless headset system202when headset206is attached to car charging dock204. There are two main subsystems in car charging dock204, a DC-DC power conversion subsystem and a vibration sensing and reconnection subsystem. The DC-DC power conversion subsystem includes a plurality of components associated with a DC-DC power conversion function that converts 12-volt DC power to 7-volt DC power for charging headset206and powering LEDs76a-76h. External 12-volt contact46and external ground contacts48aand48bprovide 12-volt power to dock main PCB212when car charging dock204is inserted in a car cigarette lighter. External 12-volt contact46is connected by a wire circuit to internal 12-volt contact42and external ground contacts48aand/or48bare connected by a wire circuit to internal ground contact44.

DC Charging Circuit

Referring toFIG. 14andFIG. 16, DC-DC power conversion sub-assembly includes two circuits: 7-volt charging circuit82and ground circuit84. These circuits run from dock main PCB212, through flexible circuit40, through dock module spring connector78to dock module PCB74, and terminate at the two outer gold plated pads of dock charging pads PCB72. Headset206may be docked in one of two positions which are rotated 180 degrees from each other. Therefore, depending on the orientation of headset206, charging contact spring (right)11makes contact with one of either 7-volt charging circuit82or ground circuit84, via a gold-plated contact on dock charging pads PCB72. Likewise charging contact spring (left)13makes contact with the other of the charging circuit82or ground circuit84. Charging polarity-swapping circuit96is a full bridge rectifier circuit that provides the correct polarity voltage to battery charging circuit98regardless of the orientation of headset206on dock module210. Such a circuit (which provides the desired output polarity to the battery no matter which incoming polarity orientation is provided) can be generically referred to as a polarity insensitive circuit.

Led Power Circuit

DC-DC power conversion sub-assembly also includes an LED power circuit94that is generated by LED driver106and runs from dock main PCB212through flexible circuit40, through dock module spring connector78to dock module PCB74, and then to each of LEDs76a-76h. Microcontroller88includes a control input into LED driver106so firmware programming in microcontroller88controls the power sent to LEDs76a-76h.

Microcontroller88includes an output port that drives a reconnect signal circuit80. This output port runs from microcontroller88, through flexible circuit40, through dock module spring connector78, through dock module PCB74to the center gold-plated contact on dock charging pads PCB72. When headset206is docked on car charging dock204, reconnect signal spring pin contact12on headset206makes electrical contact with the center gold-plated contact on dock charging pads PCB72, so reconnect signal circuit80is connected to a reconnect signal port110on microprocessor100. Firmware resident on microprocessor100monitors the logic level on reconnect signal port110. If the logic level on reconnect signal circuit80and thus at reconnect signal port is low, the reconnect function in firmware is disabled. If the logic level on reconnect signal circuit80and thus at reconnect signal port110is high, the reconnect function in firmware is enabled.

The reconnect function may be turned off by sliding button50of reconnection on-off switch92to the off position. Switch92controls a logic level voltage on a port on microcontroller88. Firmware in microcontroller88controls the logic level on reconnect signal circuit80depending on the state of logic level at a port on microcontroller88.

Vibration Sensing Circuit

Vibration sensor86is functionally connected to a port on microcontroller88so that in the presence of no vibration a logic low level is present at microcontroller88port, and in the presence of vibration a high logic level is present at microcontroller88port.

System Operation

The operation of wireless headset system202will now be described, and in particular with respect to operation in conjunction with a user's mobile phone in a hands-free mode.

Docking

When the user is not actively on a mobile phone call, headset206may be removed from the user's ear and placed on car charging dock204. The act of placing headset206on car charging dock204involves minimal effort by the user because the magnetic attachment means acts to pull headset206into the correct position and orientation when headset206comes in close proximity to dock module210. The protrusion of charging pedestal54into charging port10on headset206stabilizes headset206on dock module210. If headset206is placed in close proximity to dock module210but mic side magnet24and receiver side magnet26are not exactly lined up with magnet70aand70brespectively, the magnetic attraction imparts a rotational force to headset206as well as a linear attractive force, aiding to align headset206as it placed near dock204. The spring forces of charging spring contact (right)11, connect signal spring contact12, and charging spring contact (left)13are such that the magnetic force between the two coupling groups overcomes the combined spring force. Headset206is thus securely attached to car charging dock204and is not jarred loose by vibrations or shocks typically experienced in cars.

Headset Charging

If car charging dock204is powered by cigarette lighter receptacle (where the receptacle is either always powered or only powered when the car's ignition is turned on), and headset206is docked on dock module210, the headset battery charging circuit98will charge rechargeable battery14until rechargeable battery14is fully charged. Rechargeable battery14charges in either of two attached orientations, and battery charging circuit98charges rechargeable battery14regardless of whether headset206is turned on or off.

Headset Connection While Docked

In the description below it is assumed that headset206and a mobile phone have been previously paired and are thus discoverable and connectable with respect to one another using a communications protocol such as Bluetooth. Bluetooth devices that have been paired discover other Bluetooth devices by periodically entering a paging mode (headset), and a page scan mode (phone). The Bluetooth specification describes the process for device discovery, paging and page scan substates, and the establishment of asynchronous connectionless (ACL) links, and synchronous connection-oriented (SCO) links. The process of entering page scan and paging substates, and the subsequent link management and other processes leading up to being connected, is referred to as connecting or reconnecting. When a mobile phone and wireless headset206have established a connection via this process and are ready to initiate an SCO link for audio transmission, and an ACL link for sending AT commands (but no phone call is taking place), they are referred to as being connected. When a call is in progress where audio is being transferred via the SCO connection, the headset206and the mobile phone are said to be in an active state.

Firmware running on microprocessor100in headset206includes a conditional reconnection function, whereby headset206attempts to reconnect with the mobile phone to which it was last connected, if headset206is not already connected to a mobile phone. This reconnection attempt consists of headset206broadcasting page messages. The reconnect function monitors the port on microprocessor100to which reconnect signal circuit80is connected. The reconnect function operates conditionally such that when reconnect signal circuit80is a logic low level, the reconnect function is not executed. When headset206is not docked, or when car charging dock204is not powered, reconnect signal circuit on headset206is pulled to a logic low level. When the dock microcontroller88drives reconnection signal circuit80to a logical high level and then a logical low level, and headset206is docked on dock module210, a logic high level is present at a port on microprocessor100in headset206, and the reconnect function is executed. The falling logic level (i.e. logic level transition) triggers the reconnection function. When triggered, the reconnection attempt lasts approximately 10 seconds. Therefore, ideally, microcontroller80toggles reconnection signal circuit80between a logic low level and a logic high level about once every 30 seconds.

FIG. 17is a flowchart that shows the function of car charging dock204with respect to lighting LEDs76a-76hand for triggering the reconnect function. When headset206is not docked on car charging dock204, reconnect signal circuit80is pulled low at a port on microprocessor100on headset206, so headset206does not initiate a reconnection attempt. When headset206is docked on car charging dock204that is located in a cigarette lighter that is not receiving power (i.e. the key has not activated the ignition switch) the logic level on reconnect signal port110is low so headset206does not attempt to reconnect. If headset206is docked on car charging dock204that is receiving power (i.e. either the key has activated the ignition or the cigarette lighter receptacle always receives power) and the vibration switch86senses vibration, microcontroller88toggles the reconnect signal port110between high and low in a duty cycle causing headset206to attempt a reconnect to the phone to which headset206was last connected (unless it is already connected to an audio gateway such as a mobile phone wherein the headset ignores the toggling signal), during which LEDs76a-76hare turned on, as indicated inFIG. 17. If the reconnection fails, another reconnection attempt will be made upon the next transition of the reconnect signal port110. If the reconnection is successful, the reconnection function ignores subsequent logic level transitions of the reconnect signal port110.

Firmware in microcontroller88includes an elapsed time counter monitoring function. The elapsed time counter starts when power is applied to car charging dock204or restarts the count after every instance that a vibration is sensed by vibration sensor86and by microcontroller88. When the elapsed time monitor function reaches the timeout counter limit without detecting any vibration (e.g. 10 minutes), firmware executing in microcontroller88holds reconnect signal circuit80low which causes the reconnect function in headset206to cease (and LEDs76a-76hare turned off). Referring toFIG. 17, microcontroller88regards its initial power up as a sign of user presence, and starts the reconnection duty cycle and applies power to the LEDs regardless of the state of the vibration sensor.

The result is that as long as a user is present with the key in the ignition, or the vehicle is occasionally moving, or the user makes vibrations inside the car (the user is present), headset206will continually attempt to reconnect to the mobile phone to which it was last connected, unless it is already connected to a mobile phone. If car charging dock204is placed in an ignition that is always powered (not dependent on a key in the ignition), and the user leaves the car parked, for example at a long term parking lot, then after 10 minutes of no vibration (the user is not present), headset206will not attempt to reconnect with the phone, thus the parasitic power draw of the wireless headset system202is reduced.

Thus wireless headset system202provides the benefit of headset206attempting to automatically reconnect with the user's mobile phone when headset206is docked on car charging dock204, and thus connected to a large power source (the car's battery), but only when vibration (i.e. presence) is detected and only if the headset is not already connected to the mobile phone. When headset206is not docked and without access to the car's battery, the reconnection function is not automatically executed, thus preserving the battery life of headset206. If the headset206is not docked, it is still possible to manually initiate a reconnection by activating the answer button on the headset. As stated above, operating button50(which toggles reconnection on-off switch92, allows the user to enable or disable automatic reconnection.FIG. 17shows that the vibration detection scheme is also used to turn LEDs76a-76hon and off. The activation of LEDs76a-76hbased on vibration sensing is preferably not de-activated when automatic reconnection on-off switch92is switched to disable reconnection.

Desk Dock

FIG. 18illustrates the implementation of the reconnection signal circuit in a desktop charging dock214that can be used in the home or office. In this embodiment, no vibration sensing is necessary because the dock is powered by AC line power. Desktop charging dock214includes a charging pedestal118that is the same shape as charging pedestal54on dock module210, and a reconnection on-off switch112that disables or enables the reconnect function. When the reconnection function is enabled, a microcontroller internal to desktop charging dock214continually toggles reconnection signal circuit so that when headset206is placed on desktop charging dock214, headset206perpetually attempts to connect to the last audio gateway (mobile phone) to which it was connected (assuming it is not already connected to an audio gateway). For this configuration, it may be desired to omit the LEDs that indicate reconnection is under way.

When the user moves out of the RF range of headset206while the headset is docked on desktop charging dock214, the connection between headset206and mobile phone is lost. When user moves within RF range of headset206docked on desktop charging dock214, headset206automatically reconnects with the user's mobile phone.

Alternate User Presence Detection Schemes

There are other techniques (other than sensing vibration) for detecting user presence that can be used to trigger reconnection. For example, instead of sensing vibration, presence can be detected by using a solid-state accelerometer connected to an analog-to-digital port on microcontroller (e.g. an ADXL203 Dual Axis Accelerometer, provided by Analog Devices, Inc. of Norwood, Mass.), which would sense movement and/or acceleration of the car (and possibly certain vibrations as well).

Another technique for detecting user presence can be a circuit for monitoring alternator noise present on the cigarette lighter power circuit. When the car engine is running there is a 60-cycle ripple present in the power system, due to the effect of the alternator. A noise sensing circuit including a filter and a trigger can detect this ripple and would be connected to an input port on a microcontroller (where firmware on the microcontroller continually monitors the port).

Yet another technique for user presence detection involves the use of a circuit connected to a microphone for sensing sound. The microphone component and an audio filter is connected to a trigger, which in turn is connected to a port on the microcontroller. The audio filter insures that only sound in a certain frequency band will activate the trigger so as to avoid needless false positive detections. Firmware in the microcontroller would always monitor the port, even during sleep mode.

Yet one more user presence technique could be a circuit that includes a low power IR detector. An IR detector connected to a filter and a trigger could be connected to a port on microcontroller. Firmware in the microcontroller always monitors the port, even during sleep mode. When a user is present, IR energy is detected, and the logic level at the trigger circuit is switched.

Thus, for any of these alternate user presence detection techniques, the vibration switch86can be replaced by the accelerometer, the power noise sensing circuit, the sound sensing microphone and related circuit, or the IR detector and related circuit described above, and/or combinations thereof.

Dash Mounting and Connection

FIG. 19andFIG. 20show how dock module210can be separate from car charging dock204, for separate location such as on a car dash. A dock module tether assembly218includes all the components in dock module210except a dock tether adapter124is used in place of dock module cover60.FIG. 20shows that dock module210includes a dash mount dock module adapter126in place of pivot plate. Dock module210is removed from car charging dock204by removing a screw that passes through access hole132and screws into screw boss130in dock module rear62. Dash mount dock module adapter126attaches to dock module210by fitting the undercut on dash mount dock module adapter126into the opening in dock module rear62and fastening the screw in screw boss130. Dock module tether assembly218includes a dash mount tether128that is a covered wire circuit bundle that brings all of the same charging, LED power, and reconnection circuit lines to dock module210. In one embodiment dock module210is mounted with the use of double-sided foam tape that is placed on the rear side of dash mount adapter126. In another embodiment dock module210is removably mounted to the dash with double-sided Velcro tape.

Referring now toFIG. 19, car charging dock204can be placed into an auxiliary 12-volt cigarette lighter power receptacle216, which is then wired to the car's 12-volt and ground circuit. Thus, car charging dock204connected to power receptacle216can be fastened underneath the dash out of sight of the user. Wireless headset206is docked to dock module210in the same way as described above. All of the charging and reconnection functions are the same as well.

In yet one more alternate embodiment shown inFIG. 21, a car charging dock220includes a remotely tethered auxiliary power receptacle222. Charging circuit in dock220includes +12 volt power and ground pass-through circuits that are connected to power cable134, which is connected to an auxiliary cigarette lighter power receptacle222, allowing other cigarette lighter charging devices, for example the user's mobile phone, to be powered while car charging dock220is place in the car's cigarette lighter.

It is to be understood that the present invention is not limited to the embodiment(s) described above and illustrated herein, but encompasses any and all variations falling within the scope of the appended claims. For example, while the present invention is described primarily in conjunction with a mobile cellular telephone serving as an audio gateway, any gateway (audio, video, data, etc.) can be used as part of the present invention. Examples of such gateways can include a mobile cellular telephone, a personal computer, an internet phone (voice over IP), etc.