GB2483308A

GB2483308A - Docking device with pickup coil coupled to electromagnetic transducer

Info

Publication number: GB2483308A
Application number: GB1014781.7A
Authority: GB
Inventors: Jack Kemp
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-09-06
Filing date: 2010-09-06
Publication date: 2012-03-07
Also published as: GB201014781D0

Abstract

Wireless multimedia docking device 100 supporting a portable audio handset 200, e.g. with a foam rubber pad (101), enabling the handset to be amplified through external speakers, without physical connection between the docking device and the handset. The device comprises pick-up coil 102 positioned to pick up fluctuations in the magnetic field of the loudspeaker 202 in the handset, amplifiers 208, 210, and contactless battery recharger (802), (803). It can comprise a radio transmitter 214, such as FM, UHF, VHF, or Bluetooth (RTM) generating a signal picked up by a receiver, e.g. car radio, to play amplified music or sound from the handset. The pick-up coil may comprise first and second coils to pick up signal from left and right speakers of the handset. The docking device can comprise a speaker for coupling with a microphone in the handset and a two-way radio transceiver for coupling between a remote transceiver, e.g. a Bluetooth (RTM) headset, and the device, and between the device and the portable handset. Physical wear on electrical connections is avoided. The docking device is compatible with products such as Apple IPod (RTM) and IPhone (RTM), most standard MP3 Players and a large range of mobile phones.

Description

t V.' INTELLECTUAL ..* PROPERTY OFFICE Application No. GB 1014781.7 RTMI Date:6 December 2010 The following terms are registered trademarks and should be read as such wherever they occur in this document: iPod, iPhone, Bluetooth Intellectual Properly Office is an operating name of the Patent Office www.ipo.gov.uk A Wireless Multimedia Docking Device and System

Field of Invention

The present invention relates to a docking device for a portable audio handset, such as a mobile telephone, MPEG player or iPodTM, and in particular to a wireless multimedia docking device and system and a kit of parts including such a device.

Background

Portable audio handset docking devices that have been made to date require a physical connection to the portable audio handset (the mobile telephone, MPEG player, iPodTM or similar device) via a data connector port which is typically located on the bottom of the handset. This data connector port is usually a unique interface only used by a certain type of handset and may not be compatible with other types. Existing docking systems are prone to mechanical failures and damage.

Summary of the Invention

The present invention provides a docking device for a portable audio handset and comprises: means for supporting the handset; a pickup coil positioned for coupling with an electromagnetic transducer in the handset; an amplifier coupled to the pickup coil; and means for conveying a signal from the amplifier to an audio output.

The present invention avoids physical wear on electrical connections by providing a wireless multimedia docking system which is compatible with products such as the Apple IP0dTM and lPhoneTM ranges, most standard MP3 Players and a large range of mobile phones. The invention enables such devices to be amplified through external speakers without any physical connection or link between the two systems.

The docking device is preferably dimensioned to support a mobile telephone handset that has a loudspeaker at one end of the handset, the docking device having a pick-up coil positioned to pick up inductive fluctuations in a magnetic field generated by the loudspeaker.

The docking device preferably has a foam rubber pad for supporting the portable handset, the pickup coil being located beneath the pad.

Brief Description of the Drawings

Specific embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which: Fig. 1 is a stereoscopic view of the complete docking device.

Fig. 2 is a side view of the docking device with a portable audio handset such as a mobile telephone or IP0dTM positioned on top, as in use.

Fig. 3 is a diagram of top, side and end views of one of the pickup coils of Fig. 2.

Fig. 4 is an end view of an alternative pickup coil.

Fig. 5 is a diagram of top, side and end views of a ceramic bar magnet of Fig. 4 Fig. 6 is a circuit diagram of one of the audio amplifiers of Fig. 2.

Fig. 7 is an exploded view illustrating an example of manufacture of the case of Fig. 1.

Fig. 8 is a schematic illustration of power saving arrangements and alternative ways of providing power to the device.

Fig. 9 is a side view and schematic of the arrangement of Fig. 1 or Fig, 8 with certain additional features.

Fig. 10 is a stereoscopic view of the device of Fig. 1 or Fig 9 with stereo coils.

Fig. 11 is a stereoscopic view of an alternative shape for the docking device.

Detailed Description of the Preferred EmbodLments

Referring to Fig. 1, an example of the docking device is shown in the form of a flat rectangular box 100, for example manufactured from white acrylic plastics material, having a foam rubber pad surface 101 and having internally at one end of the general rectangular shape a pick-up coil 102. The preferred length and width of the box are 140 mm and 83 mm respectively and the preferred depth is 17 nm', but these dimensions are not critical, provided that the general shape is configured for a portable audio handset such as a mobile telephone, MPEG player or iPodTM to be positioned on top of the box, on the rubber pad 101, with one end of the portable audio handset positioned generally over the coil 102.

The device of Fig. 1 can take other shapes, such as an oval shape, or a flat lozenge shape, or the shape of a cradle, which will house the mobile telephone or iPodTM either horizontally or in a more vertical orientation.

Fig. 2 shows the device of Fig. 1 in side view, with certain elements of circuitry inside and with a portable audio handset 200 sitting on top of the rubber pad 101. The portable audio handset has a speaker 202 that has its own magnetic coil. This is typical for most mobile telephones, iPodTM devices, MPEG audio players and the like. Almost universally, these devices have a small speaker which operates on the principle of a magnetic coil that moves a diaphragm. (There are, of course, iPodTM devices that have no speaker and rely entirely upon headphones that are plugged into the device. The docking device of the present invention is not so well adapted to these models, but can operate with such devices by placing the earphones on the pad 101.) Internal to the docking device 100 is the coil 102, which in this case can be seen to comprise first and second coils 204 and 206. These coils are connected respectively to audio amplifiers 208 and 210. The outputs of these amplifiers are connected together at node 212, where they act as the input of a radio transmitter 214 having a small antenna 216. The radio transmitter is preferably an off-the-shelf FM transmitter operating at about 87.5 MHz to 108.0 MHz at less than 50 nano-watts (-73 dBm). It has a range no greater than eight metres. The antenna 216 is preferably a simple length of wire or PCB conductive track that passes around the inside of the docking device 100.

In operation, the portable audio handset 200 is placed on the rubber pad 101 such that the speaker 202 is positioned over one or both of the coils 204, 206. As music is played from the speaker 202, fluctuations in the magnetic field generated by the coil of the speaker 202 arc picked up by the coils 204 and 206 and amplified by the amplifiers 208 and 210. The combined amplified audio signal is fed to the FM transmitter 214, which transmits an FM radio signal from the antenna 216. A signal from the FM transmitter 214 can be picked up by any domestic FM receiver, including a car radio. By this means, music or other sounds from the portable audio handset can be played out at amplified levels through a home FM radio receiver.

As an alternative to an FM transmitter, a UHF transmitter, a VHF transmitter, a Bluetooth transmitter, an infrared transmitter, or other transmitter may be used that couples to a complementary receiver connected to an audio output such as a home hi-fl player.

Details of one of the coils 204, 206 are shown in Fig. 3. Each coil is about 67 mm long, 8.5 mm wide and 15 mm deep, with a central core 1.5 mm wide and 20.5 mm deep. The DC resistance of each coil is preferably less than 4 kohm and its inductance at 1 kHz is 4.68 H. Coils of different sizes were tested and the coil described gives the preferred operating range and low noise level and spans the entire width of the pad 101, meaning that the operating range is as wide as possible, enabling the system to operate with a greater number of speaker-embedded devices. Pickups with greater and lesser inductances were tested. Those with greater inductance give a higher signal, but a greater level of noise. Pickups having between 500 and 6000 turns or ranging from about 1.5 H to 6.0 H give the preferred performance.

Several coils can be arranged side by side as shown in Fig. 4. This figure shows a three-coil assembly, with individual ceramic bar magnets positioned between the cores of adjacent coils (at the lower end). In the preferred arrangement as shown in Fig. 2, there are two such coils mounted side by side with a single ceramic bar magnet between them.

The arrangement of Fig. 2 is preferred, as it provides a good positional range for the speaker 202 of the portable audio device 200. The user can position the device on the dock without the need to accurately align the speaker 202 over a single coil. By provision of two coils, there is greater scope for horizontal changes in position. Moreover, the user can audibly hear the quality of the signal generated and can position the device optimally to provide the best pickup. This is advantageously done with two coils 204, 206, because the optimal position is a location directly over one of the coils, but the provision of two coils provides a wide range of tolerance in this position. A third coil (as shown in Fig. 4) extends the range, but adds to the weight and the cost.

S

Referring to Fig. 5, a diagram of top, side and end views of a ceramic bar magnet is shown.

each bar magnet can be about 60 mm long, 7mm wide and 3mm deep. Other geometries of the bar magnet might be used depending on design choices.

Referring to Fig. 6, a circuit diagram of the one of the amplifiers 208 and 210 is shown. It comprises the following components: Reference Number The Component Value 601 Capacitor Cl lOOnF - 602 Resistor R2 1 kohm 603 Resistor Ri 100 kohm 604 Resistork5 lO0kohm 605 CapacitorC3 lOOnF 606 Resistor R4 100 kobm 607 Capacitor C2 10 microF 608 Resistor R3 10 kohm The arrangement is such as to give an operational amplifier 609 a gain of approximately 100, so that a signal from the pickup coil 204 applied at input to capacitor 601 is amplified at the output of capacitor 607.

The amplifier 600 is one half of a pair of amplifiers on a single IC. The other amplifier of the pair is arranged in exactly the same configuration to amplify the signal from the other coil 206. The outputs of the two amplifiers are combined at point 212 in Fig. 2.

Tests show that using an iPhoneTM at half volume positioned approximately 1 mm about the pickup coils gives approximately 24 millivolts peak-to-peak input signal to the amplifier 600.

(This increases to 100 millivolts at frill volume). A preferred input range for the FM transmitter is between 2.0 and 2.5 volts. This is satisfactorily achieved with a gain of 100.

The preferred range for the gain is from about 20 to about 200.

Referring now to Fig. 7, a preferred construction for the housing of the docking device is shown. It comprises a top part 700, walls 702 and a base 704. The top part is shown as constructed in laminar form from two sheets 710 and 711, but depending on the manufacturing technique used, it can be moulded as a single piece. Similarly, the side walls are shown in laminar form from two layers 712 and 713, but these too can be moulded from a single piece and can be integral with the top part 700 or the base 704. Layer 711 of the top part 700 is shown as having cross beams 720, with holes between the cross beams. These cross beams support the rubber pad 101, which is glued to the upper face of layer 711 and fits snugly within the wall defined by layer 710. The holes between the cross beams serve to reduce weight and to reduce any barrier to magnetic coupling. Each of the layers 704 to 713 is 6 mm thick. The foam rubber pad 101 is made of foamed elastomeric material, or a material of lesser density rubber composites (open cell styrene, butadiene rubber or open cell SBR) and is about 1 mm thicker, so it protrudes slightly from the top face of the docking device. The foam rubber pad has the advantage of providing grip so that the audio handset does not slide, but remains in position with its speaker 202 correctly positioned over the pick-up coil 102.

The housing can be sealed in a number of ways. It can be manufactured in upper and lower parts that are held together by screws, or it can be manufactured as a complete sealed unit.

The battery can be changed by separating the upper and lower halves, or by removing the upper pad 101 to provide access through the holes in the upper layer 711, or (as described below) it can be permanently sealed with a battery that provides sufficient energy for the lifetime of the product.

When not in operation, the amplifiers 208 and 210 consume very little current. Their current consumption increases when an active speaker 202 is placed within range of the coils 204 and 206. The more significant current consuming component of the device is the transmitter 214.

Accordingly, in a preferred arrangement, the transmitter 214 has an "off' or "standby" mode, in which it is disconnected from the power supply except when the output of at least one of the amplifiers 208 and 210 shows fluctuations above a certain threshold, e.g. 1 volt peak-to-peak fluctuations. For these purposes, an AC threshold detector (804) is provided connected to a switch (805) on the transmitter 214 as shown in Fig.8. With such an arrangement, the device can be powered with a small battery. While the device is operating and amplifying the pickup signal, it typically consumes a current of 200mA. For example, a 9v battery with a capacity of 500-2000mAh can power the device continuously for approximately 2.5 to 10 hours. With the ability to switch the FM transmitter of the device into sleep mode and with the remaining components thawing an even smaller current, the device typically consumes a current of 8mA, so a 9v battery with a capacity of 500-2000mAh can power the device continuously for maximum 250 hours (about 10 days).

The battery is preferably and can be recharged by one of several means as shown in Fig. 8.

For example, a power inlet 800 can be provided into which an AC power adaptor can be plugged. Alternatively, contactless charging can be provided by means of an inductive coil 802 and rectifier bridge circuit 803. The contactless charging can be achieved by placing another electronic device 806 having an inductive coil 807 and AC source 808 nearby the inductive coil 802. This arrangement has the particular advantage that the device can be entirely sealed (e.g. in resin) and can be used in a variety of leisure environments such as on a beach or by a pool, without fear of damage by sand, water or the like.

In the case in which the portable audio handset is a mobile telephone, the docking device can be provided with an audio backchannel from the docking device to the portable audio handset.

This is illustrated in Fig. 9, which shows a speaker 900 mounted on the device below the rubber pad 101 at an end opposite the pick-up coil 102, Connected to the speaker 900 is an audio output circuit 901. The audio output circuit 901 and speaker 900 provide audio output to a microphone 902 in the mobile telephone at an end thereof opposite the speaker 202. In this embodiment, the transmitter in the docking device is a two-way transceiver, for example a Bluetooth transceiver, and is coupled to a speaker and microphone combination such as a headset. The arrangement can be used, for example, for hands-free mobile telephone operation, e.g. when driving.

In use, the mobile telephone is placed on the docking device in the correct orientation, with its keypad upwards. The user can dial a telephone number (before or after placing it on the docking station) and when a conversation is initiated, the user can speak into a small headset microphone and the voice is transmitter by BluetoothTM to the transceiver, played out through the speaker and picked up by the microphone for transmission. Received voice is played out through the speaker as already described, and the magnetic fluctuations of the speaker coil are picked up by the pick-up coil, amplified and transmitted by Bluetooth to the headset. The arrangement is advantageous because a mobile telephone microphone typically does not operate on an electromagnetic coil principal, so there is no interference between it and the pick-up coil. Equally, the reverse channel speaker is sufficiently remote from the pick-up coil to avoid cross-talk with the pick-up coil.

The docking device and a headset with two-way transceiver can be packaged and sold together as a kit of parts with the headset pre-tuned and pre-set to operate with the docking device.

Referring to Fig. 10, a further modification is shown in which the coil 102 is replaced by a pair of side-by-side coils for left and right audio stereo channels. Each coil has a separate amplifier and is coupled to a separate stereo channel of a FM (or other) transmitter. This arrangement is suitable for portable audio handsets that play music in stereo. The left and right channels are separately picked up, transmitted and replayed through a FM (or other) receiver.

Fig. 11 shows an alternative arrangement of the docking device. In this arrangement the device is in the shape of a vertical cradle. The portable audio handset can be placed in the cradle in a generally upright position (at a slight incline) with its speaker(s) uppermost. The pickup coil of the cradle is positioned towards the top of the back part of the cradle.

The present invention has been described with reference to preferred embodiments, it will also be appreciated by those skilled in the art will recognize that changes and modifications may be made without departing from the scope of the invention.

Claims

Claims 1. A docking device for a portable audio handset comprising: means for supporting the handset; S a pickup coil positioned for coupling with an electromagnetic transducer in the handset; an amplifier coupled to the pickup coil; and means for conveying a signal from the amplifier to an audio output.
2. The device of claim 1, wherein the means for conveying the signal comprises a radio transmitter for transmitting the signal from the device to a radio receiver.
3. The device of claim 2, wherein the radio transmitter is a FM transmitter.
4. The device of claim 2, wherein the radio transmitter is one of a UHF transmitter, a VHF transmitter, a Bluetooth transmitter and an infrared transmitter.
5. The device of any one of the preceding claims, dimensioned to support the portable audio handset having a loudspeaker at one end of the device, the docking device having a pick-up coil positioned to pick up fluctuations in a magnetic field generated by the loudspeaker.
6. The device of any one of the preceding claims wherein the pick-up coil comprises first and second coils, each extending transversely across the device in side-by-side arrangement.
7. The device of any one of the preceding claims wherein the pick-up coil comprises left and right coils for picking up signals from left and right speakers of the audio handset.
8. The device of any of the preceding claims, comprising a speaker mounted in the device at a position remote from the pick-up coil for coupling with a microphone in the audio handset.
9. The device of claim 8 comprising a two-way radio transceiver for connected to the amplifier and the speaker for two-way coupling between a remote transceiver and the docking device and between the docking device and the portable handset.
10. The device of any one of the preceding claims comprising a foam rubber pad for supporting the portable handset, the pickup coil being located beneath the pad.
11. The device of any one of the preceding claims wherein the pick-up coil has an inductance from 1.511 to 611, or has about 500 to 6000 turns.
12. The device of any one of the preceding claims, comprising a rechargeable battery and contactiess means for recharging the battery.
13 The device of claim 2 comprising: a source of power; a sensor for sensing the output of the amplifier; and switching means for selectively coupling the radio transmitter with the source of power, wherein the switching means decouple the radio transmitter from the source of power when fluctuations of the output of the amplifier sensed by the sensing means are below a predetermined threshold.
14. A kit comprising: a docking device in accordance with claim 9; and a headset with two-way transceiver, wherein the headset is pre-tuned and preset to operate with the docking device.
15. A docking device for a portable audio handset substantially as hereinbefore described with reference to, or as illustrated in Figures 1, 2, and 6 to 11 of the accompany drawings