FIELD OF THE INVENTION

The invention relates to provision of a user feedback indication for near field communications, and in particular, but not exclusively, to provision of visual user feedback indications in consumer devices and appliances.

BACKGROUND OF THE INVENTION

Near field communication is a communication technique that utilizes near field magnetic coupling to transfer data, and if necessary power, between suitably enabled devices. Specifically a Near Field Communication standard has been developed by ISO/ IEC (the International Organization for Standardization/ International Electrotechnical

Commission) to provide a two way communication technology, able to operate in one of two modes, either using peer-to-peer communication, or using an asymmetric arrangement with an active master communicating with a passive tag (similar to conventional RFID

techniques). The operating range is typically in the order of just a few centimeters.

Near field communication has been around for a number of years, and has so far mainly found application in areas such as secure payment, public transportation ticketing or for providing a means of associating (pairing) devices via the mechanism of a single touch. More recently near field communication has been gaining popularity and has started to appear in mainstream mobile phones (Smartphones). This gives owners the ability to conveniently and securely exchange data with either other suitably enabled phones, or with other items of consumer equipment with embedded near field communication capability. Because the operating range of the technology is so relatively small, it can have significant advantages over other longer range technologies. For example, communication standards such as Bluetooth require complex pairing procedures before data exchange can begin.

Although traditional close range technologies, such as RFID, tend to be used for low complexity applications, such as merely detecting an identity or presence of an RFID tag, more complex and advanced applications are possible using near field communication. One possible option is to exploit near field communication to remove the need for physical controls (e.g. switches, display indicators and connection points) from the outer casing of consumer appliances. Instead, a simple near field communication module can be hidden under the surface of the appliance and used to provide a link with an external device that can then be used to provide a user interface. This may e.g. allow consumer appliances to have a much cleaner, less cluttered exterior design. In many cases, the consumer device can be reduced in size since the user interface resides in a separate device (such as a Smartphone). The approach may in many cases reduce cost as no or reduced user input and output functionality need to be implemented in the device.

However, a significant drawback of using an external near field communication device to control e.g. an appliance is that the external device must be positioned fairly accurately for optimum operation and reliability. The user may typically be uncertain about the optimum positioning thereby resulting in a potentially degraded and less reliable service.

Furthermore, the uncertainty provides an uncomfortable and less confident user experience.

The problem may be exacerbated by the sensitivity of the magnetic coupling between near field communication enabled devices to orientation. Thus, it may not be sufficient that the user holds the external device close to the device that is being controlled, but it may also be required that the external device is oriented such that the near field communication antenna is positioned towards the controlled device.

Hence, an improved approach would be advantageous and in particular an approach allowing increased flexibility, improved reliability, facilitated implementation, an improved user experience and/or improved performance would be advantageous.

SUMMARY OF THE INVENTION

Accordingly, the Invention seeks to preferably mitigate, alleviate or eliminate one or more of the above mentioned disadvantages singly or in any combination.

According to an aspect of the invention there is provided a device comprising: a receiver for receiving instructions from an external controlling device via a near field communication link; a controller arranged to control an operation of the device in response to the instructions; a signal strength processor for determining a signal strength indication for near field communication transmissions from the controlling device by a receive antenna; a user feedback indicator; and an indication controller for changing a characteristic of a user feedback indication provided by the user feedback indicator in response to the signal strength indication. The invention may provide an improved user experience in many scenarios. In many cases, it may provide an improved and/or more reliable communication. The approach may be implemented with low complexity and may provide a cost efficient improvement.

In particular, the device may provide user feedback that assists the user in positioning the external controlling device for optimum performance. The user feedback indication may be used to guide or draw in the external device for optimum positioning. The approach may not only result in an improved positioning of the external controlling device but may also provide an improved and less uncertain user experience.

The near field communication link may typically have a range for data communication of a maximum of 20, 10 or even 5 cm. In many embodiments the range for data communication is up to around 5 cm, but the system will typically exhibit a much greater range, e.g. of up to around 20cm, for providing a user feedback indication (without being able to exchange data at the longer distances)).

The user feedback indicator may in many embodiments advantageously be a visual user feedback indicator and the user feedback indication may be a visual user feedback indication. This may provide a particularly suitable user experience and is particularly suitable for guiding the user to bring the controlling device towards the optimal position. In some embodiments, the user feedback indicator may advantageously be an audio user feedback indicator and the user feedback indication may be an audio user feedback indication.

In accordance with an optional feature of the invention, the indication controller is arranged to process the received signal strength indication to provide a gradual user feedback indication.

This may provide an improved user experience and/or improved operation in many scenarios. The gradual feedback may be a continuous feedback. For example, the characteristic may have a value which can be continuously varied and which specifically may be a continuous function of the signal strength indication of the magnetic field. In some embodiments, the signal strength indication may be a continuous value.

A gradual user feedback indication provides a non-binary indication, i.e. it provides further indications than a simple on/off indication. The gradual user feedback indication may specifically indicate a signal strength/ distance to the external controlling device having no less than five or in some cases ten different possible values. In accordance with an optional feature of the invention, the signal strength indication is a discrete indication and the indication controller is arranged to generate a gradual user feedback indication which is more gradual than the signal strength indication.

In some embodiments, the signal strength indication may be a discrete parameter which is converted into a more continuous parameter (either fully continuous or with lower resolution/more steps) than the signal strength indication. This may provide improved feedback, and thus an improved user experience/ performance. In many scenarios, the indication controller is arranged to generate a more gradual user feedback indication compared to the user feedback indication using the received signal strength indication.

The indication controller may for example apply filtering, prediction, interpolation or extrapolation to the signal strength indication values to improve performance.

In accordance with an optional feature of the invention, the device is arranged to change the user feedback indication in response to the signal strength indication for signal strengths that are insufficient for the receiver to receive the instructions.

This may in particular improve the user experience and may for example allow the user to be guided towards an optimum positioning (and orientation) of the controlling device even when the controlling device is not sufficiently close to communicate with the near field communication receiver.

In some embodiments changing the characteristic of the user feedback indication in response to the signal strength indication occurs at least at a farther range than required for receiving the instructions (i.e. for receiving data).

The user feedback may accordingly be provided (e.g. also) when the external controlling device cannot be used to control the device but with the signal strength still being detectable. This may be used to guide the user when trying to move the control device towards the optimum spot for establishing the near field communication. The approach does not require data communication between the devices to be performed, or even to be possible, for the user feedback to be provided.

In accordance with an optional feature of the invention, the signal strength processor is arranged to determine the signal strength indication to reflect a total received power in a predetermined frequency interval.

This may in particular improve the user experience and may for example allow the user to be guided towards an optimum positioning (and orientation) of the controlling device even when the controlling device is not sufficiently close to communicate with the near field communication receiver. The determination of the signal strength indication may in many embodiments be performed without any demodulation of any near field communication.

The determination of the signal strength indication may in many embodiments be performed without any signal to noise separation or differentiation within the

predetermined frequency interval.

The approach may reduce complexity of the device and may reduce cost.

The predetermined frequency interval may advantageously have a center frequency of 13.56 MHz and a bandwidth of no more than 500 kHz.

The approach may in many scenarios allow the characteristic of the user feedback indication to be changed in response to the signal strength indication for at least a range that exceeds the maximum range at which the instructions (or indeed any data) can be received.

The user feedback may accordingly be provided when the external controlling device cannot be used to control the device and can in this case provide guidance to the user seeking to establish such a control arrangement. The approach does not require data communication between the devices to be performed, or even to be possible, for the user feedback to be provided.

In accordance with an optional feature of the invention, the signal strength processor is arranged to generate the signal strength indication in response to an asymmetric smoothing of signal strength measurements.

This may provide particularly advantageous operation in many scenarios. In particular, it may provide improved performance for systems wherein the signal strength from the external controlling device varies substantially.

The inventors have in particular realized that transmissions from near field communication devices can be pulsed during certain phases, and that improved user feedback can be achieved by an asymmetric smoothing/filtering in such scenarios.

An asymmetric smoothing or filtering has different time constants for increasing and decreasing amplitudes. The time constant for increasing signal strengths may be lower than for decreasing signal strengths. In many embodiments, the time constant for decreasing amplitude may be no less than five times the time constant for increasing amplitudes.

The asymmetric smoothing may specifically be provided by a peak- ho Id or peak detection circuit. In accordance with an optional feature of the invention, the signal strength processor is arranged to generate the signal strength indication in response to a smoothing of signal strength measurements with a time constant of no less than 200 msec.

This may provide particularly advantageous operation in many scenarios. In particular, it may allow smoothing to take into account pulsed transmissions from the external controlling device. Thus, the smoothing may be designed to reflect the

characteristics of the near field communication transmissions from the external controlling device rather than to just be determined by the requirement of reducing noise to provide a sufficiently reliable estimate.

In some embodiments, the signal strength processor is arranged to generate the signal strength indication in response to a smoothing of signal strength measurements with a time constant of no less than 500 msec.

The time constant may be one time constant of an asymmetric smoothing and may specifically be the time constant for decreasing amplitude values.

In accordance with an optional feature of the invention, the device further comprises a timer and wherein the indication controller is arranged to reset the timer in response to a detection of a signal strength indication above a threshold, and to change the characteristic of the user feedback indication in response to the timer expiring.

This may provide improved operation in many embodiments, and in particular for external controlling devices using pulsed transmissions.

In accordance with an optional feature of the invention, the user feedback indicator is indicative of a position of the receive antenna.

This may allow an improved user experience and may in particular assist in the positioning of the external controlling device.

In accordance with an optional feature of the invention, the indication controller is arranged to change at least one of a light intensity and a color of the user feedback indication.

This may provide a particularly suitable user feedback.

In accordance with an optional feature of the invention, the indication controller is arranged to change the characteristic of the user feedback indication in response to an operational characteristic of the device.

This may provide improved user feedback and an improved user experience. For example, the user feedback indication may have different characteristics (e.g. color or change of color) depending on the current operational mode of the device. In accordance with an optional feature of the invention, the controller is further arranged to control the operation of the device in response to the signal strength indication.

This may provide an improved user experience and may provide for a novel and intuitive way of controlling a device.

In accordance with an optional feature of the invention, the user feedback indicator is powered by the signal received by the receive antenna.

This may in many scenarios facilitate implementation, and especially it may facilitate retrofitting of the functionality into existing devices.

In accordance with an optional feature of the invention, the indication controller is further arranged to change a further characteristic of the user feedback indication in response to a variation characteristic of the signal strength indication.

This may provide additional information to the user thereby providing an improved user experience. The variation may be a derivative, and specifically the further characteristic may be changed to reflect a sign of the derivative. The further characteristic may for example be a color (with the first characteristic being a light intensity). As an example, a user feedback indication may be provided with a light intensity indicating a distance to an optimal position, and a color indicating whether the external controlling device is being moved towards or away from the optimal position. The color could change when a preset value is reached which enables optimal data communication.

According to an aspect of the invention there is provided a method of operation for a device, the method comprising: receiving instructions from an external controlling device via a near field communication link; controlling an operation of the device in response to the instructions; determining a signal strength indication for near field communication transmissions from the controlling device by a receive antenna; and changing a characteristic of a user feedback indication in response to the signal strength indication.

These and other aspects, features and advantages of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described, by way of example only, with reference to the drawings, in which

Fig. 1 illustrates an example of a control system in accordance with some embodiments of the invention; Fig. 2 illustrates an example of a possible use of a control system in accordance with some embodiments of the invention;

Fig. 3 illustrates an example of a visual indicator for a control system in accordance with some embodiments of the invention;

Figs. 4 and 5 illustrate examples of induced voltage in a near field communication antenna;

Fig. 6 illustrates an example of a driving of a visual indicator for a control system in accordance with some embodiments of the invention;

Fig. 7 illustrates an example of pulsed near field communication transmissions in a control system in accordance with some embodiments of the invention; and

Fig. 8 illustrates an example of an analog peak-hold circuit for a control system in accordance with some embodiments of the invention;

DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION

The following description will focus on embodiments wherein a visual user feedback indication is provided to assist a user. However, it will be appreciated that the invention is not limited to such embodiments but may apply to many other embodiments. In particular, in some embodiments the user feedback indication may alternatively or additionally be an audio user feedback indication.

Fig. 1 illustrates an example of a system wherein one device is controlled by another device via a Near Field Communication (NFC) link. In the example a first device, henceforth referred to as the controlled device 101, is controlled by instructions

communicated to it over a near field communication link from an external controlling device, henceforth referred to as a controlling device 103.

The controlled device 101 may specifically be a consumer electronics device, such as a television, audio amplifier, DVD player, radio etc., or may e.g. be a consumer appliance, such as a coffee machine, dishwasher, cooker, refrigerator, washing machine, electric toothbrush, other appliances like home healthcare device, like CPAP, Blood pressure and professional healthcare devices like intensive care and patient care equipment or consumer and professional lighting systems, etc. The controlling device 103 may typically be a mobile phone (Smartphone), tablet or other portable (typically handheld) device.

The controlled device 101 comprises an NFC antenna 105 which is tuned to the frequency range for NFC transmissions from the controlling device 103. In typical applications, the NFC antenna 105 is a planer helical antenna construction tuned to an approximate frequency of 13.56 MHz.

The NFC antenna 105 is coupled to an NFC receiver 107 which is fed the received signals from the NFC antenna 105. The NFC receiver 107 is arranged to receive NFC data transmissions from the controlling device 103 and accordingly comprises functionality for demodulating and decoding the received NFC signals to provide the data communicated from the controlling device 103. The NFC receiver 107 is coupled to a device controller 109 which controls the operation of the controlled device 101. The device controller 109 receives the data extracted by the NFC receiver 107 and is able to process this data as appropriate.

In the system, the controlling device 103 uses the NFC transmissions to transmit control instructions to the controlled device 101. The data provided to the device controller 109 accordingly corresponds to control instructions which are interpreted by the device controller 109. The device controller 109 then controls the operation of the controlled device 101 in accordance with the received instructions. The operations that are controlled include functions that are not part of the NFC receiving (or of the driving of the visual user feedback indicator to be described).

It will be appreciated that in some embodiments, the controlled device 101 may also communicate data to the controlling device 103. This communication may also be via NFC communication, and specifically the established NFC communication link may be a bidirectional link. Thus, the controlled device 101 may comprise an NFC transmitter for modulating and transmitting data to the controlling device 103 in accordance with the NFC specifications. Similarly, the controlling device 103 may comprise an NFC receiver for demodulating the NFC transmissions from the controlled device 101.

In the system, a consumer device or appliance may accordingly be controlled by an external device using NFC communications. Indeed, the external device 103 may e.g. provide a user interface, and in many scenarios the only user interface, to the consumer device/appliance. As a specific example, a device, such as a coffee machine or an AV receiver, can be controlled from an NFC equipped Smartphone when this is positioned sufficiently close to the device.

Such an approach may e.g. remove the need for physical controls (e.g.

switches, display indicators and connection points) from the outer casing of consumer appliances. Instead, a simple NFC communication module can be hidden under the surface of the appliance, and this can provide the primary (or only) control interface into and out of the product. In addition, the control can be provided by a portable NFC enabled device which may e.g. be a multifunction device that can also be used for controlling other devices (when being brought into close proximity of these devices) or indeed provide other functions. For example, a Smartphone which is typically always carried by a user may be used to control appliances simply by bringing them close to the appliance to be controlled. Indeed, bringing the Smartphone close to a device may be the only operation required to establish the connection between the Smartphone and the device.

It may also automatically result in the appropriate user interface application being initialized on the Smartphone. E.g. when a user touches a suitably equipped coffee machine with the Smartphone, the application for controlling the coffee machine may be automatically initialized resulting in the display showing the appropriate user interface. The user then controls the device through this user interface. When the Smartphone is removed, the application is automatically terminated. If the Smartphone is then brought next to a cooking device, the cooking device user interface may automatically appear on the display, thereby allowing the user to control the cooking device using the same Smartphone.

Such an approach may allow consumer appliances to be more aesthetically pleasing by allowing them to have a much cleaner, less cluttered exterior design. As another example, the appliances may be reduced in size, since the user interface now resides in a separate device. This may also reduce complexity and cost of the appliance. Furthermore, it may provide additional flexibility as the user interface can be easily changed or adapted when being provided by e.g. a Smartphone.

In the system of Fig. 1, the user interface of the controlled device 101 is specifically provided by the controlling device 103. Thus, the user may use a user interface of the controlling device 103 to input commands. The controlling device 103 converts this into suitable instructions that are communicated as appropriate data over a NFC communication link. The transmissions are received by the NFC antenna 105 and demodulated by the NFC receiver 107. The demodulated data is fed to the device controller 109 which proceeds to control the controlled device 101 to operate in accordance with the instructions represented by this data.

However, in order to have a reliable control link the NFC communication link requires that the distance between the controlled device 101 and the controlling device 103 is sufficiently small. Indeed, in many scenarios, it is preferred that the distance between the transmitting antenna of the controlling device 103 and the NFC antenna 105 of the controlled device 101 is only a couple of centimeters. This results in quite strict requirements for the manual positioning of the controlling device 103 by the user. Furthermore, the positioning may often be complicated by uncertainty of the user about exactly where the NFC antenna 105 is positioned in the controlled device 101, and indeed about where the transmitting antenna of the controlling device 103 is positioned. Typically, this transmitting antenna may be at one end of the controlling device 103 and therefore the orientation of the controlling device 103 also becomes important.

Indeed, one of the main drawbacks of using an external device as the user interface to a fixed appliance is that it may not always be obvious to the user where the "sweet spot" is located on the appliance, i.e. where the NFC link can be reliably established. Also, due to the sensitivity of the magnetic coupling between NFC enabled devices to the orientation of the controlling device and the relative orientations of the antennae, the user may not hold/position the controlling device optimally resulting in reduced reliability of the NFC communication link.

In the system of Fig. 1, the controlled device 101 comprises functionality which provides guidance to the user when positioning (including orientating) the controlling device 103 such that it can control the controlled device 101. Specifically, the controlled device 101 comprises a user feedback indicator, which provides feedback to the user on the positioning of the controlling device 103. The following description focusses on an example where the user feedback indicator is a visual user feedback indicator, and it will henceforth for brevity be referred to as the visual indicator 111.

In the example of Fig. 1, the controlled device 101 specifically provides a visual user feedback indication which reflects the distance to the controlling device 103. The visual user feedback is generated in response to the signal strength of NFC transmissions and may accordingly reflect how well coupled the transmitting antenna of the controlling device 103 and the NFC antenna 105 of the controlled device 101 are. Furthermore, in the example, the user feedback reflects this coupling even at coupling strengths that do not allow any NFC communication link to be established or any data to be communicated between the controlled device 101 and the controlling device 103.

In the example of Fig. 1, the NFC antenna 105 is further coupled to a signal strength processor 113 which receives the received signal from the NFC antenna 105. The signal strength processor 113 is arranged to generate a signal strength indication for the NFC transmissions from the controlling device 103.

The signal strength processor 113 is further coupled to an indication controller 115 which is further coupled to the visual indicator 111. The indication controller 115 is arranged to control a characteristic of the visual user feedback indication provided by the visual indicator 111 in response to the signal strength indication received from the signal strength processor 113.

In the specific example, the visual indicator 111 is a single light source, such as e.g. a LED or a lamp, and the characteristic being controlled is the light intensity of the light source. Specifically, the light output intensity of the visual indicator 111 may be a monotonic function of the signal strength (as reflected by the signal strength indication). Thus, as the controlling device 103 is gradually brought closer to the NFC antenna 105, the signal strength increases and the light intensity increases. Similarly, as the controlling device 103 is gradually removed from the NFC antenna 105, the signal strength decreases and the light intensity accordingly also decreases. The single light source accordingly provides a visual guide allowing the user to accurately and securely optimize the position of the controlling device 103 relative to the NFC antenna 105.

In other embodiments, the characteristic being modified according to the signal strength indication may for example be a color of the single light source. E.g. as the controlling device 103 is brought closer to the NFC antenna 105, the light may gradually change from red to green. It will be appreciated that in some embodiments, the characteristic may be a composite characteristic. For example, both color and intensity may be adjusted.

The approach can according help guide the user when trying to establish an NFC link between the controlling device 103 and the controlled device 101 , such as e.g. between an NFC enabled handheld device and an appliance. The visual indicator 111 may indicate to the user where the intended touch spot is on the controlled device 101. Indeed, the approach may provide a gradual feedback to the user indicating if he is pointing/ touching in the right direction.

The visual feedback can increase the confidence level of the user that he/she is taking the right action. By seeing the light feedback level increased, the user confidence becomes higher that he/she can indeed communicate with the appliance. The approach also helps the user to instinctively hold the device in the right orientation for effective

communication (e.g. the user may wiggle the smartphone to get the optimal position as indicated by the visual feedback).

The approach may further include an indication of when the controlling device 103 is within a range that allows the establishment of an NFC link and data transfer between the devices. This may for example be indicated by the color of the visual indicator 111 changing. This indication may for example be determined in response to a detection of the signal strength reaching a threshold, or more accurately by detecting that data is successfully demodulated.

In some embodiments, the visual user feedback indicator may be indicative of a position of the NFC antenna 105 and specifically may be positioned proximal to the NFC antenna 105. Thus, the visual indicator 109 can be positioned at the optimal NFC point (i.e. closest to the NFC antenna 105) and thus the mere position of the indicator provides guidance to the user which is then further supplemented and nuanced by the adaptation of the visual appearance of the visual indicator 109 depending on the signal strength indication. In some embodiments, the visual indicator 109 may e.g. merely be a light whereas in other embodiments the visual indicator 109 may be formed to provide a graphical representation, such as for example a logo for NFC or a proprietary logo indicating the remote control functionality.

The user experience that can be provided may be illustrated by Fig. 2. The user may hold an NFC equipped Smartphone close to a device, such as the espresso machine of the specific example. As the device is moved towards the product, and specifically towards the logo indicating the NFC remote control functionality (in the present case denoted by the term "Touch Here"), the logo (or part of it) lights up and the light intensity increases as the Smartphone is moved towards the optimal position. As indicated in Fig. 3, the logo may be, or comprise, a light emitting object that changes characteristics depending on the detected signal strength. It will be appreciated that the logo of course could have many different forms. E.g. a circular or other shaped light guide could be provided around the optimal position for the establishing the NFC link (i.e. the point that should be touched by the controlling device 103).

In the example of Fig. 1, the NFC receiver 107 and the signal strength processor 113 are shown as two separate functional identities which are both coupled to the NFC antenna 105. However, it will be appreciated that in many embodiments the two functions may be combined. For example, in many scenarios the NFC receiver 107 may generate a signal strength estimate as part of the process of (trying to) receive NFC

communications. In some embodiments, the signal strength processor 113 may receive the input signal from the NFC receiver 107. For example, the NFC receiver 107 may

downconvert the received signal to an Intermediate Frequency (IF), and the signal strength processor 113 may be fed the IF signal from which the signal strength indication is generated.

In other embodiments, the NFC receiver 107 and the signal strength processor 113 may receive signals from two different antennas, i.e. the signal strength estimate may be generated from a second NFC antenna. In such a case, the two antennas will generally be positioned in close proximity (less than say 2 cm apart). Indeed, in many embodiments, two such antennas may be positioned within each other, such as e.g. concentrically within each other.

In some embodiments, all functionality of the controlled device 101 is powered from the same power source, such as an external power source or batteries.

However, in some embodiments, some (or possibly all) of the functionality may be powered from the NFC signal received by the NFC antenna 105. Specifically, the visual indicator 109 can in some embodiments be powered by the signal received by the NFC antenna 105. This will allow the user feedback guidance to be active without requiring any additional power source.

As a specific example, the controlled device 101 may typically be in a power down mode where no power is provided to any functionality. The controlled device 101 may in such scenarios wake up and be powered when the signal strength exceeds a threshold sufficient to allow NFC data communications. However, by powering the visual indicator 109 from the received NFC signal it is possible for this to provide the user guidance before the signal strength is sufficient to support data communication. Indeed, the visual indicator 109 may be used to guide the user to the specific point where NFC data communication is actually possible.

Near field communication denotes communication that uses magnetic induction between two antennas located within each other's near field, effectively forming an air-core transformer. The communication is a short range communication wherein the maximum range at which data can be communicated is restricted to short distances. The maximum range for a near field communication system may typically be no more than 20 cm, 10 cm or even 5 cm.

A specific NFC communication standard has been developed by ISO/IEC to allow communication between devices over distances of typically only a couple of centimeters and with a typical maximum range of no more than 10 cm. The communication may be a master/slave configuration, or may in many scenarios and embodiments be a peer- to-peer communication. NFC allows a relatively high data rate of up to 424kbits/s. The NFC standard encompasses the conventional RFID technology wherein passive RFID tags can be read by external RFID readers being brought into close proximity with the tags.

NFC is designed to provide very short range communication between devices and unlike other wireless connectivity standards it is only able to transfer data when within a very close proximity (typically less than 10cm) of another NFC device Accordingly NFC provides a number of distinct advantages over conventional data communication approaches, including:

Intuitive connections to other devices as the act of bringing devices together not only enables the connection but also makes it clear which two devices are connected.

Increased security and privacy as the other connected device must be in close proximity.

It enables two active NFC devices to communicate with each other.

It enables an active NFC device to communicate with multiple passive RFID tags at the same time.

It enables an active NFC device to communicate with NFC devices that are not powered but which emulate an RFID tag when in a passive state.

For NFC, communication may be established as peer-to-peer communication or may be established with one device being the dominant active master device and the other being the passive slave device. Such communication is in particular used for RFID tags where an NFC communication device may establish contact and receive data transmitted from the tag in response to the signal from the NFC communication device.

For peer-to-peer communication, both the external controller 103 and the controlled device 101 need to be powered. Both sides can take the initiative to initiate communication and become master of the system. However, the visual indicator 111 might show the signal availability even before the peer-to-peer mode for communication has been established.

Detailed definitions of NFC can be found ISO/IEC 18092, ISO 18000-3, NFC tag type 1 , 2 and 4 in ISO 14443 -A/B and NFC tag type 3 in JIS X 6319-4 together with the NFC Forum™ standards like the NFC Forum NFC Activity Specification NFCForum-TS- Activity-1.0 amongst others.

In the example of Fig. 1, the indication controller 115 is arranged to drive the visual indicator 111 to provide a gradual visual indication. Thus, the visual indicator 111 provides more than two values, i.e. it is not a mere binary indication, but rather provides an indication that reflects the actual distance. In some embodiments, the gradual indication may be a fully continuous rather than a discrete indication. In some embodiments, the visual indication may be discrete to some extent but will typically have no less than five or advantageously in many scenarios ten levels. In most embodiments, a discrete visual indication will have sufficiently small steps for the discrete visual indication to be perceived as substantially continuous by the (casual) user.

Thus, the visual indicator 111 does not merely provide an indication of whether the controlling device 103 is within range of the controlled device 101 or not, but rather provides a visual indication that reflects the actual distance, and specifically which varies as a function of distance. This provides increased user guidance which not only informs the user of when communication is possible but also assists him in moving the device towards the optimum spot in order to allow communication.

In some embodiments, the signal strength indication may be a discrete indication having a first number of possible levels. For example, the signal strength indication may be represented by a low number of bits, such as e.g. three bits corresponding to eight possible levels.

In such cases, the indication controller 115 may be arranged to generate a more gradual visual user feedback than provided by the signal strength indication. Thus, the system may provide more gradual user feedback indication compared to the user feedback indication resulting from directly using the received signal strength indication. The visual feedback indication may thus have more levels than provided for the signal strength indication. This may provide an improved user feedback and an improved user experience.

The indication controller 115 may for example achieve this by a filtering or prediction being applied to the signal strength indication. The signal strength indication may e.g. be fed to a prediction filter which is operated with a lower quantization and longer word lengths than provided for the signal strength indication. The filter may be an adaptive filter with filter coefficients that are continuously adapted (e.g. using Minimum Square Error adaptation techniques as will be known to the skilled person).

In the system of Fig. 1, the controlled device 101 is arranged to provide a visual feedback indication indicative of the signal strength/ distance when the signal strengths are insufficient to allow for the instructions from the external device 115 to be decoded. Thus, even at times where the NFC receiver 107 is not able to demodulate data received from the controlling device 103, the controlled device 101 is still able to provide a visual feedback indication that varies as a function of the signal strength indication. In particular, the light intensity of the visual indicator 1 11 may vary depending on the distance even when the signal strength is so low (and the distance to the controlling device 103 is so high) that no NFC data can be demodulated. Thus, the changing of the characteristic of the visual user feedback indication in response to the signal strength indication occurs at least for a range that exceeds the range in which the instructions can be received.

This may in particular be achieved by the signal strength processor 113 determining the signal strength indication without requiring any demodulation or decoding of any NFC communications (at least for some of the time, and in particular at least when such demodulation/ decoding is not possible).

In many embodiments, the signal strength processor 113 may determine the signal strength indication to reflect a total received power in a predetermined frequency interval. Specifically, the signal strength processor 113 may apply a band pass filter to the signal received from the NFC antenna 105. The signal energy of the resulting output may then be estimated (e.g. by rectification and low pass filtering) and used as a signal strength indication.

Thus, in such embodiments, no demodulation is needed but rather a low complexity determination of signal energy in a frequency interval is measured. The frequency interval is selected to correspond to the frequency interval in which NFC communications are performed, and is typically set to have a center frequency of around 13.56 MHz and a bandwidth of around 500 kHz. A rectification and low pass filtering of the output of the filter provides a signal that slowly varies in line with the signal energy in the frequency interval, and this provides a good indication of the signal strength for NFC transmissions. In particular, if there are no NFC devices transmitting in the immediate vicinity, the signal energy will be measured at a low level corresponding to the amount of noise and interference in the frequency interval. If a transmitting (scanning) NFC device approaches, the signal will gradually increase as the signal energy in the frequency interval rises. This increase can be detected even at low levels, and specifically at levels that do not allow demodulation. Accordingly, as the controlling device 103 approaches the NFC antenna 105, the visual indicator 109 will increase in brightness to reflect the increased signal energy in the measured frequency interval. At some stage, the controlling device 103 may be sufficiently close to allow data to be demodulated. The signal strength processor 113 may proceed to determine the signal strength indication based simply on the energy level in the frequency interval, and thus the intensity of the visual indicator 109 may continue to be set according to the same criterion (and thus without any perceived discontinuity). However, in addition, when demodulation is possible, the color of the visual indicator 109 may change to reflect that the controlling device 103 can now be used to control the controlled device 101. Such an approach may allow both low complexity and a very advantageous user experience where the user is guided towards the optimum positioning of the controlling device 103 relative to the NFC antenna 105.

It is also noted that the approach does not separate between noise, interference and NFC signal energy. However, due to the low distances involved, the NFC signal energy is typically substantially higher than noise and interference and therefore no separation is normally required. Furthermore, in some embodiments the system may compensate for noise and interference, e.g. by having a suitably set threshold before any visual feedback is given (e.g. before the visual indicator 111 begins to light up). Such compensation may in some embodiments be adaptive, e.g. the threshold may be set to exceed a 95% percentile value for the measured signal energy for times when the controlled device 101 is not being controlled by an external device.

In more detail it is noted that for a conventional arrangement wherein an NFC device is used to read a passive RFID tag, the NFC reader generates a magnetic field (typically operating at the standardized frequency of 13.56MHz) that induces a voltage into the passive tag coil. This magnetically coupled interaction is similar to the way that a transformer operates, coupling primary coil to secondary coil. The passive tag coil in this example is usually bonded directly to the pads on an integrated circuit, which in turn, is capable of rectifying the received 13.56MHz magnetic field to provide power for its own internal circuitry (hence the ability to operate without a power source). This same 13.56MHz magnetic field can also be amplitude modulated to carry data from the reader to the tag (and from tag to reader by the known technique of load modulation).

In order for the integrated circuit in the passive tag to function correctly, a minimum voltage level needs to be present on the pads of the integrated circuit. This is derived from the magnetic field coming from the NFC module. This minimum activation voltage for this integrated circuit can vary from manufacturer to manufacturer, but a typical activation voltage is in the order of 4V. The passive tag coil voltage is largely dependent upon the mutual inductance between itself and the NFC coil it is magnetically coupled to. This mutual inductance is itself a function of both coil geometries and the spacing between them.

From the standard, generalized expressions available for induced voltages in tuned loops, the magnetic B-field necessary to generate the 4Vp-p required on the passive tag integrated circuit pads can be calculated: B ₀ =

2nfNSQ cos a

Where:

Vo = Induced rms voltage on passive tag coil (from NFC reader) f=operating frequency

- N=Number of turns in passive tag coil

S=Area enclosed by the passive tag coil

a= Angle of arrival of the magnetic field from the NFC reader (a=0° means that the NFC coil and the passive tag coil are parallel - the optimum case) Assuming the following typical values:

Minimum induced voltage Vo=(4V x 0.7071)

f=13.56MHz

N=4 (typical)

S=0.0046224m ² (standard ISO card coil area)

- Q=35 (typical target coil design value)

a=0° (optimum orientation),

the required B-field from the NFC reader can be determined as:

4/V2

^Bo = In - 13.56 X 10- . 4 - 0.0046224 - 35 - cos 0° = ^{5 " 13 X 10~8 wbm~2}

The current required in the NFC device coil to generate this magnetic field can then be calculated. This is a function of the separation distance between NFC device coil and passive tag coil. Again, the standard equation that describes the magnetic field produced by a circular loop antenna can be used:

_ μ ₀ ΙΝα ²

B _Q -

₂ ( _a 2 _{+ r} 2 ) 3/2 where:

μo=Permeability of free space (4π x 10 ^"7 mFT ¹ )

I=NFC coil current (rms) N=Number of NFC coil turns

a=NFC coil radius

r=Separation distance between NFC coil and passive tag coil Re-arranging to obtain the NFC reader coil current, yields:

2B ₀ (a ² + r ² ) ^3/2

I _rr

Νμ ₀ α ²

Using the required minimum B-field value from above (5.13 x 10 ^"8 wbm ^"2 ), plus the following assumptions about the NFC reader coil geometry, a value for the minimum required NFC coil current in a typical use case (e.g. with 4cm read/write range) can be determined:

Assumptions:

N=6 (typical value of NFC coils)

a=2xl0 ^"2 m (typical value of NFC coils)

r=4xl0 ^~2 m (4cm is a typical maximum read/write range between NFC devices and passive tags)

Therefore current is as follows:

2 ^■ 5.13 x lO ^-8■ ((2 x 10 ^~2 ) ² + (4 x lO ^-2 ) ² ) ³ / ²

/ _{= =} . OA rn A

6 · 4π χ 10- ^7■ (4 x 10 ^"2 ) ²

Thus, for a 4cm read/write range, a 3.04mA current is required in the NFC reader energizing coil. The controlling device 103 can be assumed to operate with operating characteristics similar to those determined above. However, it is now desired the visual indication is provided for the same operating characteristics for the controlling device 103 but at substantially further distances.

Thus, the signal strength processor 113, indication controller 115 and visual indicator 109 should operate with received voltages that are below the full activation voltage required by a passive tag. This is in particular possible as this operation does not require any exchange of data but only an indication of proximity of the controlling device 103. The induced voltage for difference distances can be calculated from the provided equations and are illustrated in Figs. 4 and 5 (in Volts and dBV respectively, i.e. linearly and logarithmically).

A possible low complexity approach for controlling a visual indicator 111 is illustrated in Fig. 6. In the example, the NFC antenna 105 is coupled to a differential voltage amplifier 601 which amplifies the received signal level to a suitable value (e.g. for driving a LED). The resulting signal is rectified by a rectifier 603, which in some examples may be a single diode. The resulting rectified voltage is then low pass filtered by a low pass filter 605 to generate a slowly varying signal representing the received signal level. This signal can directly be used to drive a LED implementing the visual indicator 111. The circuitry may e.g. be powered from a battery or other power source 607.

It should be noted that the approach measures the signal energy in a frequency interval despite not incorporating any specific filter in the signal path. This is due to the use of a tuned antenna which is tuned to the NFC frequency interval and which accordingly is frequency selective. It should also be noted that the exact mapping between the functionality of the functional blocks of Fig. 6 and the signal strength processor 113 and indication controller 115 of Fig. 1 may be done in different equivalent ways. For example, the differential voltage amplifier 601, the rectifier 603, and the low pass filter 605 may be considered part of the signal strength processor 113 or part of the indication controller 115, or may be considered to be distributed between these.

The approach thus provides a range for the visual indication which exceeds the range for data communication. The exact range which is preferred for both data

communications and visual indications may depend on the characteristics and preferences of the individual embodiment. The following table provides indications of ranges that may be particularly suitable for various embodiments depending on how optimized the specific implementation is required to be:

Excellent Reasonable Minimum

Data communication 1-3 cm 4-6 cm 7-10 cm

range

Visual indication 1-9 cm 10-18 cm 19-30cm

Range The visual indication range preferably exceeds the data communication range. In many embodiments, the visual indication range is no less than twice the data

communication range, and in many embodiments it is advantageously no less than 3, 5 or even 10 times larger.

In some embodiments, the signal strength processor 113 is arranged to generate the signal strength indication in response to an asymmetric smoothing of signal strength measurements. The asymmetric smoothing may be an asymmetric filtering, such as e.g. a peak and hold circuit. The asymmetric smoothing is such that the time constant is different for increasing signal strength than for decreasing signal strength, and typically the time constant for decreasing signal strength is higher than for increasing signal strength.

Thus, in many embodiments, the signal strength indication changes substantially quicker to reflect increasing signal strengths than it does to reflect decreasing signal strengths.

Such an approach may provide an improved user experience in many scenarios, and may in particular focus on providing fast indications and feedback for the process of the user moving the controlling device 103 towards the controlled device 101 to establish contact.

In particular, the Inventors have realized that providing an asymmetric smoothing provides an improved visual user feedback while allowing a pulsed NFC transmission from the controlling device 103. Indeed, the Inventors have realized that despite pulsed transmissions not being described in the NFC standard, the visual user feedback indication can be used with such pulsed transmissions by introducing asymmetric smoothing.

Fig. 7 illustrates an example of a pulsed NFC transmission that may e.g. be provided by a Smartphone when scanning for other NFC devices in order to reduce power consumption.

Determining the signal strength indication such that it simply corresponds to the signal level for would for such pulsed transmissions result in a pulsed (blinking) visual indication which is likely to be considered suboptimal by the user. One option is to filter the signal strength indication to provide a low pass (e.g. moving average) signal strength indication that results in a more constant light. However, in many scenarios, the distance between pulses may be in the order of up to a second. This will result in very slow feedback to the user which will reduce the benefit of the visual indication. In particular, when bringing a controlling device 103 towards a controlled device 101, the slow response will reduce the effectiveness of the user feedback. In such scenarios, the application of an asymmetric smoothing may improve performance and in particular provide an improved user experience.

In particular, the signal strength indication may be generated using a peak hold arrangement with a fast rise time, but slow decay time. Including such a peak-hold circuit (which has a short time constant for rising signals, but a long time constant for falling signals) can result in the pulsing effect largely being mitigated.

When choosing the time constants, a balance has to be struck between making the visual feedback indication as constant as possible, while at the same time allowing the indicator to be as responsive as possible. It has been found that particular advantageous performance is often found for a time constant of no less than 500 msec. In case of two time constants (i.e. asymmetric smoothing), the longest time constant is in many embodiments advantageously no less than 500 msec, whereas the other time constant (typically for rising signal strengths) may be substantially shorter.

An example of an analog peak-hold circuit is illustrated in Fig. 8. In the diagram, the source "VI" represents the rectified 13.56MHz signal envelope from a preceding circuit arrangement. The short time constant (increasing signal strengths) is formed by R2 (800Ω) and CI (2.2μΡ) when the diode D3 is forward biased, while the long time constant (decreasing time constants) is formed by R3 (3ΜΩ) and CI (2.2μΡ) when the diode is reversed biased. Fig. 7 also shows the resulting smoothed output that is used to provide the visual indication (the dotted line).

It will be appreciated that other approaches can be used. For example, improvements in performance (constant light output versus responsiveness) may be achieved by implementing the smoothing function using a simple, low cost microcontroller. One possible example might be the Microchip PIC12F683 8-pin microcontroller. The advantage of this device is that it already contains a 10 bit A/D converter and hardware PWM output.

Of course, in many circumstances where a host processor is included in the application itself, it might be even more convenient and cost effective to use this processor to also provide the asymmetric smoothing.

In other embodiments more complex approaches may be used to provide a more constant light output for pulsed transmissions. For example, in some embodiments, some pulsed transmissions may be very short and may not be detected in a filtered approach.

In some embodiments, such pulses may however be detected and the signal strength may be used to control the visual feedback. As an example, in some embodiments, the controlled device 101 may comprise a timer which is reset whenever it is detected that the signal strength indication exceeds a given timer. Furthermore, when the timer expires (e.g. reaches a preset value for an up-counting timer or zero for a down-counting timer), the controlled device 101 in response changes a characteristics of the visual indicator 111. For example, the visual indicator 111 may be changed to indicate a lower value of signal strength only when the timer expires. In this case, very short pulsed transmissions are sufficient to avoid the visual indicator 111 indicating an absence of the controlling device 103.

Also heuristics can be built-in to deal with various characteristics of NFC pulsed transmissions of smartphones and tablets. Furthermore adaptive learning algorithms can be applied. A particular pattern can be recognized and a smoothing filter can be applied.

In the previous embodiments, the visual indicator 111 is driven so that it provides an indication of the signal strength level, and thus of the distance to the controlling device 103. In some embodiments, the indication controller 115 may further drive the visual indicator 111 such that another characteristic provides an indication of a variation of the signal strength indication. This variation may for example be a degree of variation, i.e.

whether the signal strength indication changes a lot/ rapidly or whether it is relatively constant/ slow moving. As another example, the indication controller 115 may drive the visual indicator 111 to provide an indication of the degree of change of the signal strength indication. Specifically, the visual indicator 111 may be driven to reflect the sign of the derivative of the signal strength indication with respect to time. Thus, the visual indicator 111 may be driven to indicate whether the signal strength indication increases or decreases. This may provide an indication of the whether the controlling device 103 is moved towards or away from the desired operational point. The second characteristic may for example be a color of the visual user feedback indication.

Thus, as an example, the visual indicator 109 may be green when the controlling device 103 moves towards the optimal position (signal strength increases) and red when it moves away (signal strength decreases). At the same time, the brightness of the visual indicator 109 can be given by the absolute signal strength, i.e. it reflects how close the controlling device 103 is to the NFC antenna 105. The approach may thus provide a very intuitive and precise guidance for the user when positioning the controlling device 103.

In some embodiments, the visual indicator 111 may furthermore be used to provide additional information to a user. In particular, in some embodiments, the indication controller 115 is arranged to change a characteristic of the visual user feedback indication in response to an operational characteristic of the device. For example, the color of the visual indicator 111 may be adapted to reflect the current operational mode of the device, such as whether a washing machine is in standby, is performing a prewash, is performing a spin operation etc. As another example, the color or e.g. graphical representation may be changed to indicate a current operational setting, such as which input is selected on an amplifier, the program selected on a coffee maker etc.

As another example, the color may be changed to indicate the availability of device data in the controlled device. As such the attention of the user might be raised for a possible maintenance task, the need for a replacement part, etc.

Thus, the visual indication can be driven to reflect the specific purpose of the appliance at the moment of interaction. The specific feedback colors can e.g. be adapted to the intended action, the specific category of the appliance and the neighborhood of the interaction device.

In some embodiments, the device controller 109 is further arranged to control the operation of the controlled device 101 in response to the signal strength indication. Thus, operation of the controlled device 101 (not related to the visual indicator 111 or the receiving of the NFC data) may be modified depending on the signal strength indication. For example, the signal strength indication value when a message is received from the controlling device 103 may be used to set a value for an operating parameter of the controlled device 101.

As a specific example, if the controlled device 101 is an amplifier, the volume of the amplifier may be set to reflect the signal strength indication when a message is received which indicates that a user input has been provided to the controlling device 103. The signal strength indication at the time of activation is accordingly used to set the volume level. This may allow a very user friendly control of the amplifier where the user merely moves the controlling device 103 towards the amplifier resulting in the volume increasing and decreasing to reflect the distance. When the desired volume is reached, the user presses a button and the amplifier then proceeds to maintain this volume level. The operation is furthermore assisted by the visual indicator 111 reflecting the signal strength indication, and thus the volume level.

In the previous examples, the user feedback indicator is a visual user feedback indicator. This is particularly advantageous in many applications and scenarios as it allows a very user friendly and accurate feedback. Furthermore, it allows for a very precise feedback that can easily be perceived. It may also allow a more complicated user feedback, e.g. with changing graphic symbols or both light intensity and color variations. However, in other embodiments other user feedback indicators may be used. For example, in some embodiments the visual indicator 111 may be replaced by an audio output indicator, for example for a visual impaired person. Similar to the varying light indicator, the system can provide a varying output depending on the signal strength but rather than (or indeed as well as in some embodiments) a visual output, the output will be a varying sound. E.g. an increase in sound pitch or sound volume can indicate that the controlling device 103 is approaching, and a decrease of sound pitch or sound volume can indicate that the controlling device 103 is moving farther away. A particular sound pitch can be activated when the controlling device is within range for data communication.

It will be appreciated that in some embodiments at least part of the controlled device 101 may be switched off when the instructions are received. In particular, at least some of the functionality controlled in response to the instructions may be off when the instructions are received. This may e.g. allow the device to be programmed to perform a specific function during a standby phase. When the device is then powered on, it may proceed to operate in accordance with the received instructions.

In such embodiments, the device may for example be completely or substantially powered on except for the circuitry required for executing the NFC

communication and providing the user feedback indication. This power may for example be provided from a main power supply or may e.g. be provided by a local and possibly short term energy store (such as a battery or capacitor) which is charged during normal operation. In some embodiments, the power may even be provided by the NFC field generated by the controlling device (103).

For example, a washing machine may be switched off. The user may enter a series of settings for a washing program using an Application on his Smartphone when away from the washing program. He may then touch his Smartphone on the washing machine (as guided by the user feedback indicator) while this is still switched off. The NFC functionality may be powered to receive the instructions and may store these instructions (specifically it may store the instructions for washing machine program). When the washing machine is then switched on, it can proceed to execute a washing sequence in accordance with the received instructions. As another example, a frying device, such as the Philips™ Airfryer™, may be equipped with NFC functionality for being controlled from an external device. In such an example, the Airfryer™ may operate in a low power standby phase where only the NFC communication functionality is powered. In this mode, the Airfryer™ may provide a user feedback indication when a NFC device is brought into the vicinity. When the NFC device is sufficiently close it can provide instructions on how to perform the frying sequence/program and these instructions are received and stored by the Airfryer™ (e.g. in powered or nonvolatile memory). When the Airfryer™ is powered on, it reads the stored instructions and proceeds to perform a frying operation in accordance with these instructions.

It will be appreciated that the above description for clarity has described embodiments of the invention with reference to different functional circuits, units and processors. However, it will be apparent that any suitable distribution of functionality between different functional circuits, units or processors may be used without detracting from the invention. For example, functionality illustrated to be performed by separate processors or controllers may be performed by the same processor or controllers. Hence, references to specific functional units or circuits are only to be seen as references to suitable means for providing the described functionality rather than indicative of a strict logical or physical structure or organization.

The invention can be implemented in any suitable form including hardware, software, firmware or any combination of these. The invention may optionally be

implemented at least partly as computer software running on one or more data processors and/or digital signal processors. The elements and components of an embodiment of the invention may be physically, functionally and logically implemented in any suitable way. Indeed the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. As such, the invention may be implemented in a single unit or may be physically and functionally distributed between different units, circuits and processors.

Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the present invention is limited only by the accompanying claims. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term comprising does not exclude the presence of other elements or steps.

Furthermore, although individually listed, a plurality of means, elements, circuits or method steps may be implemented by e.g. a single circuit, unit or processor.

Additionally, although individual features may be included in different claims, these may possibly be advantageously combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. Also the inclusion of a feature in one category of claims does not imply a limitation to this category but rather indicates that the feature is equally applicable to other claim categories as appropriate.

Furthermore, the order of features in the claims do not imply any specific order in which the features must be worked and in particular the order of individual steps in a method claim does not imply that the steps must be performed in this order. Rather, the steps may be performed in any suitable order. In addition, singular references do not exclude a plurality. Thus references to "a", "an", "first", "second" etc. do not preclude a plurality. Reference signs in the claims are provided merely as a clarifying example shall not be construed as limiting the scope of the claims in any way.