BACKGROUND

[0002] Haptic feedback may be provided for a user input, for example by vibrating a surface used for providing the user input. Haptic user feedback may be provided in various type of devices, for example transducers. Transducers may convert energy from one form to another and may be applied in various type of devices such as loudspeakers to produce sounds based on electric signals. In general, a loudspeaker may comprise a surface that is caused to vibrate according to the electric signal to produce the sound. In surface audio devices, a surface such as for example a display of a mobile phone, a screen of a television, a panel inside a vehicle, may be configured as a surface for generating a sound. Sounds may be used to provide audio feedback to a user. Furthermore, vibrations may be used to provide haptic or tactile feedback to the user.

SUMMARY

[0003] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. The scope of protection sought for various embodiments of the present disclosure is set out by the independent claims.

[0004] Example embodiments of the present disclosure enable efficient implementation of haptic or audio feedback in a user input device. These and other benefits may be achieved by the features of the independent claims. Further advantageous implementation forms are provided in the dependent claims, the description, and the drawings.

[0005] According to a first aspect, an apparatus is disclosed. The apparatus may comprise: a coil; a magnetic element, wherein displacement of a surface of the apparatus is configured to cause relative movement between the magnetic element and the coil to induce a voltage or current at the coil; detection circuitry coupled to the coil, wherein the detection circuitry is configured to detect a user input on the surface based on a triggering signal comprising the voltage or current induced at the coil by displacement of the surface by a user; and feedback circuitry coupled to the coil, wherein the feedback circuitry is configured to activate a feedback signal, in response to detection of the user input by the detection circuitry, and wherein the coil is configured to cause or alter movement of the surface based on a magnetic field configured to be generated by the coil upon activation of the feedback signal. [0006] According to an alternative example embodiment of the first aspect, the apparatus may comprise: a first coil; a magnetic element, wherein displacement of a surface of the apparatus is configured to cause relative movement between the magnetic element and the first coil to induce a voltage or current at the first coil; detection circuitry coupled to the first coil, wherein the detection circuitry is configured to detect a user input on the surface based on a triggering signal comprising the voltage or current induced at the first coil by displacement of the surface by a user; and feedback circuitry coupled to the first coil or a second coil, wherein the feedback circuitry is configured to activate a feedback signal, in response to detection of the user input by the detection circuitry, and wherein the first coil or the second coil is configured to cause or alter movement of the surface based on a magnetic field configured to be generated by the first coil or the second coil upon activation of the feedback signal, wherein the surface comprises at least one touch sensor, and wherein the feedback circuitry is configured to activate the feedback signal in response to the detection of the user input by the detection circuitry and detecting the user to touch the surface by the at least one touch sensor. [0007] According to an example embodiment of the first aspect, the surface comprises at least one touch sensor, and wherein the feedback circuitry is configured to activate the feedback signal in response to the detection of the user input by the detection circuitry and detecting the user to touch the surface by the at least one touch sensor.

[0008] According to an example embodiment of the first aspect, the apparatus is configured to enable the detection circuitry, in response to detecting the user to come into contact with the surface by the at least one touch sensor.

[0009] According to an example embodiment of the first aspect, the apparatus comprises: a low-pass filter configured to filter the triggering signal, wherein the low-pass filter is configured suppress audio frequencies.

[0010] According to an example embodiment of the first aspect, the feedback signal comprises an audio signal.

[001 1 ] According to an example embodiment of the first aspect, the apparatus comprises: audio circuitry coupled to the coil (or the second coil), wherein the audio circuitry is configured to provide an audio signal to the coil (or the second coil), and wherein the coil (or the second coil) is configured to cause movement of the surface based on a variable magnetic field configured to be generated by the coil (or the second coil) based on the audio signal. The movement of the surface may be caused by movement of the magnetic element. Movement of the magnetic element may be caused by the magnetic field configured to be generated by the coil (or the second coil). The magnetic element may be mechanically coupled to the surface such that movement of the magnetic element causes movement of the surface.

[001 2] According to an example embodiment of the first aspect, the apparatus comprises: a low-pass filter configured to filter the triggering signal, wherein a cutoff frequency of the low-pass filter is between 5-8 Hz.

[001 3] According to an example embodiment of the first aspect, the feedback signal comprises a haptic signal.

[0014] According to an example embodiment of the first aspect, the apparatus is configured to disable the detection circuitry, in response to determining to activate the feedback signal. [001 5] According to an example embodiment of the first aspect, the apparatus is configured to disable the detection circuitry during provision of the feedback signal by the feedback circuitry.

[0016] According to an example embodiment of the first aspect, the apparatus is further configured to derivate the triggering signal to obtain a derivative of the triggering signal; and wherein the feedback circuitry is further configured to: select the feedback signal from a plurality of feedback signals based on a level of a maximum peak of the derivative of the triggering signal and/or a location of the user input detected by the at least one touch sensor; and/or activate the feedback signal, in response to detection of a minimum peak of the derivative of the triggering signal.

[001 7] According to an example embodiment of the first aspect, the apparatus comprises: a top portion comprising the magnetic element and a base portion comprising the coil (or the first coil and/or the second coil), wherein the displacement of the surface by the user is configured to cause the top portion to move towards the base portion.

[0018] According to an example embodiment of the first aspect, base portion further comprises a second magnetic element.

[0019] According to an example embodiment of the first aspect, at least part of the coil (or the first coil and/or the second coil) is configured to encircle the second magnetic element.

[0020] According to an example embodiment of the first aspect, the coil (or the first coil and/or the second coil) comprises a planar coil arranged on a plane substantially parallel to the surface.

[0021 ] According to an example embodiment of the first aspect, the magnetic element and/or the second magnetic element comprises a permanent magnet.

[0022] According to a second aspect, a method is disclosed. The method may comprise: detecting a user input on a surface based on a triggering signal comprising a voltage or current induced at a coil by displacement of the surface by a user, wherein the displacement of the surface is configured to cause relative movement between a magnetic element and the coil to induce a voltage or current at the coil; activating a feedback signal in response to detection of the user input; generating a magnetic field by the coil to cause or alter movement of the surface in response to activation of the feedback signal.

[0023] According to an alternative example embodiment of the second aspect, the method may comprise: detecting a user input on a surface based on a triggering signal comprising a voltage or current induced at a first coil by displacement of the surface by a user, wherein the displacement of the surface is configured to cause relative movement between a magnetic element and the first coil to induce a voltage or current at the first coil; activating a feedback signal in response to detection of the user input; generating a magnetic field by a second coil to cause or alter movement of the surface in response to activation of the feedback signal.

[0024] According to an example embodiment of the second aspect, the surface comprises at least one touch sensor, and the method further comprises: activating the feedback signal in response to the detection of the user input and detecting the user to touch the surface by the at least one touch sensor.

[0025] According to an example embodiment of the second aspect, the method further comprises: enabling detection of the user input, in response to detecting the user to come into contact with the surface by the at least one touch sensor.

[0026] According to an example embodiment of the second aspect, the method further comprises: low-pass filtering the triggering signal to suppress audio frequencies.

[0027] According to an example embodiment of the second aspect, the feedback signal comprises an audio signal.

[0028] According to an example embodiment of the second aspect, the method further comprises: providing an audio signal to the coil (or the second coil); and causing, by the coil (or the second coil), movement of the surface based on a variable magnetic field generated by the coil (or the second coil) based on the audio signal.

[0029] According to an example embodiment of the second aspect, the method further comprises: filtering the triggering signal with a low-pass filter having a cutoff frequency between 5-8 Hz. [0030] According to an example embodiment of the second aspect, the feedback signal comprises a haptic signal.

[0031 ] According to an example embodiment of the second aspect, the method further comprises: disabling detection of the user input, in response to determining to activate the feedback signal.

[0032] According to an example embodiment of the second aspect, the method further comprises: disabling detection of the user input during provision of the feedback signal.

[0033] According to an example embodiment of the second aspect, the method further comprises: derivating the triggering signal to obtain a derivative of the triggering signal; and selecting the feedback signal from a plurality of feedback signals based on a level of a maximum peak of the derivative of the triggering signal and/or a location of the user input detected by the at least one touch sensor, and/or activating the feedback signal, in response to detection of a minimum peak of the derivative of the triggering signal.

[0034] According to an example embodiment of the second aspect, the method is performed by an apparatus comprising: a top portion comprising the magnetic element and a base portion comprising the coil (or the first coil and/or the second coil), wherein the displacement of the surface by the user is configured to cause the top portion to move towards the base portion.

[0035] According to an example embodiment of the second aspect, base portion further comprises a second magnetic element.

[0036] According to an example embodiment of the second aspect, at least part of the coil (or the first coil and/or the second coil) is configured to encircle the second magnetic element.

[0037] According to an example embodiment of the second aspect, the coil (or the first coil and/or the second coil) comprises a planar coil arranged on a plane substantially parallel to the surface.

[0038] According to an example embodiment of the second aspect, the magnetic element and/or the second magnetic element comprises a permanent magnet. [0039] According to a third aspect, a computer program or a computer program product may comprise instructions for causing an apparatus to perform any example embodiment of the method of the second aspect.

[0040] According to a fourth aspect, an apparatus may comprise means for performing any example embodiment of the method of the second aspect.

[0041 ] Any example embodiment may be combined with one or more other example embodiments. Many of the attendant features will be more readily appreciated as they become better understood by reference to the following detailed description considered in connection with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

[0042] The accompanying drawings, which are included to provide a further understanding of the example embodiments and constitute a part of this specification, illustrate example embodiments and together with the description help to understand the example embodiments. In the drawings:

[0043] FIG. 1 illustrates a cross-sectional view of an example of a user input device configured for providing audio or haptic feedback;

[0044] FIG. 2 illustrates an example of a block diagram of a user input device;

[0045] FIG. 3 illustrates an example of a surface audio device with haptic or audio feedback for user input;

[0046] FIG. 4 illustrates an example of a user input device with separate coils for user input detection and feedback;

[0047] FIG. 5 illustrates an example of a user input device with a detection/ feedback coil arranged to encircle a magnetic element;

[0048] FIG. 6 illustrates an example of a raw triggering signal for a press-and- release operation;

[0049] FIG. 7 illustrates an example of a low-pass filtered triggering signal for a press-and-release operation;

[0050] FIG. 8 illustrates an example of velocity and acceleration curves for a press-and-release operation; [0051 ] FIG. 9 illustrates an example of a flow chart for detecting user input and providing feedback;

[0052] FIG. 10 illustrates an example of an apparatus configured to practice one or more example embodiments; and

[0053] FIG. 11 illustrates an example of a method for providing feedback for a user input.

[0054] Like references are used to designate like parts in the accompanying drawings.

DETAILED DESCRIPTION

[0055] Reference will now be made in detail to example embodiments, examples of which are illustrated in the accompanying drawings. The detailed description provided below in connection with the appended drawings is intended as a description of the present examples and is not intended to represent the only forms in which the present example may be constructed or utilized. The description sets forth the functions of the example and the sequence of steps for constructing and operating the example. However, the same or equivalent functions and sequences may be accomplished by different examples.

[0056] FIG. 1 illustrates a cross-sectional view of an example of a user input device. User input device 100 may be configured to generate vibration, such as for example audio output (e.g. audio signals and/or audio feedback) or haptic output (e.g. haptic feedback) to a user, for example in response to detecting a user input (e.g. pressing) of user input device 100.

[0057] User input device 100 may comprise or be configured to be coupled to a surface 102. Surface 102 may be configured to be mechanically displaced, for example along axis 130. Axis 130 may be substantially perpendicular to surface 102. Surface 102 may be a touch sensitive surface, for example by means of one or more touch sensors 102 A integrated within or coupled to surface 102. A touch sensitive surface may be implemented for example based on capacitive sensing. It is however possible to implement user input device 100 without a touch sensitive surface. [0058] User input device 100 may comprise a surface acoustic device, or, a however possible that surface audio haptic device (SAHD) configured to generate an acoustic signal by vibrating surface 102 in the range of audio frequencies (e.g. 20 Hz to 20 kHz). It is the user input device is configured not to provide any audio output.

[0059] User input device 100 may further comprise a (first) magnetic element 110, which may be or be configured to be mechanically (e.g. fixedly) coupled to surface 102. Surface 102 and magnetic element 110 may be located at a top portion of the user input device 100, as will be further described with reference to FIG. 5. Magnetic element 110 may be configured to move along with displacement of surface 102.

[0060] User input device 100 may comprise at least one supporting member 108 [0061 ] for supporting surface 102, for example with respect to a base 104. The user input device 100 may further comprise a (second) magnetic element 120, which may be mechanically (e.g. fixedly) coupled to base 104. Magnetic element 120 may be arranged to face magnetic element 110, as shown in FIG. 1. User input device 100 may comprise a coil 122, for example arranged between magnetic elements 110, 120. Coil 122 may be attached to magnetic element 120. Coil 122 may be located above magnetic element 120 along axis 130 (closer to surface 102 than magnetic element 120). Coil 122 may operate both as a sensing coil (also referred to as a detection coil) and a feedback coil (also referred to as a haptic coil, an audio coil, a sound coil, or a voice coil). Magnetic element 110 and/or magnetic element 120 may comprise a permanent magnet, or magnetizable material, for example ferromagnetic and/or ferrimagnetic material such as iron. The magnetic elements may take different forms in different embodiments and at least one of magnetic elements 110, 120 may comprise a permanent magnet. Magnetic element 110 and/or magnetic element 120 may be also implemented as a combination of several magnetic components.

[0062] When magnetic element 110 comprises a permanent magnet, magnetic element 110 may cause a static magnetic field within the user input device 100. Magnetic element 120 may comprise magnetizable material, which may be magnetized by the magnetic field provided by magnetic element 110. It is however also possible that magnetic element 120 is not present, or, that magnetic element 120 comprises a permanent magnet.

[0063] If magnetic element 120 comprises a permanent magnet, magnetic element 110 may comprise magnetizable material. Magnetic element 120 may cause a static magnetic field within the user input device 100, thereby increasing the level of magnetic induction. An attractive force may be generated between magnetic element 110 and magnetic element 120. Magnetic element 110 may alternatively comprise another permanent magnet. Coil 122 may be located at a base portion of user input device 100. The base portion may comprise also base 104 and/or magnetic element 120. The top portion may be configured to move towards the base portion upon displacement of surface 102 by the user. The top portion may be rigid. Upon displacement of surface 102 the entire top portion may move towards the base portion.

[0064] The magnetic field provided by at least one of magnetic elements 110, 120 may cause an electromagnetic force (EMF) to surface 102 when providing an electric current to coil 122, or cause a voltage to be induced at the 122, when pressing surface 102. The system may be characterized by equation EMF (F) = Blv, where B is the magnetic flux density of the magnetic field, I is the length of the coil wire of coil 122, and v is the speed of the movement of surface 102 along axis 130, caused by a user pressing surface 102. Creating a strong static magnetic field (e.g. by magnetic element 120) therefore increases the level of induced voltage. This improves sensitivity of user input detection. The EMF may be expressed in Volts (V). Surface 102 and/or the at least one supporting member 108 may comprise at least one elastic element providing a force (e.g. a return force), which may act as a counterforce to the electromagnetic force or the pressing force. Surface 102 may be thus supported with respect to the base 104, which may comprise the supporting member(s) 108. This enables movement of the surface with respect to axis 130 with velocity (v), which causes a voltage to be induced at coil 122. Surface 102 may be therefore caused to be in a force equilibrium state. Surface 102 may comprise a panel to be vibrated. Surface 102 may be rigid, for example not bending or bending just a little. Surface 102 may comprise a plane. Surface 102 may comprise, for example, metal, wood, glass, and/or plastics. The thickness of the surface 102 may be at least 1mm, 2mm, 3mm, 5mm, 1 cm, 2 cm, or 5 cm. Base 104 may comprise a panel that is mechanically grounded.

[0065] The electrical signal in coil 122 may be proportional to mechanic displacement of surface 102. The force equilibrium state may be broken by providing an electrical signal to coil 122. For example, when an electrical input signal is fed via the audio/feedback signal terminals to coil 122, the force equilibrium may be broken. Hence, the surface 102 may be caused to vibrate according to the electromotive force (EMF) generated by the electrical input signal in coil 122. Alternatively, the force equilibrium may be broken by mechanic displacement of surface 102 from the position of the force equilibrium state, for example by pressing surface 102 by the user.

[0066] It is noted that the polarities of the magnetic elements 110, 120 may be arranged in any suitable manner. For example, in an attractive configuration, opposite magnetic poles may be arranged towards each other ( N-S to N-S or S-N to S-N). The force equilibrium may be therefore caused by the attractive magnetic force between the magnetic elements 110, 120 and an opposite support force provided by the supporting member(s) 118 that prevent the magnetic elements 110, 120 from being drawn to each other. Alternatively, in a repulsive configuration, same magnetic poles may be arranged towards each other (N-S to S-N or S-N to N-S). The force equilibrium may be therefore caused by the repulsive magnetic force between the magnetic elements 110, 120 and an opposite support force provided by the supporting member(s) 118 that prevents the magnetic elements 110, 120 from being pushed away from each other.

[0067] User input device 100 may be configured to generate an audio output according to the electrical input signal. Audio output may mean and/or comprise sound that is detectable by human ear, i.e. sound that may be heard by a human. Audio output may also refer to sound that is detectable by animal(s) and/or audio sensors (e.g. microphone). For example, the audio output may comprise music, speech, sound effects, or the like. It is also pointed out that surface 102 and base 104 be comprised in any suitable apparatus such as for example a mobile phone, a television, a computer, a music player, or some other type of user device. For example, base 104 may form at least a part of a frame of the apparatus. For example, surface 102 may be or be comprised in a screen of the apparatus (e.g. an electronic apparatus), or wrist device (e.g. surface 102 may be comprised in a display of such device). The provided solution may be for example applicable to the automotive industry (e.g. cars). Surface 102 may comprise a car panel such as an interior panel of a car (e.g. door panel, ceiling or roof panel, wall panel, frame panel, or some other part of the car interior). Surface 102 may for example comprise a display of a car. Surface 102 may be alternatively comprised in a wearable device, such as a wearable electronic device. For example, surface 102 may be comprised in a portable electronic device, such as a watch

[0068] As noted above, the user input device 100 may comprise one or more audio/feedback signal terminals electrically coupled to coil 122. The audio/feedback signal terminal(s) may be used to provide audio and/or feedback signals to coil 122 to cause generation of audio and/or haptic vibration by surface 102. A feedback signal may comprise audio and/or haptic feedback. The user input device 100 may further comprise one or more triggering signal terminals electrically coupled to the coil 122. The triggering signal may be alternatively called a sensing signal or detection signal. The triggering signal terminal(s) enable a triggering signal to be output from coil 122. For example, upon mechanical displacement of surface 102, for example by pressing surface 102 along axis 130, a voltage (triggering voltage) may be induced between the triggering signal terminals. The triggering signal may be used to detect pressing of surface 102 and to trigger audio/haptic feedback to be generated by means of the same coil 122, as will be further described below. Even though the audio/feedback signal terminals and triggering signal terminals have been illustrated to include both positive and negative terminals, it is appreciated that each coil could be alternatively coupled to a single terminal with respect to a ground potential. Also, the triggering signal, the feedback signal, and/or the audio signal may be input/output to/from coil 122 with common terminal(s). [0069] Surface 102 may be supported with respect to base 104 using various solutions. The supporting member(s) 108 may for example comprise spring(s) disposed between surface 102 and base 104. However, the supporting member(s) 108 may not be present in some embodiments, since the counterforce may be also provided by other means, such as for example by pair(s) of magnets coupled with surface 102 and base 104. For example, the pair(s) of magnets could be configured to provide a force that is opposite to the force provided by magnetic elements 110, 120. For example, if the magnetic element 110 and the magnetic element 120 are configured to provide an attractive force, the pair(s) of magnets may be configured to provide a repulsive force, or vice versa.

[0070] Coupling of a magnetic element with surface 102 or base 104 may comprise fixing or attaching the magnetic element to surface 102 or base 104. Such fixing may be performed for example using glue and/or screw(s). Magnetic elements may be also printed on surface 102 and/or base 104. The coupling may therefore comprise printing (e.g. electronics printing). Furthermore, the arrangement of coil 122 between the magnetic elements 110, 120 may comprise coupling (e.g. fixing or attaching) coil 122 with magnetic element 120. However, coil 122 may be also arranged as a separate element between magnetic elements 110, 120. Hence, coil 122 may not physically touch magnetic element 120. For example, coil 122 may be attached to base 104 or some other part of the user input device 100 to place coil 122 at a location between magnetic elements 110, 120.

[0071 ] It is noted that the example of FIG. 1 illustrates one possible arrangement of magnetic element(s) 110, 120 and coil 122 with respect to the surface 102 and the base 104. Similar functionality may be also achieved with alternative arrangements. For example, coil 122 may be located at the top portion (e.g. mechanically coupled to surface 102), interacting with magnetic element 120 located at the base portion. Note that it is possible that only one of magnetic elements 110, 120 is present. If coil 122 is coupled to base 104, magnetic element 120 may not be present. If coil 122 is coupled to surface 102, magnetic element 110 may not be present. Example embodiments of the present disclosure enable user input detection and haptic and/or audio feedback functionalities to be implemented within a single construction. For example, a single coil may be used for detecting user input and providing haptic/audio feedback to the user. The same coil may be further configured to output an audio signal (e.g. music) by vibrating surface 102. Coil 122 may comprise a planar coil at a plane that is parallel to surface 102. This enables to reduce thickness of user input device 100. At least part of coil 122 may be configured to encircle magnetic element 120.

[0072] FIG. 2 illustrates an example of a block diagram of a user input device. A simplified version of user input device 100 is illustrated in FIG. 2. In addition to user input device 100, user input device 200 may comprise detection circuitry 210 and feedback circuitry 220. Detection circuitry 210 and feedback circuitry 220 may be implemented separately or combined within single circuitry and/or software.

[0073] Detection circuitry 210 may be coupled (electrically) to coil 122, for example to receive triggering signals from coil 122 and to detect user inputs based on the triggering signals. A triggering signal may comprise a voltage or current induced at coil 122 by displacement of surface 102 by the user. In response to detecting a user input, e.g. press of surface 102, detection circuitry 210 may provide an enable feedback signal (EN_FB) to feedback circuitry 220. Providing an enable signal may comprise changing a state of the enable signal, for example from a level indicative of logical low to a level indicative of logical high. Enable signal may however comprise any suitable indication of a request to enable the feedback signal. [0074] Feedback circuitry 220 may be coupled (electrically) to coil 122, for example to provide feedback signal(s) to coil 122. The feedback circuitry 220 may be configured to activate (and deactivate) the feedback signal, for example according to the enable feedback signal provided by detection circuitry 210, that is, in response to detection of the user input by detection circuitry 210. Coil 122 may be configured to cause movement of surface 102 based on a magnetic field configured to be generated by coil 122 upon activation of the feedback signal. For example, if a direct current (DC) signal is provided as a feedback signal, the magnetic field may cause surface 102 to be lifted, thereby resulting in a single bump as haptic feedback. Alternatively, the feedback signal may comprise an alternating current (AC) signal, which may cause surface 102 to vibrate. Vibrations of the surface 102 may be sensed by the user as haptic feedback and/or audio feedback.

[0075] User input device 200 may comprise filter for filtering the triggering signal, represented in this example by low-pass filter (LPF) 202. LPF 202 may be implemented using any suitable circuitry. LPF 202 may comprise an analog RC (resistor-capacitor) circuit, or, if the detection circuitry 210 is (at least partially) implemented using digital logic, the low-pass filter 212 may comprise for example a finite impulse response (FIR) filter or an infinite impulse response (IIR) filter configured to process digital samples obtained by analog-to-digital (A/D) conversion of the triggering signal.

[0076] When the feedback signal comprises an audio signal (e.g. a beep), and/or when coil 122 and surface 102 are used to generate audio output (e.g. music) separate from the feedback signal, LPF 202 may be configured to suppress audio frequencies (e.g. 20 Hz - 20 kHz). LPF 202 may be configured to pass haptic frequencies (e.g. 0-10 Hz). A cut-off frequency of LPF 202 may be between 8-20 Hz or 10-20 Hz, for example between 8-12 Hz (e.g. approximately at 10 Hz). LPF 202 enables to filter out the feedback (audio) signal and/or a separate audio output signal from the triggering signal. Cut-off frequency close to 10 Hz enables to detect fast press-release actions occurring in the order of 0.1 s, while providing sufficient guard distance to the audio signals (> 20 Hz). In digital implementations the guard distance enables to use a low-complexity filter, which reduces the processing time and hence enables timely feedback to be provided to the user.

[0077] When the feedback signal comprises a haptic signal, LPF 202 may be configured to suppress also haptic frequencies. The cut-off frequency of LPF 202 may be for example between 5-8 Hz. This enables user input detection while suppressing interference caused by the haptic feedback signal. Frequency of the haptic feedback signal may be for example 8-10 Hz.

[0078] Use input device 200 may further comprise an amplifier 204 for amplifying the triggering signal. Amplifier 204 may be for example located between LPF 202 and detection circuitry 210. LPF 202 and/or amplifier 204 may be implemented within detection circuitry 210 or the system may be implemented without LPF 202 and/or amplifier 204.

[0079] Enabling user input detection by detection circuitry 210 may be conditioned on detecting the user to touch surface 102, for example by touch sensor(s) 102A. This approach may be applied for example to implement a comparator or ADC based user input detector with capacitive touch support. In this case, simultaneous activation of the triggering signal and touch sensor output may be used to trigger haptic/audio feedback. This may be beneficial, for example because user input detection during haptic feedback may be somewhat unreliable. Hence, detection circuitry 210 may be configured to ignore any triggering signal during the haptic feedback. Detecting the user to touch surface 102 may be used as a trigger for activating user input detection again. After provision of the feedback signal the system may go to an initial state, where detection circuitry 210 is disabled and waiting for activation by the touch sensor output. Touch sensor(s) 102A may also detect location of the touch and/or the user input, thereby enabling for example location-based selection of feedback signals.

[0080] In the example of FIG. 2, output of the touch sensor(s) 102A may be provided to detection circuitry 210. The output of the touch sensor(s) may be used to enable or disable user input detection by detection circuitry 210. User input device 200 may to disable user input detection (e.g. disable detection circuitry 210), in response to determining to activate the feedback signal. For example, detection circuitry 210 may stop monitoring the triggering signal, in response to providing the feedback enable signal to feedback circuitry 220. User input detection may be kept disabled during provision of the feedback signal by feedback circuitry 220, for example for a predetermined time, or until receiving, from feedback circuitry 220, an indication that provision of the feedback signal has terminated.

[0081 ] FIG. 3 illustrates an example of a surface audio device with haptic or audio feedback for user input. Surface audio device 300 may include components similar to user input device 200, for example coil 122, detection circuitry 210, and feedback circuitry 220. Feedback circuitry 220 may comprise an audio amplifier (AMP) to output an audio signal simultaneously with detection of the user input by detection circuitry 210. Alternatively, such audio amplifier may be implemented separate from feedback circuitry 220. The audio signal may be separate from the feedback signal (audio/haptic).

[0082] Surface audio device 300 may comprise LPF 202, referred to as first LPF in this example, and/or amplifier 204. Surface audio device 300 may comprise an analog-to-digital converter (ADC) 206. As noted above, the cut-off frequency of LPF 202 may be for example 10 Hz to filter higher frequency interference away from the triggering signal. Interference may be for example due to mechanical vibration, electric distortion, or the audio signal. LPF 202 may also prevent aliasing when sampling the triggering signal with ADC 206. Surface audio device 200 may comprise another LPF 208, which may be configured to filter the triggering signal after amplification by amplifier 204. LPF 208 may comprise a digital filter configured to process the triggering signal digitized by ADC 206. Cut-off frequency of LPF 208 may be similar to LPF 202, e.g. selected from the example values provided for LPF 202. Noise sources in the system may include the audio amplifier (e.g. within feedback circuitry 220), LPF 202, amplifier 204, and ADC 206. Also the sensing band may be noisy. A target level for noise may be under 0.3 mV(rms) to have good signal-to-noise ratio (SNR) for the triggering signal. Gain G of amplifier may be therefore between 1 - 5.

[0083] Feedback circuitry 220 may comprise circuitry 222 for activating feedback. The feedback signal may be retrieved from a signal bank, for example a haptic signal bank and/or an audio signal bank. The signal bank may be for example included in a memory of surface audio device 300. Feedback circuitry 220 may access the memory to retrieve the feedback signal from the signal bank upon enablement of the feedback signal. Alternatively, or additionally, the feedback signal may comprise a DC (direct current) voltage or a DC current. If the DC current or voltage is provided in addition to an audio feedback signal and/or audio played from an audio source, the DC current or voltage may form a component of the electric signal provided to coil 122. Applying the DC current or voltage as haptic feedback enables to generate haptic feedback (e.g. a single bump of the surface 102), which may be easily recognized by the user from other vibrations of the surface 102 caused for example by audio playback.

[0084] Coil 122 may be therefore coupled to an audio source (audio circuitry), for example the audio amplifier integrated within feedback circuitry 220. The audio source may be configured to play audio signals (e.g. music or sounds) by causing vibration of the surface 102 by means of coil 122. If audio playback is ongoing, and therefore the surface 102 vibrating, the feedback signal (haptic/audio) may alter movement of surface 102 by altering the magnetic field provided by the coil 122. For example, a haptic feedback signal or an audio feedback signal may be superimposed to the audio signal played by the audio source.

[0085] User input device 300 may further comprise a high-pass filter (HPF) (not shown) for filtering the feedback signal. The high-pass filter may be used for example to reduce the amount of interference caused to the triggering signal when the feedback signal comprises an audio signal.

[0086] Detection circuitry 210 and feedback circuitry 220 may be implemented using analog or digital circuits, or a combination thereof. In the analog domain these circuitries may be implemented for example based on comparator, derivator, or integrator circuits, or the like. In the digital domain, the circuitries may comprise digital components such as for example logic gates, other digital logic, or processor circuitry such as a microcontroller unit (MCU) associated with at least one memory. An example of a discrete comparator circuit is the Schmitt trigger, which includes hysteresis with respect to its input. Noise and other interferences may therefore not change the status of its output. Alternatively, internal comparator of an MCU may be used.

[0087] Detection circuitry 210 may perform detection (sensing) with a frequency of 0.5-3 Hz, that is, with detection intervals of 0.33-2 s. Voltage level of the triggering signal (before amplification) may be in the range of 1-50 mV(rms). Assuming the pressing force is the same, voltage level of the triggering signal is halved when frequency is halved. In frequency-magnitude domain there may by thus a gain of 6 dB/octave. Voltage level of the audio signal may be in the range of 0-8 V(rms). Frequency of the audio signal may be in the range of 20 Hz - 20 kHz. [0088] Even though illustrated without the touch sensor 102 A, apparatus 300 may comprise similar touch sensor functionality as apparatus 100 or 200. In general, functionalities and/or structural blocks of the devices described herein may be combined and/or to generate further examples.

[0089] FIG. 4 illustrates an example of a user input device with separate coils for user input detection and feedback. Example embodiments described herein may be also applied to user input devices having separate detection and feedback coils. User input device 400 may comprise user input device 100, however in this example [0090] with separate detection coil 412 and feedback coil 422 instead of coil 122. Detection coil 412 may be coupled to detection circuitry 210 and feedback coil 422 may be coupled to feedback circuitry 220. User input device 400 may comprise touch sensor(s) 102 A coupled to detection circuitry 210. Coils 412 and 422 may be located for example at the base portion of user input device 100. Touch sensor(s) 102A may be used as described above with reference to single-coil devices 100, 200, 300.

[0091 ] User input device 400 may therefore comprise: a first coil (detection coil 412); a magnetic element (e.g. magnetic element 110). Displacement of surface 102 of user input device 400 may be configured to cause relative movement between the magnetic element and the first coil to induce a voltage or current at the first coil. User input device 400 may further comprise detection circuitry 210 coupled to the first coil and configured to detect a user input on surface 102 based on a triggering signal comprising the voltage or current induced at the first coil by displacement of surface 102 by a user. User input device 400 may further comprise feedback circuitry 220 coupled to a second coil (e.g. feedback coil 422) and configured to activate a feedback signal, in response to detection of the user input by detection circuitry 210. The second coil may be configured to cause or alter movement of surface 102 based on a magnetic field generated by the second coil upon activation of the feedback signal. Surface 102 of user input device 400 may comprise touch sensor(s) 102 A. Feedback circuitry 220 may activate the feedback signal, in response to the detection of the user input by detection circuitry 210 and (e.g. simultaneously) detecting, by the touch sensor(s) 102A, the user to touch surface 102. When the second coil is not present (e.g. in case of single-coil devices 200, 300), the feedback signal may be provided to the detection coil (“first coil” in this example).

[0092] FIG. 5 illustrates an example of a user input device with a detection/ feedback coil arranged to encircle a magnetic element. User input device 500 may comprise a top portion 310 and a base portion 320. User input device 500 may further comprise at least one (third) magnetic element 312 and/or at least one (fourth) magnetic element 322 comprising magnetic material. Magnetic element(s) 312, 322 may comprise or be made of magnetizable material that acquire their magnetic properties under an external magnetic field. Magnetic element(s) 312, 322 may for example comprise ferromagnetic and/or ferrimagnetic material(s), such as for example iron. Magnetic element 312 may comprise a cavity for magnetic element 110. Magnetic element 312 may for example enclose magnetic element 110 from the top of magnetic element 110 and at least partially from the sides of magnetic element 110.

[0093] Magnetic element 322 may comprise a cavity for magnetic element 120 and coil 122. Magnetic element 322 may enclose magnetic element 120 from the bottom of magnetic element 120 and at least partially from the sides of magnetic element 120. Magnetic element 322 may also enclose coil 122 from the sides of coil 122. The cup-shape of magnetic element 322 enables to guide the magnetic flux to coil 122, thereby strengthening magnetic induction and improving detection sensitivity.

[0094] Top portion 310 may comprise at least magnetic element 110. Top portion 310 may further comprise magnetic element 312. Top portion 310 may be or be configured to be coupled to surface 102 (not shown). Alternatively, top portion 310 may comprise surface 102. A base portion 320 may comprise at least coil 122, or two coils (cf. coils 412, 422), for example encircling magnetic element 120. In case of two coils, coil 412 (detection) may be located above coil 422 (feedback). Base portion 320 may further comprise magnetic element 120 and/or magnetic element 322. Displacement of surface 102 by the pressing force provided by the user may be configured to cause movement of top portion 310 towards base portion 320 (entire top portion 310 may move towards base portion 320). Displacement of surface 102 may be configured to cause relative movement between magnetic element 110 and coil 122 to induce the triggering signal at coil 122. However, in general the displacement of the surface 102 may be configured to cause relative movement between at least one magnet and a coil (122, 412) to induce the triggering signal. Various different arrangements may be therefore used to cause generation of the triggering signal by the user.

[0095] Inner diameter of coil 122 may be substantially equal to or higher than outer diameter(s) of the magnetic elements 110 and/or 120. Hence, majority of the magnetic flux may flow through coil 122, thereby increasing the level of induced voltage/current. Coil(s) may be arranged around magnetic element 120, which may be circular and lie at a plane (parallel to surface 102) defined by the bottom of magnetic element 322, or in general base 104. Base portion 320 is further illustrated on the right by a top view.

[0096] Furthermore, at least part of coil 122 may be configured to encircle magnetic element 120. When a coil is configured to partially encircle magnetic element 120, at least one wire of the coil may encircle magnetic element 120. In dual-coil embodiments (e.g. FIG. 4), one or both of the coils (412, 422) may be configured to at least partially encircle magnetic element 120.

[0097] Magnetic element 120 may take various forms. In the example of FIG. 5, magnetic element 120 is enclosed by magnetic element 322 from the bottom and fully from the sides. It is however possible that the magnetic element 120 is only partially enclosed by the magnetic element 322 from the sides of magnetic element 120. Coil 122 (or coils 412 and 422) may be however located between the magnetic element 120 and magnetic element 322. Magnetic element 120 may be circular (hollow cylinder), as in FIG. 5, or it may be cylindrical. Magnetic element 120 may however take any suitable shape, for example a rectangular cylinder or a hollow rectangular cylinder. Shape of coil 122 (or 412, 422) may be also non-circular, for example rectangular. Any of the coils may be a planar coil, for example wound or printed such that coil wires of the coil do not overlap in the direction of axis 130. Alternatively, any of the coils may be wound such that coil wires of a single coil overlap also (or only) in direction of axis 130. According to an example embodiment, the resistance of the coil 122 may be between 22-26 ohms, for example approximately 24 ohms. The length of the wire of coil 122 may be 3.8-4.2 m, for example approximately 4 m. Coil 122 may have 90-110 turns, for example 100 turns. Such choices for the coil parameters enable to improve sensitivity of user input detection when coil 122 is at least partially enclosed by magnetic element 322. [0098] FIG. 6 illustrates an example of a raw triggering signal for a press-and- release operation. The voltage (mV) of the raw triggering signal is illustrated with respect to time (s) as it is coming from coil 122 or 412. It is observed that the raw triggering signal may have high frequency components, for example due to audio interference, superimposed on the voltage induced at coil 122 or 412 by the user input.

[0099] FIG. 7 illustrates an example of a low-pass filtered triggering signal a press-and-release operation. A peak (“1”) of the voltage induced at coil 122 occurs when the movement of surface 102 (coupled with magnetic element 110) towards the base 104 is fastest, that is, during pressing surface 102. Upon release (“2”) of surface 102 the voltage crosses the zero level and a negative voltage is induced to coil 122 when surface 102 moves away from base 104. In other words, point “1” may correspond to the maximum speed of the movement and point “2” may correspond to change of the direction of the movement (zero-crossing). It is noted that the polarity of the voltage may be alternatively arranged to be different, or the voltage may be referenced to ground level.

[00100] FIG. 8 illustrates an example of velocity and acceleration curves for a press-and-release operation. Start and end times of a press-release action are illustrated with the vertical lines. The velocity curve may correspond to the triggering signal. The acceleration curve may be obtained by derivating the velocity. Acceleration may be advantageously used to determine characteristics of the user input, for example to distinguish between quick and slow presses. Different feedback signals (e.g. haptic feedback with different frequencies) may be selected for different typed of user inputs. [00101 ] Threshold(s) may be set such that peak detection (either maximum or minimum) is conditioned on the threshold(s). For example, a first threshold (th _max ) may be set for detecting a positive peak of acceleration. A second threshold (th _min ) may be set for detecting a negative peak of acceleration. Absolute value of the first threshold may be higher than the absolute value of the second threshold. This improves peak detection reliability. The threshold(s) may be however tunable to enable the device to be adapted to different operating environment. Peaks of the acceleration signal may be determined by derivating the acceleration signal and identifying zeros of the derivated acceleration signal. A peak level may be determined as the signal level at a zero-point of the derivative. Based on the level of the maximum peak (positive), user input device 200, 300, 400 may select a feedback signal. The feedback signal may be selected from a set of feedback signals, where each feedback signal may correspond to a range of maximum peak levels. As noted above, this improves user experience, because different feedback may be provided for different type of user inputs (e.g. fast vs. slow).

[00102] User input device 200, 300, 400 may activate the feedback signal when detecting the minimum peak (negative) of the acceleration. User feedback may be therefore provided starting from the minimum peak. This enables to time the feedback at the point of maximum pressure during the press, resulting in comfortable user experience.

[00103] Analysing the acceleration (derivative of the triggering signal) may be performed at feedback circuitry 220. In this case, the triggering signal (or its derivative) may be provided to feedback circuitry 220. Feedback circuitry 220 may select the feedback signal and provide the feedback signal at the correct time (e.g. triggered by the minimum peak of acceleration).

[00104] Alternatively, detection circuitry 210 may analyse the acceleration, and provide an indication of the selected feedback signal to feedback circuitry 220. Detection circuitry 220 may provide the feedback enable signal to feedback circuitry 220 at the correct time. [00105] FIG. 9 illustrates an example of a flow chart for detecting user input and providing feedback. The procedure of FIG. 9 may be performed by any of devices 200, 300, or 400.

[00106] At operation 901, the device may be in an initial state. At the initial state, detection circuitry 210 may be disabled, e.g. powered off or down. The device may therefore not monitor the triggering signal induced at coil 122 or 412. Touch sensor(s) 102A may be however activated.

[00107] At operation 902, the device may determine whether a touch was detected at surface 102. A touch may be detected when the user to comes into contact with surface 102. This may be detected by touch sensor(s) 102 A. Output of touch sensor(s) 102 A may be active as long as the user touches surface 102. Device may iterate operation 902 until a touch is detected.

[00108] The device may also determine location(s) (touch location) of the touch at surface 102. The touch location(s) may be used for selecting the feedback signal, as will be further described with reference to operation 905.

[00109] At operation 903, the device may activate user input detection by detection circuitry 210. Conditioning the user input detection on the touch detection enables to avoid false user input detections and to reduce power consumption. It is however possible that user input detection is kept active in parallel with touch detection. In this case, detecting both the touch by touch sensor(s) 102A and user input by detection circuitry 210 may trigger provision of the feedback signal. The touch may be associated with a certain location on surface 102. The touch may be alternatively associated with multiple locations on surface 102. For example, a wipe or a sweep gesture on surface 102 may be detected based on touch sensor(s) 102A. For example, volume may be adjusted by a wipe/sweep gesture on surface 102 in particular direction(s).

[001 10] At operation 904, the device may determine whether a user input was detected. Operation 904 may comprise peak detection for the triggering signal. In this example, voltage u is used to represent the triggering signal. Peak detection may comprise derivating the triggering signal, e.g., by a derivator circuit, which may comprise an analog derivator circuit or a digital processing circuit (e.g. based on differences between consecutive samples of the triggering signal). The derivator circuit may provide as output a derivative (e.g. first order derivative) with respect to a time interval (du/dt). The first order derivative of the triggering signal may indicate acceleration of surface 102 upon the user input, for example with respect to base 104.

[001 1 1 ] A peak of the triggering signal may be detected. Depending on polarity of the triggering signal (voltage), the peak may be detected either at positive or negative voltage. To detect a peak, the device may for example determine whether u > 0 and whether the derivative of the triggering signal is (substantially) equal to zero (du/dt = 0). If both conditions are met, a peak has been detected. It is noted that determining whether du/dt is substantially zero may in practise comprise determining whether du/dt decreases below a threshold. In response to detecting a peak, an indication of detected user input may be provided.

[001 1 2] Alternatively, or additionally, the device may use the derivative of the triggering signal (acceleration) for user input detection. As described with reference to FIG. 8, this enables to optimize the time of providing the feedback signal. As illustrated in FIG. 8, the maximum peak of the acceleration comes before the maximum peak of the velocity (cf. triggering signal). Initiating the feedback in response to the maximum peak of acceleration enables to provide the feedback right before the maximum pressing force applied by the user. This may be perceived by the user as a logical time for the feedback. By contrast, if the feedback signal is triggered by the maximum peak of velocity, the feedback may be late and the user may notice the feedback when (s)he is already releasing the surface. The magnitude of the maximum peak of the acceleration may be indicative of the quickness of the press action. Since this peak may be detected prior to the moment of maximum pressing force (e.g. at zero-crossing of the triggering signal from positive to negative side), feedback may be provided at an appropriate time.

[001 1 3] As also described above, the acceleration signal may be used to determine the “speed” (e.g. quickness) of the press (e.g. based on level of maximum peak of acceleration). This parameter (press _speed) may for example indicate whether the press is quick or slow and it may be provided as an input to operation 905.

[001 14] At operation 905, the device may select feedback signal, disable user input detection, and/or activate the feedback signal. Firstly, the feedback signal may be selected based on location of the user input. The location of the user input may be detected by the touch sensor(s). The location may be associated with the time of detecting the user input by detection circuitry 210. Different locations of surface 102 may be configured with different user inputs, such as for example adjusting audio volume up or down, adjusting cruise control of a car (e.g. faster or slower), or selection of display functionality (e.g. navigation, phone call, car status). Functions controlled by different touch locations may be determined based on a current user interface configuration (e.g. application) of the device.

[001 1 5] Secondly, the feedback signal may be selected based on acceleration of the press (derivative of the triggering signal). For example, an amount of change of a parameter to be adjusted may be determined based on the acceleration of the press. The feedback signal may reflect the amount of change. For example, if audio volume is adjusted, a quick press may be configured to change the audio volume more than a slow press. Feedback with higher intensity (e.g. amplitude) or frequency may be provided for a quick press. Feedback with lower intensity or frequency may be provided for a slow press. Similar approach may be used for other user inputs, for example for adjusting cruise control of a car.

[001 1 6] The feedback signal may be also determined based on a combination of the touch location and the acceleration of the user input. These two inputs may be therefore mixed. It is however possible to bypass one of the inputs. For example, location of the user input may be used for determining whether to adjust audio volume up or down. The acceleration may be used to determine how much the audio volume is changed in the direction defined by the touch location. Corresponding feedback signal may be then determined. Before activating the feedback signal, the device may disable user input detection. Similar approach may be applied to other parameters, such as for example adjusting brightness of a display, etc. User input detected by touch sensor(s) 102A may comprise two-finger gestures, e.g. for zooming.

[001 1 7] At operation 906, the device may determine whether the touch has been released, e.g., whether the user has lifted his/her finger from surface 102. This may be again determined based on the output of touch sensor(s) 102A. If the touch has not been released, the device may continue to provide the feedback signal. The device may therefore provide the feedback signal until the touch is released.

[001 1 8] At operation 907, the feedback signal may be deactivated, for example in response to detecting the touch to be released at operation 906. It is however possible to deactivate the feedback signal based on other criteria, such as for example expiry of a predetermined time period after activation of the feedback signal. If the touch is not released (e.g. at the end of the predetermined time period) and this is detected by touch sensor(s) 102A, the device may perform initialization (e.g. enable user input detection) if the triggering signal is substantially equal to zero (i.e. indicative of no vertical movement of surface 102). This enables to detect further user inputs by detection circuitry 210, even if the user would not terminate the touch between user inputs.

[001 1 9] The procedure of FIG. 9 improves user experience by enabling appropriate timing of feedback for a user input. Reliability of user input detection may be improved by the joint use of touch sensors and induction based detection. User experience may be further improved by enabling location and acceleration based feedback signals.

[001 20] FIG. 10 illustrates an example of an apparatus configured to practice one or more example embodiments. Apparatus 1000 may comprise at least one processor 1002. The at least one processor 1002 may comprise, for example, one or more of various processing devices or processor circuitry, such as for example a coprocessor, a microprocessor, a controller, a digital signal processor (DSP), a processing circuitry with or without an accompanying DSP, or various other processing devices including integrated circuits such as, for example, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a microcontroller unit (MCU), a hardware (HW) accelerator, a special-purpose computer chip, or the like.

[001 21 ] Apparatus 1000 may further comprise at least one memory 1004. The at least one memory 1004 may be configured to store, for example, computer program code or the like, for example operating system software and application software. The at least one memory 1004 may comprise one or more volatile memory devices, one or more non-volatile memory devices, and/or a combination thereof. For example, the at least one memory 1004 may be embodied as magnetic storage devices (such as hard disk drives, floppy disks, magnetic tapes, etc.), optical magnetic storage devices, or semiconductor memories (such as mask ROM, PROM (programmable ROM), EPROM (erasable PROM), flash ROM, RAM (random access memory), etc.).

[001 22] Apparatus 1000 may further comprise a communication interface (not shown) configured to enable the apparatus to send and/or receive information, for example configuration information comprising a library or bank of feedback signal(s) or mappings between different user inputs (e.g. positions on a surface of a user input device) with different feedback signals. Alternatively, such information may be preconfigured at apparatus 1000. The communication interface may for example comprise a short-range wireless network connection (e.g. Bluetooth or WiFi), or a cellular communication interface, for example according to the 3 ^rd generation partnership project (3 GPP) specifications. Apparatus 1000 may further comprise a user interface (not shown). The user interface may comprise for example surface 102.

[001 23] When apparatus 1000 is configured to implement some functionality, some component and/or components of apparatus 1000, such as for example the at least one processor 1002 and/or the at least one memory 1004, may be configured to implement this functionality. Furthermore, when the at least one processor 1002 is configured to implement some functionality, this functionality may be implemented using the program code 1006 comprised, for example, in the at least one memory 1004. [001 24] The functionality described herein may be performed, at least in part, by one or more computer program product components such as software components. According to an embodiment, the apparatus comprises a processor or processor circuitry, such as for example a microcontroller, configured by the program code when executed to execute the embodiments of the operations and functionality described. Alternatively, or in addition, the functionality described herein can be performed, at least in part, by one or more hardware logic components. For example, and without limitation, illustrative types of hardware logic components that can be used include Field-programmable Gate Arrays (FPGAs), applicationspecific Integrated Circuits (ASICs), application-specific Standard Products (ASSPs), System-on-a-chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), Graphics Processing Units (GPUs).

[001 25] Apparatus 1000 comprises means for performing at least one example embodiment described herein. In one example, the means comprises the at least one processor 1002, the at least one memory 1004 including program code 1006 configured to, when executed by the at least one processor, cause apparatus 1000 to perform the example embodiment(s). Alternatively, or additionally, the means may comprise one or more of the structural elements of the figures, for example the coil 122, 412, 422, or the like. Although apparatus 1000 is illustrated as a single device it is appreciated that, wherever applicable, functions of apparatus 1000 may be distributed to a plurality of device, for example to implement example embodiments by means of distributed computing.

[001 26] FIG. 11 illustrates an example of a method for providing audio or haptic feedback to a user, according to one or more example embodiments.

[001 27] At 1101, the method may comprise detecting a user input on a surface based on a triggering signal comprising a voltage or current induced at a coil by displacement of the surface by a user, wherein the displacement of the surface is configured to cause relative movement between a magnetic element and the coil to induce a voltage or current at the coil.

[001 28] At 1102, the method may comprise activating a feedback signal in response to detection of the user input. [001 29] At 1103, the method may comprise generating a magnetic field by the coil to cause or alter movement of the surface in response to activation of the feedback signal.

[001 30] Further features of the method directly result for example from the functionalities and parameters of the devices 100, 200, 300, 400, or 500 as described in the appended claims and throughout the specification, and are therefore not repeated here. Different variations of the methods may be also applied, as described in connection with the various example embodiments.

[001 31 ] An apparatus may be configured to perform or cause performance of any aspect of the methods described herein. Further, a computer program or a computer program product may comprise instructions for causing, when executed, an apparatus to perform any aspect of the methods described herein. Further, an apparatus may comprise means for performing any aspect of the method(s) described herein. According to an example embodiment, the means comprises at least one processor, and at least one memory including program code, the at least one processor, and program code configured to, when executed by the at least one processor, cause performance of any aspect of the method(s). The means may comprise the structural elements described herein.

[001 32] Any range or device value given herein may be extended or altered without losing the effect sought. Also, any embodiment may be combined with another embodiment unless explicitly disallowed.

[001 33] Although the subject matter has been described in language specific to structural features and/or acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as examples of implementing the claims and other equivalent features and acts are intended to be within the scope of the claims.

[001 34] It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages. It will further be understood that reference to 'an' item may refer to one or more of those items.

[001 35] The steps or operations of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate. Additionally, individual blocks may be deleted from any of the methods without departing from the scope of the subject matter described herein. Aspects of any of the embodiments described above may be combined with aspects of any of the other embodiments described to form further embodiments without losing the effect sought.

[001 36] The term 'comprising' is used herein to mean including the method, blocks, or elements identified, but that such blocks or elements do not comprise an exclusive list and a method or apparatus may contain additional blocks or elements. [001 37] As used in this application, the term ‘circuitry’ may refer to one or more or of the following: (1) hardware-only circuit implementations (such as for example implementations in only analog and/or digital circuitry) and (2) combinations of hardware circuits and software, for example: (i) a combination of analog and/or digital hardware circuit(s) with software/firmware and (ii) any portions of hardware processor(s) with software (e.g. digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus to perform the various example embodiments and (3) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[001 38] It will be understood that the above description is given by way of example only and that various modifications may be made by those skilled in the art. The above specification, examples and data provide a complete description of the structure and use of exemplary embodiments. Although various embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from scope of this specification.