FI129993B - Transducer arrangement - Google Patents

Abstract

There is provided an arrangement (100) for generating vibration according to an electrical input signal, the arrangement (100) comprising: first and second permanent magnets (110, 120) and a coil (122) arranged therebetween. The first permanent magnet (110) is coupled with a Surface (102) which is configured to vibrate according to an electrical input signal inputted into the coil (122). The arrangement (100) further comprises a first magnetic object (210) configured to be coupled with the surface (102) and to at least partially encircle the first permanent magnet (110); and a second magnetic object (220) configured to be coupled with a base (104) and to at least partially encircle the second permanent magnet (120), wherein at least one of the first and second magnetic objects (210, 220) is a permanent magnet, the first and second magnetic objects (210, 220) configured to be arranged to face each other and to cause a second force to the surface having an opposite direction compared with a first force caused by the first and second permanent magnets (110, 120) to the surface (102).

Description

TRANSDUCER ARRANGEMENT

FIELD

The invention relates to transducers, such as loudspeakers, for converting electrical energy into vibration.

BACKGROUND

Transducers may convert energy from one form to another and are applied in devices like the loudspeakers. Loudspeakers are widely used in many different places to produce a sound. An application WO 2016/079385 discloses a loudspeaker apparatus. The loudspeaker apparatus comprises a first magnet coupled with a surface and a second magnet coupled with a base. The loudspeaker apparatus further comprises at least one supporting member. The first magnet, the second magnet and the supporting member keep the surface in an equilibrium state. The first and the second magnets are arranged to face each other and a coil is arranged between the magnets to generate a force when an electrical signal is fed into the coil. The force breaks the equilibrium state of the surface. It may be beneficial to provide further solutions that are applicable to the described arrangement.

BRIEF DESCRIPTION

The present invention provides an arrangement for producing vibration. According to an aspect of the present invention, there is provided the arrangement as specified in claim 1, wherein a first magnet coupled with a surface and a second magnet coupled with a base are arranged to face each other.

The arrangement further comprises a first magnetic object coupled with the ~ surface and a second magnetic object coupled with the base arranged to face each

N 25 other. The first magnet and the second magnet together with the first magnetic

O object and the second magnetic object may enable the surface to be in a force 0 equilibrium state which may be broken by an input signal to coil of the r arrangement.

E According to an aspect, there is provided the method of claim 15.

I 30 Some embodiments are described in the dependent claims.

LO

= BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention will be described in greater detail by means of preferred embodiments with reference to the attached drawings, in which

Figure 1 illustrates a cross sectional view of an arrangement to which embodiments of the invention may be applied;

Figure 2 illustrates a cross sectional view of an embodiment;

Figure 3 illustrates a cross sectional view of an embodiment;

Figure 4A and 4B illustrate some embodiments;

Figure 5A and 5B illustrate a cross sectional view of some embodiments;

Figure 6A and 6B illustrate a top view of an arrangement according some embodiments;

Figure 7A, 7B and 7C illustrate some embodiments;

Figure 8 illustrates an embodiment;

Figure 9 illustrates a flow diagram according to an embodiment; and

Figure 10 illustrates an arrangement according to an embodiment.

DETAILED DESCRIPTION

The following embodiments are exemplifying. Although the specification may refer to “an”, “one”, or “some” embodiment(s) in several locations of the text, this does not necessarily mean that each reference is made to the same embodiment(s), or that a particular feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.

W02016079385 is incorporated herein as reference.

Figure 1 shows an arrangement 10 for generating vibration, such as haptic output or audio output. Referring to Figure 1, the arrangement 10 comprises: a surface 102 arranged to be mechanically displaced, a first magnet = 110 coupled with the surface 102, at least one supporting member 108 for

N supporting the surface 102, a base 104, a second magnet 120 coupled with the = base 104, wherein the second magnet 120 is arranged to face the first magnet 110 a as shown in Figure 1. The arrangement 10 may further comprise a coil 122

E 30 arranged between the first and second magnets 110, 120, and an input 130 (e.g. a signal port) electrically coupled with the coil 122, wherein an electrical signal is

S configured to travel between the signal port 130 and the coil 122. A magnetic field ™~ between the first magnet 110 and the second magnet 120 causes a force to the

N surface 102, wherein an entity, comprising the surface 102 and the at least one supporting member 108, comprises at least one elastic element providing a supporting counterforce acting as a counterforce to the force caused by the magnetic field, causing the surface 102 to be in a force equilibrium state, and wherein the electrical signal in the coil 122 is proportional to mechanic displacement of the surface 102 when the force equilibrium state is broken either — by the electrical signal in the coil 122 or the mechanic displacement of the surface 102 from a position of the force equilibrium state. That is, when an electrical signal is fed via the input 130 to the coil 122, the force equilibrium may be broken. Hence, the surface 102 may be caused to vibrate (indicated with arrow 103) according to the electrical input signal. It is further noted that the surface 102 may be supported by the at least one supporting member 108, e.g. the surface 102 may be coupled with the at least one supporting member from area(s) 101.

For example, the surface 102 may thus be supported with respect to the base 104 (e.g. the member(s) 108 may be comprised in the base 104). For example, the arrangement 10 may be for generating an audio output according to the electrical inputsignal. Audio output may mean and/or comprise sound that is detectable by human ear, i.e. sound that may be heard by a human. In some examples, it may 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 and the like. It is also pointed out that the surface 102 and the base 104 — may be parts of an apparatus, such as a mobile phone, television, computer, music player, or some other type of user device. For example, the base 104 may form at least a part of a frame of the apparatus. For example, the surface 102 may be or be comprised in a screen of the apparatus (e.g. electronic apparatus). For example, the provide solution may be applicable to automotive industry (e.g. cars). For example, the surface 102 may comprise car panels such as car interior panel (e.g.

U door panel, ceiling or roof panel, wall panel, frame panel, or some other part of

S the car interior. For example, the surface 102 may comprise car display.

O There is provided a further solution which may be applicable for the

Tr arrangement 10 of Figure 1. Said further solution is discussed now in more detail.

N 30 Figure 2 illustrates an embodiment. Referring to Figure 2, an arrangement 100 for

E generating vibration according to an electrical input signal is shown. The

AN arrangement 100 comprises: the first permanent magnet 110 configured to be

S coupled with the surface 102 of an apparatus; the second permanent magnet 120 = configured to be coupled with the base 104 of the apparatus, the first and second

N 35 permanent magnets 110, 120 configured to be arranged to face each other and to cause a first force to the surface 102; and the coil 122 arranged between the first and second permanent magnets 110, 120 and coupled with the input 130 for receiving an electrical input signal, the coil 122 configured to generate a magnetic field according to the electrical input signal in order to displace the surface 102 to generate vibration (e.g. shown in Figure 1 with arrows 103). The arrangement 100 further comprises a first magnetic object 210 configured to be coupled with the surface 102, and a second magnetic object 220 configured to be coupled with the base 104. The first and second magnetic objects 210, 220 are configured to be arranged to face each other and to cause a second force to the surface 102 having an opposite direction compared with the first force (i.e. force caused by the first and second permanent magnets 110, 120 to the surface 102). Hence, the second force may further be used to acquire the force equilibrium state discussed with respect to Figure 1. This may provide additional benefits. For example, the strain on the surface 102 may be reduce as the opposing force may be inflicted to the surface in a more even manner compared with a solution where the counterforce is inflicted from edge areas of the surface 102. Such counterforce may cause bending of the surface 102 which may be reduced by using the objects 210, 220 as described. Another benefit may be that stronger permanent magnets 110, 120 may be used as there is possibility to provide a counterforce to the stronger permanent magnets. It is also pointed out that the bending of the surface 102 may also produce counterforce, and can be used to provide at least some of the counterforce in some embodiments.

In an alternative embodiment, the coil 122 is placed between the magnetic objects 210, 220 instead of placement between the permanent magnets 110, 120.

As shown in Figures 1 and 2, the permanent magnets 110, 120 may be

U arranged to be at a distance from each other. Similarly, the objects 210, 220 may 5 be arranged to be at a distance from each other. This may enable the surface 102 5 to vibrate according to the signal in the coil 122. It is also pointed out that the

Tr surface 102 may be at a distance from the base 104 from at least some areas. 1.e.

N 30 — the surface 102 is hangably arranged, pre-tensioned and/or otherwise arranged

E such that it may vibrate.

AN To further enhance the solution, the placement of the first and second

S magnetic objects 210, 220 may be such that the first magnetic object 210 at least = partially encircles and/or surrounds the first permanent magnet 110, and the

N 35 second magnetic object 220 at least partially encircles and/or surrounds the second permanent magnet 120. The encircling may be such that the object 210,

220 fully encircles the corresponding magnet or at least extends to opposite sides of the respective magnet (i.e. permanent magnet 110, 120 is placed between at least two portions of the respective magnetic object 210, 220). It is also possible that the magnetic object 210, 220 is made of pieces which at least partially 5 encircle the respective permanent magnet 110, 120, meaning that not all parts of the magnetic objects 210, 220 are necessarily magnetic.

There are different possibilities to achieve the second force (also referred to as counterforce) cause by the magnetic interaction between the first and second magnetic objects 210, 220. In one example at least one of the first and — second magnetic objects 210, 220 is a permanent magnet (e.g. one is permanent magnet and other comprises magnetic material or both are permanent magnets).

It is noted that the first magnetic object 210 may be placed at a distance from the first permanent magnet 110 as shown in Figure 2. Similarly, there may be a certain gap between second magnetic object 220 and the second permanent magnet 120. Using the gap therebetween may reduce the interaction of magnetic forces between the second permanent magnet 120 and the first magnetic object 210, for example. Similarly, the gap may reduce the interaction of magnetic forces between the first permanent magnet 110 and the second magnetic object 220. Therefore, using the gap may further improve the provided — solution. The distance or gap between the first magnetic object 210 and the first permanent magnet 110 and/or between the second magnetic object 220 and the second permanent magnet 120 may be, for example, at least 1 centimetre (cm), 2 cm, 3 cm, 4 cm, 5 cm, 10 cm or more. The gap may refer to air gap or some other gas, or may comprise some substantially non-magnetic material. As discussed later, magnetic material may also be used between the magnets and magnetic

U objects.

S It is noted that the coupling of a magnet or magnetic object with the

O surface 102 or the base 104 may refer to fixing or attaching said magnetic or

Tr magnetic object to the surface 102 or the base 104. Such fixing may be achieved

N 30 using, for example, glue and/or screws. In some examples, the different magnet(s)

E and/or magnetic object(s) may be printed on the surface 102 and/or the base

N 104. Hence, the coupling may also comprise printing (e.g. electronics printing). 2 Further, the arrangement of the coil 122 between the permanent magnets 110, = 120 may comprise coupling (e.g. fixing or attaching) the coil 122 with the second

N 35 permanent magnet 120 or with the first permanent magnet 110. However, it may also be possible to use separate elements to arrange the coil 122 between the permanent magnets 110, 120 such that it does not physically touch neither of said permanent magnets 110, 120. For example, said element(s) may be attached to the base 104 or some other part of the arrangement, and reach to the area between the permanent magnets 110, 120. Similar, attachment with respect to possibly used further coil (e.g. coil 722) may be used.

Also, the surface 102 may be supported with respect to the base 104 using a plurality of different solutions. For example, one or more elastic and/or flexible elements may be used to support the surface 102. In one example, the one or more elastic and/or flexible elements comprise spring(s) disposed between — the surface 102 and the base 104. However, these may not necessarily be needed as the counterforce may be partially or entirely achieved using the magnetic objects 210, 220. Hence, these one or more elastic and/or flexible elements are not discussed in further detail. It may suffice that the surface 102 may be supported from at least one area 101 with respect to the base 104 (e.g. edge area 101 of the surface 102, such asa screen). The supporting on the area(s) 101 may be at least partially elastic and/or comprise clearance such that the surface 102 may move also from the edge areas with respect to the base 104 according to the electronic signal inputted via the input 130 to the coil 122.

According to an embodiment, the provided arrangement comprises one or more elastic elements (e.g. springs) disposed between the elements 310 and 320 (e.g. fixed to both elements to provide the counterforce). Similarly, in cases where only two magnets are used (e.g. magnets 110, 120) the springs may be arranged between bases coupled (e.g. fixed) with the magnets. So, for example, magnet 110 may comprise or be coupled with a base. So, for example, magnet 120 may comprise or be coupled with a base. Hence, the springs or similar elements

U may be connected to said bases. So, as described, the arrangements does not 5 initially necessarily reguire the surface 102 and the base 104, but may be 5 arranged in such system or apparatus comprising the surface 102 and the base

Tr 104 with minimum effort as the arrangement may already be configured to be in

N 30 equilibrium state.

E It is also pointed out that the surface 102 may be rigid (i.e. bends very

N little or not at all, e.g. inflexible). The surface 102 may comprise, for example, a 2 plane. The surface 102 may comprise, for example, metal, wood, glass, and/or = plastics. In an embodiment, the thickness of the surface is at least 0.5 cm. In an

N 35 embodiment, the thickness of the surface is at least 1 cm. In an embodiment, the thickness of the surface is at least 2 cm. In an embodiment, the thickness of the surface is atleast 5 cm.

Figure 3 shows the arrangement 100 according to an embodiment.

Referring to Figure 3, the first and second magnetic objects 210, 220 each comprise a permanent magnet 211, 221. The number of permanent magnets is notnecessarily limited to two, but two may suffice at least in some examples (e.g. ring magnets). In the example of Figure 3, the first and second permanent magnets 110, 120 cause a force that pushes the magnets 110, 120 away from each other). However, the first and second magnetic objects 210, 220 (or more precisely their permanent magnets 211, 221) are placed such that they pull each — other. Hence, the overall force to the surface 102 may be sum of said two pushing and pulling forces. Naturally, the forces may be arranged other way around (i.e. permanent magnets 110, 120 pull each other and permanent magnets 211, 221 push each other).

Previously, it was discussed that there may be a gap between the magnetic object 210 and the permanent magnet 110, and similarly, between the magnetic object 220 and the permanent magnet 120. In an embodiment, the arrangement 100 further comprises at least one further element 310, 320 comprising magnetic material. For example, a first further element 310 may be arranged between the first permanent magnet 110 and between the permanent magnet 211 of the first magnetic object 210. For example, a second further element 320 may be arranged between the second permanent magnet 120 and the permanent magnet 221 of the second magnetic object 220. The at least one further element 310, 320 may act as a buffer between the magnets 211, 110, and between the magnets 221, 120. Buffer here may mean that the magnetic interaction reduced using the gap described earlier may be further reduced using

U the at least one further element 310, 320 between the permanent magnets.

S Hence, there may be no need for the gap(s), and thus smaller devices may be

O achieved. However, in addition to the at least one further element 310, 320, the

Tr gap or gaps between the magnets may be used. For example, the at least one

N 30 further element 310, 320 comprises and/or is made of ferromagnetic and/or

E ferrimagnetic material(s), such as iron.

N In an embodiment, the first magnetic object 210 is coupled (e.g. 2 attached or fixed) to the first element 310. = In an embodiment, the second magnetic object 220 is coupled (e.g.

N 35 attached or fixed) to the second element 320.

In an embodiment, the first permanent magnet 110 is coupled (e.g.

attached or fixed) to the first element 310.

In an embodiment, the second permanent magnet 120 is coupled (e.g. attached or fixed) to the second element 320.

In an embodiment, the at least one further element 310, 320 comprises a core of an axially magnetized permanent ring magnet comprised in the first magnetic object 210 and/or the second magnetic object 220. For example, the first element 310 may form the core of an axially magnetized permanent ring magnet 211. For example, the second element 310 may form the core of an axially magnetized permanent ring magnet 221.

In an embodiment, the at least one further element 310, 320 comprises a cavity for the first permanent magnet 110 and/or the second permanent magnet 120. This may be shown in Figure 3 in which the first permanent magnet 110 may be placed in a cavity of the first element 310 forming the core of the ring magnet 211. Similarly, the second permanent magnet 120 may be placed in a cavity of the second element 320 forming the core of the ring magnet 221. The coil 122 may reach to the area of the at least one further element 310, 320 (e.g. between elements 310, 320). However, this may not be necessary.

Figures 4A and 4B show some examples of different arrangements of the permanent magnets and/or magnetic objects. For example, with reference to

Figure 4A, if the north poles of permanent magnets 110, 120 are placed to face each other, the magnetic objects 210, 220 may be arranged such that other provides a south pole and the other provides a north pole that are facing each other. Hence, the first force and the second force may be to opposite directions.

With reference to Figure 4B, the second permanent magnet 120 is flipped and — thus there is a pulling force between the magnets 110, 120. Hence, it may be

U necessary to arrange at least one of the magnetic objects 210, 220 to achieve the 5 opposing force therebetween. 5 Use of permanent magnets 211, 221 may not be necessary in all cases.

Tr Examples of such configurations may be shown in Figures 5A and 5B illustrating

N 30 some embodiments. Referring to Figures 5A and 5B, the first magnetic object 210

E or the second magnetic object 220 may comprise an element 510 or 520. Said

AN element(s) 510, 520 may be made of and/or magnetic material, such as

S ferromagnetic and/or ferrimagnetic material. Hence, if the other one of the first = and second magnetic objects 210, 220 comprises a permanent magnet, the

N 35 element 510, 520 may be used to provide the counterforce similarly as in the situation where both magnetic objects 210, 220 comprise permanent magnets.

According to an embodiment (referring to Figure 5A), a first pole of the first permanent magnet 110 faces the second permanent magnet 120, wherein a second pole of the first permanent magnet 110 is fixed to the first magnetic object 210 to magnetize the first magnetic object 210 (or more particularly the element 510) facing the second magnetic object 220. In such case the second magnetic object 220 may comprise a permanent magnet (e.g. permanent magnet 221 as shown in Figure 5A, for example.

According to an embodiment (referring to Figure 5B), a first pole of the second permanent magnet 120 is arranged to face the first permanent magnet 110, wherein a second pole of the second permanent magnet 120 is fixed to the second magnetic object 220 to magnetize the second magnetic object 220 (or more particularly the element 520) facing the first magnetic object 210. In such case the first magnetic object 210 may comprise a permanent magnet (e.g. permanent magnet 211 as shown in Figure 5B), for example. For example, first — pole may be north and second pole may be south. Other way around, first pole may be south and second pole may be north. In the Figures (e.g. Figures 5A and 5B) one magnetic pole (e.g. first pole) may be indicated with a pattern fill comprising backslashes and the other magnetic pole (e.g. second pole) is indicated with a pattern fill comprising slashes or solidus.

As shown in Figures 5A and 5B, if the magnetic object 210, 220 is magnetized using the permanent magnet 110, 120, said magnetic object 210, 220 may be referred to as a magnetized element 510, 520 (i.e. magnetic object 210 is element 510 and magnetic object 220 is element 520). Accordingly, areas 512, 522 may be magnetized such that they enable to provide the counterforce. For example with reference to Figure 54, if same poles of first and second permanent

U magnets 110, 120 are facing each other, the magnetized element 510 is drawn to 5 the magnet 221 from the area 512 as the area 512 may be magnetized with the 5 opposing pole (i.e. opposing to the pole facing the second permanent magnet 120)

Tr of the first permanent magnet 110. Similarly, the area(s) 522 of Figure 5B may be

N 30 magnetized according to the same principles. So, for example, in Figure 5A, areas

E 512 may be magnetized such that they represent second pole (i.e. backslash filled

AN portions).

S It is further noted that the element 510, 520 may comprise a cavity for = the permanent magnet 110, 120. It is further noted that said cavity may be such

N 35 that the elongating area or areas 512, 522 are not in direct contact with the permanent magnet 110, 120 (as shown in Figure 5B). Hence, the element 510,

520 and the permanent magnet 110, 120 may be arranged such that only one pole of said permanent magnet 110, 120 is in direct contact with the element 510, 520, and thus the element 510, 520 may be magnetized with the needed pole (i.e. the same pole which is in contact with the permanent magnet 110, 120).

Figures 6A and 6B illustrate birds-eye view of the arrangement 100 according to some embodiments. Referring to Figure 6A, a magnetic object 610 encircles a permanent magnet 630. The magnetic object 610 may refer to one or both the first magnetic object 210 and the second magnetic object 220.

Correspondingly, the permanent magnet 630 may refer to one or both the first permanent magnet 110 and the second permanent magnet 120. It needs to be noted that the encircling magnetic object 610 may be fully or partially magnetic as discussed above.

In an embodiment, the magnetic object 610 comprises an axially magnetized permanent ring magnet. That is, the ring magnet may encircle the permanent magnet 630.

In an embodiment, with reference to Figure 6A, a further magnetic element 620 may be placed between the object 610 and the permanent magnet 630. Said further element 620 may refer to one or both the element 310 and the element 320 of Figure 3. According to one embodiment, the element 620 forms a core of the axially magnetized permanent ring magnet (i.e. comprised or forming element 610). The element 620 may further comprise a cavity or a slot for the permanent magnet 630. Thus, the permanent magnet 630 may be embedded into the element 620, and the element 620 may be embedded into the ring magnet (i.e. comprised or forming element 610).

Referring to Figure 6B, situation illustrated and discussed with respect

U to Figures 5A and 5B may be shown. That is, the permanent magnet 630 may be

S encircled by an element 640 (e.g. comprise ferromagnetic material) which may be

O magnetized by said permanent magnet 630. As described, there may be a gap 650

Tr between the permanent magnet 630 and the element 640, the gap 650 enabling

N 30 — the permanent magnet 630 to be in contact with the element 640 via only one

E pole of the permanent magnet 630. Said element 640 may refer to one or both

N the element 510 and element 520 of Figures 5A and 5B.

S In an embodiment, the permanent magnet 630 is a disc magnet, i.e. = axially magnetized permanent disc magnet 630.

N 35 For example, the element 620 may be a cylinder with a cylindrical cavity, wherein the disc magnet 630 may be placed in said cylindrical cavity. Said cavity may as well be rectangular, wherein the magnet 630 may thus be rectangular. The object 610 may surround the element 620. In an embodiment, the object 610 is a cylinder (or of some other form) with a cylindrical cavity (or of some other form), wherein the element 620 may be placed in a cavity formed by said object 610.

Figures 7A to 7C illustrate some embodiments. According to an embodiment, the arrangement 100 further comprises a second coil 722 arranged between the first and second magnetic objects 210, 220 and configured to generate a second magnetic field according to an electrical input signal. The coil 122 (now referred to as a first coil 122) and the second coil 722 may be coupled with the same input 130 or with different inputs. Hence, the arrangement 100 may be used in a plurality of different ways to generate different magnetic fields in order to displace the surface 102 to generate vibration. If there is no input via the input 130 and/or some other input, the surface 102 may be in a force equilibrium state. However, when input is provided to the coil(s) 122, 722, the equilibrium state may be broken. The second coil 722 may be coupled with the second magnetic object 220. However, it may be coupled to the first magnetic object 210 or otherwise arranged between said objects 210, 220.

Now, according to an embodiment, the coils 122, 722 are connected to — the same input 130 (e.g. Figure 7A). That is, same, identical or similar electrical input signal may be simultaneously inputted to both coils 122, 722. According to an alternative embodiment, a different electrical signals may be inputted to both coils 122, 722 and/or the input signal(s) may be inputted at different time periods.

According to an embodiment, arrangement 100, the coils 122, 722

U and/or the input 130 is arranged such that when the magnetic fields generated by 5 the coils 122, 722 both cause a force to the surface 102 that is substantially to the 5 same direction (e.g. towards the base 104 or outwards from the base 104). There

Tr may be plurality of different ways to achieve this. However, there may be at least

N 30 — two solutions which may be used.

E Referring to Figure 7B, the arrangement 100 further comprises a

AN phase shifter 720 for shifting a phase of an electrical input signal such that a

S phase of the electrical input signal inputted into the first coil 122 is substantially = 180 degrees different compared with a phase of an electrical input signal inputted

N 35 into the second coil 722. That is, if same or similar signal is used as an input, before the signal is inputted in the coils 122, 722, the signal may be processed or altered (e.g. analogic and/or digital processing) such that the inputted signals to the coils are in antiphase with respect to each other. One example of such processing may be delaying the phase of the input signal to the second coil 722.

Referring to Figure 7C, a winding of the first coil 122 may be opposite to a winding of the second coil 722. E.g. if the winding of the first coil 122 is to direction 750, the winding of the second coil 722 may be to opposite direction 760. Hence, if an input signal having the same phase is inputted in to both coils 122, 722, the coils may provide magnetic fields which are (at least) to substantially different directions, i.e. same or identical input signal is configured to be inputted to both coils 122, 722. It is noted that the throughout the description, phrases like input signal or electrical input signal is used. Such may refer to an electrical input signal which has an alternating current (AC) component. Said signal may or may not have a direct current (DC) component.

However, as generally known, the alternating current in a coil may cause the magnetic field. This is generally referred to as electromagnet functionality.

The coil(s) 122, 722 may be placed between the magnets 110, 120 and the magnetic objects 210, 220 such that the main force component caused, by the input signal(s), to the surface is substantially orthogonally towards or away from the base. E.g. the winding may be placed on the magnet 120 or object 220 as shown in Figure 7C illustrating top view of the coils 122, 722.

In an embodiment, the coil(s) 122, 722 have a core, such as an iron core. Said core may be orthogonal to the magnet 120 or the object 220 when the coil 122 or the second coil 722 is placed on said magnet 120 or on said object 220.

In an embodiment, the first and second forces are of substantially equal magnitude. That is, the magnetic objects 210, 220 and the permanent

U magnets 110, 120 may be arranged, dimensioned and configured such that the 5 forces are substantially egual. Hence, the strain to the surface 102 may further be 5 reduced when the surface 102 is in the force equilibrium state. If the forces are

Tr unequal magnitude, the equilibrium state may be achieved using elastic elements

N 30 (e.g. 108) and/or relying on the spring force caused by the bending surface 102.

E In an embodiment, the coil 722 is attached to a permanent magnet of

AN the second magnetic object 220 or a permanent magnet of the first magnetic

S object 210. For example, the coil 722 may be used in embodiments utilizing = permanent magnet at both the first and second magnetic objects 210, 220 (e.g.

N 35 Fig. 3) and embodiments utilizing one permanent magnet and one magnetized element (e.g. Figs. 5A and 5B).

It is further noted that although not shown in Figure 7C, the coils 122, 722 may be connected from other ends to ground potential such that a closed electrical circuit or circuits may be formed. This is believed to be well within capability of a skilled person and thus not explained in further detail.

Figure 8 illustrates an embodiment. Referring to Figure, an apparatus 800 is shown. The apparatus 800 may comprise the surface 102 (e.g. a display of the apparatus 800) and the base 104 (not shown in Figure 8). Furthermore, the apparatus 800 may comprise at least one arrangement 100 as described above and/or below. The arrangement 100 is illustrated as arrangement 810A and 810B in Figure 8. Using the arrangement(s) 100 in the apparatus 800 may remove the need to use an additional vibration element and/or speaker. Hence, there may be more room in the device for display, for example. Such may be a beneficial feature, for example, for mobile phones, televisions and the like.

Figure 9 illustrates a flow diagram of a method of manufacturing an arrangement 100 generating vibration according to an electrical input signal, the method comprising: coupling a first permanent magnet with a surface of an apparatus (block 902); coupling a second permanent magnet with a base of the apparatus, the first and second permanent magnets arranged to face each other and to cause a first force to the surface (block 904); arranging a coil between the — first and second permanent magnets, the coil coupled with an input for receiving an electrical input signal, the coil configured to generate a magnetic field according to the electrical input signal in order to displace the surface to generate vibration (block 906); coupling a first magnetic object with the surface such that the first magnetic object at least partially encircles the first permanent magnet (block 908); coupling a second magnetic object with the base such that the second

U magnetic object at least partially encircles the second permanent magnet (block 5 910), wherein at least one of the first and second magnetic objects comprises a 5 permanent magnet, the first and second magnetic objects arranged to face each

Tr other and to cause a second force to the surface having an opposite direction

N 30 compared with the first force.

E Figure 10 illustrates the arrangement 100 according to an

AN embodiment. As shown in the Figure, the arrangement 100 does not necessarily

S comprise the surface 102 and the base 104. However, the arrangement 100 may = be arranged such that the arrangement 100 is attachable to the surface 102 and to

N 35 the base 104. Although in Figure 10 four permanent magnets are shown (i.e. 110, 120, 211, 221), the solution may be similarly applicable to solutions utilizing less permanent magnets (e.g. Figs 5A and 5B). For example, the magnets 120 and 221 may be attached to each other via the element 320, and the coil 122 may attached to the formed first entity. A second entity may be formed by attaching the magnets 211 and 110 to each other via the element 310. The second entity may then be attached to the surface 102 and the first entity to the base 104, for example. In some cases, the attachment may be other way around (i.e. first entity may be attached to the surface 102. It is also possible that the coil 722 is used in the embodiment of Fig. 10 (i.e. examples of Figs. 7A to 7C). Also, the springs or some other elastic elements (if used at all) may be arranged directly between the firstand second entities (e.g. attached between said entities). Hence, the assembly comprising the first and second entities may be easily attached to a surface and a base of an apparatus to obtain a vibrating (e.g. sound generating apparatus.

As used in this application, ferromagnetic materials may comprise at least one of cobalt, iron, nickel, gadolinium, dysprosium, permalloy, awaruite, wairakite, and magnetite. In some embodiments, the ferromagnetic materials comprise two or more of said materials. For example, the permanent magnets described above may be made of and/or comprise the described materials.

In an embodiment, the first magnet 110 and/or the second magnet 120 are made and/or comprise neodymium and/or ferrite. In such case, the kJ/m?® value of the first and/or second magnets 110, 120 may be between 250 - 400 kJ /m?, for example. Similarly, the other permanent magnets described above may comprise said material(s). Even though the invention has been described above with reference to an example according to the accompanying drawings, it is clear that the invention is not restricted thereto but can be modified in several ways within the scope of the appended claims. Therefore, all words and

U expressions should be interpreted broadly and they are intended to illustrate, not 5 to restrict, the embodiment. It will be obvious to a person skilled in the art that, as 5 the technology advances, the inventive concept can be implemented in various

Tr ways. The invention and its embodiments are not limited to the examples

N 30 described above but may vary within the scope of the claims.

E

5 2

N

Claims (15)

1. An arrangement (100) for generating vibration according to an electrical input signal, the arrangement comprising: a first permanent magnet (110) configured to be coupled with a surface (102) of an apparatus; a second permanent magnet (120) configured to be coupled with a base (104) of the apparatus, the first and second permanent magnets (110, 120) configured to be arranged to face each other and to cause a first force to the surface (102); and a coil (122) arranged between the first and second permanent magnets (110, 120) and coupled with an input (130) for receiving an electrical input signal, the coil (122) configured to generate a magnetic field according to the electrical input signal in order to displace the surface (102) to generate vibration, characterize d by the arrangement further comprising: a first magnetic object (210) configured to be coupled with the surface (102) and to at least partially encircle the first permanent magnet (110); and a second magnetic object (220) configured to be coupled with the base (104) and to at least partially encircle the second permanent magnet (120), wherein at least one of the first and second magnetic objects (210, 220) comprises a permanent magnet, the first and second magnetic objects (210, 220) configured to be arranged to face each other and to cause a second force to the surface having an opposite direction compared with the first force.

2. The arrangement of claim 1, wherein the arrangement (100) is for = generating an audio output according to the electrical input signal. N

S

3. The arrangement of claim 1 or 2, wherein the second magnetic 2 object (220) comprises a permanent magnet. Ek 30 a

4. The arrangement of any preceding claim, wherein the first magnetic > object (210) comprises a permanent magnet. =

N

5. The arrangement of claim 3, wherein a first pole of the first permanent magnet (110) faces the second permanent magnet (120), and wherein a second pole of the first permanent magnet (110) is fixed to the first magnetic object (210) to magnetize the first magnetic object (210) facing the second magnetic object (220).

6. The arrangement of any preceding claim, wherein the first magnetic object (210) encircles the first permanent magnet (110) and the second magnetic object (220) encircles the second permanent magnet (120), and wherein at least one of the first magnetic object (210), the second magnetic object (220) comprises an axially magnetized permanent ring magnet.

7. The arrangement of any preceding claim, wherein said coil (122) is a first coil (122) configured to generate a first magnetic field according to the electrical input signal, the arrangement further comprising: a second coil (722) arranged between the first and second magnetic objects and configured to generate a second magnetic field according to an electrical input signal.

8. The arrangement of claim 7, further comprising: means (720) for shifting phase of the electrical input signal such thata phase of the of the electrical input signal inputted into the first coil (122) is substantially 180 degrees different compared with a phase of the electrical input signal inputted into the second coil (722).

9. The arrangement of claim 7, wherein a winding of the first coil (122) is opposite to a winding of the second coil (722). 00 S

10. The arrangement of any preceding claim, the arrangement further 3 comprising: ? at least one further element (310, 320) comprising magnetic material > 30 and arranged between the first permanent magnet (110) and a permanent E magnet of the first magnetic object (210) and/or between the second permanent N magnet (120) and a permanent magnet of the second magnetic object (220). D =

11. The arrangement of claim 10, wherein the at least one further N 35 element (310, 320) comprises a core of an axially magnetized permanent ring magnet comprised in the first magnetic object and/or the second magnetic object.

12. The arrangement of claim 11, wherein the at least one further element comprises (310, 320) a cavity for the first permanent magnet and/or the second permanent magnet.

13. The arrangement of any preceding claim, wherein the first and second forces are of substantially equal magnitude.

14. An apparatus (800) comprising: a surface (102); a base (104); and at least one arrangement (100) according to any of claims 1 to 13.

15. A method of manufacturing an arrangement (100) generating vibration according to an electrical input signal, the method comprising: coupling (902) a first permanent magnet with a surface of an apparatus; coupling (904) a second permanent magnet with a base of the apparatus, the first and second permanent magnets arranged to face each other and to cause a first force to the surface; arranging (906) a coil between the first and second permanent magnets, the coil coupled with an input for receiving an electrical input signal, the coil configured to generate a magnetic field according to the electrical input signal in order to displace the surface to generate vibration; characterized by the method further comprising: © coupling (908) a first magnetic object with the surface such that the S first magnetic object at least partially encircles the first permanent magnet; 3 coupling (910) a second magnetic object with the base such that the ? second magnetic object at least partially encircles the second permanent magnet, > 30 wherein at least one of the first and second magnetic objects E comprises a permanent magnet, the first and second magnetic objects arranged to AN face each other and to cause a second force to the surface having an opposite S direction compared with the first force. 3 N 35