COMPRISING SAID MAGNET ACTUATOR

TECHNICAL FIELD

The disclosure relates to a magnet actuator for use in an electronic device, the magnet actuator comprising a coil, a magnet, a first housing and a second housing.

BACKGROUND

Electronic devices may be provided with magnet actuators in order to generate, e.g., sound waves. Prior art magnet actuators comprise magnets which either attract or repulse each other. Initially, the magnets are arranged in force equilibrium, but in order to generate sound waves the attractive or repulsive force between the magnets is changed by means of an electric current passing through a coil located between the magnets, the current causing at least one of the magnets to move such that the distance between the magnets decreases or increases.

As disclosed in GB2532436, the magnets may be interconnected by means of resilient support elements which counteract the attractive or repulsive force between the magnets such that the magnets and the resilient support element are in a force equilibrium state as long as no current is supplied. The different components of the magnet actuator of GB2532436 are integrated into the device structure and arranged between the main elements of the device. The appearance of the assembled electronic device can be assessed only after the force equilibrium state has been reached, i.e. after the main elements of the device have been assembled. Any possible defects, caused by dimensional tolerance variations of each separate element in the structure, variations in force between the magnets, or variations in the force caused by the resilient support element, will be visible only after assembly, and will subsequently be time consuming and costly to repair.

SUMMARY

It is an object to provide an improved magnet actuator. The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description, and the figures .

According to a first aspect, there is provided a magnet actuator for use in an electronic device, the magnet actuator comprising a coil, a magnet, a first housing and a second housing, the coil being at least partially located within, and fixed to, the first housing, the magnet being at least partially located within, and fixed to, the second housing, the first housing comprising a magnetic material, a magnetic field, generated by the magnet and the first housing causing an attractive force between the magnet and the first housing, the magnet and the first housing being in a force equilibrium state, wherein an air gap is provided between the magnet and the coil, and wherein manipulating electrical current in the coil causes a change in the attractive force, thereby causing a displacement between the magnet and the first housing.

A magnet actuator such as this, wherein a magnet and a housing are in a force equilibrium state facilitates the manufacture of the electronic device in which the magnet actuator is placed. The attractive force caused by the magnet and the housing are balanced from the start, such that the other components of the electronic device remain unaffected by, e.g., variations in the force or dimensional variation of the different components of the magnet actuator. Such a solution reduces the number of defective electronic devices and hence manufacturing and repair costs. It is to be pointed out that in an implementation form of the first aspect the magnet actuator comprises exactly one magnet. I.e. the magnet actuator does not comprise a further magnet than the one mentioned .

In a possible implementation form of the first aspect, the magnet actuator further comprises at least one spacer, the spacer being arranged to maintain the magnet and the first housing in a force equilibrium state by acting as a counterforce to the force caused by the magnetic field, allowing the magnet and the coil to be separated by an even air gap at all times.

In a further possible implementation form of the first aspect, the spacer is adapted for providing a first air gap between the magnet and the coil when the magnet actuator is in a first actuating end position, and a second air gap, smaller than the first air gap, between the magnet and the coil when the magnet actuator is in a second actuating end position, providing a space efficient magnet arrangement.

In a further possible implementation form of the first aspect, the spacer interconnects at least one of the first housing and the second housing, and the first housing and the magnet, allowing the magnet actuator to be configured as one integral component which is easily mounted in an electronic device.

In a further possible implementation form of the first aspect, the spacer is compressible and fixed to an inner surface of the first housing, the spacer being in an uncompressed state when the magnet actuator is in the first actuating end position, and the spacer being in a compressed state when the magnet actuator is in any position other than the first actuating end position, including the second actuating end position, facilitating a sufficiently strong yet spatially efficient magnet actuator.

In a further possible implementation form of the first aspect, the spacer comprises a flexible gasket.

In a further possible implementation form of the first aspect, the spacer comprises a dust shield connected to the first housing and the second housing, covering a gap between the first housing and the second housing, preventing dust

and other particles from entering the actuator and

interfering with the function of the same.

In a further possible implementation form of the first aspect, the spacer comprises a flexible gasket and a dust shield .

In a further possible implementation form of the first aspect, the first housing and the second housing guide the magnetic field to a space within at least one of the first housing and the second housing, preventing the magnetic fields from interfering with other objects.

In a further possible implementation form of the first aspect, the first housing and the second housing have an open end and a closed base connected by a surrounding wall, an inner periphery of one of the first housing and the second housing substantially corresponding to an outer periphery of the other of the first housing and the second housing, with allowance for movement between the first housing and the second housing, which is a simple yet reliable construction which provides sufficient protection for the magnet arrangement as well as efficiently limits the magnetic fields to the cavity formed by the first housing and the second housing.

In a further possible implementation form of the first aspect, the first housing and the second housing are partially overlapping, allowing the magnet actuator to be assembled into, and maintained as, one integral part.

In a further possible implementation form of the first aspect, the first housing and the second housing comprise interconnecting flanges which connect when the magnet actuator is in a first actuating end position or a second actuating end position, preventing the components of the magnet actuator from separating regardless of which exterior forces are applied to the magnet actuator.

According to a second aspect, there is provided an electronic device comprising a movable surface, a device chassis, and a magnet actuator according to the above arranged between the movable surface and the device chassis, adapted to move the movable surface relative to the device chassis. The movable surface may be a display of the electronic device. The display can in such case be used as a so called "singing display".

By providing an electronic device with a magnet actuator which is balanced from the start, the other components of the electronic device remain unaffected by, e.g., variations in force or dimensions within the magnet actuator. Such a solution reduces the number of defective electronic devices and hence manufacturing and repair costs.

In a possible implementation form of the second aspect, a first housing of the magnet actuator is attached to the movable surface, and a second housing of the magnet actuator is attached to the device chassis, or a second housing of the magnet actuator is attached to the movable surface and a first housing of the magnet actuator is attached to the device chassis, facilitating a very stable magnet actuator which can withstand large external forces. In a further possible implementation form of the second aspect, movement of the movable surface generates vibrations within the electronic device to be used as haptic means or for generating sound waves.

According to a third aspect, there is provided a kit for assembling a magnet actuator, comprising a magnet actuator according to the above, an assembly pin, a first housing of the magnet actuator comprising a through-going recess for receiving the assembly pin, a first end of the assembly pin being releasably connected to an inner surface of the second housing after having passed through the through-going recess, and a second end of the assembly pin being releasably connected to an outer surface of the first housing, such that the first housing and the second housing are interconnected, and a magnet and a coil maintained at a predefined distance from each other by means of the assembly pin .

Such a solution facilitates the assembly of the magnet actuator by ensuring that the air gap between the magnet and the coil is kept at the desired distance during the entire assembly phase, including while interconnecting the

different components by means of adhesive.

In a possible implementation form of the third aspect, the assembly pin is T-shaped, one leg of the assembly pin extending in the direction of an attractive force caused by a magnetic field within the magnet actuator, when the assembly pin has been received in the through-going recess, and one leg of the assembly pin extending in a plane perpendicular to the direction of the attractive force, facilitating a simple yet stable solution for ensuring that the air gap between the magnet and the coil is kept at the desired distance during assembly.

In a further possible implementation form of the third aspect, at least one of the magnet and a spacer comprises a further through-going recess adapted for accommodating the assembly pin, ensuring that the components of the magnet actuator remain in place during the entire assembly process, including while interconnecting the different components by means of adhesive.

This and other aspects will be apparent from and the embodiments described below.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following detailed portion of the present disclosure, the aspects, embodiments, and implementations will be explained in more detail with reference to the example embodiments shown in the drawings, in which:

Fig. 1 shows an exploded view of a magnet actuator in accordance with an embodiment of the present invention;

Fig. 2a shows a partial, cross-sectional side view of the magnet actuator shown in Fig. 1;

Fig. 2b shows an exaggerated cross-sectional side view of the magnet actuator shown in Fig. 2a, wherein the magnet actuator is in a first actuating end position; Fig. 2c shows an exaggerated cross-sectional side view of the magnet actuator shown in Figs. 2a and 2b, wherein the magnet actuator is in a second actuating end position;

Fig. 3 shows a perspective cross-sectional side view of an electronic device comprising the magnetic actuator shown in Figs. 1 and 2a-2c;

Fig. 4a shows a cross-sectional side view of a magnet actuator in accordance with an embodiment of the present invention;

Fig. 4b shows a side view of the magnet actuator shown in Fig. 4a;

Fig. 5 shows a cross-sectional side view of a magnet actuator in accordance with a further embodiment of the present invention;

Fig. 6 shows a cross-sectional side view of a magnet actuator in accordance with a further embodiment of the present invention;

Fig. 7 shows a schematic cross-sectional side view of a magnet actuator in accordance with a further embodiment of the present invention;

Fig. 8 shows a schematic cross-sectional side view of a magnet actuator in accordance with a further embodiment of the present invention. DETAILED DESCRIPTION

Figs. 1 and 2a-2c show an embodiment of a magnet actuator 1 in accordance with the present disclosure.

The magnet actuator 1 comprises a first housing 5, a second housing 6, a coil 3, and a magnet 4. The coil 3 comprises a plurality of coil windings and is at least partially located within, and fixed to, the first housing 5. In one

embodiment, the coil 3 is fixed to the inner surface 5a of the first housing 5 by means of adhesive. The magnet 4 is at least partially located within, and fixed to, the second housing 6. In one embodiment, the magnet 4 is fixed to the inner surface 6a of the second housing 6 by means of adhesive. In one embodiment magnet actuator 1 comprises exactly one magnet, i.e. the magnet 4. No other magnet is arranged between the housings 5 and 6.

The first housing 5 comprises a magnetic material, such as metal, wherefore the first housing 5 acts as a counterpart to the attractive static force F. Hence, the magnet 4, located within the second housing 6, and the first housing 5 together generate a magnetic field which causes an

attractive force F between the magnet 4 and the magnetic first housing 5, pulling the magnet 4 and the magnetic first housing 5 towards each other and hence also the second housing 6 and the coil 3 towards each other.

The first housing 5 and the second housing 6 guide, as well as limit, the magnetic field to a space within at least one of the first housing 5 and the second housing 6. The magnetic field may be limited by the housing such that it fills the entire space within the housing. The magnetic field may also be guided within the housing such that the magnetic field is at its strongest at a specific location within the housing, e.g. at the air gap described below.

The magnet 4 and the first housing 5 are in a force

equilibrium state as long as there is no electrical current in the coil 3, and due to the equilibrium, a specific air gap 7 can be set to separate the magnet 4 and the coil 3.

Manipulating the electrical current in the coil 3 causes a change in the attractive force F, thereby causing a displacement between the magnet 4 and the first housing 5. By continuously manipulating the electrical current, the displacement is continuous. Hence, any surface connected to either the first housing 5 or the second housing 6 can be made to vibrate .

In one embodiment, the magnet actuator 1 comprises at least one spacer 8. The spacer 8 is arranged to maintain the magnet 4 and the first housing 5 in the force equilibrium state by acting as a counterforce to the attractive force F caused by the magnetic field, and to maintain the size of the air gap, described in more detail below, between the magnet 4 and the coil 3 at a fixed height. Additionally, the spacer 8 prevents the first housing 5 and the second housing 6 from colliding and generating unwanted noise.

However, the force equilibrium state may also be achieved by means of the air gap size, the attractive force F, and the spring force of the surface which the magnet actuator is attached to.

The spacer 8 provides a first air gap 7a, i.e. an air gap having a specific height, between the magnet 4 and the coil 3 when the magnet actuator 1 is in the first actuating end position PI. Fig. 2b shows the magnet actuator 1 in the first actuating end position PI, with exaggerated dimensions for the sake of clarity. Fig. 2a shows a more realistic relationship between the air gap, the magnet, and the coil when the magnet actuator 1 is in the first actuating end position PI. The first actuating end position PI means that the actuator is in its extreme, outer position, the position in which the height of the magnet actuator is as large as possible and where the maximum vibration amplitude is reached during displacement due to electrical current.

The spacer 8 furthermore provides a second air gap 7b, i.e. an air gap which has a smaller height than the first air gap 7a, between the magnet 4 and the coil 3 when the magnet actuator 1 is in a second actuating end position P2. The second air gap 7b refers to the physically same air gap as the first air gap 7a, but having a different height. The second actuating end position P2 means that the actuator is in its extreme, inner position, the position in which the height of the magnet actuator is as small as possible and

where the minimum vibration amplitude is reached during displacement due to electrical current.

The spacer 8 interconnects either the first housing 5 and the second housing 6, the first housing 5 and the magnet 4, or both.

In one embodiment, the spacer 8 is compressible, e.g. in the form of a flexible, resilient gasket 8a, and fixed to an inner surface 5a of the first housing 5, e.g. by means of adhesive. The spacer 8 is in an uncompressed state when the magnet actuator 1 is in the first actuating end position PI, as shown in Fig. 2b. When there is no current in the coil 3, the magnet actuator 1 is in the first actuating end position PI. The spacer 8 is in a compressed state when the magnet actuator 1 is in any position other than the first actuating end position PI, including the second actuating end position P2 shown in Fig. 2c. Such a compressible spacer also functions as suspension for the magnet actuator.

In a further embodiment, the spacer 8 comprises a flexible dust shield 8b connected to the first housing 5 and the second housing 6, preferably the outer peripheral surfaces of the first housing 5 and the second housing 6 such that it covers any circumferential gap present between the first housing 5 and the second housing 6.

In one preferred embodiment, the spacer 8 comprises a flexible gasket 8a as well as a dust shield 8b.

The first housing 5 and the second housing 6 both have an open end 9 and a closed base 10 which is connected by a surrounding wall 11, such that both the first housing 5 and the second housing 6 are cup-shaped.

In one embodiment, the first housing 5 and the second housing 6 have the exact same inner and outer dimensions. As shown in Figs. 4a, 4b, 5, and 6, the cross-section of the first housing 5 and the second housing 6, and hence the magnet actuator 1, may be circular, rectangular, or square.

In a further embodiment, the inner periphery of one of the first housing 5 and the second housing 6 corresponds substantially to the outer periphery of the other of the first housing 5 and the second housing 6, with allowance for movement between the first housing 5 and the second housing 6. The first housing 5 and the second housing 6 may, in such an embodiment, be arranged such that they partially overlap. This is shown in Figs. 7 and 8.

The first housing 5 and the second housing 6 may comprise interconnecting flanges 12 which connect when the magnet actuator 1 is in a first actuating end position PI or a second actuating end position P2 as shown schematically in Fig 8. The flanges of one housing extend inwards, in a direction towards the interior of the housing, while the flanges of the other housing extend outwards, in a direction from the interior of the housing. Furthermore, the surrounding wall 11 of the housing which has an inner periphery which corresponds substantially to the outer periphery of the other housing, i.e. the surrounding wall 11 of the housing having larger inner dimensions, extends past the flanges of the other housing, having smaller inner dimensions, such that the flanges of the housing having smaller inner dimensions are enclosed by the wall 11 and the flanges 12 of the housing having larger inner dimensions. Hence, the flanges overlap such that the first housing 5 and the second housing 6 cannot be separated.

The present disclosure further relates to an electronic device 2, partially shown in Fig. 3, comprising a movable surface 13 such as a display, a device chassis 14, and a magnet actuator 1. The magnet actuator 1 is arranged between the movable surface 13 and the device chassis 14, and adapted to move the movable surface 13 relative to the device chassis 14. Movement of the movable surface 13 generates vibrations within the electronic device 2, such as e.g. sound waves. By this a so called "singing display" is achieved. A back cover is arranged adjacent the side of the device chassis 14 which is the farthest away from the magnet actuator 1.

In one embodiment, the first housing 5 of the magnet actuator 1 is attached to the movable surface 13, and the second housing 6 of the magnet actuator 1 is attached to the device chassis 14. In a further embodiment, the second housing 6 of the magnet actuator 1 is attached to the movable surface 13 and the first housing 5 of the magnet actuator 1 is attached to the device chassis 14.

The present disclosure also relates to a kit for assembling the magnet actuator 1, comprising the magnet actuator 1 and an assembly pin 15. The first housing 5 of the magnet actuator 1 comprises a through-going recess 16a for receiving the assembly pin 15. A first end 15a of the assembly pin 15 is releasably connected to the inner surface 6a of the second housing 6 after having passed through the through-going recess 16a. The first end 15a may be inserted into a recess provided in the inner surface 6a, and releasably connected by means of e.g. threading. A second end 15b of the assembly pin 15 is releasably connected to the outer surface 5b of the first housing 5, such that the first housing 5 and the second housing 6 are interconnected, and the magnet 4 and the coil 3 maintained at a predefined distance from each other by means of the assembly pin 15 during assembly. The components of the magnet actuator may be glued together, during which time the assembly pin 15 maintains all components in their correct locations. Once the components of the magnet actuator have been fixedly interconnected, by means of e.g. adhesive, the assembly pin 15 may be removed by removing it from the inner surface 6a and the outer surface 5b and pulling it out from the through-going recess 16a.

The assembly pin 15 may have any suitable shape. In one embodiment, the assembly pin 15 is T-shaped, and inserted into the magnet actuator 1 such that one leg of the assembly pin 15 extends in the direction of the attractive force F caused by a magnetic field within the magnet actuator 1, when the assembly pin 15 has been received in the through- going recess 16a, and such that the other leg of the assembly pin 15 extends in a plane P perpendicular to the direction of the attractive force F.

In one embodiment, the magnet 4, the spacer 8, or both, also comprise a through-going recess 16b adapted for

accommodating the assembly pin 15 such that the leg of the assembly pin 15 which extends in the direction of the attractive force F at least partially penetrates the magnet 4, the spacer 8, or both. In such a configuration the through-going recess 16 comprises both a through-going recess 16a and through-going recesse 16b.

The various aspects and implementations has been described in conjunction with various embodiments herein. However, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed subject-matter, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.

The reference signs used in the claims shall not be construed as limiting the scope.