TECHNICAL FIELD

The disclosure relates to a magnet actuator comprising a first housing arrangement, a second housing arrangement, and a main magnet arranged therebetween.

BACKGROUND

Electronic devices may be provided with magnet actuators in order to generate, e.g., sound waves for audio. 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 of the audio actuator 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 audio 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.

Furthermore, the resonance frequency range of a magnet actuator is usually too limited to be able to produce audio as well as haptic feedback. Audio requires high resonance frequencies, such as 1000 Hz. Haptic feedback, on the other hand, requires resonance frequencies low enough for users to sense them efficiently with their fingers, such as 100-200 Hz. Hence, prior art requires a plurality of magnet actuators to cover a sufficiently broad resonance frequency range.

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 comprising a first housing arrangement comprising a first housing, a first balancing magnet, and a first coil partially surrounding the first balancing magnet, a second housing arrangement comprising a second housing, a second balancing magnet, and a second coil partially surrounding the second balancing magnet, the first coil and the first balancing magnet being at least partially located within, and fixed to, the first housing, the second coil and the second balancing magnet being at least partially located within, and fixed to, the second housing,

a main magnet arranged between the first balancing magnet and the second balancing magnet, a first constant attractive force being generated between the first housing and the main magnet, the first balancing magnet and the main magnet being configured to generate a first constant repulsive force counteracting the first constant attractive force, such that the first housing arrangement and the main magnet are maintained in a force equilibrium state, a second constant attractive force being generated between the second housing and the main magnet, the second balancing magnet and the main magnet being configured to generate a second constant repulsive force counteracting the second constant attractive force, such that the second housing arrangement and the main magnet are maintained in a force equilibrium state, the first coil and the main magnet being configured to generate a first alternating magnetic force, the second coil and the main magnet being configured to generate a second alternating magnetic force, wherein manipulating electrical current in the first coil causes a change in the first alternating magnetic force thereby causing displacement of the first housing arrangement in relation to the main magnet, and/or wherein manipulating electrical current in the second coil causes a change in the second alternating magnetic force thereby causing displacement of the second housing arrangement in relation to the main magnet. 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. Furthermore, the solution facilitates a very compact magnet actuator which, by using one magnet to operate two moving magnets, can not only generate resonance frequencies within a broader range, but also generate resonance frequencies within two different ranges at the same time such as, e.g., audio and haptic feedback. Additionally, the reduced number of elements reduces the complexity of the magnet actuator making it cheaper to manufacture and repair, and leaving fewer dimensional tolerance variations to be considered.

In a possible implementation form of the first aspect, the first alternating magnetic force is an attractive force or a repulsive force, the first alternating magnetic force being changed and the first housing arrangement being displaced a first displacement distance in relation to the main magnet by manipulating the electrical current in the first coil, facilitating a magnet actuator which can generate vibrations within a specific frequency range and in one specific direction.

In a further possible implementation form of the first aspect, the second alternating magnetic force is an attractive force or a repulsive force, the second alternating magnetic force being changed and the second housing arrangement being displaced a second displacement distance in relation to the main magnet by manipulating the electrical current in the second coil, facilitating a magnet actuator which can generate vibrations within a specific frequency range and in a further specific direction.

In a further possible implementation form of the first aspect, the first alternating magnetic force and the second alternating magnetic force are both attractive forces or repulsive forces, facilitating a bidirectional yet spatially efficient magnet actuator.

In a further possible implementation form of the first aspect, the first alternating magnetic force or the second alternating magnetic force is generated and changed independently of the other of the first alternating magnetic force and the second alternating magnetic force, allowing vibrations to be produced in any one desired, or both, directions along the center axis of the magnet actuator. In a further possible implementation form of the first aspect, the first alternating magnetic force and the second alternating magnetic force are generated and changed simultaneously such that the first housing arrangement and the second housing arrangement are both displaced at an identical resonance frequency, facilitating application of a first functionality by means of movement of the housings, such as generating vibrations within the higher resonance frequency interval, producing e.g. sound waves.

In a further possible implementation form of the first aspect, the first alternating magnetic force and the second alternating magnetic force are generated and changed simultaneously, by different magnitudes, such that the first housing arrangement and the second housing arrangement are displaced at different resonance frequencies, allowing a wider interval of resonance frequencies to be generated, such as both sound waves and vibrations for haptic feedback and reducing the space needed for components able generate sound waves and vibrations for haptic feedback.

In a further possible implementation form of the first aspect, displacement by the first displacement distance is executed at a first resonance frequency, displacement by the second displacement distance is executed at a second resonance frequency, the first resonance frequency being at least 3 times higher than the second resonance frequency, facilitating e.g. generation of sound waves and haptic feedback at the same time.

In a further possible implementation form of the first aspect, the magnet actuator further comprises a third housing at least partially enclosing the main magnet, providing secure means for arranging the main magnet in a stationary position as well as amplifying the forces of the magnet.

In a further possible implementation form of the first aspect, the main magnet is fixed to the third housing by means of mechanical locking elements or adhesive, allowing the dimensions of the main magnet to be chosen independently of the inner dimensions of the third housing.

In a further possible implementation form of the first aspect, the magnet actuator further comprises a first flexible printed circuit and a second flexible printed circuit, the first flexible printed circuit being connected to the first coil and arranged between the first coil and an inner surface of the first housing, and the second flexible printed circuit being connected to the second coil and arranged between the second coil and an inner surface of the second housing, facilitating secure and simple connections to a driving component such as a printed circuit board (PCB).

According to a second aspect, there is provided an electronic device comprising a first movable surface, a second moveable surface, an internal component at least partially enclosed by the moveable surfaces, and a magnet actuator according to the above arranged between the first movable surface and the internal component and/or the second moveable surface, the magnet actuator being configured to displace the first movable surface and/or the second moveable surface in response to displacement of the first housing arrangement, and/or in response to displacement of the second housing arrangement, of the magnet actuator, the main magnet of the magnet actuator being fixedly attached to the internal component, either directly or indirectly by means of the third housing of the magnet actuator.

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. Furthermore, a very compact magnet actuator is achieved which, by using one magnet to operate two moving magnets, can not only generate resonance frequencies within a broader range, but also generate resonance frequencies within two different ranges at the same time such as, e.g., audio and haptic feedback.

In a possible implementation form of the second aspect, the first housing of the magnet actuator or the second housing of the magnet actuator is attached to the first movable surface, and the second housing of the magnet actuator or the first housing of the magnet actuator is attached to the second movable surface, and wherein displacement of the first movable surface generates vibrations having a first resonance frequency and/or displacement of the second movable surface generates vibrations having a second resonance frequency within the electronic device, providing support for the components of the magnet actuator as well as facilitating transmission of vibrations both within the higher resonance frequency range, such as audio, as well as the lower resonance frequency range, such as haptic feedback. In a further possible implementation form of the second aspect, the first movable surface is a display and/or the second moveable surface is a device cover, facilitating production of vibrations without needing additional, separate components.

In a further possible implementation form of the second aspect, the internal component is one of a device chassis, a printed circuit board, and a device frame, facilitating production of vibrations without needing additional, separate components as well as a very stable magnet actuator which can withstand large external forces.

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. la shows a perspective view of an electronic device in accordance with one embodiment of the present invention;

Fig. lb shows a partial cross-section of the electronic device shown in Fig. la;

Fig. 2 shows an exploded view of a magnet actuator in accordance with one embodiment of the present invention;

Fig. 3a shows a perspective view of the magnet actuator shown in Fig. 2;

Fig. 3b shows a cross-section of the magnet actuator shown in Figs. 2 and 3a;

Figs. 4a and 4b show cross-sections of an electronic device in accordance with one embodiment of the present invention. DETAILED DESCRIPTION

Figs la- lb and 4a-4b show an electronic device 7 comprising a first movable surface 8, such as a display, a second moveable surface 9, such as a device cover, an internal component 10, such as a device chassis, a printed circuit board, and/or a device frame, and a magnet actuator 1. The magnet actuator 1 is arranged between the first movable surface 8 and the internal component 10 and/or the second moveable surface 9, and is configured to displace the first movable surface 8 and/or the second moveable surface 9 in response to displacement of a first housing arrangement 2 and/or a second housing arrangement 3 of the magnet actuator 1.

As shown in Fig. 2, the magnet actuator 1 comprises a first housing arrangement 2, a second housing arrangement 3, and a main magnet 4. The first housing arrangement 2 comprises a first housing 2a, a first balancing magnet 2b, and a first coil 2c partially surrounding the first balancing magnet 2b. The first coil 2c and the first balancing magnet 2b are at least partially located within, and fixed to, the first housing 2a. Correspondingly, the second housing arrangement 3 comprises a second housing 3a, a second balancing magnet 3b, and a second coil 3c partially surrounding the second balancing magnet 3b. The second coil 3c and the second balancing magnet 3b are at least partially located within, and fixed to, the second housing 3a. The first coil 2c and the second coil 3c may be planar voice coils, and connected to audio amplifiers.

The first housing 2a and the second housing 3 a are made of magnetic material, such as iron. Furthermore, the housings 2a, 3 a may both be shaped as a hollow cylinder having one closed end and one open end, i.e. the cross-section of each housing 2a, 3a, along its center axis, which corresponds to the center axis of the magnet actuator 1, is essentially U-shaped. The peripheral surface of each housing 2a, 3a could have circular or elliptical shape, or e.g. be a polygon.

The open end of the first housing 2a and the open end of the second housing 3 a are arranged such that they face each other, allowing the magnet to be at least partially enclosed by the first housing 2a and the second housing 3 a. This allows the first housing 2a and the second housing 3a to limit any magnetic forces generated by the magnet actuator 1 to an enclosed space within at least one of the first housing 2a and the second housing 3 a. The main magnet 4 is arranged between the first balancing magnet 2b and the second balancing magnet 3b. In one embodiment, shown in Figs. 3a-3b the main magnet 4 is at least partially enclosed by a third housing 5, which third housing 5 is made of magnetic material, such as iron , and which may be shaped as a hollow cylinder having two opposite open ends. The third housing 5 is attached to the above-mentioned internal component 10 by means of the third housing 5 and, e.g., screws or adhesive. The main magnet 4 may be fixed to the third housing 5 directly, by adhesive or press-fit, or by means of mechanical locking elements 6. In a further embodiment, the main magnet is fixed directly to the internal component 10, e.g., by means of adhesive.

In one embodiment, the magnet actuator 1 comprises a first flexible printed circuit 2d and a second flexible printed circuit 3d, the circuits to be connected to drive means such as a printed circuit board (PCB). The first flexible printed circuit 2d is connected to the first coil 2c and arranged between the first coil 2c and an inner surface of the first housing 2a, and the second flexible printed circuit 3d is connected to the second coil 3c and arranged between the second coil 3 c and an inner surface of the second housing 3 a. The magnet actuator 1 may comprises wires instead of the first flexible printed circuit 2d and the second flexible printed circuit 3d.

A first constant attractive force Fcl is generated between the first housing 2a and the main magnet 4. The first balancing magnet 2b and the main magnet 4 are configured to generate a first constant repulsive force Fc2 counteracting the first constant attractive force Fcl, such that the first housing arrangement 2 and the main magnet 4 are maintained in a force equilibrium state. Correspondingly, a second constant attractive force Fc3 is generated between the second housing 3a and the main magnet 4. The second balancing magnet 3b and the main magnet 4 are configured to generate a second constant repulsive force Fc4 counteracting the second constant attractive force Fc3, such that the second housing arrangement 3 and the main magnet 4 are maintained in a force equilibrium state.

Additionally, the first coil 2c and the main magnet 4 are configured to generate a first alternating magnetic force F _A I , and the second coil 3c and the main magnet 4 are configured to generate a second alternating magnetic force F _A 2. By manipulating the electrical current in the first coil 2c a change in the first alternating magnetic force F _A I is caused, which in turn causes displacement of the first housing arrangement 2 in relation to the main magnet 4. By manipulating the electrical current in the second coil 3c a change in the second alternating magnetic force F _A 2 is caused, which in turn causes displacement of the second housing arrangement 3 in relation to the main magnet 4.

The first alternating magnetic force F _A I is an attractive force or a repulsive force. The first alternating magnetic force F _A I is changed and the first housing arrangement 2 is displaced a first displacement distance dl in relation to the main magnet 4 by manipulating the electrical current in the first coil 2c. Correspondingly, the second alternating magnetic force F _A 2 is an attractive force or a repulsive force. The second alternating magnetic force F _A 2 is changed and the second housing arrangement 3 is displaced a second displacement distance d2 in relation to the main magnet 4 by manipulating the electrical current in the second coil 3c.

In one embodiment, only one of the first alternating magnetic force F _A I and the second alternating magnetic force F _A 2 is generated and/or changed. The first alternating magnetic force F _A I or the second alternating magnetic force F _A 2 is either an attractive force or a repulsive force. The first housing arrangement 2 may be displaced a first displacement distance dl in relation to the main magnet 4 by manipulating the electrical current in the first coil 2c. Optionally, the second housing arrangement 3 is displaced a first displacement distance dl in relation to the main magnet by manipulating the electrical current in the second coil 3c.

In one embodiment, the first alternating magnetic force F _A I and the second alternating magnetic force F _A 2 are both attractive forces or repulsive forces. The first alternating magnetic force F _A I or the second alternating magnetic force F _A 2 may be generated and changed independently of the other of the first alternating magnetic force F _A I and the second alternating magnetic force F _A 2.

In a further embodiment, the first alternating magnetic force F _A I and the second alternating magnetic force F _A 2 are generated and changed simultaneously such that the first housing arrangement 2 and the second housing arrangement 3 are both displaced at an identical resonance frequency. This allows the height of the magnet actuator 1 to vary in accordance with the drive signal, while the main magnet 4 is maintained in its stationary position between the first balancing magnet 2b and the second balancing magnet 3b. In one embodiment, displacement by the first displacement distance dl is executed at a first resonance frequency, within a first resonance frequency interval, while displacement by the second displacement distance d2 is executed at a second resonance frequency, within a second resonance frequency interval. The first resonance frequency is at least 3 times higher than the second resonance frequency, e.g. the first resonance frequency may be ca 1000 Hz while the second resonance frequency is ca 100 Hz. The first resonance frequency interval is generally suitable for producing vibrations in the form of sound waves, and the second resonance frequency interval is suitable for producing vibrations in the form of haptic feedback to the user. The second resonance frequency interval may also be suitable for use as a subwoofer, expanding the audio band to frequencies too low to be comprised within the first resonance frequency interval.

Displacement by the first displacement distance dl at a first resonance frequency, and displacement by the second displacement distance d2 at a second resonance frequency may be executed simultaneously, i.e. sound waves and haptic feedback may be generated

simultaneously or individually. In one embodiment, privacy leakage is minimized by allowing sound waves to be produced by means of vibrations at first resonance frequency, in one direction, while the vibration coupling in the opposite direction, e.g. to the back cover of an electronic device comprising the magnet actuator 1 , is minimized by simultaneously allowing vibrations at second resonance frequency.

The present disclosure further relates to an electronic device, mentioned above. The electronic device 7 comprises a first movable surface 8, a second moveable surface 9, an internal component 10 at least partially enclosed by the moveable surfaces 8, 9, and a magnet actuator 1 arranged between the first movable surface 8 and the internal component 10 and/or the second moveable surface 9.

The magnet actuator 1 is configured to displace the first movable surface 8 and/or the second moveable surface 9 in response to displacement of the first housing arrangement 2, and/or in response to displacement of the second housing arrangement 3, of the magnet actuator 1. The main magnet 4 of the magnet actuator 1 is fixedly attached to the internal component 10, either directly or indirectly by means of the third housing 5 of the magnet actuator 1. In one embodiment the first housing 2a of the magnet actuator 1 or the second housing 3a of the magnet actuator 1 is attached to the first movable surface 8, and the second housing 3a of the magnet actuator 1 or the first housing 2a of the magnet actuator 1 is attached to the second movable surface 9, preferably by means of adhesive. Displacement of the first movable surface 8 generates vibrations having a first resonance frequency and/or displacement of the second movable surface 9 generates vibrations having a second resonance frequency within the electronic device 7. Due to the stiffness of the moveable surfaces 8, 9, the system comprising the moveable surfaces 8, 9, the internal component 10, and the magnet actuator 1 has high spring-mass resonance facilitating high resonance frequencies.

Displacement of the movable surfaces 8,9, by means of the magnet actuator 1, generates vibrations having a first and/or a second resonance frequency within the electronic device 5. The moveable surfaces 8,9 may be displaced such that they bend in a direction from or towards the internal component 10.

The various aspects and implementations have 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.