Electromagnetic assembly generating three-dimensional movement of an optical module

Abstract

An electromagnetic assembly (1) configured to generate three-dimensional movement of at least one optical module (2), said electromagnetic assembly (1) comprising at least one magnet (6), at least one first electromagnetic coil (3) forming a first actuator (11) together with said magnet (6), and at least one second electromagnetic coil (5) forming a second actuator (12) together with said magnet (6). One of said first electromagnetic coil (3) and said second electromagnetic coil (5) surrounds said magnet (6), and the other of said first electromagnetic coil (3) and said second electromagnetic coil (5) extends adjacent said magnet (6). Manipulation of electrical current in said first actuator (11) generates movement of said optical module (2) in a main plane (P), and manipulation of electrical current in said second actuator (12) generates movement of said optical module (2) in directions along a normal (N) to said main plane (P).

Description

[0001] ELECTROMAGNETIC ASSEMBLY GENERATING THREE-DIMENSIONAL MOVEMENT OF AN OPTICAL MODULE

[0002] TECHNICAL FIELD

[0003] The disclosure relates to an electromagnetic assembly configured to generate three-dimensional movement of at least one optical module, the electromagnetic assembly comprising at least one magnet, at least one first electromagnetic coil, and at least one second electromagnetic coil. The disclosure also relates to an optical system comprising at least one optical module and at least one electromagnetic assembly, as well as an electronic apparatus comprising an optical system.

[0004] BACKGROUND

[0005] For the past 15 years, miniature voice coil motors (VCM) have been used for auto-focus (AF) and optical image stabilization (OIS) in cameras, usually using a specific electromagnetic actuation principle for generating linear displacement referred to as the sweeping coil (or sweeping magnet) method.

[0006] A static coil array of the OIS section of the VCM usually lies underneath the lens system. The magnets are located in the upper moving part of the optical unit that contains the lenses. Such a system is called “lens shift OIS”. Lens shift type OIS system comprise relatively small sized coils that need to manage moving a massive upper part containing the magnets, lenses, and the AF system.

[0007] A key issue with conventinal sweeping coil setups is that, although they are simple to manufacture, assemble, and integrate, their efficiency remains relatively low. Since the efficiency is low, power consumption is high when attempting to generate adequate force for moving the upper parts of the camera. The size of different system parts, such as coils or magnets, can be increased in order to increase the force generation, however, this requires more volumetric space and also increases the weight of the upper part of the camera.

[0008] The severity of this problem escalates as larger image sensors are being used together with large and heavy lenses as well as a variable aperture unit for adjusting incoming light.

[0009] Hence, there is a need for an improved electromagnetic assembly suitable for the optical system of an electronic apparatus such as a smartphone.

[0010] SUMMARY

[0011] It is an object to provide an improved electromagnetic assembly for an electronic apparatus. 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.

[0012] According to a first aspect, there is provided an electromagnetic assembly configured to generate three-dimensional movement of at least one optical module, the electromagnetic assembly comprising at least one magnet, at least one first electromagnetic coil, the first electromagnetic coil forming a first actuator together with the magnet, and at least one second electromagnetic coil, the second electromagnetic coil forming a second actuator together with the magnet, one of the first electromagnetic coil and the second electromagnetic coil surrounding the magnet, the other of the first electromagnetic coil and the second electromagnetic coil extendi ng adj acent the magnet, manipulation of electrical current in the first actuator generating movement of the optical module in a main plane, and manipulation of electrical current in the second actuator generating movement of the optical module in directions along a normal to the main plane.

[0013] This solution facilitates an electromagnetic assembly which utilizes a sweeping coil / magnet arrangement, where the coild an magnet are arranged in parallel, together with a through coil system, i.e. an arrangement where the coil encoses the magnet. This allows using VCM technology which provides the best technical maturity, supplier availability, mass-production capability, price, and technology experience, while at the same time improving the efficiency of the VCM solution significantly.

[0014] In a possible implementation form of the first aspect, in the first actuator, the first electromagnetic coil extends in a first plane adjacent the magnet and, in the second actuator, the second electromagnetic coil surrounds the magnet in a second plane, the second plane being parallel with the first plane, or, in the second actuator, the second electromagnetic coil extends in the main plane adjacent the magnet and, in the first actuator, the first electromagnetic coil surrounds the magnet in a third plane, the third plane being perpendicular to the main plane. This arrangement facilitates sweeping coil and through coil arrangements to be created, and operated, by sharing some components. This reduces costs as well as the volume required for the electromagnetic assembly.

[0015] In a further possible implementation form of the first aspect, the electromagnetic assembly comprises four magnets, four first electromagnetic coils, and one second electromagnetic coil. This reduces the weight of the electromagnetic assembly.

[0016] In a further possible implementation form of the first aspect, the electromagnetic assembly comprises four magnets, four first electromagnetic coils, and four second electromagnetic coils. This reduces the volume required for the electromagnetic assembly.

[0017] In a further possible implementation form of the first aspect, the first electromagnetic coil is configured to be fixed to a stationary base of the optical module, the second electromagnetic coil is configured to be fixed to a movable lens unit of the optical module, and the magnet is configured to be fixed to a movable lens unit carrier of the optical module, facilitating the required actuation as well as interconnection that does not require separate components.

[0018] In a further possible implementation form of the first aspect, the manipulation of electrical current in the first actuator and the manipulation of electrical current in the second actuator takes place at least partially simultaneously, asslowing autofocus and optical image stabilization to be active at the same time.

[0019] In a further possible implementation form of the first aspect, movement of the optical module in the main plane is generated by means of the second electromagnetic coil and the magnet moving, in the second plane, relative the first electromagnetic coil. This requires the smallest possible volume for the operation of the electromagnetic assembly.

[0020] In a further possible implementation form of the first aspect, movement of the optical module in the main plane is generated by means of the second electromagnetic coil assembly and the magnet moving, in the main plane, relative the first electromagnetic coil. This reduces the complexity and weight of the electromagnetic assembly.

[0021] In a further possible implementation form of the first aspect, movement of the optical module along the normal is generated by means of the second electromagnetic coil moving relative the magnet. This facilitates a simple and compact structure for autofocus. In a further possible implementation form of the first aspect, the electromagnetic actuator further comprises first resilient connection elements configured to connect the movable lens unit to the movable lens unit carrier, and / or second resilient connection elements configured to connect the movable lens unit carrier to the stationary base, the first resilient connection elements and the second resilient connection elements being configured to generate a return force on the optical module when there is no electrical current in the first actuator or the second actuator. The resilient connection elements also provide guidance and support to the movable lens unit and the movable lens unit carrier.

[0022] In a further possible implementation form of the first aspect, the first resilient connection element and / or the second resilient connection element is a metal flexure or a wire spring. This provides stability as well as flexibility.

[0023] According to a second aspect, there is provided an optical system comprising at least one optical module and at least one electromagnetic assembly as described above, the electromagnetic assembly being configured to generate linear movement of the optical module(s) along a displacement axis extending coaxially with, or transverse to, an optical axis of the optical module(s). This allows a optical system wich is reliable and relatively inexpensive yet still efficient and with high capability. The performance of the optical system can be improved in particular for large size size cameras using large and heavy optics (8 or more elements, glass lenses, variable aperture) in AF operation (by providing a fast and sharp autofocus system, no pumping under external shaking) as well as OIS operation (by providing large angle correction OIS and high frequency performance, e.g. during running, inside car, on bicycle / motorcycle, on roller coasters etc.).

[0024] In a possible implementation form of the second aspect, one electromagnetic assembly is arranged at each side of the optical module, ensuring the optical module is held and moved evenly, i.e. without tilt, at all times.

[0025] In a further possible implementation form of the second aspect, the optical module comprises at least one lens or a sensor, allowing the electromagnetic assembly to be used wherever suitable within the optical system.

[0026] According to a third aspect, there is provided an electronic apparatus comprising the optical system according to the above. Such an electronic apparatus is provided with an optical system wich is reliable and relatively inexpensive yet still efficient and with high capability.

[0027] These and other aspects will be apparent from the embodiments described below.

[0028] BRIEF DESCRIPTION OF THE DRAWINGS

[0029] 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:

[0030] Fig. 1 shows a schematic cross-sectional view of an electronic apparatus comprising an electromagnetic assembly in accordance with an example of the embodiments of the disclosure;

[0031] Fig. 2 shows a perspective view of the electromagnetic assembly of Fig. 1;

[0032] Fig. 3 shows a schematic cross-sectional view of an electromagnetic assembly in accordance with a further example of the embodiments of the disclosure;

[0033] Fig. 4 shows a perspective view of the electromagnetic assembly of Fig. 3;

[0034] Fig. 5 shows a schematic top view of the electromagnetic assembly of Figs. 1 and 2;

[0035] Fig. 6 shows a schematic top view of the electromagnetic assembly of Figs. 3 and 4.

[0036] DETAILED DESCRIPTION

[0037] The present invention relates to an electromagnetic assembly 1 configured to generate three-dimensional movement of at least one optical module 2, the electromagnetic assembly 1 comprising at least one magnet 6, at least one first electromagnetic coil 3, the first electromagnetic coil 3 forming a first actuator 11 together with the magnet 6, and at least one second electromagnetic coil 5, the second electromagnetic coil 5 forming a second actuator 12 together with the magnet 6, one of the first electromagnetic coil 3 and the second electromagnetic coil 5 surrounding the magnet 6, the other of the first electromagnetic coil 3 and the second electromagnetic coil 5 extending adjacent the magnet 6, manipulation of electrical current in the first actuator 11 generating movement of the optical module 2 in a main plane P, and manipulation of electrical current in the second actuator 12 generating movement of the optical module 2 in directions along a normal N to the main plane P.

[0038] Embodiments of the electromagnetic assembly 1 are illustrated in Figs. 5 and 6. The electromagnetic assembly 1 is configured to generate three-dimensional movement of at least one optical module 2. The optical module 2 may comprise one or several lenses, or an image sensor.

[0039] The electromagnetic assembly 1 comprises at least one magnet 6, at least one first electromagnetic coil 3, and at least one second electromagnetic coil 5. The first electromagnetic coil 3 forms a first actuator 11 together with the magnet 6 and the second electromagnetic coil 5 forms a second actuator 12 together with the magnet 6. In other words, the same magnet 6 is part of both the fist actuator 11 and the second actuator 12.

[0040] One of the first electromagnetic coil 3 and the second electromagnetic coil 5 surrounds the magnet 6, while the other of the first electromagnetic coil 3 and the second electromagnetic coil 5 extends adjacent the magnet 6. Figs. 1, 2, and 5 shows embodiments where the first electromagnetic coil 3 extends adjacent the magnet 6, i.e. in parallel with the magnet and the second electromagnetic coil 5. The second electromagnetic coil 5 surrounds the magnet 6. Figs. 3, 4, and 6 shows shows embodiments where the second electromagnetic coil 5 extends adjacent the magnet 6, i.e. perpendicular to the magnet and the second electromagnetic coil 5. The first electromagnetic coil 3 surrounds the magnet 6.

[0041] When a coil surrounds a magnet such that the magnet moves within the space enclosed by the coil, they form a through coil system wherein the electric field from the coil and magnetic flux from the magnet have better interaction than in a sweeping coil system, where the magnet moves along one side of the coil. This facilitates either a reduction of magnet size or increased force generation.

[0042] As illustrated in Figs. 1 and 3, manipulation of electrical current in the first actuator 11 generates movement of the optical module 2 in a main plane P, i.e. in a plane defined by what is usually referred to as x- and y-axes. Manipulation of electrical current in the second actuator 12 generates movement of the optical module 2 in directions along a normal N to the main plane P, i.e. in what is usually referred to as the z-axis. Movement within plane P is conventionally used for optical image stabilization, while movement along normal N is used for autofocus.

[0043] The manipulation of electrical current in the first actuator 11 and the manipulation of electrical current in the second actuator 12 takes place at least partially simultaneously.

[0044] As illustrated in Figs. 1 and 2, the first electromagnetic coil 3 may extend in a first plane Pl adjacent the magnet 6, such that the first electromagnetic coil 3 and the magnet 6 extend substantially in parallel. The magnet 6 and the first electromagnetic coil 3 together form the first actuator 11. The second electromagnetic coil 5 surrounds the magnet 6 in a second plane P2, the second plane P2 being parallel with the first plane Pl. The magnet 6 and the second electromagnetic coil 5 together form the second actuator 12. Movement of the optical module 2 in the main plane P is generated by means of the second electromagnetic coil 5 and the magnet 6 moving, in the second plane P2, relative the first electromagnetic coil 3. As shown in Fig. 5, the electromagnetic assembly 1 may comprise four magnets 6, four first electromagnetic coils 3, and four second electromagnetic coils 5.

[0045] Alternatively, as illustrated in Figs. 3 and 4, the first electromagnetic coil 3 may surround the magnet 6 in a third plane P3, the third plane P3 being perpendicular to the main plane P and parallel with normal N. The magnet 6 and the first electromagnetic coil 3 together form the first actuator 11. The second electromagnetic coil 5 extends in the main plane P adjacent the magnet 6, such that the second electromagnetic coil 5 extends substantially perpendicular to the magnet 6. The magnet 6 and the second electromagnetic coil 5 together form the second actuator 12. Movement of the optical module 2 in the main plane P is generated by means of the second electromagnetic coil assembly 5 and the magnet 6 moving, in the main plane P, relative the first electromagnetic coil 3. As shown in Fig. 6, the electromagnetic assembly 1 may comprise four magnets 6, four first electromagnetic coils 3, and one second electromagnetic coil 5.

[0046] The movement of the optical module 2 along the normal N is generated by means of the second electromagnetic coil 5 moving relative the magnet 6.

[0047] As illustrated in Figs. 5 and 6, the first electromagnetic coil 3 may be configured to be fixed to a stationary base 13 of the optical module 2. The second electromagnetic coil 5 may be configured to be fixed to a movable lens unit 14 of the optical module 2. The magnet 6 may be configured to be fixed to a movable lens unit carrier 15 of the optical module 2.

[0048] Figs. 5 and 6 also illustrate optional first resilient connection elements 7 configured to connect the movable lens unit 14 to the movable lens unit carrier 15, and optional second resilient connection elements 8 configured to connect the movable lens unit carrier 15 to the stationary base 13. The first resilient connection elements 7 and the second resilient connection elements 8 are configured to generate a return force on the optical module 2 when there is no electrical current in the first actuator 11 or the second actuator 12. The first resilient connection elements 7 and the second resilient connection elements 8 also provide guidance and support for the movable lens unit 14 and the movable lens unit carrier 15, i.e. for autofocus and optical image stabilization.

[0049] The first resilient connection element 7 and / or the second resilient connection element 8 may be a metal flexure or a wire spring.

[0050] The present invention also relates to an optical system 9 comprising at least one optical module 2 and at least one electromagnetic assembly 1 according to the above. The electromagnetic assembly 1 is configured to generate linear movement of the optical module(s) 2 along a displacement axis Al, A2 extending coaxially with, or transverse to, an optical axis A3 of the optical modules 2.

[0051] As shown in Figs. 5 and 6, one electromagnetic assembly 1 may be arranged at each side of the optical module 2. In particular, the optical system 9 may comprise four electromagnetic assemblies 1. As shown in Fig. 6, the second electromagnetic coil 5 may be shared by all electromagnetic assemblies 1.

[0052] Furthermore, the present invention relates to an electronic apparatus 10, such as a smartphone or tablet, comprising the optical system 9 described above.

[0053] 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 measures cannot be used to advantage.

[0054] The reference signs used in the claims shall not be construed as limiting the scope. Unless otherwise indicated, the drawings are intended to be read (e.g., cross-hatching, arrangement of parts, proportion, degree, etc.) together with the specification, and are to be considered a portion of the entire written description of this disclosure. As used in the description, the terms “horizontal”, “vertical”, “left”, “right”, “up” and “down”, as well as adjectival and adverbial derivatives thereof (e.g., “horizontally”, “rightwardly”, “upwardly”, etc.), simply refer to the orientation of the illustrated structure as the particular drawing figure faces the reader. Similarly, the terms “inwardly” and “outwardly” generally refer to the orientation of a surface relative to its axis of elongation, or axis of rotation, as appropriate.

Claims

CLAIMS1. An electromagnetic assembly (1) configured to generate three-dimensional movement of at least one optical module (2), said electromagnetic assembly (1) comprising:- at least one magnet (6),- at least one first electromagnetic coil (3), said first electromagnetic coil (3) forming a first actuator (11) together with said magnet (6); and-at least one second electromagnetic coil (5), said second electromagnetic coil (5) forming a second actuator (12) together with said magnet (6); one of said first electromagnetic coil (3) and said second electromagnetic coil (5) surrounding said magnet (6), the other of said first electromagnetic coil (3) and said second electromagnetic coil (5) extending adjacent said magnet (6), manipulation of electrical current in said first actuator (11) generating movement of said optical module (2) in a main plane (P), and manipulation of electrical current in said second actuator (12) generating movement of said optical module (2) in directions along a normal (N) to said main plane (P).

2. The electromagnetic assembly (1) according to claim 1, wherein, in said first actuator (11), said first electromagnetic coil (3) extends in a first plane (Pl) adjacent said magnet (6) and, in said second actuator (12), said second electromagnetic coil (5) surrounds said magnet (6) in a second plane (P2), said second plane (P2) being parallel with said first plane (Pl), or wherein, in said second actuator (12), said second electromagnetic coil (5) extends in said main plane (P) adjacent said magnet (6) and, in said first actuator (11), said first electromagnetic coil (3) surrounds said magnet (6) in a third plane (P3), said third plane (P3) being perpendicular to said main plane (P).

3. The electromagnetic assembly (1) according to claim 1 or 2, wherein said first electromagnetic coil (3) is configured to be fixed to a stationary base (13) of said optical module (2), said second electromagnetic coil (5) is configured to be fixed to a movable lens unit (14) of said optical module (2), and said magnet (6) is configured to be fixed to a movable lens unit carrier (15) of said optical module (2).

4. The electromagnetic actuator (1) according to any one of the previous claims, wherein said manipulation of electrical current in said first actuator (11) and said manipulation of electrical current in said second actuator (12) takes place at least partially simultaneously.

5. The electromagnetic actuator (1) according to any one of the previous claims, wherein movement of said optical module (2) in said main plane (P) is generated by means of said second electromagnetic coil (5) and said magnet (6) moving, in said second plane (P2), relative said first electromagnetic coil (3).

6. The electromagnetic actuator (1) according to any one of claims 1 to 4, wherein movement of said optical module (2) in said main plane (P) is generated by means of said second electromagnetic coil assembly (5) and said magnet (6) moving, in said main plane (P), relative said first electromagnetic coil (3).

7. The electromagnetic actuator (1) according to any one of the previous claims, wherein movement of said optical module (2) along said normal (N) is generated by means of said second electromagnetic coil (5) moving relative said magnet (6).

8. The electromagnetic actuator (1) according to any one of the previous claims, further comprising first resilient connection elements (7) configured to connect said movable lens unit (14) to said movable lens unit carrier (15), and / or second resilient connection elements (8) configured to connect said movable lens unit carrier (15) to said stationary base (13), said first resilient connection elements (7) and said second resilient connection elements (8) being configured to generate a return force on said optical module (2) when there is no electrical current in said first actuator (11) or said second actuator (12).

9. The electromagnetic actuator (1) according to claim 8, wherein said first resilient connection element (7) and / or said second resilient connection element (8) is a metal flexure or a wire spring.

10. An optical system (9) comprising at least one optical module (2) and at least one electromagnetic assembly (1) according to any one of claims 1 to 9, said electromagnetic assembly (1) being configured to generate linear movement of said optical module(s) (2) along a displacement axis (Al, A2) extending coaxially with, or transverse to, an optical axis (A3) of said optical module(s) (2).

11. The optical system (9) according to claim 10, wherein one electromagnetic assembly (1) is arranged at each side of said optical module (2).

12. The optical system (9) according to claim 10 or 11, wherein said optical module (2) comprises at least one lens or a sensor.

13. An electronic apparatus (10) comprising the optical system (9) according to any one of claims 10-12.

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