SAID OPTICAL SYSTEM

TECHNICAL FIELD

The disclosure relates to an optical system for a camera, the optical system comprising an actuator, an actuation module, an optical module, and a frame at least partially surrounding the optical module.

BACKGROUND

There are several difficulties relating to optical systems for portable electronic devices.

Electronic devices such as mobile phones preferably have as small outer dimensions as possible, while optical systems require certain dimensions in order to provide sufficiently good image sharpness, spatial frequency, sensitivity etc.

Therefore, imaging zooms for portable electronic devices have mostly been digital, which however affects the resolution of the images. Digital zoom does not add any information to image, but is done only by cropping and scaling a portion of original image to larger size. Optical zoom, on the other hand, magnifies the target using lenses and provides more details in the original resolution, providing a better resolution image.

Prior art electronic devices with optical zooms conventionally use pocket camera lens barrels, a solution which not only has large dimensions, but which also seals insufficiently towards the interior of the electronic device, and which is insufficiently rigid, in order to have the resistance expected from an everyday life product, like a portable electronic device, against dust, water, and mechanical impact.

Such a pocket camera solution, if downscaled to the size of a portable electronic device such as a mobile phone, would be expensive to produce. Furthermore, the demand for higher performance cameras with high zoom ratios in portable electronic devices requires even larger sensors and optics, resulting in a product which has even larger dimensions, contradicting the trend of portable electronic devices being as thin as possible. SUMMARY

It is an object to provide an improved optical system. 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 an optical system for a camera, the optical system comprising an actuator, an actuation module, an optical module, and a frame at least partially surrounding the optical module, the actuation module comprising a stationary threaded base element and a moveable dual-threaded connector, the optical module comprising at least one lens and a moveable threaded support element housing the lens, the actuation module and the optical module sharing a center axis, the dual-threaded connector comprising a first connector thread and a second connector thread, the first connector thread and the second connector thread being oriented in opposite directions, the threaded base element comprising a thread engaging the first connector thread, the threaded support element comprising a thread engaging the second connector thread, the actuator being configured to rotate the dual-threaded connector around the center axis in a first tangential direction and in an opposite, second tangential direction,

-the frame interlocking with the threaded support element such that rotation of the threaded support element is prevented, allowing the optical module to be moved between a first end position and a second end position along the center axis in response to rotation of the dual- threaded connector in the tangential directions.

Such a solution utilizes a structure that not only achieves the required focal length for camera optics but does so without visible support while still remaining rigid. The threads transfer external load to the frame without damaging the actuator or possible guides, while also doubling the speed of the zoom action. Furthermore, the setup of threaded parts allows the optical system to be driven by means of a single actuator. Additionally, the height of the optical system is kept to a minimum, e.g. being applicable to electronic devices having a thickness of 7-9 mm.

In a possible implementation form of the first aspect, a height of the optical system along the center axis is larger when the optical module is in the second end position than in the first end position, an overlap between the thread of the threaded base element and the first connector thread, and an overlap between the thread of the threaded support element and the second connector thread, being larger when the optical module is in the first end position than in the second end position, allowing the optical system to fit into a comparatively thin electronic device while still facilitating a focal length which is enough to support high megapixel sensors. Furthermore, the overlap gives sufficient mechanical support to the optical module.

In a further possible implementation form of the first aspect, the frame at least partially surrounds the threaded support element by means of an opening in the frame, a surface of the opening having a shape corresponding to an exterior surface of the threaded support element, the shape being noncircular, providing a simple, efficient, and reliable way of restricting the movement of the threaded support element to the direction of the center axis.

In a further possible implementation form of the first aspect, the first connector thread is a right-handed thread and the second connector thread is a left-handed thread, using well- known combination of threads.

In a further possible implementation form of the first aspect, the threaded base element, the dual-threaded connector, and the threaded support element are at least partially formed as a hollow cylinders, the first connector thread being arranged on an inner surface of the dual- threaded connector cylinder, the second connector thread being arranged on an outer surface of the dual-threaded connector cylinder, and wherein

the thread of the threaded base element is arranged on an outer surface of the threaded base element cylinder, and the thread of the threaded support element is arranged on an inner surface of the threaded support element cylinder, allowing the dual-threaded connector to function as lifting means, as well as supporting means, for the optical module. Furthermore, the outer surface of the optical module is left smooth, facilitating a tight seal against ingress of dust and moisture.

In a further possible implementation form of the first aspect, the optical system further comprises a turning element engaging the actuator and the dual-threaded connector, the actuator being configured to rotate the turning element around the center axis in the first tangential direction and in the second tangential direction, the dual-threaded connector being rotated simultaneously with the turning element, allowing reliable connection between actuator and the remainder of the optical system. In a further possible implementation form of the first aspect, the dual-threaded connector is stationary in relation to the turning element in the first tangential direction and in the second tangential direction, and the dual-threaded connector is movable in relation to the turning element in the direction of the center axis, allowing a single actuator to operate the optical system between end positions.

In a further possible implementation form of the first aspect, the turning element comprises a tongue extending in parallel with the center axis, and the dual-threaded connector comprises a corresponding groove extending in parallel with the center axis, the dual-threaded connector being rotated around the center axis in the first tangential direction and in the second tangential direction by means of the tongue applying a tangentially directed force onto a surface of the groove, the tongue and groove combination allowing contact with the actuator to be maintained while still transferring the rotational movement to the threaded components.

In a further possible implementation form of the first aspect, the actuator is an

electromagnetic actuator, a rotor of the actuator engaging the dual-threaded connector or the turning element such that the dual-threaded connector is rotated around the center axis in the first tangential direction and in the second tangential direction, providing small yet sufficient means for driving the optical system.

In a further possible implementation form of the first aspect, the actuator comprises a lead screw or gear, and the dual-threaded connector or the turning element comprises teeth engaging the lead screw or the gear, providing simple, reliable, and spatially efficient means for driving the optical system.

In a further possible implementation form of the first aspect, the threaded base element houses at least one of a further lens and a sensor, providing a housing for the stationary components of the optical system.

According to a second aspect, there is provided an electronic device comprising an optical system according to the above, a gasket, a device chassis, and a device housing at least partially enclosing the optical system and the device chassis, the device housing comprising a throughgoing opening accommodating the gasket and the optical module of the optical system. The electronic device comprises a structure that not only achieves the required focal length for the camera optics but does so without visible support while still remaining rigid. The visibility of the optical system is kept to a minimum, though allowing a comparatively long part of the optical system to protrude, and the gap between the optical module and the device housing can be efficiently sealed since there are no threads on the outside of optical system.

In a possible implementation form of the second aspect, the device housing comprises the frame of the optical system, reducing the need for additional components and providing very a stable frame and guide for the optical system.

In a further possible implementation form of the second aspect, the device chassis comprises the threaded base element of the optical system, reducing the need for additional components and providing very a stable base element for the optical system.

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 schematic perspective view of an electronic device in accordance with one embodiment of the present invention, wherein the optical system is in a first end position;

Fig. lb is a further schematic illustration of the embodiment of Fig. la, wherein the optical system is in a second end position;

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

Fig. 2b shows a cross-sectional view of the embodiment of Fig. 2a, wherein the optical system is in a first end position; Fig. 2c shows a cross-sectional view of the embodiment of Figs. 2a and 2b, wherein the optical system is in a second end position;

Fig. 3a shows an exploded view of an optical system in accordance with a further

embodiment of the present invention;

Fig. 3b shows a cross-sectional view of the embodiment of Fig. 3a, wherein the optical system is in a first end position;

Fig. 3c shows a cross-sectional view of the embodiment of Figs. 3a and 3b, wherein the optical system is in a second end position.

DETAILED DESCRIPTION

Figs la and lb show an electronic device 17 comprising an optical system 1, a gasket 18, a device chassis 19, and a device housing 20 at least partially enclosing the optical system 1 and the device chassis 19. The device housing 20 comprises a throughgoing opening 21 which accommodates the gasket 18 and the optical module 4 of the optical system 1.

In a first end position PI, shown in Fig. la, the optical system 1 is in a retracted position in which the optical system is retracted past, or aligned with, the outer surface of the device housing 20 such that no part of the optical system 1 protrudes past the outer surface of the device housing 20. In the retracted position, the camera function is preferably inactive, but it is a further possibility that the camera function can be activated independently of the position of the optical system 1. In a second end position P2, shown in Fig. lb, the optical system 1 is in an extended position in which the optical system extends past the outer surface of the device housing 20. In the extended position, the camera function is preferably active, but it is a further possibility that the camera function can be inactivated independently of the position of the optical system 1.

Figs 2a-2c and 3a-3c show different embodiments of the above-mentioned optical system 1. The optical system 1 comprises an actuation module 3, an optical module 4, and a frame 5 at least partially surrounding the optical module 4. The actuation module 3 and the optical module 4 are arranged such that they share a center axis C.

The actuation module 3 comprises a stationary threaded base element 6 and a moveable dual- threaded connector 7. The optical module 4 comprises at least one lens 8 and a moveable threaded support element 9 housing the lens 8. The stationary threaded base element 6 and the moveable threaded support element 9 are interconnected by means of the a moveable dual- threaded connector 7.

The dual-threaded connector 7 comprises a first connector thread 7a and a second connector thread 7b, the first connector thread 7a and the second connector thread 7b being oriented in opposite directions. In one embodiment, the first connector thread 7a is a right-handed thread and the second connector thread 7b is a left-handed thread, it is however possible that the directions of the first connector thread 7a and the second connector thread 7b are inversed, such that the first connector thread 7a is a left-handed thread and the second connector thread 7b is a right-handed thread.

The threaded base element 6 preferably comprises a plate-shaped section and a protruding section extending perpendicular to the surface of the plate-shaped section, from the plate shaped section. The protruding section comprises a thread 6a configured to engage the first connector thread 7a, i.e. if the first connector thread 7a is a right-handed thread, the thread 6a is also right-handed. In one embodiment, the threaded base element 6 furthermore houses at least one of a further lens 15 and a sensor 16, components which ideally are stationary.

The threaded support element 9 comprises a thread 9a configured to engage the second connector thread 7b, i.e. if the second connector thread 7b is a left-handed thread, the thread 9a is also left-handed.

In one embodiment, the threaded base element 6, the dual-threaded connector 7, and the threaded support element 9 are at least partially formed as hollow cylinders, the threaded base element 6 fitting partially within the dual-threaded connector 7, and the dual-threaded connector 7 fitting at least partially, possibly completely, within the threaded support element 9. The first connector thread 7a is arranged on the inner surface of the dual-threaded connector cylinder 7, and the second connector thread 7b is arranged on the outer surface of the dual-threaded connector cylinder 7. The thread 6a of the threaded base element 6 is arranged on the outer surface of the threaded base element cylinder 6, and the thread 9a of the threaded support element 9 is arranged on the inner surface of the threaded support element cylinder 9. Hence, there is an overlap between the threaded base element 6 and the dual- threaded connector 7, as well as an overlap between the threaded support element 9 and the dual-threaded connector 7. The overlap comprises an overlap between the thread 6a of the threaded base element 6 and the first connector thread 7a, and an overlap between the thread 9a of the threaded support element 9 and the second connector thread 7b.

The optical system 1 further comprises an actuator 2, shown in Fig. 3a, which may be an electromagnetic actuator, and/or comprise a lead screw or gear. The actuator 2 is configured to rotate the dual-threaded connector 7 around the center axis C in a first tangential direction D1 and in an opposite, second tangential direction D2. Rotation in the first tangential direction D1 results in the optical system being moved from the first end position PI, i.e. the retracted position, to the second end position P2, i.e. the extended position. Rotation in the second tangential direction D2 results in the optical system being moved from the second end position P2, i.e. the extended position, to the first end position PI, i.e. the retracted position. Depending on the direction of the threads, rotation in the first tangential direction D1 and in the second tangential direction D2 could lead to inversed end positions PI, P2.

The frame 5, shown in Figs. 3a-3c and which at least partially surrounds the optical module 4, interlocks with the threaded support element 9 such that rotation of the threaded support element 9 is prevented. This allows the optical module 4 to be moved between the first end position PI and the second end position P2 along the center axis C in response to rotation of the dual-threaded connector 7 in the tangential directions Dl, D2. In one embodiment, the frame 5 at least partially surrounds the threaded support element 9 and the interlock between the frame 5 and the optical module 4 is achieved by means of an opening 10 in the frame 5. The surface of the opening 10 has a shape which corresponds to the exterior, peripheral surface of the threaded support element 9, the shape being noncircular. As shown in Fig. 3a, the surface of the opening 10 and the peripheral surface of the threaded support element 9 may both be essentially circular, but each being provided with two oppositely arranged flat surfaces. The surface of the opening 10 and the peripheral surface of the threaded support element 9 may also both be essentially elliptical or polygonal. As mentioned above, the first end position PI is a retracted position and the second end position P2 is an extended position. Hence, the height of the optical system 1 along the center axis C is larger when the optical module 4 is in the second end position P2 than in the first end position PI . The overlap between the thread 6a of the threaded base element 6 and the first connector thread 7a, and the overlap between the thread 9a of the threaded support element 9 and the second connector thread 7b, is larger when the optical module 4 is in the first end position PI than in the second end position P2. The overlaps are as small as possible when the optical module 4 is in the second end position P2, such that optical system 1 is as long as possible which provides the suitable focal length to support high megapixel sensors.

In a preferred embodiment, the dual-threaded connector 7 is moved half-way up along its length, which gives support to the optical module 4.

In one embodiment, the optical system 1 further comprises a turning element 11 engaging the actuator 2 and the dual-threaded connector 7. The actuator 2 is configured to rotate the turning element 11 around the center axis C in the first tangential direction D1 and in the second tangential direction D2, the dual-threaded connector 7 being rotated simultaneously with the turning element 11. Preferably, the dual-threaded connector 7 is stationary in relation to the turning element 11 in the first tangential direction D1 and in the second tangential direction D2, while being movable in relation to the turning element 11 in the direction of the center axis.

The turning element 11 may be fixedly connected to the dual-threaded connector 7, e.g. in the form of a flange extending from one end of the dual-threaded connector 7, in a direction perpendicular to the center axis C of the optical system 1. In this case the dual-threaded connector 7 is stationary in relation to the turning element 11 in the first tangential direction Dl, in the second tangential direction D2, and in the direction of the center axis, while being moveable in relation to the threaded base element 6.

Preferably, however, the turning element 11 is a separate component partially enclosing the threaded base element 6. The turning element 11 comprises a disc-shaped section having an opening enclosing one end of the protruding, threaded cylinder section of the threaded base element 6, the disc-shaped section extending parallel with the plate-shaped section of the threaded base element 6 and essentially being in abutment with the plate-shaped section. The turning element 11 comprises at least one, preferably two oppositely arranged, tongues 12 extending in parallel with the center axis C. The dual-threaded connector 7 comprises at least one corresponding groove 13, extending in parallel with the center axis C, adapted for accommodating the tongue 12. The dual-threaded connector 7 is rotated around the center axis C in the first tangential direction D1 and in the second tangential direction D2 by means of the tongue 12 applying a tangentially directed force onto the surface of the groove 13. Simultaneously, the surface of the grove 13 slides along the corresponding surface of the tongue 12 in the direction of the center axis C, allowing the dual-threaded connector 7 to move towards, and from, the threaded base element 6 and the turning element 11 in the direction of the center axis C.

As mentioned above, the actuator 2 may be an electromagnetic actuator, the rotor of which engages the dual-threaded connector 7 or the turning element 11 such that the dual-threaded connector 7 is rotated around the center axis C in the first tangential direction D1 and in the second tangential direction D2, in response to the action of the actuator. The dual-threaded connector 7 or the turning element 11 may comprise grooves, as shown in Fig.2a, preferably arranged along the periphery of the disc-shaped section of the turning element 11 and adapted for engaging the electromagnetic actuator.

In one embodiment, the actuator 2 comprises a lead screw or gear, while the dual-threaded connector 7 or the turning element 11 comprises corresponding teeth 14 engaging the lead screw or the gear, as shown in Fig. 3a. The teeth 14 are preferably arranged along the periphery of the disc-shaped section of the turning element 11. When activated, e.g. by a DC- motor, the turning element 11 turns the dual-threaded connector 7 which is raised by thread 6a. The turning element 11 stays at the bottom to maintain its contact with the DC-motor.

As mentioned above, the present disclosure further relates to an electronic device 17 comprising a gasket 18, a device chassis 19, and a device housing 20 at least partially enclosing the optical system 1 and the device chassis 19. The device housing 20 comprises a throughgoing opening 21 accommodating the gasket 18 and the optical module 4 of the optical system 1, allowing the threaded support element 9 of the optical module 4 to move through the opening 21 as it moves between the first end position PI and the second end position P2 along the center axis C. The optical module 4, the gasket 18, and the opening 21 share center axis C. The optical module 4 can be efficiently sealed against the device housing 20 by means of the gasket 18, since there are no visible threads on the outside of the threaded support element 9, its outer surface being smooth. The gasket 18, e.g. an elastomer sealing ring, is mounted to, or integrated with, the device housing 20. In one embodiment, shown in Figs. 2a-2c, the device housing 20 comprises the frame 5 of the optical system 1 , such that the frame 5 is part of one of the external components of the electronic device, e.g. the back cover.

In one embodiment, the device chassis 19 comprises the threaded base element 6 of the optical system 1. The threaded base element 6 may be integral with the device chassis 19 or a separate component fixed to the device chassis 19 by means of e.g. adhesive or screws.

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.