Imaging apparatus

The imaging apparatus comprises a retractable structure with active and inactive positions. In the inactive position the lens group resides in proximity to an image sensor, and in the active position the lens group resides at a predetermined distance from the image sensor. The lens group is moved between active and inactive positions by at least one actuator. The imaging apparatus also includes a field flattening lens with a concave shape on the side opposite to the image sensor and facing the moving lens group.

BACKGROUND

Digital cameras usually comprise a lens and a sensor for capturing an image by capturing light and converting it into electrical signals. Mobile electronic devices such as smart phones are usually equipped with an imaging apparatus, for example, a camera. The imaging quality of the mobile electronic devices may be improved by optical image stabilization or autofocus. A current trend in designing mobile electronic devices aims for thin devices, wherein the form factor benefits from thin imaging apparatus to be housed inside the mobile electronic device.

SUMMARY

The imaging apparatus comprises a retractable structure with active and inactive positions. An outermost lens group and a lens group actuator are movable along an optical axis. Examples of a lens group actuator are an autofocus actuator or an optical image stabilizer. In the inactive position the lens group and the lens group actuator reside close to an image sensor.

In the active position the outermost lens group and the lens group actuator are further from the image sensor along the optical axis. The retractable structure may protrude from the device housing the imaging apparatus. In one example the outermost lens group and the lens group actuator protrude from the device. In one example the structure is reversed, the image sensor protrudes from the device while the outermost lens group is fixed to the device body.

The device comprises a field flattening lens fixed to the image sensor, compensating for possible tilt of the outermost lens group. The structure allows imaging apparatuses with better optical characteristics to be implemented for example in very thin devices. Devices with various form factors may benefit from smaller imaging apparatus as there is more room to implement other features to the device.

Many of the attendant features will be more readily appreciated as they become better understood by reference to the following detailed description considered in connection with the accompanying drawings. The embodiments described below are not limited to implementations which solve any or all of the disadvantages of known imaging apparatuses integrated in hand-held devices.

DETAILED DESCRIPTION

The detailed description provided below in connection with the appended drawings is intended as a description of the present embodiments and is not intended to represent the only forms in which the present embodiments may be constructed or utilized. However, the same or equivalent functions and sequences may be accomplished by different embodiments.

Although the present embodiments are described and illustrated herein as being implemented in a smartphone, the device described is provided as an example and not a limitation. As those skilled in the art will appreciate, the present embodiments are suitable for application in a variety of different types of mobile and/or hand-held apparatuses, e.g. in tablets, laptops, digital cameras or gaming consoles.

FIG. 1ashows a front side of one example of an electronic device incorporating an imaging apparatus, wherein one embodiment of the electronic device is a smartphone. The electronic device comprises a body100comprising a display110, a speaker120, a microphone130and keys140. The electronic device comprises an imaging apparatus150, a camera on one surface. The electronic device may comprise two or more cameras, for example a front camera150on the front surface and another imaging apparatus, a rear camera160on the rear side.FIG. 1bshows the rear side of the electronic device, wherein the rear camera160resides on a retractable element161. In one example the retractable element provides a protective casing for at least one lens actuator and a first lens group. The retractable element161is shown in an active position, wherein at least one lens and at least one actuator are moved apart from the image sensor group along an optical axis. The optical axis is a line along which there is some degree of rotational symmetry in an optical system. The optical axis is an imaginary line that defines a path along which light propagates through the system. In an inactive position the retractable element161may be flush with the rear surface. According to an embodiment, a transparent front surface101made of glass covers the display and the lens of the front camera150. The rear surface102is opaque and is, for example, made of plastic or metal. Having a retractable element protruding from a glass surface may require additional edges and sharp corners to be manufactured to the glass surface, therefore implementing the retractable element on a surface made of plastic or metal may be more economical.

FIGS. 2aand 2billustrate a device200having a movable sensor group inside the retractable element210, according to an embodiment. The retractable element210protrudes from the rear surface220. The front surface230is covered with transparent material such as glass. An imaging device240, for example a camera, has an optical field of vision241through the flush front surface230. The retractable element210protrudes from the rear surface220in the active position, providing additional distance between the sensor group and the first lens group. In an embodiment a portion of the transparent front surface230is comprised in the first lens group. As illustrated in the previous examples, the travel of the retractable element may be few millimeters to allow the active position.

FIG. 3ais a simplified cross-sectional view of the imaging apparatus implemented in the electronic device in the active position. A first lens group320is positioned on the optical axis301, wherein the first lens group320comprises the lens through which the light travels to the image sensor group350. The first lens group320may comprise only one lens or it may be a combination of several lenses. In an embodiment, a window330on the retractable element311is a lens forming a part of the first lens group320. The window330is not moved by a lens group actuator. In an embodiment, the first lens group320is a lens barrel, wherein the lenses may be fixed in relation to each other or they may be moved in order to enable various optical characteristics. An autofocus actuator340is configured to move the first lens group320or at least one lens in the first lens group320in order to reach a sharp focus on the image plane and on the image sensor350. In an embodiment, the autofocus actuator is configured to alter the optical zoom factor. In an embodiment, the optical zoom factor is altered by an actuator configured inside the lens barrel. The autofocus actuator340is an example of a lens group actuator. The extended position allows movement for the lens group actuators340,341.

An optical image stabilizer341is configured to move the first lens group320—in an embodiment, the optical image stabilizer341is configured to move the autofocus actuator340together with the first lens group320. The optical image stabilizer341is an example of a lens group actuator. In an embodiment, the optical image stabilizer341is attached to the first lens group or to the lens barrel; whereas the autofocus actuator340is configured to move the image stabilizer341and the first lens group320. In an embodiment, the autofocus actuator340is electromechanically connected to the optical image stabilizer341, under the autofocus actuator340on the component stack.

According to an embodiment, the retractable element311suspends the structure of the at least one lens group actuator340,341and at least portion of the first lens group320. The retractable element311may comprise a frame that enables attaching the first lens group320or the at least one lens group actuator340,341to the retractable element311. In an embodiment, the retractable element311is configured to move, for example, on a rail or similar structure that guides the movement.

A second actuator310is configured to move the first lens group320along the optical axis301between the active and inactive positions. The second actuator310is configured to adjust the distance between at least one lens group actuator340,341and the image sensor group350. The first lens group320and the at least one lens group actuator340,341have the active position and the inactive position in relation to the image sensor group350along the optical axis301. In the active position the first lens group320and the at least one lens group actuator340,341protrude from the device body300along the optical axis301. In an embodiment, the actuator is a lifting mechanism that may comprise mechanical elements such as a lever that the user of the device applies in order to alter the distance between the first lens group320and the image sensor group350between active and inactive positions. In an embodiment, the lifting mechanism is a transmission system.

The image sensor group350resides on the optical axis, the image sensor350being on an image plane. The image sensor350is arranged on the optical axis to receive the image from the first lens group320. A focal plane is a plane where object appears in focus. In an embodiment, the first lens group320is tilted in the direction that reduces the effect of detected shaking to achieve optical image stabilization. The tilted first lens group320causes the focal plane to tilt as well, wherein the focal plane and the image sensor350are not aligned. The image sensor350comprises, for example, a plurality of light sensing elements that measure the light captured by the light sensing elements to form an image of pixels. In an embodiment, the image sensor group350comprises the field flattening lens351. The field flattening lens351corrects the focal plane projection error caused by tilting the first lens group320. In an embodiment the image is stabilized by tilting and shifting the lens. In an embodiment the image is stabilized by shifting the lens. In an embodiment the image is stabilized by moving the image sensor or the image sensor group350. The image sensor group may be defined by comprising an image sensor, an image sensor with one static lens or an image sensor with more than one static lenses.

In one embodiment the field flattening lens351is immovably connected to the image sensor350. The field flattening lens351does not tilt with the first lens group320; it is arranged to flatten the focal plane to the image plane at any predefined tilt angle of the first lens group320. The effect is achieved by designing the flattener lens rather than moving the image plane, image sensor350or by moving another element to counteract the tilted first lens group320. The field flattener lens flattens the field curvature of the first lens group320, wherein the curve is defined by series of points caused by varying tilting angle. The shape of the field flattener lens351may be calculated or selected from several alternatives that allow flattening of the focal point or the focal plane to the image plane when the first lens group320is in the tilted position. The tilt compensated by the field flattening lens351may be dynamic due to movement of the first lens group320, for example movement caused by optical image stabilization; or static tilt, for example residual tilt from the manufacture process.

The field flattening lens351has a concave shaped surface on the side opposite to the image sensor350, as illustrated inFIG. 3a. This structure allows for an improved optical design and thinner shape of the imaging apparatus, since the concave part does not require usual longer distance between the image sensor350and the lens barrel320, and the concave shape provides space for the first lens group320to be retracted further inside the device in the inactive state.

The image sensor group350is mounted on the circuit board370. The camera hardware370may comprise at least one of: a processor, a controller, a memory, or a sensor such as a gyroscope. A wiring, such a flex cable380may connect the imaging apparatus to the electronic device.

According to an embodiment, the field flattening lens351can be glued directly to the image sensor350. This removes an air gap between the lens351and the sensor350, which can improve the optical qualities of the system by removing unwanted refraction. In an alternative embodiment, the field flattening lens351can be attached to the image sensor350or the circuit board370on which the image sensor350is mounted with mechanical elements on (or near) two or more edges of the image sensor350. In this embodiment, an air gap is provided between the image sensor350and the field flattening lens351.

Although the field flattener lens351is illustrated as the only lens in the second lens group attached to the image sensor350, in various embodiments more optical elements, for example other lenses and filters, may be included in this group and the image sensor group. The field flattener lens351is the top lens of the image sensor group and may not be attached to the image sensor directly.

FIG. 3bshows the imaging apparatus in the inactive position. In the inactive position a portion of the one lens group actuator341is at the same level with the image sensor group350, perpendicular to the optical axis301. According to an embodiment, the first lens group320and the at least one lens group actuator340,341are inside the device body300. The lens is retracted, as the first lens group320is brought near the image sensor group350. The lens group actuator lowered to the level of image sensor group350may be the autofocus actuator340or the optical image stabilizer341, wherein the two lens group actuators may be stacked. In an embodiment, the lower lens group actuator is an autofocus actuator340or an optical image stabilizer341.

The previous embodiment showed two-group optics, where the components are in the inactive position at a distance shorter than typical functional clearances. Examples of functional clearances are autofocus stroke, tolerance margins or the back focal length. The image sensor group remains static, whereas the first lens group is able to move vertically, along the optical axis. In an embodiment, the image sensor group and at least one lens group actuator are nested in the inactive position.

FIGS. 4aand 4billustrate an embodiment, where the image sensor group450is movable in relation to the first lens group420and the device body. The device body comprises a transparent front surface400and an opaque rear surface410. The first lens group420is attached inside the device body facing the transparent front surface400. The first lens group may be attached to the device body by suspending from at least one lens group actuator440,441. The optical field of vision403of the imaging apparatus passes through the transparent surface400.FIG. 4ashows the active position, wherein the image sensor group450protrudes from the device body along the optical axis401. A retractable element411covers the imaging apparatus structure. The retractable element411protrudes from the device body causing a distance between the first lens group420and the image sensor group450. The image sensor group450is attached to the retractable element411. A wiring, such a flex cable480connects the image sensor group to the imaging apparatus.

In the inactive position the image sensor group450is inside the device body, as illustrated inFIG. 4b. In this example the device body is flush without any protrusions from the imaging apparatus. In an embodiment, the design may allow different shapes to be used in the context of retractable element.

The lens group actuator may be a voice coil actuator, a piezo actuator or a shape memory alloy actuator. In an embodiment, the actuator has a circular shape and the image sensor group fits inside the actuator perimeter. The lens group actuator may surround the image sensor group.

In an embodiment, the image sensor group comprises a curved image sensor550, as illustrated inFIG. 5. The curved sensor550functions with the tiltable lens barrel520as the curvature of the sensor550follows the focal plane projection. In an embodiment, correcting the focal plane projection error with the field flattener lens may not be required. The space required by the inactive position may be further reduced. The lens group actuator541may be lowered to the same plane as the curved sensor550. The level is defined as being perpendicular to the optical axis501. In an embodiment, a functional portion of the lens group actuator541is at the same level as the image sensor550or the image sensor group.

The retractable lens structure utilizes the available space around the image sensor group. For a flat device the height of the imaging device must be minimized. In this context the improvement in the scale of 0.01 mm difference of the imaging device's size may be considered an improvement. The reduced size of a single component may have an effect to other components in the electronic device, for example, in how other components are positioned inside the device.

FIGS. 6aand 6bschematically illustrate example layouts of the first lens group620and the field flattening lens651positioned on the image sensor surface650. The lenses in these embodiments are illustrated in an active position, and the direction of light is indicated with lines. The lens layout according to these embodiments may be part of the imaging apparatus of any of the embodiments described above. In the embodiment shown onFIG. 6a, the field flattening lens651has a spherical concave shape on the side opposite to the image sensor surface650. This corrects the focal plane projection error caused by tilting the first lens group620comprising five lenses each having two surfaces, including four aspherical surfaces and six spherical. The lens651may be attached to the image sensor surface650with glue.FIG. 6bshows an embodiment wherein the field flattening lens651has an aspherical concave shaped surface opposite to the image sensor650. The lens651also has a curved surface near the image sensor surface650, providing an air gap between the two elements. The aspherical concave shape of the upper surface provides the ability to fine-tune the optical design of the system, including the lens group620comprising four lenses which all have aspherical surfaces. The embodiments shown onFIGS. 6a-6bare an example only and should not be interpreted as limiting the possible implementations.

An additional technical effect of the combination of a field flattening lens having a concave upper surface attached to the image sensor, with the retractable lens group that can move in and out of the active position, is further tolerance to potential tilt and movement errors caused by repeated activation and deactivation of the camera.

According to an aspect, an imaging apparatus is disclosed. The imaging apparatus comprises: a retractable first lens group on an optical axis; at least one lens group actuator configured to move the retractable first lens group along the optical axis between an active position and an inactive position; an image sensor on the optical axis; and a second lens group comprising at least one lens immovably connected to the image sensor. In the active position the retractable first lens group resides at a predetermined distance from the second lens group and the image sensor, and in the inactive position the retractable first lens group resides in proximity to the second lens group. The second lens group comprises a field flattening lens having a concave shaped surface on a side opposite to the image sensor.

The predetermined distance may vary depending on the layout of the lens groups and may be between 0.1 and 5 mm. In the inactive position, the retractable first lens group resides in proximity to the second lens group at a closer distance than the predetermined distance of the active position. The distance may be between 0.01 mm and 2 mm.

In an embodiment, the field flattening lens is configured to correct a focal plane projection error caused by tilting of the first lens group.

In an embodiment, alternatively or in addition to the above embodiments, the field flattening lens has an aspherical concave shaped surface on a side opposite to the image sensor.

In an embodiment, alternatively or in addition to the above embodiments, the second lens group is immovably connected to the image sensor with glue.

In an embodiment, alternatively to the above embodiment, the second lens group is immovably connected to the image sensor with mechanical elements positioned at two or more edges of the image sensor.

In an embodiment, alternatively or in addition to the above embodiments, the retractable first lens group comprises a lens barrel.

In an embodiment, alternatively or in addition to the above embodiments, the second lens group comprises a single flattening lens.

In an embodiment, alternatively to the above embodiment, the second lens group also comprises an infrared filter.

In an embodiment, alternatively or in addition to the above embodiments, the imaging apparatus comprises a guide rail configured to guide the retractable first lens group between the active position and the inactive position.

In an embodiment, alternatively or in addition to the above embodiments, in the inactive position a portion of at least one lens group actuator is at the same level as the image sensor group, perpendicular to the optical axis.

In an embodiment, alternatively or in addition to the above embodiments, the lens group actuators comprise an autofocus actuator or an optical image stabilizer.

In an alternative embodiment, the lens group actuators comprise both an autofocus actuator and an optical image stabilizer.

In an embodiment, alternatively or in addition to the above embodiments, the imaging apparatus comprises a device body. The image sensor group is attached inside the device body; the retractable first lens group and the at least one lens group actuator are movable along the optical axis in relation to the image sensor group and the device body. In the active position the first lens group and the at least one lens group actuator protrude from the device body along the optical axis. In the inactive position the retractable first lens group and the at least one lens group actuator are inside the device body.

In an embodiment, alternatively or in addition to the above embodiments, at least one of the lens group actuators is a voice coil actuator, a piezo actuator or a shape memory alloy actuator.

According to an aspect, a device is disclosed. The device comprises a device body having a retractable element operable in an active position and an inactive position; a first lens group on an optical axis attached to the retractable element; an image sensor on the optical axis; a second lens group comprising a field flattening lens immovably connected to the image sensor; and a lifting mechanism configured to move the retractable element between the active position and the inactive position. In the active position the retractable element protrudes from the device body causing a distance between the first lens group and the second lens group; in the inactive position the retractable element is inside the device body; and the field flattening lens has a concave shaped surface on a side opposite to the image sensor.

In an embodiment, the device comprises at least one lens group actuator configured to move the first lens group. The at least one lens group actuator is selected from an autofocus actuator and an optical image stabilizer.

In an embodiment, in addition to the above embodiment, the image sensor is attached inside the device body; the first lens group and the at least one lens group actuator are connected to the retractable element and the first lens group and the at least one lens group actuator are movable along the optical axis in relation to the image sensor group and the device body.

According to an aspect, a device is disclosed. The device comprises a device body having a retractable element operable in an active position and an inactive position; a first lens group on an optical axis; an image sensor on the optical axis attached to the retractable element; a second lens group comprising a field flattening lens immovably connected to the image sensor; and a lifting mechanism configured to move the retractable element between the active position and the inactive position. In the active position the retractable element protrudes from the device body causing a distance between the first lens group and the second lens group. In the inactive position the retractable element is inside the device body. The field flattening lens has a concave shaped surface on a side opposite to the image sensor.

In an embodiment, the device body of the device according to the aspect above comprises a transparent surface. The first lens group is attached inside the device body facing the transparent surface and an optical field of vision passing through the transparent surface; and the image sensor is attached to the retractable element. In this embodiment, the image sensor and the second lens group are movable in relation to the first lens group and the device body. In the active position the image sensor and the second lens group protrude from the device body along the optical axis; and in the inactive position the image sensor and the second lens group are inside the device body.

In an embodiment, alternatively or in addition to the above embodiment, the device comprises at least one lens group actuator connected to the first lens group and selected from an autofocus actuator and an optical image stabilizer.

An imaging apparatus is disclosed, comprising: a first lens group on an optical axis; at least one lens group actuator configured to move the first lens group; an image sensor group on the optical axis; and a second actuator configured to adjust the distance between the at least one lens group actuator and the image sensor group, the first lens group and the at least one lens group actuator having an active position and an inactive position in relation to the image sensor group along the optical axis. In the inactive position a portion of the one lens group actuator is at the same level with the image sensor group, perpendicular to the optical axis. In an embodiment, the at least one lens group actuator is an autofocus actuator or an optical image stabilizer. In an embodiment, the first lens group actuator is an autofocus actuator and the second lens group actuator is an optical image stabilizer. In an embodiment, in the inactive position a portion of the autofocus actuator is at the same level with the image sensor group. In an embodiment, in the inactive position a portion of the autofocus actuator and a portion of the optical image stabilizer are at the same level with the image sensor group. In an embodiment, the imaging apparatus comprises a device body, wherein the image sensor group is attached inside the device body; the first lens group and the at least one lens group actuator are movable along the optical axis in relation to the image sensor group and the device body, wherein in the active position the first lens group and the at least one lens group actuator protrude from the device body along the optical axis; and in the inactive position the first lens group and the at least one lens group actuator are inside the device body. In an embodiment, the imaging apparatus comprises a device body having a transparent surface, the first lens group being attached inside the device body facing the transparent surface and an optical field of vision passing through the transparent surface; and the image sensor group is movable in relation to the first lens and the device body, wherein: in the active position the image sensor group protrudes from the device body along the optical axis; and in the inactive position the image sensor group is inside the device body. In an embodiment, the at least one lens group actuator is a voice coil actuator, a piezo actuator or a shape memory alloy actuator. In an embodiment, the image sensor group comprises a field flattener lens. In an embodiment, image sensor group comprises a curved image sensor.

A device is disclosed, comprising: a device body having a retractable element; a first lens group on an optical axis and at least one lens group actuator configured to move the first lens group; an image sensor group comprising an image sensor on the optical axis; the retractable element having an active position and an inactive position. In the active position the retractable element protrudes from the device body causing a distance between the first lens group and the image sensor group; in the inactive position a portion of the at least one lens group actuator is at the same level, perpendicular to the optical axis, with the image sensor group; and comprising a lifting mechanism configured to move the retractable element between the active position and the inactive position. In an embodiment, the at least one lens group actuator is an autofocus actuator or an optical image stabilizer. In an embodiment, the device comprises two lens group actuators, wherein the first lens group actuator is an autofocus actuator and the second lens group actuator is an optical image stabilizer. In an embodiment, the device body comprises a transparent surface, the first lens group is attached inside the device body facing the transparent surface and an optical field of vision passing through the transparent surface; and the image sensor group is attached to the retractable element, wherein the image sensor group is movable in relation to the first lens group and the device body, wherein: in the active position the image sensor group protrudes from the device body along the optical axis; and in the inactive position the image sensor group is inside the device body. In an embodiment, the image sensor group is attached inside the device body; the first lens group and the at least one lens group actuator are connected to the retractable element and the first lens group and the at least one lens group actuator are movable along the optical axis in relation to the image sensor group and the device body.

A system is disclosed, comprising: a first lens group on an optical axis; an image sensor group on the optical axis; and at least one lens group actuator configured to move the first lens group; a second actuator configured to adjust the distance between the at least one lens group actuator and the image sensor group along the optical axis, the first lens group and the at least one lens group actuator having an active position and an inactive position in relation to the image sensor group along the optical axis, wherein: in the inactive position a portion of the one lens group actuator is at the same level with the image sensor group, perpendicular to the optical axis. In an embodiment, the at least one lens group actuator is an autofocus actuator or an optical image stabilizer. In an embodiment, the system comprises two lens group actuators, wherein the first lens group actuator is an autofocus actuator and the second lens group actuator is an optical image stabilizer, wherein in the inactive position a portion of the autofocus actuator and a portion of the optical image stabilizer are at the same level with the image sensor group. In an embodiment, the system comprises a device body, wherein the image sensor group is attached inside the device body; the first lens group and the at least one lens group actuator are movable along the optical axis in relation to the image sensor group and the device body, wherein: in the active position the first lens group and the at least one lens group actuator protrude from the device body along the optical axis; and in the inactive position the first lens group and the at least one lens group actuator are inside the device body. In an embodiment, the system comprises a device body having a transparent surface, the first lens group being attached inside the device body facing the transparent surface and an optical field of vision passing through the transparent surface; and the image sensor group being movable in relation to the first lens and the device body, wherein: in the active position the image sensor group protrudes from the device body along the optical axis; and in the inactive position the image sensor group is inside the device body.

An example of the apparatus or a system described hereinbefore is a computing-based device comprising one or more processors which may be microprocessors, controllers or any other suitable type of processors for processing computer executable instructions to control the operation of the device in order to control one or more sensors, receive sensor data and use the sensor data. Platform software comprising an operating system or any other suitable platform software may be provided at the computing-based device to enable application software to be executed on the device.

The computing-based device may comprise an input/output controller arranged to output display information to a display device which may be separate from or integral to the computing-based device. The display information may provide a graphical user interface, for example, to display hand gestures tracked by the device using the sensor input or for other display purposes. The input/output controller is also arranged to receive and process input from one or more devices, such as a user input device (e.g. a mouse, keyboard, camera, microphone or other sensor). In some embodiments the user input device may detect voice input, user gestures or other user actions and may provide a natural user interface (NUI). This user input may be used to configure the device for a particular user such as by receiving information about bone lengths of the user. In an embodiment the display device may also act as the user input device if it is a touch sensitive display device. The input/output controller may also output data to devices other than the display device, e.g. a locally connected printing device.

The term ‘computer’ or ‘computing-based device’ is used herein to refer to any device with processing capability such that it can execute instructions. Those skilled in the art will realize that such processing capabilities are incorporated into many different devices and therefore the terms ‘computer’ and ‘computing-based device’ each include PCs, servers, mobile telephones (including smart phones), tablet computers, set-top boxes, media players, games consoles, personal digital assistants and many other devices.

Any range or device value given herein may be extended or altered without losing the effect sought.