Apple patent reveals new multi-coil voice coil motor drive architecture featuring all-new autofocus and more

It was reported in January by DigiTimes that Apple supplier Largan was to be the primary supplier of voice coil motors (VCMs) for iPhone 13. VCMs are used for camera imaging, autofocus, and optical image stabilization ( OIS) and the iPhone 13 provides Apple’s best and largest camera yet, including an all-new autofocus mechanism via VCM. The iFixit image forms their video reportage shown below illustrates the change in camera size from iPhone 12 to iPhone 13.

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The principle behind a VCM is to control the spring tension position by changing the direct current of the coil in the motor in a long term magnetic field, thereby causing up and down movement. Yesterday, the US Patent & Trademark Office issued an Apple patent application titled “Multi-coil voice coil motor drive architectureApple’s marketing for the iPhone 13 Pro, as featured below, points to a ‘brand new autofocus’ – which is derived from a new VCM which is likely the one revealed in the recently released patent for Apple.

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3x Apple iPhone 13 Pro brand new autofocus

Apple notes in their dossier that in recent years manufacturers have added more and more lenses to cameras to improve the quality of movies. Typically, a camera can use an actuator, such as a voice coil motor (VCM) actuator, to move the lenses relative to an image sensor. As cameras get more complicated, they get bigger and heavier, and more powerful actuators are needed to provide the required driving force. Traditional VCM actuators may be limited in power due to size and power source limitations associated with mobile devices. Thus, it is desirable to have VCM actuators with more efficient architectures to increase the output power.

Apple’s invention describes various techniques for a camera system comprising a VCM camera actuator with segmented coils. In some embodiments, the VCM actuator can include multiple coil segments to move a lens group relative to an image sensor along an optical axis to implement autofocus (AF) motion and tilt actions.

In some embodiments, the VCM actuator can include multiple coil segments to move the image sensor relative to the lens group along axes orthogonal to the optical axis. to perform image sensor shift or optical image stabilization (OIS) actions. Compared to traditional VCM actuators, the described VCM actuator segments a coil, such as an AF and / or OIS coil, into multiple segments each having an impedance lower than the total impedance of the coil as a whole.

In addition, the coil segments can be driven individually by respective currents. In this way, the VCM actuator can achieve larger currents in the coil segments for a given supply voltage, resulting in larger driving forces.

Apple’s patent FIG. 6A below illustrates a perspective view showing an example coil segment configuration of an actuator. Specifically, only the magnets and actuator coil segments (# 600) are shown.

In this example, the actuator may include two bipolar magnets # 602-603 and two unipolar magnets # 632-633. The four magnets can be arranged around the actuator, for example at 90 degrees to each other on a circle around the actuator. The actuator can include two concentrated AF coil segments (# 604 and 606), with coil segment # 604 being placed near bipolar magnet # 602 and coil segment # 606 adjacent to bipolar magnet # 603. By driving coil segments # 604 and # 606 with separate currents # 614 and # 616, the coil segments can interact with the magnetic field # 624 and # 626 of magnets # 602 and # 603 respectively to produce driving forces # 644 and # 646, in the directions shown in fig. 6A. The driving forces can move or tilt the lens group relative to the image sensor.

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4 Apple VCM fig.  6a

In some embodiments, the camera may include an OIS coil segmented into coil segments # 610 and # 611. In some embodiments, the coil segments can be placed under the unipolar magnets # 632-633, respectively.

The coil segments can be individually driven by the respective currents # 617 and # 618, which can interact with the magnetic fields # 627 and # 628 of the unipolar magnets # 632-633 to produce driving forces # 647 and # 648, in the directions shown in fig. 6A.

The driving forces 647 and 648 can offset the image sensor relative to the lens group on the image plane, for example along the Y and X axes, which are orthogonal to the optical axis of the lens group. The camera arrangement may allow for an autofocus (AF) camera system.

Patent of Appeal FIG. 6B below illustrates a top view of another example coil segment configuration of an actuator.

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5 x alternative VCM FIG.  6B

Apple’s patent FIG. 8 below is a 3D view of an example actuator with the outer shield hidden so that more of the mechanism can be seen.

6 Apple VCM patents fig.  8 & 12

Apple’s patent FIG. 12 above illustrates an example control diagram for implementing decoupled AF motion and tilt.

This is a detailed patent that engineers will appreciate, and you can view Apple’s patent application 20210314469 in its entirety. here.

Inventors

Bhide; Anish: Custom Silicon Engineer (former NVIDIA employer)

Shahrooz Shahparnia: Hardware architect

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