Magnetic Camera Brake
20240040218 ยท 2024-02-01
Inventors
- Zachary W. Birnbaum (Santa Clara, CA, US)
- Andrew S. Jozefov (San Francisco, CA, US)
- Scott W. Miller (Los Gatos, CA, US)
Cpc classification
H04N23/54
ELECTRICITY
International classification
H04N23/54
ELECTRICITY
Abstract
Various magnetic camera brake embodiments are disclosed. According to some embodiments, the magnetic camera brakes leverage a magnetic attraction (or repulsion) force between an iron and magnetic body to hold the moving camera components at a desired focus positioneven under high amplitude acceleration loads. When high disturbance rejection is desired, the magnet attracts the camera to the desired focus position (e.g., an infinity focus position) with enough force to overcome approximately 10 g's of external acceleration. In some embodiments, ball bearings may be used to provide constraints in up to 5 degrees of freedom (e.g., all but z-axial translation along the optical axis), so there is no rocking of the image sensor (or lens barrel). When macro photos are desired of subjects closer than the hyperfocal distance, an actuator mechanism may be configured to pull the image sensor out of the desired focus position and into the macro focus region.
Claims
1. A camera module, comprising: a sensor configured to capture an image; a lens with an optical axis, wherein the lens is configured to focus light from an object onto the sensor to capture the image, and wherein the sensor is movable relative to the lens along the optical axis; and a magnetic brake that holds the sensor relative to the lens in a desired focus position.
2. The camera module of claim 1, wherein the desired focus position is at an infinity focus position for the camera module.
3. The camera module of claim 1, further comprising: a lens holder that holds the lens; and a sensor carrier that carries the sensor.
4. The camera module of claim 3, wherein the magnetic brake comprises: a magnet included in the lens holder; and a ferromagnetic material included in the sensor carrier.
5. The camera module of claim 3, wherein the magnetic brake comprises a magnet included in the sensor carrier, and a ferromagnetic material included in the lens holder.
6. The camera module of claim 3, wherein the magnetic brake comprises two magnets, wherein a first magnet is included in the sensor carrier and a second magnet is included in the lens holder.
7. The camera module of claim 6, wherein the first magnet and second magnet are configured to attract each other, thereby pulling the sensor carrier towards the desired focus position.
8. The camera module of claim 3, further comprising a housing, wherein the magnetic brake comprises two magnets, wherein a first magnet is included in the sensor carrier and a second magnet is included in the housing.
9. The camera module of claim 8, wherein the first and second magnet are configured to repel each other, thereby pushing the sensor carrier towards the desired focus position.
10. The camera module of claim 5, wherein the ferromagnetic material comprises one or more of: alnico, bismanol, caesium hexafluorocobaltate(IV), californium, chromium(IV) oxide, cobalt, cobalt ferrite, complex oxide, dysprosium, erbium, Europium hydride, fernico, ferrite (magnet), gadolinium, gallium manganese arsenide, greigite, heusler compound, hexagonal ferrite, holmium, iron, KS steel, magnadur, magnetic 2D materials, magnetic semiconductor, magnetite, metglas, MKM steel, monostrontium ruthenate, neodymium magnet, nickel, permalloy, polder tensor, rare-earth magnet, samarium-cobalt magnet, sendust, suessite, terbium, uranium hydride, vicalloy, and yttrium iron garnet.
11. The camera module of claim 1, wherein the desired focus position comprises a locked position for the camera module.
12. The camera module of claim 1, further comprising an actuator mechanism that is configured to be able to release the magnetic brake from the desired focus position when activated.
13. The camera module of claim 12, wherein the actuator mechanism comprises a voice coil actuator.
14. The camera module of claim 3, further comprising a spring that provides a soft end stop for the sensor carrier at the desired focus position.
15. The camera module of claim 14, wherein the spring further comprises a spring bumper.
16. The camera module of claim 15, wherein the spring bumper is formed of a low durometer polymer material that is more compliant than the spring.
17. The camera module of claim 14, wherein the spring is configured to be in a partially compressed state when the sensor is in the desired focus position.
18. The camera module of claim 1, wherein the magnetic brake comprises a single magnet and a single corresponding aligned ferromagnetic material.
19. The camera module of claim 1, wherein the magnetic brake comprises a pair of magnets and a pair of corresponding aligned ferromagnetic materials.
20. The camera module of claim 1, wherein the magnetic brake comprises at least one pair of single polarization directional magnets oriented to attract one another.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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DETAILED DESCRIPTION
[0053] Various magnetic camera brake embodiments are disclosed herein. According to some such embodiments, the magnetic camera brakes leverage a magnetic attraction or repulsive force between an iron and magnetic body (or between multiple magnetic bodies) to lock the relative motion of moving camera components at a desired optical focus position (e.g., an infinity focus position)even under high amplitude acceleration loads.
[0054] When high disturbance rejection is desired, the magnet attracts the camera to a hyperfocal (i.e., infinity) focus position (which may, e.g., be at a hard stop or a soft stop position) with enough force to overcome approximately 10 g's of external acceleration. In some embodiments, ball bearings may be used to provide constraints in up to 5 degrees of freedom (e.g., all but z-axial translation along the optical axis), so there is no rocking of the image sensor (or lens barrel).
[0055] When macro photos are desired of subjects closer than the hyperfocal distance, an actuator mechanism may be configured to be strong enough to pull the image sensor out of the desired focus position that it is being held in by the camera brake(s) and into the macro focus region, when necessary.
[0056] Turning now to
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[0058] Camera module 100.sub.1 may further include a dynamic flex 110 surrounding the sensor carrier 108, an infrared cutoff filter 112, a molded end stop 116 to stops the translation of the sensor carrier 108 in the x- and y-axial directions in a drop or shock scenario, and a shield can 118, wrapped around the exterior of the camera module 100.sub.1. The camera module 100.sub.1 also includes an actuator mechanism 120, which may be comprised of: a preload plate 128, a rigid flex 130, a coil 126, a drive magnet 127, and a back iron plate 132.
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[0060] Turning now to
[0061] The various embodiments of magnetic camera brakes disclosed herein, e.g., involving a magnetic attraction or repulsive force between an iron plate and a magnetic body (or between multiple magnetic bodies), are configured to be able to hold or lock the relative motion of moving camera components at a desired optical focus positioneven under high amplitude acceleration loads. Thus, the embodiments disclosed herein achieve the best of both a fixed focus camera system and an autofocus camera system. That is, when high disturbance rejection is desired and the camera is being accelerated, the magnetic brake is able to attract the camera to the hyperfocal (i.e., infinity) focus position or some other desired focus position (sometimes referred to herein as a locked position) with enough force to overcome the external acceleration, thereby enabling high-quality photos and videos to be taken in such use cases. According to some embodiments, the desired focus or locked position may include an intentional nominal gap 204 (as shown in
[0062] Conversely, when macro or close up photos are desired, e.g., photos of subjects that are located closer to the camera than the hyperfocal distance, some embodiments disclosed herein comprise actuator mechanisms (e.g., actuator mechanism 120) that are strong enough to pull the image sensor out of the desired focus or locked position in which it is being held by the magnetic brake and into the macro focus region. Another benefit of some of the embodiments disclosed herein is that the magnetic brake mechanisms 136 are able to lock the camera in position and hold focus at the hyperfocal distance (which is a predominant use case across most types of photography) without actively powering the actuator, thus, the braking mechanisms disclosed herein require very low power consumption to operate. The camera module 100.sub.2 in
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[0064] The movement of the sensor carrier 108 relative to the lens barrel 102 is constrained in 5 degrees of freedom (i.e., all but the positive z-axial direction along the optical axis 138) by the ball bearings 202. Thus, there is no rocking of the sensor carrier 108 as it moves. The lens barrel 102 is firmly attached to the top of the ball bearing raceway, thereby providing a hard stop in the positive z-axial direction and constraining the 6th degree of freedom. This enables high-quality photos and videos to be capturedeven in high acceleration photography environments.
[0065] One of the magnetic brakes 136.sub.2 of
[0066] In the position where the magnet 124 is at its closest-possible position to the iron plate 122, the sensor carrier 108 and the lens holder 102 are said to be held in a desired focus or, in this case, locked position. In the desired focus position, a motion of the sensor carrier 108 relative to the lens holder 106 is prevented under most high amplitude acceleration loads (excluding shock forces on the order of hundreds or thousands of g's). In the desired focus position, the sensor carrier 108 comes to a hard end stop relative to the lens barrel 102, and the distance between the sensor in the sensor carrier 108 and the lens in the lens barrel 102 is the hyperfocal distance (i.e., the distance beyond which nearly all objects can be brought into focus). Therefore, the desired focus position is also the infinity focus position of the camera module 100.sub.2.
[0067] When it comes to rattle acoustics, the camera module 100.sub.2 remains silent when in the desired focus position and accelerated at a rate of approximately 10 g's or lower (which is representative of an acceleration that may be applied by a user tapping on an electronic device with such a camera module embedded in it). When it comes to power consumption, the magnetic brake 136.sub.2 locks the camera and holds the focus without powering the actuator mechanism 120 (see
[0068] In the event of a shock where the magnetic brake 136.sub.2 is released forcefully, the iron plate 122 simply separates from the magnet 124. When the shock is over, the sensor carrier 108 is magnetically attracted back to the infinity focus position. In other embodiments, the actuator mechanism 120 may also be used to actively drive the sensor carrier 108 back to the desired focus position. This is done quickly and without optically reestablishing the infinity focus position, since there is a physical datum to drive to. No mechanical parts of the camera module are stressed during this operation, and the camera module 100.sub.2 therefore recovers gracefully.
[0069] In some embodiments, the camera module 100.sub.2 may also exhibit improved disturbance rejection, which is a measure of how well the camera module can address unexpected accelerations that may cause the camera to lose its focus position. When high frequency acceleration load disturbances are experienced by the camera module 100.sub.2, magnetic brake 136.sub.2's attractive force increases the natural frequency of the camera module 100.sub.2, thereby allowing the camera module 100.sub.2 to more effectively attenuate and reject such high frequency acceleration loads. In some situations, the actuator mechanism 120 may also be used to push the sensor carrier 108 into the hard end stop in the positive z-axial direction (i.e., additive to the attractive force of the brake magnet 136.sub.2), in order to provide even greater disturbance rejection capabilities.
[0070] In the use case of macro image photography, i.e., photography of objects closer than the hyperfocal distance, the actuator mechanism 120 may pull the sensor carrier 108 out of the desired focus position and down (i.e., in the negative z-axial direction) into the macro focus position. Therefore, the actuator mechanism 120 may include an electromagnetic coil 126 that exerts a Lorentz force strong enough to overcome the attractive force of the magnet 124.
[0071] Turning now to
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[0073] Turning now to
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[0075] Putting the brake magnet on opposite side of the camera module (e.g., as compared to the embodiments illustrated in
[0076] For example, according to the illustrated embodiments, the L-shaped sensor carrier 108 piece is not attached anywhere on the right side of the camera module. So, adding a magnetic camera brake on the right side (i.e., the opposite side of ball bearings 202), as shown in
[0077] Turning now to
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[0079] Turning now to
[0080] To explain further, one challenge faced by fixed focus cameras is that, if they heat up (or cool down) significantly, the actuator mechanism may need to adjust the lens or sensor further to keep the camera in focus, e.g., if there is no optical stroke remaining. Thus, instead of pinning the magnetic brake 136.sub.6 to a hard end stop, embodiments such as
[0081] In some such embodiments, the infinity focus position may be at a partially-depressed state of the spring, i.e., not before spring contact and not when the spring is fully compressed. That is, there may be some amount of spring compression, wherein the magnetic force generated by the magnetic brake is in balance with the spring force applied by the spring bumper 602, e.g., with each being at approximately 50 mN of force in some embodiments. As may now be appreciated, the spring bumper 602 may provide an additional margin of movement for the sensor between the default desired focus position, e.g., an infinity focus position, and the hard stop in the positive-z axial direction (e.g., when the spring is fully compressed).
[0082] In some embodiments, to determine whether there is a need to apply athermalization to the camera's AF system, the image sensor itself could have temperature sensor to detect temperature anomalies, the circuit board could have temperature sensor, or the image signal processor (ISP) could analyze a captured image to determine if it is in focus, etc.
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[0085] When the sensor carrier is pinned up against the spring bumper, it makes the overall AF system stiffer. Thus, according to some embodiments, the AF system controller could have multiple modes of control, e.g., a main mode for when the spring is operating with normal stiffness, and then stiff mode for the end of the optical stroke range, when the system has higher stiffness. As may now be understood, the use of a spring bumper can increase the AF system's bandwidth at infinity focusand allow it to perform better vibration rejection.
[0086] Turning now to
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[0088] It is noted that the camera modules as described and illustrated herein may beneficially have a dynamic flex to route image sensor signals and feature a fixed lens with a moving image sensor carrier. However, in alternative camera module embodiments, the end stops (e.g., magnets/iron plates pairings) could be implemented on a lens shift camera as well, where the image sensor is fixed and the lens normally moves, and wherein the brake would stop the lens from moving (rather than stopping the sensor carrier from moving).
[0089] Although the aspects above have been described in considerable detail, numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.