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【Fun Fact】 My phone makes a knocking sound when shaken, is it broken?

Level 10

One day, you may notice a rattling sound coming from your phone when shaken, don't panic just yet.

First, try to recall if you've dropped your phone recently or if there is any visible damage to its exterior.

If your phone hasn't endured any of the above mishaps, try activating the camera mode and then shake the phone again.

If you don't hear the knocking sound while the camera is active, there's a 99.9% chance your phone is fine. The knocking sound usually comes from the OIS (Optical Image Stabilization) component of the camera lens.



Where does the knocking sound come from?

In fact, it's not just new phones that may encounter this issue. Many DSLR camera users have also questioned why their lenses make a knocking sound when shaken after purchasing new ones.

Some even go as far as sending their phones or lenses to service centers to identify the problem, only to realize it's all a misunderstanding.

The knocking sound is simply the result of displacement in the optical image stabilization (OIS) floating component, which does indeed sound like a loose part.

You can hear this sound when shaking because the components of the optical image stabilization are in a relaxed state.

You can also search online for your phone's specifications to see if the camera boasts optical image stabilization. If it does, shaking the phone when the camera isn't active will likely produce a slight knocking sound. For example, the ROG Phone 8 exhibits this phenomenon.


Principles of Image Stabilization Systems

Image stabilization systems can be broadly categorized into two types: Optical Image Stabilization (OIS) and Electronic Image Stabilization (EIS).

OIS, or Optical Image Stabilization, typically involves a floating component inside the device. This component moves in the opposite direction of the detected motion, thereby counteracting the shake to achieve more precise focusing. The floating parts in optical stabilization can be the photosensitive element itself or a lens element within the camera assembly, depending on the manufacturer's design.

EIS, operates similarly to OIS but relies on algorithms within the device to achieve stabilization. However, EIS often involves cropping a portion of the frame to compensate for motion.


OIS and EIS each have their own advantages and disadvantages.

Optical Image Stabilization (OIS) generally provides better image quality and superior stabilization compared to Electronic Image Stabilization (EIS). However, the placement of the floating component required for OIS can add bulk to the device, making it more challenging and costly for manufacturers. Additionally, there may be audible noises during movement, which could be considered a drawback.

On the other hand, Electronic Image Stabilization (EIS) offers the advantage of compactness compared to OIS. However, the image quality may not be as high as with OIS.

Some devices may boast the incorporation of both stabilization technologies simultaneously.


Why does Optical Image Stabilization make a clicking sound?

The clicking sound in Optical Image Stabilization (OIS) occurs because of the floating component inside the device. This component, which is typically part of the image sensor or a lens element, is suspended in a magnetic field when powered on, and it counteracts deviations in various directions.

When the device is not powered on, the floating component naturally rests in its suspended space. When the device is shaken, the component moves within this space, resulting in the clicking sound.

You might wonder why it doesn't remain suspended indefinitely. The reason is that the suspension of the OIS component consumes power, so if the camera of the phone is not in use, the floating component of the OIS system will automatically enter a sleep mode to conserve power.


↪︎ This is probably how the suspended Optical Image Stabilization component behaves when it's in sleep mode. In terms of working hours, it's probably one of the most leisurely units inside the phone.

The same applies to camera lenses with optical image stabilization. If there's no half-pressed shutter button for continuous focusing or activating full-time autofocus, the floating components might go into sleep mode after a few seconds to save power. When the suspended lens elements are released from suspension, they may produce some sound, and you might even see them dropping in the camera's viewfinder as the suspension is released.


Will the suspended components be damaged by shaking?

Under normal use, it's unlikely for the shock-absorbing suspended components to be damaged by shaking unless you leave the phone in a continuously vibrating position for an extended period. However, I think other functions of the phone would likely be compromised before the camera components are damaged.


Benefits of image stabilization:

In conditions where there is insufficient light, requiring longer exposure times, or when the handheld device is unstable, it can lead to blurry images. Devices equipped with optical image stabilization (OIS) typically experience significant improvements in performance during night photography, handheld motion tracking, focusing with long focal lengths, and focusing at close distances.



↪︎ The ultimate goal is to capture clear photos even when there is hand shake.


The level of image stabilization

Some manufacturers use terms like "levels" or "axes" to indicate their image stabilization technology, and we can think of these numbers as "the directions of shake it can handle."

The higher the level or number of axes, the more directions of movement the device can counteract.

In addition to countering roll, pitch, and yaw movements, image stabilization may also include additional translations in the horizontal and vertical directions, depending on how the manufacturer designs it. Generally, a higher level or more axes indicated usually means better stabilization capability.