CamCyclopedia
Contents
- Definition and principles of OIS
2. Galaxy camera OIS
3. Notes
Definition and principles of OIS
1. What is OIS?
Optical image stabilization (OIS) technology is one of the main image stabilization technologies alongside digital image stabilization (DIS) and electrical image stabilization (EIS).
Taking photos in low light counts for a low shutter speed to take in more light. But your photo may result in a motion blur because of unsteady hands or some vibration. This is where image stabilization comes in to help you get crisp and stable pictures.
2. Principles of OIS
The diagram above is a simple depiction of how OIS works. When you take a photo or video, your phone's gyroscope sensor sends out data on the magnitude of shaking to the Micro Controller Unit (MCU).
The MCU sends a target signal to the Driver IC to move the lens or sensor in the opposite direction of the tilt.
Finally, the Driver IC uses the target signal to signal the actuators in the module to move or tilt the lens or sensor to compensate for the shake.
Let’s take a look at the OIS system and structure of the Galaxy camera.
3. Types of OIS
OIS categorizes types based on the moving object and its way of moving. Here's how it works.
- Lens Shift OIS: Corrects unsteadiness by moving the lens in a direction opposite to the incline of the shake
- Sensor Shift OIS: Corrects unsteadiness by moving the sensor in a direction opposite to the incline of the shake
- Module Tilt OIS: Corrects unsteadiness by tilting the lens and sensor to a direction opposite to the incline of the shake
OIS in Galaxy Camera
Let’s take a look at the OIS system and structure of the Galaxy camera.
Galaxy OIS System
1. Gyro Sensor
Gyro sensors used in mobile phones are a type of MEMS sensor made in a semiconductor process line-up. They are low-powered and small, making them optimized for mobile use. The gyro sensor collects up to 6600 times of shaking scenario data every second and provides this information to the AP or OIS MCU.
2. OIS Operation (OIS MCU)
The OIS driver chip in the camera module operates the lens or prism based on the unsteadiness information from the gyro sensor.
The wide-angle camera in current Galaxy models employs the lens shift OIS, where the lens moves horizontally. There is increased image signal stability by anchoring the image sensor and the OIS also happens to be high-performing and ultra-compact.
Folded zoom cameras, where the optical path can be bent to minimize "camera bumps," use prism tilt OIS that rotates the prism to correct any unsteadiness.
3. OIS correction in videos (VDIS+OIS)
Videos require stabilization of 30 to 120 frames per second in continuity. So, OIS stabilization is additionally buttressed by Video Digital Image Stabilization (VDIS) to achieve a much better image quality.
Structure of Galaxy OIS camera module
1.Actuator source of OIS
Galaxy uses a Voice Coil Motor (VCM) actuator, allowing for a very quick response rate and a high degree of design freedom.
The VCM method applies the Lorentz force of a magnetic field and conducting wire using a magnet and a coil.
The direction of the actuator force is determined by reversing the direction of the current according to Fleming's Left Hand Rule. This lets Galaxy operate the OIS driver at 30000 times per second (30 kHz) in real-time.
2. Structure of OIS Actuator
The lens needs to be operated in three directions i.e. the X, Y and Z (AF, Auto Focus) axes and avoid any rotation. Galaxy cameras engage something called a ‘ball guide’ to do this.
This results in a precise shift that does not even allow for 0.2 degrees of tilt when the X, and Y axes and AF of OIS are in use.
This type of ball guide design has a very stable and highly rigid structure. Only Samsung owns the patent rights to this technology.
Sometimes when you hold and shake your phone, you may hear a noise as the lens barrel collides with the actuator.
This motion does not affect the performance at all, but we have applied a softer shock absorbent elastomer to the parts prone to the collision to avoid any sound on contact.
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Notes
[1] OIS technology is only available in some models and certain cameras like Galaxy S22 Ultra-wide camera, tele camera, etc.
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