What Is a Camera Module?
A camera module is an industrial device similar in structure to a consumer single-lens reflex camera.
A camera module can be divided into a lens and a camera. A part called a mount connects the lens to the camera, and the lens can be interchanged as long as the mounting standard is the same. There are two photographic elements in a camera: CMOS and CCD. There are also two image cropping methods: global shutter and rolling shutter.
Uses of Camera Modules
Small camera modules are used as cameras in smartphones and PCs, ATMs, and for facial recognition in vending machines and ticket machines. Large cameras are used as security, in-vehicle, and industrial equipment for inspection and measurement purposes.
Principle of Camera Modules
In-camera modules, light entering through the lens is formed into an image on the photographic element and converted into an electrical signal to acquire an image.
There are two main types of photographic elements: CMOS and CCD. CMOS can operate with low power consumption, while CCD has a global shutter, as described below. Both types of sensors convert light entering the photodiode into electrical signals, which are then converted into stable digital signals with noise suppressed by CDS, AGC, and ADS installed behind the photodiode. The digital signal is output as image data by the image processing engine.
The difference between a global shutter and a rolling shutter is explained below.
With a global shutter, light entering numerous photodiodes is converted into an electrical signal simultaneously. A rolling shutter converts light into electrical signals in a spiral-like sequence. In principle, a rolling shutter will take a distorted image of a subject tilted at an angle when capturing a subject that is moving quickly across the image. The images that can be acquired by the camera modules can be color or monochrome.
In a color sensor, photodiodes capable of discriminating a single color among the three colors blue, red, and green are arranged in a nested array called a Bayer sensor. A single photodiode can only obtain color information of a single color, but by obtaining information from surrounding photodiodes responsible for other colors, a single photodiode can pseudo-obtain information about all three colors.
Camera Modules Market
The global camera modules market is strong as of 2020 and is expected to continue to grow at a high rate.
Cameras in smartphones and other mobile devices began to shift to multi-cameras around 2015, evolving from single to dual, triple, and quad cameras.
In addition to higher image quality, AF, zoom, and wide-angle functions, the use of sensor camera modules such as ToF and LiDAR is expected to expand further, including improved AF performance in dark areas, improved face recognition accuracy, and use in virtual reality (VR) and augmented reality (AR) functions.
In the automotive market, the number of cameras installed per vehicle for advanced driver assistance systems (ADAS) is rising.
In the consumer electronics and industrial fields, demand is also expected to increase for the installation of smart products, assistant robots, and drones to meet the needs for manpower saving, security, and remote control.
The evolution of the lenses that make up camera modules, the use of new materials, and the development of technologies such as MEMS (micro-electro-mechanical systems) are increasing the value of camera modules.
Camera Modules for Automotive Applications
Demand for automotive camera modules is rapidly shifting from a focus on monitoring applications for peripheral blind spots that replace conventional mirrors to sensing applications, driven by growing demand for advanced safety assist systems (ADAS) and automated driving.
Together with advanced optics, image processing, and communication technologies, they play a major role in realizing a “safe and secure” automotive society.
There are various types of in-vehicle camera modules, as follows:
- A Front Monitoring Camera Modules
Monitors the car in the direction of travel and assists in safe driving. - Camera Modules for Drive Recorders
Used to record video of the situation in front of and inside the vehicle at all times while the vehicle is moving or stopped. - Driver Monitoring Camera Modules
Used to monitor the driver while driving and to predict hazards such as dawdling or falling asleep at the wheel. - Surround View Camera Modules
This module is used to eliminate blind spots around the vehicle and to ensure safety.