First, the lens receives the light of the scene, converts the light signal into an electrical signal through the lens and photosensitive element, and then processes the image through the ISP, and finally displays it on the screen.
The different components in the lens make the image show different effects. The components of each part play different roles. This article will introduce the mystery of each part.
Camera module composition
1.Overview of camera modules
The camera module is a highly integrated system that integrates multiple key components such as lenses, image sensors, image processing chips, voice coil motors (VCMs), infrared filters, and flexible printed circuit boards (FPCBs). These components work together to convert light into digital image signals, which are finally presented on the user’s screen. The performance of the camera module depends not only on the quality of individual components, but also on the coordinated optimization and overall design between them.
2.Camera imaging principle
The most basic principle of camera imaging is convex lens imaging. After light passes through the lens, a virtual image is formed, and the virtual image is transmitted to the screen for display.
The lens receives external light and hits the imaging module. By controlling the telescopic movement of the lens, a clearer or wider viewing angle image is achieved.
The entire camera module can be understood as a combination of lens and sensor. The lens is responsible for receiving light from various scenes, and the sensor is responsible for converting light into electrical signals that can be processed by the CPU and adjusting the color of the display output.
3. Camera module composition
3.1 Lens: The art of optics
The lens is the first part of the camera module to come into contact with light, and its structure is complex and precise. Modern lenses are usually composed of multiple lenses, which are arranged according to a specific optical design to eliminate aberrations and improve image quality. According to different uses and performance, lenses can be divided into wide-angle lenses, telephoto lenses, macro lenses and other types.
Key parameters of the lens:
Focal length: The distance from the center of the lens to the imaging plane determines the viewing angle and magnification of the captured image.
Aperture: A device that controls the amount of light entering the lens. The larger the aperture, the more light enters and the shallower the depth of field.
Distortion: Image deformation caused by lens design or manufacturing defects needs to be corrected by software algorithms.
Advanced lens technology
Optical image stabilization: Through built-in sensors and motors, it detects and compensates for slight jitters during handheld shooting to improve imaging stability.
Multiple aspherical lenses: reduce aberration and distortion, improve image quality.
Coating technology: reduce light reflection and scattering, improve light transmittance and color reproduction.
3.2 Image sensor: the magician who captures light
The basic structure of the image sensor:
The image sensor is the core component of the camera module, responsible for converting light signals into electrical signals. CMOS and CCD are two common types of image sensors, among which CMOS dominates portable devices such as smartphones due to its advantages such as low power consumption and high integration.
Key features of image sensors:
Resolution: The number of pixels on the sensor determines the fineness of the image.
Pixel size: The area of a single pixel affects the light receiving ability and signal-to-noise ratio.
Dynamic range: The difference range between the brightest and darkest light that the sensor can capture.
Advanced sensor technology:
Back-illuminated CMOS: Move the circuit layer to the back of the sensor to improve light utilization and image quality.
Stacked CMOS: Separate the signal processing circuit from the pixel array to improve data transmission speed and signal processing efficiency.
HDR technology: Improve the details of bright and dark parts of the picture through multi-frame synthesis or single-frame optimization algorithm.
3.3. Voice Coil Motor (VCM): The Behind-the-Scenes Hero of Autofocus
Working Principle of VCM:
Voice coil motor is a key component for realizing autofocus function in camera module. It uses the principle of electromagnetic induction to drive the lens to move by the force of the energized coil in the magnetic field, thereby adjusting the focal length to achieve focus.
Performance indicators of VCM:
Focus speed: response time from infinity to the closest focus distance.
Focus accuracy: the accuracy of the focus position, which affects the image clarity.
Noise control: mechanical noise and electromagnetic noise generated by VCM during operation.
Advanced VCM technology:
Closed-loop focus system: The focus position is detected by the sensor and fed back to the VCM in real time for adjustment, improving the focus accuracy and speed.
Dual VCM design: Simultaneously control the forward and backward movement and tilt angle of the lens to achieve more complex focus and anti-shake functions.
3.4, infrared filter and FPCB: indispensable auxiliary components
Infrared filter
The infrared filter is used to filter out the infrared component in the light to ensure that the light received by the image sensor is consistent with what the human eye sees. It is particularly important in surveillance cameras that switch between day and night, and can avoid the color cast problem caused by infrared light at night.
3.5 Bracket
As the name suggests, it is used for support. It is mainly used to load VCM and lens, and will place photosensitive components such as sensor and driver IC in the inner cavity.
Among them, Driver IC is related to the front voice coil motor VCM. The current size is controlled by Driver IC, thereby controlling the position of VCM.
3.6 Flexible printed circuit board
As the “neural network” in the camera module, FPCB is responsible for connecting various components and transmitting data. Its good flexibility and stability can ensure the reliability and stability of data transmission. At the same time, the design of FPCB also needs to consider issues such as electromagnetic shielding and heat dissipation.
As the functions of cameras become more and more complex and the amount of data to be transmitted increases, FPCB design becomes more and more important. It can effectively reduce the noise problem in the signal and improve the transmission efficiency of the image.
As one of the core components of digital imaging technology, the camera module has a complex and precise structure. With the coordinated work of key components such as lenses, sensors, voice coil motors, infrared filters and FPCB, the camera module can bring us a clear, delicate and realistic image experience. With the continuous advancement and innovation of technology, the performance of camera modules will continue to improve, bringing us more surprises and possibilities. I hope this article can help and inspire you to gain a deeper understanding of the camera module structure.
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