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Introduction to the Camera Module (CCM)

Time of issue:2021-12-10

　　The camera’s close-up camera module—whose full name is “camera compact module,” and which we’ll abbreviate here as CCM—is a crucial electronic component for image capture. Let’s start with a close-up shot; there are all sorts of different designs, though the one I was debugging recently wasn’t very pretty.

　　How a camera works and the functions of each component in a camera

　　To fully understand something, you need to dig deeper. If it’s code, we’ll analyze it step by step; if it’s a module, we’ll break it down to see exactly how it works.

(1) Working Principle: Light rays from an object, focused by a lens, are converted into electrical signals via a CMOS or CCD integrated circuit. These electrical signals are then processed by an internal Image Signal Processor (ISP) to generate digital image signals, which are subsequently sent to a Digital Signal Processor (DSP) for further processing and conversion into standard image formats such as RGB or YUV.

(2) A CCM comprises four major components: the lens, the sensor, the flexible printed circuit (FPC), and the image processing chip (DSP). The key components that determine the quality of a camera are: the lens, the image processing chip (DSP), and the sensor. The core technologies of CCM include optical design technology, aspheric lens manufacturing technology, and optical coating technology.

　　The lens is the soul of a camera. It plays a crucial role in determining the quality of the image captured. By leveraging the principle of refraction through lenses, light rays from the scene pass through the lens and converge onto the focal plane, forming a sharp image that is then recorded by a photosensitive sensor—either a CMOS or CCD device. Lens manufacturers are primarily concentrated in Taiwan, Japan, and South Korea. As an industry with high optical technology content, lenses have relatively high barriers to entry. Well-known companies in this field include Fujifilm Precision, Konica Minolta, Largan Precision, and Enplas.

　　The sensor is the core module of the CCM. Currently, two types are widely used: one is the widely adopted CCD (charge-coupled device) component, and the other is the CMOS (complementary metal-oxide-semiconductor) device.

　　The charge-coupled device (CCD) image sensor is made from a highly photosensitive semiconductor material that converts light into electrical charges, which are then converted into digital signals by an analog-to-digital converter chip. A CCD consists of numerous photosensitive elements, typically measured in millions of pixels. When the surface of a CCD is exposed to light, each photosensitive element generates an electrical charge that is recorded by its corresponding component. The combined signals from all these photosensitive elements together form a complete image. CCD sensor modules are dominated by Japanese manufacturers, with over 90% of the global market share controlled by Japanese companies led by Sony, Panasonic, and Sharp.

　　Complementary Metal-Oxide Semiconductor (CMOS) is a type of semiconductor primarily made from two elements—silicon and germanium—allowing both n-type (negatively charged) and p-type (positively charged) semiconductors to coexist on the same CMOS chip. The currents generated by these complementary effects can be captured and interpreted by the chip as images. CMOS sensors are predominantly led by companies based in the United States, Taiwan, and South Korea. Major manufacturers include Omnivision and Agilent from the U.S., Ruidao, Novatek, and Taevis from Taiwan, and Samsung and Hyundai from South Korea.

　　The image-processing chip (DSP) is an essential component of the CCM. Its function is to promptly and efficiently transmit the data acquired by the image sensor to the central processor and to refresh the image sensor itself. Therefore, the quality of the DSP chip directly affects the image quality—for example, color saturation and sharpness.

　　FPC flexible circuit board (flexible PCB): commonly referred to as a "soft board" or "flexible circuit board," it connects chips and mobile phones, serving the function of transmitting electrical signals.

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