Composition of mobile phone camera module
June 6, 2023
The mobile phone module mainly consists of a lens, an image sensor, and an IF interface. It is mainly used as an interface for camera phone picture and video input, and it is mounted on the phone. After the lens generates image data, the burden of processing and analyzing the image data is all handed over to the mobile phone processor. Figure 1 is the functional block diagram of the mobile phone image module hardware. It consists of a lens unit and an image sensor.
Figure 1 Explosion diagram of mobile phone module
Figure 2 below is an exploded diagram of the hardware of the mobile phone camera module, which breaks down the various components of a mobile phone camera module in detail. The most important are the lens group, filter, and image sensor.
The lens group in the mobile phone camera module is composed of several lenses. Its composition structure has glass lens (glass) or plastic lens (plastic). Relatively speaking, the quality of the camera with glass lens is better, and the imaging effect will be better than that of plastic lens. Therefore, glass lenses are more expensive. In general, the lens structure of the camera is divided into: 1P, 2P, 1G1P, 1G2P, 2G2P, 4G, etc., and the price continues to rise as the number of lenses increases. Most of the camera products on the market now generally use plastic lenses or half-plastic half-glass lenses (ie: 1P, 2P, 1G1P, 1G2P, etc.) to reduce costs.
IR cut filter:
Infrared filter, camera module filter, the scientific name is "optical low-pass filter" (OLPF). Its main function is to filter out infrared rays. The image sensor used in the camera module is an electronic component, so it can also sense infrared rays. The image sensor converts the infrared light into an electrical signal, and as a result, the image processing chip cannot calculate the correct color. Therefore, the camera module needs to add a filter to filter out infrared light. But at the same time interference must be prevented. Blue glass can "absorb" filtered infrared light. But it cannot prevent the interference of light, and prevent the light entering the lens from interfering with each other. The physical polarization characteristics of quartz crystals retain direct light, reflect off oblique light, and avoid mutual interference of light. So there is a "two-piece" filter with a piece of blue glass and a piece of quartz. The blue glass in the lens filters out infrared light, while the quartz plate removes interference.
Image sensor (SENSOR):
The main function of the image sensor is to complete the conversion of photoelectric signals. The image sensor is the most important link in all camera modules, which affects the image quality the most. The degree of understanding of the image sensor also directly determines the design and evaluates the quality of the camera module. The photosensitive elements used in mainstream cameras on the market are mainly CCD and CMOS. The active pixel CMOS image sensor is equipped with a signal amplifier and noise control components on each image sensing pixel, which greatly reduces the influence of noise and improves the image sensing quality.
According to the number of pixels of the image sensor, the data format, etc., the image sensor will generate a large amount of data, which needs to be transmitted to the corresponding image processor. Therefore, as the amount of data continues to increase, the integration technology continues to improve. The graphics interface is also constantly being upgraded.
MDDI: (Mobile Display Digital Interface)  is a high-speed serial interface for mobile phones. MDDI is an interface standard for portable devices that use video signals specified by the video equipment industry group VESA (Video Electronics Standards Association). The transfer rate supports up to 3.2Gbps. There are 6 data lines, because the number of data lines is correspondingly reduced, so the problem of noise interference can be effectively reduced. Same as the MIPI standard, in addition to standard data streams, MDDI can also support user-defined data types.
DVP: (Digital Video Port) Digital Video Port. This interface is a parallel interface, which mainly supports the second camera.
Parallel Interface: parallel interface. That is, how many pin video signal interfaces the processor has, and how many pin interfaces the video module provides. The advantage is that the speed is faster, and the disadvantage is that there are more pins.
CSI-1, CSI-2: Camera Serial Interfaces. It is a video interface standard developed by the camera working group in the MIPI Alliance, that is, the Mobile Industry Processor Interface (MIPI) Alliance. The MIPI standard is subdivided into two types of serial and parallel, and the serial is divided into two types of CSI-1 and CSI-2.
CCP1, CCP2: intensive camera ports. SMIA makes detailed regulations on camera modules. High-speed serial interfaces CCP1, CCP2 are defined based on "Dense Camera Port". The interface can effectively ensure the data transmission between the camera module and the computer or mobile phone processor. The transmission speed of CCP1 reaches 208Mbps, and the transmission speed of CCP2 reaches 640Mbps.