What is the production process of mobile phone camera?

As a new shooting function of mobile phone, the built-in digital camera has the same function as the low-end (65438+ million-1.3 million pixels) digital camera we usually see. Compared with traditional cameras, traditional cameras use "film" as the carrier of recording information, while the "film" of digital cameras is the imaging photosensitive device and the heart of digital shooting. The photoreceptor is the core of the camera and the most critical technology.

According to the structure, cameras are divided into built-in and external, but the basic principle is the same.

According to the photosensitive devices used, there are CCD and CMOS:

CCD (Charge Coupled Device) is made of highly sensitive semiconductor material, which can convert light into charge and then into digital signal through A/D converter chip. After the digital signal is compressed, it is stored in the flash memory of the camera or the built-in hard disk card, so the data can be easily transmitted to the computer, and with the help of computer processing means, the image can be modified as needed and imagined. CCD is composed of many photosensitive units. When the surface of CCD is illuminated by light, each photosensitive unit will reflect the charge on the module, and the signals generated by all photosensitive units will be superimposed together to form a complete picture. Just like the negative film of a traditional camera, it is a photosensitive system and a circuit device for sensing light. You can think of it as tiny sensing particles scattered behind an optical lens. When light and images are projected onto the CCD surface through the lens, the CCD will generate current and convert the sensed content into digital data for storage. The more CCD pixels, the larger the size of a single pixel, and the clearer the collected image. Therefore, although the number of CCD is not the only key to determine the image quality, we can still regard it as one of the important standards of camera grade. At present, most scanners, video cameras and digital cameras are equipped with CCD.

After 35 years of development, the general shape and working mode of CCD have been finalized. CCD is mainly composed of a mosaic grid, a condenser lens and an electronic circuit matrix at the bottom. At present, companies capable of producing CCD are Sony, Philips, Kodak, Panasonic, Fuji and Sharp, most of which are Japanese manufacturers.

Cmos (complementary et al-oxide semiconductor), like CCD, is a semiconductor that can record light changes in digital cameras. The manufacturing process of CMOS is no different from that of general computer chips, mainly using semiconductors made of silicon and germanium, so that semiconductors with N (charged) and P (charged) energy levels coexist on CMOS, and the currents generated by these two complementary effects can be recorded and interpreted as images by processing chips. However, the disadvantage of CMOS is that it is too prone to clutter, mainly because the early design makes CMOS overheat when dealing with rapidly changing images, because the current changes too frequently.

The advantages and disadvantages of CCD and CMOS respectively, we can compare the main differences between them from the technical point of view:

Information is read in different ways. The charge information stored in CCD sensor needs to be read after being transferred bit by bit under the control of synchronous signal. Charge information transmission and reading output need to cooperate with clock control circuit and three different power supplies, and the whole circuit is complicated. CMOS sensor directly generates current (or voltage) signal after photoelectric conversion, and the signal reading is very simple.

The speed is different. CCD sensor needs to output information bit by bit under the control of synchronous clock, which is slow. CMOS sensor can take out electrical signals while collecting optical signals, and can also process the image information of each unit at the same time, which is much faster than CCD.

Power supply and power consumption. CCD sensor charge couplers mostly need three groups of power supplies, which consumes a lot of power. CMOS sensor only needs one power supply, and its power consumption is very small, only 1/8 to110 of CCD charge coupler. CMOS photoelectric sensor has great advantages in energy saving.

Imaging quality. The manufacturing technology of CCD sensor started earlier and the technology is relatively mature. PN combined with silicon dioxide isolation layer is used to isolate noise, and the imaging quality is better than that of CMOS sensor. Because of the high integration of CMOS sensor, the photoelectric sensor is very close to the circuit, and the optical, electrical and magnetic interference between them is serious, and the noise has a great influence on the image quality.

At the same resolution, CMOS is cheaper than CCD, but the image quality produced by CMOS devices is lower than CCD. So far, most consumer-grade and high-end digital cameras on the market use CCD as sensors; CMOS sensors are used as low-end products in some cameras. Whether there is a CCD sensor has once become one of the standards for people to judge the grade of digital cameras. Because the manufacturing cost and power consumption of CMOS are much lower than that of CCD, many mobile phone manufacturers use CMOS lenses. Now most mobile phones on the market use CMOS cameras, and a few also use CCD cameras.

Continuous shooting principle

The continuous shooting function is to capture the shooting opportunity by saving data transmission time. Continuous shooting mode can take multiple photos in a short time by loading the data into the high-speed memory (cache) inside the digital camera instead of transferring the data to the memory card. Because digital cameras have to go through photoelectric conversion, A/D conversion and media recording, both conversion and recording take time, especially recording takes time. So the continuous shooting speed of all digital cameras is not very fast.

Continuous shooting is usually calculated in frames, just like film. Each frame represents a picture. The more frames can be captured per second, the faster the continuous shooting function. At present, the fastest continuous shooting speed in digital cameras is 7 frames per second, and it takes several seconds for continuous shooting to continue shooting after 3 seconds. Of course, continuous shooting speed is an index that photographers and sports photographers must pay attention to, but it can be ignored in ordinary photography occasions. Generally speaking, the resolution and quality of photos taken by continuous shooting will be reduced. Some digital cameras can choose the continuous shooting function. When shooting small-resolution photos, the continuous shooting speed can be accelerated; On the contrary, the continuous shooting speed of photos with high resolution will be relatively slow.

Through the continuous snapshot mode, you can shoot continuously by pressing the button, and record the continuous action vividly.

Principle of optical zoom and digital zoom

Optical zoom is achieved by changing the positions of lens, object and focus. When the image plane moves in the horizontal direction, as shown below, the visual field and focal length will change, and the farther scenery will become clearer, making people feel that the object is moving forward.

Obviously, there are two ways to change the perspective. One is to change the focal length of the lens. In photography, this is optical zoom. The focal length of the zoom lens is changed by changing the relative position of the lens. The other is to change the size of the imaging plane, that is, the diagonal length of the imaging plane. In today's digital photography, this is called digital zoom. In fact, digital zoom does not change the focal length of the lens, but changes the viewing angle by changing the diagonal of the imaging plane, thus producing an effect equivalent to the focal length change of the lens.

Therefore, we can see that some digital cameras with long lenses have more room for moving the internal lens and photoreceptor, so the zoom factor is also larger. We see that some ultra-thin digital cameras on the market generally have no optical zoom function, because the roots in the fuselage are not allowed to move the photosensitive devices, while Sony F828, Fuji S7000 and other "long lens" digital cameras have optical zoom functions as high as 5 or 6 times.

Digital Zoom, also known as digital zoom, enlarges the area of each pixel in the picture through the processor in the digital camera, so as to achieve the purpose of enlargement. This technology is like enlarging the area of a picture with image processing software, but the program is executed in a digital camera. Some pixels on the original image sensor are enlarged by interpolation, and the pixels on the image sensor are enlarged to the whole picture by interpolation algorithm.

Different from optical zoom, digital zoom is the change of the vertical direction of the photosensitive device, which gives people a zoom effect. The smaller the area on the photosensitive device, the user can only see part of the scene visually. However, because the focal length has not changed, the picture quality is worse than normal.

Through digital zoom, the shot scene is enlarged, but its definition will be reduced to some extent, so the practical significance of digital zoom is not great. Because too large digital zoom will seriously damage the image, and sometimes even because the magnification is too high, it is impossible to distinguish the shot picture.

Four tips for mobile phone shooting?

The pixels of mobile phones are generally not high. But if you think about it a little, you can still take good photos with your mobile phone.

Rule 1: Use the "trisection" to write. In the actual photographic composition, the scene of the subject is slightly staggered from the center, so we should pay attention to the echo of the subject and other objects. The main scene of the photo taken in this way is bright and prominent, and it will not be blurred.

The second side light can highlight the texture best. Generally speaking, the side light can better highlight the texture of the object, so we should make full use of the side light. When backlighting or side backlighting, you can consider blocking with objects. If it is impossible, cover the camera with your hand to reduce the influence of backlight. Attention should also be paid to shooting under strong light. Never shoot in the glare with the lens of your mobile phone.

Rule 3: Don't turn the phone immediately after pressing the button. The phenomenon of mobile phone photo delay is generally obvious, and this delay will be more obvious if you use a mobile phone with an external camera to take pictures. If your hands shake at the moment you press the shutter, the photos you take will be blurred. So, remember not to turn the camera immediately after pressing the shoot button.

Rule 4: Try not to shoot with digital zoom. If you use digital zoom to take pictures, it will weaken the clarity of the image, and the effect is not as good as not using digital zoom. For example, a photo with a resolution of 640×480 taken with digital zoom may have an actual resolution of only 320×240. When viewed on a computer, the image either becomes smaller or blurred.

This article should be helpful to you!