Summary analysis and detailed explanation of charge-coupled device CCD application

The application of CCD is mainly based on its three unique effects-storage effect, transfer effect and photoelectric effect. It is currently mainly used in information processing, information storage and imaging, etc. three aspects.

1, CCD information processing

This is the CCD application field that is being developed vigorously, such as CCD delay line, CCD filtering, frequency compression and communication decoding in radar communication. One of the most successful applications currently is the CCD delay line. This is a delay line that directly uses the signal charge to transmit and store in the surface potential well of the CCD to complete the delay function.

The adjusted delay line is a circuit that reproduces the original input signal as accurately as possible after a certain delay time. Because the input signal of the CCD has to be transmitted by the potential well before it can be sampled and output at the output end, the CCD itself is a natural delay line. It can be used as a delay line for analog quantity transmission or as a delay line for digital quantity transmission. The maximum delay time of the CCD delay line is determined by the clock pulse frequency and the number of transmission electrodes. Therefore, this electronically controlled delay line can be used as a fixed delay or as a variable delay. Charge coupled device CCD. The CCD delay line has the characteristics of small size, large delay range, low power consumption, high signal-to-noise ratio and low cost. However, the transfer efficiency decreases in the VHF range, and the linear response is not good. Therefore, it is mainly used in video and high-frequency range, such as TV, telephone delay line, color TV delay line, high-fidelity audio reverb, language fidelity long delay, etc.

2, CCD information storage

CCD itself has the function of storing information charge, so an ordinary CCD plus output and input circuit is a shift register. Charge coupled device CCD. If the CCD shift register is connected to the next CCD shift register with the regeneration circuit, the output terminal of the last stage is connected to the input terminal of the first stage to form a circular memory, as shown in Figure 4-34.

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The other form is COD serial memory. It is regenerated by a combination of serial shift memory, parallel shift register and transmission electrode array.

It has also been used in random access memory. In addition, it can be combined with non-volatile memory to make the main read memory and so on. Due to the high integration and low cost of CCD, it can be used as a large-capacity memory, and will eventually replace the drum and magnetic disk as the external memory of the computer.

3, CCD camera

Solid imaging is one of the three application areas of CCD. It is a camera made by using the photoelectric effect of CCD, which can be divided into two structures: one-dimensional linear array and two-dimensional surface array.

As mentioned earlier, if light shines on the back of a thin silicon substrate or enters the silicon substrate through a transparent electrode and insulating layer, electrons proportional to the intensity of the light will be generated. -Hole pair, charge coupled device CCD. The electrons are collected in the potential well. After a certain period of time, the pattern of light intensity can form a pattern corresponding to the information charge in the semiconductor. Then, the information of the entire frame is sequentially moved to the readout storage area by the clock pulse, and then the Under the action of another clock pulse, the whole moves downward to enter the readout register and output through the diode.

Compared with the traditional electron beam vacuum camera tube, the CCD camera does not require external mechanical scanning or electronic scanning. It is small in size, light in weight, and low in voltage (generally Less than 20V) Large dynamic range, strong maneuverability, can work in harsh environments, no need for strong lighting, etc.

The CCD image sensor is used in occasions: visible light, low light (star light), infrared, laser, etc. CCD can be used to make high-resolution image fax machines and standard TV resolution and frequency compatible black and white and color TV cameras, fax phones, various industrial surveillance camera systems, missile remote control guides; charge coupled device CCD .

In terms of shimmer, it can be made at 10^{-4-4 sup>Night vision weapon sights that work under lux illumination, starlight guidance devices for spacecraft, etc. In short, CCD cameras are widely used in civil and military applications.}

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