Inventor: 1924, British Baird invented the most primitive TV set, which transmitted images by telex. American RCA 1939 introduced the world's first black-and-white TV set, 1953 formulated the national color TV standard, and 1954 introduced RCA color TV set. Because the radio frequency signal will be mixed with some interference signals in the process of air transmission, and will be attenuated with the increase of transmission distance, after receiving the weak radio frequency TV signal from cable or antenna (RF-in), the TV set must first demodulate, amplify, mix and detect it through the tuner to filter out the high-frequency carrier components, so as to obtain the composite full TV signal in PAL, NTSC or SECAM formats. The audio signal and video signal are separated from the full TV signal. The audio signal is processed by the audio circuit and sent to the speaker for output. The video signal is amplified by video, and the luminance and chrominance signals are separated to obtain YC component signals. Finally, YC component signal is converted into YUV, and then converted into RGB component signal, which is sent to CRT for display. In the whole TV signal, because the chrominance signal occupies the bandwidth of 2.6MHz, some electronic circuits of the TV directly intercept the low luminance signal of about 3MHz when separating the luminance and chrominance signals. In this case, although the screen of the TV set can reach the horizontal resolution of about 500 lines, the actual horizontal resolution of the TV signal input from the antenna is only about 260 lines. In addition, the signal intensity of different channels is different, and the resolution of the image reflected on the screen is also different. Judging from the current popular trend of domestic color TV market, new color TV products with high definition, large screen and high image quality have become the mainstream of the next generation color TV development. Among them, plasma and liquid crystal occupy the dominant position in the market and become the most powerful opponents for the dominant position in the next generation TV market. So, what are their advantages and disadvantages? How do consumers make wise choices according to their own needs? From the appearance, the plasma TV has a thin body, a wide screen and a clear picture. Thin and light is a major feature of plasma TV. A 60-70 inch TV is only six or seven centimeters thick; In addition, it has a wide viewing angle (up to 180 degrees); Secondly, from the technical point of view, plasma TV adopts digital display mode, which is beneficial to improve the definition of imaging. Now plasma TV can convert analog signals into digital signals; Moreover, its driving voltage is better than the previous TV, which can be used to watch TV, VCD, DVD, digital TV and receive satellite TV on the Internet, making it the first choice for home theaters. In addition, plasma TV has a rich and easy-to-use interface, which can be connected to multimedia signal sources such as personal computers and electronic game machines. But at present, the technology of plasma TV is not perfect, and there are still some defects in some aspects. If the power consumption is large, usually as high as 300W or more, it is a big power consumer in household appliances; There is no competitive advantage in resolution, contrast and resolution of panel image quality; The heat dissipation problem is still difficult to solve. At present, LCD TV has certain advantages over plasma TV. LCD TV has become another main product in the high-end color TV market because of its ultra-thin, clear, environmental protection and energy saving characteristics. LCD TV has no flicker and radiation, which reduces people's visual fatigue. It has rich interfaces, which can connect audio and video devices such as computers and DVDs, and can well meet the needs of digital TV broadcasting in the future. LCD TV is more colorful than plasma TV, and its power consumption is only 1/3 of that of plasma TV. The life span of LCD TV is about 60,000 hours, which is twice that of plasma. The characteristics of high brightness and high contrast of the new generation LCD TV are also better than plasma. An excellent LCD TV must have a good performance in brightness, contrast, resolution and viewing angle. Like plasma color TV, LCD TV has no flicker, thin thickness and light weight, but it is not as good as plasma in terms of large screen. In the large-screen high-end TV market, plasma has inherent advantages in technology and price, so there is a saying that "plasma is bigger and LCD is smaller". 30 inches has always been considered as the dividing line between LCD and plasma TV. Liquid crystal is an organic compound with regular molecular arrangement between solid and liquid. Under the action of different electric fields, liquid crystal molecules will rotate 90 degrees according to the rules, resulting in the difference of light transmittance, thus resulting in the difference of light and dark under the power switch. According to this principle, each pixel can be controlled to form a desired image. LCD TV is made by this principle, and it is technically difficult to make LCD TV bigger. But in recent years, with the development of science and technology, LCD TV has also begun to develop in the direction of big screen. Shortly after the launch of the world's largest 46-inch LCD TV, the 50-inch LCD TV recently exhibited in the United States set a new record. Who won more in terms of price? Generally speaking, under the same specifications and models, the price of large-screen LCD is generally higher than that of plasma, while the price of small-screen LCD is lower. In the popular 30-to 34-inch TV, the price of LCD screen drops faster than that of plasma screen. In the west, LCD TV has penetrated into the kitchens, living rooms and bathrooms of many families, which fully shows the advantages of ultra-thin, wall-hung, flat and energy-saving. According to the customer service staff of Suning Appliance Shenzhen Store, LCD TV is suitable for close-up viewing and families with small rooms because of its small screen. Because of the large screen, plasma is usually placed in a relatively large space, which is suitable for long-distance viewing.
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