If you unplug the cable of the set-top box, that is, the cable of the TV, the set-top box can still start automatically, indicating that there is something wrong with the cable or the interface of the TV.
Due to the busy work and the rise of mobile phones, we seldom use TV sets. However, there is a new house in the home decoration, and the TV is an essential household appliance. When buying TV, some friends are always confused and don't know where to start. Here's how to choose a TV set in many ways.
Image quality is always the first demand of TV sets, and it is not difficult to understand the image quality: it is the degree of picture restoration. So from which aspect should we judge the quality of TV? Basically, resolution, contrast, color and dynamics are the most basic criteria for judging the quality of a TV set.
Resolution: On the premise of the same size and the same film source, the higher the screen resolution of the TV, the clearer the picture. At present, the mainstream of TV market is 4k TV, or uhd TV. The 4k TV of UHDTV standard refers to 3840×2 160 pixels. 2020 is the first year of commercialization of 8k TV. The resolution of 8k 7680×4320 is four times that of 4k TV. As far as resolution is concerned, it is worthy of attention.
At this time, some people may say, do I need to buy a 4k TV? Because the current digital TV signals are mainly 720p and 1080p, and I hardly watch the 4k film source.
If that's your opinion, if you insist on buying a 1080p TV, you can only choose a low-end TV with a maximum of 45 inches and a very average picture quality, or your budget is insufficient, but at present, the cheapest 4k TV of mainstream brands on the market is less than 2000 yuan. For newly renovated or newly renovated friends, it is still recommended to choose mainstream 4k TV.
So what size TV set is best for us to buy? Take the mainstream 4k TV of domestic first-line brands as an example. The following figure is the reference standard for screen size and optimal viewing distance.
Reference distance calculated according to the angle between 30 and 40 in the visual range. Referring to this set of charts can ensure that the picture fills the whole field of vision and get the best immersive viewing experience. However, for most friends, budget is one of the biggest factors that restrict size selection. In this regard, there are the following suggestions.
1, 55 inches to 65 inches is the size with the largest shipment, the richest products and the highest cost performance. If you just watch TV programs and don't pursue the viewing experience, you can choose a 55-inch to 65-inch TV set according to the icon above.
2. If you watch high-definition movies and ball games on TV and pay attention to the viewing experience, the bigger the screen, the better. The recommended size is about 75 inches, because 75 inches is the upper limit of the size that can maintain a relatively high cost performance on the market at present.
3. In the case that the picture quality gap is acceptable, even if it exceeds the budget, priority should be given to the larger TV, because the viewing experience of the big screen is more obvious.
Contrast: The contrast of TV pictures generally refers to static contrast. Is the brightness ratio between white in the brightest area and black in the darkest area of the screen under the same test frame. More accurately, the brightness range is one of the biggest gaps between the display screen and the real scene. High contrast is the basis of accurately restoring light and dark scenes.
It should be noted that for organic light-emitting diode TV, contrast has no reference significance. Because the OLED pixels can be turned off individually, the brightness is zero and the contrast is close to infinity in theory. This also shows that the maximum brightness of Oled is not as valuable as high-end led TV.
Color gamut and color depth: At present, the color gamut of TV sets in the market is a subset of CIE color space, and several color gamut standards have been defined in the home appliance market, such as NTSC, Rec.709, DCI p3, sRGB, Adobe RGB, Rec.2020 and so on. Among them, Rec.2020 is the color gamut standard of UHD TV.
Wide color gamut: Wide color gamut is the basis of good color expression. For TV supporting HDR, color gamut effect is one of the main factors that affect HDR effect. The color gamut coverage of the same type of TV with different grades is quite different. According to the different color gamut standards adopted by different manufacturers, the color gamut coverage under the same standard state is generally QLed-OLed-Led.
Color depth, also called color number, is the number of colors that combine brightness and chroma. The biggest difference between color and color gamut is that the color depth takes into account the influence of gray scale. At present, for TV, the color gamut depends on the spectral characteristics of backlight and the matching degree of backlight, which has nothing to do with the panel, but the color depth is a parameter of the panel. If the color depth of a screen is nbit, then the corresponding gray level is 2 n, and the number of colors that can be represented is (2 n) 3. Set the color depth to eight times for each increment of 1 bit. Low-end TV sets generally use 8brt panel (256 gray scale), and high-end TV sets generally use 10bit panel (1024 gray scale). The higher the connection level, the more natural the color transition.
Hello, everyone, I'm a home appliance repairman. We will update this chapter about the choice of TV set here, and we will continue to update how to choose TV set in the next chapter.