Have you ever experienced this: You bought a "high-end" LCD screen, but when you installed it, the picture quality was dull, the viewing angle was off and you couldn't see clearly, and the brightness was not half of what was advertised? When you went to the manufacturer, they said, "The parameters meet the standards, it's a selection issue." That was a one-liner that shut you down. The LCD screen purchase was scammed. 90% of the time, it's not because of bad luck, but because the parameters weren't understood. Today, I will explain 5 pitfalls that insiders won't mention in one go. After reading this article, you will be more professional than 80% of the purchasers in the market. 1. Resolution, don't just ask "how many times by how many times" 1920×1080, you must have seen this parameter. But do you know? For the same 1080P, a 10-inch screen and a 21-inch screen have completely different display effects. The key is not to look at "how many K", but to look at PPI (pixel density). 2. Resolution, don't just ask "how many times by how many times" 10.1 inches 1080P → PPI ≈ 218, no graininess at normal viewing distance 21.5 inches 1080P → PPI ≈ 102, visible grains at close range Don't ask "is it several K", but ask: "For this size and this resolution, what is the PPI?" Screens with a PPI lower than 120 are not suitable for close viewing. The size and PPI must be matched to see, asking less questions can easily lead to losses. 2. Brightness, typical values and minimum values, a big difference The specification reads "500cd/m²", but when you measure it, it's less than 300. It's not that the manufacturer is exaggerating, it's because you didn't understand the testing standard. 3. Brightness, typical values and minimum values, a big difference There are two types of brightness in the industry: Typical value (Typ): Laboratory ideal conditions, the data looks good, but you can't get it. Minimum value (Min): The lower limit that the manufacturer guarantees for batch production, closer to the actual goods you receive. Low-price suppliers like to use the Typ value to boast, when purchasing, just ask: "What is the minimum value Min of brightness?" In strong light environments (outdoor advertising machines, sunlight direct exposure scenarios), the actual measurement is 350 and the typical value is 500, the difference is the life of the product. Ask for the Min value, don't believe the typical value. 3. Contrast, static and dynamic, a factor of two "1000:1 contrast" sounds very professional. But there's a trick in the industry called dynamic contrast, the numbers can be marked as 5000:1, 10000:1, but it's actually not very useful, it only appears instantly when the picture's brightness changes rapidly, you can't feel it in daily use. 4. Contrast, static and dynamic, a factor of two The only valuable one is: static contrast. A static contrast lower than 800:1 has obvious gray-scale loss in color reproduction scenarios (designing, video editing), the picture becomes dull and muffled. Industry rules: Those who like to mark dynamic contrast often have poor static contrast. Only recognize static contrast, 800:1 is the threshold. Also, in outdoor or high-brightness environments, contrast affects visibility more than brightness, you can ask about surface treatment (anti-glare vs mirror). 5. Viewing angle, marked 178°, the actual comfortable range is only 150°~160° 178° wide viewing angle, almost every company writes this. But have you tried: from the side, the color becomes white and dim, like there's a layer of fog? The key is that "178°" is the limit angle when contrast decays to 10:1. That is to say, at 178°, the contrast of the picture is only one-tenth, the color has seriously distorted. The actual comfortable viewing angle you can see is only 150°~160°. 5. Viewing angle, marked 178°, the actual comfortable range is only 150°~160° Don't be fooled by numbers. When purchasing, directly ask about the panel type: IPS > VA > TN. If the screen needs to be viewed by multiple people or from the side (such as information display screens or advertising machines), IPS panels should not be chosen. When considering the panel type, do not just focus on the stated viewing angle. V. Response Time - The smaller the number, the better? Not necessarily 5ms, 3ms, 1ms, does a smaller number mean greater performance? Not necessarily. The key is what your screen is used for. 6. Response time, the smaller the number, the better? Not necessarily Office / Industrial Displays: 5 to 15 ms is sufficient. Game Displays: 5 ms or less is preferred, the lower the better. Medical Monitoring Screens: Response time is not crucial, color consistency and gray scale are the core. If you are an industrial purchaser, blindly pursuing an ultra-low response time of 1 ms may result in paying 20% to 30% more for a performance that you won't actually use. Moreover, these "fast LCD" panels often compromise on color or viewing angle, and may also lead to a longer supply cycle. Decide on the scenario first, then select the parameters. Don't be led by numbers. 7.5 points are where LCD screen purchases are most vulnerable. The above 5 points are the most vulnerable areas in LCD screen purchases. It's not that the suppliers are deceiving you, but that you haven't asked the right questions. Before the next purchase, make sure to understand these 5 things: Resolution: Is the PPI sufficient? Brightness: What is the minimum value? Contrast: Static or dynamic? Viewing angle: What type of panel is it? Response time: For which scenario? After asking these 5 questions, you are already more professional than most purchasers. The best way to avoid being cheated is to turn yourself into an expert.