LCD monitors are relatively hard to manufacture. Every little dot (pixel) formed by 3 sub pixels (red, green and blue) has to be placed very accurately in the appropriate place. One little mistake made during the process may disable one or more (sub)pixels. Top manufacturers use only perfect LCD panels, without any problems, and sell the rest to less-known manufacturers that will install them in different categories of cheap monitors, clearly specifying in user manuals that they don’t have perfect picture quality.
Sadly not all manufacturers respect this logic. Some try to sell all panels as new, grade A+ products, without notifying the customer. Quietly they publish specifications about quality on their site (usually hidden from the eyes of unexperienced shoppers), admitting that a few defective pixels are acceptable, and the monitor cannot be returned under warranty for this specific reason.
This is when you should use a program to test lcd monitors. LCD’s are really easy to test. Basically you need three (red, green and blue) pictures that fill out the screen. Any defective pixel will appear and you notice it instantly.
A defective pixel can have many different colors. The less annoying ones are simply black spots, instead of the three colors there’s just black. This is the only case when you may consider keeping the monitor despite 1-2 such dead pixels.
The worst defective pixel is constantly lit in bright white color, incredibly frustrating. Unless you set the contrast to maximum, nothing on the screen will have a similar color so that you could tolerate it. Theoretically a white pixel shouldn’t bother you when working with black on white text, but in any other case it doesn’t fit in with the rest of the pixels. The best solution is to return it ASAP. In most countries any IT&C product can be returned in 15-30 days from purchase and the entire price will be refunded or the product will be replaced with a new one, your choice.
Partially dead pixels (with dead sub pixels) are irritating too, but they don’t show up in every situation. For example if the red part is dead (black) it won’t show up if the displayed color doesn’t need the red component, or it shows up a little if a little red is needed, but it’s less noticeable.
There are two more types of panel defects. One is when some foreign particle gets sealed between the panel’s sheets. A piece of hair or dust, and the monitor cannot be classified as A+ anymore.
The other common defect – slightly bent panel – may occur even after shipping, while it’s sitting in storage. The monitor enclosure may bend due to improper shipping or storage conditions, bending the display panel too, so the back lighting of the screen will be permanently damaged. Bigger spots on the panel will appear darker or brighter. This defect can be noticed right in the store by supplying the screen with a 100% white image, and looking at it from slightly different angles.
In conclusion, it’s best to use any basic program to test lcd monitors before purchase, even a photo viewer with white, red, green and blue jpegs is enough. Also keep in mind that you may return the LCD in 15-30 days from purchase (depending on your country’s legislation), without any specific reason, you should get a full refund or a new product.
