Dead pixels often show up as white or black dots on your projector screen. Why exactly are they there?
It can be very disturbing to notice these spots during projection. They take up space on the screen where color should be.
Pixels are important for good quality projection. Dead pixels are often a result of internal issues.
In this article, we will explain pixels in detail. We also describe 4 causes of dead pixels in projectors.
- What Are Pixels And What Do They Do?
- Dead Pixels: How Do They Look?
- What Causes Dead Pixels on the Projector?
What Are Pixels And What Do They Do?
We have mentioned the word ‘pixels’ multiple times already. For the purpose of clarity, we will now explain it.
Pixels are the tiniest unit of any digital image. The combination of thousands or millions of pixels form an image.
The higher the amount of pixels a projector is capable of displaying, the sharper its image quality.
How Do We Know How Many Pixels a Projector Has?
The product of a projector’s native resolution will give the pixel number.
- WXGA (1280 × 800) = 1,024,000 pixels
- XGA (1024 × 768) = 786,000 pixels
- VGA (800 × 600) = 480,000 pixels
The resolution number describes the number of pixels on a horizontal and vertical line.
The (1280 × 800) of WXGA means there are 1,280 horizontal and 800 vertical pixels.
Where are the Pixels Found in Projectors?
Pixels are found in the microdisplay chips.
Most projectors use microdisplay technologies. They may be LCD panels, DMD chips or LCoS chips.
These microdisplay units constitute a fixed amount of pixels. They contain micro mirrors which reflect or deflect light rays.
The micromirrors are referred to as pixels.
DLP projectors have about 2 million micromirrors on one chip. Some DLP projectors have up to 3 chips.
This is why they have crisper images. They also tend to develop more dead pixels as time goes by.
Dead Pixels: How Do They Look?
How do you actually know that a pixel in your projector is dead?
First of all, let’s describe what a projector pixel does. A pixel (micromirror) is either in an on or off position.
In the on position, it reflects colored light to create images. When off, it deflects the light to create dark/grey shades.
The combination of all the light reflected or deflected by all the pixels make up a full image.
When a pixel dies, it no longer reflects light. It shows up as a permanent black dot on the screen due to a lack of light in that spot.
You may see a colored spot; red, blue, green or white, instead of black. Colored spots mean that a pixel is stuck.
When a pixel is stuck, it is permanently in an on position. The spot it creates is bright and unchanging.
What Causes Dead Pixels on the Projector?
There are a number of reasons your projectors pixels could be dying. These reasons include:
- Manufacturing faults
- Dust and dirt
- Current overload
While it may sound far-fetched, many devices come with manufacturing faults. It is common for errors to be made during assembly.
Sometimes, the error is in the internal settings. The manufacturers may have failed to set the display chips properly.
These errors can result in faulty pixels. You start to notice black spots on your screen shortly after purchasing.
With time, these dead pixels increase in number. They cause a reduction in the quality of the projector’s display.
Dust and Dirt
Projectors often come protected against dust and dirt. They have filters that should keep out dust and dirt.
However, some amount of dirt gets in sometimes. It may even be from those accumulated by the filter.
This dust can get into the projector and cause spots on the lamp or lens. These spots show up on the screen.
The good thing is that these spots are not exactly dead pixels. They can be removed by opening and cleaning the projector.
However, dust may block the air vents. Projector fans circulate air through the device using those vents.
When the vents are blocked, cool air cannot get into the projector. Overheating occurs at this point.
Overheating can damage the microdisplay chips in a projector. This damages pixels and breaks down images.
Microdisplay chips are highly sensitive to heat. DLP chips are the most sensitive.
For this reason, it is common to find dead pixels while using a DLP projector.
The environment may contribute to overheating. If a projector is placed in a poorly ventilated area, it can overheat.
When pixels get too hot, they may experience electrical failure. The circuit controlling their on/off positions may be damaged.
We mentioned earlier that overheating can result in electrical failure. Well, an overload of electric current can do the same.
The higher the supply of current to the projector, the hotter the projector’s insides become.
The vents and cooling fans are near useless in these cases. At a point, the chips may start to burn.
The burned pixels show up as dark spots on the screen.
All the factors described above can cause a microdisplay chip to malfunction. When it does, pixels may die or get stuck.
Blunt force to the DLP chip or LCD panel may cause pixels to get damaged too. However, the position of the chips in a projector shields them from such occurrences.
Is there a solution to this problem? Can one fix a projector with dead pixels?
I’m afraid the answer is no. Dead pixels can simply not be resurrected.
1. How to prevent dead pixels?
Now that you know what can contribute to dead pixels, it is fairly easy to prevent it.
Keep projectors properly ventilated to prevent overheating.
When you notice dust and dirt beginning to build up, clean your projector filter.
Use your projector in the right way, as specified in the user manual.
When there is a surge of current, disconnect it from the power source and wait till the current stabilizes.
2. Do dead pixels go away?
What can one do about dead pixels? Do the spots fade away with time?
No, they don’t. Dead pixels are an indication of a weakening chip. It is only bound to get worse with time.
The process cannot be reversed. However, you can change your projectors microdisplay chip by yourself.
This is the only way around it. A stuck DMD chip still has some hope of recovery.
If it’s a fault from manufacturers, get it replaced. Try to test any device you purchase, as soon as you can manage.
Still curious? Read: How do You Fix a White Dot on The Projector Screen.
3. Why does my projector have black dots?
If you notice black dots on your screen during projection, you probably have a technical issue on your hands.
Projector pixels show up as black dots on the screen when they die.
The pixels responsible for reflecting light onto that part of the screen no longer function.
The possible reasons for this occurrence include manufacturing defects and damage to your microdisplay chip caused by heat.
When this starts happening, you cannot stop it. The only way out is to change the DLP chip or LCD panel.
You may not have black or white spots on your screen now. However, this information is still important.
With DLP projectors, pixel damage is almost inevitable. It is just a matter of ‘When?’
Dead pixels are unattractive on projector screens. They leave displayed images incomplete and unappealing.