The rainbow effect has definitely become quite rare in modern DLP projectors – but if you’re looking for it, it’s pretty easy to spot nevertheless. It’s a stroboscopic effect where you see flashes of primary colors.
This happens when our eye-brain coordination deals with spinning color filter wheels and high-speed motion on the screen.
Mainly, single-chip DLP projectors have a prominent rainbow effect.
What is the rainbow effect on a DLP projector?
The rainbow effect on a DLP projector is caused by the light that is reflected by the optical lens and then passes through the dichroic filter again. This results in an output image with colored pixels.
The color of the pixel depends on the wavelength of the light source, which is either white or blue. The longer wavelength produces a green pixel, while the shorter wavelength produces red or orange.
What causes the rainbow effect on a projector?
The rainbow effect is a phenomenon that occurs when a DLP projector sends out light in all directions, instead of just one direction. The result is a spectrum of colors, which appears as a rainbow.
The reason for the rainbow effect is that DLP projectors use mirrors to reflect the light from the lamp onto the screen. Some of the light will be reflected back into the lamp and some of it will be sent out into the room.
This can produce an uneven distribution of light and depending on how much light is being reflected back into the lamp, this can result in some areas getting more light than others.
This leads to an uneven distribution of colors on your screen.
To sum up, the most common cause of this effect is an uneven distribution of light over an image, which causes it to be reflected off the surface of a lens, creating the illusion of color when none is actually present.
The color distribution can also occur because there are not enough LEDs in an LED projector to provide sufficient illumination, resulting in uneven illumination across your screen.
This causes areas where there are no LEDs to appear dark while other areas appear bright with no color at all. In order for this type of rainbow effect to occur, you need to make sure that each pixel on your screen is receiving enough illumination so it appears white against black backgrounds.
Do LED projectors have the rainbow effect?
The color wheel can wear out and become inaccurate over time (this happens very quickly). Also, the indexing mechanism in some projectors can get dirty and cause unevenness in your image quality.
Both these can lead to the rainbow effect in LED projectors.
The rainbow effect occurs when there are multiple points of illumination at different brightness levels within an image. This creates a visual effect that appears to have multiple colors being emitted from a single point source.
Do Laser projectors have the rainbow effect?
Yes, laser projectors do have the rainbow effect – but it’s fairly rare.
The rainbow effect is commonly found in projectors with RGBW or YUV inputs, which allow the user to select from multiple sources for each pixel on the screen. You may also see this effect when using a computer monitor with “fringed” pixels (such as an LCD screen).
Why do some people see the rainbow effect?
This phenomenon occurs because of the way our eyes perceive light: they are more sensitive to certain frequencies than others.
For example, if you look at anything with a very high contrast ratio between light and dark areas, then you will notice that these areas appear to jump out from behind other parts of an image or object.
With DLP projectors, if there are two pixels on opposite sides of the screen and they are not at full brightness but just slightly off from each other (one being darker than the other), then some people may see a rainbow effect appear when they turn on their projector.
Do all DLP projectors have the rainbow effect?
No, not all DLP projectors have this effect,
In fact, it’s becoming an increasingly rare occurrence. Most modern DLP projectors will not have the rainbow effect.
So, if you’ve been struggling with it for a while, then your best bet is probably to buy a recent model from a reputable manufacturer.
Is there any way to eliminate or minimize the rainbow effect?
The color can be removed by using a dichroic filter that absorbs certain wavelengths of light and reflects others in order to reduce the rainbow effect.
The most common type of dichroic filter is made from glass plates coated with metal oxides, such as aluminum oxide (Al) or zirconium oxide (ZrO).
These plates are placed behind each color wheel segment (RGB) on a DLP projector’s screen, which filters out some wavelengths while letting other wavelengths pass through unhindered toward your eyes.
How do I know if my projector color wheel is bad?
The color wheel that is used to produce the red, green, and blue colors for an image or video can also be used to create different hues when mixing different colors together.
This is what causes the rainbow effect and it can be seen with DLP projectors as well as LCD projectors.
There’s no intrinsic property to look out for when it comes to determining the accuracy or reliability of your projector’s color wheel. You’ll need to look for visual glitches and errors – the rainbow effect being one of them – to be sure of anything.
Conclusion
The rainbow effect is a color distortion that occurs when the light from a projector is unevenly distributed over the image on the screen.
The phenomenon can be caused by several factors, including the type of lamp used in the projector and its intensity, as well as whether or not the projector has a glass or plastic lens.
This visual effect is a result of the combination of red, green, and blue light in a single beam. It is common with DLP projectors. So, DLP projectors indeed still have the rainbow effect – especially single-chip ones. But it’s becoming rarer every passing year with the advent of better technology and manufacturing processes.