Why light from TV’s display doesn’t project it’s image on surfaces like projector?
In: Physics
Short answer: projectors shoot light in straight lines, tv screens shoot light in all directions.
Each pixel of a tv screen sends its color of light in every direction at once, like a light bulb. You can see the image when you look at the tv screen because light from each pixel is hitting your eye from exactly one direction, but nearby surfaces like a wall are being hit by light from each of the pixels individually. When the light is reflected off the wall and hits your eye, the different colors of light are scattered across the wall and the image has been destroyed. If you have a tv on in a dark room, you’ll still be able to see the intensity and the overall color of whatever is playing reflected on the surroundings, but you won’t be able to make out any detail.
I don’t know exactly how a modern projector works, but somehow they shine light from each pixel in only one direction. This allows the image to be cast onto a surface without any blurring.
All that’s needed for a projected image is for the light hitting each point on the viewing surface to be coming from only one direction. If you placed a barrier in your room with a tiny hole in it and had a very bright tv, you could create a projection on the wall opposite the tv by forcing the light from each pixel to pass through the hole- but because the light from pixels on the bottom of the screen will have to slant upwards to reach the hold, the image will be upside-down!
This phenomenon is called a camera obscura and they are SO. COOL. Google it and look at pictures!
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