How to Build an LCD Projector
The crisp, high-quality image output of an LCD projector is simply hard to beat for the price. Plasma or LCD flat screens may offer a crisper image, but they simply can't provide the same screen real estate that a projector can. 100" to 150" images are possible with inexpensive or home built systems.
Given that high quality commercial projectors are thousands of dollars, some do-it-yourselfers with basic knowledge of electronics choose to take this project on to save money.
A high-quality projector can be built in your own garage for only a few hundred dollars and many hours of your time. Be aware that this is not an easy project, and it will likely take several straight days of work before the projector is finished.
This LCD projector will be built inside a plywood housing, and will consist of a regular LCD screen that is displaying the desired video from a television or DVD player's video output. The LCD screen will be stripped down, so that a very bright halogen bulb is lighting the screen instead of the standard LED bulb. A fresnel lens will be used to evenly distribute the light. The final image will then be projected through a regular LCD projector's lens and onto a screen, producing a crisp image like a commercial projector.
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Things You'll Need
- Plywood
- Flat black spray paint
- LCD screen
- Halogen bulb in housing
- Fresnel lens
- LCD projection lens
- 2 120mm Computer case fans
- 12 volt AC adapter
Instructions
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1
Do a rough test fit of your components to determine a size for the outer box, which will be built out of plywood. The box should have enough room to house all of the components, plus adequate dead space to allow for proper ventilation of the heat produced by the halogen bulb. Before actually building the box, it helps to make a mock-up using cardboard and masking tape, to ensure the components fit properly.
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2
Cut the six sides for your housing, which will ultimately be rectangular in shape. Assemble all but the top cover of the box using wood screws, and paint the inside flat black to help absorb stray light. For a more finished, commercial look, sand the outside panels using progressively finer grit paper until it is perfectly smooth to the touch, then paint the outside of the panels as well.
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3
Disassemble your LCD screen. Any type of screen will work, but you may wish to use a higher resolution screen to ensure high quality video. Remove the casing and the backlight, so that the LCD panel itself is open for your halogen bulb to light it up. Make sure any circuit boards or cords are out of the way so that they won't cast a shadow across the screen while the system is running.
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Mount the LCD screen to the casing. Metal "L" shaped brackets work great to hold the screen upright. You can also craft your own mounting system using wooden supports that are screwed into place on either side. The mounting system should ensure the screen stays in place even during movement or transportation, and it should not get in the way of the visible video or light path in any way. This is a great time to secure wires and cables out of the way using zip ties.
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5
Behind the screen, install the halogen light so that it is aimed perfectly at the back of the LCD panel. Screw it into place to ensure it doesn't move around, and drill a small hole for the power cord to exit the enclosure. Place a fresnel lens directly behind the LCD panel to evenly distribute the light across the entire panel, and glue it into place to keep it from moving around.
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Install the two 120mm computer case fans near the center of the box. They should be placed on opposite ends from each other, with one acting as an intake fan, and the other acting as an exhaust. The 12v AC adapter can be used to power the fans, and the wiring can be run out the same hole as the halogen's power cord. Hot glue works great to keep wires from moving around.
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Drill a hole for the LCD projector lens, located directly across from the LCD screen. An actual projector lens with a manual focusing mechanism can be purchased from parts stores for around $10. After installing the lens, the LCD screen itself may require fine-tuning to ensure the picture is lined up perfectly straight. If needed, an additional fresnel lens is sometimes placed between the LCD to ensure even light disbursement.
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Test the projector. Using a projection screen, or a plain white wall, test the distance of the projector. The further away from the screen the projector is, the larger the image will be, but the dimmer it will be as well. Once the desired size has been found, the manual focus on the projection lens can be used to dial in the picture to the perfect clarity.
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Tips & Warnings
For a true movie-theater experience, mount the projector on the ceiling of the room. The LCD's built in keystone and skew adjustments can be used to dial the picture in perfectly.
Never let the projector run unattended, and always keep a functioning fire extinguisher on hand.
Resources
- Photo Credit viewsonic.com
