DIY Smartphone Projector (for watching movies)

Summary

In this DIY tutorial, Matt shows how to create a smartphone projector using simple materials like cardboard, a magnifying glass, and a bi-convex lens. The project involves building a sturdy base, adding a focusing mechanism with dowels and straws, and securing a mirror at a 45-degree angle. A crucial part of the design is creating bellows to block light leakage, ensuring a sharp, clear image. This projector solves common issues like image flipping and poor focus, making it great for movie watching or even gaming. The guide also includes fun ideas like tracing paper projections and stencil designs for added creativity.

Takeaways

• 😀 A DIY smartphone projector can be made using simple materials like a shoebox, a magnifying glass, and cardboard to demonstrate the basic concept.
• 😀 One major issue with basic smartphone projectors is the image inversion, which can make it hard to read text or play games without adjusting settings.
• 😀 The project suggests building a more advanced, functional projector with a vintage design, utilizing craft cardboard and other accessible materials.
• 😀 A clear and effective focusing system for the projector is created by using dowels and straws, allowing the user to adjust the focus and height.
• 😀 A small mirror, placed at a 45-degree angle, helps reflect the phone’s light, contributing to a sharper, more usable image.
• 😀 A platform for the phone is made from cardboard with a hole cut for the phone’s screen, mounted on the dowels to control the height and focus.
• 😀 The lens used in the projector should have a focal length between 200-300mm, with a bi-convex lens being the preferred choice for brightness and clarity.
• 😀 To prevent light leakage from the sides, a bellows system made of paper is used around the projector, ensuring a more vivid image by blocking stray light.
• 😀 The bellows are made using printable templates that are folded into a concertina style, which can be painted black to block light effectively.
• 😀 The finished projector design allows for easy adjustments, with the phone being placed on top and the image sharpness adjusted by moving the phone up or down.
• 😀 The design also offers fun alternatives, such as using tracing paper for stencil projections or turning the system into an inverted camera-like projection.

Q & A

What is the main idea behind this DIY smartphone projector?

The main idea is to create a vintage-inspired, functional smartphone projector using simple materials like cardboard, a magnifying glass, dowels, and a mirror. The design addresses common issues with other smartphone projectors, such as image inversion and light leakage.

Why is the image upside down in the basic shoebox projector design?

The magnifying glass inverts the image, which results in the phone's display being flipped upside down. This can be somewhat corrected by locking the phone's rotation, but it still remains horizontally flipped, which makes text unreadable.

How do you improve the focusing system for the projector?

The focusing system is improved by using dowels and straws to create adjustable supports for the phone. A small mirror is also added at a 45-degree angle inside the box to reflect light through the lens, allowing for better focus and image clarity.

What type of lens is recommended for the projector, and why?

A bi-convex lens with a 300mm focal length is recommended. This type of lens is similar to the ones found in magnifying glasses and provides a sharp, focused image. A larger lens may result in a dimmer image, while a smaller lens may not capture enough light.

Why is it important to use a lens with a larger focal length, and what happens if the focal length is too small?

A larger focal length lens helps produce a brighter image because it focuses light over a shorter distance. If the focal length is too small, the image will be dimmer because the light is spread out more, which could make the projected image hard to see in darker settings.

What role does the mirror play in the projector design?

The mirror reflects the light from the phone's screen at a 45-degree angle, redirecting it through the lens to project the image onto the wall. This setup ensures that the image is upright and enhances the overall quality of the projection.

How can you prevent light leakage around the lens in the projector?

To prevent light leakage, a bellow system made from folded paper is added around the lens. This system mimics an old camera's bellows, blocking unwanted light and ensuring that the projected image is clear and sharp without any washed-out areas.

What is the purpose of the bellow system, and how is it created?

The bellow system is designed to block any excess light from escaping around the lens, which would otherwise reduce image quality. It's created using paper templates that are folded into a concertina shape, painted black to block light, and then attached to the projector with double-sided tape.

What additional fun feature can you add to the projector for creative effects?

One fun feature is replacing the phone with tracing paper, which inverts the projection and creates a 'camera-like' effect, showing a projected image of the real world. You can also try stencil projections by shining light through cutout shapes to create interesting patterns on the wall.

How does the phone's placement affect the image sharpness in the projector?

The phone's placement on the projector can be adjusted up or down to focus the image. This is done by moving the phone closer or farther from the mirror until the image becomes sharp. The projector needs to be used in a completely dark room, and the phone’s screen should be set to maximum brightness for optimal results.