lcd

339 Articles

Bill Hammack Explains How LED Backlit LCD Monitors Work

March 17, 2011 by 14 Comments

We had a basic understanding of how LCD monitors worked, and you may too. But the thing is, [Bill Hammack] doesn’t just explain the basics. Since he’s the Engineer Guy he explains the engineering principles behind how LED backlit LCD screens operate. But he does it in a way that everyone can understand.

After the break we’ve embedded his five-minute video. In it you’ll see him strip down a monitor to the back plate and then build it up piece-by-piece. We enjoyed his discussion of how the diffuser panels work together to even out and distribute the light. Theses are made of several layers and, although we knew they were there from working with salvaged LCD screens, we never knew quite what they were doing. He also covers how each liquid crystal cell works along with polarizing sheets to either block or allow light passage. And he’ll bring it on home by show how thin-film transistors in each subpixel of the screen work to multiplex the display, just like we did with that pumpkin back in October.

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LCD Twofer

March 17, 2011 by 13 Comments

Inexpensive character LCDs are a popular choice for outputting data on many projects. Easily controlled , often back lit, and compact. If you have not found a reason to get one yet, here are a couple.

First up is a Programmable digital timer switch. Based around a PIC15f628A micro controller this handy little device allows you to set both on and off times to switch (light duty) devices through its relay. A standard 16×2 LCD , piezo buzzer, and 4 push buttons offer the device’s I / O. The four buttons are assigned to on / off time, select, enter, and start / stop making it easy for anyone to use. All this and sporting a clean perf-board layout which often goes out the window when using jumper wire.

Next for the AVR crowd is a LCD Name badge. Powered by a Attiny 2313 and using another 16×2 LCD, this time in blue this large, but functional name badge is ready to give out all the information people need on you while boasting your nerd credit.

Source and schematics are available for both, and yes we know these little gadgets are not exactly earth shattering so that is why we invite you to share your LCD projects on quite possibly the most awesome forum ever, the Hack A Day forums, we even have a little spot setup just for project logs.

But first join us after the break for a couple quick videos.

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DIY Digital Pinball Console Plays Hundreds Of Games

March 14, 2011 by 23 Comments

pinball_console

Pinball machines, while likely considered pretty retro technology by most, are still a fun and engaging way to waste a little time. The problem with pinball machines is that they take up a lot of space, making the hobby of collecting them pretty prohibitive unless you have tons of spare room in your house.

[tbarklay] loves pinball machines but doesn’t have to room for an elaborate collection. Rather than purchase one machine, he opted to build his own pinball table that can be used to play any number of games. He repurposed an old PC to power his table, connecting it to a 24″ LCD panel for the main display board. A custom cabinet was built to contain the large LCD panel as well as the computer. A 19″ LCD screen was mounted on top of the cabinet to serve as the backglass display. A set of arcade buttons were also added to the console to provide realistic paddle control.

While we don’t have a video of his particular table in action, check out this video we found of  a pinball machine that uses the same setup.

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Video Projector From An Old Single-slide Unit

February 24, 2011 by 21 Comments

Here’s a video projector that [Matt] hacked together. He needed a small and inexpensive solution to use with his R2D2 build. As you can see in the video after the break, it has no problem playing back the Princess’ distress call. But even if R2D2 is not one of the droids you’re looking for, we think this can be useful in other ways. One use that pops into mind is for projector-based Halloween displays.

As with past projector hacks, all you really need to pull this off is a light source, an LCD screen on which you can playback video, and a lens to focus the light onto a screen. Usually the LCD is the most expensive part of the project and building an enclosure to the correct dimensions can be a bit difficult. [Matt’s] solution was to use an MP4 knockoff media player. The rest of the setup is a ’50s era slide projector. The screen from the media player is about the same size as a single film slide, so he removed the screen from the case and put it where the slides go.

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Interfacing An Arduino With A TFT LCD

February 21, 2011 by 8 Comments

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Seven-segment displays and monochrome LCDs are fine for most projects, but some things simply look better in color. [John] over at the Little Bird Electronics blog recently wrote up a tutorial demonstrating the use of a TFT LCD panel with an Arduino. The specific panel he chose was a 4D Systems 1.44” TFT LCD that happened to feature a dedicated graphics processor, which should allow for some fantastic visuals when used to its fullest potential.

The LCD takes its commands over a serial interface, making it a simple five-wire display solution for your projects. The display can be programmed manually by sending hex commands over the serial interface, but there are also some user-developed libraries available that will allow you to use the majority of the most popular functions without the learning curve. One thing to note is that the LCD must be flashed with a particular flavor of firmware before it can communicate over the serial interface, a process for which [John] provides a walk through.

The LCD panel can be used with any Arduino-compatible board, so it can be useful in a whole host of projects.

Stick around to see a simple demo of the board in use.

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Driving A Salvaged LCD

February 10, 2011 by 21 Comments

[bill2009] wanted to reuse some common seven segment LCDs, but the question was how to drive them. Armed with a couple application notes from [Microchip] and [Atmel], an oscilloscope and an Arduino, he has made a proof of concept which shows its not super hard to drive those little reflective LCDs that so many devices have.

First finding out that these things are indeed multiplexed, he went on to what is needed to drive them, which is about +-2 volts difference from the backplane, next up was to find a donor, which he found readily at Staples, in the form of a “clocky” style run away alarm clock.

After poking around watching what signals do to the different segments on the LCD he whipped up a little circuit to control the display from the Arduino. The positive and negative voltages the segments require are made possible by the use of a set of pull down resistors, and switching pin modes on the micro controller.

These small type segmented LCDs are everywhere, and being able to use them is a big bonus.

Laptop LCD Reused In Beagleboard Project

February 7, 2011 by 15 Comments

This daughterboard lets [Matt Evans] drive a laptop LCD using a Beagleboard. Apparently the Beagleboard gained a VGA header when it moved to revision C but [Matt’s] working with revision B4 which is why he had to do all of that ninja soldering with the blue wires. The driver board itself is a thing of beauty, hosting a DS90C363 LVDS serialiser as well as some buffer chips that handle level conversion for it. He’s also included an ATmega48 so that he has some options for future improvements.

The LCD is mounted in a custom acrylic case, with Beagleboard and driver board taped to the back of it. There’s RS232 and a USB hub which opens up the possibility of using a WiFi dongle for communications. So far he doesn’t have much functionality other than displaying images on the screen but there is some talk about using a touchpad for control. We’d love to see a touchscreen overlay, transforming the build into a proper ARM-based tablet.