Many of my projects start the same way: find ‘broken’ technology equipment thrown away by wasteful IT Services at UChicago. This macbook didn’t know what broken meant until I tore into it. It was a great opportunity to learn a bunch about LCDs and how the display works, but found some other gems in this guy along the way. It came without the battery, HDD, RAM and with a broken optical bay. Here is what it looked like after the keyboard was removed.
I found this awesome chip I really liked inside, you can see it above on the left hand side in the middle. It’s sitting on top of the motherboard with a little mount. Looks like maybe a wifi card; the mount reminds me of a miniature PCI card from a desktop. What it actually is doesn’t interest me, just trying to logic out what it could be. Also there are three wires with fancy gold connectors on the top, looks like they don’t go into the motherboard but rather out towards the display. Antenna maybe? Or high voltage from whatever powers the display? Will see more of this later. Here is a the chip:
And the gold connectors, look like the connectors we used at the lab wiring semiconductors for HV possibly.
Oddities aside, what I really went into this poor little computer for was the LCD. Since I’m charged with making a touch screen LCD this summer for the Uncommon Fund, I figured I should start small (and broken) to get my hands dirty. Here is the back of the lid behind the LCD, which has been dislodged from the back panel and lowered down (i.e. the rear of the LCD/backlight setup is on the bottom).
As it turned out, the LCD itself was very boring: sandwiched between two pieces of glass there was nothing to see. The interesting part, unexpectedly, was the backlight. The basic concept (as far as I can gather) is to pipe in light from two edges
The backlight is comprised of 4 layers: a reflective back sheet, a thin acrylic sheet, a diffuser and two very interesting layers which I’ve pictured below.
As you can see, these two layers take light from the center and split it so it appears to come from both the left and right (the other layer is the opposite, splitting light up and down. I was confused about why this would be in an LCD where you always want to be looking directly at the screen, not a two mirrored images. But then I realized I had it backwards: these take light from the edge and double it to the other side. This is because there are only LED’s on two sides of the acrylic, so these sheets when layered on top of each other (below) make light look like it is coming evenly from all 4 edges quadrants. This makes the uneven light from the LED’s on two edges look like even 4 side lighting