How does an LCD screen have such few connection points and still produce over 2 million pixels?
In: Engineering
Basically, there’s this sort of chip that converts the data. Think of it like Google Translate, but instead of English to Spanish, it’s binary data to actual address lines.
Adding on, a display is basically a giant, perfectly square neighborhood. Each row and column is a street, and each pixel is like a three-home townhouse. Whenever a signal is sent, it’s like a mailman delivering something to that precise town house. Depending on the signal, or “mail”, the individual homes in the townhouse light up.
I, uh, hope that’s enough.
Do you mean the HDMI cable connection to the monitor/TV or the actual electronic connections of the LCD screen?
Basically, an LCD screen does not draw all 2 millions pixels at once but rather block per block. The time it takes for the whole screen to be redrawn is defined by the refresh rate. Most LCD displays use a technology called Active Matrix to handle the huge numbers of pixels in a cost effective way. Only a small group of pixels is addressed (connected) at one time and it can switch between different groups when it needs to do updates. An active matrix of size m*n pixels means that you only need m+n connectors to address those pixels.
Are you asking about the connection to the monitor (e.g. HDMI) or the connection inside the monitor from its electronics board to the panel?
The answers are completely different.
For HDMI/DP/USB/VGA/etc. it is quite simple. Time. The data for all pixels are sent one after another but very quickly. So for 2 million pixels and 60 fps, the signal for each pixel has just 1/120,000,000 of a second to be transmitted. That’s quite fast, which is the reason display cables can only be a certain length before the signal cannot make it anymore without active repeaters.
This is also the reason why connector standards change every so often. More pixels, more information per pixel, and more fps means that the old connectors cannot transfer the data fast enough.
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For the panels: First, there are chips directly on the panel. Those are fed by the electronics board, and their primary purpose is to reduce the amount of cable needed by employing the same “one after another” technique as the display cable. Just at a lower level.
Then (for larger panels) the panel is wired internally in blocks. The same signal wires go to many pixels but there’s a second set of wires that switch which of those blocks reacts to the signal. Within those segments, the pixels are arranged in a X-Y grid pattern. This reduces the wires needed (one for each column and one for each row), but makes it so that only one column (or row) at a time can be sent a signal. So, for example, the data for one column goes onto the wires for the row, and then the column wire turns on, allowing those pixels to receive the data. All the other columns don’t have power, so they don’t change.
Same way you can write a letter with Morse code, you just send one pixel at a time but really really fast.
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