Hi, I'm currently designing a screen for a 7" touch screen.
I bought a 7" video screen like those used on the headrests of cars, it only has an AV video connection
I fitted the touch screen to it and had to get a VGA to AV converter.
After all the fuss of setting it up, small writing is blurred so all graphics need to be a lot larger so you can read them.
This is because of the low resolution of AV video screens.
In hindsight, I should have looked for a screen that has a VGA input built in and then you will get clearer smaller graphics.