The day’s getting closer when you might be able to unplug your full-size computer screen, roll it up and stick it into your pocket. Today’s liquid crystal displays, or LCDs — used in laptops, watches and cell phones — are sandwiched between two rigid pieces of glass. But researchers at Royal Philips Electronics have devised a way of making them by just painting the raw materials onto almost any kind of surface: walls, sheets of plastic — or even clothing.