Quote:
Originally Posted by Cinisajoy
Postive, negative and ground or is ground only used in houses?
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Electrical charge and electrical current (or potential) are different beasts. And in house wiring we use alternating current, which is even more beastly until you bother to study it. Tesla is the man, in that department...
Electric charge is determined by the relative proportion of extra or missing electrons. In electronic components, missing electrons are often referred to as "holes" because they are locations in the semiconductive crystalline structure where an electron is missing and another electron can fall into place. Semiconductors have permanent electric charges duffused into them in the form of atoms of an element that has extra or missing electrons (relative to silicon) in their outer orbits.
An eink particle with a permanent positive charge is lacking electrons and therefore repelled from a positive field and attracted to a negative electric field, whereas negatively charge particles (of opposite color) are repelled from a negative field and attracted to a positive field
Though I have not read this anywhere, it makes sense to me: If eink particles are dielectric, it would be possible to give them a permanenet electric charge using the same method as forming electric capacitor peranenet charges -- melt and resolidify them while held in an electric field. For example, stack a layer of black plastic on white plastic (with waxed paper between then) between metallic sheets, put an electric charge across the metallic sheets, then melt and cool them. After separating the black and white layers, powder them, mix them together in oil (i.e. eink), and encapsulate the eink in beads to prevent it from all flowing the the bottom of your eink screen when you hold your ebook vertically. You need a grid of electrodes over both sides (front and back), and the front side must be made of conductive transparent metal (typically ITO - indium tin oxide).
To get the electric fields where they belong at each pixel, you need to minimize external connections using transistors at each pixel position, forming a charge-coupled bucket-brigade shift register. Though I think our eink displays do gray values using pusle timing, a charge-coupled device could also allow analog values to be shifted to each pixel position. Perhaps such methods are used in the new color eink?
Electrophoresis causes the charged particles to migrate through the oil inside the beads, at a speed dependent on oil viscosity (and temperature). To get grayscale, it is necessary to control how long the field is applied, and the temperature must be measured to do that. That is why the waveform tables contain multiple waveforms (timing values) for various gray values at various temperatures.
And for many eink controllers, the waveform tables also contain the firmware that runs in the eink controller. Anybody want to write an eink virus?
Okay, the "
little professor" has finished his lecture.