Hi,
I’ve been keen to make displays using eink technology. Been doing a little research and the concept is pretty simple and should be achievable in the home.
From what I’ve been able to gather, they consist of a front conductive transparent plane covering a solution of oil and white and black particles suspended in little capsules or cells to stop them sloshing about. Behind that is a conductor pattern.
In the book readers showing arbitary dot matrix displays they also sometimes have transistors to switch on an XY pattern…but simpler devices like on the Esquire magazine display just use patterned PCBs (flexible in the case of the magazine display).
The principle seems to be to apply a positive or negative voltage on the conductors relative to the front conductor. The particles have an inbuilt surface charge, so depending on the voltage polarity they migrate either to the front or back of the display, hence showing either black or white.
I’ve managed to separate out the front conductor from old passive LCD screens…so that bit is done. You carefully heat the seal between the LCD glass plates with a torch. Use eye protection, as sometimes it can crack. I haven’t tried baking them in an oven yet…but they method for getting a conductive glass plate should work as well. You also need to shave off the glue seal where they filled the glass sandwich with liquid crystal solution to provide some pressure release.
Printing a PCB is easy, I dont need high resolution, seven segment or bar graphs are fine for me. Also the drive electronics need not be high voltage, nor fast. From dissections of the Esquire device they are using around 12-15V apparently.
Putting the white/black particle mix into cells making a thin pattern on ridges ontop the PCB…possibly by using resin and pressing a patterned surface ontop, then peeling it away.
So the problem is picking suitable white and black particles with an inherent surface charge that will migrate back and forth depending on the applied electric field. I’ve tried printer toner and titanium dioxide…but they seem to have a neutral charge so don’t go anywhere, printers have to apply the charge separately using a corona wire which bears this theory out.
Any ideas on commonly available powders that have a suitable inherent surface charge? Chemistry is beyond me. I’ve looked at the eink patents…but they’re all gobbledygook to me.
It’d be great if the eink manufactures sold the epaper films separately but their economic model seems focused on supplying the drive electronics and pre-built displays…not the raw material itself (which is no doubt cheap).
Phil