This reminds me of a couple of toy drawing tablets I had as a kid in the early 1980's. - My first one was like a faux wood plastic picture frame with a soft thick layer of clear polythene drawing surface, under that was a black oil gel like liquid which hid a multi coloured plastic surface beneath. You draw/scribe on it with a stylus which thinned the black gel to reveal the colours under it. - A special squeegee was used to erase the etching, similar to screen-printing ink squeegee method. It eventually burst on a corner and the black gunk slowly oozed out. My second drawing tablet was more simple than that. - It was a frame with layer of clear (drawing surface), light grey (the graphic material) and glossy black (graphic medium colour) sheets of plastic. When drawn on the light grey plastic would adhere to the black gloss which resulted in dark grey etchings that resembled graphite pencil marks. - To erase the image a sliding blade between the grey and black layers would wipe across the screen unsticking the etching to a blank surface again. - These mini tablets are an electronic version of the tablets I mentioned above.
The bipolar AC waveform is re polarising the LCD crystal material, thereby creating a very polarised to light transparancy. As the surface(s) of the LCD structure ate also polarised sheets, by coresponding polarisation can create a blocking or passing of polarised light, similar to the way Polaroid sun glasses when turned can blank or show any LCD screen. Well once the LCD crystal is twisted into a polarising form, the crystal now looks black. If now pressure is applied the crustal looses its uniform orientation created by the AC stimulation, and it no longer passes only polarised light, but now allows multiple orienrations of light polarised light through, making a clear appearance at the pressured region. Reapply the AC will repolarise the LCD orientation and blank the dispkay area. In normal LCD displays a pattern of electrodes on the enclosing 'glass' sheets applies similar orientation while the electrodes are AC driven, creating blank on clear or opposite clear on black appearance of the many segment patterns of the display whether clear or black at the AC driven segments is then dependant on polarising filter sheet orientation. Either back reflective or backlit etc determines the appearance. BW or colour is just a bit more complexity and for colour relevant colour filters. Of course this sketch device is just one large polarosing segment that has pressure destroying the polarising effect, and a very simple AC drive, voltage stepup circuit to work its magic. Good show. Sadly it appears the sharp bending has likely moved fone mesh of seperator material that holds the surfaces at extremely fine distance, allowing the LCD materisl to work. Now even possbly putting both surfaces into contact with little or no crystal material lft. Anyhow destroying the thickness control of the LCD at the lower corner, prevents function, and possibly even breaking the seal, and progressive destruction of the LCD material, and the failed area may be growing over time. Already the lower corner blank patch was larger than initial reactivation or possbly further failure while reassembling.
Ha! The fellow German has the best explanation... that's awesome! Do you know any neat trick like a combination with a circular polarizer (similar to the quantum eraser experiment maybe) or a specific light source to do something exciting with those scribbling boards?
@@f.d.6667 have not considered other uses. 8 just f3lt a little simplified explanation might be info4mative to other followers of 5his channel. Hope it is of use to others to understand this technology. There is more detail and complexities, but this should cover the matter at simply overview.
Nice job! ... I was buying a few of those as well, hoping to be able to hack them into something "useful" ... had no luck so far AND haven't across anybody who did: the LCD is "transflective" and appears to be of the "cholesteric" (chiral) bistable type. The square wave is (apparently) used to flop the crystals back to their non-translucent state... the best Idea for a totally useless device (display) I could come up with was a "mechanical" input (x/y driven by steppers or servos): think automated etch-a-sketch...
When I bought one years ago, it was listed as e-ink instead of lcd. Never owned a kindle, but I had an e-ink watch (Pebble). The watch lasted ages between charge since the battery was only used to update the display.
My 2 cents about function. Being that LCD's are made of rod shaped molecules, deforming it (them) would change their orientation, allowing light to pass through the screen (I guess there's a reflector behind it). Powering the screen [could] re-align these rods, blocking the reflected light once more.
I think squishing it makes the crystals go all wibberly woberly and that makes 'em invisible and the chip makes great big sploshes of electricity that makes the crystals do as there told again....cheers.
OK, there is something seriously suspicious happening here. This image at 9:16 clearly shows a happy face with a bottle of booze. Yet everyone knows this RU-vid publisher *ONLY* drinks beer in cans. A few seconds later "whoosh" and the bottle evidence is gone!
Quite the interesting circuit. I would imagine you are spot on with the theory of it depending on frequency as opposed to voltage. A smart breakdown, but still leaving many questions and clueless meandering for everyone. {chuckles}
It would be interesting to get one of the large ones, 8.5 inch, and see if it could be modified with a clear back and backlighted. Maybe converted with lenses for projection. Oh, wait they have those.
That chip pin out suspiciously looks like a 555. Button on the right place, outs on the correct pins and the control voltage in on the right pin as well.
I had one of these in a larger size, it used an e-paper element not an LCD. And the pressure of bending or scribing on it puts enough energy to change the pixels until the button is pressed and the clear signals are passed. I didn't realize how simple the clear circuit really is though.
@@allensmithphotography - Well, actually THEY ARE LCD panels - however they (basically) work in reverse to the type we normally see on appliances.. With a normal LCD, small areas can be energized to align the "crystals" and block light, making them appear black. When power is removed, they fall back to their default state of "clear" again. With these panels, the default state is also clear and a black background shows behind them. When pressure is applied the crystals get squashed between 2 plastic sheets, and the pressured ones become reflective. These areas block the black (behind) and reflects light that is striking the tablet, making a whitish silver line appear. When a shot of electricity is applied, the "deformed areas" of LCD get zapped back into their default state (clear) again. You can Google to confirm that they are LCD and also how they operate. Yours might have used a different technology, but THESE are LCD.
@@allensmithphotography - NOT ALWAYS. In a conventional LCD screen, it requires constant power to make the segment opaque (usually black). When you release the power (switch it off) the LCD crystals fall back to their natural state (which appears clear). ... Well, it's EXACTLY the same with these screen... their natural "unpowered state" is also clear, however instead of a reflective background (behind the liquid crystals) these screens have a BLACK background behind the crystals. So, with no power applied, the screen appears black - no power is required to make it black! ... When you write on these, the floating crystals get "stuck" to a plastic sheet. This places them into a orientation that is reflective, so the "written on areas appear "silverish". It stands out because the rest of the crystals are clear, so you can see the black background through them. .... Once the crystals get into that "reflective" state, they stay there. That is caused by some specifically unique properties of the Liquid Crystals, as well as the plastics that they use. Overall, it's sort-of like how an Etch A Sketch works. ... No power is required to keep the crystals in either the reflective or clear state, they just sit there. This is the difference between an "Active LCD Display" and these LCD Writing Panels - in the Active LCD the crystals are not held by anything, so they immediately fall back to "clear" when power is removed. ... On these LCD panels, power is ONLY required in these panels to "zap"" the crystals back into their original clear state. I've wasted enough time trying to patiently explain this to you. If you want to learn (rather than argue) then simply Google for *_"How Liquid Crystal Displays Work in an eWriter?"_* 👈
Ah! That settles it. Works by magic. Maybe a 20V charge reservoir is slung pos-neg/neg-pos with an H-bridge to erase? (sigh) ... the pressure-sensitive LCD cannot really be used as a display, unless one is the artistic type. Might be able to get a 3d printer to put some real fancy art on one.
Shame you can't get the chip #s like you can from an engine block when they are ground-off, ie, you polish it flat and heat with an oxy until the #s raise and you can read them - lol -.
Probably not ground off - just that it never HAD any markings. Although some ICs are marked underneath (pins side). For high volume manufacturing you can anything you like marked on the chips. If you only use one kind (per PCB) then you don't need to know the part number and neither does the Pick-And-Place machine.
Those are way too expensive for what they are. For the price they ask they could easily include (and still make a large profit) a microcontroller (arduino would do) to capture the x/y coordinates and pressure and create a bitmap or better (cause it would be smaller) a vector file on an SD card which you could then download to a computer to view what you had drawn. It would be a el-cheapo digitizer note taking thing but it would do the job and would justify the robbery of a price those have. (Last one I saw was over €70 even at €35 they could do what I propose and make a LOT of profit)
