100 Words Leapfrog Toy Teardown
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- Опубліковано 18 тра 2024
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Sure, a capacitive sensor could be made with a single plate/trace... especially when it has such a large surface area... Imagine earth and/or the atmosphere as the other plate... a certain amount of charge could be placed on the real plate, and it would have some tendency to stay on the plate... moving your hand nearby could either attract more charge to the plate or repel it off the plate.
I imagine the bigger problem in such cases is things like 60Hz noise, which can easily be coupled-in...
So, my guess is they intentionally charge/discharge the plate very quickly/repeatedly (maybe even microseconds) and determine if the discharge rate has shortened/lengthened beyond some threshold.
Maybe for the sake of power-savings they might charge it once and wait for it to deplete on its own (which could ideally be never), then do the quick-cycling, briefly, to detect whether it was caused by a change in capacitance or natural discharge through the sensor-circuit's loading, or 60Hz noise.
I rather doubt they use more sophisticated techniques like looking at the frequency/phase-response of the dielectric, since that'd require ADCs and DSP, rather than some simple schmitt-trigger microcontroller-GPIOs switching from output (to charge) to input (to determine how long it takes to discharge)
This was a fun video
The follow up yes! Neat stuff man, how curious indeed. Thanks again my man
Dude this is freaky coincidence. My son just got this as a birthday gift this weekend
See if you can figure it out.
it's 100% capacitive, because it seems that the "wires" to each touchpad are dashed not a full coper wire from the white pcb to the pads.
Under the brown pcb on the right, there are 6 "switches" not even real microswitches, just plain copper strips that are pressed to a copper pad on the pcb,
these get activated by a notch on each page.
One of these switches detect when you open the book, the other 5 switches forms a matrix with the touchpads on the white shell and purple bottom.
10 touchpads per page X 5 pages = 100 Words
The middle sliding pages itself contains nothing special, only the notch to let the MCU known which page is open.
Also capacitive switches consumes way less power then Infrared sensors would use, because with Infrared these are LED diodes that are allways on or use polling X times per second to stay standby. A capacitive switches consumes zero power while it is not pressed, so zero power during "standby".
Also if Infrared sensors was used, the camera would have picked this up.
Bjorn, do you have insight to how the device can determine there's an input without physical input (just close proximity)? Is the signal so sensitive that the pads dampen it when a finger is near?
@@BetterBiomedChannel , the "touch" circles on each page are transparant for the proximity to work. Imagine this device like 5 stacks or piles, with each stack 20 cd's. These stacks represent the pagesides, and the cd's represent the positions on each page. The MCU knows by the pageswitch on which page (stack) you are, and then the proximity sensors determine which cd is touched. So per example on first stack, the second cd has the value "bear", the second stack , the second cd has another value, because another pageswitch is selected. In short it's a 20 keys keypad, but with a 5 positition selector switch, each key can give 5 different values (5 pages). In the white shell are 10 proximity sensors, and in the purple shell are 10 proximity sensors. Those 10 from the white shell are choosen when you press on the left side of the book, those 10 from te bottom shell are used when you touch the pages on the right side of the book.
@@BjornV78very cool, thanks for sharing