A question about a debouncing circuit
The schmitt trigger doesn't help debouncing in itself. But it is required because after the RC-filter, the signal will have slow rise/fall times (this is obviously the purpose). And signals with slow rise and fall times are not appropriate for feeding regular logic inputs. If the gate inputs stay "inbetween states" for a long time, you'll experience higher power consumption and may see instability problems. This is fixed by the schmitt triggers.

The capacitor can be sized easily, and depends on the "boucing time" indicated in the encoder datasheet. It also depends on the values of the pullup resistors. Basically, take a RC time constant (here 10k * 1µ = 10m) and it should be higher than the max bouncing time.