keypad membrane / keypad membrane

while a blind person using a common keypad ,he must remember every key-press' position.
it's very inconvenient for them.
this design is a keypad membrane with braille printed on it .when cling the membrane to
the keypad,the blind person can use the common keypad easier and more familiar.
comparing with the special keypad produced just for the blind person,this design is more
economical and convenient.