Liftable keyboard

A liftable keyboard for use with a portable electronic device having a top cover and a base with a sensing element, the liftable keyboard comprising:

• at least one key unit, each of which comprises a keycap and an elastomer aligned with the keycap and having an elastomeric chamber;
• a membrane switch circuit layer comprising at least one gas-inputting port and at least one gas-outputting port, wherein the at least one gas-inputting port is aligned with an opening of the elastomeric chamber;
• and
• a micro pump located under the membrane switch circuit layer, comprising an inlet, an outlet and a piezoelectric actuator, wherein the inlet is in communication with the at least one gas-inputting port of the membrane switch circuit layer, and the outlet is in communication with the at least one gas-outputting port of the membrane switch circuit layer,
• wherein when the sensing element of the base of the portable electronic device senses that the top cover is close to the base, the piezoelectric actuator of the micro pump is actuated, so that a volume of a gas-collecting chamber of the micro pump is changed and a pressure difference is generated to perform a gas-extracting action, wherein while the gas-extracting action is being performed, a gas in the elastomeric chamber is extracted downwardly from the opening of the elastomeric chamber, passing through the at least one gas-inputting port of the membrane switch circuit layer and entering the micro pump through the inlet thereof, after which the gas is outputted from the micro pump through the outlet thereof and is discharged from the at least one gas-outputting port of the membrane switch circuit layer, so that the elastomer is subjected to compressed deformation, wherein the keycap is moved downwardly in response to the compressed deformation of the elastomer so as to reduce an altitude of the at least one key unit.