System and method for operating a pump in a humidifier

A pump arrangement for powering a pump in providing a controlled volume of water to a drip nozzle in a drip-feed humidifier, the pump arrangement comprising:

• a pump having a solenoid, an armature, a spring, and a diaphragm member, wherein the diaphragm member forms a portion of a pumping chamber and is deformable between an initial position for a given volume of the pumping chamber and a deformed position which reduces the given volume of the pumping chamber, wherein the spring is tensioned to pull the armature back toward the solenoid and move the diaphragm member back to the initial position, wherein the armature is coupled to the diaphragm member to (i) deform the diaphragm member away from the solenoid and the initial position in response to the solenoid being energized for extending the armature, and (ii) to pull the armature back toward the solenoid and move the diaphragm member back to the initial position in response to the solenoid being energized for retracting the armature;
• a processing unit;
• and a power supply electrically connected to the solenoid via a switch (S) which is controlled by the processing unit, the power supply being structured to supply power to energize the solenoid via the switch, wherein the processing unit is configured to pulse width modulate the power provided to the solenoid via the switch, wherein pulse width modulating the power comprises (i) energizing the solenoid for each actuation of the solenoid for extending the armature from a starting position to a fully extended position, and (ii) energizing the solenoid according to a mirror image power drive profile for each actuation of the solenoid for retracting the armature to the starting position from the fully extended position in a quiet manner which is below the given noise threshold of potential disturbance, wherein the mirror image power drive profile, defined via a pump volume having a relative scale from 100 to zero percent corresponding to an overall pump volume range determined via movement of armature positioning from the fully extended position to the starting position, versus an extension time having a relative scale from zero to 100 percent, corresponding to an overall extension time range for movement of the armature positioning from the fully extended position to the starting position, comprises:
• an initial portion of the mirror image power drive profile for providing initial power delivery that decreases at a third overall rate and energizing the solenoid to cause an initial movement of the armature in a direction from the fully extended position to a second position, wherein the initial portion extends over a predetermined initial percentage of both the overall pump volume range and the overall extension time of the power drive profile from the fully extended position of the armature to the second position of the armature, an intermediate portion of the mirror image power drive profile for providing intermediate power delivery that decreases at a second overall rate different than the third overall rate and energizing the solenoid, subsequent to the initial portion, to cause an intermediate movement of the armature in the direction from the second position to a third position, and a final portion of the mirror image power drive profile for providing final power delivery which increases at a first overall rate different than either of the second or third overall rate and energizing the solenoid, subsequent to the intermediate portion, to cause a final movement of the armature in the direction from the third position to the starting position, wherein each corresponding energization of the solenoid is operated in the quiet manner.