Apparatus and method for dispensing small quantities of particles

Apparatus for dispensing particles, comprising:

• a particle retainer for retaining a supply of the particles to be dispensed;
• a particle release actuator for causing, in response to an actuation signal, some of said supply of particles to be dispensed from said particle retainer;
• a weight measuring device for measuring the apparent weight of particles dispensed from said particle retainer and for outputting a signal representing the measured apparent weight;
• and
• a processor operatively connected to said particle release actuator and arranged to output said actuation signal thereto and operatively connected to said weight measuring device and arranged to receive said measured apparent weight signal therefrom, said processor being arranged to estimate the actual weight of particles dispensed by adding a correction value to said measured apparent weight, said measured apparent weight signal being less than the actual weight.

A method of accurately dispensing particles, comprising the steps of:

• retaining a supply of particles to be dispensed, said particles clogging a plurality of apertures;
• vibrating said supply of particles to thereby cause said apertures to become unclogged so that some of said supply of particles is dispensed through said plurality of apertures from their retained position to a position where their weight can be measured;
• measuring the apparent weight of said dispensed particles;
• and utilizing said measured apparent weight to control particle dispensation.

A method of accurately dispensing particles, comprising the steps of:

• retaining a supply of particles to be dispensed;
• causing some of said supply of particles to be dispensed from their retained position to a position where their weight can be measured;
• measuring the apparent weight of said dispensed particles;
• estimating the actual weight of particles dispensed by adding said measured apparent weight to a positive correction value to thereby reduce the effects of delays in obtaining a correct weight measurement;
• and
• utilizing said measured apparent weight to control particle dispensation.

A method of estimating an actual weight of particles dispensed onto a weight measuring device having a non-instantaneous reaction time, the method comprising:

• retaining particles to be dispensed;
• actuating a particle release actuator to cause some of said particles to be dispensed to said weight measuring device;
• obtaining a measured apparent weight;
• and
• adding a correction value to said measured apparent weight, said correction value being derived by summing weighted amounts of a value representing the average weight dispensed in one actuation.