Apparatus and method for dispensing small quantities of particles
First Claim
1. Apparatus for dispensing particles, comprising:
- a particle retainer for retaining a supply of the particles to be dispensed, said particle retainer having a plurality of apertures arranged to be clogged by the particles and to be unclogged for dispensing therethrough of said particles;
a particle release actuator responsive to an actuation signal and arranged to vibrate the particle retainer in order to unclog said apertures so as to enable some of said supply of particles to be dispensed from said particle retainer through said unclogged apertures; and
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.
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Abstract
There is disclosed an apparatus and method which is capable of dispensing very small (typically less than 5 mg) quantities of particles to a high accuracy in a repeatable way and without undue wastage. Also, the need for advanced particle formulation is reduced. The apparatus comprises a closed loop control system which uses an electro-mechanical actuator to deliver impact energy to a supply of particles initially held on a sieve in a hopper. The impact energy causes a small number of particles to fall through the sieve and onto a weight measuring balance. The weight obtained is scrutinized by a processor to see if further actuations are required. In preferred embodiments, the energy of actuation is varied in accordance with the rate of dispensation calculated by the processor. Also, a correction amount can be obtained to take account of the fact that the balance can take a considerable amount of time to settle to its final value.
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Citations
82 Claims
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1. Apparatus for dispensing particles, comprising:
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a particle retainer for retaining a supply of the particles to be dispensed, said particle retainer having a plurality of apertures arranged to be clogged by the particles and to be unclogged for dispensing therethrough of said particles;
a particle release actuator responsive to an actuation signal and arranged to vibrate the particle retainer in order to unclog said apertures so as to enable some of said supply of particles to be dispensed from said particle retainer through said unclogged apertures; and
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. - View Dependent Claims (2, 3, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 82)
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4. Apparatus for dispensing particles, comprising:
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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. - View Dependent Claims (5)
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32. A method of accurately dispensing particles, comprising the steps of:
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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. - View Dependent Claims (33, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 70)
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34. A method of accurately dispensing particles, comprising the steps of:
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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. - View Dependent Claims (35)
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81. A method of estimating an actual weight of particles dispensed onto a weight measuring device having a non-instantaneous reaction time, the method comprising:
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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.
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Specification