Automatic distribution apparatus and method of distribution

Details Automatic distribution apparatus and method of distribution Automatic distribution apparatus and method of distribution

1999-04-12

2001-05-29

Warden, Jill (Department: 1743)

Chemical apparatus and process disinfecting, deodorizing, preser

Control element responsive to a sensed operating condition

C422S091000, C422S105000, C422S065000, C436S180000, C073S863320, C073S864140, C073S864240

Reexamination Certificate

active

06238626

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to an automatic distribution apparatus and a method of distributing samples or reagents used in biochemical and the like fields.
BACKGROUND OF THE INVENTION
Distributing liquid samples or reagents to a plurality of sample vessels in small quantities is an indispensable operation during experiment or analysis activities in the biochemical field, for example. The distribution is performed by sucking/discharging liquid through a distribution nozzle. The distribution nozzle is normally fitted with a disposable distribution tip. The distribution tip is replaced with a new one at any time whenever necessary.
A distribution tip is fitted to the distribution nozzle by inserting the lower end of the latter into a pipet-shaped distribution tip. The firmness of fitting depends solely on the elastic fastening force of a resin distribution tip surrounding the lower end portion of the distribution nozzle. Because of dimensional dispersions in the inner diameters of distribution tips, the fastening forces sometimes fall short of a level required to insure a normal fitting state. This invites a misfitted state with the distribution tip.
During a distribution operation, if a distribution head proceeds without having a distribution tip perfectly fitted thereto, a receiving plate will have a portion void of sample liquid. For assuring reliability of the test result, misfitting of a distribution tip should be avoided by all means. In a conventional apparatus, where a single distribution tip is used, the existence, or non-existence, of a distribution tip may be checked upon through an electrical conductivity test using a conductive material for the distribution tip. Or, it may be confirmed indirectly by watching a pressure during a suction operation. The above-described checking methods, however, are hardly applicable to a distribution head that has multiple distribution tips. The problem with the conventional automatic distribution apparatus is that it is difficult to detect a misfitted distribution tip with a high certainty level.
SUMMARY OF THE INVENTION
An automatic distribution apparatus for distributing liquid is designed such that a distribution tip attached detachably to the lower end of a distribution nozzle can be replaced at any time whenever necessary. The automatic distribution apparatus comprises a fitting stage that supports a holding member holding a plurality of unused distribution tips lined up thereon to have the unused distribution tips fitted to respective distribution nozzles, and detection means for detecting, after a fitting operation is finished, whether or not there is a distribution tip left behind on the holding member without being attached to a distribution nozzle. In a distribution apparatus having the above-described structure, misfitting of a distribution tip can be detected with a high certainty level at an early stage before the apparatus proceeds to a suction/discharge operation.
An invented distribution apparatus further comprises a light sensor, whose optical axis is in parallel with the aligning line of distribution tips disposed on the holding member. This further improves the accuracy of detection.


REFERENCES:
patent: 4478094 (1984-10-01), Salomaa et al.
patent: 5039615 (1991-08-01), Takahata
patent: 5102623 (1992-04-01), Yamamoto et al.
patent: 5273717 (1993-12-01), Marvin
patent: 5363885 (1994-11-01), McConnell et al.

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