Plunger homing mechanism for use in chromatography

Claim 2

A syringe plunger homing apparatus comprising: a casing having a recess therein; a housing adapted to fit within said recess; a plunger cap holder adapted to slidably fit within said housing and hold a plunger cap; holder means for biasing said plunger cap holder into contact with said housing; an isolation spring biasing said housing away from said casing; retaining means, associated with said housing and said casing, for retaining said housing within said casing; and sensor means, associated with said housing and said casing, for detecting relative movement there between.

Claim 3

A syringe plunger homing apparatus as in claim 1 wherein: said holder means is a spring that is stiffer than said isolation spring, whereby said isolation spring compresses before said spring.

Claim 4

The syringe plunger homing apparatus as in claim 1, wherein said sensor means comprises: a mechanical switch.

Claim 5

A syringe plunger homing mechanism as in claim 1, wherein said sensor means comprises: a photo detector.

Claim 6

A syringe plunger homing apparatus as in claim 4, further comprising: a sensor holder adapted to accommodate said photo detector mounted on said casing; and a sensor flag mounted on said housing in a position capable of being detected by said photo detector.

Claim 7

A syringe plunger homing apparatus as in claim 5 wherein said photo detector and said sensor flag are adjusted to sense a predetermined movement of said housing relative to said casing.

Claim 8

A syringe plunger homing apparatus as in claim 6 wherein said predetermined movement comprises: movement of 1/8th of an inch or less.

Claim 9

A syringe plunger homing apparatus as in claim 1, further comprising: means for moving said casing relative to a syringe body.

Claim 10

A syringe homing apparatus for holding and positioning a syringe plunger as used in an automated chromatograph comprising: a plunger carriage movable in a linear direction, a casing mounted on said plunger carriage; a housing adapted to hold a plunger cap positioned within said casing; an isolation spring biasing said housing away from said casing; a retaining ring holding said housing within said casing; a first component of a sensor attached to said casing; a second component of a sensor attached to said housing in a position to be detected when said housing moves relative to said casing; and means for stopping relative movement between said casing and said housing when said first and second component of a sensor detect a relative movement between said casing and said housing.

Claim 11

A syringe homing apparatus for holding and positioning a syringe plunger as used in an automated chromatograph comprising: a plunger carriage movable in a linear direction, a casing mounted on said plunger carriage; a housing adapted to hold a plunger cap positioned within said casing; an isolation spring biasing said housing away from said casing; a retaining ring holding said housing within said casing; a first component of a sensor attached to said casing; a second component of a sensor attached to said housing in a position to be detected when said housing moves relative to said casing; and means for stopping relative movement between said casing and said housing when said first and second component of a sensor detect a relative movement between said casing and said housing.

Claim 12

A syringe homing apparatus as in claim 9 wherein: said first and second sensors detect relative movement less than 1/8th of an inch.

Claim 13

A syringe homing apparatus as in claim 9 wherein said first and second component of a sensor comprise: a photo detector and blocking flag.

Claim 14

A syringe plunger homing apparatus comprising: a casing having a recess therein; a housing adapted to fit within said recess; a plunger cap holder adapted to slide within said housing and hold a plunger cap; a holder spring biasing said plunger cap holder into contact with said housing; an isolation spring biasing said housing away from said casing; retaining means, associated with said housing and said casing, for retaining said housing within said casing; sensor means, associated with said housing and said casing, for detecting relative movement there between; and a syringe having a plunger and a plunger cap adapted to fit within said plunger homing apparatus.

Claim 15

A syringe plunger homing apparatus comprising: a casing having a recess therein; a housing adapted to fit within said recess; a plunger cap holder adapted to slide within said housing and hold a plunger cap; a holder spring biasing said plunger cap holder into contact with said housing; an isolation spring biasing said housing away from said casing; retaining means, associated with said housing and said casing, for retaining said housing within said casing; sensor means, associated with said housing and said casing, for detecting relative movement there between; and a syringe having a plunger and a plunger cap adapted to fit within said plunger homing apparatus.

Claim 16

A plunger homing apparatus for use in obtaining a precise sample for analysis as used in chromatography comprising: a casing; first motor means, attached to said casing, for linearly moving said casing up and down; a housing adapted to fit within said casing and slide freely therein, said housing having an interior reference surface for mating with a plunger cap; a first spring extending around said housing for biasing said housing away from said casing; a retaining ring attached to said casing for retaining said housing within said casing; a plunger cap holder extending through said casing and adapted to slide freely within said housing; a second spring extending around said plunger cap holder for biasing said plunger cap holder against the reference surface; locking means, attached to said plunger cap holder, for selectively locking said plunger cap holder in a raised position; a syringe body holder; second motor means, attached to said syringe body holder, for linearly moving said syringe body holder up and down; control means, coupled to said first and second motor means, for controlling the relative linear movement of said casing and said syringe body holder; and detector means, coupled to said casing and said housing, for detecting relative movement therebetween, whereby a syringe plunger can be positioned at the bottom of a syringe body without damaging the syringe and permitting an accurate and precise sample to be taken for analysis.

Claim 17

A plunger homing apparatus for use in obtaining a precise sample for analysis as used in chromatography comprising: a casing; first motor means, attached to said casing, for linearly moving said casing up and down; a housing adapted to fit within said casing and slide freely therein, said housing having an interior reference surface for mating with a plunger cap; a first spring extending around said housing for biasing said housing away from said casing; a retaining ring attached to said casing for retaining said housing within said casing; a plunger cap holder extending through said casing and adapted to slide freely within said housing; a second spring extending around said plunger cap holder for biasing said plunger cap holder against the reference surface; locking means, attached to said plunger cap holder, for selectively locking said plunger cap holder in a raised position; a syringe body holder; second motor means, attached to said syringe body holder, for linearly moving said syringe body holder up and down; control means, coupled to said first and second motor means, for controlling the relative linear movement of said casing and said syringe body holder; and detector means, coupled to said casing and said housing, for detecting relative movement therebetween, whereby a syringe plunger can be positioned at the bottom of a syringe body without damaging the syringe and permitting an accurate and precise sample to be taken for analysis.

Claim 18

A plunger homing apparatus as in claim 13 wherein: said second spring is stiffer than said first spring, whereby said first spring compresses before said second spring.