Contact lens picker

Abstract

A contact lens picker has a linear variable differential transformer (LVDT) operably coupled to a pair of arms, the arms moveable between a release position and a picking position. A controller coupled to the LVDT compares an output of LVDT at successive picking positions to determine whether a contact lens has been picked up.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a perspective view in diagrammatic form of a lens picker of the present invention.

FIG. 2 is a top plan view of the lens picker of FIG. 1.

FIG. 3 is a left side elevation of the lens picker of FIG. 1.

FIG. 4 is a graphical representation of the average and minimum difference values of the linear variable differential transformer between a successful and an unsuccessful pickup for various spherical and toric contact lenses.

FIG. 5 is a graphical representation of the output of the linear variable differential transformer of this invention for a series of 50 pickups of a first toric contact lens.

FIG. 6 is a graphical representation of the output of the linear variable differential transformer of this invention for a series of 50 pickups of a second toric contact lens.

FIG. 7 is a graphical representation of the output of the linear variable differential transformer of this invention for a series of 250 pickups of a series of different toric lenses.

Claims

1. A lens picker for picking up a contact lens comprising: first and second relatively movable arms;a driver coupled to at least one of the arms;a linear variable differential transformer (LVDT) coupled between the arms; anda controller coupled to the arms for sequentially moving the arms between a first release position and a second picking position and comparing an output of the LVDT at successive picking positions to determine whether a contact lens has been picked up.

2. The lens picker of claim 1 in which the controller compares an LVDT output voltage produced at successive picking positions.

3. The lens picker of claim 2 in which the controller causes the arms to be brought to a picking position without a lens present prior to each attempt to pick an actual lens.

4. The lens picker of claim 1 in which the LVDT comprises a coil connected to one arm and a core connected to the other arm.

5. The lens picker of claim 1 in which the controller compares the LVDT output to a threshold.

6. The lens picker of claim 5, wherein the controller compares an LVDT output voltage to a threshold voltage.

7. The lens picker of claim 1 in which the controller comprises an amplifier connected to the LVDT.

8. The lens picker of claim 1 in which the LVDT is mounted to the arms by a shock and vibration reducing mount.

9. The lens picker of claim 1 in which the controller is temperature compensated.

10. A method of picking up a contact lens comprising the steps of: providing a pair of pick up arms movable between an open position and a pick up position;coupling a linear variable differential transformer (LVDT) between the arms;moving the arms to the pickup position with no contact lens disposed between the arms and observing the voltage of the LVDT; andmoving the arms to the pickup position and determining whether a contact lens is present by comparing the output voltage of the LVDT to the observed voltage.

11. The method of claim 10 in which said coupling step comprises coupling a core of the LVDT to one of said pair of arms and coupling the coil of an LVDT to the other of said pair of arms.