Browse Prior Art Database

Dome Lift Overload Sensing Device

IP.com Disclosure Number: IPCOM000110154D
Original Publication Date: 1992-Oct-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 1 page(s) / 52K

Publishing Venue

IBM

Related People

Rieland, RA: AUTHOR

Abstract

Described is a hardware implementation for a dome lift overload sensing device for use with robotic arms in the fabrication of semi-conductor wafers. The device is designed to protect the wafers and the automation equipment from damage due to system malfunction, or manual errors, by utilizing sensing units that detect abnormal force conditions.

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Dome Lift Overload Sensing Device

      Described is a hardware implementation for a dome lift overload
sensing device for use with robotic arms in the fabrication of
semi-conductor wafers.  The device is designed to protect the wafers
and the automation equipment from damage due to system malfunction,
or manual errors, by utilizing sensing units that detect abnormal
force conditions.

      Typically, a load arm is used for loading and unloading wafers
into an evaporator chamber.  In prior art, collisions could occur due
to malfunctions or manual errors.  The concept described herein
provides a sensing device to protect the load arm and the wafers from
damage due to malfunction of the vertical axis of the load arm.  The
overload protection device utilizes a spring-loaded mounting design
for the drive cylinder which provides a vertical deflection dependent
on the arm load.  The drive cylinder is preloaded with no dome
present and increases twenty pounds with a fully loaded dome.  A
slotted flag is used to allow a fiber-optic through-beam sensor to be
sensed whenever the load is in the normal operating range.  Loads
outside of the normal operating range will cause the beam to be
interrupted and the motor will turn off.  The width of the slotted
flag is minimized to decrease mounting sensitivity and to increase
detection level consistency.  The initial flag position and the
sensor sensitivity are adjustable to allow for load tolerances and
future payload chan...