Rotating Vacuum Gripper for Glass Substrate Squaring
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Solution Overview
Problem
Conventional gripper devices for handling large glass substrates in the Flat Panel Display industry lack rotational degree of freedom, leading to inefficient squaring and indexing processes, requiring multiple handoffs and increasing machine cycle time and positional inaccuracies due to stiffness issues.
Innovation Solution
A method and apparatus utilizing motorized vacuum grippers that can rotate about the Z-axis, allowing for simultaneous gripping, squaring, and indexing of glass panels without the need for handoffs, employing a pneumatic system with air bearings and flow restrictors to maintain a consistent gap above the air table and provide rotational and lateral movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional gripper pad with leaf spring is used to provide vertical compliance, then the glass substrate can remain floating above the air table, but the gripper cannot permit rotational degree of freedom requiring handoff to a rotational cup for squaring/alignment
Solution Approach 1:
The patent combines the vertical compliance function (leaf spring) and rotational degree of freedom (cup mechanism) into a single integrated gripper device. The cup-shaped gripper pad can both float above the air table surface and rotate about the Z-axis, eliminating the need for separate handoff operations between different devices.
Solution Approach 2:
The gripper device is designed to perform multiple functions simultaneously: it provides vertical compliance to maintain the air cushion, enables rotational motion for squaring/alignment, and maintains gripping force throughout these operations. This multi-functional design replaces the need for multiple specialized devices.
2Force
If a rigid vacuum pad is used for gripping, then strong gripping force is achieved, but the gripper cannot maintain the nominal gap above the air table during manipulation
Solution Approach 1:
The patent changes the mechanical compliance parameter of the gripper by incorporating a leaf spring mechanism that allows vertical motion. This enables the gripper to adapt its position dynamically while maintaining the nominal gap above the air table surface, preventing the glass from being dragged down during manipulation.
3Manufacturing precision
If multiple handoffs are used for squaring and indexing operations, then rotational and positional adjustments can be performed, but machine cycle time increases and positional accuracy decreases
Solution Approach 1:
The patent enables continuous manipulation operations by allowing the gripper to perform both gripping and rotational squaring operations without releasing the substrate. The cup-shaped gripper maintains continuous contact and control throughout the squaring and indexing processes, eliminating idle handoff time and maintaining positional accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables continuous manipulation of glass substrates without the need for handoffs, reducing machine cycle time and improving positional accuracy by allowing rotational and lateral movement, while eliminating the need for costly and complex machine structures.
Implementation Method 1
gripping a lower surface of the substrate with a master vacuum gripper
Implementation Method 2
transported by floating on a pressurized air table... The air cushion between the substrate and air table enables ease of manipulation
Data Source
AI summary
A vacuum gripper for use in substrate positioning operations includes a vacuum pad adapted to make contact with the substrate and a shaft connected to the vacuum pad. The shaft is characterized by a first diameter at a portion of the shaft proximal to the vacuum pad and a second diameter at a portion of the shaft distal to the vacuum pad. The vacuum gripper also includes a first air bearing surrounding the portion of the shaft proximal to the vacuum pad, a second air bearing surrounding the portion of the shaft distal to the vacuum pad, and an air source in fluid communication with the first air bearing and the second air bearing. The vacuum gripper further includes an exhaust port, a valve in fluid communication with the exhaust port, and a first flow restrictor in fluid communication with the valve.