Wafer Transport Robot Parallel Link Transmission

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Solution Overview

Problem

Conventional horizontal articulated wafer transport robots experience meandering or rolling of the second parallel link due to backlash in gear trains or slips between belts and pulleys, leading to misalignment or interference issues during wafer loading and unloading.

Innovation Solution

A wafer transport robot design featuring a multi-shaft drive unit with coaxially disposed inner and outer shafts, a first parallel link, a second parallel link, and a plurality of rotationally connected transmission arms that transmit operations between the links without causing backlash or slip, ensuring precise alignment through a configuration where the angle between driven and common arms matches the angle between the first and second arms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a gear train is used to transmit operation from the first parallel link to the second parallel link, then mechanical transmission is achieved, but backlash causes meandering or rolling of the second parallel link

Engineering Contradiction:

Improvetransmission accuracyVSAvoidmeandering or rolling

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the gear train mechanical transmission system with a belt-pulley system. The belt connects pulleys on the drive arm and driven arm, transmitting motion without the backlash inherent in gear meshing. This substitution eliminates the source of meandering and rolling while maintaining the mechanical transmission function.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses a flexible belt as the transmission medium between pulleys. This flexible element transmits motion smoothly without the rigid meshing contact of gears, eliminating backlash-induced instability. The belt's flexibility allows for smooth engagement and disengagement while maintaining continuous motion transmission.

Inventive Principle:

Principle #30Flexible shells and thin films

2Ease of operation

If a belt is used to transmit operation from the first parallel link to the second parallel link, then smooth transmission is achieved, but slips between the belt and pulleys cause meandering or rolling

Engineering Contradiction:

Improvesmooth transmissionVSAvoidalignment precision

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent employs pulleys with curved surfaces to contact the belt, optimizing the contact area and distribution. The curved geometry of the pulleys ensures uniform pressure distribution across the belt contact zone, preventing localized slips that would cause meandering. The spherical/cylindrical contact surfaces improve grip and reduce slippage compared to flat contact surfaces.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Device complexity

If gears are used for transmission, then structured connection is achieved, but backlash leads to misalignment or interference during wafer loading and unloading

Engineering Contradiction:

Improvetransmission structureVSAvoidwafer alignment precision

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent substitutes the gear meshing system with a belt-pulley friction-based transmission system. This replacement eliminates the backlash inherent in gear teeth engagement, providing continuous and precise motion transmission. The result is improved wafer alignment precision during loading and unloading operations, as the second parallel link no longer experiences the periodic disturbances caused by gear backlash.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Adaptability or versatility

If belts are used for transmission, then flexible connection is achieved, but slips cause interference of the wafer at its side surface

Engineering Contradiction:

Improveconnection flexibilityVSAvoidwafer side surface interference

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent uses curved pulley surfaces to maximize belt contact area and optimize pressure distribution. This curvature design enhances frictional engagement between the belt and pulleys, preventing slips that would otherwise cause the second parallel link to wander and interfere with the wafer's side surface during transport operations.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Data Source

PatentUS9508581B2Wafer transport robot

Publication Date: 2016.11.29 TATSUMO KK

AI summary

An object is to transmit an operation of a first parallel link to a second parallel link through a plurality of rotatably supported arms, to prevent the second parallel link from meandering or rolling so that a wafer can be transported smoothly.Arms (61 to 63) of a transmission arm unit (6) are provided for transmitting an operation of a first parallel link (4) to a second parallel link (5). An operation of the first parallel link (4) is transmitted to the second parallel link (5) so that an angle between an arm (53) and an arm (52) in the second parallel link(5) always coincides with an angle between an arm (41) and an arm (42) in the first parallel arm unit (4).