Adaptive Contact Sensor for Chip Mounting Nozzle
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Solution Overview
Problem
Existing part mounting devices face challenges in accurately controlling the descent stroke of a nozzle due to variations in nozzle shapes and surface conditions, leading to picking-up and mounting errors, as well as insufficient adaptability of contact sensing functions, especially when reflective surfaces become dirty or foreign materials adhere to the nozzle.
Innovation Solution
A part holding head assembly with a contact detecting sensor that includes a light-emitting unit, a light-receiving unit, and a sensor unit, which sets a threshold value based on the received amount of reflected light after completion of T-direction and R-direction rotation operations, allowing for real-time adjustment and generation of contact sensing signals to prevent excessive pressure on parts during mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed threshold value is used for contact sensing, then the device complexity is reduced, but the measurement precision deteriorates due to variations in nozzle conditions and foreign materials
Solution Approach 1:
The patent applies dynamics by making the threshold value adaptive rather than fixed. The control unit dynamically adjusts the threshold value based on real-time light reception amounts from the optical fiber sensor, allowing the system to adapt to changing nozzle conditions, foreign materials, and wear without increasing physical complexity
Solution Approach 2:
The patent changes the parameter of the threshold value from a fixed constant to a variable that is continuously adjusted based on light reception measurements. This parameter change allows the system to maintain high measurement precision across different operating conditions while keeping the hardware simple
2Reliability
If the descent stroke is increased to ensure contact, then the reliability of part pickup is improved, but the part may be broken due to excessive force
Solution Approach 1:
The patent uses feedback from the optical fiber sensor to monitor the light reception amount during nozzle descent. When the received light decreases below the adaptive threshold, the system detects contact and immediately stops the descent, providing real-time feedback control that ensures reliable pickup while preventing excessive force and part damage
Solution Approach 2:
The system takes preliminary action by continuously monitoring light reception and dynamically adjusting the threshold before contact occurs. This allows the system to prepare for contact detection and stop the nozzle descent at the precise moment of contact, preventing the harmful effect of excessive pressing force
3Object-affected harmful factors
If the descent stroke is decreased to prevent part damage, then the harmful factors are reduced, but the nozzle may fail to contact the part due to positioning errors
Solution Approach 1:
The optical fiber sensor provides continuous feedback on light reception during the descent stroke. This feedback allows the system to detect contact at the precise moment it occurs, enabling the nozzle to descend closer to the part without risking damage, thereby maintaining high reliability while minimizing harmful forces
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
This solution enhances the robustness of contact sensing, reduces errors in part picking-up and mounting, and extends the operational lifespan of nozzles by accurately controlling the descent stroke and adapting to changes in light reception due to nozzle conditions, ensuring precise contact detection and reduced risk of part damage.
Implementation Method 1
a light-emitting unit which emits light toward an outside reflective surface of the nozzle, a light-receiving unit that receives reflected light reflected from the outer reflective surface
Data Source
AI summary
There is provided a part holding head assembly of a part mounting device including: a rotary head; a spindle configured to rotate in a first direction T with respect to a central axis of the spindle and configured to move in a second direction Z substantially parallel with an extending direction of the central axis of the spindle; a nozzle provided at a first end of the spindle; a raising part configured to move the spindle to in the second direction Z; and a contact detecting sensor configured to sense the nozzle contacting a part or the part held by the nozzle contacting a substrate and configured to generate a contact sensing signal according to the sensing.