1stVision Inc. – Machine Vision Articles

A successful, cost-effective application of a Machine Vision system is often dependent on the interplay of many individual elements, including machine vision lighting.  As much as an Light Emitting Diode (LED) appears to be a basic electronic component, driving it in a fashion suitable for machine vision applications is non-trivial.

LED’s have become the staple in industrial imaging applications in which consistent illumination is key.  In order to achieve constant illumination and synchronization with cameras, controllers from Gardasoft should be utilized.  

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Why use a LED Lighting Controller?

LED Light Controllers are an essential element of any vision system which needs to optimize illumination intensity and precision trigger sequencing between vision cameras and lights. The following are the main areas where you will benefit from the use of an LED light controller:

Pulse (or strobe) control
Where you need to synchronize the ON time of your light with the camera and target product (controllers are available for nano-second timing resolution)

Overdriving
Where you require increased intensity from your LED light for a short, defined, period of time (with up to 10x over driving capability)

Continuous current power supply (constant light)
Where you require a highly stable constant current supply for constant on LED lighting

Control of multi-lighting schemes
For systems with multiple lighting configurations which require intensity control and high speed synchronization (from single or multiple triggers)

Remote configuration changes
For systems where it is advantageous to have remote setting of lighting system parameters – eg: to facilitate efficient set-up during system commissioning


LED Technology Overview

LEDs are current driven devices.  While LED Lights are specified as either 12V or 24V lights, the actual LEDs are semiconductor devices whose light output is a direct result of the current through the device, not the voltage. 

All LED device manufacturers specify that current control is advised for efficient use.  Typically, LED datasheets will indicate that very small changes in LED voltage results in large changes in the LED current; and large changes in LED current results in large changes in light output intensity. 

As seen in the diagram to the right, small changes in forward voltage (Vf),greatly change current ( If )

Gardasoft LED controllers regulate the current, not the voltage, so that light output is stable, tightly controlled and highly repeatable. 

Controlling the current allows for precise control of the LED light output, with an additional   benefit to users looking to overdrive their lights to increase light output.


There are many advantages of accurate pulsing and over driving LED’s.  However it is also extremely important to ensure LEDs are over driven safely to ensure long life and not catastrophic failure.   

In this white paper, the following topics are covered:

• An overview of LED technology
• How to pulse and overdrive LEDs safely using Gardasoft’s patented “SafeSense” technology
• Three trigger modes from constant, pulses and switched for various applications.
• How “SafeSense” technology determines the optimum current for consistent LED drive. 
• Advanced and custom controller functions.  Example – allowing multiple pulses at different intensity levels over various LED channels.  

1st Vision has over 100 years of combined experience in industrial imaging and has a resident lighting expert on hand. 

Contact us for pricing on all Gardasoft controllers and suggestions on your vision and lighting application.