LED LIGHTING CONTROLLERS
Basic light controllers, whether internal or external, provide a higher-quality regulated electrical power connection, minimizing brightness fluctuations due to power supply issues, and can provide a means to adjust the light intensity.
The intensity can also be adjusted directly, on some lights, via a 0-10V analog voltage signal on one of the cable lines or controller lines, permitting programmatic intensity adjustment via a PLC or other controllable voltage source.
Basic Strobing
When motion is involved, many internal and inline controllers can provide strobe capability to freeze the motion of a moving object to reduce blurring in the image.
With most internal or inline drivers, the width of the light’s strobe output pulse corresponds to the width of the input trigger pulse.
With basic strobing, the light’s intensity will not exceed the maximum “always on” brightness of the light, but the light will “flash” for the specified period, effectively “stopping motion”. If sufficient light intensity and a short enough duration trigger pulse are provided to stop the motion and minimize image blur, say for very slow-moving items, this is an option.
If the acquired image is or may be affected by blurring due to motion artifacts, additional strobe control intensity and triggering options are required.
Overdrive Strobe Function with Inline or Built-in Drivers Increases Light Intensity by 4X-8X
When objects are moving at higher speeds and a shorter exposure is required or when the optical system attenuates the light, internal and inline controllers with “Overdrive” strobe capability may be used. By using a PNP or NPN trigger, these lights will send a higher-than-normal current to the LEDs for a very short period, corresponding to the trigger pulse width, increasing the light’s intensity by 4X-8X during the strobe pulse.
EXTERNAL LIGHT CONTROLLERS
Many external light controllers have knobs/pots to control intensity. While good for lab use, the external controllers are typically triggered programmatically by the machine vision system. The machine vision system or its PLC will trigger the camera and light when an image needs to be acquired.
External light controllers can provide single or multiple channels, triggering capability, and communication between the machine vision control system and the lighting controller. Many provide overdrive capability for higher-intensity strobe applications.
