STEMMER IMAGING

Intelligent lighting - Part 1

In the first of our three part series we'll be looking into simply plugging in a light and using lights that have built in drivers and controllers.

Pulsing / Strobing / Dimming / Overdriving are the techniques that we'll be covering as well.

If you'd like to know how to create detailed lighting designs and sequences then head over to part 2 of this series where we explain how lighting controllers work.

 

LEDS VS ALTERNATIVES

They're on almost every new car that's launched these days...

 

LEDs have a pivotal role in the evolution of machine vision as well

Historically, quartz halogen and fluorescent lights were the most common sources.

Thanks to improved intensities, control, cost effectiveness, and especially longevity, LEDs have surpassed them (in most applications)

LEDs are great for precise control. Not only can you pick a very narrow, specific wavelength of light, very quick on / off and brightness control is also achievable.

Unlike the alternatives, LEDs don’t take very long to reach their full brightness. Enabling much finer control of the lighting

 

...or by using a pulse width modulation (PWM) controller (a way of achieving analogue control using a digital signal)

 

A PWM signal consists of two components:

- The duty cycle, which is the amount of time that the signal is on for during a cycle, and;

- The frequency, how long the cycle takes to complete

Because this on/off switching happens so quickly, the output appears to behave like a constant voltage analogue signal

PULSING (STROBING)

Once you have control of when the light is “on”, the pulses (strobes) can be synchronised to when the product is in the right position

This control is achieved by anything that can provide a digital trigger signal.

Typically this is generated by:

- An encoder pulse, product sensor or PLC signal

- A software trigger (eg the machine vision software)

- The camera itself (some cameras have this feature enabled)

 

INTEGRATED DRIVERS

 

Some lights allow you to feed the digital trigger signal directly into them...

...this is because they have integrated constant current drivers

OVERDRIVING

Running continuously, at their specified current rating, LEDs output 100% of their brightness...

... but it's actually possible to get even more out of the lights

If the current is increased and driven for very short pulses, you can “overdrive” LEDs

To prevent the LEDs from burning out, the amount of time that they are on (in overdrive mode) is limited. They also need enough time to cool down before they are active again.

 

To prevent the LEDs from burning out, the amount of time that they are on (in overdrive mode) is limited. They also need enough time to cool down before they are active again.

In part 2 of this series we cover how you can create detailed designs and sequences for your machine vision application.

Integrated Drivers

Most of the Smart Vision Lights range offers integrated drivers, enabling direct strobe control and overdriving. Smart Vision Lights we're also the first company to introduce a controller directly into a machine vision light.

PWM controllers

The CCS PD2 and PD3 power supplies both offer intensity control via Pulse Width Modulation

Contact

Denmark

STEMMER IMAGING A/S
Vesterbrogade 149, 5th floor, Building 12
1620 Copenhagen V
Denmark

+45 33 73 00 00
dk.info@stemmer-imaging.com

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