LED sheds greater light

Unilux claims its new LED-Series 2000 family of LED strobes combine the operational and environmental benefits of LED with the power of traditional xenon-based strobes. President of the US company Mike Simonis says the new lights “are five times brighter than our first generation of LED strobes, which gives them the same lighting performance as our proven xenon-based lights with only 25% to 35% of the power consumption of our comparable Lith-O-Light strobes. They are also smaller – about one-third the size of the traditional equivalent – and lighter than the xenon lights, and have a greater flash-rate range.

“All this gives printers and converters many more options for mounting lights and adjusting flash rates to maximize inspection capability at full production speed, and reduce the fatigue factor for inspection. This is where our customers told us we needed to be,” he stresses.

Indeed during field testing in Europe, the brightness of the new LED strobe lights had to be reduced, according to Volker Schlevoigt, Unilux EMEA manager. “We showed them the 1000 model of our new LED-Series 2000, the equivalent of our LOL-40 for a slitter, and they loved it, but they said it was too bright,” he says.

“That’s the complete opposite of our first generation strobes. The 30-40msec flash duration on the new lights was too bright when inspecting white material. We can either reduce intensity or flash duration for this type of application, but that’s OK. It’s much easier to harness the extra power than it is to get more light output.

“Our field test on a printing press was also a success,” Schlevoigt reports. “Plant managers are looking to replace strobe lights that eat too many lamps, and again, we need to work with them to adjust the brightness.”

The ability to control the output is one of the major benefits of the new LED strobes, says Matt Runo, Unilux’s chief engineer, who led the yearlong R&D effort to develop the new lights.

“Light output is controlled by varying both the light intensity and the duration or on-time of the light. The perceived light intensity seen by the user is actually a relationship between the intensity of light and the light duration,” he says. “A longer pulse rate – say 65msec – gives you more light, but the sharpness of an image frozen by the action of the strobe degrades with longer durations.

“A longer duration can work well for repeat patterns with larger images. But when you have something small with fine detail, then you need a shorter duration for improved clarity,” Runo continues. “With our new LEDs, you can dial down the light duration below 10msec and mount it close enough to the web so that you can see the fine details. The light duration of the xenon strobes can’t be controlled, so they don’t have the same flexibility provided by their LED counterparts.”

Runo says there are two other benefits to using the new LED technology. “First, the distribution of the LEDs across a large rectangular area combined with focusing provided by the lenses creates an even, consistent lighting pattern across the target area. Users will be able to inspect an area comparable with the LOL family but with an even more uniform illumination. A second benefit is that an LED’s inherent light output is extremely stable and does not suffer from the arc wander and flash to flash variation associated with xenon-based lights. This benefits the user by reducing fatigue and increasing inspection effectiveness.”

According to Unilux, LED’s can last up to eight years, depending on use, and they lower the cost of ownership by eliminating the need to change lamps, avoiding unscheduled outages and lowering power consumption. They do not create ozone during operation, and they require no special disposal methods when they burn out.

The new LED-Series 2000 family, which covers areas from 100-2,500mm, comes with a product-naming convention that corresponds to the coverage area 500mm from the light to the inspection area.

For example, the new LED2000-500, which replaces the LED 5X2, will emit 2,000 lux of illumination on a 500mm width from a distance of 500mm.

This is five times more light than the LED 5X2 produces. In fact at a flash duration of 35msec, the LED2000-500 puts out as much light as the xenon-based LOL IV-20.

Runo concludes: “While the amount of light produced is the same as the xenon lights, which have been workhorse products for years, the lens designs for the new LEDSeries 2000 strobes provide a sharper focus than the xenon lights.

“This benefits the user by concentrating more light on the inspection area with less spillage outside the area of interest.

“Getting the same output or more as a xenon-based strobe was our key objective because light output (brightness and coverage area) was a major issue with our first LED strobes,” says Runo.