Reliable detection of targets varying in position

Edited by the Engineeringtalk editorial team Jan 26, 2001

A revolutionary area spot laser optic sensor from Keyence enables reliable detection of targets which vary in position, i.e on a parts feeder, chute or production line.

A new linear, area spot sensor from Keyence is unaffected by change in target position.

This revolutionary sensor enables reliable detection of targets which vary in position i.e on a parts feeder, chute or production line.

Now 3 or 4 traditional photoelectric sensors can be replaced with a single unit! The LV-H42 with up to 1000mm detecting distance and an area inspection width, variable with slit plates, of 92mm at 400mm detecting distance, enables problems with small spot sensors such as product Markings, Flaws or Patterns on a target to be ignored.

And it just measures an incredible 35x20x12.4 mm.

Ever tried detecting a (Small) Target that Changes in Position - with ONE sensor ? Thats right, its nearly impossible ! Many of you will have experienced this problem, which in some form occurs on almost every machine and industry.

If you have not then you most probably will in the future.

Imagine for example a 10mm object moving along a 100mm wide conveyor.

Detecting it may be simple, but what if the object may pass anywhere across the conveyor width ? Now an easy application becomes a 'difficult' one.

The obvious solution may be to simply use a thrubeam sensor, however this is not always practical as there may be no space to mount such a sensor either side of the target to be detected.

Therefore the only choice may be to use a reflective sensor.

Using one 'round beam spot' reflective sensor to cover the whole 100mm width though is not accurate, especialy if the target is small.

Sensors with a small beam spot are more accurate but they cannot cover the range of positions that the target may pass through.

A traditional solution then is to mount several reflective sensors across the conveyor width, to detect any target in any position.

All the sensor outputs then are taken to a PLC and if any one turns ON, a target has been detected.

Well, its one solution yes, but any engineer can see that its not the most efficient.

More sensors mean more design, installation and wiring, all of which are time consuming.

The cost as a result is high, not to mention the cost of the sensors themselves.

A good solution is a vision system but depending on the budget this may not be possible.

The New LV-H42 series uses a Wide Area, laser beam spot.

This means that a Single Sensor can be positioned so that its 'linear' beam spot covers the whole width of the area to be inspected.

Anything that passes through the linear beam spot is detected.

Linear area can be adjusted either by adding slit plates or by adjusting the detecting distance.

And its laser light source means an incredible 1000mm detecting distance.

For example, when positioned at 500mm detecting distance, a 120mm linear spot is produced ! Can you imagine all the other types of 'difficult' applications this sensor can solve ?.