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The changing world of sensor technology

The changing world of sensor technology

Jim Braun is the Vice President of Marketing and Product Development with Balluff. He joined Balluff in 2000 after spending most of his career in the design and marketing of industrial control systems for machine tools, robotics, and injection molding machines. Jim is a Cincinnati native and has a BSEE from the University of Cincinnati and an MBA from Xavier University.

Sensor technology continues to change and evolve, in response to growing demand from engineers for smaller sizes, a higher degree of ruggedness, and greater capabilities.

Design News: Sensors are getting smaller. What specifically is driving this trend and what technology developments have made miniaturization possible?

Braun: The need for smaller sensors is driven by two factors: First, more sensors are being used in machines than ever before. Therefore, the physical size of the sensor becomes more of an issue when finding an adequate place to mount it. And, second, miniaturization reduces the amount of raw material used to manufacture the sensor, thereby lowering the overall cost of production. The use of higher scale integration in the electronics and improved software modeling techniques are leading to more functionality in smaller packages.

Q: Is there a practical limit on how small sensors can get?

A: We may be very close to the practical limit on the size of inductive sensors. One obstacle to smaller sizes of inductive sensors is the coil. In general, as the coil size gets smaller, the sensing range is reduced. However, new design and manufacturing techniques are helping to maintain the sensing distance in other ways. Another limitation is the wire size. It becomes very difficult to match the wire size to a small sensor body and also provide a wire size that can be terminated in a practical manner at an interface point on the machine.

Q: Sensors are becoming more ruggedized for the factory floor. What is driving this trend and what technology developments are making this possible?

A: The single largest failure mechanism in sensors is physical damage. This usually occurs when part of the machine makes contact with the sensor. To improve reliability, sensor manufacturers are using very durable and rugged materials in the sensor to help them withstand physical impact. Another engineering design advancement is the increased sensing range available in some sensors. The increased range allows the user to place the sensor out of harm's way in many applications. Balluff has recently launched a series of sensors with 4X the normal sensing distance.

Q: Are today's sensors encroaching on the turf once held by vision systems?

A: Vision systems are still useful in many applications, but new microprocessor-based optical sensors from a range of manufacturers have been able to provide a more cost-effective solution in many applications. A new addition to Balluff's arsenal is the True Color Sensor BFS 26K, which uses a pulsed white light and a three-color receiver with multiple tolerance levels. This eliminates the need for the costly ambient lighting systems sometimes required with vision systems. Also, the small size (50mm x 50mm) and simple teach-in setup make the BFS 26K easy to apply.

Q: What will be the most important sensor development to occur in the next five years?

A: Some people think it will be wireless sensors but I disagree. I think practical wireless technology is more than five years down the road. Smaller sizes, rugged body materials and longer sensing ranges have been the main design thrust for the past few years. But the most important attributes to our customers are cost and reliability. Most capital equipment manufacturers are under constant cost pressures. Anything we can do in the sensor industry to maintain quality, provide expert application assistance and reduce the cost to the customer will have the biggest impact.

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