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Touch screens tough it out for roadside measurements

Designing a portable instrument that needs to take measurements quickly in a limited period of time with sufficient reliability to support legal proceedings is a great challenge. Designing a user interface so that the operator can access the full functionality of the instrument quickly and easily is just as important as the electronic and optical performance.

High functionality

The portable ARH CAM-S1 speed camera offers twelve different enforcement and analytical functions, matching or even exceeding the capabilities of much larger fixed equipment. Speed measurement is just one of the many roles this instrument is able to perform. For example it may be set up for lane enforcement to observe not just proper use of parking or bus lanes but also whether solid lines are crossed, road markings and street signs are followed or signal lights are respected. In the latter case after determining the ideal spot for the system, its laser-guided distance measuring can simply determine whether a vehicle came to a complete stop before crossing the intersection next to a stop sign or halted at a red light, as vehicle motion and traffic light sequences are also readily recognized. It not only reads all license plate types in the world, but is also able to detect with high probability whether a driver is wearing a seatbelt or not. The system’s computation and communication capabilities also come in handy during traffic analysis. The unit’s preset functions can count vehicle traffic and monitor the traffic in real-time.

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With its two cameras, ARH’s unit provides overview and high resolution images or videos, and combined with IR illumination, is able to operate at a distance of 600m and read license plates from 150m. Precise location is determined by a built-in GPS, and communication is done with Wi-Fi, GSM or Ethernet. All data processing, storing and forwarding are executed within the unit as well.

User interface design

Law officers and other users will often be under pressure when using the instrument, and may well be working in bad conditions. Having twelve modules in one instrument is a great asset, but also a challenge as the user interface needs to allow operators to navigate those functions quickly and easily, in the dark or in bad weather.

ARH decided that a touch interface was the best way to achieve this. Clearly the touch screen needed to be strong, as the instrument was highly likely to be dropped in use, and needed to be easily read at all light levels.  Control and setup for all the above tasks are carried out on a Zytronic 9” Projected Capacitive (PCAP™) touch screen from through an intuitive graphical user interface.

Commenting, Adrian Cseko, Sales Manager at ARH Inc., said “Speed measuring devices need to operate under harsh conditions, therefore the thickness of the glass was of major importance. It was a high priority to have a tough and secure glass screen that didn’t shatter. This was an important driver behind the selection of Zytronic. Due to its proprietary PCAP™ projected capacitive touch technology, the sensor has been designed with a 5mm thick toughened glass front face, and still responds to even the softest touches. Zytronic was also able to easily customize the size the touch sensor to fit the aperture and dimensions of the pre-existing LCD display.”

Furthermore, the Zytronic touch sensor was designed with an anti-glare treated glass to reduce reflections and ensure good readability even during sunny weather.

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Tough touch environment

With portable instruments especially there is a trend to try and offer more and more functions in one unit, to minimize the amount of equipment field staff have to carry. The semiconductors used to detect, collect, store and communicate data are always coming down in size. It is possible to add more features while forgetting about the user who operates the instrument and sets the right parameters for each measurement situation. A touch interface can be designed to only offer the relevant settings at any one time, so that the instrument remains quick and intuitive to use. The ARH CAM-S1 design shows that such touch screens can work effectively even in demanding outdoor conditions, with light levels ranging from darkness to bright sunlight and the ever-present risk of physical damage. The instrument is now in use with five police forces around the world – clearly the user interface design has been a success!