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Optech Tech develops colour sensors for photometric apps

Posted: 30 Jun 2006     Print Version  Bookmark and Share

Keywords:Optek  OPB780  reflective colour sensor  photometric applications 

Optek's colour sensors

TT electronics Optek Technology has developed the OPB780 reflective colour sensing assembly that promises to provide design engineers a reflective sensor with the capability to reliably sort or match surfaces by colour.

According to Roland Chapa, director of the company's assemblies business unit, the reflective colour sensor assembly is suitable for use in photometric applications. "The assembly is able to provide high resolution digital measurement of the red, green and blue components of the light reflected from surface being sensed," explained Chapa. "The small footprint of the sensor also makes the device ideal for space-confined areas."

Applications where the colour sensor is being implemented include pill sorting machinery in pharmaceutical applications, ink and/or paper colour detection for office machines, colour printer calibration sensors, as well as colour-match sensing in paint, textile and cosmetic manufacturing.

The assembly's white LED illuminates the surface of the object or liquid being sensed, with the reflected light then received by an 8 x 8 photodiode array. The array consists of four selectable groups of red-, green-, blue- and clear-filtered photodiodes, with each group of 16 photodiodes integrating the reflected filtered light to minimize any non-uniformity. A light-to-frequency converter in the CMOS monolithic sensor enables the assembly to communicate directly with a microcontroller, producing a square wave output with a frequency directly proportional to light intensity, the company explained.

Operating from a 5V power supply, the colour sensor has a typical nonlinearity error of 0.2 per cent at 50kHZ. The LED in the colour sensor assembly has a typical luminous intensity of 1100mcd and a typical forward voltage of 3.6V. Maximum forward current is 30mA, with a pulse forward current of 100mA. The maximum reverse voltage is 5V with a power dissipation of 120mW.

The reflective colour sensor assembly is housed in a plastic design capable of being mounted to a PCB or flush mounted to a surface using clips. From the assembly, the interface to the application is designed for a zip compatible cable, which can be provided as a customer specific design.

The total assembly is 1.08-by-0.843 inches by 0.355 inch tall, allowing it to be incorporated easily to most any application, Optek said. For this assembly, the maximum operating temperature range is -30°C to 85°C.

Typical pricing for the OPB780 colour sensor is Rs.505.96 ($11.04) in quantities of 10,000 pieces. Lead time, if stock is not available, is from 8 to 10 weeks.

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