Phased array scanners for high-resolution absolute encoders
Evaluation is executed by interpolation ICs using a Nonius calculation, e.g. iC-MN and iCMNF, permitting a very high angle resolution of more than 21 bits, even with code disc diameters of only 26mm. All devices of this series can be used with short-wave blue LED lighting for a high accuracy due to a sharper projection. The iC-PNH comes packaged in a 5x5mm optoQFN.
Compared with conventional absolute encoder sensors, iC-PNH sensors do only scan three incremental Nonius tracks and one 2-bit Gray code, saving on assembly space and simplifying illumination. The smaller scanning surface and the high sensitivity of the sensors help to reduce the amount of power needed for the necessary LED, extending its expected lifetime. The phased arrays can be used with a blue LED to minimize distortion and increase the signal contrast. The encoder typical IR-LED can also be used. Photocurrent signals are converted into low-impedance and interference-resistant output voltages by low-noise amplifiers. Depending on the selected chip, a high transimpedance gain of typical 1 MW means that at an illumination level between 3 to 6 mW/cm2 signal voltages of several hundred millivolts are available at the outputs for the subsequent interpolation device.
iC-PNH devices are available for code discs of 26mm, 33mm, and 39mm diameters and operate with a supply voltage of 4.1 V within a temperature range of -40 to +125 °C.
iC-Haus GmbH – www.ichaus.com
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