The HLC2705 detector is designed to sense speed and direction of mechanical motion. Applications include rotary and linear encoders; the device is especially well suited for the encoding function in an optical mouse. The detector is a monolithic IC, consisting of two narrow adjacent photodiodes, amplifier stages, and quadrature logic which provides two outputs. One is a fixed duration, low level active tachometer (counting) pulse. It is generated whenever the "A" channel illumination passes through the threshold level. The second is a direction output which is set to a logic high or a logic low depending upon which channel is illuminated first. The sensor also has sensitivity compensation circuity for the output power versus temperature characteristic of an IRED. The IC is encapsulated in a molded, unlensed black plastic package which is transmissive to IR energy, yet provides shielding from visible light.
The tachometer output is an NPN collector, internally connected to Vcc through a 10 kOhm (nominal) resistor. The direction output is a totem-pole configuration. Both are capable of directly driving TTL loads.
The tachometer pulse is generated at both the increasing and decreasing illumination thresholds of the "A" channel, resulting in two tachometer pulses for each mechanical period of the interrupter. The HLC2705 is designed to work with a mechanical period as small as 0.036 in [0,914 mm], providing resolution to 0.018 in [0,457 mm].
|HLC2705 Series Infrared Encoder Detectors Catalog Information||Catalog Information||English||312KB|
|Infrared Sensors Line Guide||Product Line Guide||English||1MB|
|Product||Function||Package Type||Output Option||Resolution|
|HLC2705-001||Encoder Detectors||PC Mount||Speed and Direction||0,46 mm [0.018 in]|