OPTO-ASIC Sensors
OPTO-ASIC Sensors
Basic Concept
RENCO has developed an integrated data/commutation OPTO-ASIC which;
- Enables operation at higher frequencies and temperatures.
- Allows us to reduce costs.
- Uses a single LED for reduced current consumption and increased reliability.
- Withstands higher levels of surface contamination on optical components.
Motivation
Our experience in the motion control industry has shown that there is an increasing need for lower cost, higher performance products. To meet this need, we had to reduce manufacturing costs, while improving reliability and performance. This has been accomplished by developing and OPTO-ASIC which combines a unique set of features that have been optimized to meet the needs of this industry.
Product Definition
The OPTO-ASIC sensor consists of four functional elements; the Data Sensor, Data Sensor Signal Conditioning, Commutation Sensor, and Commutation Sensor Signal Conditioning. These components have been fabricated on a single silicon substrate. Product design has been optimized for utilization of this sensor in a Chip-On-Board fashion.
- Data sensor
This sensor utilized a "Phased-Array" structure for the sensor layout. This structure is inherently self-balancing, so it eliminates manufacturing or installation alignment steps. In addition, it is extremely resistant to contamination of the optical surfaces. Basically, as long as there is adequate illumination, the device will work. Jitter, phase and symmetry variation are dramatically reduced using this sensor configuration - Data sensor signal conditioning
The sensor signals are amplified filtered and compared to develop the digital encoder outputs. In addition, an integral multiplication of 2 has been incorporated to provide the opportunity for higher resolution outputs with a smaller optical radius, or than traditionally available from metal code-wheels. For example, using glass code wheels, we can provide up to 2048 CPR in a size 15 encoder. Until now, products using metal code wheels in this size encoder have been limited to 512 CPR. However, with our 2X capability, we expect to be able to provide metal disk products at up to 1024 CPR in this frame size. Finally, we have incorporated reverse voltage and output short circuit protection. Data channel outputs provide an Open Collector interface. - Commutation sensor
The commutation sensors are bulk silicon photo-diodes arranged in a vertical array. These allow three-channel sensing of rotor position for brushless motor applications. Because of our patented design, we achieve the benefits of a fully differential sensor configuration using only three sensors instead of six. This has many benefits, including reduced code-wheel size, improved code-wheel rigidity for metal disk applications, smaller product designs, and retains the advantages of differential sensing. - Commutation sensor signal conditioning
The sensor signals are amplified filtered and compared to our patented pseudo-differential reference signal to develop the Hall-equivalent commutation signal outputs. These outputs provide an Open Collector interface, and include reverse voltage and output short circuit protection.