Encoder Technology’s Heavy Duty Optical Encoders have been developed utilizing the latest design in Opto IC technology, which is contained in an industrial grade cast aluminum housing.

The basic design consists of only a few components; Photohead Module, Disc, Bearing Assembly, I/O PCB, and Cover.

The Photohead module contains a single Phased Array Opto ASIC which combines multiple photo diodes, amplifiers, comparators and temperature compensation circuits all on one monolithic chip. Phase Quadrature and symmetry are designed into the Opto IC at the wafer level which prevents drift over time and temperature. Encoders of less advanced design all utilize discrete components such as potentiometers, laser trim or mechanical, light distorting screws to achieve balanced outputs.

The Opto IC is of bipolar, differential design for common mode noise immunity and is illuminated by a 100 ma rated GaAlAs LED which is driven at only 20ma. Driving the LED at only 20% of its power rating greatly enhances it’s long term stability and provides a more user friendly encoder where limited source current is a concern. Stable and repeatable output signals are provided below 3.3vdc input levels. Light is transmitted through a custom molded high temperature lens specially designed for the LED wavelength and optical focal length requirements of the encoder.

These three components, the Opto IC, LED and Lens are embedded in a molded Ryton Leadframe which comprises the complete sensing module. This Module was designed as a stand alone optical encoder component for high volume production in the Office and Factory Automation markets. Its use as the basic building block for the industrial encoders greatly increases MTBF while lowering manufacturing costs. The phased array Opto IC and collimated lens allow for the use of a metal disc and a large “air gap” of 0.030 inches. A factor of 10x over other encoders using glass discs. No separate Mylar masks are required due to the interdigitated Opto Diode Array. Use of this unique Opto module design assures performance over a wide standard operating temperature range of -40 to +100 degrees centigrade, with 120 degrees centigrade operation available.

The optical interrupter disc is made of 303, full hard, stainless steel or 100° C Mylar for rigidity, unlike other encoders which may employ fragile and expensive glass discs. The ID of the disc is precisely tooled to the data track optical radius and eliminates the need for manual “disc centering” required with glass discs found in many other encoders.

The bearing assembly consists of a CNC machined frame and a double row, 5500 series, 100 pound load rated, ball bearing and 10mm passivated stainless steel shaft. Optional output shaft diameters are available utilizing shafts stepped down from 10mm. This bearing is proven as it is common to many, industrial encoders being offered on the market today. What makes the Encoder Technology bearing assembly unique and much more robust is the method by which the bearing and shaft are retained... The bearing is secured to the shaft on one end by a Waldes Truarc external retaining ring and on the other by a bolt rated at 1000 lb. The bearing is captured in the encoder housing on one end by a land in the housing and on the other end by an internal retaining ring. Based on typical bearing specs a bearing life of 5 x 10 to 8th revolutions at rated loads, or 5 x 10 to 11th at 10 % of rated loads, can be expected. Present day encoders typically utilize glues, epoxies or thread lock compounds as the sole means by which to secure the bearing, shaft and / or shaft assembly. An optional enhanced shaft seal can be added for harsh environmental applications.

The I/O PC card interfaces with the Photohead module and employs an RS422 compatible, differential line driver, noise filter capacitor, TVS diode for EMI and transient voltage suppression, as well as a Polyswitch to protect the encoder from over or reverse voltage. The PCB employs a ground plane for noise immunity and all components are surface mount. Unlike other encoders, there are no potentiometers or trimming resistors used internal to these encoders. Additionally, there are no mechanical adjustments or “alignments” necessary in the assembly process. All components are hard tooled to fit together without the labor intensive adjustment procedures normally necessary in the manufacture of older style optical encoders. Unlike other encoders, the I/O PCB contains no optical sensing components which, as the PCB flexes with time, temperature or vibration may affect the encoder outputs. This provides for a greatly enhanced MTBF in applications where shock and vibration are present.

The cover is die cast aluminum with a sealed MS connector or optional sealed cable exit. No cover mounting screws penetrate the cover which, if utilized, would be a potential avenue for moisture or other contaminates to migrate into the encoder. The cover is sealed at the base and connector interface through the use of O-Ring seals. Other encoders use discrete wires to the connector and screws that penetrate the cover both of which are a source of failure.

Encoder Technology’s Heavy Duty Industrial Encoders are covered by a three year warranty, exclusive of bearings, which are warranted for one year. Any encoder that fails during the warranty period due to a factory defect will not be repaired, but replaced with a new encoder.