AEDT-9140 Series High Temperature 115 C Three Channel Optical Incremental Encoder Modules 100 CPR to 1000 CPR Data Sheet Description Features The AEDT-9140 series are three channel optical incremen- Two channel quadrature output with index pulse tal encoder modules. When used with a codewheel, these Resolution from 100 CPR to 1000 CPR (Cycles Per low cost modules detect rotary position. Each module Revolution) consists of a lensed LED source and a detector IC enclosed Low cost in a small plastic package. Due to a highly collimated light source and a unique photodetector array, these modules Easy to mount are extremely tolerant to mounting misalignment. No signal adjustment required The AEDT-9140 has two channel quadrature outputs plus Small size a third channel index output. This index output is a 90 -40 C to 115 C operating temperature electrical degree high true index pulse which is generated TTL compatible once for each full rotation of the codewheel. Single 5V supply The AEDT-9140 optical encoder is designed for use with a codewheel which has an optical radius of 11.00 mm (0.433 Applications inch) for 100 CPR to 1000 CPR and 11.68 mm (0.460 inch) Typical applications include: for 1000 CPR. Printers The quadrature signals and the index pulse are accessed through ve 0.46 mm square pins located on 1.27 mm Plotters (pitch) centers. Tape drives Machine tools Industrial and factory automation equipment. Note: Avago Technologies encoders are not recommended for use in safety critical applications. Eg. ABS braking systems, power steering, life support systems and critical care medical.Theory of Operation Denitions Note: Refer to Figure 2 The AEDT-9140 is an emitter/detector module. Coupled Cycles (N): The number of electrical cycles per revolution with a codewheel, these modules translates rotary motion (CPR). Note: CPR refers to the raw signal from encoder, that of a shaft into a three-channel digital output. is the cycles before 4x decode. As seen in Figure 1, the modules contain a single Light One Cycle (C): 360 electrical degrees ( e). Emitting Diode (LED) as its light source. The light is col- limated into a parallel beam by means of a single poly- One Shaft Rotation: 360 mechanical degrees, N cycles. carbonate lens located directly over the LED. Opposite the Cycle Error ( C): An indication of cycle uniformity. The dier- emitter is the integrated detector circuit. This IC consists ence between an observed shaft angle which gives rise to of multiple sets of photodetectors and the signal process- one electrical cycle, and the nominal angular increment of ing circuitry necessary to produce the digital waveforms. 1/N of a revolution. The codewheel rotates between the emitter and detector, Pulse Width (S): The number of electrical degrees that an causing the light beam to be interrupted by the pattern of output is high during 1 cycle. This value is nominally spaces and bars on the codewheel. 180e or 1/2 cycle. The photodiodes which detect these interruptions are Pulse Width Error ( P): The deviation, in electrical degrees, of arranged in a pattern that corresponds to the radius and the pulse width from its ideal value of 180e. design of the code-wheel. These detectors are also spaced such that a light period on one pair of detectors corre- State Width (S): The number of electrical degrees between a sponds to a dark period on the adjacent pair of detectors. transition in the output of channel A and the neighboring transition in the output of channel B. There are 4 states per The photodiode outputs are then fed through the signal cycle, each nominally 90e. processing circuitry resulting in A, A-bar, B, B-bar, I and I- bar. Comparators receive these signals and produce the State Width Error ( S): The deviation, in electrical degrees, of nal output for channels A and B. Due to this integrated each state width from its ideal value of 90e. phasing technique, the digital output of channel A is Phase Error ( ): The deviation of the phase from its ideal in quadrature with that of channel B (90 degrees out of value of 90e. phase). Direction of Rotation: When the codewheel rotates in the clockwise direction viewing from top of the module (di- rection from V to G), channel A will lead channel B. If the codewheel rotates in the opposite direction, channel B will lead channel A. Optical Radius (Rop): The distance from the codewheels cen- ter of rotation to the optical center (O.C) of the encoder module. Index Pulse Width (Po): The number of electrical degrees that an index is high during one full shaft rotation. This value is nominally 90 e or 1/4 cycle. 2