AEDR-8300-1Wx Encoders Reflective Surface Mount Optical Encoder Data Sheet Description Features The AEDR-8300-1Wx is the smallest optical encoder Reflective technology employing reflective technology for motion control Surface mount leadless package purposes. The encoder houses an LED light source and a Two channel quadrature outputs for direction sensing photo-detecting circuitry in a single package. TTL compatible output The AEDR-8300-1Wx offers two-channel quadrature Single 3.3 V to 5 V supply digital outputs. Being TTL compatible, the outputs of the AEDR-8300-1Wx can be interfaced directly with most -20 C to 85 C absolute operating temperature of the signal processing circuitries. Hence the encoder Encoding resolution: 212 (lines/inch) or 8.35 (lines/mm) provides great design-in flexibility and easy integration into existing systems. The AEDR-8300-1Wx could yields Applications encoding resolution at 212 lines per inch (LPI) which is Ideal for high volume applications: 8.35 lines per mm. Printers The AEDR-8300-1Wx provides motion sensing at a com- petitive cost, making it ideal for high volume applications. Copiers Its small size and surface mount package make it ideal for Card readers many consumer products, particularly where space and Scanners weigh are primary design constraint. Cameras Motor Solutions Automated Wheel-chair Vending Machines Low Servo Systems ATM Machines Textile Machines Industrial Sewing Machines Consumer Product ApplicationsTheory of Operation Definitions The AEDR-8300-1Wx combines an emitter and a detector State Width (S): The number of electrical degrees between in a single surface mount leadless package. When used a transition in Channel A and the neighboring transition with a codewheel or linear codestrip, the encoder trans- in Channel B. There are 4 states per cycle, each nominally lates rotary or linear motion into digital outputs. As seen 90e. in the block diagram, the AEDR-8300-1Wx consists of State Width Error (S): The deviation of state width, in elec- three major components: a light emitting diode (LED) trical degree, from its ideal value of 90e. light source, a detector IC consisting photodiodes and lens to focus light beam from the emitter as well as light Phase (): The number of electrical degrees between the falling on the detector. center of high state of Channel A and the center of high state of Channel B. Nominally 90e. Block Diagram of AEDR-8300-1Wx Phase Error (): The deviation of phase, in electrical degree, from its ideal value of 90e. V LED R CODEWHEEL Pulse Width (P): The duration of high state of the output, GND or CODESTRIP in electrical degree, within one cycle. Nominally 180e or half a cycle. V CC CH A Pulse Width Error (P): The deviation of pulse width, in elec- SIGNAL trical degree, from its ideal value of 180e. CH B PROCESSING CIRCUITRY Count (N): The number of window and bar pair per revolu- tion (CPR) of codewheel. For linear codestrip, defined as GND the number of window and bar pair per unit length (lines per inch LPI or lines per mm LPmm ). One Cycle (C): 360 electrical degrees (e). Equivalent to one window and bar pair. The operation of the encoder is based on the principle of One Shaft Rotation: 360 mechanical degrees. Also equiva- optics where the detector photodiodes sense the absence lent to N counts (codewheel only). and presence of light. In this case, the rotary/linear motion of an object being monitored is converted to equiva- Line Density: The number of window and bar pair per unit lent light pattern via the use of codewheel/codestrip. As length, expressed in either lines per inch (LPI) or lines per shown in the above diagram, the reflective area (window) mm (LPmm). of the codewheel (or codestrip) reflects light back to the Optical radius (Rop): The distance between the codewheel photodetector IC, whereas no light is reflected by the center and the centerline between the two domes of the non-reflective area (bar). An alternating light and dark encoder. patterns corresponding to the window and bar fall on the photodiodes as the codewheel rotates. The moving Gap (G): The distance from surface of the encoder to the light pattern is exploited by the detector circuitry to surface of codewheel or codestrip. produce digital outputs representing the rotation of the Radial and Tangential Misalignment Error (E , E ): For rotary R T codewheel. When the codewheel is coupled to a motor, motion, mechanical displacement in the radial and tan- the encoder outputs are then a direct representation of gential directions relative to the nominal alignment. the motor rotation. The same concept applies to the use of a codestrip to detect linear motion. Angular Misalignment Error (E ): Angular displacement of A the encoder relative to the tangential line. Specular Reflectance (R ): The amount of incident light f reflected by a surface. Quantified in terms of the per - centage of incident light. A spectrometer can be used to measure specular reflectance of a surface (contact factory for more information). 2