HEDB-9040 and HEDB-9140 Three Channel Optical Incremental Encoder Modules Bundle With Codewheel Data Sheet Description Features The HEDB-9040 and HEDB-9140 series are three channel Two Channel Quadrature Output with Index Pulse optical incremental encoder modules off ered with a Resolution from 100 CPR Up To 1024 CPR (Counts Per codewheel. When used with a codewheel, these low cost Revolution) modules detect rotary position. Each module consists of Low Cost a lensed LED source and a detector IC enclosed in a small plastic package. Due to a highly collimated light source Easy to Mount and a unique photodetector array, these modules are No Signal Adjustment required extremely tolerant to mounting misalignment. Small Size The HEDB-9040 and 9140 has two channel quadrature Operating Temperature: -40C to 100C outputs plus a third channel index output. This index TTL Compatible output is a 90 electrical degree high true index pulse which is generated once for each full rotation of the codewheel. Single 5V Supply The HEDB-9040 is designed for use with a HEDS-6140 Applications codewheel which has an optical radius of 23.36 mm (0.920 inch). The HEDB-9140 is designed for use with a The HEDB-9040 and 9140 provide sophisticated motion HEDS-5140 codewheel which has an optical radius of control detection at a low cost, making them ideal for high 11.00 mm (0.433 inch). volume applications. Typical applications include printers, plotters, tape drives, and industrial and factory automa- The quadrature signals and the index pulse are accessed tion equipment. through fi ve 0.025 inch square pins located on 0.1 inch Note: Avago Technologies encoders are not recommended for use in (pitch) centers. safety critical applications. Eg. ABS braking systems, power steering, life support systems and critical care medical equipment. Please contact sales representative if more clarifi cation is needed.Theory of Operation The HEDB-9040 and 9140 is emitter/detector modules. Cycle Error (C): An indication of cycle uniformity. The diff er- Coupled with a codewheel, these modules translate ence between an observed shaft angle which gives rise to the rotary motion of a shaft into a three-channel digital one electrical cycle, and the nominal angular increment of output. 1/N of a revolution. As seen in Figure 1, the modules contain a single Light Pulse Width (P): The number of electrical degrees that an Emitting Diode (LED) as its light source. The light is col- output is high during 1 cycle. This value is nominally 180e limated into a parallel beam by means of a single poly- or 1/2 cycle. carbonate lens located directly over the LED. Opposite the Pulse Width Error (P): The deviation, in electrical degrees, of emitter is the integrated detector circuit. This IC consists the pulse width from its ideal value of 180e. of multiple sets of photodetectors and the signal process- ing circuitry necessary to produce the digital waveforms. State Width (S): The number of electrical degrees between a transition in the output of channel A and the neighboring The codewheel rotates between the emitter and detector, transition in the output of channel B. There are 4 states per causing the light beam to be interrupted by the pattern of cycle, each nominally 90e. spaces and bars on the codewheel. Phase ( ): The number of electrical degrees between the The photodiodes which detect these interruptions are center of the high state of channel A and the center of the arranged in a pattern that corresponds to the radius and high state of channel B. design of the code-wheel. These detectors are also spaced such that a light period on one pair of detectors corre- This value is nominally 90e for quadrature output. sponds to a dark period on the adjacent pair of detectors. Phase Error (): The deviation of the phase from its ideal The photodiode outputs are then fed through the signal value of 90e. processing circuitry resulting in A, Abar, B, Bbar, I and Direction of Rotation: When the codewheel rotates in the Ibar. Comparators receive these signals and produce clockwise direction viewing from top of the module the fi nal outputs for channels A and B. Due to this inte- (direction from V to G), channel A will lead channel B. If grated phasing technique, the digital output of channel the codewheel rotates in the opposite direction, channel A is in quadrature with that of channel B (90 degrees out B will lead channel A. of phase). Optical Radius (Rop): The distance from the codewheels Defi nitions center of rotation to the optical center (O.C) of the encoder module. Note: Refer to Figure 2 Index Pulse Width (Po): The number of electrical degrees that Count (N): The number of bar and window pairs or counts an index is high during one full shaft rotation. This value is per revolution (CPR) of the codewheel. nominally 90e or 1/4 cycle. One Cycle (C): 360 electrical degrees (e), 1 bar and window pair. Specifi cation One Shaft Rotation: 360 mechanical degrees, N cycles. For encoder electrical, mechanical specifi cations, code- wheel technical specifi cations and additional informations Position Error (): The normalized angular diff erence please refer to : between the actual shaft position and the position indicated by the encoder cycle count. HEDS-9040 /9140 datasheet. HEDS/HEDG/HEDM 51xx/61xx Codewheel Datasheet 2