Abstract: An encoder system for detecting a movement of a part of a motor system is disclosed. The encoder system may comprise a sensor array, a detection controller, and an error detector circuit. The sensor array may be configured to generate first and second periodic signals in accordance to the movement of the part of the motor system. The detection controller may be coupled to the sensor array and may be configured to generate a periodic control signal derived from at least one of the first and second periodic signals. The error detector circuit may be coupled to the sensor array and the detection controller and configured to generate an error signal when at least one of the first and second periodic signals is outside a predetermined range when the periodic control signal is triggered.

Abstract: An LED current regulator can regulate an LED current of an encoder system. The LED current regulator may comprise a first analog multiplier and a second analog multiplier. Each of the first and second analog multipliers may be configured to receive respective photodetector output signals, characterized by a peak-to-peak voltage, Vpp, and may be configured to generate respective first and second multiplier output signals. The first and second multiplier output signals may be combined to produce a first DC level, which may be representative of the peak-to-peak voltage, Vpp, of the photodetector output signals.

Abstract: An offset correction system for correcting signal offset of an encoder. The offset correction system may include a light emitter, an encoder disk, a reticle, a light detector; an offset detection circuit and an offset correction circuit. The offset detection circuit may comprise a comparator and an offset detector configured to receive sinusoidal output signals from the light detector and a reference signal to create digital pulses for determining the signal offset. The offset correction circuit may be configured to apply a gain to correct the offset output signal. The offset correction may be implemented in real time mode.

Abstract: An LED current regulator can regulate an LED current of an encoder system. The LED current regulator may comprise a first analog multiplier and a second analog multiplier. Each of the first and second analog multipliers may be configured to receive respective photodetector output signals, characterized by a peak-to-peak voltage, Vpp, and may be configured to generate respective first and second multiplier output signals. The first and second multiplier output signals may be combined to produce a first DC level, which may be representative of the peak-to-peak voltage, Vpp, of the photodetector output signals.

Abstract: An offset correction system for correcting signal offset of an encoder. The offset correction system may include a light emitter, an encoder disk, a reticle, a light detector; an offset detection circuit and an offset correction circuit. The offset detection circuit may comprise a comparator and an offset detector configured to receive sinusoidal output signals from the light detector and a reference signal to create digital pulses for determining the signal offset. The offset correction circuit may be configured to apply a gain to correct the offset output signal. The offset correction may be implemented in real time mode.

Abstract: A method for interpolating an encoded signal of encoders is disclosed. The first step may include generating four first stage signals having a first frequency that are 45 degrees out of phase. The four signals may then be multiplied to obtain a plurality of second stage signals that are 90 degrees out of phase having a second frequency two times the first frequency. The second stage signals may then go through further computation to obtain a plurality of third stage signals that are 45 degrees out of phase. The third stage signals may be further adapted for further multiplication to obtain higher levels of interpolation. Interpolators and optical encoders characterized by the interpolation capability are also disclosed.

Abstract: A method for interpolating an encoded signal of encoders is disclosed. The first step may include generating four first stage signals having a first frequency that are 45 degrees out of phase. The four signals may then be multiplied to obtain a plurality of second stage signals that are 90 degrees out of phase having a second frequency two times the first frequency. The second stage signals may then go through further computation to obtain a plurality of third stage signals that are 45 degrees out of phase. The third stage signals may be further adapted for further multiplication to obtain higher levels of interpolation. Interpolators and optical encoders characterized by the interpolation capability are also disclosed.

Abstract: Disclosed are various embodiments of interpolation circuits for use in conjunction with optical encoders. The analog output signals provided by incremental or absolute motion encoders are provided to an interpolation circuit, which is capable of providing high interpolation factor output signals having high timing accuracy. The disclosed interpolation circuits may be implemented using CMOS or BiCMOS processes without undue effort.

Abstract: Disclosed are various embodiments of interpolation circuits for use in conjunction with optical encoders. The analog output signals provided by incremental or absolute motion encoders are provided to an interpolation circuit, which is capable of providing high interpolation factor output signals having high timing accuracy. The disclosed interpolation circuits may be implemented using CMOS or BiCMOS processes without undue effort.

Abstract: According to one embodiment, there is provided an optical encoder having a photodetector array comprising motion detection photodetectors and at least one reference photodetector vertically offset from the motion detection photodetectors. The output signal generated by the at least one reference photodetectors is employed to correct undesired variations in the amplitudes of the output signals generated by the motion detection photodetectors. Such variations typically arise from various mechanical and optical misalignments in the optical encoder, and are compensated for by using the reference output signal to add to or subtract from, as required, the amplitudes of motion detection output signals.

Abstract: According to one embodiment, there is provided an optical encoder having a photodetector array comprising motion detection photodetectors and at least one reference photodetector vertically offset from the motion detection photodetectors. The output signal generated by the at least one reference photodetectors is employed to correct undesired variations in the amplitudes of the output signals generated by the motion detection photodetectors. Such variations typically arise from various mechanical and optical misalignments in the optical encoder, and are compensated for by using the reference output signal to add to or subtract from, as required, the amplitudes of motion detection output signals.

Abstract: In one embodiment, an optical encoder includes a light source, a detector array and a code member. The detector array is positioned in spaced-apart relation to the light source and includes at least one detector set. Each of the at least one detector sets includes a plurality of detector elements. The code member 1) is positioned between the light source and the detector array, 2) is moveable with respect to the detector array along a displacement direction, and 3) defines a plurality of circular or elliptical openings through which light emitted by the light source is filtered to produce light spots that travel across the detector array as the code member moves with respect to the detector array. Other embodiments are also disclosed.

Abstract: An optical encoder includes a coding element having a track with a track pattern that comprises multiple optically distinguishable sections. The optical encoder compares photodetector outputs with transition-specific thresholds that correspond to transitions between the optically distinguishable sections of the track. The comparisons are used to determine when the transition between two optically distinguishable sections of the track has passed the photodetector. Knowledge of the transition between two optically distinguishable sections is then translated into digital position information.

Abstract: In one embodiment, an optical encoder includes a code member, a light source, and a detector array. The code member has a plurality of reflectors thereon; and the light source is positioned to illuminate an area of the code member that includes at least one of the reflectors. The detector array includes at least one detector set, each of which includes a plurality of detector elements. The code member and the detector array are moveable with respect to one another along a displacement direction, and as the code member moves with respect to the detector array, the reflectors on the code member reflect light emitted by the light source to produce circular or elliptical light spots that travel across the detector array.

Abstract: An optical encoder includes a coding element having a track with a track pattern that comprises multiple optically distinguishable sections. The optical encoder compares photodetector outputs with transition-specific thresholds that correspond to transitions between the optically distinguishable sections of the track. The comparisons are used to determine when the transition between two optically distinguishable sections of the track has passed the photodetector. Knowledge of the transition between two optically distinguishable sections is then translated into digital position information.