Abstract: A touch probe circuit comprises a displacement sensor having a sensor signal responsive to touch probe stylus displacement, an offset compensation controller, and a difference amplifier. The offset compensation controller provides a varying offset compensation signal to compensate drift in a rest-state signal component of the sensor signal. The difference amplifier inputs the offset compensation signal and the sensor signal and amplifies the difference therebetween to provide an offset compensated displacement signal, which is output to a touch trigger signal generating circuit that provides a touch signal when the stylus touches a workpiece, and is also output to the offset compensation controller. The offset compensation controller portion provides a feedback loop that inputs the offset compensated displacement signal and outputs a responsive low pass filtered offset compensation signal to the difference amplifier, in order to provide the offset compensated displacement signal.

Abstract: A touch probe circuit comprises a displacement sensor having a sensor signal responsive to touch probe stylus displacement, an offset compensation controller, and a difference amplifier. The offset compensation controller provides a varying offset compensation signal to compensate drift in a rest-state signal component of the sensor signal. The difference amplifier inputs the offset compensation signal and the sensor signal and amplifies the difference therebetween to provide an offset compensated displacement signal, which is output to a touch trigger signal generating circuit that provides a touch signal when the stylus touches a workpiece, and is also output to the offset compensation controller. The offset compensation controller portion provides a feedback loop that inputs the offset compensated displacement signal and outputs a responsive low pass filtered offset compensation signal to the difference amplifier, in order to provide the offset compensated displacement signal.

Abstract: A caliper including a scale member, a slider, a slider displacement sensor and a force sensing arrangement. The force sensing arrangement is configured to provide a signal indicative of a measurement force, and includes elements fabricated on the same circuit board as the slider displacement sensor. In one implementation, the force sensing arrangement includes drive and sense coils that are fabricated in one or more metal layers of the circuit board. A signal modulating element (e.g., a metal core) is also included which is attached to a force actuator which moves in accordance with the amount of measurement force that is being applied. The force actuator moves relative to the linearly displaced coils and the attached signal modulating element affects the inductive coupling between the coils. The resulting signals from the coils may be utilized to determine the position of the signal modulating element and the corresponding measurement force.

Abstract: A caliper including a scale member, a slider, a slider displacement sensor and a force sensing arrangement. The force sensing arrangement is configured to provide a signal indicative of a measurement force, and includes elements fabricated on the same circuit board as the slider displacement sensor. In one implementation, the force sensing arrangement includes drive and sense coils that are fabricated in one or more metal layers of the circuit board. A signal modulating element (e.g., a metal core) is also included which is attached to a force actuator which moves in accordance with the amount of measurement force that is being applied. The force actuator moves relative to the linearly displaced coils and the attached signal modulating element affects the inductive coupling between the coils. The resulting signals from the coils may be utilized to determine the position of the signal modulating element and the corresponding measurement force.

Abstract: A multimode electronic measuring instrument is provided that includes a ratiometric mode of operation. During the ratiometric mode, a desired dimension is established as a stored reference dimension Xref. After the reference dimension is stored in memory, subsequent ratiometric measurement readouts will equal a current measurement distance Xcurr divided by the reference dimension Xref. A persistent number of decimal places used to the right of the decimal point as seen on a display is determined based on a current reference dimension Xref, an increment used for the least significant digit, and an internal measurement resolution of the multimode electronic measuring instrument.

Abstract: A multimode electronic measuring instrument is provided that includes a ratiometric mode of operation. During the ratiometric mode, a desired dimension is established as a stored reference dimension Xref. After the reference dimension is stored in memory, subsequent ratiometric measurement readouts will equal a current measurement distance Xcurr divided by the reference dimension Xref. A persistent number of decimal places used to the right of the decimal point as seen on a display is determined based on a current reference dimension Xref, an increment used for the least significant digit, and an internal measurement resolution of the multimode electronic measuring instrument.

Abstract: A system and method for real time calibration of a quadrature encoder. Errors from sources such as signal offsets, amplitude mismatches and phase errors are addressed. In one embodiment, the errors are addressed by determining and applying a dynamic operational set of calibration parameters. The process for determining the operational calibration parameters involves minimizing a variation metric that indicates the variations of the magnitudes of a set of corrected vectors Ci?. The corrected vectors Ci? are defined by using the calibration parameters to provide corrected vector components (Ati?, Bti?) that correspond to a current operational set of quadrature signal samples comprising at least four respective quadrature signal samples (Ati, Bti) having spatial phase angles ?ti that are distributed over a significant portion of 360 degrees. For well chosen calibration parameters, the resulting corrected vectors define a well-centered circle and the variation metric is minimized.

Abstract: A high speed quadrature counter for use with a displacement measuring device is disclosed. The counter provides high speed counting by partitioning the tracking counter into a small fast tracking counter portion for the LSBs and a larger slow tracking counter portion for the MSBs. The fast tracking counter portion outputs a smaller number of bits according to a fast clock rate, while the slow tracking counter portion outputs a larger number of bits to update the remainder of the position at a slower clock rate. In various embodiments, the counter provides a corrected position value that has an effective timing within a few fast clock cycles of the time of the latch trigger signal. A corrected latched position circuit corrects an error that may otherwise be produced by the partitioning and the different clock rates of the fast and slow tracking counter portions.

Abstract: A system and method for real time calibration of a quadrature encoder. Errors from sources such as signal offsets, amplitude mismatches and phase errors are addressed. In one embodiment, the errors are addressed by determining and applying a dynamic operational set of calibration parameters. The process for determining the operational calibration parameters involves minimizing a variation metric that indicates the variations of the magnitudes of a set of corrected vectors Ci?. The corrected vectors Ci? are defined by using the calibration parameters to provide corrected vector components (Ati?, Bti?) that correspond to a current operational set of quadrature signal samples comprising at least four respective quadrature signal samples (Ati, Bti) having spatial phase angles ?ti that are distributed over a significant portion of 360 degrees. For well chosen calibration parameters, the resulting corrected vectors define a well-centered circle and the variation metric is minimized.

Abstract: A method for connecting optical signals carried by optical fibers between an optical encoder readhead and an optical signal processing IC having a plurality of photodetector portions arranged in a photodetector configuration. The optical signal processing IC is fixed to a substrate at a first position and orientation. Then, a reference-surface block including at least one reference surface is fixed to the substrate in a second orientation and position based on the first position and orientation. A fiber-optic end piece is provided, which has at least one corresponding-reference surface and a plurality of optical fiber locating features that are arranged relative to the corresponding-reference surface. A plurality of the optical fibers are fixed to the plurality of optical fiber locating features to provide a coupling configuration of optical fiber ends that nominally matches the photodetector configuration.

Abstract: Systems and methods are provided for calibrating a sample delay time between a position request time from a host computer and a position encoder sample time. The position encoder includes a readhead with a transducer and transducer electronics, and encoder interface electronics which exchange data and commands with the readhead and with the host computer. The transducer electronics may lack a clock capable providing a sufficiently consistent sample delay time. To provide a consistent sample delay the interface electronics measures an inherent sample delay time based on signals from the readhead during a calibration mode. The difference between the inherent delay time and the desired delay time is saved and inserted by the interface electronics during position measurement such that the calibrated sample delay time is consistently the desired sample delay time.