Mitutoyo Corporation

Other

Karl G Masreliez

Michael Nahum

Nils Ingvar Andermo

Kim W Atherton

Patrick H Mawet

Kurt E Steinke

An absolute position transducer system has two members movable relative to each other and includes a code track transducer and at least one fine wavelength transducer. The code track is arranged to form a sequential pattern of base-N code words, where N is greater than two (i.e., non-binary). Each sequential non-binary code word identifies an absolute position of one member with respect to the other at a first resolution. Alternatively, the code track is arranged to form a pseudo-random non-binary code word pattern. In this case, the transducer system compares a non-binary code word with a look-up table to determine an absolute position of one member with respect to the other at a first resolution. In order to generate a non-binary code word pattern, code track transducer employs different-sized flux disrupters, different-sized flux enhancers, or a combination of flux disrupters and enhancers.

Absolute position transducer having a non-binary code-track-type scale

A high-accuracy inductive absolute position transducer system has two members movable relative to each other and includes a code track transducer and may include a fine track transducer. The code track transducers includes a code track transmitter winding and at least one set of code track receiver windings. Each set of code track receiver windings includes n balanced pairs. Each balanced pair extends along the measuring axis and includes a positive polarity winding and a negative polarity winding. A code track has a plurality of flux modulator zones distributed along the measuring axis. Flux modulators are formed in at least some of the flux modulator zones. A signal generating and processing circuit is connected to the transmitter winding and each balanced pair. The code track transmitter winding and each balanced pair form an inductive coupling. The flux modulators modulate the inductive coupling between each balanced pair and the code track transmitter winding based on the relative position between the read head member and the scale member. The flux modulators are distributed along the measuring axis such that each pair of adjacent flux modulator zones forms one of a set of output states in an overlying balanced pair. The pairs of adjacent flux modulator zones form a series of code elements extending along the measuring axis such that each set of m adjacent code elements forms a unique codeword. Each unique codeword defines an absolute position of the read head member relative to the scale member to a first resolution.

Induced current absolute position transducer method using a

An electronic linear scale having a reduced offset position transducer that uses at least one coupling loop on a scale to inductively couple a transmitter winding on a read head to one or more receiver windings on the read head. The transmitter winding generates at least one primary magnetic field. The transmitter winding is inductively coupled to first loop portions of the coupling loops by the primary magnetic field. Second loop portions of the coupling loops generate secondary magnetic fields. Each receiver winding is inductively coupled to the second loop portions of the coupling loops by the secondary magnetic fields. At least one of the transmitter winding or the receiver windings is formed in a periodic pattern complementary to the dimensions of the coupling loops. Prescribed winding configurations are used to reduce the effects of extraneous inductive coupling in the device. Depending on the relative position between the read head and the scale, the receiver windings inductively couple to the second loop portions of the coupling loops to various degrees. A compact, high accuracy, high resolution inductive position sensor results. Low power operation is possible.

Electronic linear scale using a reduced offset high accuracy induced

A self-calibrating position transducer system and method uses the position transducer itself as a position reference during calibration, thus eliminating using an external reference during calibration. The transducer signals are sampled at a plurality of evenly-spaced positions within each sampled scale wavelength, using the transducer itself as a position reference. The calibration values for the DC signal offsets, the amplitudes and non-orthogonality of the fundamental signals, the amplitudes of the signal harmonic components and position offsets are then determined using Fourier analysis techniques. The transducer signals are corrected using the determined calibration values, which are in turn used to revise the stored calibration values in anticipation of the next calibration operation. The self-calibrating position transducer uses the stored calibration values to enhance its accuracy.

Self-calibrating position transducer system and method

An inductive transducer system for use in high accuracy applications such as linear or rotary encoders, employs two members movable relative to each other. A first, active member induces eddy currents in a second, passive member that lacks a power source or electrical wires connected thereto. The first, active member contains both a transmitter for generating a magnetic field and a receiver for receiving the field. The receiver has a plurality of symmetric loops. Electronic circuitry coupled to the receiver evaluates the relative position between the two members as the passive member disrupts the magnetic field received by the receiver. The inductive transducer can be readily manufactured using known printed circuit board technology, and is substantially immune to contamination by particles, including ferromagnetic particles, oil, water and other fluids. A pulse-driven drive circuit allows the inductive transducer to consume little power, and thus allows the transducer to be readily incorporated into hand-held, battery-powered measurement tools.

Induced current position transducer having a low power electronic circuit

A reduced offset position transducer uses at least one coupling loop on a scale to inductively couple a transmitter winding on a read head to one or more receiver windings on the read head. The transmitter winding generates at least one primary magnetic field. The transmitter winding is inductively coupled to first loop portions of the coupling loops by the primary magnetic field. Second loop portions of the coupling loops generate secondary magnetic fields. Each receiver winding is inductively coupled to the second loop portions of the coupling loops by the secondary magnetic fields. At least one of the transmitter winding or the receiver windings is formed in a periodic pattern complementary to the dimensions of the coupling loops. Prescribed winding configurations are used to reduce the effects of extraneous inductive coupling in the device. Depending on the relative position between the read head and the scale, the receiver windings inductively couple to the second loop portions of the coupling loops to various degrees. A compact, high accuracy, high resolution inductive position sensor results. Low power operation is possible.

Reduced offset high accuracy induced current position transducer

An electronic linear scale, which uses an induced current position transducer, includes a slider assembly mounted adjacent to an elongated beam. The slider assembly is mounted on one mounting member of a device such as a machine tool. The elongated beam is mounted on a second mounting member of the device. The first and second mounting members move relative to each other. The position of the slider assembly on the beam is indicative to of the position between the first and second mounting members. Relative movement is determined by an inductive read head mounted on the slider assembly that couples to flux modulators on the beam. The read head includes a transmitter winding and a pair of receiver windings, preferably fabricated in a planar form, carried by a common printed circuit board. The flux modulators, which can include flux disrupters and/or flux enhancers, are carried by the beam and modulate the magnetic fields produced by the transmitter. Thus, the receiver windings produce output voltages corresponding to the overlap between the modulators and the receiver windings. Signal processing electronics are connected to the read head and determine the relative positions of the first and second mounting members by monitoring the output of the receiver windings. A digital display displays the determined position. The relatively insensitive nature of the induced current position transducer to contaminants allows the linear scale to function with improved reliability when operating in industrial environments. Low power operation of the linear scale is possible.

Electronic linear scale using a self-contained, low-power inductive

A pitch-compensated induced current position transducer includes a scale having a plurality of scale elements arranged along a measuring axis and a read head positioned adjacent to and movable relative to the scale. The read head has a transmitter winding that generates a changing magnetic field and at least one receiver winding. One of the transmitter winding and receiver winding is formed from a spatially modulated section having an associated phase. The spatially modulated section has flux coupling areas distributed relative to a plurality of polarity zones. The spatially modulated section has at least one pitch balancing section. In one type of pitch balancing section the positive polarity winding loops and the negative polarity winding loops have their centroid axes aligned. The total flux coupling area in at least one polarity zone may optionally be different than the total flux coupling area in an adjacent polarity zone while the total negative flux coupling area remains equal to the total positive flux coupling area. In general, the pitch balancing sections are configured so that the overall centroids of all spatially modulated sections are aligned along the measuring axis. The distribution of the flux coupling area may be symmetrical.

Pitch-compensated induced current position transducer

An electronic caliper using a low power induced current position transducer includes a slider assembly mounted on an elongated beam with first and second measuring jaws projecting from the main beam and slider assembly. The position of the slider assembly on the beam is indicative of the distance between the first and second jaws. A depth bar is also attached to, and projects from, the slider assembly. Relative movement between the measuring jaws is determined by an inductive read head mounted on the slider assembly that couples to flux modulators on the beam. The read head includes a transmitter winding and a pair of receiver windings carried by a common printed circuit board. The flux modulators, which can include both flux disrupters and flux enhancers, are carried by the beam and modulate the magnetic fields produced by the transmitter. Thus, the receiver windings produce output voltages corresponding to the overlap between the modulators and the receiver windings. Signal processing electronics are connected to the read head and determine the relative positions of the jaws by monitoring the output of the receiver windings. A digital display displays the determined position. In one embodiment, either flux enhancers or flux disrupters are used. In another embodiment, both flux disrupters and flux enhancers are used. The relatively insensitive nature of the low power induced current position transducer to industrial contaminants allows the caliper to function with improved reliability when operating in traditional shop environments.

Electronic caliper using a self-contained, low power inductive position

An induced current position transducer has a multi-tap winding. The multi-tap winding allows for digital interpolation of position to a small fraction of a wavelength, thereby reducing the amount of analog interpolation performed by the transducer electronics. In addition, a multi-tap receiver winding enhances the total output signal strength, thereby allowing a smaller receiver winding length along the direction of the measurement axis. Furthermore, a multi-tap receiver winding exhibits low impedance, thereby improving the output signal time constant. The multi-tap receiver winding of this invention comprises a plurality of receiver winding loops offset with respect to each other along the measuring axis, and electrically connected in series. Preferably, the signal contributions of each loop combine to form a 'vector circle'.

Inductive position transducer having a multi-tap receiver winding

An electronic caliper having a reduced offset position transducer that uses two sets of coupling loops on a scale to inductively couple a transmitter winding on a read head on a slide to one or more receiver windings on the read head. The transmitter winding generates a primary magnetic field. The transmitter winding is inductively coupled to first loop portions of first and second sets of coupling loops by a magnetic field. Second loop portions of the first and second sets of coupling loops are interleaved and generate secondary magnetic fields. A receiver winding is formed in a periodic pattern of alternating polarity loops and is inductively coupled to the second loop portions of the first and second sets of coupling loops by the secondary magnetic fields. Depending on the relative position between the read head and the scale, each polarity loop of the receiver winding is inductively coupled to a second loop portion of either the first or second set of coupling loops. The relative positions of the first and second loop portions of the first and second sets of coupling loops are periodic and dependent on the relative position of the coupling loops on the scale.

Electronic caliper using a reduced offset induced current position

An electronic linear tape measure using a low power induced current position transducer. The tape measure includes an enclosure case with a lateral slot through which the tape blade can be pulled. The tape blade is wound inside the enclosure case on a tape reel which is mounted on an axis support that has a spring loaded rewind mechanism. Also included are a tape lock, a keypad for various functions, and a conventional LCD display for displaying measured lengths. The signal processing and display electronics of the electronic tape measure are connected to the active portion of the transducer. The display provides an indication of the relative position between the elements of the transducer that coincides with the length of tape that has been pulled from the enclosure case. The relatively insensitive nature of the low power induced current position transducer to contaminants, tape damage and mechanical shock allows construction of an electronic tape measure with the preferred, historically proven, form that functions with greatly improved reliability when operating in a traditional environment. Additionally, the low power consumption of the induced current position transducer significantly increases the practicality of an electronic tape measure.

Electronic linear tape measure using a low power induced current

An inductive absolute position transducer system, usable in high accuracy applications such as linear encoders, has two members movable relative to each other and includes three inductive position transducers. Each inductive position transducer includes at least one transmitter winding for generating a magnetic field and two or more receiver windings for receiving the magnetic field. Each inductive position transducer also includes a plurality of flux modulators which modulate the magnetic field generated by the transmitter winding. Each receiver winding has a plurality of symmetric loops arranged along a measurement axis. The receiver windings of two of the inductive position transducers define two wavelengths that are similar to each other, but not equal. Thus, a phase relationship between the inductive position transducers has a wavelength much longer than the wavelength of either of the two inductive position transducers. An electronic circuit coupled to the inductive position transducers determines the absolute position between the two members. In an alternative embodiment, the inductive absolute position transducer includes only one inductive position transducer, having a fine wavelength. The inductive absolute position transducer includes one or more inductive transducers with a relatively coarse wavelength. An electronic circuit coupled to the inductive position transducers determines the absolute position between the two members, first identifying a coarse absolute position measurement along the measuring axis using the relatively coarse wavelength transducer, and refining this position measurement using information from the inductive position transducer having a fine wavelength.

Multi-scale induced current absolute position transducer

A high-accuracy inductive absolute position transducer system has two members movable relative to each other and includes a code track transducer and may include a fine track transducer. The code track transducer includes a code track transmitter winding and at least one set of code track receiver windings. Each set of code track receiver windings includes n balanced pairs. Each balanced pair extends along the measuring axis and includes a positive polarity winding and a negative polarity winding. A code track has a plurality of flux modulator zones distributed along the measuring axis. Flux modulators are formed in at least some of the flux modulator zones. A signal generating and processing circuit is connected to the transmitter winding and each balanced pair. The code track transmitter winding and each balanced pair form an inductive coupling. The flux modulators modulate the inductive coupling between each balanced pair and the code track transmitter winding based on the relative position between the read head member and the scale member. The flux modulators are distributed along the measuring axis such that each pair of adjacent flux modulator zones forms one of a set of output states in an overlying balanced pair. The pairs of adjacent flux modulator zones form a series of code elements extending along the measuring axis such that each set of m adjacent code elements forms a unique codeword. Each unique codeword defines an absolute position of the read head member relative to the scale member to a first resolution.

Induced current absolute position transducer using a code-track-type

A speed sensor for a ship, more particularly, a thin speed sensor which can be mounted in the hull of the ship and remain flush with the outer surface of the hull. The transducer assembly for the speed sensor is composed of two thin piezoelectric transducers mounted in a spacer plate that locates them in an exact position relative to each other. A baseplate and a coverplate are affixed by appropriate adhesive techniques to each side of the transducers to create a single transducer assembly. Holes through the baseplate and spacer plate permit electrical contact to each side of the transducers so that they may be stimulated to generate acoustic waves. The entire transducer assembly is significantly thinner than the hulls of most watercraft. Thus, a large hole completely through the hull is not necessary. Rather, a shallow recess approximately equal to the thickness of the transducer assembly is made in the hull to countersink the transducer assembly flush with the hull. A small hole to permit the electrical connections to be made to the transducer assembly can be made in the hull if desired. This invention provides for the easy manufacture and mass production of a thin transducer assembly which may be used on a wide variety of watercraft, including sailboards, waterskis, row boats, as well as speedboats and larger ships.

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Bellevue, WA, United States of America

Karl G Masreliez