Mitutoyo Corporation

Mitsubishi Denki Kabushiki Kaisha

Tetsuro Kiriyama

Toru Yaku

Toshiharu Miyata

Nobuyuki Hayashi

Kouji Sasaki

Toshihiko Aoki

Hiroaki Kawada

Ryuichi Koiso

Toshirou Yoshinaka

Mikiya Teraguchi

Yoshiaki Shiraishi

Toshitaka Shimomura

Mahito Unno

Shingo Nihommori

A correction value calculation method calculates correction values to correct the 2-phase sinusoidal signals (X, Y) output by the encoder, and includes: a polar coordinate calculation step for calculating, for N phase angles and the Lissajous radius corresponding to each phase angle in the Lissajous waveform drawn by the 2-phase sinusoidal signals, a squared radius, which is the square of the Lissajous radius corresponding to each phase angle; and a correction value calculation step for calculating, based on each phase angle and corresponding squared radius, at least a correction residual of an offset error of the signal X, a correction residual of an offset error of the signal Y, a correction residual of an amplitude ratio error of the signals X and Y, and a correction residual of a phase difference error between the signal X and the signal Y, and then calculating correction values based on the correction residuals.

Correction value calculation method, correction value calculation program, correction value calculation apparatus, and encoder

A resistor string outputs sixteen signals with a phase difference of 22.5&#xb0; by dividing voltage between two adjacent phases of a four-phase input signal with a phase difference of 2&#x3c0;/M (where M is an integer equal to or greater than 2), and by generating four signals with a delayed phase for each phase of the four-phase input signal. A switch portion selects four signals with a phase difference of 90&#xb0; from the sixteen signals. Amplifiers output each of the four signals, which are attenuated by dividing the voltage with the resistor string, as a four-phase output signal by amplifying each of the four signals such that an amplitude of the four signals matches the amplitude of the four-phase input signal.

Encoder having phase adjuster for offsetting phases of multi-phase input signal

A three-grating type photoelectric encoder includes a second grating formed on a scale and first and third gratings disposed on a side of a detector. A part of at least the first grating is shifted in a direction of a measurement axis by P/(2n) (wherein P is a grating pitch, n is the order of a harmonic component to be removed) in order to remove a harmonic component of the nth order. This encoder can be improved with high accuracy by removing harmonic components without increasing manufacturing costs.

Photoelectric encoder capable of effectively removing harmonic components

Two-phase sinusoidal signals QA, QB output from an encoder are interpolated by sample-and-hold (S/H) circuits and A/D conversion (ADC) circuits, and data D is output in accordance with a data request signal RQ from exterior. For this interpolation of encoder output, a direction discrimination up/down counter is arranged near a two-phase square-wave uniform pulse generating circuit, and the data D is latched and output using a signal which is obtained by delaying the data request signal RQ. This can reduce synchronization errors between the data request signal RQ from exterior and the interpolated data, with an improvement in dynamic precision.

Method and circuit for interpolating encoder output

A photoelectric encoder is provided, which emits light from a light source to a main scale and an index scale that can relatively move with respect to each other and obtains a light-receiving signal by interaction between the main scale and the index scale. The photoelectric encoder uses as the light source an incoherent semiconductor light source (white LED) in which a full width at half maximum of an emission spectrum is wider than that of a monochromatic semiconductor light source. Thus, it is possible to reduce an effect of a gap change on an output signal of the encoder and make positional adjustment easier, thereby improving misalignment characteristics.

Photoelectric encoder using an incoherent semiconductor light source

An offset error, an amplitude error, a phase error and a third harmonic component contained in two-phase sinusoidal signals are removed using relatively simple digital computations. An offset error contained in two-phase sinusoidal signals with a phase difference output from an encoder is detected and corrected. Then, an amplitude error contained in the offset-corrected two-phase sinusoidal signals is detected and corrected. Subsequently, a phase error contained in the amplitude-corrected two-phase sinusoidal signals is detected and corrected. Further, a third harmonic distortion contained in the phase-corrected two-phase sinusoidal signals is detected and corrected. Each correction step includes detecting an error from an ideal Lissajous waveform contained in the corrected two-phase sinusoidal signals, and adding the detected error to an accumulatively added last value to yield a new correction coefficient, thereby dynamically updating the correction coefficient.

Encoder output signal correction apparatus and method

A third harmonic distortion corrector is equipped for correcting a third harmonic distortion contained in a two-phase sinusoidal signals with different phases output from an encoder. A third harmonic calculator/detector calculates the amplitude aand the phase &#x3c6;of the third harmonic using Fourier analysis, based on change in radius r of the Lissajous waveform output from a r-&#x3b8; converter. The third harmonic distortion corrector corrects the third harmonic distortion of the two-phase sinusoidal signal ABbased on the amplitude aand the phase &#x3c6;of the third harmonic calculated.

In an electronic caliper, a detecting circuit detects displacement of a grid with respect to a scale, on the basis of a signal from a transducer A CPU displays the detected position on a display device . The CPU performs error detection on the transducer, only when the relative speed of the grid with respect the scale is zero, or becomes equal to or smaller than a predetermined value. Since error detection is performed only at a predetermined timing, power consumption can be reduced.

Position measuring device and error detecting method for the same, and electromagnetic induction position detecting device

An optical encoder is constructed by a reflection-type scale and a sensor head . The sensor head has an irradiation light source and a sensor board , the sensor board has a transparent substrate on which light-receiving areas for outputting displacement signals which have different phase with each other, and index gratings for modulating the scale irradiating light are formed to be alternately arranged. The index gratings are formed of the same material film as metal electrode of the light-receiving areas

Optical encoder and method of fabricating its sensor head

An encoder unit is disposed facing a scale. The encoder unit is constructed such that a processing circuit and a read head are integrally formed on one and the same semiconductor substrate. This construction results in size reduction and integral formation of the encoder unit.

Relative-displacement detecting unit and relative-displacement detecting device

A scale and a detecting head each include input/output connectors. Either of the input/output connectors is connected to receiving-side connector. By connecting the receiving-side connector to either of the scale and the detecting head, which is fixed in use, there is no change that a receiving-side cable will be disconnected by movement of the counterpart of the fixed member. This results in improvement of the reliability. Additionally, device is operable at high speed since the cable does not restrict motion of the movable member.

Displacement detecting device power supply and data communication device

An induction type tranducer is formed to be a substrate having a multilayer structure. The substrate has a multilayer structure including six layers, a first layer through sixth layer. An exciting coil is formed at the first layer. Detecting coils are formed at the second layer and the third layer. A wiring layer is formed at the fifth layer at the opposite side of the scale from the core layer. A signal processing IC is formed at the sixth layer. A magnetic shield layer, which insulates magnetic flux from the exciting coil, is formed at the fourth layer between the exciting coil and the signal processing IC.

Induction type transducer and electronic caliper

Output of an encoder are sampled by A/D converters 11a and 11b to be converted to N bits A-phase and B-phase digital data DA and DB. In a look-up table memory 12, reference phase angle data of phase divisions and average gradient vectors of changes in phase angle data within the phase divisions are stored, the phase divisions being addressed by the high order NU bits of data DA and DB. An arithmetic circuit 13 determines a vector inner product of an average gradient vector and phase-interpolating data represented by the low order NL bits of the data DA and DB to add the resultant to a phase angle data, thereby outputting an interpolated phase angle data.

Interpolation circuit for encoder having a look-up table memory with

A magnetic encoder that allows the power consumption to be reduced has a first member 1 magnetized at pitches .lambda. and a second member 2 disposed so as to be relatively movable to the first member 1. The second member 2 has at least four MR devices Ma1, Mb1, Ma2, and Mb2 with phases that differ from by .lambda./4 each. The MR devices Ma1, Mb1, Ma2, and Mb2 are connected as a bridge circuit. Thus, a displacement detecting circuit 30 that outputs two-phase sine wave signals INA and INB is structured. The detecting circuit 30 is intermittently activated by analog switches Sa1, Sb1, Sa2, and Sb2 driven by a first clock CK1. The output signals INA and INB of the detecting circuit 30 are sampled by sample hold circuits 41a and 41b, respectively. The sampled values are compared by comparators 42a and 42b, whereby binary data is obtained. The comparators 42a and 42b each have a bias circuit 44 that is intermittently driven by a second clock CK2.

Magnetic encoder using a displacement detecting circuit thereof

An interpolation circuit of an encoder of which dynamic accuracy is improved is disclosed. The phase angle data detecting circuit 1 detects to store the phase angle data PH for each of the first clock CK1. The phase angle data PH is input to the updating circuit 2 in which the current data CNT is subtracted from the subsequent phase angle data PH so as to be updated. The differential data DX is limited within an upper limit to be added to the current data CNT. The integrating circuit 3 integrates the differential data DELTA1, whose upper limit is predetermined, by the second clock CK2 to generate the carry signal QUADEN at each timing when the integrated value leads to the period ratio of CK1 to CK2. The two-phase square wave generating circuit 5 generates two-phase square wave signals at each timing of the carry signal QUADEN. The over-speed detecting circuit 6 monitors the differential data DX to generate the over-speed alarm signal OSALM under a predetermined condition.

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Kawasaki, Japan

Tetsuro Kiriyama