Abstract: A resistor string outputs sixteen signals with a phase difference of 22.5° by dividing voltage between two adjacent phases of a four-phase input signal with a phase difference of 2?/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° 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.

Abstract: A resistor string outputs sixteen signals with a phase difference of 22.5° by dividing voltage between two adjacent phases of a four-phase input signal with a phase difference of 2?/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° 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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 a3 and the phase ?3 of the third harmonic using Fourier analysis, based on change in radius r of the Lissajous waveform output from a r-? converter. The third harmonic distortion corrector corrects the third harmonic distortion of the two-phase sinusoidal signal A4, B4 based on the amplitude a3 and the phase ?3 of the third harmonic calculated.

Abstract: 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.

Abstract: 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 a3 and the phase ?3 of the third harmonic using Fourier analysis, based on change in radius r of the Lissajous waveform output from a r-? converter. The third harmonic distortion corrector corrects the third harmonic distortion of the two-phase sinusoidal signal A4, B4 based on the amplitude a3 and the phase ?3 of the third harmonic calculated.

Abstract: 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.

Abstract: In an electronic caliper, a detecting circuit 112 detects displacement of a grid with respect to a scale, on the basis of a signal from a transducer 110. A CPU 114 displays the detected position on a display device 124. The CPU 114 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.

Abstract: An optical encoder is constructed by a reflection-type scale 1 and a sensor head 4. The sensor head 4 has an irradiation light source 2 and a sensor board 3, the sensor board 3 has a transparent substrate 30 on which light-receiving areas 5 for outputting displacement signals which have different phase with each other, and index gratings 6 for modulating the scale irradiating light are formed to be alternately arranged. The index gratings 6 are formed of the same material film as metal electrode of the light-receiving areas 5.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: In an electronic caliper, a detecting circuit 112 detects displacement of a grid with respect to a scale, on the basis of a signal from a transducer 110. A CPU 114 displays the detected position on a display device 124. The CPU 114 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.

Abstract: A scale 10 and a detecting head 20 include input/output connectors 94 and 96, respectively. Either of the input/output connectors is connected to a receiving-side connector 98. By connecting the receiving-side connector 98 to either of the scale 10 and the detecting head 20, which is fixed in use, there is no chance that a receiving-side cable 99 is disconnected by the movement of the counterpart of the fixed member. This results in improvement of the reliability. Additionally, the device is operable at high speed since the movable member is not restricted in its motion by the cable 99.

Abstract: An encoder unit 10 is disposed facing a scale 12. The encoder unit 10 is constructed such that a processing circuit 14 and a read head 16 are integrally formed on one and the same semiconductor substrate. This accrues to size reduction and integral formation of the encoder unit.