Abstract: A position detection error correcting method that corrects position detection errors using a limited storage capacity, by calculating position detection error correction values by four simple arithmetic operations at startup to reduce a startup time delay and consumption of a storage capacity even when a portion containing steep error variations exists. Detection error correction values of a position detector are expressed by a correction function using a periodic function, and correction parameters of the correction values are stored in advance in a non-volatile memory. At startup, these correction parameters are read out, and a position detection error correction value corresponding to each detected position is calculated and stored in a random access memory. The output position detection error correction value detector corresponding to each detected position is read out from the random access memory and a corrected detected position value corrected for the detected position value error is calculated.

Abstract: A position detection error correcting method that corrects position detection errors using a limited storage capacity, by calculating position detection error correction values by four simple arithmetic operations at startup to reduce a startup time delay and consumption of a storage capacity even when a portion containing steep error variations exists. Detection error correction values of a position detector are expressed by a correction function using a periodic function, and correction parameters of the correction values are stored in advance in a non-volatile memory. At startup, these correction parameters are read out, and a position detection error correction value corresponding to each detected position is calculated and stored in a random access memory. The output position detection error correction value detector corresponding to each detected position is read out from the random access memory and a corrected detected position value corrected for the detected position value error is calculated.

Abstract: A rotary type encoder is provided with a signal generating portion 2 for generating a sine wave signal of N periods for each revolution in accordance with the rotation of the shaft 4 of a motor; a calculation means for obtaining the rotation angle of the shaft 4 based on the sine wave signal; an EEPROM 37 being arranged in a manner that the error value of the rotation angle for one revolution of the shaft 4 thus measured is divided in relation with the N periods to set a plurality of first angle regions i, the angle region almost at the center of the angle region i is divided into plural regions to set second angle regions j, and an error value corresponding to the angle at almost the center of each of the angle regions j is stored therein in correspondence with the rotation angle; and a correction means for reading the error value stored in the EEPROM 37 in correspondence with the rotation angle to correct the rotation angle.

Abstract: A rotary type encoder is provided with a signal generating portion 2 for generating a sine wave signal of N periods for each revolution in accordance with the rotation of the shaft 4 of a motor; a calculation means for obtaining the rotation angle of the shaft 4 based on the sine wave signal; an EEPROM 37 being arranged in a manner that the error value of the rotation angle for one revolution of the shaft 4 thus measured is divided in relation with the N periods to set a plurality of first angle regions i, the angle region almost at the center of the angle region i is divided into plural regions to set second angle regions j, and an error value corresponding to the angle at almost the center of each of the angle regions j is stored therein in correspondence with the rotation angle; and a correction means for reading the error value stored in the EEPROM 37 in correspondence with the rotation angle to correct the rotation angle.

Abstract: A photoelectric rotary encoder includes a light source that emits a light beam, a returning section that returns the emitted light beam to a direction opposite to an emitting direction of the beam, and a photodetector that is disposed on a substrate on which the light source is disposed and that detects the returned light beam via a disk having a detection pattern section. The photoelectric rotary encoder detects rotational displacement of the disk based on the detected returned light beam. In this photoelectric rotary encoder, an optical element that lets a stray beam component of the light beam from the light source escape via a side surface of the optical element, is disposed in front of the substrate on which the light source and the photodetector are disposed. The optical element covers the substrate and integrates the optical element and the substrate.

Abstract: A scale generates a periodic light-intensity distribution pattern having a pitch upon irradiation by emission light from a light source. Light-detecting element groups are shifted relative to the scale to generate phase signals having fixed phase differences. Light-detecting elements are adjacently positioned to have the same phase to form each light-detecting element group. Area centers of gravity on a phase axis of the light-detecting element groups having a fixed phase difference are made coincident with each other.

Abstract: A scale (104) generates a periodical light-intensity distribution pattern having a predetermined pitch (P) with irradiation of emission light from a light source (102). A plurality of light-receiving element groups are shifted relative to the scale to generate phase signals having predetermined phase differences. A plurality of light receiving elements are adjacently positioned to have the same phase to form each light-receiving element group. Area centers of gravity (28,29; 38,39) on a phase axis (109) of a plurality of the light-receiving element groups having a predetermined relationship in phase difference are made coincident with each other.

Abstract: A photoelectric rotary encoder includes a light source that emits a beam, a returning section that returns the emitted beam to a direction opposite to a emitting direction of the beam, and a photodetector that is disposed on a substrate on which the light source is disposed and that receives the returned beam via a disk having a detection pattern section. The photoelectric rotary encoder detects a rotation displacement of the disk based on the received signal. In this photoelectric rotary encoder, an optical element that lets a stray beam component of the beam from the light source escape to the outside via the side surface of the optical element, is disposed in front of the substrate on which the light source and the photodetector are disposed. The optical element covers the substrate to integrate the optical element and the substrate together.

Abstract: An interference-type distance measuring device generates a reference beam having a first frequency and detection beam having a second frequency and directs these beams toward a moving detection unit which reflects these beams toward an interference system, where these beams are used to generate a detection interference wave. A reference interference wave generated by the interference system is converted into a first sine-wave signal, the interference detection wave is converted into a second sine-wave signal, first and second cosine-wave signals are generated from the first and second sine-wave signals, and the position of the motion detection unit is detected based upon these four signals.

Abstract: A position detection apparatus which can control an apparatus to be controlled, such as a motor or the like, more precisely, is disclosed. When a predetermined time has passed since reception of a request signal for requesting output of the position data was detected, the position detector measures the output of a sensor for detecting the position of an object to be measured, and calculates the position data representing the position of the object at a point of time when the measurement was performed, based on the measured output.

Abstract: An absolute-value encoder device for detecting a plurality of rotation quantities is disclosed. An A/B phase forming portion 610 forms an A-phase pulse signal and a B-phase pulse signal, based on light passing through a slit rotating together with a rotary shaft. One period of each of those pulse signals corresponds to one revolution of a rotary shaft. The A- and B-phase pulse signals are displaced in phase by 90° from each other. When an A/B-phase state detecting portion 640 detects a state change of each of those pulse signals, a clock forming portion 66 changes a frequency of a clock pulse signal to another frequency.

Abstract: A position detection apparatus which can control an apparatus to be controlled, such as a motor or the like, more precisely, is disclosed. When a predetermined time has passed since reception of a request signal for requesting output of the position data was detected, the position detector measures the output of a sensor for detecting the position of an object to be measured, and calculates the position data representing the position of the object at a point of time when the measurement was performed, based on the measured output.

Abstract: In a position detecting apparatus which detects an absolute position by A/D converting sinusoidal and cosinusoidal signals and performing interpolation, a phase error between the signals which is caused by movement of a detection object during the A/D conversion is corrected, thereby enabling sample hold circuits which have been necessary for maintaining the synchronism of analog signals to be omitted, so as to realize the cost reduction and miniaturization. This is enabled also in an apparatus of high resolution. Position data at requests of the last and preceding times are stored into a RAM 12. On the basis of the position data, a CPU 10 predicts the amount of a phase shift of another signal due to movement during A/D conversion of one signal, corrects the predicted phase shift amount, and then calculates the position data.

Abstract: The encoder provided by the present invention computes an obtains a difference value between a maximum value and a minimum value of a simulated sinusoidal signal from the signal detecting section, computes an amplitude of said simulated sinusoidal signal in the amplitude computing section according to the difference value, decides an optimal reference voltage for an A/D converter or an optimal amplification factor and an optimal reference voltage for a signal amplifier for simulated sinusoidal signals, and sets a reference voltage for the A/D converter or an amplification factor and a reference voltage for the signal amplifier according to the optimal values.

Abstract: An absolute position detection apparatus which comprises sine and cosine wave generators for generating one or more sets of sine and cosine waves within a cycle, analog-to-digital converters for converting the incoming sine and cosine waves generated by the sine and cosine wave generators into digital values. An arithmetic unit is used for calculating a compensation for errors including offset, amplitude and phase errors on the basis of the digital values from the analog-to-digital converters. In the apparatus, the arithmetic unit operates on a phase angle from phase angles found by the arithmetic performed prior to or during said error compensations and the digital values from the analog-to-digital converters, whereby a low-priced, highly reliable absolute position detection apparatus can be achieved without the addition of compensation circuits to the hardware.

Abstract: The position of a machine tool or the like is accurately obtained by an absolute value encoder. Light emission elements emit light which passes through scales containing optical patterns and is detected by light receiving elements. First, a signal detected by the light receiving elements while the light emission elements are extinguished is stored in memory. Then, the light emission elements are lighted and the signal detected by the light receiving elements is corrected by the previously stored signal.