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.