An angle sensor is provided for determining an absolute angle signal of a first part rotated with respect to a second part. The angle sensor comprises a first grating ring for generating a first signal representative of a relative position of a first sensor along a corresponding ring segment of the first grating ring. The angle sensor further comprises a second grating ring for generating a second signal representative of a relative position of a second sensor along the corresponding ring segment of the second grating ring. The first plurality and the second plurality are co-prime numbers and a difference between the first plurality and the second plurality being larger than 1. The angle sensor also comprises a calculator configured for calculating the absolute angle signal using a first linear combination of the first signal and the second signal.

An encoder apparatus comprising a scale comprising scale features in at least one track which define a series of incremental scale marks and at least one reference mark and a readhead comprising a light source, a diffraction grating, an incremental photodetector and a reference photodetector comprising at least two detector channels. The features defining the at least one reference mark are configured such that the at least one reference mark as resolvable by each of the at least two detector channels comprises a single feature. The optical arrangement of the encoder is such that a non-imaged representation of at least the track in which the at least one reference mark is contained falls onto the detector.

A vehicle wheel hub assembly includes an outer member configured to be mounted to a non-rotatable portion of the vehicle and an inner member rotatably supported in the outer member by a bearing and configured to support a vehicle wheel. A first target member is coupled with the inner member, and a first sensor is fixed to the outer member and positioned to sense an angular displacement of the first target member relative to the outer member and to produce a first output signal. A second target member is coupled with the inner member and is spaced axially from the first target member, and a second sensor is fixed to the outer member and positioned to sense an angular displacement of the second target member relative to the outer member and to produce a second output signal.

A vehicle wheel hub assembly includes an outer member configured to be mounted to a non-rotatable portion of the vehicle and an inner member rotatably supported in the outer member by a bearing and configured to support a vehicle wheel. A first target member is coupled with the inner member, and a first sensor is fixed to the outer member and positioned to sense an angular displacement of the first target member relative to the outer member and to produce a first output signal. A second target member is coupled with the inner member and is spaced axially from the first target member, and a second sensor is fixed to the outer member and positioned to sense an angular displacement of the second target member relative to the outer member and to produce a second output signal.

An encoder scale includes a tabular base material and an optical pattern provided above one surface of the base material, a first region and a second region being disposed side by side above the optical pattern. The first region includes a resin layer disposed above the base material and including photosensitive resin and a metal film disposed above the resin layer and formed of a metal material. The surface of the first region is configured mainly by a first surface having a normal line in the thickness direction of the base material. The surface of the second region is configured mainly by a second surface inclined with respect to the first surface.

The present invention is the optical fiber sensor, that laser pulses from a laser source are separated into a reference path and a measurement path by the second optical coupler via the first optical coupler, the first FRM is provided at an end of the reference path, the second FRM is provided at an end of the measurement path, and the reference reflected light of the first FRM and the measurement reflected light of the second FRM are interfered at the second optical coupler and are converted into three phases. The first phase pulses are transmitted to the optical synthesis section via the first optical coupler, second phase pulses are transmitted to the optical synthesis section via the first delay section, and third phase pulses are transmitted to the optical synthesis section via the second delay section. The time division pulse train is outputted from the optical synthesis section.

A device for detecting posture change of a operation part in a camera and a method for restoring posture are disclosed. The device may include a photo interrupter and a photoelectric baffle structure including a plurality of baffle pieces fixed on a base. The baffle pieces may include a first baffle piece and remaining second baffle pieces of a length specification different from that of the first baffle piece, and there is a gap between two adjacent baffle pieces. An output signal from the photo interrupter changes according to the aligning relationship between the photo interrupter and the baffle pieces. One of the photoelectric baffle structure and the photo interrupter may follow the motion of an operation part of the camera while the other one remains unmoved, so that a posture change of the operation part may be detected based on the output signal from the photo interrupter.

An encoder according to an embodiment of this disclosure includes a voltage generation circuit connected to a power supply through a diode and having a variable resistor, the voltage generation circuit outputting a voltage corresponding to a current flowing through the diode and a resistance value of the variable resistor, as a threshold value; a comparator for performing a comparison between an analog signal inputted from a detector for detecting rotation of a motor and the threshold value inputted from the voltage generation circuit, and outputting a comparison result as a comparator output; a resistance value variation circuit for varying the resistance value of the variable resistor; and a threshold value determination circuit for determining the threshold value based on a relationship between the resistance value and the comparator output.

A rotary encoder for detecting the angle of rotation of a first rotatable shaft, with a first mark which is coupled with the first shaft, a second mark which is coupled with the second rotatable shaft, a third mark which is coupled with the second shaft, a fixed fourth mark and means for detecting a passage of the third mark though a vicinity of the fourth mark and means for detecting a coincidence of the angles of rotation of the first and the second marks.

An optical element for generating diffraction orders for an encoder apparatus, in which the optical element includes an array of diffraction features arranged such that the spacing between the centres of adjacent diffraction features varies irregularly from one pair of adjacent features to the next.