An optical encoder includes a scale, a calculator, and a head having a light source, an image capturer, and a lens array having first and second lenses. The calculator includes a signal generator, an extractor, a signal combiner, and a displacement calculator. The signal generator generates a sine wave signal. The extractor extracts first and second regions. The signal combiner, based on an inter-regional distance, uses a sine wave signal of the second region to generate a sine wave signal that extends to a first end of the first region such that the generated sine wave signal overlaps with a sine wave signal of the first region. The signal combiner also combines the sine wave signal of the first region with the generated sine wave signal. The displacement calculator calculates an amount of relative displacement based on the sine wave signal that is combined by the signal combiner.

There is provided a motor driving system in which an encoder sensor is configured to move with a driven object with respect to an encoder scale and output an encoder signal. A controller is configured to control a motor based on the encoder signal, thereby controlling movement of the driven object. The controller estimates an obstructing area. In the obstructing area, the encoder sensor reads a part of the encoder scale where an obstacle is adhered. The controller calculates a control error of the motor in the obstructing area based on the encoder signal output after the encoder sensor passes through the obstructing area, and determines a compensation amount of a controlling input value input during a period while the encoder sensor passes through the obstructing area.

A method includes imaging, with an optical read head attached to a second mechanical component, a portion of an encoder track disposed on a first mechanical component. The encoder track has a first encoder scale extending along the encoder track and a second encoder scale extending along the encoder track, and the imaged portion of the encoder track includes a first portion of the first encoder scale and a second portion of the second encoder scale. The method further includes transforming an imaged portion of the encoder track to a spatial frequency domain; identifying a pair of frequency bins in the spatial frequency domain; determining a phase difference between a first frequency bin and a second frequency bin in the pair of frequency bins; and mapping the phase difference to a positional relationship between the first mechanical component and the second mechanical component.

There is provided an optical encoder with alignable relative positions between elements including an encoding medium, a sensor package and a memory. The sensor package includes a photodiode array and two alignment photodiodes opposite to the encoding medium. The memory records an alignment pattern associated with output signals of the two alignment photodiodes when the encoding medium and the sensor package are at nominal operating positions. When the encoding medium and the sensor package are not at the nominal operating positions, the relative position alignment is performed by adjusting current relative positions between the encoding medium and the sensor package to cause a current pattern associated with output signals of the two alignment photodiodes to be identical to the alignment pattern.

In order to provide an optical encoder with high resolution, the optical encoder includes: a rotary scale provided with a grating pattern having a first radial pattern and a plurality of concentric circular patterns disposed at predetermined intervals; and a light receiving element which detects a first interference fringe formed by the first pattern having a first period in the circumferential direction, a second interference fringe which is diffracted in a direction of the first interference fringe by a grating pattern having a second period in the circumferential direction disposed at a different radial position so that the second interference fringe has a period closer to the first period than the second period.

There is provided an operating method of an optical positioning system including: capturing an image frame of a detected surface, which has interleaved bright regions and dark regions, using a field of view and a shutter time of an optical sensor; counting a number of edge pairs between the bright regions and the dark regions that the field of view passes; calculating an average value of the image frame; calculating a ratio between the calculated average value and the shutter time; determining that the field of view is aligned with one of the dark regions when the ratio is smaller than a ratio threshold; and determining that the field of view is aligned with one of the bright regions when the ratio is larger than the ratio threshold.

An optical encoder includes a first grating pattern having a first pitch, a second grating pattern having a second pitch, a third grating pattern having a third pitch different from the second pitch, and a light receiving element configured to receive light from the third grating pattern in an order from a side of a light source, wherein first moire fringes including a shadow of the third grating pattern are formed on an exit plane of the third grating pattern due to a difference between the second pitch and the third pitch, and wherein the light receiving element receives light that forms second moire fringes in which the shadow of the third grating pattern is smoothed more than in the first moire fringes by placing the third grating pattern and the light receiving element away from each other.

An encoder apparatus includes an encoder and a processor. The encoder includes a scale portion, a light emitting portion, and a light receiving portion. The scale portion includes a first track and a second track. The processor obtains a plurality of candidate values of a gap between the light emitting portion and the scale portion on a basis of an amplitude of a first signal obtained by receiving light reflected on or transmitted through the first track by the light receiving portion. The processor determines a measured value from among the plurality of candidate values on a basis of an amplitude of a second signal obtained by receiving light reflected on or transmitted through the second track by the light receiving portion.

There is provided an optical encoder including a photodiode array and a code disk opposite to each other. The photodiode array includes at least three sets of position photodiodes and two index photodiodes arranged transversally. The two index photodiodes are adjacently arranged at the same side of the at least three sets of position photodiodes. A first set of position photodiodes and a last set of position photodiodes of the at least three sets of position photodiodes are partially covered to alleviate the total harmonic distortion. The rest position photodiodes of the at least three sets of position photodiodes other than the first and last sets of position photodiodes are not covered.

The invention relates to a reflective coating (12) for means for reflecting a light beam emitted by a light source of an optical encoder, the reflection of the light beam being directed toward a photoreceptor. The coating (12) comprises at least one flat lamella made of glass, one face of which forms a connection means on one portion of the reflection means of the optical encoder, the lamella being provided, on the face opposite the face forming the connection means, with at least one layer made of at least one material having a reflection coefficient greater than 96% coated with a protective layer.