Abstract: An interferometric fiber optic encoder readhead for sensing the displacement of a scale grating is disclosed. The detector channels of the readhead are fiber optic detector channels having respective phase grating masks. The fiber optic encoder readhead is configured to detect the displacement of interference fringes arising from the scale grating. In various exemplary embodiments, the fiber optic readhead is constructed and operably positioned according to various design relationships that insure a compact mounting and a relatively ideal sinusoidal signal as a function of displacement. Accordingly, high levels of displacement signal interpolation may be achieved, allowing sub-micrometer displacement measurements. The fiber optic encoder readhead may be assembled in a particularly accurate and economical manner and may be provided in a package with dimensions on the order of 1–2 millimeters.

Abstract: An optical position measuring system including a scale and a scanning unit. The scanning unit includes a light source that emits light beams and a periodic scanning graduation having scanning graduation marks arranged periodically at a scanning graduation period along a measuring direction. The scanning unit further including a detector arrangement. The scanning graduation or the scale graduation includes at least three partial tracks, which adjoin perpendicularly with respect to the measuring direction, and graduation marks associated with each of the at least three partial tracks have a defined and constant offset spacing from their nominal positions, wherein the offset spacings associated with adjoining ones of the at least three partial tracks differ, so that filtering of undesired harmonic waves out of the at least one periodic scanning signal results from said offset spacings.

Abstract: A rotary optical encoder is described to provide the pole position of the rotor in a permanently magnetized motor. Using a simple opening design of code tracks and two light sensors along with a corresponding processing circuit, only one additional code track is required on the code wheel to output phase-changing signals. Thus the rotary optical encoder with phase-changing signal with low cost and small size is implemented.

Abstract: A photoelectric encoder includes an optical receipt chip on which a plurality of photodiodes (PDs) are laid out along a measurement axis “X” so that these are organized into an array. The layout pitch of PDs disposed at end portions of the array is made less than the pitch of those at a central portion of the array. Similarly the width of a light acceptance surface of the former is less than that of the latter.

Abstract: An optical phased array transmitter/receiver includes a plurality of waveguides each including an optical fiber and a light source coupled to the fibers in the waveguides. At least one grating is coupled to the fiber of each waveguide and at least one phase shifter coupled to the fiber of at least one waveguide. The phase shifter controls a phase profile of light passing through the fiber to control a profile of a laser beam reflected at the grating. The gratings reflect light passing through the fibers outside of the optical coder to form a laser beam shaped and directed by the grating and phase shifters. Further, a detector is coupled to the waveguides that is enabled to receive light reflected off the gratings. Other embodiments are described and claimed.

Abstract: A 2D fiber optic encoder readhead having multiple readhead portions for sensing the two-dimensional displacement of a scale grating is disclosed. The detector channels of the readhead portions are fiber optic detector channels having respective phase grating masks. At least two of the phase grating masks have different orientations so as to facilitate the detection of displacement in at least two different directions. The 2D fiber optic encoder readhead portions are configured to detect the displacement of a self-image pattern that results from a corresponding pattern on the scale grating. The self-image pattern allows for the detection of displacement in the at least two different directions. In various exemplary embodiments, the fiber optic readhead portions are constructed according to various design relationships that insure a robust signal-to-noise ratio. Accordingly, high levels of displacement signal interpolation may be achieved.

Abstract: A position-measuring device includes a measuring graduation extending along a measuring direction, a scanning unit for scanning the measuring graduation, and a detection device of the scanning unit including a plurality of detector elements that are arranged periodically one after the other along an extension direction and that, during scanning of the measuring graduation, generate output signals able to be supplied to an evaluation unit. In each case, a plurality of adjacent detector elements are interconnected to form a detector group such that their output signals are able to be joined and supplied as a unified signal to the evaluation unit. The detector elements are combined to form detector groups, and are arranged in the form of detector groups one after the other along the extension direction such that at least one defined harmonic is eliminated from the output signals.

Abstract: A position control method by motor drive including of rotating a rotor of the motor drive according to the given target opening, and detecting the opening of a movable vane by an encoder, the motor drive opening and shutting a passage of an intake air pipe to a turbo charger of the automobile by the movable vane, and controlling the movable vane in the passage of the intake air pipe so that it reaches the target opening. The rotational position of the motor drive is controlled to the stop position in the direction where the movable vane is closed and the stop position in the direction where the movable vane is opened. The motor drive is controlled so that the passage of the intake air pipe becomes the target opening by setting the stop position as an operation reference position of the motor drive, and setting between the stop positions as the driving dynamic range motor drive.

Abstract: Three rotation sensors circumferentially arranged at 90 degree intervals in a disk code wheel attached to a motor's output shaft respectively output a signal corresponding the rotational speed of the wheel. An error component of one period (one-periodic component) or an error component of two period (two-periodic component) is generated per rotation when the code wheel is eccentric to the output shaft or is elliptically deformed, respectively. Control means averages the signals of the first and second sensors to obtain a first correction signal and subtracts the signal of the third sensor from the signal of the first sensor to obtain a second correction signal while removing the two-periodic component. The control means subtracts or adds the first correction signal relative to the second correction signal upon coinciding these signals in phase and amplitude to calculate a rotation measurement signal from which the periodic components are removed.

Abstract: An optical position sensing device for sensing a two-dimensional displacement, comprising a first photosensor arranged parallel to a first axis; a second photosensor arranged parallel to a second axis, wherein the first and the second axis are at an angle with respect to each other; and an encoding means which interferes with a path of light incident on the photosensors such that a pattern consisting of light and shadow is cast onto the photosensors, wherein the encoding means and the photosensors are able to move with respect to each other, resulting in modulation of light received by the photosensors, and are arranged in an arrangement such that when the encoding means moves relatively in a direction parallel to the first axis, the modulation of light received by the second photosensor is larger than the modulation of light received by the first photosensor; and when the encoding means moves relatively in a direction parallel to the second axis, the modulation of light received by the first photosensor is l

Abstract: An absolute position fiber optic encoder readhead having multiple readhead portions for sensing the displacement of respective scale grating tracks of a scale is disclosed. The detector channels of the readhead portions are fiber optic detector channels having respective phase grating masks. The fiber optic encoder readhead portions are configured to detect the displacement of a self-image of a respective scale grating track of the scale. In various exemplary embodiments, the fiber optic readhead portions are constructed according to various design relationships that provide a relatively high signal-to-noise ratio. Accordingly, high levels of displacement signal interpolation may be achieved, allowing submicrometer displacement measurements.

Abstract: A projection linear encoder has an SOQ substrate formed with transmission gratings and grid-like photodiode groups, and a reflecting grating plate with reflecting gratings that are formed facing thereto. A light-blocking film composed of a metal thin film or the like is formed on a surface of a glass substrate of the SOQ substrate, and the transmission gratings are formed by patterning the light-blocking film. The photodiodes are integrally formed by epitaxial growth on the silicon layer of the SOQ substrate. Transmission gratings with high mechanical strength can be formed inexpensively in comparison with cases in which through holes are formed by etching a silicon substrate to manufacture transmission gratings.

Abstract: Systems and methods are disclosed for providing position measurement information. For example, in accordance with one embodiment of the present invention, a multiple-pitch grating is employed to receive one or more laser beams and provide an output laser beam encoded with position information of the grating.

Abstract: A position encoder uses a track encoded with a pattern of bit-widths in accordance with a sequence. The sequence may be any sequence having unique subsequences, and may be a pseudo-random noise (PRN) sequence such that each N-bit subsequence occurs only once on the track. Sensors detect transitions between the bits and bit-widths as the track moves with respect to the sensors to provide in-phase and quadrature-phase pick-off signals. The pickoff signals are summed and absolute value thresholded. The absolute value thresholded sum signal is sampled when the quadrature pairs are in the “00” or “11” quadrants, and latched when the sum signal goes high to distinguish between wide and narrow bit widths. The latch is shifted into a shift data register for use in determining the position of the encoder track. In the case of a PRN sequence having a length of 2N bits, the position may be an absolute position when the number of valid bits in the shift data register is at least N.

Abstract: A displacement pickup is provided which includes a displaceable scale (12) having defined therein a first area (12a) where positional information is recorded with a predetermined pitch and a second area (12b) where positional information is recorded with a predetermined pitch different from that in the first area (12a), a first reading system (10) to read the positional information recorded in the first area (12a), a first phase detector (14) to detect a first phase on the basis of the positional information read by the first reading system (10), a second reading system (11) to read the positional information recorded in the second area (12b), a second phase detector (15) to detect a second phase on the basis of the positional information read by the second reading system (11), a phase comparator (16) to make a comparison between the first and second phases, and an origin signal generator (17) to generate an origin signal according to the result of comparison from the phase comparator (16).

Abstract: An optical encoder includes a scale having an optical grating formed thereon, a plurality of light-receiving devices, a light-emitting device, and a position-information detecting unit. The plurality of light-receiving devices is movable with respect to the scale. The light-emitting device applies light to the plurality of light-receiving devices through the scale. A position-information detecting unit detects position information in one cycle of a two-phase signal supplied from the light-receiving device. A determining unit determines an amplitude of an analog signal based on the position information.

Abstract: The invention is a system and method for automatically determining a resolution of an encoder, automatically calibrating the encoder resolution, and automatically determining a length of a workpiece from the encoder resolution and encoder count. The system comprises an encoder for generating an encoder signal indicative of linear movement of a moving workpiece traveling along a path. The system also comprises a first sensor positioned along the path traveled by the workpiece, the first sensor generating a first sensor signal in response to sensing an identifying characteristic of the workpiece. The system further comprises a second sensor positioned along the path traveled by the workpiece, the second sensor generating a second sensor signal in response to sensing the identifying characteristic of the workpiece, said second sensor being positioned a known distance from the first sensor along the path traveled by the workpiece.

Abstract: A scanning unit for an optical position measuring device for scanning a periodic strip pattern in a detector plane, the scanning unit including a detector arrangement including a first detector array with a first set of several radiation-sensitive detector elements, which are arranged next to each other in a first direction on a common support substrate and a second detector array including a second set of several radiation-sensitive detector elements arranged adjacent to the first detector array in a second direction perpendicular with respect to the first direction a detection plane. The second set of several radiation-sensitive detector elements are arranged next to each other in the first direction with a common period PDET, and have a geometrically defined offset (?x1i) in the first direction with respect to the first set of several radiation-sensitive detector elements.

Abstract: A displacement information detector in which a coherent luminous flux from a light source is applied to a diffraction grating scale adapted to be relatively moved to generate two diffracted rays of light having different orders, and the two diffracted rays of light are diffracted and deflected in a diffraction grating in which circular or toric curves are arranged in lattice at unequal pitches to be irradiated to the diffraction grating scale again to be rediffracted, and the diffracted rays of light are combined with each other to be made interfere each other, and the resultant interference light is introduced into a light receiving element to thereby detect a periodic signal due to the relative movement of the diffraction grating scale.

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 rotary encoder has a disc, a pair of photo-interrupters, an adjusting member, and a shifting controller. The disc rotates around a rotating axis and has slits that are formed circumferentially at given intervals. Each of the photo-interrupters has a light-emitting device and a photo-detecting device opposite one another, and generates two signals with a phase difference. Each photo-interrupter is pivotable around a pivot coaxial with the rotating axis, and is arranged along the circumferential direction of the disc so as to position the slits between the light-emitting device and the photo-detector. The adjusting member contacts the pair of photo-interrupters, and is movable along a shifting direction corresponding to a radial direction of the disc, so as to engage the pair of photo-interrupters. The adjusting member adjusts a relative position-relationship between the pair of photo-interrupters associated with the phase difference.

Abstract: A position measuring system that includes a scale having an incremental graduation track of a defined incremental graduation period and on at least one defined reference position, a reference marking field with a mean reference marking graduation period. A scanning unit movable with respect to the scale, the scanning unit having a plurality of scanning elements for generating scanning signals, wherein at least two phase-shifted incremental signals are generated as scanning signals. A first evaluation device that determines a rough reference position. A second evaluation device that determines a beat signal phase. A third evaluation device, which is suitable for unequivocally marking a beat signal period from the rough reference position and, if a defined phase position exists, to issue a fine reference position from the beat signal phase.

Abstract: A fiber optic encoder readhead for sensing the displacement of a scale grating is disclosed. The detector channels of the readhead are fiber optic detector channels having respective phase grating masks. The fiber optic encoder readhead is configured to detect the displacement of a self-image of the scale grating. In various exemplary embodiments, the fiber optic readhead is constructed according to various design relationships that insure a robust signal-to-noise ratio. Accordingly, high levels of displacement signal interpolation may be achieved, allowing sub-micrometer displacement measurements. The fiber optic encoder readhead may be assembled in a particularly accurate and economical manner and may be provided in a package with dimensions on the order of 1-2 millimeters.

Abstract: A photoelectric encoder includes an optical receipt chip on which the light acceptance surfaces of a plurality of photodiodes are disposed two-dimensionally. Four optical signals different in phase from one another (i.e., light signals with phase “A,” phase “B,” phase “AA,” and phase “BB”) are guided to fall onto the light acceptance surfaces. The shape of each light acceptance surface is a regular hexagon.

Abstract: A method and system for determining the position of a movable member in an electronic input device within a predefined resolution. Two offset signals indicate the position of the movable member. The time required for each signal to cross a threshold level is measured and inverted, revealing an offset sinusoidal relationship. The offset sinusoids may be plotted against each other to reveal an approximate circle of inverse time samples for a cycle. Corresponding inverted minimum and maximum times are used to determine a center reference value for each signal. As a function of the inverted times, a quadrant of the circle is determined. Within a quadrant, a sector most closely corresponding to the position of the movable member is determined from among a plurality of predefined sectors that define the resolution. A number of sectors between position samples of the movable member are accumulated and communicated to a host device.

Abstract: A rotational phase difference detecting system, a method that is capable of very accurately detecting a rotational phase difference between a plurality of rotating bodies, a machine operating-state monitoring system, and a method employing the rotational phase difference detecting system. The detecting system has a first rotating body with a first mark, a second rotating body with a second mark, a mark sensor for detecting the first mark, a first camera for imaging the second mark when the mark sensor detects the first mark, and a display section for displaying the second mark imaged by the first camera. The rotational phase difference is detected from a position of an image of the second mark displayed on the display section and is thus detected very accurately with a simple construction comprising the mark sensor, the first camera, and the display section.

Abstract: In detecting units for detecting the rotating operation of a ball, respective photoemitters serving as light sources are intermittently driven to emit light and respective photodetectors receive the light. A control unit recognizes a moving speed in the X-axial direction and that in the Y-axial direction from detection signals obtained by the detecting units. In the control operation of the control unit, when an increase in operating speed is detected, a light emitting period of each of the photoemitters is reduced. When a decrease in operating speed is detected, the light emitting period of each photoemitter is extended.

Abstract: An optical encoder includes a scale having an optical grating formed thereon, a plurality of light-receiving devices, a light-emitting device, and a position-information detecting unit. The plurality of light-receiving devices is movable with respect to the scale. The light-emitting device applies light to the plurality of light-receiving devices through the scale. A position-information detecting unit detects position information in one cycle of a two-phase signal supplied from the light-receiving device. A determining unit determines an amplitude of an analog signal based on the position information.

Abstract: An optical displacement measurement apparatus increasing the valid light receiving area struck by light so as to give a larger signal and reducing the effect of any unevenness or spottiness of the illuminance of the light source or any scratches or dirt on the glass scale is provided. The apparatus has a plurality of light receiving element arrays having a plurality of light receiving elements, has a plurality of light receiving element groups having a plurality of light receiving element arrays, has the plurality of light receiving element arrays arranged shifted by predetermined distances in the direction of movement of the glass scale, and has the light receiving element groups arranged shifted by predetermined distances with respect to the direction of movement of the glass scale.

Abstract: A position measuring system that includes a scale having an incremental graduation track of a defined incremental graduation period and on at least one defined reference position, a reference marking field with a mean reference marking graduation period. A scanning unit movable with respect to the scale, the scanning unit having a plurality of scanning elements for generating scanning signals, wherein at least two phase-shifted incremental signals are generated as scanning signals. A first evaluation device that determines a rough reference position. A second evaluation device that determines a beat signal phase. A third evaluation device, which is suitable for unequivocally marking a beat signal period from the rough reference position and, if a defined phase position exists, to issue a fine reference position from the beat signal phase.

Abstract: Systems and methods analyze the performance of a mechanical system having two identical rotating members therein. Light is directed from two identical light sources to intercept encoded portions of the rotating members. A portion of the light is reflected from the encoded portions of each rotating member. The reflected portion of the light can be then detected to recover performance data maintained therein, wherein the performance data contains performance characteristics of the mechanical system. A reflected portion of the light can be detected to recover performance data. The light sources can be configured as Vertical Cavity Surface Emitting Lasers (VCSEL). The encoded portions of rotating members thereof can include a bar code. Images from a first encoded surface may interact with an image from a second encoded surface after the light beams are reflected off the first and second rotating surfaces to produce Moirè fringes.

Abstract: A position measuring device for generating position-dependent output signals that includes a scanning element by which a scanning plane is defined and a measuring graduation movable relative to the scanning element and defining a measuring graduation plane. The position measuring device further includes a regulating device for regulating output signals to constant signal amplitudes, in that the regulating device acts upon a predetermined controlling variable, to which end the requisite value of the controlling variable for the purpose of regulating is ascertained continuously by the regulating device.

Abstract: An optical encoder has a light irradiating device; an optical scale having a grating for transmitting or reflecting incident light; light-receiving elements disposed in a plurality of different directions; and an optical system for amplitude-modulating light traveling from the light irradiating device to the optical scale and transmitted or reflected by the grating, by a dividing element in which a plurality of V-shaped grooves are juxtaposed, and for dividing the amplitude-modulated light into beams along a plurality of different directions to guide the beams to the respective light-receiving elements. The dividing element is comprised of repetitions of such structure that a plurality of V-grooves consisting of planes of mutually different angles are juxtaposed at a predetermined pitch.

Abstract: A P-ECU controls an actuator which drives a shift control mechanism. An encoder signal acquisition unit acquires signals output from an encoder which detects a rotational angle of the actuator. A counter calculates a count value from the output signals of the encoder. An energization control unit controls energization to the actuator. A first phase-matching unit uses the Z-phase signal of the encoder to match the count value with energized phases so as to find a correspondence therebetween and a second phase-matching unit matches the count value with energized phases to find a correspondence therebetween without using the Z-phase signal of the encoder. If the first phase-matching unit detects an abnormality of the encoder, the second phase-matching unit subsequently performs phase matching.

Abstract: An optical position measuring device that includes a measuring graduation and a scanning unit, which moves relative to the measuring graduation along a measuring direction. The scanning unit includes a light source, a transmitting graduation with a graduation period PAT, on which a periodic strip pattern with a strip pattern period PSM results in case of a relative movement between the scanning unit and the measuring graduation. A detector arrangement arranged at a distance DDET from the scanning graduation with a plurality of blocks of individual detector elements, wherein the plurality of blocks are arranged periodically with a detector period PDET in the measuring direction. The transmitting graduation is at the distance u from the measuring graduation, the scanning graduation is at a distance v from the measuring graduation, and the detector period PDET has been selected in accordance with the equation PDET=m*1*Pv, wherein m=(1+DDET/(u+v+DLQ)) and 1=1, 2, 3, . .

Abstract: A confocal imaging system is equipped with a retroreflector, which oscillates with a high frequency, for increasing the data rate during the recording of distance values. A mirror system having a small mass is provided that, by use of an electrostatic drive, makes extremely rapid focusing movements or height detections possible in the case of a small mass. The mirror system includes two separate micromechanically produced mirrors, which are set at 90° to one another and which synchronously oscillate in the direction of the optical axis of the confocal imaging system.

Abstract: In an optical encoder, a rotary disk plate has slits formed along a circumferential direction and rotates to intermittently pass light through the slits such that the passed light has a periodical intensity variation. A stationary mask plate has apertures spatially shifted from each other and splits the passed light into two light fluxes having different phases of the periodical intensity variation due to the spatial shift of the apertures. Two light receiving elements receive the two light fluxes respectively, and generate two electric signals having a same cycle corresponding to the periodical intensity variation of the light fluxes and different electric phases. A light guiding member is provided between the stationary mask plate and the light receiving elements to guide the light fluxes while expanding the spacing between the light fluxes such that the light receiving elements are spaced from each other at a distance greater than the spacing of the light fluxes.

Abstract: An optical encoder comprises a light source unit, a scale which has a periodic optical pattern and displaces relatively to the light source unit, and a light detector to detect a light beam emitted from a light source of the light source unit and traveled by way of the scale. The light source unit has a light beam exit opening through which a light beam is emitted toward the scale. Assuming that z1 is a distance between the light beam exit opening and the scale, z2 is a distance between the scale and the light detector, and p1 is a pitch of the periodic optical pattern of the scale, the width W of the light beam exit opening in the scale moving direction is determined depending on the values of z1, z2, and p1.

Abstract: A scale (10) is illuminated by a light source (18). After interaction with an index grating (12), fringes (F) are formed in a Talbot plane and analyzed by an analyzer grating (14). To decrease the sensitivity to changes in the ride height of the index grating above the scale, the light source is restricted to a small but finite size, and positioned so that it subtends a small angle Ø at the analyzer grating (or, if a collimating lens (24) is used, positioned so that it subtends a small angle Ø at the lens). The size of the light source should preferably be smaller than a predetermined value such that the extent of a geometric fringe visibility envelope exceeds the extent of a Talbot fringe visibility envelope.

Abstract: A position measuring operation system for determining positions of a first object and a second object, which can be moved in relation to the first object, including a position measuring system having a light source that is operated in a pulsed manner and an evaluation unit connected to the position measuring device and arranged downstream of the position measuring device.

Abstract: A slit structure of an encoder for preventing the position precision at high speed operation from deteriorating.

Abstract: A position measuring system for determining the relative position of a first object and a second object movable relative to one another that includes an incremental track, associated with a first object and having a periodic line structure that has individual lines and a scanning unit, associated with a second object movable relative to the first object, that scans said periodic line structure and that generates a corresponding incremental signal. A sensor system that generates absolute position information pertaining to the relative position of the first and second objects, wherein the width of the individual lines, as measured along a longitudinal direction of the incremental track, varies over at least a portion of the breadth of the incremental track, as measured in a direction transverse to the longitudinal direction, in such a way that a structure with absolute position information is superimposed on the periodic line structure.

Abstract: An optical track sensing device, and in particular to an optical sensor for detecting optical tracking information on a moving medium (or stationary medium and moving sensor). The sensing device relies on self-imaging, rather than optics, and obtains a very acceptable detected signal at other than the self imaging plane of the reflection off a moving medium. This provides more flexibility in the placement of the sensor, while still allowing the elimination of optical components by relying on self-imaging instead. In addition, by providing a pattern over the photodetector with a smaller period, higher frequency harmonics are detected, allowing more precise detection of the position of the medium. In one embodiment, the period of the detector pattern is selected to detect the higher harmonics of the grating on the moving medium.

Abstract: An optical encoder with a high utilization efficiency of light and easy to manufacture. The optical encoder comprises a conversion device formed in such a manner that lens elements are arranged periodically with a reference pitch IP for converting a beam L emitted from a light source into a plurality of shifting beams MF. The beam L is contracted to a half of the reference pitch IP by the conversion device and goes out as a parallel beam, to impinge on a light receiving section. On a board of the light receiving section there are arranged light receiving elements with a pitch of IP/2. When an object connected to the conversion device is rotated or translated, the position of each lens element changes synchronously and the shifting beam MF scans an arrangement of the light receiving elements. As a result, a ratio of a light amount reaching the light receiving element changes periodically. The resultant electrical signal is processed by a well-known processing circuit.

Abstract: The invention proposes a method for determining a rotation angle (&PHgr;) and/or an angular difference (&dgr;) in a divided shaft (3), which has a number of phase tracks (1a, 1b, 2a, and 2b) disposed on it, which are provided with codes. Via an evaluation unit, each group of tracks (1a, 1b, 2a, and 2b) supplies a phase signal (&agr;1, &agr;2), which is respectively ambiguous with regard to a rotation of the shaft (3). The at least two phase signals (&agr;1, &agr;2) are added up in a weighted fashion to produce a signal S from which the integer portion and the non-integer portion are calculated. The non-integer portion is proportional to the angular difference (&dgr;) between the two track groups. The torque (M) is determined through multiplication with the spring rate of an interposed torque rod. The unambiguous torque (&PHgr;) is determined from the integer portion of the signal (S) and a phase value (&agr;1) or (&agr;2) with the aid of a weighted addition.

Abstract: The present invention relates to a rotary encoder for detecting an angle, and more particularly to an absolute encoder which can read a pattern even when rotating at high speed. The present invention also relates to an encoder reading device that projects a pattern formed on an encoder onto a light receiving means using light emitted from a light source means so as to read a position of the encoder. The light source means is configured to emit a pulse that is synchronized with a shift pulse for moving an electric charge to a transfer gate of the light receiving means, and that is sufficiently shorter than a time interval (accumulation time) of the shift pulse.

Abstract: This invention relates to a displacement information detecting apparatus which has a light beam illuminating system for making a light beam enter a first area of the grating portion of a relatively displaceable scale member provided with a grating portion having a wavefront dividing function in the direction of grating arrangement, a reflecting member for reflecting the light beam having emerged from the first area into which the light beam has been made to enter by the light beam illuminating system to enter a second area which is in a direction substantially perpendicular to the grating arrangement relative to the first area, and a plurality of light receiving portions for receiving a plurality of light beams created by the wavefront dividing function in the second area into which the light beam has been made to enter by the reflecting member, a signal corresponding to the displacement relative to the scale member being provided by the light reception by each of the light receiving portions.

Abstract: The position of the inner surface of a hollow metal workpiece on a machine tool is detected by connecting an operating member of the machine, preferably a tool, to a first terminal of an electric power source; connecting the inner surface to a second terminal of the power source; moving the operating member gradually towards the inner surface to detect the emission of a signal generated by an emitting device interposed between one of the terminals and the inner surface, and corresponding to a condition in which initial contact is established between the operating member and the inner surface; and determining the position of the operating member at the instant the signal is emitted.

Abstract: The present invention provides a detection device, which comprises a light-emitting device for projecting a light source to a slotted mask. An optical detector is used to detect the light passing through the slots. A plurality of optical detection units are disposed in the optical detector. Each of the optical detection unit comprises an optical detection component for converting light into a current signal. The optical detection component is connected to a signal selection circuit via a current mirror circuit. When the current of one of optical detection units is maximal in all of the optical detection units and larger than a half of the total current, the optical detection unit will output a voltage signal of high voltage. Otherwise, it will output a voltage signal of low voltage. The present invention has the advantages of high resolution and high noise immunity.

Abstract: A compact position and velocity transducer having a high speed resolution and a fast speed response and that does not place much demand on the precision of the bearings. The transducer includes an optical encoder that, when assembled in motors, is assembled on a short protruding part of the rotor close to the torque-creating parts. The optical incremental encoder signals are fed both to a moderate frequency digital counter that counts 4 counts per basic encoder period and to an A/D-converter that samples and digitizes the primary encoder analog signals. A processor uses a linearization algorithm on the sampled and digitized signals that yields position information that is locally highly continuous.