Abstract: A manufacturing method for a code wheel for a rotary encoder is provided. The code wheel includes, in a central portion, a hole into which a rotary shaft of a rotary member is fitted and a code portion including a radial code pattern in a circumferential edge portion. The manufacturing method is configured to include the steps of forming the code portion and a reference circle in a plate so that the reference circle has a radius larger than a radius of the hole by a tolerance of deviation between a center position of the code portion and a center position of the hole and has a same center as that of the code portion; and forming the hole in the plate in which the code portion and the reference circle are formed, so as to be contained in the reference circle.

Abstract: An incremental coder in which stable positions of the coder are defined by multiples of an increment of the coder. The coder computes a difference between a binary word obtained for a current stable position and a binary word obtained for a previous stable position, and computes the value of variation of stable positions by determining the integer part of the division of the difference by the number of increments between two stable positions.

Abstract: Disclosed are various embodiments of high-speed, high-performance, low-noise optical encoders having various means for preventing undesired stray light from reaching light detectors incorporated therein. Structures employed to block stray light in the optical encoders include light barriers, air gap trenches, and coatings disposed between first and second sides of a substrate of the encoder. Also disclosed are compact single track optical encoders having a single dome lens disposed thereover, and dual track triple dome lens optical encoders. Methods of making such optical encoders are also disclosed.

Abstract: The present invention relates an optical three-dimensional coordinate sensor system and method thereof. A plurality of light-emitting modules produce a plurality of light signals, and then a plurality of reflected light signals reflected by an object are received by a plurality of photodetectors. After receiving the reflected light signals, the photodetectors generate a plurality of photocurrents. A plurality of active pixel circuits receive the photocurrents and transform the photocurrents to a plurality of reflective optical voltages. A plurality of differential amplifier circuits (DAC) compare the reflective optical voltages and the background voltages, and then output a plurality of DAC output voltages of the reflected light signals. Afterward, a processing module detects the DAC output voltages and uses an algorithm to calculate the top three of the DAC output voltages to determine the three-dimensional coordinate of the object.

Abstract: An angle sensor for detecting an out-of-round condition includes a disc supporting angle coder rigidly attached to a rotating shaft and at least one fixed optical system including a coherent light source emitting a beam interfering with the angle coder of the support disc in order to code its angular position, a collimator of the said beam before interference and a photo detector of the modulated beam after interference. In one embodiment, two optical systems arranged 90° from each other are employed. An alternative embodiment includes one optical system and the disc includes a circular track radially centred in at least one of its angular positions relative to the incident collimated light beam, and a radially orientated photo detector.

Abstract: An encoder configuration comprises a dual-modulation scale track pattern that provides a first intensity modulation component for producing periodic signals, and a second intensity modulation component for producing a long-range absolute signal. The dual-modulation scale track pattern increases the range-to-resolution ratio of the encoder without the use of additional scale tracks that would increase the width of the encoder components. The long-range signal may be encoded in the dual-modulation scale track pattern either by varying certain dimensions of pattern elements included in the scale track or by superimposing a layer including an optical density variation along on the track on pattern elements of similar areas. In either case, the net offset and/or amplitude levels of the associated signals are modified along the scale track. These modified offset and/or amplitude levels provide the basis for the long-range absolute signal.

Abstract: A sensor head for sensing light modulated by a moveable member, such as a code wheel or code strip, in an optical encoder. The sensor head has at least one monitor optical sensor and a primary optical sensor positioned to receive light modulated by a modulation track on the moveable member. The monitor optical sensor provides a monitor signal that is compared in a signal comparator to the output from the primary optical sensor to detect light at the primary sensor.

Abstract: An encoder is provided in which the absolute angle can be detected with high accuracy even when the irradiated position of light to be detected with respect to a scale is displaced from a reference, and a photodetecting device for an encoder used for such an encoder. In the encoder 1, by passing light to be detected through a straight-line light transmitting portion 17, a bright portion 19 to which the light to be detected is irradiated is formed in an area of a scale plate 11 containing mutually separate parts of arranged lines L1 and L2 and also a dark portion 20 to which no light to be detected is irradiated is formed in the other area.

Abstract: An optical encoder and method for measuring displacement information using an optical encoder uses an encoder member with multiple digital diffractive optic regions to optically diffract an incident beam of light to produce output beams of light having intensity distribution patterns, which are used to generate electrical signals that provide relative displacement information of the encoder member.

Abstract: In an absolute position detection type photoelectric encoder devised so as to detect a pseudorandom pattern disposed on a main scale by means of a plurality of imaging optical systems, assembling of the absolute position detection type photoelectric encoder is facilitated and production cost thereof is reduced by providing: a single light-receiving array element disposed on the imaging surfaces of the imaging optical systems, which incorporates a greater light-receiving array portion in the length measurement direction than the light-receiving range of the respective imaging optical systems; a window signal storing portion for storing a window signal showing a light-receiving range of the respective imaging optical systems; and a window signal comparison portion for obtaining signals corresponding to individual imaging ranges by comparing scanning signals of the light-receiving array element with window signals.

Abstract: A measuring element with a circular or linear track that encompasses a material measure and a number of sensors for scanning the track is disclosed. At least two scanning heads having the sensors are provided for scanning the track. The track of the measuring element has at least one first and a second partial track which are each provided with a first and a second grating period. For each grating period, one of the scanning heads is equipped with a sensor array that is adjusted to the grating period.

Abstract: A photoelectric encoder includes: a scale having a grating formed with a predetermined period Ps; and a detector head being movable relative to the scale and including a light source and a light receiving unit. In a configuration where light receiving elements in the light receiving unit output N-points light and dark signals (N is an integer of 3 or more), and where phases of the N-points light and dark signals are detected by a least-squares method to fit a sinusoidal function with fixed period to N-points digital signals digitized from the N-points light and dark signals, an N-points light and dark signal period P is set at an integral multiple of a data-point interval w of the N-points digital signals, and an overall length M of the light receiving elements is set at an integral multiple of the N-points light and dark signal period P. Thereby, position detecting errors occurring due to a stain of the scale and/or a defect in the grating can be reduced by simple computing.

Abstract: Disclosed are various embodiments of a reflective optical encoder system having at least three channels—two data channels and at least one index channel. The various configurations of reflective optical encoders disclosed herein permits very high resolution reflective optical encoders in small packages to be provided. In addition, the embodiments of the reflective optical encoder systems disclosed herein reduce problems associated with misalignment between code scales and light detectors, permit relatively simple electronic circuitry to be used to process outputs, and reduce manufacturing, assembly, integrated circuit and encoder costs. Methods of making and using such optical encoders are also disclosed.

Abstract: A scale for a photoelectric encoder effectively protects the base of the scale from corrosion, rust, and flaws. The scale includes a base, a light-absorbing layer including a DLC layer formed on at least one surface of the base, and light-reflecting layers with a higher reflectance than that of the light-absorbing layer with respect to light falling within a wavelength range and formed into a grating on the light-absorbing layer.

Abstract: A reflective metrological scale has a metal tape substrate and a scale pattern of elongated side-by-side marks surrounded by reflective surface areas of the substrate. Each mark has a furrowed cross section and may have a depth in the range of 0.5 to 2 microns. The central region of each mark may be rippled and darkened to provide an enhanced optical reflection ratio with respect to surrounding surface areas. A manufacturing method includes the repeated steps of (1) creating a scale mark by irradiating the substrate surface at a mark location with overlapped pulses from a laser, each pulse having an energy density of less than about 1 joule per cm2, and (2) changing the relative position of the laser and the substrate by a displacement amount defining a next mark location on the substrate at which a next mark of the scale is to be created.

Abstract: An optical encoder includes a scale which is installed on one member of which, displacement is detected, and a detecting head which is installed on the other member which moves relatively with respect to the one member, and is disposed facing the scale. A predetermined optical pattern in a direction of relative movement is provided, and the detecting head includes a light emitting section which irradiates a predetermined light on the scale, a light detecting section which includes a light receiving surface which receives light through the optical pattern, which is irradiated on the scale from the light emitting section, and which detects light distribution formed on the light receiving surface, a first light transmitting member which is disposed in an optical path between the light emitting section and the scale, and a second light transmitting member which is disposed in an optical path between the scale and the light detecting section.

Abstract: A mobile device that has a media path for receiving a sheet of print medium and a media drive mechanism for directing the print medium along the media path. An optical sensor in the device is positioned to receive first optical image information via a first optical pathway, and second optical image information via a second optical pathway. The first optical information being from an area of the media path and the second optical information being from an area external to the mobile device.

Abstract: A position-measuring device includes a scanning unit and a measuring graduation that is displaceable thereto in at least one measuring direction. The measuring graduation includes two incremental-graduation tracks extending in parallel in the measuring direction, between which a reference-marking track having at least one reference marking at a reference position extends. The scanning unit includes a first scanning device for generating the reference-pulse signal and a second scanning device for generating the incremental signals. To generate the incremental signals, a scanning beam acts at least once upon each incremental graduation in an incremental-signal scanning field.

Abstract: A method and apparatus for drug product tracking (or other pharmaceutical, health care or cosmetics products, and/or the packages or containers they are supplied with) using diffraction grating-based encoded optical identification elements 8 includes an optical substrate 10 having at least one diffraction grating 12 disposed therein. The grating 12 has one or more collocated pitches ? which represent a unique identification digital code that is detected when illuminated by incident light 24. The incident light 24 may be directed transversely from the side of the substrate 10 (or from an end) with a narrow band (single wavelength) or multiple wavelength source, and the code is represented by a spatial distribution of light or a wavelength spectrum, respectively, or a combination thereof. The encoded element 8 may be used to label any desired item, such as drugs or medicines, or other pharmaceutical or health care products or cosmetics.

Abstract: An encoder reset device and method that allows for an encoder to be automatically reset without operator intervention. A reset device of the present invention includes a microprocessor-based controller and associated programming for operating the reset device. As part of the automatic reset process, a reset device of the present invention is able to perform the connector pin jumpering necessary to resetting many encoders.

Abstract: An encoding and decoding method for a microdot matrix includes the steps of: forming a plurality of microdots by encoding based on Reflected Gray Codes in a data region included in each of a plurality of microdot blocks included in a microdot matrix, wherein the microdots corresponding to lower order bits of the Reflected Gray Codes are formed as the outmost microdots in the data region; scanning the microdot matrix to fetch an image and recognizing a microdot group in the date region of each microdot block in the image; and decoding a corresponded coordinate of the image on the microdot matrix according to the microdot block to which the microdot group containing lower order bits of the Reflected Gray Codes belongs.

Abstract: An optical encoder equipped with an origin detection apparatus has a scale provided with an optical grating, a plurality of light receiving elements that is provided in association with the pitch of the optical grating and movable relative to the scale and a light source that illuminates the light receiving elements with light through the scale. An optically discontinuous portion is provided in the optical grating of the scale, a change of a light beam that occurs over a certain length of section at the time when a light beam corresponding to the discontinuous portion is incident on the light receiving elements, a change occurring in that section is detected, calculation is performed, and an origin position is detected from the result of the calculation.

Abstract: A position-measuring device for generating a reference-pulse signal at at least one reference position includes a scanning unit and also a reflection-measuring graduation displaceable relative thereto in at least one measuring direction. The scanning unit for generating the reference-pulse signal includes a plurality of optical elements, including at least one imaging optics as well as at least two diaphragm structures, which are disposed in a diaphragm plane and have a plurality of diaphragm openings in each case. Furthermore, a light source as well as at least two detector elements are assigned to the scanning unit. The reflection-measuring graduation has a reference marking at the at least one reference position. It includes at least one set of first structure elements, which is arranged in the plane of the reflection-measuring graduation, perpendicular to the measuring direction, periodically at a first transversal periodicity.

Abstract: An encoder includes an encoder scale having an optical pattern of a prescribed cycle, and an encoder head configured to be displaced relative to the encoder scale. The encoder head includes a reference voltage generating circuit and a changing unit. The reference voltage generating circuit is configured to generate a reference voltage set to the center amplitude of an encoder signal when the output of the encoder is an encoder signal having periodicity of at least one phase. The changing unit is configured to change the reference voltage generated in the reference voltage generating circuit.

Abstract: Device for detection of out-of-round on an angle sensor including a disc supporting angle coding means rigidly attached to a rotating shaft and at least one fixed optical system including a coherent light source emitting a beam interfering with the angle coding means of the support disc in order to code its angular position, means for collimation of the said beam before interference and a photodetector of the modulated beam after interference. In accordance with one possibility, it includes two optical systems arranged 90° from each other. Alternatively, there is only one optical system and the disc includes a circular track radially centered in at least one of its angular positions relative to the incident collimated light beam, and a radially orientated photodetector.

Abstract: A photodiode detector array for an optical encoder includes a sequence of photodiodes having a pitch between adjacent photodiodes that alternates between a first pitch and a second pitch, the second pitch being different than the first pitch.

Abstract: A scale and a position-measuring device include the shifting of reference markings in graduation tracks, offset transversely with respect to the measuring direction, by fractions of the interval of the reference markings within a graduation track. It is thus possible to eliminate, or at least to markedly reduce, negative effects of the disturbance of the periodicity of a graduation track by the reference markings.

Abstract: The invention relates to displacement encoder for a movable shaft, comprising a sleeve (2) which is intended to be fixed in rotation to the shaft (3) and an encoding element (4) which is made from magnetizable polymer and which is solidly connected to the sleeve, said encoding element being equipped with an encoding zone (6) having at least one polarized mark. The aforementioned encoding zone of the encoding element is covered with a protective layer (10) which is made from a polymer having a surface abrasion resistance greater than that of the magnetizable polymer. The invention also relates to a device comprising one such encoder and to a production method thereof.

Abstract: A method for recording information from a surface of a substrate. The substrate is provided with a first position code and a second position code. The method comprises: (i) obtaining an image of the surface of the substrate using an optically imaging pen; (ii) determining whether the first position code or the second position code is present in the image; and (iii) determining the location of the pen. If the first position code is detected in the image, then the location is interpreted as handwritten input on the surface. Alternatively, if the second position code is detected in the image, then the location is used to determine if the pen is in a particular zone of the surface and a predetermined function associated with the zone is performed.

Abstract: In one aspect of the present invention, a device for sensing an absolute position of an encoded object, comprising: a position tracking module comprising: a track illumination module configured to illuminate the encoded object with one more light beams, and to detect one or more light beams resulting from said illumination of said encoded object; and an absolute position determinator configured to determine the absolute position of the encoded object based on said one or more light beams resulting from said illumination of said encoded object.

Abstract: A photoelectric encoder includes: a scale having a grating formed thereon along a measuring axis; a light source operative to emit light to the scale so as to form a light spot on the grating; and a photoreceiver operative to receive reflected light from the scale. The light source and the photoreceiver are disposed so as to be allowed to move relative to the scale at least in a direction along the measuring axis. The light source emits the light to the scale so that the photoreceiver receives the reflected light by the scale. The light source emits light with different wavelengths. The scale includes a plurality of reflection portions that respectively reflect the light with different wavelengths.

Abstract: A scale for a photoelectric encoder effectively protects the base of the scale from corrosion, rust, and flaws. The scale includes a base, a light-absorbing layer including a DLC layer formed on at least one surface of the base, and light-reflecting layers with a higher reflectance than that of the light-absorbing layer with respect to light falling within a wavelength range and formed into a grating on the light-absorbing layer.

Abstract: In a data region of each microdot block on a microdot matrix, a coordinate of each the microdot block on the microdot matrix is encoded into a plurality of microdots included by the data region according to an encoding method based on Reflected Gray codes. With the aid of a unique changed bit between any two consecutive Reflected Gray codes, an estimated coordinate of a frame, which is fetched by scanning the microdot matrix, on the microdot matrix, may still be decoded even if no complete microdot block is fetched within the frame.

Abstract: A mobile device is provided having a printhead for printing onto a print medium, a media path for directing the print medium past the printhead for printing, an optical sensor, a first optical pathway for directing first optical image information to the optical sensor from print medium within an area of the media path, and a second optical pathway for directing second optical image information to the optical sensor from print medium within an area external to the mobile device.

Abstract: A rotary encoder includes a shaft which serves as a rotation axis, a disc supporting plate fixed to the shaft, an encoder disc having a center hole, a first side face, and a second side face opposing the first side face, an elastic member contacting and pressing the second side face of the encoder disc, and a retaining member retaining the second side face of the encoder disc via the elastic member. The first side face is contacted with a surface of the disc supporting plate. The shaft is inserted into the hole. A belt conveyance apparatus includes an endless belt, a roller configured to rotate the endless belt, including a shaft and the rotary encoder. The rotary encoder is provided on the shaft of the roller. An electrophotographic image forming apparatus includes an image forming unit and the belt conveyance apparatus.

Abstract: An encoder with signal conditioning of an emitter drive signal is described. In one embodiment, the encoder includes a peak comparator, a pulse generator, a threshold comparator, and digital circuitry. The peak comparator outputs a peak comparator signal based on a comparison of an input sinusoidal signal stored at a first time with the input sinusoidal signal stored at a second time. The pulse generator determines a peak of the input sinusoidal signal based on the peak comparator signal. The threshold comparator compares a differential signal amplitude with a differential signal amplitude window at approximately the peak of the input sinusoidal signal. The differential signal amplitude is associated with the input sinusoidal signal. The digital circuitry generates an emitter modification signal in response to a determination that the differential signal amplitude is outside of the differential signal amplitude window.

Abstract: There is provided an encoder in which the absolute angle can be detected with high accuracy even when the irradiated position of light to be detected with respect to a scale is displaced from a reference. In the encoder 1, a bright portion 19 in which the light to be detected is irradiated to an area containing half rounds of arrangement lines L1 and L2 of a scale plate 11 is formed and also a dark portion 20 to which no light to be detected is irradiated is formed in the area excluding the bright portion 19 by passing the light to be detected through a rotating plate 8 having a toothed gear with a semicircular opening portion 17 formed therein.

Abstract: A high speed quadrature counter for use with a displacement measuring device is disclosed. The counter provides high speed counting by partitioning the tracking counter into a small fast tracking counter portion for the LSBs and a larger slow tracking counter portion for the MSBs. The fast tracking counter portion outputs a smaller number of bits according to a fast clock rate, while the slow tracking counter portion outputs a larger number of bits to update the remainder of the position at a slower clock rate. In various embodiments, the counter provides a corrected position value that has an effective timing within a few fast clock cycles of the time of the latch trigger signal. A corrected latched position circuit corrects an error that may otherwise be produced by the partitioning and the different clock rates of the fast and slow tracking counter portions.

Abstract: An encoder includes an encoder scale having an optical pattern of a prescribed cycle, and an encoder head configured to be displaced relative to the encoder scale. The encoder head includes a reference voltage generating circuit and a changing unit. The reference voltage generating circuit is configured to generate a reference voltage set to the center amplitude of an encoder signal when the output of the encoder is an encoder signal having periodicity of at least one phase. The changing unit is configured to change the reference voltage generated in the reference voltage generating circuit.

Abstract: A rotation-angle detecting apparatus detects a rotation angle of a rotating disc having radial markings, includes a plurality of detectors arranged at opposite sides of the axis of rotation of the disc and facing the markings, each of the detectors operable to detect a light beam from the markings, and outputting a pair of periodic signals having a 90-degree phase difference between the members of the pair; an analog-to-digital converter arranged to convert pairs of periodic signals from the detectors into pairs of digital signals; a digital signal processor configured to process the pairs of digital signals from the analog-to-digital converter; a binarization unit arranged to binarize the pairs of periodic signals from the detectors; and a counter arranged to count the pairs of periodic signals binarized by the binarization unit. The digital signal processor determines the rotation angle of the disc based on the pairs of digital signals from the analog-to-digital converter and count results from the counter.

Abstract: A reflection-based optical encoding apparatus for the detection of position and/or motion of a mechanical device includes an encoding medium having at least a first reflective portion, and an encoder housing having a light-emitting source and a light-detecting sensor embedded within, the encoder housing being placed in proximity to the encoding medium such that a functional light path can be established from the light-emitting source to the light-detecting sensor via the first reflective portion of the encoding medium. The encoder housing includes a first flat facet positioned between the light-emitting source and the encoding medium, the first flat facet having a first angle relative to a common geometric plane such that light passing from the light-emitting source to the encoding medium is refracted along a first angled path in a manner that the refracted light strikes a desired location of the encoding medium.

Abstract: An Analog to Digital (AD) converter and an AD converting method are provided. The AD converter includes one or more stators, and one or more actuators that move according to an input voltage. The digital output of the AD converter is determined based on an arrangement of the stators and the positions of the actuators relative to the stators. The AD converter can achieve high resolution and/or high speed with lower power consumption.

Abstract: Various embodiments of the present invention are related to photonic-interconnect systems for reading data from and writing data to memory cells of memory chips at approximately the same time. In one embodiment of the present invention, A photonic-interconnect system comprises a photonic interconnect coupled to a photonic device. The photonic interconnect is coupled to the memory chip and is configured to encode a first data set stored in the memory cells into a first set of electromagnetic signals at approximately the same time, decode a second data set encoded in a second set of electromagnetic signals at approximately the same time, and store the second data set in the memory cells. The photonic device is configured to transmit the first set of electromagnetic signals out from the photonic interconnect and transmit the second set of electromagnetic signals into the photonic interconnect.

Abstract: A method for compensating for encoder wheel eccentricity includes routing encoding module signals to a signal logic module when an encoder wheel is not at slew, averaging the encoding module signals, by using the signal logic module, to form averaged signals, when the encoder wheel is at slew, and generating an output signal from the averaged signals and the encoding module signals, by using the signal logic module.

Abstract: In the photoelectric encoder of the invention, as a light passing zone PZ of a movable object 21 travels by one pitch P, an output signal OUT2 of a second logical operation unit 26b comes to be delayed in phase by 45° with respect to an output signal OUT1 of a first logical operation unit 26a. Therefore, an output having a resolution two times higher than that of the movable object having a phase difference of 90° can be obtained, where the width of each of light receiving elements 22a-22d is (¼)P. Accordingly, the width of each of the light receiving elements can be made two times larger, compared with the case where the width of each of the light receiving elements is (?)P as in conventional optical encoders. Thus, the output strength of the detection signal can be increased, so that the S/N ratio can be improved.

Abstract: An optical signal is copressively sampled using an imaging system. The imaging system is created from a plurality of subimaging systems. Each subimaging system comprises a subaperture and a plurality of sensors. The optical signal is collected at each subaperture of the plurality of subimaging systems at a single time step. The optical signal is transformed into a subimage at each subimaging system of plurality of subimaging systems. The subimage includes at least one measurement from a plurality of sensors of each subimaging systems. An image of the optical signal is calculated from the sampling function and each subimage, spatial location, pixel sampling function, and point spread function of each subimaging system of the plurality of subimaging systems. The sampling function is selected so that the number of measurements from a plurality of subimages is less than a number of estimated optical signal values in the image.

Abstract: An optical encoder equipped with an origin detection apparatus has a scale provided with an optical grating, a plurality of light receiving elements that is provided in association with the pitch of the optical grating and movable relative to the scale and a light source that illuminates the light receiving elements with light through the scale. An optically discontinuous portion is provided in the optical grating of the scale, a change of a light beam that occurs over a certain length of section at the time when a light beam corresponding to the discontinuous portion is incident on the light receiving elements, a change occurring in that section is detected, calculation is performed, and an origin position is detected from the result of the calculation.

Abstract: A rotation-angle detecting apparatus detects a rotation angle of a rotating disc having radial markings, includes a plurality of detectors arranged at opposite sides of the axis of rotation of the disc and facing the markings, each of the detectors operable to detect a light beam from the markings, and outputting a pair of periodic signals having a 90-degree phase difference between the members of the pair; an analog-to-digital converter arranged to convert pairs of periodic signals from the detectors into pairs of digital signals; a digital signal processor configured to process the pairs of digital signals from the analog-to-digital converter; a binarization unit arranged to binarize the pairs of periodic signals from the detectors; and a counter arranged to count the pairs of periodic signals binarized by the binarization unit. The digital signal processor determines the rotation angle of the disc based on the pairs of digital signals from the analog-to-digital converter and count results from the counter.

Abstract: A method for determining the absolute value of a rotational angle includes imaging a continuous segment of a code track of a code carrier on a sensor array such that the sensor array generates a corresponding output signal. The code track includes a code provided over an angular range of 360°. The code contains a plurality of code words with each code word respectively corresponding to an angular value in the angular range. The output signal is correlated with a reference signal in a correlation filter to produce a correlation function signal. The reference signal is indicative of the code and the angular values corresponding to the code words. The correlation function signal is processed to determine the code word of the imaged segment of the code track as a function of the angular value where the output signal best coincides with the reference signal.

Abstract: An optical encoder device for a small-sized motor has a code wheel attached to a motor shaft which extends to the exterior of the motor through a bearing accommodated in a bearing-retaining section provided on an end bell of the motor, and a board on which a photosensor module is mounted such that an optical modulation track portion of the code wheel is positioned and disposed in a gap of the photosensor module. While a spacer is sandwiched between the end bell and the board, the motor, the spacer, and the board are fixed together by soldering a pair of motor terminals to a printed wiring portion of the board. The spacer has a generally U-shaped structure so as to allow fitting in position thereof from a direction orthogonal to the motor shaft.