An optical system for an optical encoder of the type having an optical code disc with a plurality of code tracks, and a multichannel photodetector for receiving modulated light from the code tracks, the optical system comprising a light source for producing a line of light, an optional collimating lens for receiving divergent rays of light from said light source and for directing the light in generally parallel rays toward the code disc, an objective lens disposed between the collimating lens and the code disc for focussing the light in a sharp line on the code disc, a housing for supporting the collimating lens and having a seat for receiving the objective lens, an aperture plate having an aperture slit therein aligned with the objective lens, and means for holding the aperture plate on the housing with the objective lens retained between the seat and the plate. Flanges may be provided on the housing to retain the aperture plate, preferably in a flexed position in engagement with the objective lens, which may be cylindrical, semicylindrical, or in the form of a doublet or a triplet. A grating may be substituted for the plate and the objective lens. In an alternative construction, the aperture plate may be molded into a cylindrical objective lens.
An unsealed optical encoder does not function properly in a fluid other than air because the optics do not function when interfaced with a medium having an index of refraction significantly higher than air. The collimating lens of an optical encoder has two refracting surfaces, at least one of the refracting surfaces being convex. An orthogonal cap of the present invention is attached over an optical encoder's collimating lens to create a sealed air cavity between the convex refracting surface of the collimating lens and the orthogonal cap. This placement of the orthogonal cap is such that the collimated light leaving the sealed air cavity may enter the surrounding medium at an angle that is normal to the surface of the medium, such as transparent oil, so that the collimated light does not bend even though the light is traveling from air to a much slower medium.
An optical encoder that accurately performs rotation while protecting a rotating disk from dust. The optical encoder comprises a shaft (5) supported by a bearing (6) in a housing (1), a rotating disk (8) fixed to the shaft (5), a light-emitting element (10) mounted on the housing (1), a photodetector element (12) mounted on a sub-board supported by the housing (1) for receiving the light passing through or reflected by the rotating disk (8), and a main substrate (13) mounted on the housing and provided with a circuit for determining the quantity of rotation or the angular position form the light received by the photodetector element (12). The housing (1) includes a holder (9), which as an annular cover (9a) engaged with the border of the main substrate (13) and a retainer (9b) formed on the cover (9a) for holding the light-emitting element.
A low height-profile rotary optical encoder having an improved coupling structure for coupling the code disc to the shaft for which positional information is desired wherein the coupling structure includes a coupling member having a shaft portion and an integral flexible coupling portion, a bearing structure for rotatably supporting the shaft portion within the encoder, the bearing structure and shaft portion each having a length which is substantially equal to one another, and the height of the encoder optics can be greater than the height of the bearing structure, and a base which is adapted to support the bearing structure, the shaft portion of the coupling member and the encoder optics in a common transverse section of the encoder and to house the flexible coupling portion of the coupling member wholly within the base.
A method of and apparatus for optically detecting the position or amount of movement of a movable object, in which a plurality of position data element arrays are provided on a scale attached to the object such that the arrays are arranged in the direction of movement of the object. A string of light beam such as a laser beam, which extends in the same direction as the position data element array, is made to illuminate one of the arrays, and the light reflected by or transmitted through the position data element array is received by a sensor array such as CCD sensor which produces a signal representing the pattern of arrangement of the data elements in the illuminated position data element array and indicating absolute position of the object, whereby the instant absolute position of the object is detected.
An optical encoder comprises a measuring section and a scanning grating plate. The measuring section comprises parallel light beam sources, light receiving elements located in opposition to the parallel light beam sources, converging devices disposed between the parallel light beam sources and the light receiving elements and a main grating plate arranged between the converging devices and the light receiving elements. The scanning grating plate is located between the main grating plate and the light receiving elements while allowing the scanning grating plate to move relative to the measuring section.
