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Method of optically detecting position of object and position detecting apparatus using the method
| Details |
Inventors: Ishizuka, Koh; Nishimura, Tetsuharu; Tsukiji, Masaaki; Satoh, Chikara; Ishii, Satoshi;
Assignee: Canon Kabushiki Kaisha (Tokyo, JP)
Primary Examiner: Rosenberger; Richard A.
Assistant Examiner:
Attorney, Agent or Firm: Fitzpatrick, Cella, Harper & Scinto
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. |
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DETAILED DESCRIPTION Accordingly, an object of the present invention is to provide a method of optically detecting the position of an object, as well as a position detecting apparatus, capable of reproducing code information representing the position of the object by a simple procedure.
Another object of the present invention is to provide a position detecting apparatus having a compact construction and capable of detecting the position of an object with a high degree of resolution.
To these ends, according to one aspect of the present invention, there is provided a method of optically detecting the position of an object comprising the steps of arranging a plurality of arrays of data elements on the object in the direction of movement of the object, each array including a plurality of pieces of data elements indicative of position information concerning the position of the object; illuminating the array of data elements with a string of a beam which extends in the same direction as the array of data elements; and reproducing the position information by detecting light from the illuminated train of data elements.
According to another aspect of the present invention, there is provided a position detecting apparatus comprising: means for emitting a light beam; illuminating, with a string of the light beam, one of data element arrays which are arranged on the object in the direction of movement of the object and each having a plurality of data elements indicative of position information concerning the position of the object; and reproducing the position information by detecting the light from the irradiated data element array.
The term "direction of movement" is used to generally include the direction of movement such as a translational movement or rotation of the object.
Thus, the present invention can be embodied in the form of a linear encoder or a rotary encoder.
The data elements constitute a gray code (pattern) similar to that used in the absolute-type encoder described before Other features of the present invention will become clear from the following description of the preferred embodiments
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