Patent ID: 7276687
Filing Date: 2007-10-02
Classification: G01D

Abstract:
1. An optical encoder comprising: a mobile unit in which light-transmitting parts and light-shielding parts are alternately arrayed so as to be equal in width and equal in interval to one another, the light-transmitting parts being implemented by light-permeable parts or light-reflecting parts; a light-emitting part for emitting light toward the mobile unit; light-receiving parts for receiving light emitted from the light-emitting part via the light-transmitting parts of the mobile unit; and a move-information-signal generating part for, based on change quantities of the light which varies in response to motions of the mobile unit and which is received by the light-receiving parts, generating and outputting a plurality of move information signals which represent move information on the mobile unit and which are independent of one another, wherein the light-receiving parts are positioned in correspondence to a specified number of the light-transmitting parts and composed of a plurality of photodiodes provided to a number represented by a product of a number of move information signals and the number of the corresponding light-transmitting parts raised to a power, wherein the power is an integer greater than one, wherein the plurality of photodiodes constituting the light-receiving parts are arrayed such that an equal number of photodiodes are respectively assigned to regions each of which is composed of a light-transmitting part in the specified number of corresponding light-transmitting parts and a light-shielding part rearwardly neighboring the light-transmitting part in a moving direction of the mobile unit, wherein assuming that an interval of the light-transmitting parts in the mobile unit is 1 pitch, with respect to mutually neighboring two photodiode groups each of which is composed of a plurality of photodiodes and are allocated to each of the regions, an interval between a photodiode of one photodiode group closest to the other photodiode group and a photodiode of the other photodiode group closest to the one photodiode group, and an interval between mutually neighboring two photodiodes belonging to an identical photodiode group, are each a value resulting from dividing the pitch by a product of the number of the move information signals independent of one another and the number of the corresponding light-transmitting part raised to a power, wherein the power is an integer greater than one.