Optical encoder and its manufacturing method

Abstract

An optical encoder comprises a sensor head including a light source and a photodetector and a scale that moves relative to the sensor head. The light emitted from the light source is reflected, transmitted or diffracted by the scale, and the reflected, transmitted or diffracted light is received by the photodetector to allow the sensor head to output a displacement signal. The sensor head includes a wiring substrate having electrodes formed thereon and on which the light source and photodetector are disposed at predetermined positions and a light transmitting material that covers the wiring substrate, light source, and photodetector. A side plane obtained by cutting the wiring substrate and light transmitting material at the same time in the direction substantially perpendicular to the light receiving surface of the photodetector serves as a reference position related to disposition of the components to be mounted on the wiring substrate.

1 . (canceled) 
   
   
       2 . An optical encoder comprising:
 a sensor head including:   at least one light source; and   at least one photodetector having a light receiving surface; and   a scale that moves relative to the sensor head, wherein the light emitted from the light source is reflected, transmitted or diffracted by the scale, and the reflected, transmitted or diffracted tight is received by the photodetector to allow the sensor head to output a displacement signal, wherein   the scale comprises a positioning section configured to be used for disposing the sensor head such that positional relationship between the scale and the sensor head becomes a predetermined position, and   the sensor head comprises:   a wiring substrate having a surface which faces the scale and a rear surface which is on the reverse side thereof, surface electrodes formed on the surface and rear surface electrodes formed on the rear surface, and at least either the light source and the photodetector provided on the surface;   a light transmitting material molded by resin seal being at least a part on a surface of the wiring substrate and covering at least either the light source and the photodetector; and   at least one of side planes obtained by cutting the wiring substrate and the light transmitting material at the same time in a direction perpendicular to the light receiving surface of the photodetector, wherein   at least either the light source and the photodetector is in a predetermined positional relationship with the side plane, and   by aligning the positioning section of the scale and the side planes of the sensor head with each other, the positional relationship between the scale and at least either the light source and the photodetector disposed on the wiring substrate becomes a predetermined position.   
   
   
       3 . The encoder according to  claim 2 , wherein the positioning section provided on the scale is an outer plane or an alignment pattern perpendicular to the long side of a grating pattern of the scale. 
   
   
       4 . The encoder according to  claim 3 , wherein the photodetector is a semiconductor IC with a circuit. 
   
   
       5 . The encoder according to  claim 4 , wherein the light source is disposed on the semiconductor IC. 
   
   
       6 . The encoder according to  claim 3 , wherein an electrical connection between surface electrodes and rear surface electrodes of the wiring substrate is formed on the wiring substrate excluding the side plane. 
   
   
       7 . The encoder according to  claim 6 , wherein through holes are drilled in the wiring substrate and the electrodes are placed in the through holes. 
   
   
       8 . The encoder according to  claim 3 , wherein the photodetector is disposed on the wiring substrate so that the long side of the photodetector becomes perpendicular to the side plane. 
   
   
       9 . The encoder according to  claim 8 , wherein the photodetector is a semiconductor IC with a circuit. 
   
   
       10 . The encoder according to  claim 9 , wherein the light source is disposed on the semiconductor IC. 
   
   
       11 . The encoder according to  claim 8 , wherein an electrical connection between surface electrodes and rear surface electrodes of the wiring substrate is formed on the wiring substrate excluding the side plane. 
   
   
       12 . The encoder according to  claim 11 , wherein through holes are drilled in the wiring substrate and the electrodes are placed in the through holes.