Patent ID: 7655936

Claim:
An optical sensor comprising: at least one light emitting unit that emits a light on an incident light path toward an illumination object; a first light receiving unit that receives specular reflection light on a specular reflecting light path at an angle of specular reflection from the illumination object when the light is incident on the illumination object; a light condensing member provided on the incident light path; and a light diffusing member provided on the specular reflection light path; wherein a sum of the incident angle and the angle of specular reflection is 25 degrees or less; and 1 /a 1+1/( b 1 +b 2)=1 /f 1 or 1 /a 2+1/( b 1 +b 2)=1 /f 2 (1) in which a 1 is a distance from the light emitting unit to the light condensing member, b 1 is a distance from the light condensing member to the illumination object, a 2 is a distance from the light diffusing member to the first light receiving element, b 2 is a distance from the illumination object to the light diffusing member, f 1 is a focal distance of the light condensing member, and f 2 is focal distance of the light diffusing member.