Sensor using roof mirror/roof prism array scale, and apparatus equipped with the sensor

An optical encoder comprising:

• a light source means;
• a scale having a reflecting means that is arranged so as to oppose the light source means;
• and
• a light-receiving means that receives a reflected light beam from the scale,
• wherein the reflecting means of the scale has an optical characteristic where a divergent light beam from the light source means is divided into a plurality of wave surfaces after repeating reflection at least twice, and respective light beams obtained as a result of the division are made to overlap each other at an arbitrary position, and
• wherein when an air conversion optical path length from a light-emitting surface of the light source means to a substantial reflecting surface of the scale is referred to as gL, an air conversion optical path length from a light-receiving surface position of the light-receiving means to the reflecting surface of the scale is referred to as gP, a space between light-emitting points and a basic pitch of a light-receiving element group are referred to as P2, a pitch of the scale is referred to as P1, one of a center wavelength of an output peak value of a light beam emitted from the light source means and a wavelength of a center value obtained through integration of spectral distribution is referred to as λ, and a natural number is referred to as n, gaps are set at gL and gP which are determined so that the following relations are satisfied within a range of n<1:
• P2=2P1, gP=gL=2n(2P1)2/λ,
• wherein a peak position of received light intensity is set so as to coincide with the range.

An optical encoder comprising:

• a light source means;
• a scale having a reflecting means that is arranged so as to oppose the light source means;
• and
• a light-receiving means that receives a reflected light beam from the scale,
• wherein the reflecting means of the scale has an optical characteristic where a divergent light beam from the light source means is divided into a plurality of wave surfaces after repeating reflection at least twice, and respective light beams obtained as a result of the division are made to overlap each other at an arbitrary position, and
• wherein when an air conversion optical path length from a light-emitting surface of the light source means to a substantial reflecting surface of the scale is referred to as gL, an air conversion optical path length from a light-receiving surface position of the light-receiving means to the reflecting surface of the scale is referred to as gP, a space between light-emitting points is referred to as P2, a basic pitch of a light-receiving element group is referred to as P2, a pitch of the scale is referred to as P1, and one of a center wavelength of an output peak value of a light beam emitted from the light source means and a wavelength of a center value obtained through integration of spectral distribution is referred to as λ, gaps are set at gL and gP which are determined so that the following relations are satisfied within a range of 1.5<n<2.5:
• P2=2P1, gP=gL=2n(2P1)2/λ,
• wherein a peak position of received light intensity is set so as to coincide with the range.