Position detecting apparatus and measuring method
A position detecting apparatus includes a light-transmitting mirror that pivots around a pivot shaft and reflects measuring light from a light source; a light-receiving mirror that pivots around the pivot shaft and reflects returning light from an object; and a light-receiving element that receives the returning light from the light-receiving mirror. When the light-transmitting mirror and the light-receiving mirror are at rest, a first mirror angle between a mirror surface of the light-receiving mirror and a direction from the pivot shaft to the light-receiving element is larger than a second mirror angle between a mirror surface of the light-transmitting mirror and the direction.
1. A position detecting apparatus comprising:
a light-transmitting mirror that pivots around a pivot shaft and reflects measuring light from a light source;
a light-receiving mirror that pivots around the pivot shaft and reflects returning light from an object; and
a light-receiving element that receives the returning light from the light-receiving mirror, wherein
a first minor angle between a mirror surface of the light-receiving mirror and a direction from the pivot shaft to the light-receiving element is larger than a second minor angle between a mirror surface of the light-transmitting mirror and the direction, and
the mirror surface of the light-receiving mirror is tilted from the mirror surface of the light-transmitting mirror by an angle equal to half of a difference between a pivot amplitude of the light-receiving mirror and a pivot amplitude of the light-transmitting mirror.
2. The position detecting apparatus according to claim 1 , wherein the pivot shaft, the light source, and the light-receiving element are disposed along a same line in a direction perpendicular to the pivot shaft.
3. The position detecting apparatus according to claim 1 , further comprising:
a condenser lens between the light-receiving mirror and the light-receiving element, wherein
when the light-receiving mirror is at an end of a pivot range of the light-receiving mirror in a rotational direction in which the first minor angle increases, a luminous flux of a portion of the returning light deviates from the condenser lens.
4. The position detecting apparatus according to claim 1 , wherein the light-receiving mirror and the light-transmitting mirror are connected by two connecting shafts separated in a direction perpendicular to the pivot shaft.
5. The position detecting apparatus according to claim 1 , wherein the light-receiving mirror and the light-transmitting mirror are metal-film mirrors.
6. The position detecting apparatus according to claim 1 , further comprising:
a controller that calculates a distance from the position detecting apparatus to the object based on a phase difference between the light emitted from the light source and the returning light received by the light-receiving element.
7. A position detecting comprising:
a light-transmitting mirror that pivots around a pivot shaft and reflects measuring light from a light source;
a light-receiving mirror that pivots around the pivot shaft and reflects returning light from an object; and
a light-receiving element that receives the returning light from the light-receiving mirror, wherein
a mirror surface of the light-receiving mirror and a mirror surface of the light-transmitting mirror are parallel,
a first minor angle between a mirror surface of the light-receiving mirror and a direction from the pivot shaft to the light-receiving element is larger than a minor angle between the mirror surface of the light-receiving mirror and a direction from the pivot shaft to the light source, and
the mirror surface of the light-receiving mirror is tilted from the mirror surface of the light-transmitting mirror by an angle equal to a half amount of a difference between a pivot amplitude of the light-receiving mirror and a pivot amplitude of the light-transmitting mirror.
8. The position detecting apparatus according to claim 7 , further comprising:
a condenser lens between the light-receiving mirror and the light-receiving element, wherein
when the light-receiving mirror is at an end of a pivot range of the light-receiving mirror in a rotational direction in which the first minor angle increases, a luminous flux of a portion of the returning light deviates from the condenser lens.
9. The position detecting apparatus according to claim 7 , wherein the light-receiving mirror and the light-transmitting mirror are connected by two connecting shafts separated in a direction perpendicular to the pivot shaft.
10. A measuring method for measuring a distance from a position detecting apparatus to an object, the measuring method comprising:
reflecting, with a light-transmitting mirror, measuring light from a light source;
receiving, with a light-receiving mirror, returning light from an object incident and parallel to the measuring light reflected from the light-transmitting mirror;
reflecting to a first direction, with the light-receiving mirror, the returning light incident in a parallel manner to the measuring light reflected from the light-transmitting mirror; and
receiving, with a light-receiving element, the returning light, wherein
the first direction is tilted in a rotational direction in which a minor angle between the first direction and a second direction from the pivot shaft to a light-receiving element increases, and
wherein the light source and the light-receiving element are disposed around the pivot shaft tilted by an angle equal to a difference between a pivot amplitude of the light-receiving mirror and a pivot amplitude of the light-transmitting mirror.
11. The measuring method according to claim 10 , wherein while the light-transmitting mirror and the light-receiving mirror pivot, the reflecting, with the light-receiving mirror, in a position tilted from a pivot center to the rotational direction in which the minor angle decreases, reflects the returning light incident and parallel to the measuring light reflected from the light-transmitting mirror, to the second direction.
12. The measuring method according to claim 11 , wherein the light-receiving mirror, at an end of a pivot range of the light-receiving mirror in the rotational direction in which the minor angle decreases, reflects the returning light incident and parallel to the measuring light reflected from the light-transmitting mirror, to the second direction.
13. The measuring method according to claim 10 , wherein
the light source is disposed on the second direction, and
when the light-transmitting mirror and the light-receiving mirror are at rest, a mirror surface of the light-receiving mirror is tilted from a mirror surface of the light-transmitting mirror to the rotational direction in which the minor angle increases.
14. The measuring method according to claim 10 , wherein
the light source is disposed around the pivot shaft tilted from the direction of the light-receiving element to the rotational direction in which the minor angle increases, and
when the light-transmitting mirror and the light-receiving mirror are at rest, a mirror surface of the light-receiving mirror and a mirror surface of the light-transmitting mirror are parallel.
15. The measuring method according to claim 14 , wherein the light source and the light-receiving element are disposed around the pivot shaft tilted by an angle equal to a difference between a pivot amplitude of the light-receiving mirror and a pivot amplitude of the light-transmitting mirror.
16. The measuring method according to claim 10 , further comprising:
a condenser lens between the light-receiving mirror and the light-receiving element, wherein
when the light-receiving mirror is at an end of a pivot range of the light-receiving mirror in the rotational direction in which the minor angle increases, a luminous flux of a portion of the returning light deviates from the condenser lens.
17. The measuring method according to claim 10 , wherein the light-receiving mirror and the light-transmitting mirror are connected by two connecting shafts separated in a direction perpendicular to the pivot shaft.