Optical type position detecting device

• US 5,194,919 A
• Filed: 08/26/1991
• Issued: 03/16/1993
• Est. Priority Date: 08/28/1990
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Katayama, Hiroshi
• Primary Examiner(s): Evans, F. L.
• Application Number:
  US07/749,663
• Time in Patent Office: 568 Days
• Field of Search: 356/373, 356/375, 250/229, 250/231.1, 250/231.19
• US Class Current: 356/621
• CPC Class Codes: G11B 7/1381 Non-lens elements for altering the properties of the beam, e.g. knife edges, slits, filters or stops G11B7/1353 - G11B7/1369 take precedence

Abstract

An optical type position detecting device comprising a light source, and a light-receiving element for detecting a light beam emitted by the light source, a region on the light-receiving element whereon the light beam is incident having parallel boundaries, the boundaries extending in directions substantially corresponding to directions of relative displacement of the region and the light-receiving element, the relative displacement accompanying a displacement of a body. The relative displacement can be detected by detecting a change in area of the region using the light-receiving element. A magnitude of displacement of the body is proportional to a change in output of the light-receiving element since, irrespective of where the displacement of the body begins from, a contstant width of the region is maintained along a direction perpendicular with respect to the direction of the relative displacement. In other words, the displacement of the body can be accurately detected since linearity is achieved between the two.

Claims

1. An optical type position detecting device comprising:

a light source; and

a light-receiving element for detecting a light beam emitted by said light source;

said light-receiving element including a light-receiving section;

said light-receiving section having parallel sides, said sides being set to extend in directions substantially corresponding to directions of relative displacement of said light-receiving element and a region on the light-receiving element whereon the light beam is incident, a distance between said sides being set to be smaller than a size of a cross section of said light-receiving element of the light beam incident thereon so that boundaries of the region are formed by parts of said sides, a relative displacement being detected by using said light-receiving element to detect a change in area of the region, the change in the area accompanying the relative displacement.

2. An optical type position detecting device comprising:

a light source;

a light-receiving element for detecting a light beam emitted by said light source; and

region setting means for setting a region on said light-receiving element, whereon the light beam is incident, so that the boundaries of the region are parallel and for setting the boundaries to extend in directions substantially parallel to a direction of relative displacement of the region and said light-receiving element;

said relative displacement being detected by using said light-receiving element to detect a change in area of the region, the change in the area accompanying the relative displacement.

3. The optical type position detecting device as set forth in claim 2, wherein said region setting means consists of a light interrupting member disposed between said light source and said light-receiving element, in a path of the light beam;

said light interrupting member having an opening which includes parallel sides;

said sides extending in directions substantially parallel to a direction of the relative displacement of the region and said light-receiving element, a distance between said sides being set to be smaller than a size of a cross section of said light-interrupting member of the light beam incident thereon.

4. The optical type position detecting device as set forth in claim 2, wherein said region setting means consists of a filter member disposed between said light source and said light-receiving element, in a path of the light beam;

the filter member having a first section which allows the light beam to be easily transmitted and a second section which, compared to said first section, prevents the light beam from being transmitted easily;

said first section and said second section being separated by parallel boundary lines;

said boundary lines extending in directions substantially corresponding to the directions of the relative displacement, a distance between the boundary lines being smaller than a size of a cross section of said filter member of the light beam incident thereon.

5. The optical type position detecting device as set forth in claim 4, wherein a transmittance distribution of said first section is set so that the light beam transmitted through said first section has a uniform distribution of light intensity along the directions of the relative displacement.

6. An optical type position detecting device comprising:

a light source;

a light-receiving element for detecting a light beam emitted by said light source; and

a light interrupting member disposed between said light source and said light-receiving element, in a path of the light beam;

said light-receiving element being provided with a light-receiving section;

said light-receiving section having a first side which extends in a direction parallel to a direction of relative displacement of said light-receiving element, whereon the light beam is incident;

said light interrupting member being provided with a cutaway section having a second side which extends in a direction parallel to the direction of relative displacement, a distance between said first side an a projection of said second side on said light-receiving element being set to be smaller than a size of a cross section of said light-receiving element of the light beam incident thereon;

said relative displacement being detected by using said light-receiving element to detect a change in area of the region, the change in the area accompanying the relative displacement.

7. An optical type position detecting device comprising:

a light source;

a light-receiving element, provided with four light-receiving sections separated by two orthogonal parting lines, for detecting a light beam emitted by the light source; and

region setting means for setting two parallel pairs of boundaries to a region of said light receiving element whereon the light beam is incident, a relative displacement of said region and said light-receiving element being detected by comparing outputs of said light-receiving sections.

8. The optical type position detecting device as set forth in claim 7, wherein said region setting means consists of a light interrupting member disposed between said light source and said light-receiving element, in a path of the light beam;

said light interrupting member having an opening which includes two parallel pairs of sides, a distance between said sides of each of the parallel pairs being set to be smaller than a size of a cross section of said light-interrupting member of the light beam incident thereon.

9. The optical type position detecting device as set forth in claim 8, wherein two parallel pairs of the sides are orthogonal and two parallel pairs of the sides are respectively parallel to the two parting lines.

10. The optical type position detecting device as set forth in claim 7, wherein said region setting means consists of a filter member disposed between said light source and said light-receiving element, in a path of the light beam;

said filter member having a first section which allows the light beam to be easily transmitted and a second section which, compared to said first section, prevents the light beam from being transmitted easily;

said first section and said second section being separated by two parallel pairs of boundary lines, a distance between the boundary lines being smaller than a size of a cross section of said filter member of the light beam incident thereon.

11. The optical type position detecting device as set forth in claim 10, wherein two parallel pairs of the boundary lines are orthogonal and two parallel pairs of the boundary lines are respectively parallel to the two parting lines.

12. The optical type position detecting device as set forth in claim 10, wherein a transmittance distribution of said first section is set so that the light beam transmitted through said first section has a uniform distribution of light intensity along directions of the relative displacement.

13. The optical type position detecting device as set forth in claim 12, wherein two parallel pairs of the boundary lines are orthogonal and two parallel pairs of the boundary lines are respectively parallel to the two parting lines.