Displacement measurement apparatus

• US 6,414,751 B1
• Filed: 08/22/2000
• Issued: 07/02/2002
• Est. Priority Date: 08/24/1999
• Status: Expired due to Fees

• Current Assignee: Konica Corporation (Konica Minolta Inc.)
• Original Assignee: Konica Corporation (Konica Minolta Inc.)
• Inventors: Kurogama, Tatsuji, Arai, Norikazu, Banno, Makoto
• Primary Examiner(s): Pham, Hoa Q.
• Application Number:
  US09/643,252
• Time in Patent Office: 679 Days
• Field of Search: 356/600, 356/614, 356/622, 356/623, 356/624, 356/237.1, 356/237.2, 356/237.3, 356/237.4, 356/237.5, 356/237.6, 356/429-431, 250/559.29, 250/559.34, 250/559.42, 250/559.45
• US Class Current: 356/237.1
• CPC Class Codes: G01N 21/55 Specular reflectivity
• CPC Class Codes: G01N 21/94 Investigating contamination, e.g. dust G01N21/85 takes precedence
• CPC Class Codes: G06K 7/10762 Relative movement

Abstract

A surface displacement detecting apparatus for detecting a concave, a hole on a surface of a detection object, comprises a light shielding device provided in a direction crossing the surface of the detection object, a light irradiating device provided at one side of the light shielding device and to irradiate the detection object with light; a light receiving device provided at the other side of the light shielding device and to receive at least one of regular reflection light and diffuse reflection light from the surface of the detection object; and a conveyor to convey at least one of the detection object and the light irradiating device.

Claims

1. A surface displacement detecting apparatus for detecting a surface displacement due to a concavity, a convexity or a hole in a surface of a detection object, comprising:

a light shielding plate having an end portion;

a light irradiating device provided at one side of the light shielding plate and to emit a light beam toward the surface of the detection object;

a conveyor configured to convey at least one of the detection object and the light irradiating device relative to the other one in a conveying direction so that the surface of the detection object passes proximal to the end portion of the light shielding plate to define a gap between the surface of the detection object and the end portion of the light shielding plate, the light shielding plate being located in a direction perpendicular to the conveying direction; and

a light receiving device provided at an opposite side of the light shielding device, the light receiving device having a light receiving surface to receive the light beam having passed through the gap and sense an intensity of the light beam,

wherein the light beam reflected from the surface of the detection object is blocked by the light shielding plate or allowed to pass through the gap between the surface of the detection object and the end portion of the light shielding plate depending on the surface displacement of the detection object, and

wherein the light receiving device is configured to receive the light beam at a different portion of the light receiving surface depending on the surface displacement of the detection object so that the surface displacement is detected based on the portion of the light receiving surface and the intensity of the light beam.

2. The surface displacement detecting apparatus of claim 1, wherein the light irradiating device comprises a light source and an optical element to irradiate the detection object with the light emitted from the light source and the light receiving device comprises a condenser lens to condense at least one of regular reflection light and diffuse reflection light from the surface of the detection object and a light receiving element to receive the condensed light.

3. The surface displacement detecting apparatus of claim 2, wherein the light irradiating device shapes the light in a line and irradiates the detection object with the line-shaped light.

4. The surface displacement detecting apparatus of claim 3, wherein the light receiving elements are a PSD array in which n pieces of PSD are arranged in a direction along the line-shaped light or PD which is split into n pieces in a direction along the line-shaped light and m pieces in a direction perpendicular to along the line-shaped light, where n is an integer not less than 2 and into m is an integer not less than 1.

5. The surface displacement detecting apparatus of claim 2, wherein the optical element is a cylindrical lens.

6. The surface displacement detecting apparatus of claim 2, wherein the light irradiating device forms a plurality of spot light aligned in a straight line as the light and irradiates the detection object with the plurality of spot light.

7. The surface displacement detecting apparatus of claim 6, wherein the optical element is a micro lens array.

8. The surface displacement detecting apparatus of claim 6, wherein the light receiving elements are a PSD array in which n pieces of PSD are arranged in a direction along the plurality of aligned spot light or PD which is split into n pieces in a direction along the plurality of aligned spot light and into m pieces in a direction perpendicular to along the plurality of aligned spot light, where n is an integer not less than 2 and m is an integer not less than 1.

9. The surface displacement detecting apparatus of claim 2, wherein the surface displacement detecting apparatus detects the concavity, the convexity or the hole from a light receiving position on the light receiving device.

10. The surface displacement detecting apparatus of claim 9, wherein the light receiving position on the light receiving element displaces in a direction parallel to the light receiving element.

11. The surface displacement detecting apparatus of claim 2, wherein the light receiving device comprises a plurality of light receiving elements aligned in a straight line as the light receiving element or the light receiving element is split into a plurality of light receiving elements aligned in a straight line.

12. The surface displacement detecting apparatus of claim 2, wherein the light receiving elements are a PSD array in which n pieces of PSD are arranged in a predetermined direction or PD which is split into n pieces in a predetermined direction and into m pieces in a direction perpendicular to the predetermined direction, where n is an integer not less than 2 and m is an integer not less than 1.

13. The surface displacement detecting apparatus of claim 1, wherein the detection object comprises a flat surface and the concavity and the light irradiating device, the light shielding device and the light receiving device are arranged such that light reflected from the flat surface is shielded by the light shielding device and light reflected from the concave proceeds to the light receiving device.

14. The surface displacement detecting apparatus of claim 1, wherein the detection object comprises a flat surface and the concavity and the light irradiating device, the light shielding device and the light receiving device are arranged such that light diffused from the flat surface is shielded by the light shielding device and light diffused from the concave proceeds to the light receiving device.

15. The surface displacement detecting apparatus of claim 1, wherein a width of the light on the detection object is smaller than a width of the concavity, the convexity or the hole.

16. The surface displacement detecting apparatus of claim 1, wherein the light shielding device is shiftable in a direction crossing the surface of the detection object and the light shielding device is brought in contact with the detection object.

17. The surface displacement detecting apparatus of claim 1, wherein the light shielding device has an edge surface facing the detection object and is arranged to form a space between the edge surface and the detection object.

18. The surface displacement detecting apparatus of claim 1, wherein the detection object is a card having the concavity, the convexity or the hole.

19. The surface displacement detecting apparatus of claim 1, wherein a range of the displacement of the concavity, the convexity or the hole on the detection object is not larger than 1.0 mm.

20. The surface displacement detecting apparatus of claim 1, wherein the surface displacement detecting apparatus detects an amount of the surface displacement of the concavity, the convexity or the hole.

21. The surface displacement detecting apparatus of claim 1, wherein the light receiving device receives at least one of regular reflection light and diffuse reflection light from the surface of the detection object.