LIBS-type object sorting device

Patent metadata

Field	Value
Publication number	US-11077467-B2
Application number	US-201716316879-A
Country	US
Kind code	B2
Filing date	Jul 4, 2017
Priority date	Jul 15, 2016
Publication date	Aug 3, 2021
Grant date	Aug 3, 2021

Abstract

An LIBS-type object sorting device includes a three-dimensional-shape measurement means that acquires a space-coordinate group of a top face of an object to be sorted in top view on a conveyor, an LIBS analyzing means that performs chemical composition analysis on the object to be sorted while irradiating the object to be sorted with laser light, and a conveying-path switching means that switches a conveying path of the object to be sorted, in this order. The device includes a computing means that determines an analyzing section on which the LIBS analysis is to be performed, and a control means that causes a beam position to move and causes, when detecting that the analyzing section has reached from a movement amount of the conveyor, based on the movement amount, a beam-focus position to move along the analyzing section while irradiating the laser light.

First claim

The invention claimed is:

1. A laser induced breakdown spectroscopy (LIBS) object sorting device configured to perform LIBS analysis on an object to be sorted while conveying the object to be sorted with a conveyor, the LIBS object sorting device being configured to sort the object to be sorted, the LIBS object sorting device comprising, with a traveling direction, a width direction, and a height direction of the conveyor defined as X, Y, and Z, respectively:
a three-dimensional-shape measurement means configured to repeatedly measure a cross-sectional shape of the object to be sorted at a cross-section-measurement YZ vertical face every predetermined time, the three-dimensional-shape measurement means being configured to acquire a space-coordinate group of a top face of the object to be sorted in top view on the conveyor with a reference origin on the object to be sorted as a reference;
an LIBS analyzing means including a width-direction movement means configured to move a beam position of laser light in a Y direction in a laser-movement YZ vertical face and a height-direction movement means configured to move a beam-focus position of the laser light in a Z direction in the laser-movement YZ vertical face, the LIBS analyzing means being configured to perform chemical composition analysis on the object to be sorted while irradiating the object to be sorted with the laser light;
a conveying-path switching means configured to switch a conveying path in the Z direction of the object to be sorted subjected to the chemical composition analysis, the three-dimensional-shape measurement means, the LIBS analyzing means, and the conveying-path switching means being provided in this order in the X direction;
a computing means configured to acquire the space-coordinate group of the top face on an analysis XZ vertical face including an analyzing point selected from the space coordinates, the computing means being configured to determine an analyzing section on which the LIBS analysis is to be performed; and
a control means configured to cause the width-direction movement means to move the beam position to the analysis XZ vertical face, the control means being configured to cause, when detecting that the analyzing section has reached the analysis XZ vertical face from a movement amount of the conveyor, based on the movement amount, the height-direction movement means to move the beam-focus position to the space coordinates along the analyzing section while causing the object to be sorted to be irradiated with the laser light,
wherein the space-coordinate group corresponds to a pixel of an image of the top face in top view on the conveyor,
the conveyor has an incremental encoder that outputs a pulse signal in response to a rotational amount of a driving motor, and
the control means causes the laser light to be irradiated along the analyzing section, with a counter number corresponding to the pulse signal, associated with the pixel of the image,
wherein the LIBS analyzing means is configured to irradiate the laser light at the object starting at a laser-irradiation start position (Ts) of the object located at a distance of an arbitrary count number (Obs) from a front edge of the object.

2. The LIBS object sorting device according to claim 1 , wherein the three-dimensional-shape measurement means acquires the space-coordinate group after detecting passage of the object to be sorted through the cross-section-measurement YZ vertical face, and additionally acquires a reference movement amount of the conveyor until the reference origin reaches the laser-movement YZ vertical face, and
the control means causes the beam position and the beam-focus position to move, based on the reference movement amount.

3. The LIBS object sorting device according to claim 2 , wherein the reference origin is a position at which the object to be sorted first reaches the cross-section-measurement YZ vertical face.

4. The LIBS object sorting device according to claim 1 , wherein the three-dimensional-shape measurement means includes a three-dimensional image camera having a laser projector that projects a cross-sectional-shape line of the object to be sorted at the cross-section-measurement YZ vertical face.

5. The LIBS object sorting device according to claim 4 , wherein the width-direction movement means and the height-direction movement means control a mirror angle and a lens focal length in an optical system of the laser light.

6. The LIBS object sorting device according to claim 3 , wherein a plurality of the objects to be sorted has respective parts disposed alongside in the Y direction, and
the computing means determines the respective analyzing sections of the objects to be sorted such that the analyzing sections are not disposed alongside in the Y direction.

7. The LIBS object sorting device according to claim 6 , further comprising:
a conveyance detecting means located upstream of the three-dimensional-shape measurement means in the X direction, the conveyance detecting means being configured to detect conveyance of the objects to be sorted, the conveyance detecting means being configured to start an operation of the three-dimensional-shape measurement means.

8. The LIBS object sorting device according to claim 7 , wherein the conveyance detecting means includes a photoelectric sensor.

9. The LIBS object sorting device according to claim 2 , wherein the three-dimensional-shape measurement means includes a three-dimensional image camera having a laser projector that projects a cross-sectional-shape line of the object to be sorted at the cross-section-measurement YZ vertical face.

10. The LIBS object sorting device according to claim 3 , wherein the three-dimensional-shape measurement means includes a three-dimensional image camera having a laser projector that projects a cross-sectional-shape line of the object to be sorted at the cross-section-measurement YZ vertical face.

Assignees

• Aist

Inventors

• Koyanaka Shigeki
• Kobayashi Kenichirou

Classifications

• G01B11/24

  for measuring contours or curvatures · CPC title

• B07C5/34

  Sorting according to other particular properties {(material testing per se G01N; quality control G07C3/14)} · CPC title

• B07C5/342 Primary

  according to optical properties, e.g. colour {(according to radiation transmittivity B07C5/3416)} · CPC title

• G01N21/718

  Laser microanalysis, i.e. with formation of sample plasma · CPC title

• G01N2021/8455

  and using position detectors · CPC title