Optical Scanning Type Photoelectric Switch

• US 20100193668A1
• Filed: 12/23/2009
• Published: 08/05/2010
• Est. Priority Date: 01/31/2009
• Status: Active Grant

• Current Assignee: Keyence Corporation (Keyence)
• Original Assignee: Keyence Corporation (Keyence)
• Inventors: Kawabata, Shinji
• Granted Patent: US 8,319,171 B2
• Time in Patent Office: Days
• US Class Current: 250/214.0SW
• CPC Class Codes: G01S 17/04 Systems determining the presence of a target
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/88 Lidar systems specially adapted for specific applications
• CPC Class Codes: G01S 2007/4975 of sensor obstruction by, e.g. dirt- or ice-coating, e.g. by reflection measurement on front-screen
• CPC Class Codes: G01S 7/4812 transmitted and received beams following a coaxial path
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/4868 Controlling received signal intensity or exposure of sensor
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating
• CPC Class Codes: G01S 7/51 Display arrangements
• CPC Class Codes: G01V 8/14 using reflectors
• CPC Class Codes: G01V 8/18 using mechanical scanning systems
• CPC Class Codes: G01V 8/20 using multiple transmitters or receivers
• CPC Class Codes: G05B 9/02 electric

Abstract

There is provided an optical scanning type photoelectric switch capable of facilitating control of holding a set detection sensitivity, wherein first and second reflection surfaces with different reflection factors are built as reference objects in the optical scanning type photoelectric switch, and arranged in a measurement invalid range in rotation of a scanning mirror, a light projection path, a light reception path, a laser light source LD and a light receiving element, which are used for scanning in the measurement area, are shared, and when a light reception intensity of the white second reflection surface is smaller than a “reference light reception intensity (white)”, a light projection driving section is controlled to increase the light projection intensity.

Claims

1. An optical scanning type photoelectric switch, which performs two-dimensional scanning with light to detect an object, and also measures a distance to the object to sense a two-dimensional position of the object, the switch having inside thereof:

a light projection path along which light emitted by a light projecting element is projected toward a measurement area through a trochoid first scanning mirror;

a light reception path along which reflected light reflected by the object is guided to a light receiving element through a second scanning mirror and received by the light receiving element; and

a reference object provided on the opposite side to the measurement area,

wherein the light projection path from the light projecting element to the first scanning mirror and the light reception path from the second scanning mirror to the light receiving element are shared so that light projected to the reference object and reflected by the reference object is received by the light receiving element.

2. The optical scanning type photoelectric switch according to claim 1, wherein the first scanning mirror and the second scanning mirror are a common scanning mirror, and light is projected and received using the same scanning mirror.

3. The optical scanning type photoelectric switch according to claim 1, having:

a storage device for storing reference light reception signal information, which is obtained at the time of projecting light to the reference object, when the detection sensitivity of the optical scanning type photoelectric switch is adjusted to the optimum; and

a detection sensitivity adjusting device capable of adjusting the detection sensitivity of the optical scanning type photoelectric switch,

wherein the detection sensitivity of the optical scanning type photoelectric switch is adjusted by the detection sensitivity adjusting device based upon actual light reception signal information, which is obtained at the time of projecting light to the reference object, and the reference light reception signal information.

4. The optical scanning type photoelectric switch according to claim 1, wherein the reference object is configured of a plurality of reflection surfaces with different reflection factors.

5. The optical scanning type photoelectric switch according to claim 4, further having;

a failure detecting device for determining failure when actual light reception signal information, which is obtained by projecting light to the reflection surface with a low reflection factor among the reference objects, is out of a predetermined range with the reference light reception signal information taken as a reference, based upon the light reception signal information obtained from the reflection surface with a low reflection factor and the reference light reception signal information; and

an output controlling device for shifting the optical scanning type photoelectric switch to a safety state when the failure detecting device determines failure.

6. The optical scanning type photoelectric switch according to claim 1, wherein laser light is emitted in pulse form from the light projecting element.