JPH0457463B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical foreign object detection device suitable for use in detecting foreign objects on and around work tables in industrial machines such as NC equipment. .

[Conventional technology]

Conventionally, in some automation equipment such as NC equipment, in order to detect foreign objects on the work table, a plurality of light emitting elements and light receiving elements are placed facing each other with the work table in between to form a foreign object detection device. are doing.

[Problem that the invention seeks to solve]

However, according to such a foreign object detection device, the foreign object detection performance is determined by the spacing between a pair of adjacent light emitting elements and light receiving elements. This resulted in an extremely expensive detection device.

[Means for solving problems]

The present invention has been made in view of these problems, and includes a rotating mirror that rotates and changes the direction of reflection of light transmitted through a half mirror, and a rotating mirror that is arranged adjacent to the surface of a foreign object detection plate. It has a reflecting surface that reflects the reflected light from the rotating mirror that is irradiated across the plate surface and guides it to the detector via the rotating mirror and the mirror surface of the half mirror, and the rotating mirror reflects the light on the mirror surface of the half mirror. First and second optical foreign object detection means whose origin position is the point at which the light is directly irradiated are arranged opposite to each other with the foreign object detection plate surface interposed therebetween, and the origin of the rotating mirror of the first optical foreign object detection means is The time point at which the rotating mirror of the second optical foreign object detection means passes the origin position is determined based on the time point at which the second optical foreign object detection means passes the origin position.

[Effect]

Therefore, according to the present invention, the time when the rotating mirror of the first optical foreign object detection means passes the origin position and the time when the origin position of the rotating mirror of the second optical foreign object detection means passes are shifted in an arbitrary relationship. be able to.

〔Example〕

Hereinafter, the optical foreign object detection device according to the present invention will be explained in detail. FIG. 1 is a block diagram showing one embodiment of this optical foreign object detection device. In the same figure, 1
is a work table for industrial machinery such as NC equipment,
2a and 2b are light projection sources, 3a and 3b are convex lenses that converge the light emitted from the light projection sources 2a and 2b, and 4a and 4b are lenses 3a and 3b.
5a and 5b are rotating mirrors 6a and 6b that reflect the spot beams transmitted through the half mirrors 4a and 4b (hereinafter referred to as spot beams);
A pulse motor rotates the rotating mirrors 5a and 5b and rotates the direction of reflection of the spot beam reflected by the mirrors in a counterclockwise direction.Reflecting surfaces 7a and 7b are placed opposite to each other with the work table 1 in between. The reflective surfaces 7a and 7b are constructed by collecting prisms or glass beads, and the spot beams reflected while rotating on the rotating mirrors 5a and 5b cross the upper surface of the work table 1 and are irradiated onto the reflective surfaces 7a and 7b. It is becoming more and more common. The spot beams irradiated onto the reflective surfaces 7a and 7b are reflected on the reflective surfaces, guided to the mirror surfaces of the half mirrors 4a and 4b via the rotating mirrors 5a and 5b, and reflected, and reflected onto the convex lenses 8a and 8b. through the light receiving element 9
The light is received at points a and 9b. The light received by the light receiving elements 9a and 9b is converted into a voltage value according to the intensity of the light in these elements, and the input terminals 10a and 10
The signals are respectively input to the control unit 10 via the terminals b. The control unit 10 is adapted to control the rotation timing of the pulse motor 6b based on the input voltage signal. In this embodiment, the light projecting sources 2a and 2b, the convex lenses 3a and 3b,
Half mirrors 4a and 4b, rotating mirrors 5a and 5b, pulse motors 6a and 6b, reflective surfaces 7a and 7b, convex lenses 8a and 8b, and light receiving elements 9a and 9b detect the first optical foreign object detection means and the second optical foreign object. A detection means is configured. Further, the reflecting surfaces 7a and 7b are arranged opposite to each other at different levels, so that the spot beam reflected by the rotating mirror 5a is irradiated onto the reflecting surface 7a, and the spot beam reflected by the rotating mirror 5b is irradiated without crossing the reflecting surface 7b. It's getting old.

Next, the operation of the optical foreign object detection device configured as described above will be explained. That is, to explain the operation of the first optical foreign object detection means, the light emitted from the light projection source 2a is focused by the lens 3a, becomes a spot beam, passes through the half mirror 4a, and is irradiated onto the rotating mirror 5a. Ru. Assuming that the rotating mirror 5a is rotationally driven by the pulse motor 6a, the spot beam reflected by the rotating mirror 5a rotates counterclockwise while changing its reflection direction every moment. FIG. 2 is a waveform chart showing the intensity of light received by the light receiving element 9a as the rotating mirror 5a rotates. That is, at the point when the reflective surface of the rotating mirror 5a becomes approximately perpendicular to the incident spot beam as shown in FIG. (point a in Figure 2),
Thereafter, as the rotating mirror 5a rotates, the light receiving element 9
The light irradiated to a temporarily stops (b in Figure 2).
point). When the rotating mirror 5a rotates to the position shown in FIG. 3b, the spot beam reflected by the rotating mirror begins to be irradiated onto the reflecting surface 7a.
The light is received by the light receiving element 9a via the mirror surfaces of the rotating mirror 5a and the half mirror 4a (point c in FIG. 2). At this time, the intensity of the light received by the light receiving element 9a is such that the spot beam reflected by the rotating mirror 5a is incident indirectly via the reflecting surface 7a, so the spot beam is directly reflected by the rotating mirror 5a and received. This light continues to be received until the rotating mirror 5a rotates further and its spot beam moves to the end of the reflecting surface 7a as shown in FIG. 3c (Fig. 3c). d in Figure 2
point). That is, as the rotating mirror 5a rotates, a voltage signal having substantially the same waveform as that shown in FIG. The point in time when is inputted can be known as the point in time when the rotating mirror 5a passes the origin position.

The above has described the operation of the first optical foreign object detection means, but it goes without saying that the same applies to the operation of the second optical foreign object detection means including the rotating mirror 5b.
is adapted to control the rotation timing of the pulse motor 6b with reference to the time point when the rotating mirror 5a passes the origin position, and determine the time point when the rotating mirror 5b passes the origin position. FIG. 4a shows the input terminal 10 of the control unit 10 as the rotating mirror 5a rotates.
FIG. 4b shows the voltage waveform input to the input terminal 10b as the rotating mirror 5b rotates. That is, the control unit 10 controls the rotation timing of the pulse motor 6b so as to shift the timing of the origin signal input to the input terminal 10b by an angle of θ based on the origin signal input to the input terminal 10a. There is. In this embodiment, after the first optical foreign object detection means finishes searching for a foreign object on the work table 1 while irradiating the reflective surface 7a with a spot beam, the second optical foreign object detection means searches for the foreign object on the work table 1 after a predetermined period of time. The beam is irradiated onto the reflective surface 7b to search for foreign objects in the remaining area of the work table 1.
corner is set. By using such a method of searching for foreign objects, it is possible to eliminate optical interference between the spot beams, and accurate detection of foreign objects can be performed. Furthermore, by knowing whether the first foreign object detection means has detected a foreign object or whether the second foreign object detection means has detected a foreign object, it is possible to confirm the area where the foreign object exists, and furthermore, it is possible to check the area where the foreign object is present. Another pair of rotating mirrors 5c and 5d are arranged facing each other on a diagonal line that intersects the straight line connecting the center of the mirror and the center of the rotating mirror 5b, as shown in FIG. 5, to divide the foreign object detection area on the work table 1. By detecting the foreign matter, it is possible to confirm the foreign matter existing region with even higher accuracy.

Moreover, as shown in FIG.
Light receiving elements 9a, 9b, 9c, 9d corresponding to 5d
(9c and 9d are light-receiving elements added to accurately detect foreign matter existing regions) Processing circuits 11a, 11b, 11c, 1 each having a memory
1d, the information regarding the foreign object position is stored in the memory of this processing circuit, and after the information is synthesized in the synthesizer 12, it is compared with pattern data regarding various foreign objects stored in advance in the database 13. , it is possible to recognize not only the region where the foreign object exists, but also the shape of the foreign object, and more accurate foreign object detection can be performed.

Although this embodiment is configured to detect foreign objects on the work table 1, it goes without saying that the structure can also be configured to detect foreign objects around the work table. Since no detector is disposed, it can be used as a movement path for a robot arm or the like or a path for carrying in and out of processed parts, and has the advantage that work can be carried out without any hindrance.

〔Effect of the invention〕

As described above, the optical foreign object detection device according to the present invention includes a rotating mirror that rotates and changes the reflection direction of the light transmitted through the half mirror, and a rotating mirror that is arranged adjacent to the surface of the foreign object detection plate. It has a reflecting surface that reflects the reflected light from the rotating mirror that is irradiated across the plate surface and guides it to the detector via the rotating mirror and the mirror surface of the half mirror, and the rotating mirror reflects the light on the mirror surface of the half mirror. First and second optical foreign object detection means whose origin position is the point at which the light is directly irradiated are arranged opposite to each other with the surface of the foreign object detection plate sandwiched between them, and the origin of the rotating mirror of the first optical foreign object detection means is Since the time point when the rotating mirror of the second optical foreign object detection means passes the origin position is determined based on the time point when the second optical foreign object detection means passes the origin position, the time point when the first optical foreign object detection means passes the origin position and the second optical foreign object The time point when the detection means passes the origin position can be shifted in an arbitrary relationship, and the timing of the foreign matter detection operation of the first optical foreign matter detection means and the foreign matter detection operation of the second optical foreign matter detection means can be shifted, It is possible to eliminate mutual optical interference, and it is possible to eliminate multiple light sources and
Foreign matter on the foreign matter detection plate surface can be detected with high accuracy in a simple manner without arranging the light receiving elements at close intervals.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the optical foreign object detection device according to the present invention, FIG. 2 is a waveform diagram showing the intensity of light received by the light receiving element of this foreign object detection device, and FIG. 3 4 is a plan view showing the relationship between the rotational position of the rotating mirror and the reflection direction of the spot beam reflected by this mirror, and FIG. 4 is a time chart showing the voltage input to the control unit of this foreign object detection device via the light receiving element. , Fig. 5 is a plan view showing the arrangement of rotating mirrors that are additionally provided to further divide the foreign object detection area, and Fig. 6 is a block diagram for recognizing the shape of a foreign object from the voltage signal sent out from each light receiving element. FIG. 1...Work table, 2a, 2b...Light source,
4a, 4b...half mirror, 5a, 5b...rotating mirror, 6a, 6b...pulse motor, 7a,
7b... Reflective surface, 9a, 9b... Light receiving element, 10
...control unit.

Claims (1)

[Claims] 1. A rotating mirror that changes the direction of reflection of light transmitted through the half mirror while rotating, and a rotating mirror that is placed adjacent to a foreign object detection plate surface and that irradiates across the plate surface. It has a reflecting surface that reflects the reflected light and guides it to the detector via the mirror surfaces of the rotating mirror and the half mirror, and the point in time when the mirror surface of the half mirror is directly irradiated with the reflected light of the rotating mirror is the origin position. The first and second optical foreign matter detection means are arranged opposite to each other with the foreign matter detection plate surface interposed therebetween, and the first optical foreign matter detection means is rotated. An optical foreign object detection device characterized in that the time point at which the rotating mirror of the second optical foreign object detection means passes the origin position is determined based on the time point at which the mirror passes the origin point position.