JPH0457462B2 - - 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 foreign object detection device is configured by arranging multiple light emitting elements and light receiving elements facing each other with the work table in between. 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 it changes the reflection direction of the light transmitted through the half mirror and irradiated by rotating the rotating mirror. A reflecting surface is arranged to reflect the reflected light of the rotating mirror that is irradiated across the plate surface and guide it to the detector via the mirror surfaces of the rotating mirror and the half mirror. The point at which the reflected light is directly irradiated is defined as an origin position, the range indirectly irradiated via the reflective surface is defined as a foreign object detection range, and this foreign object detection range is stored with reference to the origin position. It is something.

[Effect]

Therefore, according to the present invention, it is possible to initialize the foreign object detection range based on the origin position.

〔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.
Half mirrors 5a and 5b transmit the focused light (hereinafter referred to as a spot beam), rotating mirrors 6a and 6 reflect the spot beams transmitted through the half mirrors 4a and 4b.
b is a pulse motor which rotates the rotary mirrors 5a and 5b in a counterclockwise direction so that the direction of reflection of the spot beam reflected by the mirrors is counterclockwise; The reflective surfaces 7a and 7b are composed of a collection of prisms or glass beads, and the spot beams reflected while rotating on the rotating mirrors 5a and 5b are irradiated onto the reflective surfaces 7a and 7b at an angle of θ. It's summery. The spot beams irradiated onto the reflective surfaces 7a and 7b are reflected at the reflective surfaces,
It is guided and reflected by the mirror surfaces of half mirrors 4a and 4b via the mirror surfaces of rotating mirrors 5a and 5b, and is transmitted to the light receiving element 9 via convex lenses 8a and 8b.
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 is input into foreign object detection units 10 and 10, respectively, which have the same configuration. There is. The reflective surfaces 7a and 7b are arranged opposite to each other at different levels, so that the spot beam reflected by the rotary mirror 5a is irradiated onto the reflective surface 7a, and the spot beam reflected by the rotary mirror 5b is irradiated without crossing the reflective surface 7b. It's getting old.

FIG. 2 is a block diagram showing the internal configuration of this foreign object detection unit 10, and the electric signal inputted via the light receiving element 9a or 9b is inputted to the non-inverting input terminals of the comparators 11 and 12. comparators 11 and 12
The comparison voltages V ₁ and V ₂ (V ₁ > V ₂ ) are present at the inverting input of
is set. Further, the output of the comparator 11 is input to the clear terminal 13a of the counter 13 and the first input terminal 14a of the sequence logic 14, and the output of the comparator 12 is input to the second input terminal of the sequence logic 14. 14b. The counter 13 is designed to count the number of pulses generated by the pulse generator 15, and the counter 13 is designed to count the number of pulses generated by the pulse generator 15.
8 is in the closed state (in the initial setting mode), the input terminal 14b of the sequence logic 14
The count number of the counter 13 is stored in the memory 16 at the time when an "H" level signal is inputted through the comparator 12. Furthermore, when the signal input to the input terminal 14b of the sequence logic 14 switches from the "H" level to the "L" level, the count number at that time is stored in the memory 17. The count values stored in the memories 16 and 17 are reset when an "H" level signal is input to the input terminal 14a via the comparator 11.

On the other hand, when the mode selector switch 18 is in the open state (in the operating mode), the comparator 19 compares the count number in the counter 13 with the memory 1.
The counts stored in 6 and 17 are compared and the comparison result is sent to the sequence logic 14. That is, when the count value in the counter 13 becomes larger than the count value stored in the memory 16, the comparator 19 sends a signal to the sequence logic 14 informing the time to start foreign object detection, and the count value in the counter 13 becomes larger than the count value stored in the memory 16. When the count value becomes larger than the count value stored in the count value, a signal is sent to the sequence logic 14 to notify the end time of foreign object detection. Then, in the sequence logic 14, the signal input to the input terminal 14b becomes "L" from the input of the signal informing the start time of foreign object detection until the input of the signal informing the end time of foreign object detection.
When the level is reached, a foreign object detection signal is sent out through the output terminal 14c. In addition, 20
is an amplifier, which amplifies the pulses generated by the pulse generator 15 and supplies the amplified pulses to the pulse motor 6a or 6b.

Next, the operation of the optical foreign object detection device configured as described above will be explained. First, the operation of the rotating mirror 5a will be explained. The light emitted from the light projection source 2a shown in FIG. 1 is focused by a lens 3a to become a spot beam, passes through a half mirror 4a, and is irradiated onto a rotating mirror 5a. Now, this rotating mirror 5
Assuming that a is rotationally driven by a pulse motor 6a, the spot beam reflected by the rotating mirror 5a rotates counterclockwise while changing its reflection direction every moment. FIG. 3 is a waveform diagram 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. Then, as the rotating mirror 5a rotates, the light irradiated onto the light receiving element 9a is temporarily interrupted (point b in FIG. 3).
When the rotating mirror 5a rotates to the position shown in FIG. 4b, the spot beam reflected by the rotating mirror 5a begins to be irradiated onto the reflecting surface 7a, and passes through the mirror surfaces of the rotating mirror 5a and the half mirror 4a. The light is now received by the light receiving element 9a (point c in FIG. 3). 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 intensity of the light is directly reflected and received by the rotating mirror 5a. This light is received continuously until the rotating mirror 5a rotates further and its spot beam moves to the end of the reflecting surface 7a as shown in FIG. 4c (Fig. 4c). (point d in Figure 3).

That is, as the rotating mirror 5a rotates, a voltage signal having substantially the same waveform as that shown in FIG.
2 will be input. When a high level voltage signal (hereinafter referred to as the origin signal) is input at the origin position, the foreign object detection unit 10 sends out an "H" level signal from the comparators 11 and 12, and outputs a low level voltage signal. When a signal is input, only the comparator 12 sends out an "H" level signal. That is, the voltage V ₁ set at the inverting input terminal of the comparator 11 is
It is set lower than the voltage value input at point a in the figure and higher than the voltage value input at point c, and the voltage V ₂ set at the inverting input terminal of the comparator 12 is set at point c in Figure 3. It is set lower than the voltage value input in . here,
Now, when the mode changeover switch 18 is set to the initial setting mode, the count value in the counter 13 and the contents stored in the memories 16 and 17 are reset when the output of the comparator 11 reaches the "H" level (point a in Fig. 3). be done. And comparator 1
From the point when the output of the first
Point b in the figure) The counter 13 starts counting. Then, when the point c in FIG. 3 is reached and the comparator 12 starts sending out an "H" level signal, the count value of the counter 13 is stored in the memory 16. When the point d in FIG. 3 is reached, the output of the comparator 12 goes from the "H" level to the "L" level.
The count value of the counter 13 at that time is stored in the memory 17. That is, the foreign object detection range angle θ with respect to the origin position is stored in the memories 16 and 17 as a pulse count number, and the foreign object detection range is initialized. This initial setting of the foreign object detection range is performed when there is no foreign object on the work table 1, and is effective for detection when the foreign object 21 is on the foreign object detection start line e as shown in FIG.

That is, when the mode changeover switch 18 is set to the operation mode and foreign object detection is performed, the rotating mirror 5a
The counter 13 starts counting from zero at the time when the point passes the origin position. The count value of this counter 13 is constantly compared in the comparator 19, and when it becomes equal to the count value stored in the memory 16, the sequence logic 14
A signal is sent to notify the time to start detecting foreign objects.
Therefore, the spot beam reflected by the rotating mirror 5a is irradiated onto the foreign object 21 and scattered, and the spot beam is reflected by the light receiving element 9.
Even if the reflected light indicating the time to start detecting a foreign object is not incident on a, it is possible to determine that the time is the time to start detecting a foreign object, and the comparator 1 at this time
2, the sequence logic 14 sends out a foreign object detection signal from its output terminal 14c, and the presence of a foreign object is recognized using this foreign object detection signal. In other words, by initially setting the foreign object detection range based on the origin position, a foreign object on the foreign object detection start line e can be definitely recognized as a foreign object, eliminating the possibility of misidentification accidents. .

Furthermore, in the foreign object detection device according to this embodiment, the initial setting of the foreign object detection range can be automatically changed each time according to the length of the work table 1, and foreign object detection on work tables of various lengths can be performed. It has the excellent effect of being able to easily respond to. That is, as shown in FIG.
When the distance l ₁ from the center of the reflection surface 7a to the reflective surface 7a increases, for example, to l ₂ , the foreign object detection range angle θ becomes smaller to θ ₁ . For this reason, the foreign object detection range set in the foreign object detection unit 10 shown in FIG. A new number of pulses based on the origin position is stored in , and the foreign object detection range is automatically initialized according to the foreign object detection angle θ ₁ .

In this embodiment, the operation of only the rotary mirror 5a has been described, but it goes without saying that the operation of the rotary mirror 5b is the same as that of the rotary mirror 5a, and the shaded area in FIG. This is the surface of the foreign object detection plate in the example. Further, in this embodiment, a part of the work table 1 is used as the foreign object detection plate surface, but the entire area may be configured as the foreign object detection plate surface, and the peripheral area of the work table 1 It goes without saying that the foreign object detection range may also include the above.

〔Effect of the invention〕

As explained above, according to the optical foreign object detection device according to the present invention, the reflection direction of the light transmitted through the half mirror is varied while rotating the rotary mirror, and the A reflecting surface is arranged to reflect the reflected light of the rotating mirror that is irradiated across the plate surface and guide it to the detector via the mirror surfaces of the rotating mirror and the half mirror. The point at which the reflected light is directly irradiated is defined as an origin position, the range indirectly irradiated via the reflective surface is defined as a foreign object detection range, and this foreign object detection range is stored with reference to the origin position. Therefore, it is possible to initialize the foreign object detection range based on the origin position.
Foreign matter on the foreign matter detection plate surface can be detected with high accuracy in a simple manner without arranging a large number of light emitting/light receiving elements at close intervals as in the conventional method.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the optical foreign object detection device according to the present invention, FIG. 2 is a block diagram showing the internal configuration of a foreign object detection unit used in this foreign object detector, and FIG. 3 is a block diagram showing the internal configuration of a foreign object detection unit used in this foreign object detector. FIG. 4 is a waveform diagram showing the intensity of light received by the light receiving element of the device; FIG. 4 is a plan view showing the relationship between the rotational position of the rotating mirror and the direction of reflection of the spot beam reflected by the rotating mirror; FIG. FIG. 2 is a plan view showing changes in the foreign object detection range angle when the distance from the center of the rotating mirror to the reflecting surface changes. 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
...Foreign object detection 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. and 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 origin position is defined as the point in time when the mirror surface of the half mirror is directly irradiated with the reflected light of the rotating mirror. An optical foreign object detection device characterized in that an area indirectly irradiated via a reflective surface is defined as a foreign object detection range, and this foreign object detection range is stored with reference to the origin position.