JPH02106835A - Optical detector - Google Patents

Abstract

PURPOSE:To easily perform the detection of an object by arranging a light shielding body corresponding to the diffraction pattern of a light beam at the time when the light beam is shielded by the object, on window for receiving the light beam of the light receiving part or on the front of the window. CONSTITUTION:There is provided a light shielding body 3 on the front of a window 4 for receiving the light beam 2 from a light receiving part 5. The light shielding body 3 is composed of a transparent plate 31 in a rectangular shape and an aluminum deposition film 32 opaque to the light beam 2 on the whole of the glass plate. The deposition film 32 is formed in a ladder shaped light transmission pattern 32 corresponding to the diffraction pattern 11 in such a way that the light beam 2 is shielded by the bright portion 11a of the diffraction pattern 11 and is transmitted through the dark portion 11b thereof. Thus, the light beam amount received from the light receiving part 3 is far different in whether or not the diffraction pattern is coincident with the light transmission pattern and thus the object can be easily detected.

Description

[Detailed Description of the Invention] [Industrial Application Field] In the field of so-called FA, such as automation and rationalization of factory production lines, it is essential to detect the presence or absence of an object or to confirm that the object has passed a certain point. Also, some facilities.

In order to confirm the safety of the device 9 during operation of a machine, etc., it is necessary to confirm whether or not its component parts are in a predetermined position.

In addition, there is an extremely large need for detection units for detecting the proximity of foreign objects and for detecting the presence or absence of objects in hazardous locations. The present invention is an optical detection device for detecting the presence or absence of an object, such as a transmission-type optical sound or switch, used in such fields by determining whether or not light is blocked by an object, especially a minute linear object. The present invention relates to a detection device capable of detecting a linear object (hereinafter referred to as a fine line), a minute spherical object, etc. with a simple electric circuit configuration.

[Conventional technology]

To detect an object, a transmissive photoelectric switch is often used in the past.Its configuration is as shown in FIG.

It consists of a light receiving part 5 facing the light projecting part I and receiving the light beam 2; the light receiving part 5 has a lens 6 which condenses the light beam 2;
A photoelectric conversion element 7 that photoelectrically converts the light condensed by the lens 6 and outputs an electric signal 7aV corresponding to the amount of received light, and an electric signal 7a.
The detection circuit 8 is composed of a detection circuit 8 that receives an input signal tLl. Then, the C1 detection circuit 8 detects the change in the electrical signal 7m caused by the object 9 or the light 12 blocking it, and performs a predetermined switch operation to output a binary signal 8a.
This detection circuit 8 generates a reference value VS and performs a predetermined comparison operation with respect to the reference value generation circuit 8I and the reference value Vs of the input signal 7a.
It consists of a comparison circuit 82 which outputs a judgment signal in response to this judgment signal, and a switch section 83 which outputs a τ signal 88 which performs the above-described switch operation in response to this judgment signal QJ.

Figure 2 C: Hey 1:1. Since the photoelectric switch is configured as described above, it is possible to detect the presence or absence of an object 9 blocking the light @2 by operating the switch section 83 f2.

[Problem to be invented or solved]

In the photoelectric switch of FIG. 2, the presence or absence of the object 9 is detected as described above.
- If it is colored, the object is 9 or very thin (one diameter 0.1+o+
If the fine line f1 of the object 9 blocks the light beam 2, the change in the received light t at the light-receiving section 5 is calculated to be about a factor of 2.6.τ2 Normally, this level of light reception The amount change is due to a change in the characteristics of the detection circuit 8C, so it is difficult to detect whether it is too small or the detection circuit 8C is unstable. That is, the photoelectric switch of FIG. 2 has the problem that if the object 9 is a fine line, the amount of light received by the light receiving section 5 may change or become smaller, making it difficult to detect the object 9.

For this reason, conventionally, when the object 9 is a fine line.

Behind this object 9), a line 2σ] diffraction pattern 10, which is the sum of the two lines shown in Figure 3, is detected by the line image sensor. In contrast to detecting the average light intensity of the pattern I, a line image sensor detects the average light intensity of the diffraction pattern I.
Since the light intensity at each part of the pattern 10 is detected, the presence of the pattern 10 can be detected at a higher degree than the former. ).

An optical detection device may be used that compares this detection result with the previously memorized 4"C color pattern and detects the presence or absence of the τ object 9. In this case, a method based on pattern knowledge is used. QJ that determines the presence or absence of an object.

Since the configuration of the detection circuit 8 is very complicated compared to the configuration of the optical detection circuit 8, it is difficult to manufacture such an optical detection device. 3
The horizontal axis XX indicates the spatial position in the direction orthogonal to the fine line 9, and the vertical axis indicates the relative strength of the line 9. Also, point O indicates the position of the axis of the fine line 9, and point B indicates the intensity of light when the fine line 9 does not exist.

The purpose of the present invention σ] is that when the object 9 is in the shape of a minute line, a minute sphere, or a circle, the odor detector is also designed to increase the change in the amount of light received by the light receiving section 5 (such as the detection circuit 8). It is an object of the present invention to provide an optical detection device that can easily detect an object 9 even with a simple electrical circuit.

[Means for solving problems]

Achieving the Queen's Purpose'''F71'According to the present invention,
A light projecting section that projects a coherent light beam; and a light receiving section that receives the light beam and performs a detection operation according to the result of the light reception; In an optical detection device that detects a filter object, τ,
A light shielding body corresponding to the diffraction pattern of the light beam formed when the object blocks the light beam is placed in the window of the light receiving section that receives the light beam or in front of this window, and an optical detection device is installed. shall be configured.

[Effect]

By configuring C as above, the bright part of the diffraction pattern will be blocked and the dark part of the diffraction pattern will be allowed to pass through. Since the amount of light received by the light receiving section can be significantly different depending on whether the pattern does not match the light transmission pattern or when it matches, the above-mentioned detection port can be used even if the object is minute or minute. It is possible to easily detect a single object using an electric circuit having a simple configuration as shown in line 8.

〔Example〕

FIG. 1 is a block diagram of a photoelectric switch 13 according to an embodiment of the present invention. The difference from Figure 2 is that a light shield 3 with the configuration shown in Figure 4 f is provided on the front of the light receiving section 50 that receives the light beam 2. As shown in FIG. 4, a rectangular transparent glass plate 3I and an opaque aluminum evaporated film 32 for each of the light beams 2C formed on the negative side of the glass 1. This vapor deposited film 32 is provided so as to form a ladder-like light transmitting pattern 12 corresponding to the diffraction pattern shown in FIG. Then, this light transmission pattern 12 is the bright part 11a'l of the diffraction pattern 11:! 'A pattern that blocks light and transmits the dark part 11b of 1 badan 11, and 1 diffraction pattern 111'! , distance C of 1 m in front of the fine line 9 and the light shielding body 3:
When the light ray 2 is orthogonally projected onto the light shielding body 3 and is placed at a position that coincides with the axis Y-Y of the light shielding body 3, the light ray 2 is diffracted by the fine line 9 t'tτ the light shielding body 3 is a diffraction pattern formed on the surface. In addition.

4. For convenience of explanation, the roof structure is shown in a plane where the light shielding body 3 or light transmitting pattern 12 can be seen.

Photoelectric switch! 3 is configured as described above and has 1 color, so
Now, as shown in Figure 1, I: has a diameter of 0.1-.
j6 tracing thin line 9 or light shielding body 30 axis Y-Y (see Fig. 5)
For convenience of explanation, C is also shown as t in the same way as the light shielding body 3 in FIG. ) in front of this light shielding body 3 in a posture parallel to
If it moves in the direction of the arrow Q on a plane P perpendicular to the imaginary light ray 2 at a distance of m, the light will be formed on the light shield 3. The kerosene position changes as shown in FIG. Therefore, when the first diffraction pattern tt matches the light transmission pattern 12 like the above pattern txt, it is blocked from entering the t light receiving section 5 by the bright part of the pattern ttt or the aluminum vapor deposited film 32 on the light shielding body 3. So.

When the amount of light received by the light receiving section 5 decreases and the diffraction pattern 11 becomes like the above-mentioned diffraction patterns 112 to 114 [ζ] When the light transmission pattern 12 does not match, these patterns 11
2 to 114, the light passes through the bright portion or the transparent portion of the light transmitting pattern 12, so the amount of light received by the light receiving portion 5 increases.1.
The result is a light transmission pattern! 1'3jII of the glass plate 31 with 2 t1''C: , The relationship between the position G on the virtual plane of the orthogonal projection of the fine line 9 onto the coincident virtual plane and the amount of light received by the light receiving section 5 W? Characteristic line 14 shown in No. 61i!!, l
Noyo51:, 7:cro. 68 in FIG. 6 is the light shielding body 3
This is the position of line III Y-Y.

In other words, as shown in Figure 5, the fine line 9 C: When moving, the light received ψW bs changes as shown in Figure 6. In this case, 1
In the state of the pattern 111 in which the diffraction pattern 11 and the light transmitting badan 121 are aligned, the light rays 20) due to the fine lines 9 are almost completely blocked by the light shielding body 3r: t1' and the light receiving part 5t: the incident L7r. 2nd diffraction pattern! 1 or the light transmitting pattern 12I, when they do not match, when they match, and σ] respectively C: difference ΔW in the amount of received light W, calculated result C: 10% or more. Shitakatsu-C, photoelectric switch 1
3L: Hey-C+technique, when crossing the minute line 9 or ray 2 [
: The change in the amount of light received ΔW is much larger than the change in the amount of light received by the photoelectric switch shown in Figure 2. t
Using an electric circuit with a simple configuration similar to that of the detection circuit 8, the detection can be easily performed.

Photoelectric switch 13C: Although the light passing pattern 12 is formed by vapor deposition of aluminum, in the present invention, the light transmission pattern 12 may be formed by vapor deposition of a material different from aluminum. In the present invention, the pattern 12'Ik may be formed by etching or punching a metal plate.

Furthermore, in the present invention, the temperature is 4.degree. For example, when a laser beam is used, an interference pattern 111. - Light area 11a and dark area ttb and σ)
This is advantageous because the difference ΔW in the amount of received light increases as a result. In addition, the above-mentioned embodiment has the light beam 2
Detects the light-blocking state of
This is a photoelectric switch that outputs a binary signal 8a, and the present invention is not limited to electrical devices that perform such switching operations. It goes without saying that the present invention can be applied not only to the above-mentioned fine wire 9 but also to minute spherical objects and circular objects (
it is obvious.

〔Effect of the invention〕

As described above, one aspect of the present invention includes a light projector that projects a coherent light beam, and a light receiver that receives the light beam and performs a detection operation according to the result of the light reception. Detection operation C: Basically, the light flux is blocked and the object is detected.The optical detection device -C1 The object or the light flux is blocked 1
6. A diffraction pattern of this light beam is formed. A corresponding light shielding member is placed in front of the window C, : which receives the light beam of the light receiving part, and an optical detection device t is constructed. .

For this reason, as shown above, C: structure @: T is used to block the bright part of the diffraction pattern and transmit the dark part of the diffraction pattern. What to do C: The amount of light received by the light receiving section can be made to be significantly different when the light transmitting pattern does not match and when the light transmitting pattern matches.
Even if the object is minute or minute, it is advantageous to be able to easily detect the object by using a 1M air circuit with a simple configuration such as the detection circuit 8 described above.

[Brief explanation of drawings]

Fig. fXl-1 is a block diagram of an embodiment of the present invention, Fig. 2 is a block diagram of a conventional photoelectric switch, Figs. Fig. 5 is an explanatory diagram of the operating principle of the embodiment shown in Fig. 1; It is a diagram. l...Light emitter, 2...Light beam, 3...
・Light blocking body, 4... Window, 5... Light receiving part,
9... Object, 10... Diffraction butter ÷ ÷ + ◆ r'-2 'Figure day 'Rin figure

Claims (1)

[Claims] 1) An object that includes a light projector that projects a coherent light beam, and a light receiver that receives the light beam and performs a detection operation according to the result of the light reception, and that blocks the light beam based on the detection operation of the light receiver. In an optical detection device that detects
Optical detection characterized in that a light shielding body corresponding to a diffraction pattern of the light flux formed when the object blocks the light flux is disposed in a window of the light receiving section that receives the light flux or in front of this window. Device.