JP2989380B2 - Diffracted light detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diffracted light detecting device for irradiating a test object with a laser beam and detecting its diffracted light. The present invention relates to a diffracted light detection device most suitable for detecting, for example, a fluff in which one of thin wires is cut or elongated and protrudes from a thread-like body, such as a wire itself, an electric wire formed by twisting a large number of thin copper wires, or the like.

[0002]

2. Description of the Related Art In the process of weaving a cloth from yarn, the yarn is, for example, 6
The fabric is conveyed to the loom at a high speed of 000 m / min or the like, and the fabric is woven. In some cases, the yarn may break, and in this case, the fabric being manufactured will not only be a product, but also the production of the fabric will have to be interrupted. It has been desired to detect fluff effectively in the hair.

[0003]

The applicant has already filed an application for a fluff detector to meet the above demand (Japanese Patent Application No. 3-328495) as a prior application of the present application.
In this fluff detector, there is a problem how to reduce the influence of the 0th-order diffracted light having a greater light quantity than the diffracted light by the fluff, thereby improving the S / N ratio.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a diffracted light detection device capable of reducing the influence of the 0th-order diffracted light and performing detection with higher sensitivity.

[0005]

According to the present invention, there is provided a diffracted light detecting apparatus for irradiating a laser beam to a device under test, and a laser light source for irradiating the device with a laser beam. An optical sensor for receiving a laser beam diffracted by the object to be inspected and having an opening at an irradiation position of the 0th-order diffracted light; and a cylindrical member into which the 0th-order diffracted light applied to the opening is introduced. It is characterized by the following.

Here, the cylindrical member may be configured to trap the 0th-order diffracted light therein, or to guide the 0th-order diffracted light to a place where there is no influence on the optical sensor. A cylindrical member having openings at both ends so that the zero-order diffracted light introduced from the front end is emitted from the rear end, and further receives the zero-order diffracted light emitted from the rear end of the cylindrical member. And a monitor means for monitoring a ratio of a light amount of the zero-order diffracted light received by the second light sensor to a light amount of the laser light emitted from the laser light source. .

[0007]

According to the diffracted light detecting device of the present invention, the optical sensor has an opening at the irradiation position of the zero-order diffracted light, and the zero-order diffracted light irradiated to the opening is introduced into the cylindrical member. , 0th order diffracted light is prevented from adversely affecting the optical sensor.
Highly sensitive diffracted light detection with a high / N ratio becomes possible.

Here, instead of providing the cylindrical member, the space on the back side of the optical sensor may be devised so as to suppress the reflection and scattering of the zero-order diffracted light passing through the opening to the back side of the optical sensor. Conceivable. However, in this space, a board or the like on which a circuit connected to the optical sensor is usually mounted is often arranged, and it is difficult to devise measures to prevent reflection and scattering. In contrast, when a cylindrical member is provided, the space on the back side of the optical sensor can be used for various purposes without particularly worrying about light reflection or the like.

When the second optical sensor is disposed at the rear end of the cylindrical member and the light amount ratio is monitored, the light amount ratio is used to place the second light sensor on the optical path around the subject test object. It is possible to know the degree of contamination of the existing optical members, and thus, for example, it is possible to issue a warning when the detection of diffracted light becomes abnormal.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a fluff detector according to one embodiment of the present invention. A laser beam 2 emitted from a semiconductor laser 1 is converted into a parallel beam 2a by a lens system 3, and irradiates a yarn 10 extending in a direction perpendicular to the plane of FIG. 1 and conveyed at a high speed in that direction. This yarn is conveyed while slightly shaking in the vertical direction (arrows A and B directions) in FIG.
Occasionally a portion of the fluff 11 passes through this fluff detector.
After passing through the position of the yarn 10, the parallel light 2 a is condensed by the lens system 4 so that a Fraunhofer diffraction pattern is formed by the light 2 a irradiating the position of the optical sensor 20 with the yarn 10. Here, a pin font diode array is used as the optical sensor 20. The optical sensor 20 is provided with an opening 20a in the vicinity of the optical axis to which the zero-order light is irradiated. An opening 21a is provided concentrically with the opening 20a and is fixed to the substrate 21. Behind the openings 20a and 21a, there is provided a metal pipe 5 which is a cylindrical member according to the present invention. The zero-order light passing through the openings 20a and 21a is introduced into the metal pipe 5. This metal pipe 5
Has an elongated cylindrical shape with an outer diameter of 1.2 mm and an inner diameter of 0.8 mm, for example. The inner surface is painted black, and the laser light is suppressed as much as possible to capture this laser light inside the cylinder. Have been. The zero-order light condensed in the vicinity of the optical axis in this way has an extremely large amount of light as compared with the diffracted light that irradiates the optical sensor 20. The zero-order light is prevented from entering the optical sensor 20 as stray light, and fuzz detection with a high S / N ratio can be performed.

An optical sensor 25 is provided on the rear end side of the metal pipe 5, and a monitor means (not shown) controls the rear end of the metal pipe 5 with respect to the amount of laser light 2 emitted from the semiconductor laser 1. The ratio of the light amount of the zero-order light emitted from is monitored, and if this ratio falls below a predetermined value, a warning is issued. This means that the degree of contamination of the surfaces of the lenses 3 and 4 on the side of the thread 10 has reached a level that causes abnormal detection of the diffracted light of the fluff 11.

FIG. 2 is a view taken in the direction of arrows II-II in FIG. 2, the light sensor 20 is formed with two light receiving surfaces 20d and 20e extending vertically in the figure. Thread 1
As shown in FIG. 2, the diffracted light 30 due to the zero itself spreads in the vertical direction perpendicular to the horizontal direction in which the yarn 10 extends, so that the yarn 10 passes through the fluff detector on these two light receiving surfaces 20d and 20e. It is detected whether it is in the middle (inspection). The reason why the light receiving surfaces 20d and 20e are spread at a certain angle is to allow the yarn 10 to be conveyed with a slight inclination with respect to the fluff detector.

The light sensor 20 is connected to the light receiving surface 2.
It has two fan-shaped light-receiving surfaces 20b and 20c which are widened to the left and right in the figure so as to sandwich 0d and 20e from left and right, and the fluff 11 (see FIG. 1) extends in a direction different from the direction in which the main body of the yarn 10 extends. Therefore, the diffracted light 31 by the fluff 11 enters the light receiving surfaces 20b and 20c. Therefore, the presence of the fluff 11 is detected by detecting the incidence of light on the light receiving surfaces 20b and 20c. Here, the yarn 10
1 does not affect the diffraction pattern formed on the optical sensor 20 even if it trembles in the directions of the arrows A and B shown in FIG. 1, and thus the tremor does not become a detection error in this apparatus.

Here, a light receiving surface 20 for detecting fluff is used.
Since the amount of diffracted light applied to the b and 20c is extremely small as compared with the 0th-order light, in the case of the fluff detector of the prior application, 0
Although the next-order diffracted light wraps around the optical sensor for fluff detection and the S / N ratio deteriorates, it is difficult to detect diffraction light satisfactorily. By employing the configuration, such a disadvantage is improved.

FIG. 3 shows a honeycomb-shaped partitioning member 6 which can be provided in front of the light receiving surface of the light receiving member of FIG.
It is a perspective view shown with it. The partitioning member 6 has a structure to prevent the light that has entered each of the partitions from wrapping around to the adjacent partition. Therefore, when this partitioning member is provided on the front surface of the optical sensor 20, the zero-order light or the yarn 10 It is possible to prevent the diffracted light 30 from sneaking into the light receiving surfaces 20b and 20c due to itself, and to obtain a better S / N ratio.

Here, the detection of the fluff of the yarn 10 has been described as an example. However, the diffraction detection device of the present invention is not limited to the detection of the fluff of a yarn or other thin copper wire or the like. In addition, an optical device that needs to detect diffracted light can be generally applied.

[0017]

As described above, since the optical sensor has an opening at the irradiation position of the 0th-order diffracted light and is configured to introduce the 0th-order light diffracted light irradiated to the opening into the cylindrical member, Highly sensitive diffracted light with a high S / N ratio for introducing the zero-order diffracted light into the cylindrical member can be detected.

If the optical sensor is provided with a partition member in which the optical path is partitioned into a large number of cylinders in front of the optical sensor, detection with a better S / N ratio becomes possible. Further, a second optical sensor is provided on the rear end side of the tubular member, and by monitoring the light amount ratio, the reliability of the detection of the diffracted light can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a fluff detector according to one embodiment of the present invention.

FIG. 2 is a view taken in the direction of arrows II-II in FIG.

FIG. 3 is a perspective view showing a honeycomb-shaped partition member together with a substrate.

[Explanation of symbols]

 Reference Signs List 5 metal pipe 6 partition member 10 thread 11 fluff 20 optical sensor 20a opening 20b, 20c light receiving surface 21 substrate 25 optical sensor

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Takashi Ota 1-16-1 Hakusan, Midori-ku, Yokohama-shi, Kanagawa Prefecture Ono Sokki Technical Center Co., Ltd. (56) References JP-A-4-95863 (JP, A (58) Fields surveyed (Int.Cl. ⁶ , DB name) G01N 21/89 G01N 21/47

Claims (2)

(57) [Claims] 1. A laser light source for irradiating a laser beam to an object to be inspected, and a laser light source arranged on a diffraction surface of the laser beam irradiating the object to be inspected to receive laser light diffracted by the object to be inspected.
A diffracted light detection device comprising: an optical sensor having an opening at an irradiation position of the next-order diffracted light; and a cylindrical member into which the zero-order diffracted light irradiated to the opening is introduced. And a cylindrical member having openings at both ends so that the zero-order diffracted light introduced from a front end of the cylindrical member is emitted from a rear end of the cylindrical member. A second optical sensor that receives the zero-order diffracted light emitted from the rear end, and a light amount of the zero-order diffracted light received by the second optical sensor with respect to a light amount of the laser light emitted from the laser light source. 2. The diffracted light detection device according to claim 1, further comprising a monitor for monitoring the ratio.