JP2000190374A - Silver streaking inspecting device for transparent plastic plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To objectively and simply inspect the silver streaking generated in a transparent plastic plate. SOLUTION: An inspecting device for quantitatively and automatically inspecting the silver streaking on a transparent plastic plate consists of a laser beam generating means, a condensing means for condensing laser beam to the transparent plastic plate, a scanning means for scanning condensed laser beam on the transparent plastic plate, a shading means for shading the laser beam transmitted through the transparent plastic plate, an operation means for calculating the quantity and position of the silver streaking from the detected quantity of refracted laser beam and a scanning position and an image processing means recording the calculated result obtained from the operation means on an image. In this case, the condensing means condenses laser beam on the transparent plastic plate so that the spot shape of the laser beam becomes an oval shape of which an aspect ratio (long diameter:short diameter) is 5:1-2:1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for inspecting a transparent plastic plate for silver stripes. More specifically, by irradiating the spot of the condensed laser light on a transparent plastic plate and scanning, and detecting the laser light refracted due to the silver strip, the silver strip is quantitatively and automatically inspected. It relates to a silver strip inspection device.

[0002]

2. Description of the Related Art A silver strip is a silver-like streak generated in the flow direction on the surface of an injection-molded resin molded product, and is also referred to as silver or silver wire. Usually, particles of unreacted components contained in the resin produced by the polymerization reaction rub against the mold surface during molding, and exhibit silver or white streaks in the flow direction. The silver strip is a kind of resin molding defect and is regarded as one of quality control items of the resin molded product. Further, the resin itself is also subjected to silver strip inspection as an index indicating the tendency of silver strip to be formed during molding.

Conventionally, silver strips have been inspected by visually counting the number of silver strips. However, the method of visually inspecting silver stripes requires a great deal of time and effort, and has a problem that the judgment criteria of the streak are significantly affected by the subjective judgment of the judge.

In order to solve such a problem, there has been proposed a method of electrically inspecting silver stripes. For example, Japanese Patent Application Laid-Open No. 2-72920 discloses that an image sensor is used to scan the surface of an injection-molded resin molded product, perform image processing on an obtained output signal, and determine the area of a silver strip existing on the surface. Numerical values are obtained in correspondence with the number of pixels of the image sensor, and are compared with a preset reference value to reliably detect and discharge defective molding products having a large number of silver strips, and to perform injection molding. An injection molding control method that enables proper control of conditions is described.

However, even with such a technique, it is difficult to detect silver stripes in a transparent resin with a charge-coupled device (CCD) image sensor. Was something.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for objectively and easily inspecting a silver strip generated on a transparent plastic plate.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies on the optical characteristics of silver strips generated on a transparent plastic plate, and as a result, when a laser beam was irradiated on the transparent plastic plate, The present inventors have found that although the light passes through the transparent plastic plate straightly, the light is refracted when the light passes through the silver strip, thereby completing the present invention.

That is, the present invention provides an apparatus for quantitatively and automatically inspecting silver strips on a transparent plastic plate,
The inspection apparatus includes (a) a laser beam generating means, (b) a light condensing means for condensing the laser light on a transparent plastic plate, and (c) a condensing laser light on the transparent plastic plate. Scanning means for scanning, (d) shielding means for shielding the laser light transmitted through the transparent plastic plate,
(E) laser light detecting means for detecting the refracted laser light leaked from the shielding means, (f) calculating means for calculating the amount and position of the silver strip from the detected refracted laser light amount and the scanning position, and It is an object of the present invention to provide a silver strip inspection apparatus, comprising: an image processing means for recording a calculation result obtained by a calculation means on an image.

Further, in the present invention, the light condensing means may change the spot shape of the laser light condensed on the transparent plastic plate into an oval having an aspect ratio (major axis: minor axis) of 5: 1 to 2: 1. It is intended to provide the above-mentioned silver strip inspection apparatus, wherein the light is condensed so as to be as follows.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The silver strip inspection apparatus of the present invention will be described below in detail. (Transparent plastic plate) In the silver strip inspection method of the present invention, the transparent plastic plate is a transparent resin plate or a resin film obtained by injection-molding a synthetic resin. Also,
Usually, silver stripes occur on the front and back of a resin plate or a resin film obtained by injection-molding a resin. Alternatively, the silver strip generated on the back surface can be inspected. However, when silver stripes generated on the front surface are inspected, if the silver stripes on the rear surface are significantly large, the inspection can be performed at the same time.

(Silver Strip Inspection Apparatus) (i) Laser Light Generating Means, Scanning Means The laser light generating means, focusing means, and scanning means used in the present invention are not particularly limited, and are known in the art. Or known methods can be used.

(Ii) Focusing Means The focusing means of the laser beam used in the present invention is not particularly limited, but is usually a lens. In the focusing means, the shape of the focused laser beam spot is usually 10 to 100 μm, which is almost the same as the width of a silver strip. In addition, since silver stripes are usually generated along the resin flow direction during injection molding, they are long in that direction and usually exist in a linear shape having a length of several mm. Therefore, in the light condensing means, the shape of the spot of the condensed laser light can be detected with high sensitivity by making it a long ellipse orthogonal to the scanning direction of the laser light. The shape of the spot has an aspect ratio (ratio of major axis to minor axis) of 5: 1 to 2: 1, preferably 4: 1.
３3: 1. When the aspect ratio is out of the range of 5: 1 to 2: 1, there is a problem that the sensitivity is reduced.

(Iii) Shielding means The shielding means used in the present invention is not particularly limited as long as it does not transmit laser light. However, in the present invention, it is important that the shielding means can completely shield the spot of the laser beam transmitted through the transparent plastic plate. The shape of the shield depends on the degree of focusing (for example, the focal length of the lens) in the desired means, the shape of the spot of the focused laser light, and the relative positions of the transparent plastic plate, the shielding means, and the laser light detecting means. Can be set.

(Iv) laser beam detecting means, calculating means,
Image Processing Means The laser light detecting means, arithmetic means, and image processing means used in the present invention are not particularly limited, and any known means or known method can be used. The laser beam detecting means is usually a photodiode, and the calculating means and the image processing means are usually a personal computer incorporating calculation software.

Hereinafter, the silver strip inspection apparatus of the present invention will be described in more detail with reference to the drawings. FIG. 1 shows a main configuration (example) of a silver strip inspection apparatus of the present invention. In FIG. 1, reference numeral 11 denotes a laser light source, and a laser light emitted from the laser light source is condensed as a laser light spot on a surface of an object 13 via a lens 12. The laser beam spot can scan a desired area on the object 13 by integrating the laser light source and the detector 14 with a jig or by moving the object 13 two-dimensionally.

The laser beam transmitted through the object 13 reaches the detector 14 via the shielding member 15. In the detector 14, the arrived laser light generates a voltage and is digitized as a voltage signal. The shielding member 15 is arranged near the surface of the detector 14 with its center coincident with the optical axis of the focused laser beam.

Next, the voltage signal from the detector 14 is
After being amplified by the amplifier 17, the signal is converted into a digital signal by the AD converter 18. The digital signal is transmitted to the arithmetic unit 19, where it is combined with the scanning position on the surface of the device under test to create a voltage image of the scanning area.

The silver strip existing on the object 13 can be inspected as follows. The laser light transmitted through the device under test 13 passes through the shielding member 15 and passes through the detector 14.
, But no silver stripes exist on the DUT 13, the shielding material 15
Since it is manufactured to have the same size as the projected shape when it reaches the surface of, it is shielded by the shielding material 15 and does not reach the detector. However, when silver stripes exist on the surface of the DUT 13, the laser light is refracted by the silver stripes, and the traveling direction changes. Therefore, the refracted laser light reaches the surface of the detector 14 without being shielded by the shielding member 15 and generates a voltage. The voltage signal of the detector 14 is amplified by the amplifier 17 and taken into the arithmetic unit 19 as a digital signal by the AD converter 18. In the arithmetic unit 19, the digital signal is combined with the scanning position on the surface of the device under test 13 to create a voltage image of the scanning region.

FIG. 2 shows the principle of silver strip detection. At the scanning position (a) on the DUT 13, the spot of the condensed laser light is transmitted through the DUT 13, is blocked by the shielding member 15, and does not reach the detector 14.
Therefore, no voltage is generated. However, at the scanning position (b), the spot of the condensed laser light is refracted by the silver strip 16 on the surface of the DUT 13, and a part of the spot leaks to the outside of the shielding member 15. , Detector 14 generates a voltage. That is, by scanning the spot of the converged laser light on the surface of the DUT 13, the position where the silver stripe exists can be determined in the scanning region of the DUT 13.

FIG. 3 shows an example in which a voltage change on a scanning line when the converged laser light is scanned on the object 13 is recorded. Where silver stripes are present, the generated voltage can be recorded as a peak. Therefore,
By setting a predetermined threshold value for the generated voltage, a position exceeding the threshold value can be made to correspond to a position where a silver strip exists.

FIG. 4 is an example of a voltage image showing a peak voltage exceeding a threshold value in a scanning region of the device under test 13. Points on the image indicate points where the peak voltage generated by the detector 14 exceeds a predetermined threshold.

Since a silver strip is usually present in the form of a straight line having a length of several mm, the line connecting the peak voltages caused by the silver strip on the above-mentioned voltage image is calculated from the positions of both end points thereof. It can be recorded as a straight line on the image. At the same time, of the recorded straight lines, a straight line exceeding a predetermined length, that is, the number of silver strips is measured as the number of straight lines per unit area. FIG. 5 shows a straight line exceeding a predetermined length due to a silver strip on an image.

[0023]

EXAMPLES The present invention will be further described based on examples.
In addition, this invention is not limited at all by the following Examples.

EXAMPLE A transparent polystyrene plate having a diameter of 76 mm and a thickness of 1.2 mm was manufactured by injection molding a polystyrene pellet of a product collected from a polystyrene production apparatus.

With respect to the prepared transparent polystyrene plate, silver stripes on the surface were inspected using a laser beam measuring device shown in Table 1. When a straight line (silver strip) having a length of 3 mm or more on the image is a silver strip, the number of silver strips per unit area is 0.2 pieces /
cm ² . FIG. 1 shows the obtained image.

[0026]

[Table 1]

[0027]

As described above in detail and specifically, the silver strip inspection apparatus according to the present invention comprises (a) laser beam generating means, (b) condensing means, and (c) scanning means. , (D)
A silver strip generated on a transparent plastic plate can be objectively and easily inspected by comprising a shielding means, (e) a laser beam detecting means, (f) an arithmetic means, and (g) an image processing means. It has the effect of being able to.

[Brief description of the drawings]

FIG. 1 shows a main configuration of the present invention.

FIG. 2 shows the principle of silver strip detection in the present invention.

FIG. 3 shows a voltage change of a detector when scanning an object to be measured with a laser beam spot.

FIG. 4 illustrates an example in which points at which a voltage change of a detector exceeds a predetermined threshold when a laser light spot is scanned on a measurement object are plotted.

FIG. 5 illustrates an example in which a straight line recorded in a voltage image is recorded on an image based on the result of FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 laser 12 lens 13 device under test 14 detector 15 shielding material 16 silver strip 17 amplifier 18 AD converter 19 arithmetic unit

Claims (2)

[Claims] An apparatus for quantitatively and automatically inspecting a silver strip on a transparent plastic plate, wherein the inspection apparatus comprises:
(B) laser beam generating means, (B) focusing means for focusing the laser light on a transparent plastic plate, and (C) scanning means for scanning the focused laser light on the transparent plastic plate. (D) shielding means for shielding the laser light transmitted through the transparent plastic plate; (e) laser light detecting means for detecting the refracted laser light leaked from the shielding means; Calculating means for calculating the amount and position of the silver strip from the scanning position;
(G) An image processing apparatus for recording a calculation result obtained from the calculating means on an image. 2. The condensing means according to claim 1, wherein the spot shape of the laser light condensed on the transparent plastic plate has an aspect ratio (major axis: minor axis) of 5: 1 to 2: 1. The silver strip inspection device according to claim 1.