JPS6042883B2 - Optical top surface inspection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a top surface inspection device suitable for inspecting the top surface inclination of an open top container made of glass, plastic, or the like.

For example, in order to seal the mouth of a glass bottle with a cap, the slope of the top surface of the bottle, that is, the top surface, must fall within a certain range. For this reason, the conventional method was to place the bottle on a rotary plate, rotate it, and inspect the tenryo slant visually or with a dial gauge. However, these methods rely on acquisition, and are difficult to implement in the mass production process. It is virtually impossible to conduct a complete inspection inside the facility. A system has already been proposed that optically detects not the top of the bottle, but the top of the bottle, where a part of the top is missing, or the top is wavy and uneven.

This device also detects the sky tilt, but it cannot distinguish this from the sky's cracks and waves. SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a top surface inspection device that can detect the top and bottom of a container by distinguishing it from other similar defects.

In order to achieve this object, the present invention projects a beam of light with different brightness at the center of the focal point and around the focal point onto the surface to be inspected at the mouth of the container, and receives the reflected light from the surface to be inspected with a light receiving element. This is converted into an electrical signal, and the electrical signal is processed by an electronic circuit to determine the presence or absence of a Tenryo slant.
Examples will be described in detail below.

FIG. 1 shows a principle diagram of the optical system of the apparatus of the present invention.

Light 3 is projected from a light projector 1 toward a top surface 2 of a container to be inspected, such as a glass bottle, and its reflected light 4 is received by a photoelectric conversion receiver 5. As shown in FIG. 2, the light 3 projected from the projector 1 is strong at the center 0;
It is a diffused light that has the characteristic of becoming gradually weaker toward the periphery.

A light projector for obtaining such diffused light is, for example, a third light projector.
As shown in the figure, the light emitted from the lamp 10 is passed through a slit 1 that is wide at the center and narrows toward the periphery.
1 through the slit plate 12, and then the condenser lens 1.
It is sufficient to adopt a configuration in which the light is focused by 3. Although not shown, the scanning of the top surface 2 by the projection light 3 can be done by moving the optical system consisting of the emitter 1 and the light receiver 5 relative to the top surface 2, or conversely by moving the top surface 2. This is done by moving the optical system relative to the optical system consisting of the projector 1 and the light receiver 5, or by simultaneously driving the optical system and the container so that there is a relative velocity difference between the optical system and the top surface 2.

FIG. 4 shows an embodiment of the electronic circuit portion of the device of the present invention. The output electrical signal of the photodetector 5 is guided to a maximum value holding circuit 21 and a minimum value holding circuit 22 via a variable amplification amplifier (not shown) and a nonlinear amplifier 20, which are provided as necessary. The nonlinear amplifier 20 converts the signal into a logarithmic characteristic in order to obtain a signal having a magnitude suitable for detecting a defect on the top surface 2, that is, a characteristic in which the degree of defect and the magnitude of the obtained signal are in a linear relationship. Maximum value holding circuit 2
The maximum value stored in 1 is led to the first input terminal of the differential amplifier 23, and the minimum value stored in the minimum value holding circuit 22 is led to the second input terminal of the differential amplifier 23 and the minimum value comparator 2.
4. minimum value. The comparator 24 outputs a ゜゜1゛ signal if the minimum value from the minimum value holding circuit 22 and the lower limit value from the lower limit value setter 25 are the lower limit value. The output of the differential amplifier 23, that is, the output fluctuation range of the amplifier 20, is compared in the tolerance width comparator 27 with the - tolerance width set by the tolerance width setting device 26. Then, if the fluctuation range>tolerable range, the allowable range comparator 27 outputs a signal. The two types of “゜1゛” signals mentioned above are both signals that indicate “defective”.
It is taken out via the OR circuit 28. The output of the OR circuit 28 is inverted via the NOT circuit 29 and is also used as a signal representing a "good" state. When the top surface 2 is scanned by the light 3 in the apparatus shown in FIG. 1, if the top surface 2 has a predetermined level or height and is flat, the output of the differential amplifier 23 is zero or extremely high. This is a small value and does not exceed the permissible width shown by the width between Af) H<5L in FIG.

Further, the lower limit value indicated by L in the figure is not exceeded. Therefore, the output signals of both comparators 24 and 27 are both ゜゜0゛ signals, and it can be detected via the NOT circuit 29 that they are "good". The optical system settings at this time are as shown in FIG. It is done as if it were reflected in the direction. On the other hand, FIG. 7 shows a case where the top surface 2 exists at a level lower than the standard top surface level 2A, and light centered at the weaker 50% intensity point is directed toward the receiver 5. Once reflected.

Figure 8, on the other hand, shows the case where the top surface 2 is located at a higher level than the standard top surface level 2A, and the light centered at the point of the stronger maximum intensity is reflected toward the receiver 5. do.
Even when the top surface 2 is inclined with respect to the standard top surface level 2A as shown in FIG. 9, the intensity of reflected light changes compared to the standard time shown in FIG. 6. Since the light receiver 5 is configured to observe a small part of the focal point in a line or spot shape, the top surface 2
If the angle of inclination is greater than a predetermined value, the amount of received light will vary because the light reflecting surface will be tilted or its height will fluctuate, and the output signal of the amplifier 20 will be approximately as shown in FIG. 5b. It will look like the one shown.

In this case, since the signal fluctuation range exceeds the allowable value and the absolute value of the signal level is below the allowable lower limit,
4 and 27 both output a "1" signal, and a "defective" is detected via the OR circuit 28. Even if only one of the comparators 24 and 27 outputs a ゜゜1゛ signal, it is detected as a "defective" signal via the OR circuit 28. Even if there is no celestial slope on the top surface 2, if the level is higher or lower than the allowable value, the level of the output signal of the amplifier 20 will fall below the lower limit L, as shown in FIG. 5c. .

Therefore, the comparator 24 outputs a "゜1゛" signal, which is output as a defective signal from the OR circuit 28. If there is a relatively small top notch or top wave on the top 2, the signal shown in FIG. Although a corresponding dent occurs in the output signal of the amplifier 20, the fluctuation width can be reduced by incorporating an integrating circuit with a large time constant into the nonlinear amplifier 20.

Therefore, the comparator 27 does not output a "1" signal. Therefore, in this case, a good signal, not a bad signal, is output from the NOT circuit 29. When diffused light of uniform intensity is used, unlike the above-mentioned present invention, it is impossible to judge whether the light is good or bad based on the amount of light, and only the presence or absence of a signal is detected. According to the present invention, it is possible to detect such a distinction.Even if there is a diagonal inclination on the top surface 2, if the inclination angle is small, as shown in FIG. As shown in e, since the signal fluctuation width does not exceed the allowable value, the comparator 27 will not output a "1" signal, and unless the minimum value of the signal level falls below the lower limit value, the comparator 24 will not output a "1" signal. does not output a 64r5 signal.

Therefore, in this case as well, no defective signal is generated. The embodiment described above is just one embodiment, and various modifications are possible.

For example, the relationship between the spread distance of the projected light 3 and the intensity of the light may not be a straight line as shown in FIG. 2, but may be a curved line that is convex upward or convex downward. Logic circuits other than those shown may also be used to perform the same function. The device of the present invention described above is a non-contact type that scans optically, and can be automatically operated using an electronic circuit. Therefore, it is possible to perform a 100% inspection of the top and bottom in the mass production process. This is what makes it possible.

The defect signal in the above device can be used as an exclusion signal to exclude defective products during the production process, as a classification signal to classify products, or even as a recording signal to be recorded on a recorder. It can also be used.

[Brief explanation of drawings]

FIG. 1 is a layout diagram showing one embodiment of the device of the present invention, FIG. 2 is a line diagram showing an example of the characteristics of the projected light in FIG.
FIG. 4 is a block diagram showing an example of the electronic circuit of the device of the present invention, and FIGS. Diagrams showing the response of the device of the present invention with respect to surfaces, FIGS. 6, 7, and 8
9 and 9 are explanatory views showing the light receiving states of the light receiver with respect to various ceiling surfaces, respectively. 1... Emitter, 2... Surface to be inspected, 5.
...Photodetector, 20...Nonlinear amplifier, 2
1... Maximum value holding circuit, 22... Minimum value holding circuit, 23... Differential amplifier, 24...
... Minimum value comparator, 25 ... Lower limit value setting device,
26... Tolerance width setter, 27... Tolerance width comparator, 28... OR circuit.

Claims (1)

[Claims] 1. A projector that projects diffused light that is strong in the center and gradually weakens toward the periphery toward the top surface of the container to be inspected, and receives the light projected from the projector and reflected on the top surface, a light receiver that outputs an electric signal of a magnitude corresponding to the intensity of the received light, and the light projector, the light receiver, and the container are relatively driven so that the projected light from the light projector scans the top surface. a driving means; a nonlinear amplifier that converts the output electrical signal of the light receiver into a signal having logarithmic characteristics;
a maximum value holding circuit that stores the maximum value of the output signal of the nonlinear amplifier; a minimum value holding circuit that stores the minimum value of the output signal of the nonlinear amplifier; and the maximum value stored in the maximum value holding circuit and the minimum value a differential circuit that outputs the difference between the minimum value and the minimum value stored in the value holding circuit; a first comparator that outputs a signal indicating a defect when the output of the differential circuit exceeds a predetermined value; and a second comparator that outputs a signal indicating a defect when the minimum value stored in the value holding circuit is less than a predetermined lower limit value.