JPS6355653B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flaw inspection device for optically helical scanning a cylindrical object such as a drug capsule to detect the presence or absence of flaws.

FIG. 1a is a perspective view of a conventional flaw inspection device in normal operation. In the figure, it is assumed that a cylindrical object 4, which is an object to be inspected, is being sent in the direction of arrow A while being rotationally driven by a rotating roller 5 rotating in the direction of arrow B. On the other hand, the cylindrical object 4 is irradiated with light from the illumination devices 2 and 3,
A reflected wave from a certain point on the cylindrical object 4 is input to the photoelectric sensor 1, where it is converted into an electrical signal. That is, it can be said that the output signal obtained from the photoelectric sensor 1 is a signal obtained as a result of helical scanning around the cylindrical object 4.

The waveform of the output signal obtained from the photoelectric sensor 1 in this way is such that, if there is a flaw P such as a pinhole around the cylindrical object 4, the amount of light reflected from that part is the amount of light reflected from other normal parts. Since it is very small compared to , it becomes as shown in FIG. 1b. That is, the change point P' in FIG. 1b shows the output change caused by the flaw P on the cylindrical object 4.
Therefore, by differentiating the output signal from the photoelectric sensor 1, the output waveform shown in FIG. , such a signal change
Since P'' is not detected, the cylindrical object is determined to be a good product with no scratches.

However, in the conventional flaw inspection apparatus, when the rotating roller 5 that is supposed to drive the cylindrical object does not rotate due to a failure, or because the cylindrical object 4 does not rotate because of an irregular shape, as shown in FIG. Even if the cylindrical object 4 passes in the direction of arrow A, this does not mean that the entire area around the cylindrical object has been inspected by helical scanning.

However, the output signal of the photoelectric sensor 1 has a flat waveform with no abnormality as shown in Figure 2b, and its differential output also does not include any signal changes as shown in Figure 2c. Conventional flaw inspection devices have the risk of determining that the cylindrical object is a good product even though the entire surface of the object has not been inspected.

This invention was made in order to eliminate the drawbacks of the conventional flaw inspection apparatus as described above, and an object of this invention is to detect an object to be inspected even though the rotating roller is not rotating. To provide a flaw inspection device that does not quickly judge cylindrical objects as non-defective items.

The main points of the configuration of the present invention are that, in addition to a circuit for detecting the presence or absence of flaws on the object to be inspected, a circuit for detecting the presence or absence of rotation of the object to be inspected, and a judgment as to whether the object to be inspected is good or bad are made based on the detection results of both circuits. The point is that it is equipped with a circuit.

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 3 is a block diagram showing one embodiment of the present invention. In the figure, 6 is a signal amplification amplifier;
7 is a flaw detection circuit, 8 is a rotation detection circuit, 9 is a comprehensive judgment circuit, 10 is a defective product ejecting section, and others,
The same reference numerals as in FIGS. 1 and 2 refer to the same parts.

In FIG. 3, the cylindrical object 4 which is the object to be inspected
advances while being rotated by rotating rollers 5. The cylindrical object 4 is illuminated by the illumination devices 2 and 3, and the photoelectric sensor 1 converts the change in brightness of the illuminated area into an electrical signal. The output of this photoelectric sensor 1 is amplified by a signal amplification amplifier 6 and inputted to a flaw detection circuit 7 and a rotation detection circuit 8.
The flaw detection circuit 7 detects the presence or absence of flaws and outputs the result to the general judgment circuit 9, and the rotation detection circuit 8 detects the presence or absence of rotation of the cylindrical object 4 and outputs the result to the general judgment circuit 9. The comprehensive judgment circuit 9 determines that the output of the scratch detection circuit 7 is valid only when the output from the rotation detection circuit 8 is "rotation present", and rejects the defective product if it is "rotation present" and "scratches present". A command is issued to section 10 to discharge the cylindrical object as a defective product.

FIG. 4 is a circuit diagram showing a configuration example of the flaw detection circuit 7;
FIG. 5 is a timing chart of various signals in FIG. 4.

In FIG. 4, 11 is a differentiator, 12 and 13 are comparators, 14 is a timer such as a monostable multivibrator, 15 is a counter, and 16 is a timer such as a monostable multivibrator.
is a digital comparator.

The operation will be explained with reference to FIGS. 4 and 5. The output signal A sent from the photoelectric sensor via the amplification amplifier is input to the differentiator 11 and differentiated. If the output signal A contains a flaw signal as seen in FIG. 5, its differential output B will have a waveform as shown in FIG. This differential output B is set to a certain reference voltage in the comparator 13.
When compared with TH ₁ and binarized, a rising signal C as shown in FIG. 5 is obtained via an inverter I. On the other hand, when the differential output B is compared with another reference voltage TH ₂ in the comparator 12 and binarized, a falling signal D as shown in FIG. 5 is obtained. Furthermore, when the timer 14, which is composed of, for example, a monostable multivibrator, is operated at the falling edge of the falling signal D, a timer output H as shown in FIG. 5 is obtained. When the AND gate A outputs the logical product of the timer output E and the rising signal C, this becomes the flaw detection signal as shown in FIG.
5 is input. In other words, if a cylindrical object has a scratch such as a pinhole, the amount of light reflected from that spot will decrease, causing a change in the output of the photoelectric sensor, and this change is detected by the scratch detection circuit. .

This flaw detection signal is counted by a counter 15, and the count result is compared with a certain reference value by a digital comparator 16. If it exceeds the reference value, it is determined that there is a flaw, and if it does not exceed it, it is determined that there is no flaw. and output the result.

FIG. 6 is a circuit diagram showing an example of the configuration of the rotation detection circuit 8, and FIG. 7 is a timing chart of signals of various parts in FIG.

In FIG. 6, 17 is a differentiator, 18 is a comparator, 19 is a timer such as a monostable multivibrator, 20 is a counter, and 21 is a digital comparator.

The operation will be explained with reference to FIGS. 6 and 7. The output signal A sent from the photoelectric sensor via the amplification amplifier is input to the differentiator 17 and differentiated. As seen in FIG. 7, this differential output B includes level fluctuations depending on the rotational frequency of the cylindrical object due to fluctuations due to the rotation of the cylindrical object. When this differential output B is compared with a certain reference value _VTH in a comparator 18 and converted into a binary value, a comparator output C as shown in FIG. 7 is obtained via an inverter I. This comparator output C becomes a pulse train signal having a repetition frequency that corresponds to the rotational frequency of the cylindrical body. At the falling edge of each pulse of the comparator output,
For example, when a timer 19 consisting of a mono-multivibrator is operated, a timer output D as shown in FIG. 7 is obtained. The logical AND output of the timer output D and the comparator output C is output from the AND gate A, and the input E to the counter 20 is obtained as shown in FIG.
The counter 20 counts this input signal, and the count result is compared with a certain reference value in the digital comparator 21. If the reference value is exceeded, it is determined that the cylindrical object is rotating, and if it is not, it is determined that there is no rotation.
The judgment result is output.

As explained above, in the flaw inspection apparatus according to the present invention, flaw detection and rotation detection of the cylindrical body are performed, and the inspected object is determined to be non-defective only when no flaw is detected but rotation is detected. Others are determined to be defective and are discharged to the defective side by the defective article discharging section 10.

According to this invention, since the flaw detection circuit is combined with the rotation detection circuit, a cylindrical object that does not rotate normally can be determined to be defective. In other words, even if the cylindrical object is crushed and does not rotate properly, the rotation detection circuit cannot detect the rotation, so it can be determined that the object is defective.

The explanation so far has been about the case where a cylindrical object made of an opaque material is inspected using a reflected light sensor, but a cylindrical object made of a transparent material can also be inspected in the same way. In the case of a transparent cylindrical object, the structure of the flaw detection circuit is slightly different: a rising signal activates a timer to create a gate signal circle, and a logical product with a falling signal generates a flaw detection signal. In other words, if a transparent cylindrical object has a hole, light will be reflected only at the edge of the hole and this signal will be captured. Inspection performance of transmitted light sensors can also be improved using a similar concept.

[Brief explanation of the drawing]

Fig. 1a is a perspective view showing a conventional flaw inspection device operating normally, Fig. 1b is an output waveform diagram of the photoelectric sensor in Fig. 1a, Fig. 1c is a differential waveform diagram of the same output waveform, and Fig. 1c is a differential waveform diagram of the same output waveform. Figure a is a perspective view showing a conventional flaw inspection device when the rotating roller is stopped, Figure 2b is an output waveform diagram of the photoelectric sensor in Figure 2a, Figure 2c is a differential waveform diagram of the same output waveform, FIG. 3 is a block diagram showing an embodiment of the present invention, FIG. 4 is a circuit diagram showing an example of the configuration of the flaw detection circuit 7 in FIG. 3, and FIG. 5 is a timing chart of various signals in FIG. 4.
FIG. 6 is a circuit diagram showing an example of the configuration of the rotation detection circuit 8 in FIG. 3, and FIG. 7 is a timing chart of signals of various parts in FIG. Description of symbols 1...Photoelectric sensor, 2, 3...Lighting device, 4...Cylindrical object, 5...Rotating roller, 6...
...Signal amplification amplifier, 7...Flaw detection circuit, 8...
Rotation detection circuit, 9... Comprehensive judgment circuit, 10... Defective product discharge section, 11, 17... Differentiator, 12, 1
3, 18... Comparator, 14, 19... Timer,
15, 20... Counter, 16, 21... Digital comparator.

Claims (1)

[Claims] 1. Helical scanning of the surface of a cylindrical object being sent while rotating by irradiating the object with light;
A flaw inspection device that determines the presence or absence of flaws on the surface of the cylindrical object by converting the reflected light into an electric signal using a photoelectric sensor and outputting it, and processing the output waveform, the flaw inspection device comprising: a differential sensor that differentiates the sensor output; a first detection circuit that detects the presence or absence of a flaw from the timing of successive generation of first and second outputs obtained by slicing the differential output using first and second thresholds;
A second detection circuit detects the presence or absence of rotation of the cylindrical object from the periodicity of the pulse train in the third output obtained by slicing the differential output by a third threshold, and the first detection circuit detects scratches. 1. A determination circuit that determines a cylindrical object to be a good product only when a second detection circuit detects the presence of rotation without detecting rotation.