JPH02179472A - Ultrasonic wave seam detector - Google Patents

Abstract

PURPOSE:To make it possible to detect a seam part regardless of the color, the presence or absence of a picture pattern and the quality of a material to be detected by detecting the fact that the transmitting amount of ultrasonic wave at the seam part of the material to be detected is decreased in comparison with the normal part in no contact with the material to be measured. CONSTITUTION:A squared wave A from an oscillating circuit 1 is amplified 2, and a square wave B is obtained. An ultrasonic wave is emitted from an ultrasonic transmitter 3 based on the square wave B. The most of the wave is reflected from the surface of a material to be detected 4, and the remaining part is transmitted through the material. A part of it is received with an ultrasonic wave receiver 5, and the other is reflected. The transmitted amount which is received with the receiver 5 is slightly reduced at a thick seam part than at a normal part. Then, the output of the receiver 5 is detected with a preamplifier 6, a detector circuit 7 and a low-pass filter circuit 8 in a detector part. A reference value is generated in a sensitivity adjuster 10 based on a peak value which is held with a peak hold circuit 9 in a discriminating part. The values are compared in a comparator circuit 11. Whether the detected value is larger or smaller than the reference value is discriminated, and the seam part is detected.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an ultrasonic wave transmitter and a delivery device that face each other, and an object to be measured that is disposed between them without contact. The present invention relates to an ultrasonic seam detector for detecting seam positions.

[Conventional technology]

Taking a web (strip-like object) as an example of an object to be detected, the seams of the web are connected by seam tape or the like, and the seam portions are thicker than normal portions. Therefore, the joint portion can be detected by detecting the position where the seam is thicker than the normal portion.

Note that the material of the web used for -i is paper.

There are cellophane, aluminum foil, polylaminate, etc. Materials for seam tape include paper, vinyl, aluminum foil, etc. The web and the seam tape do not necessarily have to be made of the same material. By the way, seam detectors are installed in various machines such as rotary printing presses, laminators, and slitters. Among these, in offset rotary printing presses, if the web thickness increases at the seam, the plate cylinder will be damaged, so to avoid this, the plate cylinder is released at the seam. In addition, in rotary printing presses, laminators, slitter machines, etc., if seams are mixed into the final product, it will cause a quality control problem. Processing such as adding a .

Conventionally used seam detection methods include a contact method in which a mechanical contact is applied to the object to be detected and the seam is detected by the displacement of the contact, and a visible or infrared light is emitted to detect the seam from the object to be detected. There are non-contact photoelectric types that detect seams based on changes in the amount of transmitted light or reflected light, and non-contact capacitive types that detect seams by detecting changes in capacitance in areas where the thickness changes.

[Problems with conventional technology]

In the case of the contact type of the above-mentioned prior art, high mechanical precision is required for the contact portion especially when the object to be detected is thin, and when the object to be detected is soft, it becomes difficult to detect the seam. Furthermore, in the case of a photoelectric type, it cannot be used if the object to be detected has a pattern, is a transparent film, or is light-shielding. If the capacitive type is used, it cannot be used if the object to be detected is aluminum foil, etc. In addition, there may be restrictions on the color, material, etc. of the seam tape to be used.

An object of the present invention is to provide an ultrasonic seam detector that is non-contact and capable of detecting seams regardless of the color, pattern, material, etc. of the detected object.

[Means for Solving the Problems] In order to achieve the above-mentioned problems, the joints are detected by detecting a decrease in the amount of ultrasound transmitted through the joints of an object using airborne ultrasound, and the present invention consists of an ultrasonic transmitter that transmits ultrasonic waves, and an object to be detected that is installed opposite the ultrasonic transmitter and moves relative to the ultrasonic transmitter between the opposing sides. an ultrasonic receiver that receives the transmitted ultrasonic waves, and a predetermined reference value for the transmitted received waves of the normal part of the detected object and the transmitted received waves of the joint part received by the ultrasonic receiver. The present invention is characterized in that it includes a seam detection section that compares and detects seam portions. Further, the seam detection section includes a detection section that detects the output of the ultrasonic wave receiver and detects a signal corresponding to the magnitude of transmitted and received waves, and a detection section that compares the output of the detection section with a predetermined standard and detects the detected signal. It may also include a discrimination section that discriminates the magnitude of the output from the reference, and the discrimination section may include a peak hold circuit that holds the peak value of the output of the detection section, and a peak value held by the peak hold circuit. It may also include a reference value generation circuit that generates the predetermined reference, and a comparison circuit that compares the output of the reference value generation circuit and the output of the detection section, and further includes the ultrasonic transmitter and the It is preferable that the ultrasonic wave receiver and the ultrasonic wave receiver are disposed opposite to the object to be detected at an angle IIJ'I.

[For production]

The joint part of the object to be detected is thicker than the normal part. Therefore, the amount of transmitted waves transmitted through the object moving between the ultrasonic transmitter and the ultrasonic receiver placed opposite each other and received by the ultrasonic receiver is normal at the joint. decreases more than 100%. A joint can be detected by comparing this decrease with a predetermined reference value.

As a seam detection section, the detection section detects i from the output of the ultrasonic receiver.
3. Detects the signal according to the magnitude of the transient, and the discrimination section compares the output of the detection section with a predetermined reference value within the range of the output value of the detection section, and detects the signal exceeding the reference value from the object to be detected. The signal below the standard is determined as the normal part and is distinguished from the joint part of the detected object.

As a discriminator, the peak hold circuit holds the peak value of the detector for a time constant of the peak hold circuit, the reference value generation circuit generates a reference value based on the peak value held by the peak hold circuit, and the comparison circuit holds the peak value of the detector for a time constant of the peak hold circuit. The reference value is compared with the output of the wave detector to determine whether it is larger or smaller than the reference value.

In addition, by arranging the ultrasonic transmitter and the ultrasonic receiver facing each other at an angle with respect to the detected object, the reflected waves of the ultrasonic waves emitted from the ultrasonic transmitter on the detected surface can be Interference with the waves transmitted by the sonic wave transmitter can be prevented. Also, the transmitted waves that have passed through the object to be detected are reflected by the receiving surface of the ultrasonic receiver, and this reflected wave is further reflected by the object to be detected. This can prevent the ultrasonic waves from entering the ultrasonic receiver and interfering with the waves transmitted through the object to be detected.

As a result, a stable delivery output can be obtained against fluctuations in the path line of the object to be detected.

(Example) Hereinafter, an example of the present invention will be described using FIG. 1 and FIG. 2.

FIG. 1 is a block diagram showing the configuration of this embodiment.

1 is an oscillation circuit that oscillates a square wave, 2 is a power amplification circuit that amplifies the power of the output of the oscillation circuit 1, 3 is an ultrasonic transmitter that transmits ultrasonic waves using the output of the power amplification circuit 2, and 4 is an object to be detected. Object 5 is an ultrasonic receiver that receives ultrasonic waves transmitted through the object 4 to be detected. The ultrasonic transmitter 3 and the ultrasonic receiver 5 are arranged at an angle with respect to the object 4 to be detected. 6 is a preamplifier circuit that amplifies the output of the ultrasonic receiver; 7 is a detection circuit that detects a signal representing the thickness of the object to be detected 4 from the output of the preamplifier circuit 6;
8 is a low-pass filter circuit for smoothing the output of the detection circuit 7, 9 is a peak hold circuit for holding the peak value of the output of the low-pass filter circuit 8, and lO is a reference value generated from the output value of the peak hold circuit 9. 11 is a comparison circuit that compares the output of the low-pass filter circuit 8 with a reference value generated by the sensitivity adjustment circuit 10; 12 is an output circuit that outputs the output of the comparison circuit 11 to the outside.

Next, the operation will be explained with reference to FIG. The symbols on the left side of each waveform in FIG. 2 correspond to the positions A to ! in FIG. 1, and each waveform indicates the output waveform at the corresponding position.

A square wave A generated by an oscillation circuit 1 is power amplified by a power amplifier circuit 2 and applied as a square wave B to an ultrasonic wave transmitter 3.

Ultrasonic waves are emitted from the ultrasonic transmitter 3 by the square wave B, most of which is reflected on the surface of the object 4 to be detected, and the rest passes through the object 4 and is received by the ultrasonic receiver 5. Some of the waves are received by the wave front and others are reflected. The output of the ultrasonic receiver 5 is C
Shown below.

The normal portion of the detected object 4 has a constant amplitude strength, but the amplitude decreases at the joint portion. The output C of the ultrasonic receiver 5 is amplified by a preamplifier 6 and becomes an output.

Since the positive and negative values of the output are symmetrical about the reference axis, the detection circuit 7 inverts the amplitude on the negative side to the positive side, making all the signals E on the positive side. When the output E of the detection circuit 7 is smoothed through the low-pass filter circuit 8, a waveform shown in F is obtained, and a high signal is obtained at the normal portion of the detected object 4 and a low signal is obtained at the joint portion. This is because the amount of transmitted and received waves is large in the normal portion, and the amount of transmitted and received waves is small in the joint portion because it is thick.

The peak value of the signal F is held by the peak hold circuit 9 for a time corresponding to its time constant, and its waveform becomes G. The sensitivity adjuster 10 generates a reference value H from the hold value G. The comparison circuit 11 discriminates based on the reference value H whether the signal F exceeds or is less than the reference value H. In the normal part of the detected object 4, F is larger than H, and in the joint part, F is smaller than H. Therefore, as shown in waveform 1, when the normal part changes to the joint part, and when the joint part changes to the normal part Since the waveform of 1 changes, the seam can be detected.

In this way, the reference value H of the comparison circuit is the output G of the hold circuit.
The value of G changes depending on the signal value in the normal section and does not take a fixed constant value. The signal value of the normal part is always used as a reference, and when the signal value decreases compared to that, it is determined that there is a seam. By updating the reference value, that is, the peak hold value, every time the thickness of the object to be detected changes, the reference value for the normal part of the object to be detected is always determined. There is no need to manually adjust the seam judgment reference value.

Next, the effects when the ultrasonic transmitter 3 and the ultrasonic receiver 5 are arranged at an angle with respect to the object to be detected 4 will be explained. If there is no inclination and it is vertical, the ultrasonic waves transmitted from the ultrasonic transmitter 3 and the ultrasonic waves reflected from the detected object 4 will interfere, and the ultrasonic waves that have passed through the detected object 4 i3 will interfere with each other. The reflected waves from the receiving surface of the ultrasonic receiver 5 interfere with each other. When the detected object 4 is displaced in its thickness direction due to such interference, the distance to the ultrasonic transmitter 3 and ultrasonic receiver 5 changes, and the direct ultrasonic wave and reflected wave strengthen each other. They weaken each other. As a result, the output of the ultrasonic wave receiver 5 is large (varies), and stable detection cannot be performed.

Therefore, by providing an inclination, the paths of the reflected wave and the direct wave are different, as shown in FIG. 1, so such interference does not occur and stable detection is possible.

[Effects of the Invention] According to the present invention, it is possible to detect a joint portion by detecting, without contacting the object, that the amount of ultrasound transmitted through the joint portion of the object is reduced compared to the normal portion.

In addition, a seam [t] can be created regardless of the pattern or light-shielding property of the object to be detected, making it possible to detect seams in transparent films and aluminum foils.

In addition, since the seam judgment reference value corresponding to the thickness of the normal part other than the seam can be automatically set while the detected object is moving, it can be adjusted to suit each detected object depending on the thickness or material of the detected object. Another advantage is that there is no need to manually set the seam judgment reference value.

Furthermore, by arranging the ultrasonic transmitter and the ultrasonic receiver at an angle with respect to the object to be detected, seam detection can be performed stably even when the object to be detected is displaced in its thickness direction. Can be done.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention, and FIG.
The figure is a diagram showing the time chart of FIG. 1. ■---Oscillation circuit 2----Power amplifier circuit 3---
-Ultrasonic transmitter 4-m-Object to be detected 5--Ultrasonic receiver 6--Preamplifier 7--Detection circuit 8-
11-Low pass filter circuit 9---Peak hold circuit 10-m-Sensitivity adjuster 11-m-Comparison circuit 12-
--Output circuit Figure 1

Claims (4)

[Claims] (1) An ultrasonic transmitter that transmits ultrasonic waves, and a detected object that is disposed opposite to the ultrasonic transmitter and moves relative to the ultrasonic transmitter between the opposing sides. An ultrasonic receiver receives the ultrasonic waves transmitted through the object, and the ultrasonic receiver receives the waves transmitted through the normal part of the object to be detected and the waves transmitted through the joint part at a predetermined level. An ultrasonic seam detector comprising: a seam detection section that detects a seam by comparing it with a reference value. (2) The seam detection section compares the output of the detection section with a detection section that detects the output of the ultrasonic wave receiver and detects a signal according to the magnitude of the transmitted and received wave, and a predetermined reference value. 2. The ultrasonic seam detector according to claim 1, further comprising a discrimination section for discriminating whether the detected value is larger or smaller than the reference value. (3) The discrimination unit includes a peak hold circuit that holds the peak value of the output of the detection unit, a reference value generation circuit that generates the predetermined reference from the peak value held by the peak hold circuit, and the reference value. The ultrasonic seam detector according to claim 2, further comprising a comparison circuit that compares the output of the generation circuit and the output of the detection section. (4) The ultrasonic transmitter and the ultrasonic receiver are arranged to face each other at an angle with respect to the object to be detected. Ultrasonic seam detector.