JP5240895B2 - Ultrasonic edge position detector - Google Patents

Description

  The present invention relates to an ultrasonic edge position detection device.

  As an apparatus for detecting an edge position (end position) of an object to be detected, an ultrasonic edge position detection apparatus is known.

  As a prior art document disclosing an ultrasonic edge position detection device, for example, there is Patent Document 1.

  FIG. 6 is a perspective view showing the configuration of the oscillating unit and the receiving unit of the ultrasonic edge position detecting device of Patent Document 1. In FIG.

As shown in FIG. 6, the oscillating unit and the receiving unit of the ultrasonic edge position detection apparatus of Patent Document 1 are configured by arranging the cores 1002 in a staggered manner using the matching layer 1001 as a common base.
US Pat. No. 5,834,877

  The ultrasonic auto-wide detector of Patent Document 1 requires the matching layer 1001 and can only handle ultrasonic waves having a resonance frequency.

  The present invention has been made to solve the above-described problems, and provides an ultrasonic edge position detection device that does not require a matching layer in an element and can determine an ultrasonic frequency freely. The purpose is to do.

  In order to solve the above problems, an ultrasonic edge position detection device according to the present invention includes an oscillating unit that oscillates ultrasonic waves, a receiving unit that receives ultrasonic waves oscillated from the oscillating unit, the oscillating unit, and the receiving unit. In the ultrasonic edge position detection device, comprising: a detection processing unit that performs a process of detecting an edge position of an object to be detected that is inserted between the detection unit and the detection unit based on a reception signal from the reception unit. The oscillating element for oscillating ultrasonic waves includes a plurality of enclosures in which a PVDF film is incorporated in a waveform, and the receiving unit includes a plurality of enclosures in which PVDF films are incorporated in a waveform as receiving elements for receiving ultrasonic waves. It is characterized by.

  According to the present invention, each of the oscillating unit and the receiving unit includes an enclosure in which a PVDF film is incorporated in a waveform as an element that oscillates and receives an ultrasonic wave. Can be determined freely.

  Embodiments according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a front view illustrating a configuration of an ultrasonic edge position detection device 100 according to the embodiment, and FIG. 2 is a perspective view illustrating an appearance of the ultrasonic edge position detection device 100.

  The ultrasonic type edge position detection apparatus 100 according to the present embodiment detects the position of the end (edge) of the detected object 10, and as shown in FIGS. 1 and 2, the upper part located on the upper side. It consists of 100A, a lower part 100B located on the lower side, and an intermediate part 100C that connects these parts 100A and 100B to each other, and has an overall U-shaped cross section.

  A space between the upper portion 100A and the lower portion 100B constitutes an insertion region 100D into which the detection object 10 is inserted.

  For example, the lower part 100B is provided with an oscillating unit 1 that oscillates ultrasonic waves, and the upper part 100A includes a receiving unit 2 that receives ultrasonic waves oscillated from the oscillating unit 1 and a CPU. And a detection processing unit 3 that performs detection processing of the edge position of the detected object based on the reception result of 2.

  As shown in FIG. 1, a plurality of enclosures 4 are arranged in a row in each of the oscillation unit 1 and the reception unit 2.

  An enclosure 4 (oscillation element) that is disposed on the oscillation unit 1 side and oscillates ultrasonic waves, and an enclosure 4 (reception element) that is disposed on the reception unit 2 side and receives ultrasonic waves from the oscillation element are disposed opposite to each other. Has been.

  FIG. 3 is a perspective view showing the appearance of the enclosure 4.

  As shown in FIG. 3, the enclosure 4 has a rectangular parallelepiped outer shape, and includes a first portion 4A constituting substantially the upper half thereof, a second portion 4B constituting substantially the lower half thereof, and the first and first portions. A PVDF (polyvinylidene fluoride) film 5 incorporated between the two portions 4A and 4B, and first and second terminals 6 and 7 disposed on the front side of the first portion 4A are provided.

  The PVDF film 5 is formed into a corrugated shape by being sandwiched between a corrugated portion formed on the lower surface of the first portion 4A and a corrugated portion formed on the upper surface of the second portion 4B.

  The first part 4 </ b> A and the second part 4 </ b> B are connected to each other by a fastening member 8.

  Further, the PVDF film 5 is subjected to electrode treatment on the front and back, and the front side electrode is electrically connected to the terminal 6 and the back side electrode is electrically connected to the terminal 7.

  The feature of PVDF is that the air medium can be easily and efficiently vibrated directly from the element due to the low acoustic impedance and density.

  Normally, a ceramic piezoelectric element is known as an ultrasonic element. However, in order to vibrate an air medium, a matching layer or the like is required for matching acoustic impedance.

  On the other hand, when the PVDF film 5 is used, the matching layer is unnecessary for the above reason.

  Another major feature of PVDF is that the ultrasonic frequency can be determined freely. In the case of a ceramic piezoelectric element, only the resonance frequency can be handled, but if the radius of curvature of the waveform woven into the enclosure 4 is set to a predetermined value, the desired ultrasonic frequency can be handled.

  In addition, since the size of the element can be freely set, the field of view per element can be made considerably wider than that of the ceramic piezoelectric element, and as a result, a wide detection range can be obtained particularly in the detector specifications. When required, it is a great cost advantage.

  Furthermore, since the PVDF film 5 is not linear between oscillation and reception, there is no unnecessary reflection, and the processing of the received signal (reception signal) is easy. For this reason, there is also an advantage that it is not necessary to wait for the attenuation of the reflected signal reciprocating between the transmission side and the reception side.

  FIG. 4 is a schematic diagram for explaining the arrangement of elements (enclosure 4).

  In FIG. 4, the reference numerals of the enclosures 4 are omitted for the sake of simplicity, and for convenience of explanation, numbers (1, 2,..., N−2, n−1, n, n + 1) are assigned to the enclosures 4. Etc.).

  As shown in FIGS. 4 and 2, the basic structure is that a plurality of enclosures 4 as transmitting elements are arranged in the oscillator 1 so as to form a line in a direction perpendicular to the longitudinal direction. Similarly, in the receiving unit 2, a plurality of enclosures 4 as receiving elements are arranged side by side in a row in the same direction as the enclosure 4 on the transmission side. The positions of the transmission-type enclosure 4 and the reception-type enclosure 4 are shifted by a half pitch in the column direction (half the length in the direction orthogonal to the longitudinal direction of the enclosure 4). The two enclosures 4 on the transmission side are arranged so as to face each enclosure 4. The purpose of this arrangement is to widen the detection field of view for each receiving element.

  In FIG. 4, among the elements (reception elements) arranged in the reception unit 2, the reception element for detecting the edge position of the detected object is n, and the element on the oscillation unit 1 side corresponding to the reception element n ( The oscillation elements are n and n + 1 (solid hatched portion).

  Here, the fully open reference element, the fully closed reference element, and the auxiliary vibration element / element switching determination element will be described.

<Fully open reference element>
The fully open reference element is arranged at a position where the object to be detected is not shielded no matter where in the detection visual field. The fully open reference element is used as a reference for each element for detection, and is used for compensation of the fully closed and fully open scales together with the fully closed reference element described later. In FIG. 4, the reception fully open reference element is 1, and the oscillation fully open reference element is 1 and 2.

  In general, ultrasonic waves are easily influenced by the surrounding environment (temperature, humidity, air flow), and the influence is reduced by using signals of these compensating elements.

<Fully closed reference element>
The full-closed reference element is used for always making the full-closed and full-open scales by the object to be detected correct and for reducing the influence from the change in the surrounding environment.

  In FIG. 4, the fully closed reference elements for reception are n + 1, and the fully closed reference elements for oscillation are n + 1 and n + 2.

<Auxiliary vibration element and element switching judgment element>
Depending on the edge position of the object to be detected, it is necessary to switch the effective element appropriately. Immediately after switching, the oscillation element adjacent to the edge detection element is driven in advance in order to make the received signal accurate. Keep it.

  In FIG. 4, the oscillation elements n-1 and n + 2 are auxiliary vibration elements / element switching determination elements (n and n + 1 are already driven).

  At the same time, appropriate element switching is performed by measuring the detection signals (reception signals) of the receiving elements n−1 and n + 1 for determination of effective element switching.

  Next, driving means for the oscillation element will be described.

  In order to generate ultrasonic waves of a predetermined frequency from the PVDF film 5 that is an oscillation element, an AC signal having an amplitude around 200 Vp-p (pp is a meaning of peak to peak) between the front and back electrodes of the PVDF film 5. It is necessary to drive with.

  Since the ultrasonic wave uses air as a medium, a sine wave having a frequency of about 40 kHz to 400 kHz is appropriate. Further, since it is a relatively high voltage of 200 Vp-p, a class E amplifier is suitable as a drive circuit.

  Here, the class E amplifier is a high-efficiency zero volt switching circuit using an LC resonance circuit, and can generate a high-voltage sine wave with a very simple circuit.

  Next, a received signal processing method by the detection processing unit 3 will be described.

  FIG. 5 is a diagram for explaining the detection operation, and shows the time-dependent change of the oscillation / driving signal from the oscillation-side enclosure 4 and the reception signal by the reception-side enclosure 4.

  A burst mode is used as the ultrasonic wave generation form.

  The received signal is subjected to detection and LPF (low-pass filter) processing, and the rising slope of the signal is measured and evaluated as shown in FIG. A method for measuring and evaluating the rising slope of the signal in this way is detailed in Japanese Patent Application Laid-Open No. 2003-97933 by the present applicant.

  When the detected amount is 100% (fully closed state), the inclination is zero.

  According to the first embodiment as described above, the end (edge) position of the object to be detected can be detected within a wide field of view, and in particular, the edge position of a film or nonwoven fabric that is difficult to detect optically. Can be detected stably.

  Moreover, since the enclosure 4 in which the PVDF film 5 is incorporated in the waveform is used as the element, the element does not require a matching layer, and the ultrasonic frequency can be freely determined.

It is a front view which shows the structure of the ultrasonic type edge position detection apparatus which concerns on embodiment. It is a perspective view which shows the external appearance of an ultrasonic type edge position detection apparatus. It is a perspective view which shows the external appearance of an enclosure. It is a schematic diagram which shows the arrangement | sequence of an enclosure. It is a figure for demonstrating a detection operation. It is a perspective view which shows the conventional element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Ultrasonic edge position detection apparatus 1 Oscillation part 2 Reception part 3 Detection processing part 4 Enclosure (element)
5 PVDF film

Claims (3)

An oscillator that oscillates ultrasonic waves;
A receiving unit for receiving ultrasonic waves oscillated from the oscillating unit;
A detection processing unit for performing processing for detecting an edge position of an object to be detected inserted between the oscillation unit and the reception unit based on a reception signal by the reception unit;
In an ultrasonic edge position detection device comprising:
The oscillating unit includes a plurality of enclosures in which a PVDF film is incorporated in a waveform as an oscillating element that oscillates an ultrasonic wave,
The ultrasonic wave edge position detecting device, wherein the receiving unit includes a plurality of enclosures each having a PVDF film incorporated in a waveform as a receiving element for receiving ultrasonic waves.   The detection processing unit receives a reception signal from a receiving element that detects an edge position of the detection object, a reception signal from a reception element having a detection rate of 0%, and a detection rate of the detection object of 100%. The ultrasonic edge position detection apparatus according to claim 1, wherein correction is performed based on a reception signal from the element. In the oscillating unit, a plurality of transmitting elements are arranged side by side in a row,
In the receiving unit, a plurality of receiving elements are arranged side by side in a row in the same direction as the transmitting elements,
3. The two oscillating elements are opposed to one receiving element by arranging the receiving element and the transmitting element at a position shifted by a half pitch in the column direction. The ultrasonic type edge position detection apparatus described in 1.