JP5939516B2 - Method and apparatus for tuning a pitched membrane percussion instrument - Google Patents

Description

  The present invention relates to a tuning method and apparatus for a pitched percussion instrument, and more particularly to a tuning method and apparatus for timpani (also referred to as a kettle drum).

  As a tuner that can easily tune (tune) a percussive instrument, the sound collected from the microphone is converted into an electrical signal, amplified to an electrical signal of a desired level by an amplifier, and the sound collected by the microphone from the output signal of the amplifier. There is a tuning device that extracts the basic period of the sound and tunes it with a preset reference sound. Patent Document 1 discloses a timpani pitch adjusting device that detects a head hitting sound with an external microphone, determines a pitch by measuring a frequency with a tuning meter, and automatically sets a head tension based on the determination signal. It is disclosed.

  As a tuner that easily tunes (tunes) wind instruments, clip-type ones using contact microphones and piezo microphones are sold. A cordless type has also been proposed.For example, in Patent Document 2, a clip for mounting on a musical instrument, a vibration sensor provided on the clip, and the clip are connected to each other via a connecting portion. Disclosed is a tuning device comprising: an electronic circuit that determines a sound state of the musical instrument by processing a signal obtained from the vibration sensor; and a display unit that displays a determination result of the electronic circuit. Yes.

Japanese Patent No. 4109302 JP 2003-255932 A

  In the configuration in which sound is collected by a microphone as in Patent Document 1, all surrounding sounds are detected. Therefore, in an environment where there is sound other than the tuning target sound, such as when performing with a large number of people. There was a problem that accurate tuning was difficult. In particular, it was virtually impossible to accurately change the pitch using a tuning gauge during performance.

  Further, a contact microphone / piezo microphone and a wind instrument tuner as disclosed in Patent Document 2 cannot be used for tuning a percussion instrument (percussion instrument with leather or plastic film).

  An object of the present invention is to provide a tuning method and apparatus for a pitched percussion instrument that can solve the above-described problems.

  When tuning a pitched percussion instrument with a conventional contact microphone / piezo microphone, the frequency of the percussion sound could not be measured accurately. The inventor considered that this is caused by using a ceramic-based piezoelectric (piezo) sensor in a conventional contact microphone / piezo microphone. That is, the inventor has shown in FIG. 2 that the ceramic piezoelectric sensor is made of a hard material and not a flexible structure as shown in FIG. The knowledge that the vibration of the timpani head shown in the figure cannot be converted into an electrical signal was obtained. Therefore, the inventor thought that it would be possible to accurately measure the frequency of the hitting sound with a flexible sheet-like piezoelectric sensor, and created the present invention after intensive studies.

That is, the first invention is a flexible sheet-like piezoelectric sensor that converts vibration of a membrane percussion instrument into an electrical signal, an arm to which the piezoelectric sensor is fixed and adjustable in length, A fixing unit that is detachably fixed to the percussion instrument, a support unit that connects the arm and the fixing unit, and an output circuit that amplifies and outputs an electrical signal obtained from the piezoelectric sensor. A tuning device for a pitched membrane percussion instrument, wherein the piezoelectric sensor comprises a piezoelectric film sensor having a curved portion and transmitting vibrations of the membrane on a lower surface, and the tuning device is A tuning device for a membrane percussion instrument having a pitch, which is detachably fixed to the membrane percussion instrument.
According to a second invention, in the first invention, further includes a processing unit that processes an electrical signal obtained from the piezoelectric sensor to determine a pitch name, and a display unit that displays a determination result by the processing unit. It is characterized by that.

The third invention is the invention of the first or 2, wherein the piezoelectric sensor, characterized in that it consists of a U-shaped piezoelectric film sensor.
According to a fourth invention, in any one of the first to third inventions, the piezoelectric sensor includes a polyvinylidene fluoride (PVDF) film.
A fifth invention is characterized in that, in any one of the first to fourth inventions, the length of the support portion is adjustable.
According to a sixth invention, in any one of the first to fifth inventions, the membrane percussion instrument is a timpani.

  According to the present invention, it is possible to easily and accurately perform tuning of a pitched percussion instrument with a piezoelectric sensor.

It is a side view which shows the structure of the conventional ceramic type piezoelectric sensor. It is a top view which shows the vibration image of the head of a timpani. 4 is a photograph showing a measurement mode using the tuning device according to Example 1. FIG. 3 is a graph of voltage change when measured by a tuning device according to Example 1; It is a frequency spectrum of FIG. It is a graph of the voltage change at the time of measuring with the tuning apparatus which concerns on Example 2. FIG. It is a frequency spectrum of FIG. FIG. 6 is a top view and a side view showing a structure of a piezoelectric film sensor according to Example 3. It is a figure explaining the structure of a piezoelectric film sensor, and how to change a resonant frequency. 6 is a graph of voltage change when measured by a piezoelectric film sensor according to Example 3. It is a frequency spectrum of FIG. 6 is a graph of voltage change when measured by a piezoelectric film sensor according to Example 4. It is a frequency spectrum of FIG. 6 is a side view showing the structure of a piezoelectric film sensor according to Example 4. FIG. It is a frequency spectrum at the time of measuring with the piezoelectric film sensor which concerns on Example 4. FIG. It is a frequency spectrum at the time of measuring in each position of i-iv of FIG.

  According to the present invention, a flexible sheet-like piezoelectric sensor is disposed on a membrane percussion instrument membrane to convert the vibration of the membrane into an electrical signal, and the pitch of the pitch is determined by an electronic circuit that processes the electrical signal. The present invention relates to a tuning method and apparatus for a percussion instrument.

  Since the piezoelectric sensor needs to follow the vibration of the head (film), a flexible sheet-shaped piezoelectric sensor, preferably an elastic film-shaped sensor is used. Examples of piezoelectric films include piezoelectric ceramics or piezoelectric ceramic thin films made of PVDF (Polyvinylidene fluoride film), barium titanate, lead zirconate titanate (PZT), etc., but they are lightweight, flexible and workable. A good material is PVDF. PVDF has a feature that it has a very wide response band and is difficult to have a specific resonance frequency. Although some piezoelectric elements are made of non-flexible materials such as ceramics, they cannot be used in the present invention because they cannot follow the vibration of the head (film) as described above.

An adhesive layer is formed on the lower surface side of the piezoelectric sensor as needed, or can be attached to a timpani head using a double-sided adhesive sheet, an adhesive tape, or the like. At this time, the piezoelectric sensor may be brought into pressure contact with the head by a surface pressing at a certain area or a plurality of points from the upper surface side of the piezoelectric sensor.
As another embodiment, use of a cantilever type piezoelectric film sensor is disclosed. The piezoelectric film sensor includes a substrate disposed on the membrane of the percussion instrument, a pin provided perpendicular to the substrate, a plate-like detection element attached to the pin so as to be substantially horizontal to the substrate, and a detection element. The sheet-shaped piezoelectric sensor (piezoelectric film) is disposed, and a weight is provided so as to be attached to and detached from the detection element.
The number of piezoelectric sensors may be singular or plural.

  The piezoelectric sensor is preferably protected against noise by shielding with a conductive cloth tape or the like. Conductive cloth tape can be a general one used for shielding electromagnetic waves and static electricity of electronic equipment, shielding of signal cables and connectors, and the adhesive surface is also conductive and conductive even when bonded. A shielding effect can be obtained.

A signal from the piezoelectric sensor is amplified to an electric signal of a desired level by an amplifier circuit as necessary, and is input to a commercially available tuning meter (tuner). The tuning meter analyzes and extracts the basic period of the input sound, compares the extracted basic period and the basic sound period to determine the pitch of the input sound, and detects the pitch error in the determined pitch. Is done. The pitch and pitch error of the input sound are displayed on the tuning meter display. Thus, the piezoelectric sensor according to the present invention can be tuned using a commercially available tuning meter.
There is a pitch error in the processing means for discriminating the pitch name based on the discrimination reference information stored in the storage means and the display means such as a liquid crystal display from the above-described flexible sheet-like piezoelectric sensor (or amplifier circuit). A tuning device including a display unit for displaying on a scale or the like is also included in the scope of the present invention.

  Timpani is known as a percussion instrument with a pitch. Timpani can change the pitch by adjusting the tension of the head, and can accurately produce the sound of Doremi. One timpani has, for example, a sound range from do to ra (flat), and 4 to 5 timpani are usually used side by side during performance.

  Timpani plays by putting a head (film) on a round pan-shaped kettle made of copper, FRP, aluminum, etc. and hitting it with a bee (mallet). By adjusting the tension of the head, the pitch can be changed and the Doremi sound can be produced accurately. The head tension can be adjusted by hand tightening the tuning bolts one by one, the handle type by adjusting all the tuning bolts at once by turning the handle, and the head tension by stepping on the pedal. There is a pedal type to change. The tuning bolt is connected to a tension rod provided radially from the metal fitting in the center of the head, and the tension of the head is adjusted by the tension rod.

  Timpani makes a sound by hitting the vicinity of the edge of the head with a bee, not the center of the head. The entire head undulates with a straight line passing through the center from side to side, and the edge hits the belly of the vibration. FIG. 2 is a top view showing a vibration image of the head when hitting the vicinity of the edge. In FIG. 2, the filled portion is a bulging portion, and the unfilled portion is a depressed portion, and the states (A) and (B) are repeated, and the entire head emits sound while undulating. It is said that a membrane vibration of the correct integer multiple of discipline can be obtained by air confined in a round kettle.

  Hereinafter, details of the present invention will be described with reference to examples, but the present invention is not limited to the examples.

Example 1 relates to a timpani tuning device using a piezoelectric film sensor.
In Example 1, a piezoelectric film was stuck on the center of a timpani head that was tuned in advance, and an experiment was conducted to determine whether the pitch name could be correctly identified (see FIG. 3). In the tuning device of Example 1, a signal from a piezoelectric film is amplified by a first amplifier (self-made charge amplifier) and a second amplifier (manufactured by Shikoku Keiki Kogyo Co., Ltd.) and a data logger (OMR ZR-MDR10). ) And its dedicated PC software.
The amplifier has a two-stage configuration, the first stage (charge amplifier) is an amplifier that converts the charge induced in the piezoelectric film into a voltage, and the second stage (voltage adjustment amplifier) is an output-side measuring instrument, etc. This is an amplifier that converts the voltage according to the input voltage. If the amplification level is changed in the first stage (charge amplifier), the input resistance may change. Therefore, the charge induced in the piezoelectric film is changed to voltage without changing the input resistance with the first stage (charge amplifier) constant. When the output voltage is small, it is amplified by the second stage (voltage adjustment amplifier).
The tuning device of Example 1 amplifies a signal from a piezoelectric film with a first amplifier (charge amplifier) and a second amplifier (voltage adjustment amplifier) manufactured by Shikoku Keiki Kogyo Co., Ltd., and a data logger (ZR manufactured by OMRON). -MDR10) and its dedicated PC software.

  In the vicinity of the power supply frequency of 60 Hz (50 Hz in eastern Japan) and 180 Hz (150 Hz in eastern Japan), which is the third harmonic, noise may be observed depending on the measurement conditions, so a notch filter is inserted.

  In Example 1, a piezoelectric film (FDT series) manufactured by Tokyo Sensor was used. In this product, this piezoelectric film is constructed by extending a silver ink screen printing electrode as a flexible circuit integrated with a sensor unit and attaching a connector. The specification of the piezoelectric film used in Example 1 is shown below.

Model number: FDT1-052K
Sheet size: 16mm x 235mm
Electrode size: 12mm x 30mm
Overall thickness: 85μm
Film thickness: 52 μm
Capacitance: 0.74nF

  FIG. 4 is obtained by amplifying the signal from the piezoelectric film when the sound of A (220 Hz) is struck by a factor of 1000 with the first amplifier and by a factor of 11.3 with the second amplifier. It is a graph of a voltage change. FIG. 5 is a frequency spectrum obtained by Fourier transform of FIG. 4, and a peak could be observed at 222.17 Hz.

  Subsequently, a connection experiment with a commercially available tuner (Yamaha TDM-70) was performed. When the piezoelectric film signal amplified 1000 times with the first amplifier was input to the tuner with the tuning frequency set to 440 Hz, the cent scale needle showed the center 0 and the sound The green lamp indicating that the

  From the above results, it was possible to confirm that the sound of A (220 Hz) could be correctly identified by the tuning device of Example 1.

  Using the same tuning device as in Example 1, a piezoelectric film was attached to the approximate center of the timpani head, and an experiment was conducted to determine whether the pitch name could be correctly identified. In the second embodiment, the timpani pedal is moved from the first embodiment, and the tuning is not performed. In addition, although the second embodiment is hit with the same strength as the first embodiment, it is not completely the same strength because it is manual.

  FIG. 6 is obtained by amplifying the signal from the piezoelectric film when the sound of A (220 Hz) is struck by three times with the first amplifier and 11.3 times with the second amplifier. It is a graph of a voltage change. FIG. 7 is a frequency spectrum obtained by Fourier transform of FIG. From FIG. 7, a peak could be observed at 221.56 Hz.

  Example 3 relates to a timpani tuning device using a cantilever type piezoelectric film sensor. In the third embodiment, an output about 10 times that of the first embodiment can be obtained, so that a simple configuration without using an amplifier can be achieved. That is, according to the piezoelectric film sensor of Example 3, it is possible to perform tuning by directly connecting the piezoelectric film sensor to a commercially available tuner (Yamaha TDM-70).

  FIG. 8 is a top view and a side view of the cantilever type piezoelectric film sensor according to the third embodiment. In Example 1, MiniSense 100 manufactured by Tokyo Sensor Co., Ltd. was used. This product is a low-cost cantilever type vibration sensor, and includes a weight 13 that exhibits high sensitivity at low frequencies. The pins 12 are designed to be easily attached and can be soldered to a printed circuit board (PCB) or the like. The active sensor portion is shielded and is less susceptible to RFI / EMI noise. The piezoelectric film 11 is PVDF, and the weight of the weight to be detected can be changed so that different frequency responses and sensitivities can be selected. When an inertial force is applied to the end of a horizontally mounted beam, the beam is bent due to acceleration in the vertical plane, and the piezoelectric device responds by distorting the beam, which is detected as a charge or voltage output from the sensor electrode. Is done. The MiniSense 100 is originally a low-pass filter, so if it can be adjusted to the frequency generated by timpani, almost no electronic circuit filter is required. Also, since there is a resonance frequency, it is conceivable to use a resonance portion with high sensitivity.

The piezoelectric film sensor is preferably installed near the center of the timpani. This is because vibration is limited when a sensor is attached to the opposite side of the strike. The center of the timpani is a portion that theoretically hardly vibrates, but in fact, it was confirmed from the measurement results described later that it vibrates sufficiently to be detected by the sensor.
The structure of the piezoelectric film sensor and the change in the resonance frequency have a correlation shown in FIG. That is, the upper and lower resonance frequencies correlate with the weight of the weight, the distance between the weight and the pin, and the hardness of the piezoelectric film.

Using the same data logger as in Example 1 and its dedicated PC software, the sound of A (220 Hz) was measured with a piezoelectric film sensor.
FIG. 10 is a graph showing a change in voltage when the sound A (220 Hz) is measured while changing the weight of the weight. In FIG. 10A, two weights (about 0.24 g) are arranged at the tip of the piezoelectric film, and in FIG. 10B, one weight (about 0.12 g) is arranged at the tip of the piezoelectric film. In (C), the measurement was performed without a weight.
FIG. 11 is a graph of a frequency spectrum obtained by Fourier transform of FIG. In FIGS. 11A and 11B, a large peak is observed in the vicinity of 223 Hz close to the sound of A. A peak is also observed in the vicinity of 164 Hz, which is presumed to be due to an impact when hit. In FIG. 11C, in addition to the vicinity of 224 Hz, smaller peaks can be observed at 166 Hz and 336 Hz. Here, a new peak at 336 Hz has appeared. This is a third overtone of 112 Hz, which is one octave below the fundamental frequency, so it is not strange that this can be observed.
From FIG. 10 and FIG. 11, it was confirmed that the cantilever type piezoelectric film sensor can obtain a high output without using an amplifier.

Under the same conditions as in Example 3, the G sound (97 Hz) was measured by changing the weight of the weight.
FIG. 12 is a graph showing a change in voltage when G sound (97 Hz) is measured by changing the weight of the weight. In FIG. 12A, two weights (about 0.24 g) are arranged at the tip of the piezoelectric film, and in FIG. 12B, one weight (about 0.12 g) is arranged at the tip of the piezoelectric film. In (C), the measurement was performed without a weight.
FIG. 11 is a graph of a frequency spectrum obtained by Fourier transform of FIG. In FIGS. 13A and 13B, a large peak is seen in the vicinity of 97 Hz close to the G sound. Here, the ratio did not change even when the reverberation was Fourier transformed. In FIG. 13C, no peak could be observed near 97 Hz. This is because when there is no weight, only high frequency components can be picked up.
From FIG. 12 and FIG. 13, it was confirmed that there is a correlation between the weight of the weight and the change in the resonance frequency. In addition, since the sound of G has a low frequency, it was confirmed that it was difficult to measure the distance between the weight of the product and the pin and the hardness of the piezoelectric film without the weight.
In addition, the same tendency was observed in the sound A (110 Hz) one octave lower than in Example 3, and it was confirmed that measurement was difficult without a weight.

Example 5 relates to a timpani tuning device having a curved piezoelectric film sensor.
The piezoelectric sensor 10 of this embodiment includes a piezoelectric film 11 curved in a U-shape, an arm 14 to which the upper surface of the piezoelectric film 11 is fixed, a support portion 15 formed of a rod-like body connected to the arm 14, and a support portion. 15, and a fixing portion 16 provided below 15. The piezoelectric sensor 10 is used by being connected to the first and second amplifiers of the first embodiment by a signal line (not shown) extending from the fixed portion 16. The piezoelectric film 11 has an upper surface, a lower surface, and a curved portion, and is used in a state in which the lower surface is in contact with the timpani head 21 in a posture where the upper surface and the lower surface are substantially horizontal. Here, the lengths of the upper surface and the lower surface do not have to be the same length, and it is sufficient if a certain area of the lower surface contacts the head 21.

As shown in FIG. 14, the piezoelectric sensor 10 can be detachably fixed to a timpani tuning bolt, a frame, or the like by a fixing portion 16. The fixing portion 16 of the present embodiment is an instrument that holds the tuning bolt 22 of the timpani with a spring-biased jaw. The piezoelectric sensor 10 is attached to a position where the lower surface of the piezoelectric film 11 contacts the timpani head 21. Here, it is preferable that the support portion 15 is configured so that the length of the rod-shaped body can be adjusted by a screw or the like.
The arm 14 is configured to have such a length that the piezoelectric film 11 is located at a predetermined distance from the outer periphery (tightening frame) of the head 21.
FIG. 15 is a graph of a frequency spectrum obtained by Fourier transforming the output from the piezoelectric sensor 10 of the present example. 15A shows the result of measuring the sound of G and FIG. 15B shows the result of measuring the sound of E. The former shows a peak at 98 Hz, and the latter shows a peak at 82 Hz. It was confirmed that

 The measurable frequency varies depending on the positional relationship between the piezoelectric film 11 and the head 21. That is, by changing the distance from the outer periphery of the head 21 of the piezoelectric film 11, the measurable frequency is different. Therefore, it is preferable that the length of the arm 14 be adjusted by a screw or the like within the timpani radius range. Further, since the optimum length of the arm 14 is different for each timpani, the piezoelectric sensor 10 having the arm 14 having a length corresponding to a specific model number of each manufacturer may be provided.

  FIG. 16 is a graph of a frequency spectrum obtained by Fourier-transforming the output when the G sound is measured at each position i to iv in FIG. As can be seen from the figure, it can be seen that how peaks appear other than the frequency (98 Hz) to be measured differs depending on the measurement position (distance from the fastening frame). That is, it is possible to confirm that the frequency to be measured can be measured with low noise by selecting the optimum measurement position (position iii in the figure).

1 Upper electrode 2 Piezoelectric material 3 Lower electrode 4 Wiring +
5 Wiring-
DESCRIPTION OF SYMBOLS 10 Piezoelectric sensor 11 Piezoelectric film 12 Pin 13 Weight 14 Arm 15 Support part 16 Fixing part 20 Timpani 21 Head 22 Tuning bolt 23 Frame 24 Kettle

Claims (6)

A flexible sheet-like piezoelectric sensor that converts the vibration of the membrane percussion instrument into an electrical signal;
An arm to which the piezoelectric sensor is fixed and adjustable in length;
A fixing part detachably fixed to the membrane percussion instrument;
A support part for connecting the arm and the fixing part;
An output circuit that amplifies and outputs an electrical signal obtained from the piezoelectric sensor, and a tuning device for a pitched membrane percussion instrument,
The piezoelectric sensor comprises a piezoelectric film sensor having a curved portion and transmitting vibrations of the film to the lower surface,
The tuning device is the fixed portion by the film chromatic pitch of a film is detachably fixed to the ringing percussion characterized Rukoto ringing percussion tuning device. Furthermore, a processing unit that processes an electrical signal obtained from the piezoelectric sensor to determine a pitch name;
Tuning device tinnitus chromatic pitch of the film of claim 1, characterized in that it comprises: a display unit for displaying the determination result by the processing unit, the percussion. Said piezoelectric sensor is, U-shaped perforated interval of claims 1 or 2, characterized in that a piezoelectric film sensor of the film-sounding percussion tuning device. Said piezoelectric sensor is polyfluorinated vinylidene claims 1 to any of the chromatic pitch of the film-sounding percussion tuning apparatus 3, characterized in that it is configured to include a film (PVDF). 5. The tuning device for a membrane percussion instrument having a pitch according to any one of claims 1 to 4, wherein the length of the support portion is adjustable. The film ringing percussion, either organic pitch of the film-sounding percussion tuning device of claims 1 to 5 characterized in that it is a timpani.