Electrostatic pickup

Abstract

The invention relates to electrostatic pickups for improving the sound quality of string musical instruments. An electrostatic pickup comprises an instrumentation amplifier (7) with a high input impedance, a polarizing voltage source (5), and two capacitive sensors (1, 2), each of which consists of a sensor (6) and a polarizing electrode (4). Said sensor is connected to an input of the instrumentation amplifier via a balancing resistor (8), wherein the resistor is connected in between the input of the instrumentation amplifier and a neutral point. The polarizing electrode is connected to the polarizing voltage source, wherein an effective signal is picked up from the output of the instrumentation amplifier. The result is that of eliminating the negative effect of a magnetic field on the vibration of the strings and preventing the skewing of the sound signal toward low frequencies.

Description

[0001] ELECTROSTATIC PICKUP

[0002] The invention relates to the field of devices, namely to stringed musical instruments intended to improve the sound quality of electric guitars made of wood, and can also be used in the design of other musical instruments, the source of sound vibrations in which are strings, which are used to convert sound vibrations into electrical signals.

[0003] PRIOR ART

[0004] From the prior art, electromagnetic pickups are known, installed under the strings of an electric guitar, consisting of a permanent magnet, a core made of magnetically soft iron and a coil with a large number of turns of thin enameled copper wire, in which, when the strings vibrate, an electromotive force (EMF) is generated, which is fed to the input of an electronic amplifier.

[0005] The main disadvantages of electromagnetic pickups are nonlinearity of the amplitude-frequency characteristic (AFC), limited range of reproducible frequencies, and the influence of the magnetic field on string vibrations.

[0006] Electromagnetic pickups are known, consisting of two multi-turn coils on the pole pieces of a permanent magnet, connected in series or parallel and connected to the input of an amplifier, which amplifies the EMF of the coils. Such pickups, called humbuckers, are produced by DiMarzio, Gibson, Seymour and others. Compared with single-coil pickups, humbuckers, consisting of two inductance coils in a magnetic field, have improved APH in the high-frequency range and improved noise immunity, although these improvements are insignificant and do not eliminate the main disadvantages of pickups with high inductive resistance of coils using electromotive force as a signal.

[0007] Electromagnetic sound pickups are known that include an induction coil with a permanent magnet (RU Patent for Invention No. 2289857 C1, 2006.12.20, published 20.12.2006 Bulletin No. 35). The sound pickup according to Patent No. 2289857 is connected to an electronic amplifier, contains an induction coil with a permanent magnet and flat pole pieces, wherein the pole pieces (cores) are attached to opposite poles of the permanent magnet and are spaced 3-4 mm apart, and the induction coils (signal coils) are wound with insulated wire, connected in series and connected to the input of an active amplifier with parallel negative feedback.

[0008] The disadvantage of such a pickup is the bias of the audio signal spectrum towards low frequencies, which is a consequence of high internal resistance, high inductance of the coils and high inter-turn capacitance, since the coils have significant dimensions and a large number of turns.

[0009] As the resistance increases, the pickup becomes more powerful, but inevitably loses high frequencies and sound transparency. The internal resistance of the pickup can be reduced by increasing the diameter of the winding wire or reducing the number of turns of the coils, but this will lead to an even greater increase in dimensions and a decrease in EMF. Another disadvantage of the described pickup is the low rate of increase of the useful signal. The rate of magnetization and remagnetization of the massive pole pieces on which the inductance coils are wound greatly affects the dynamics of the alternating voltage arising in the coil, that is, the effect begins to manifest itself already at frequencies of 1500 - 2000 Hz, and dynamic and frequency-phase distortions of the useful signal occur. In addition, electromagnetic pickups can only work with strings made of ferromagnetic materials, while strings based on non-ferrous metals give a brighter and richer sound.

[0010] There is a great need for stringed musical instruments that can produce quality sound regardless of the wood and string materials from which the instrument is made.

[0011] The most promising for such purposes are electrostatic or capacitive pickups - devices that convert string vibrations into an electrical signal (changing electrical capacitance) using capacitor sensors. Changes in capacitance are proportional to the fluctuations of the measured value, and this correspondence allows you to track its behavior. The operating principle of any capacitor sensor that perceives external non-electrical effects and responds to them by changing electrical signals is associated with a change in its parameters, this can be a change in the gap between the capacitor plates due to their convergence or removal (https: / / osensorax.ru / posiciya / emkostnoj-datchik).

[0012] The technical problem that the development of the pickup is aimed at solving is the elimination of the negative influence of the magnetic field on the vibrations of the strings and, as a consequence, the elimination of the distortion of the sound signal towards low frequencies.

[0013] DISCLOSURE OF INVENTION

[0014] The technical result consists in improving the sound quality of a string musical instrument due to a more accurate transmission of the entire spectrum of string vibrations, and, as a consequence, the possibility of using strings based on non-ferrous metals, which give a brighter and richer sound. The technical result is achieved by using an electrostatic pickup installed under the strings of an electric guitar, consisting of two capacitor sensors, the capacitance of which changes proportionally to the distance between the string and the sensitive element - a sensor located in the electrostatic field of a capacitor formed by the strings of a musical instrument and an electrode connected to a source of polarizing voltage.In this case, changes in the electric field are recorded by the sensors of each of the two capacitor sensors and fed to the input of an instrumentation amplifier with high input resistance, with the instrumentation amplifier connected through a balancing resistor, and the useful signal is removed from the output of the instrumentation amplifier.

[0015] An electrostatic pickup, installed near the source of sound vibrations, contains an instrument amplifier with high input impedance, a source of polarizing voltage and two capacitor sensors, each of which consists of two electrodes, one of which

[0016] — a sensor that is connected to the input of the instrumentation amplifier through a balancing resistor connected between the input of the instrumentation amplifier and the zero point, and the second

[0017] - the polarizing electrode is connected to a source of polarizing voltage, while the useful signal is removed from the output of the instrument amplifier.

[0018] The sensor of the detector can be placed above the polarizing electrode.

[0019] One design option is that the polarizing electrode surrounds the sensor with a ring.

[0020] The polarizing voltage source is made single-pole, ensuring the removal of sound vibrations at one point of the sound vibration source.

[0021] In another embodiment, the polarizing voltage source is made bipolar, ensuring the removal of sound vibrations at two points of the sound vibration source.

[0022] BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0023] The claimed solution is presented in the following drawings:

[0024] Fig. 1 - a block diagram explaining the claimed solution;

[0025] Fig. 2 - diagram of signal pickup at one point on the string; Fig. 3 - diagram of signal pickup at two points on the string;

[0026] The block diagram explaining the claimed solution (Fig. 1) includes:

[0027] 1 - first capacitor sensor;

[0028] 2 — second capacitor sensor;

[0029] 3 - strings of a musical instrument.

[0030] 4 — polarizing electrode;

[0031] 5 - polarizing voltage source (one for 2 sensors);

[0032] 6 — sensitive element (sensor);

[0033] 7 - instrumental (measuring) amplifier (one for 2 sensors);

[0034] 8 - balancing resistor.

[0035] The claimed electrostatic sound pickup contains two capacitor sensors (1) and (2), the preferred installation options of which relative to the strings (3) of the electric guitar are shown in Fig. 2 and Fig. 3 - depending on the preferences of the guitarists performing the music.

[0036] The string (3) together with the polarizing electrode (4) connected to the source of polarizing voltage (5) form a variable capacitor, the capacitance of which changes proportionally to the distance between the string (3) and the polarizing electrode (4). When the distance between the string (3) and the polarizing electrode (4) changes, the capacitance between the plates of the variable capacitor changes, these changes are recorded by the sensors (6) of each of the sensors connected to the input of the instrument amplifier (7) with a high input resistance (at least 10 GΩ) through balancing resistors (8) with a nominal value of several GΩ. Possible design options for each capacitor sensor implementing the operation of the electrostatic pickup depend on the location of the sensor (6) relative to the polarizing electrode (4).

[0037] According to the first preferred embodiment of the capacitor sensor, the sensor (6) is located between the string (3) and the polarizing electrode (4).

[0038] According to a second preferred embodiment of the capacitor sensor, the sensor (6) is located in close proximity to the electrode (4) or surrounds it with a ring.

[0039] In this case, the device, according to the invention, operates as follows.

[0040] The signals taken from the sensors (6) of the sensors (1) and (2) are fed to the input of the instrumentation amplifier (7) and subtracted, as a result of which the common mode interference induced on them is suppressed, which is the same in magnitude due to the close location and identical geometry of the sensors (1) and (2).

[0041] There are 2 possible options for installing electrostatic pickups relative to the source of sound vibrations:

[0042] According to the first variant (Fig. 2) of installing the sensors - spaced sensors (1) and (2) remove vibrations at one point of the string, which allows for more reliable signal conversion and a brighter sound coloration, closer to the sound of an acoustic instrument, this gives a more natural sound and is suitable for performers in the direction of jazz, blues and similar music. In this case, it is sufficient to use a unipolar source of polarizing voltage, which simplifies the design of the pickup as a whole, but provides lower sensitivity than the variant with two pickup points.

[0043] According to the second variant (Fig. 3) of installing the sensors, the signal is picked up at two points of the string, which requires the use of a bipolar source of polarizing voltage. Different polarities of the electrostatic field on sensors (1) and (2) ensure antiphase pickup of useful signals, while the signal is picked up at two points of the string, which introduces some distortions in the high-frequency range, cutting them off, but increases the sensitivity of the device in the low and medium frequency range by subtracting antiphase signals. This version of the design will be in demand among musicians performing heavy energetic music.

[0044] Thus, the solution to the stated problem is provided in the declared device by the following features:

[0045] - the presence of two identical sensors;

[0046] - the presence of a polarizing voltage source (one for 2 sensors); a circuit for supplying polarizing voltage to the polarizing electrodes;

[0047] - the location of the sensor relative to the polarizing electrode; the circuit for feeding signals from the sensors to the input of the instrumental amplifier. The claimed solution is disclosed in relation to preferred embodiments of its implementation, however, similar variants are also possible that do not go beyond the scope of legal protection of this solution.

[0048] INDUSTRIAL APPLICABILITY

[0049] Structurally, the declared pickup is simple to manufacture, the body has the form of an elongated plate of rectangular cross-section, inside which there are printed circuit boards with the necessary elements.

[0050] The claimed device allows achieving a technical result, effectively suppresses external interference, has high reliability of useful signal transmission in a wide frequency range, high stability of operating characteristics, while expanding the list of materials being removed, without affecting the vibrations being removed.

[0051] Advantages of the declared solution:

[0052] - improving the quality and reliability of audio signal transmission;

[0053] - the string material can be made of any material;

[0054] - small weight and dimensions;

[0055] - low power consumption;

[0056] - ease of manufacture, use of available, inexpensive materials.

[0057] The claimed technical solution meets the criterion of “industrial applicability”, since it can be manufactured from known materials and by known methods.

Claims

1. An electrostatic sound pickup, installed near a source of sound vibrations, characterized in that it contains an instrument amplifier with a high input impedance, a source of polarizing voltage and two capacitor sensors, each of which consists of two electrodes, one of which - the sensor - is connected to the input of the instrument amplifier through a balancing resistor connected between the input of the instrument amplifier and the zero point, and the second - the polarizing electrode - is connected to the source of polarizing voltage, wherein the useful signal is removed from the output of the instrument amplifier.

2. An electrostatic sound pickup according to claim 1, characterized in that the sensor of the sensor is placed above the polarizing electrode.

3. An electrostatic sound pickup according to claim 1, characterized in that the polarizing electrode surrounds the sensor of the sensor with a ring.

4. An electrostatic sound pickup according to paragraph 1, characterized in that the polarizing voltage source is made single-pole, ensuring the removal of sound vibrations at one point of the sound vibration source.

5. An electrostatic sound pickup according to paragraph 1, characterized in that the polarizing voltage source is bipolar, ensuring the removal of sound vibrations at two points of the sound vibration source.

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