DE1762585A1 - Furnishing microphone - Google Patents

Description

It 103 *

Sony Corporation (Sony Kabushikikaisha), Tokyo / Japan SItBITStMSStStStItIMMBtHIStHIIMtMBIMMMlUl Setup »-microphone

The invention relates to an indication microphone, In particular, a built-in microphone that widen your head Frequency range a uniform response behavior and a narrow

Has directional characteristic.

In the production of cinema or television films, it is desirable Hold the microphone outside of the picture so that it is not visible · When using conventional microphones, they are annoying Noises and reflected sound waves In the mine of the microphone « the desired «audio signal to be recorded» counteract this, Directional earphones such as pressure or vell-type microphones or pressure-lent-type directional microphones have been used. The pressure or wave type microphone possesses an embossed Directional effect and “In good Frequens response behavior in the lower frequency range; on the other hand is its dependence on direction and its frequency response is maintained in the medium and high Frequensbereioh very bad. On the other hand, a Druokgra " serves-type-Rlohtungsmikropbon la medium and high frequency range a pronounced reddening effect, but not in the lower one Frequensberel Ah. . . . . ^

009827 / 0.566 BADORiaiNAL

The invention eliminates the shortcomings of the known exercises alt with the help of a microphone »small dimensions, you upper one wide frequency range a uniform and narrow directional effect and a smooth Frequene-Adeprecbverbalten »elgt. To this The purpose may be a pressure or wave-type radio microphone and a pressure grade lent-type directional microphone with each other combined. The combination is done so that with a proportionate small pressure or wave type directional microphone one ssbr good direction dependency and a good frequency response In the lower frequency range it is realized while with @ ißi @ a Dru ^ kgradlent-type Rlebtungamlkrophon of the middle and high Frequensbereiob is detected; this way you get a combined Microphone of relatively small construction and high directional effect, the over the whole listening area a linear frequency * - Response behavior is increasing. ^

These and other features of the invention are evident from the following Description of some of the design elements illustrated in the drawing. Bs bliss

Flg. 1 shows a schematic representation of the microphone according to the invention;

Pig 2 shows an enlarged detail of the one according to the invention Microphone graded pressure or wave-type radiation microbones; ■.

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BATH ORIGINAL

Fig. 3 is a schematic representation of a further embodiment. Game of invention;

• H is a diagram showing the frequency behavior of the two-order "direction gradient" type microphone of the embodiment of FIG. 1;

. 5 is a diagram showing the frequency response of the line mlkrophones of Fig. 1 Teransohaulioht;

Fig. 6 a Dlagraa *, weiehes the frequency behavior of the Einriehtungsaikrofons Fig. i shows;

7 is a diagram showing the characteristics of the band filters of the microphone ·· gea & A Fig. 1 reranahaulicht;

Flg. 8 the Riohtungeo character of a well-known Elnriohtungs-Hikropbone;

9 shows the directional character of the microphone according to the invention. the Flg. 1.

The invention relates to a small old microphone and narrow directional image with smooth frequencies (fter a wide range of frequencies.

009827/0556 bathroom

1 shows a device microphone arrangement which contains a pressure gradient type microphone 1 in wave type or line alcohol 2 in combination. The microphone is supposed to detect sound waves 5 that coan from a certain direction; the microphone is aligned with the sound source of the sound waves 5. The world-class pressure gradient-type microphone 1 contains a pair of condenser microphone capsules 3 and 4, which have an angle character (see FIG. B) along their directional axis 5 and are separated by a distance D ₁ . The distance D ₁ can for example be 30 to. 40 be approx; the capsules 3 and 4 can have the same characteristics. The oleiohstrosi bias of the microphone capsules 3 and k is of opposite polarity, so that there is a difference between the output signals of the espeins 3 and 4. The output of the microphone 3 is connected via capacitors 10 and 11 to the gate electrode of a field effect 12. The output of the microphone capsule 4 is

the capacitor 11 to the gate electrode of the field effect translator 12 connected. The capacitors Io and 11 hold the DC voltage components in the output signals of the microphone capsules 3 and 4 far.

The Leltungsalkrophone 2 is a microphone of the wave type and contains an acoustic pipe 13 along the directional axis 5 * of which front end 13a is closed. Bine Ansah! from acoustlsohen

009827/0556 badORIQINAL

Holes 1 * 1 are arranged along the acoustic pipe 13. This At the end facing away from the end 13, the ear 13 has a chamber 13b which has a condensate microphone capsule 15.

Wi @ is best seen in Fig. 2, © ind the holes 14 of the iiSmsfö Ischen tube 13 is pot-shaped; its axis lies 2 »® @ htwinklig sur the longitudinal axis of the pipe 13 * In the bottom of the

A, there are breakthroughs through which the sound waves I the pipe 13 can enter. The holes 1 * 1 are so formed that they resonate at about 10 IcHs; they are with acoustic insulating material 16 filled, for example FlIs or suitable material.

The microphone capsule 15 is connected to the polarization voltage source 6 connected via a resistor 20. The pressure gradient type microphone 1 and the line microphone 2 are accommodated in a common housing 17, which is illustrated by dashed lines 1st. They are provided in such a way that they detect the sound waves coming from the direction of the path.

The frequency components of the pressure gradient-type microphone 1 detected audio signals are combined with the medium and high frequency components of the line microphones. to this purpose is the output of the microphone capsule 15 of the line microphone 2 old of the gate electrode of the field effect transistor 19

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ühev a capacitor 18 connected. The collectors of the field effect transistors 12 and 19 are connected to one another and to a voltage source 21, the other pole of which is grounded. The emitters of the field effect transistors 12 and 19 are via resistors 22 BSW. 23 grounded. The arrangement thus forms a source follow-up circuit. The emitter of the transistor 12 is provided with a capacitor 24

i, the other terminal of which is connected to a low-pass filter 25 which contains a coil L * and a capacitor CL. The emitter of transistor 19 is connected to a high-pass filter 26 which contains a capacitor C ₂ and a coil L ₂ . The output of the high-pass filter 26 is connected to one end of the primary winding 27a "ines transformer 27, the medium voltage of which is grounded. The other end of this primary winding 27a is connected to the output of the low-pass filter 25. The cut-off 9r @ quensen of the filters 25, 26 are chosen to be approximately the same.

The secondary winding 27b of the output transformer 27 is connected to the output terminals 28a, 28b to which a suitable ([not shown ·) Groove device is connected ·

The field effect transistors 12 and 19 and the filters 25, 26 are arranged in a shield 29. The circuit used for the output of the two microphones is a total of the combination

BATH ORIGINAL ι

00982 77 * 0 5

denoted by reference numeral 30.

Flg. 4, the Frequensverhalten shows the illustrated in Fig. 1 pressure gradient type microphone 1. The fully drawn curve, denoted with the label 9 ¹ SO ^0, corresponds to the sound waves impinging on the capsules 3 and 4 in the direction of the arrow 5 ( see Flg. 1). If one denotes ^{the wavelength of the sound waves with 1} K and if the distance D * equals ^, then the output signal of the capsules 3 and 4 corresponds to the sum and one obtains the i highest sensitivity. If the distance D ₁ «ηλ (where η is a positive integer), then the sensitivity is greatly reduced and deep valleys appear in the characteristic curve (cf. Fig. 4, right). If a sound wave hits the capsules 3 and 4 from the side, a result is obtained as shown by the dashed curve 0 «90 °. In this case, the output signals of the capsules 3 and 4 are offset from one another, since they always have the same amplitude and opposite phase, regardless of the distance D ₁ .

¹ (

If the sound waves hit the microphone 1 from behind, the output signals from the capsules 3 and 4 almost completely disappear, since the capsules themselves have a device characteristic according to FIG. 8. This is in Flg. 4 represented by the dashed curve Ö * 180 °. As the curve 0 «0 ° shows, a favorable directional characteristic is obtained for frequencies at which the wavelength is less than D _1.

009827/0556

The line microphone 2 has a frequency curve as shown in Flg. 5 can be seen 1st. The microphone corresponds to a parallel connection of a plurality of acoustic impedance tubes of different lengths. Like Flg. 5 shows, a favorable directional effect is obtained at the higher frequencies, while almost no directional characteristic occurs in the lower frequency range. The full curve 0 * 0 ° for sound waves arriving in the direction of arrow 5 (FIG. 1) has, for example, a significantly larger output signal than the curves θ «90 ° and θ = 180 ° above the frequency i * _c . The frequency f _{Q is} that frequency at which the entire useful length D ₂ (corresponding to the distance ds between each hole 14 multiplied by the number of holes) corresponds to half the wavelength of the incoming sound waves. Although the directional dependence at a frequency f _R , the de> | If the distance ds between the holes 14 of 30 mm and below is selected, a frequency f _n * 8 to 10 kHz is obtained, which does not pose any problems in practical use.

It is therefore desirable to determine the values of the cut-off frequency f _{er of} the low-pass filter 25 and the high-pass filter 26 in such a way that the frequency ranges of the microphones 1 and 2 partially overlap, which results in a favorable directional characteristic.

Flg. 6 shows the frequency behavior of the combined output signals of microphones 1 and 2. It can be seen that one obtains a spatial character across the entire frequency band.

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Xn Fig. 7, the characteristics of the filters 25 and 26 are illustrated. The curve 32 shows the characteristic of the low-pass filter 25 and the curve 31 the characteristic of the high-pass filter 26 again. Fig. Geigt the frequency behavior at f _cr - 1 kHz when using filters 25 and 26 with the characteristics according to FIG. 7 and at distances D ^ s 350 mm and D ₂ ^s Ί50 mm.

It can be seen from FIG. 6 that the curves θ = 90 ° and θ = 180 ° Have output signals that are significantly smaller than those of the curve θ s o °; The combined microphone therefore owns the whole Listening area both a good directional effect and a uniform output signal.

The microphone according to the invention therefore has a directional characteristic both in the low-frequency range and in the high-frequency range. Since the distance D ₁ between the capsules 3 and Ί of the secondary pressure gradient-type microphone 1 can be about 30 to 40 cm and the length of the acoustic tube 13 of the line headbone 12 can be about 50, the entire microphone system is relatively small. The outside diameter of the acoustic pipe 13 of the Leltungs- ■ ikrophonee 2 can be about 8 mm; the space requirement of the microphone is therefore very small.

Maybe · Bapfindllohkeltsdifforensen between the microphones 1 and 2 can by means of the microphone capsules 3, * and 15 supplied Polarization voltages as well as «with the help of the pelde effect

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transistors 12 and 19 supplied voltage are balanced. You can also use the capsules 3, * and 15 microphone capsules of the same select general characteristics.

Flg. 8 shows the directional characteristics of the line microphones according to the known prior art, plotted in polar coordinates. Fig. 9 on the other hand, shows the directional characteristics of the Mlkrophones invention having the same length (W examples game, 60 cm) having as the known line microphone whose characteristic in Flg. 8 is illustrated. If one compares the two representations, one can clearly see that the microphone according to the invention has a significantly more pronounced directional characteristic in the lower frequency ranges (cf. the frequencies of 50 Hz, 100 Hz, 500 Hz, etc.). The invention thus achieves a significant improvement in the directional characteristic.

Fig. 3 shows another embodiment of the invention, in which two capsules 3 and 15 are provided instead of the three capsules used in FIG. In Fig. 3 are used to denote the the same elements have the same reference numbers as in FIG. 1 used. The capsule 15 of the embodiment shown in FIG. 3 serves as a Part of the pressure gradient type microphones and the wave type microphones. The Auegangsiignal the capsule 15 is through the high pass filter 26 and the capacitor 18 of the gate electrode of the field effect transistor 19 and via the intn low-pass filter 25 * (the old de "low-pass filter 25

009827/0556

-I-

identical 1st) and the capacitor 11 of the gate electrode of the field effect transistor 12 is supplied. The output signal of the capsule 3 is fed to the gate electrode of the field effect transistor 12 via the low-pass filter 25 and the capacitors 10 and 11. The outputs of the capsules 3 and 15 together form a secondary pressure gradient type microphone. The capsule. 15 receives a bias voltage from the voltage source 7 via the resistor 9, while the capsule 3 receives a bias voltage via the resistor 8 from the voltage source 6. The bias of the capsules 3 and 15 are of opposite polarity so that the secondary pressure gradient type microphone provides a differential output signal which is fed to the gate electrode of the field effect transistor 12. The capsules 3 and 15 thus form a secondary gradient Microphone which is equivalent to capsules 3 and H in Fig. 1. The capsule 15 also serves as the output of the mode microphone 2 and feeds the output signal to the gate electrode of the field effect transistor 19 via the capacitor 18.

The combined output signals from the two microphones appear at ports 28a and 28b. The in Flg. 3 illustrated The unidirectional microphone therefore has the same characteristics as the unidirectional microphone in FIG. 1.

Although capacitor type microphone capsules can be used for <AEIE capsules 3, 4 and 15, so instead, any other types of dynamic microphones or tape-type micro phon® are used. "

0-09827 / 0566.

Claims (1)

- .17 £ 25 aS Claims ί IΛ Einriohtunga microphone, characterized in that a second-order degree microphone is provided, which is a pair Has gradient microphone elements which have such a distance from one another that they have approximately the same directional dependence and generate a composite output signal that. Furthermore, a mode microphone is provided, the directional dependence of which is essentially related to that of the first-mentioned microphones, and that there are also devices for combining the output signals of both microphones, which combine the low- frequency components of the second-order microphones with the medium-frequency and high-frequency components of the Combine wave type microphones. -2.) A device microphone according to claim 1, characterized in that that the light type microphone includes an acoustic tube that extends over e @ in <s longitudinal direction distributed a multiplicity of spaced-apart has acoustic holes and is closed at one end, and that at the other end of this acoustic tube an EIn * «-Directional microphone element is arranged. 3 ·) Einriebtungs-microphone according to claim 1, characterized in, that the wave-type microphone contains an acoustic tube, which over its longitudinal direction a plurality of spaced-apart 009827/0556 akusfc! has holes and a closed end, further- with the other end of this acoustic tube ί-Mlkx-ophon element is connected, and that this i element as one of two gradient microphone elements & <§ © Second-order gradient microphones »is used. ^ So) ice direction microphone according to claim 1, characterized marked, that the devices for signal combination have a Tlefpassfil-, A high-pass filter and a combining the outputs of the filters Output transformer included, with the output signal of the second-order oradient microphone, the low-pass filter and the output signal of the cell-type microphone becomes the high-pass filter. 5 »} unidirectional microphone according to claim 1, characterized in that ü && a Rlchtungs-shaft type Mlkrophon provided is a valve disposed next to this shaft-type microphone Riohtungs-Second Trim Qradient microphone which is aligned so that both microphones the same Rlchtungsabhlnglgkelt besltsen, because combination devices are also connected to the two microphones, which have a high-pass filter and a low-pass filter, the output of the second-order microphones being connected to the low-pass filter and the output of the wave-type microphones being connected to the high-pass filter, and the low-pass and high-pass filters are connected to output ports are· 009827/0556 - IH - 6.) Einriehtungs microphone according to claim 5 »thereby marked, daA ewei field effect transistors are provided, of which the @ine between the low-pass filter and the second-order gradient microphone is switched, while the wide transistor is arranged between Sem Hoohpamfliter and the Velle-type microphone. 7 ·) A device microphone according to claim 5 »characterized in that »<$ & Ä the second oritoungsgradlent-Mlkrophone swei by the distance V ·: .- " Ir ^ - D ^ contains separate microphone elements with which there is a device which biases the microphone elements with the opposite. . ^: One-way microphone according to Claim 5, characterized in that d & s wave type microphone contains an acoustic tube that carries a End having a number of spaced angeordaktastisohen Openings distributed over its longitudinal direction and a microphone element is provided at the other end thereof / ■■■ -V · ^. 9.) Einriehtungs microphone naoh claim 8, thereby gekennseiohnct, daA one of the two microphone elements through the tube on the provided microphone element is formed. 10.) A directional microphone according to claim 8, because the length D _{2 of the} pipe is greater than D ₁ . 0 0 a.8 2.UQ 5 5 6 bad original