JP2006238299A - Passive dynamic equalizer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a passive dynamic equalizer whose reproducing characteristics are satisfactory for compensating hearing characteristics of a human being by a simple configuration. <P>SOLUTION: This passive dynamic equalizer provided with a resistive element whose resistance value increases in proportion to flowing currents, a reactance element serially connected to the resistive element whose impedance changes according to a frequency, and a constant resistive element connected in parallel with the serial connection of the resistive element, is added to a speaker. Thus, it is possible to reinforce a level in a region where the sensitivity of the ears of a human being of a low frequency or a high frequency of a signal to be reproduced by a speaker is deteriorated, and to further reinforce the region according as the reproduction sound pressure level of the speaker is small. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a passive dynamic equalizer. More specifically, the present invention includes a passive element, and is added to a speaker to change the output frequency characteristic of the speaker so as to compensate the human auditory characteristic according to the input signal level. It relates to an equalizer that can.

  In general, buildings such as office buildings are provided with various building facilities, and as one of them, speakers for broadcasting facilities are installed on each floor and each room. The speaker is used, for example, for playing a call broadcast or a BGM broadcast by voice or the like.

  The frequency sensitivity characteristics of human hearing are not flat over the audible frequency range, but vary greatly. Such characteristics are shown by the Fletcher Manson and Robinson Datson iso-loudness curves, or by the international standard ISO226. According to an equal loudness curve diagram showing sound pressure levels that humans feel at equal magnitudes as a function of frequency, human hearing tends to be less sensitive in low and high frequency regions. In particular, in a low frequency region of 200 Hz or less and a high frequency region of 10 kHz or more, the sensitivity of the human ear is greatly reduced as the sound pressure level is lowered. However, since the output sound pressure frequency characteristics of the speaker alone are not designed in consideration of the equal loudness curve, the frequency characteristics of the signal reproduced by the speaker and the frequency characteristics of the signal actually felt by humans are different. In particular, the difference becomes remarkable when the reproduction sound pressure of the speaker is lowered.

  Therefore, for example, if a voice announcement is sent as it is from a speaker, the level of the bass and treble becomes low due to the frequency sensitivity characteristics of human hearing, making it difficult to hear. This tendency becomes more prominent as the playback sound pressure level of the speaker becomes lower. Similarly, when BGM is played, as the playback sound pressure level of the speaker decreases, the level in the low frequency region and the high frequency region can be heard to be low, and good music playback becomes difficult.

  In addition, the above-mentioned speakers for broadcasting facilities are often mounted on the ceiling or wall of a building, and adding an amplifier circuit or the like that requires a power supply circuit to the speakers is a large facility and is expensive. Will cause a problem.

  Accordingly, an object of the present invention is to provide a dynamic equalizer that can compensate for human auditory characteristics and obtain good reproduction characteristics by simply adding a simple configuration to a speaker.

  The passive dynamic equalizer according to the present invention includes means for increasing a resistance value according to a flowing current, and means for changing an impedance according to a frequency. When the passive dynamic equalizer is connected to a speaker, a predetermined signal of a signal reproduced by the speaker is provided. The sound pressure level in the frequency range of the sound is strengthened, the predetermined frequency region is strengthened as the playback sound pressure level of the speaker is small, and the sensitivity of the human ear decreases as the sound pressure level decreases in the predetermined frequency region To compensate. For example, a lamp or a thermistor can be used as a means for increasing the resistance value in accordance with the current.

  In one embodiment of the present invention, a resistance element whose resistance value increases in response to a flowing current, a reactance element that is connected in series to the resistance element and whose impedance changes in accordance with the frequency, and a fixed resistor is connected to the series connection. By adding a passive dynamic equalizer connected in parallel to the speaker, the output frequency characteristic of the speaker is changed according to the input signal level.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic diagram showing a basic configuration of a passive dynamic equalizer of the present invention. In FIG. 1, a passive dynamic equalizer 100 is configured by connecting a resistor 12 in parallel to a series connection of a lamp 10 and an inductor 11, and additionally connected to a speaker 2.

  The filament of the lamp 10 is generally made of tungsten, generates heat in proportion to the value of current flowing therethrough, and increases its resistance value. Therefore, the resistance value of the lamp 10 changes according to the input signal level applied to the input terminals 3 and 4. The impedance of the inductor 11 increases in proportion to the increase in frequency. As a result, as shown in FIG. 2, the total impedance of the speaker system including the passive dynamic equalizer 100 increases as the frequency increases, and at the same time, the impedance in the low frequency region increases as the input signal level increases.

  As the total impedance of the speaker system changes in this way, the voltage applied to the speaker 2 changes as shown in FIG. That is, the level in the low frequency region of the signal reproduced by the speaker 2 is enhanced as compared with the high frequency region, and at the same time, the degree of enhancement in the low frequency region increases as the reproduction sound pressure level of the speaker 2 decreases. Become.

  As described above, the passive dynamic equalizer 100 can correct the reproduction output from the speaker 2 so as to compensate for the frequency characteristics of human hearing described above using only passive elements.

Next, examples based on more specific numerical examples will be described. FIG. 4 shows a circuit for correcting loudness only in a low frequency range using a 4-ohm speaker as a first embodiment of the present invention. In general, a lamp generates heat in proportion to an electric current, and its resistance value increases, and an example thereof is as shown in FIG. 5A. When simulated from this characteristic, it is considered that the voltage-resistance characteristic of the lamp is as shown in FIG. 5B. A 5 mH inductor is connected in series with the lamp, and a 15 ohm resistor is connected in parallel thereto. In this circuit configuration, when the system input voltage _VIN is increased by 6 dB [dB] from 1 volt [V], that is, the input voltage is 1 [V], 2 [V], 4 [V], 8 [V]. ] FIG. 6 shows impedance frequency characteristics of the speaker system when 16 [V]. As is apparent from FIG. 6, the impedance in the low frequency region, particularly in the frequency of 500 Hz or less, increases as the input signal level increases. As a result, the speaker terminal voltage when the system input voltage _VIN is increased from 1 volt [V] by 6 decibels [dB] is as shown in FIG. In FIG. 7, the voltage is represented by [dBV] (1V = 0 dBV). As is apparent from FIG. 7, the voltage applied to the speaker is strengthened in the low frequency region with respect to the high frequency region, and at the same time, the degree of strengthening is higher in the lower system input voltage than in the higher frequency region. ing. FIG. 8 shows sound pressure level frequency characteristics output from the speaker when the passive dynamic equalizer having the configuration of FIG. 4 is actually connected to the speaker.

  In FIG. 4, the speaker is represented as a constant resistance having a resistance value of 4 ohms, but an actual speaker further includes an inductance component and a capacitance component. Therefore, although the speaker itself has frequency characteristics, it is possible to obtain a desired system impedance by selecting a lamp and an inductor in consideration of the characteristics. Furthermore, a more appropriate output frequency characteristic can be obtained by adding a default frequency characteristic adjusting circuit as described later.

FIG. 9 shows a second embodiment in which a capacitor (capacitor) C (1 μF) is connected in parallel to the configuration of FIG. 4 to reduce the impedance in a high frequency region. FIG. 10 shows the impedance frequency characteristic of the speaker system when the system input voltage _VIN is increased from 1 volt [V] by 6 decibels [dB] in the same manner as the characteristic of FIG. Compared with the characteristics of FIG. 6, it can be seen that the system impedance is reduced in the high frequency region. The voltage between the speaker terminals at that time is as shown in FIG. Compared with the characteristics of FIG. 7, it can be seen that the voltage between the speaker terminals increases uniformly in the high frequency region. Therefore, it is possible to compensate for a decrease in ear sensitivity in the low frequency region and to compensate for a decrease in ear sensitivity in the high frequency region, although the degree of enhancement is constant depending on the input level.

FIG. 12 shows a third embodiment in which the loudness correction is performed in the high frequency region and at the same time the decrease in the ear sensitivity is compensated in the low frequency region. In this embodiment, a resistor R (15Ω) and an inductor (5 mH) are connected in parallel to a series connection of a lamp and a capacitor C (2.2 μF). FIG. 13 shows the impedance frequency characteristics of the speaker system when the system input voltage _VIN is increased from 1 volt [V] by 6 decibels [dB]. In FIG. 13, the system impedance is uniformly reduced in the low frequency region, but in the high frequency region, the impedance is lowered as the input signal level is lower. As a result, as shown in FIG. 14, the voltage between the speaker terminals increases uniformly in the low frequency region, whereas in the high frequency region, the voltage increase is strengthened as the input signal level decreases. I understand. Therefore, it is possible to compensate for the decrease in ear sensitivity according to the input level by the loudness correction in the high frequency region, and to uniformly compensate for the decrease in ear sensitivity in the low frequency region regardless of the input level.

FIG. 15 is a schematic circuit diagram showing a fourth embodiment of the present invention which compensates for human auditory frequency characteristics in the high frequency region as well as in the low frequency region. In FIG. 15, the passive dynamic equalizer 200 includes a lamp (LAMP) 20, an inductor 21, and a resistor 22, and a LAMP 23 and a capacitor 24. The LAMP 23 and the capacitor 24 act to lower the system impedance including the speaker (SP) in the high frequency region and to increase the system impedance in the high frequency region as the input signal level increases. Based on the specific numerical example shown in FIG. 15, the impedance frequency characteristic of the speaker system when the system input voltage _VIN is increased from 1 volt [V] by 6 decibels [dB] is as shown in FIG. As is apparent from FIG. 16, the impedance in the low frequency region, particularly at a frequency of 500 Hz or less, is as large as 1 [V], 2 [V], 4 [V], 8 [V], and 16 [V]. It becomes higher as it becomes. At the same time, the impedance in the high frequency region, particularly in the frequency of 10 KHz or higher, increases as the input signal level increases.

As a result, the voltage applied to both ends of the speaker when the system input voltage _VIN is increased from 1 volt [V] by 6 decibels [dB] is as shown in FIG. As is clear from FIG. 17, the voltage applied to the speaker is enhanced in the low frequency region and the high frequency region, and at the same time, the degree of enhancement increases as the system input voltage decreases. Here, by omitting the lamp (LAMP) 20 and the inductor 21, a circuit configuration for correcting the loudness only in the high frequency region can be obtained.

  FIG. 18 is a schematic circuit diagram showing a fifth embodiment of the present invention. In FIG. 18, a passive dynamic equalizer 300 has the same configuration as that of the fourth embodiment shown in FIG. 18, but a default frequency characteristic of a speaker including an inductor 41, a capacitor 42, and a resistor 43 in parallel with the speaker (SP). An adjustment circuit 400 is provided. Speakers generally have their own output frequency characteristics. When a strong output portion (peak) occurs at an unnecessary frequency, good reproduction sound quality cannot be obtained. The adjustment circuit 400 has a function of suppressing the undesired output peak. In the numerical example shown in FIG. 18, it acts to suppress the peak of output around 700 Hz. In FIG. 18, it is also possible to suppress a plurality of peaks by connecting a plurality of adjustment circuits in parallel.

FIG. 19 shows the impedance frequency characteristics of the speaker system when the system input voltage _VIN is increased by 6 dB [dB] from 1 volt [V], and FIG. 20 shows the voltage applied to both ends of the speaker at that time. Indicates. As apparent from FIG. 20, the output sound pressure level in the vicinity of about 700 Hz is suppressed.

  As described above, the passive dynamic equalizer according to the present invention uses only passive elements, and particularly uses the characteristics of the lamp so as to compensate for the characteristic that the sensitivity of the human ear decreases as the sound pressure level decreases. The reproduction output from can be corrected. As a result, an optimum frequency characteristic can be obtained in which the bass and treble parts can be sufficiently heard at any reproduction sound pressure level. Further, when the reproduction level of the bass part is increased, the function of the reproduction output is suppressed, so that the vibration width of the diaphragm is reduced, which is useful for protecting the speaker. In addition, since it uses only passive elements and does not require a power circuit, it can be easily mounted on a speaker mounted on the ceiling or wall of a building and operated with a general-purpose power amplifier with flat frequency characteristics. Can do. In the above description, the lamp is used as having the characteristic that the resistance value increases according to the flowing current value. However, a thermistor or other element can be used as long as it has such a characteristic. It is.

FIG. 1 is a schematic diagram showing a basic configuration of a passive dynamic equalizer of the present invention. It is a figure which shows the total impedance characteristic of the speaker system using the passive dynamic equalizer of FIG. It is a figure which shows the voltage characteristic applied to the speaker using the passive dynamic equalizer of FIG. It is the schematic which shows the Example which utilizes this invention and carries out loudness correction | amendment only of a low region. The current-resistance characteristics and voltage-resistance characteristics of the lamp are shown. The impedance frequency characteristic of the speaker system when the system input voltage _VIN is increased from 1 volt [V] by 6 decibels [dB] is shown. The voltage characteristic between speaker terminals when the system input voltage _VIN is increased from 1 volt [V] by 6 decibels [dB] is shown. It shows the sound pressure level frequency characteristics of the speaker when the passive dynamic equalizer is actually connected to the speaker. It is a schematic circuit diagram which shows the 2nd Example of this invention. In the circuit shown in FIG. 9, the impedance frequency characteristic of the speaker system when the system input voltage _VIN is increased from 1 volt [V] by 3 decibels [dB] is shown. FIG. 9 shows speaker terminal voltage characteristics when the system input voltage _VIN is increased from 1 volt [V] to 6 decibels [dB] in the circuit shown in FIG. It is a schematic circuit diagram which shows the 3rd Example of this invention. In the circuit shown in FIG. 12, the impedance frequency characteristics of the speaker system when the system input voltage _VIN is increased from 1 volt [V] to 6 decibels [dB] are shown. FIG. 12 shows speaker terminal voltage characteristics when the system input voltage _VIN is increased from 1 volt [V] to 6 decibels [dB] in the circuit shown in FIG. It is a schematic circuit diagram which shows the 4th Example of this invention. In the circuit shown in FIG. 15, the impedance frequency characteristic of the speaker system when the system input voltage _VIN is increased from 1 volt [V] by 6 decibels [dB] is shown. FIG. 15 shows speaker terminal voltage characteristics when the system input voltage _VIN is increased from 1 volt [V] to 6 decibels [dB] in the circuit shown in FIG. It is a schematic circuit diagram which shows the 5th Example of this invention. In the circuit shown in FIG. 18, the impedance frequency characteristic of the speaker system when the system input voltage _VIN is increased from 1 volt [V] to 6 decibels [dB] is shown. In the circuit shown in FIG. 18, the speaker terminal voltage characteristics when the system input voltage _VIN is increased by 6 decibels [dB] from 1 volt [V] are shown.

Claims (15)

Means for increasing the resistance value according to the flowing current;
Means for changing impedance according to frequency;
When the speaker is connected to a speaker, a frequency characteristic in which a sound pressure level in a predetermined frequency region of a signal reproduced by the speaker is enhanced can be obtained. Passive dynamic equalizer that provides enhanced frequency characteristics.   2. The equalizer according to claim 1, wherein the means for increasing the resistance value according to the current comprises a lamp.   2. The equalizer according to claim 1, wherein the means for increasing the resistance value according to the current comprises a thermistor.   2. The equalizer according to claim 1, wherein the means for changing impedance according to the frequency comprises an inductor, and the predetermined frequency region is a low frequency region.   2. The equalizer according to claim 1, wherein the means for changing impedance according to the frequency comprises a capacitor, and the predetermined frequency region is a high frequency region. A resistance element whose resistance value increases in accordance with the flowing current;
A reactance element connected in series to the resistance element and having an impedance that increases with frequency;
A constant resistance element connected in parallel to the series connection of the resistance element and the reactance element;
When connected to a speaker, a frequency characteristic with an enhanced sound pressure level in a region where the frequency of the signal reproduced by the speaker is low is obtained, and a lower frequency region is strengthened as the playback sound pressure level of the speaker is smaller Passive dynamic equalizer that provides the desired frequency characteristics.   7. The equalizer according to claim 6, wherein the resistance element is a lamp and the reactance element is an inductor.   7. The equalizer according to claim 6, wherein a capacitor is further connected in parallel to the constant resistance element. A resistance element whose resistance value increases in accordance with the flowing current;
A reactance element connected in series to the resistance element, the impedance of which decreases according to frequency;
A constant resistance element connected in parallel to the series connection of the resistance element and the reactance element;
When connected to a speaker, a frequency characteristic with an enhanced sound pressure level in a region where the frequency of the signal reproduced by the speaker is high is obtained, and a higher frequency region is strengthened as the playback sound pressure level of the speaker is smaller Passive dynamic equalizer that provides the desired frequency characteristics.   10. The equalizer according to claim 9, wherein the resistance element is a lamp and the reactance element is a capacitor.   10. The equalizer according to claim 9, wherein an inductor is further connected in parallel to the constant resistance element. A first series connection of a first resistance element that increases in resistance according to a flowing current and a reactance element that is connected in series to the first resistance element and increases in impedance according to frequency;
A second series connection of a second resistance element that increases in resistance according to a flowing current and a reactance element that is connected in series to the second resistance element and decreases in impedance according to frequency;
A constant resistance element connected in parallel to the first series connection and the second series connection, and further connected in parallel to the parallel connection;
When the speaker is connected in series, a frequency characteristic with enhanced sound pressure level in the low frequency region and high frequency region of the signal reproduced by the speaker can be obtained, and the lower the reproduction sound pressure level of the speaker, A passive dynamic equalizer capable of obtaining frequency characteristics in which the low frequency region and the high frequency region are enhanced.   13. The equalizer according to claim 12, wherein the first and second resistance elements are lamps, a reactance element whose impedance is increased according to the frequency is an inductor, and a reactance element whose impedance is decreased according to the frequency is Passive dynamic equalizer consisting of capacitors.   13. The equalizer according to claim 12, further comprising a default frequency characteristic adjusting circuit that can be connected in parallel with the speaker.   15. The equalizer according to claim 14, wherein the default frequency characteristic adjusting circuit includes an inductor, a capacitor, and a resistor.

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