JP4528573B2 - Condenser headphones - Google Patents

Description

  The present invention relates to a condenser headphone having a push-pull type electro-acoustic transducer, and more particularly to a polarization voltage output unit that applies a polarization voltage to the electro-acoustic transducer.

There are two types of electro-acoustic transducers used for condenser headphones: a single type with a fixed pole on one side of the diaphragm and a push-pull type with fixed poles on both sides of the diaphragm. Since there is a problem in lowering the resonance frequency (f ₀ ), it is difficult to realize a full-band type. Most of the capacitor headphones currently in practical use are push-pull types as disclosed in Patent Document 1. It is.

  FIG. 2 shows a cross-sectional view of a configuration example of a conventional push-pull capacitor headphone. FIG. 3 is a schematic diagram showing the drive system. According to this, the capacitor headphone includes a headphone housing 10 that is supported by the headband 1 and attached to the ear part of the listener as a basic configuration.

  The headphone housing 10 is formed of a bottomed cylindrical body whose support side by the headband 1 is closed, the opening side addressed to the ear part of the listener is covered with a perforated plate 11, and an ear pad is provided on the periphery of the perforated plate 11. 12 is attached. In the case of the open air type, a sound emitting hole is also provided on the side surface of the housing on the support side by the headband 1.

  A push-pull type electro-acoustic converter 20 as a speaker is accommodated in the headphone housing 10. That is, the electro-acoustic transducer 20 includes a diaphragm 21 stretched in a state where a predetermined tension is applied to the support ring 22 and a pair of left and right fixed members disposed on both sides of the support ring 22 via spacer rings (not shown). And poles 23 and 24. In the headphone housing 10, an acoustic damper material 25 may be disposed on the back side of the electro-acoustic converter 20.

  For the diaphragm 21, for example, a very thin polymer film (for example, about 1.2 μm) such as polyethylene terephthalate (PET), polyphenylene sulfide (PPS), or polyethylene naphthalate (PEN) is used. Conductivity is given by the above. The support ring 22 is made of a conductive material such as a brass alloy.

  For the fixed poles 23 and 24, a metal plate such as a brass alloy or aluminum having a large number of holes for emitting sound is used. In many cases, a polymer film is charged on the surface facing the diaphragm 21. An electret material obtained by processing is applied.

  With reference to FIG. 3, the diaphragm 21 is connected to a polarization power source (DC power source) 31 through a high resistance 32. The audio signal is input from the primary side winding 33 a of the transformer 33, and the fixed poles 23 and 24 are connected to both ends of the secondary side winding of the transformer 33. As a result, signal voltages of the same level with opposite phases are applied to the fixed poles 23 and 24, and the diaphragm 21 vibrates by push-pull drive.

  The high resistance body 32 keeps the role of a protective resistor that prevents discharge from occurring when the diaphragm 21 is mechanically contacted with the fixed poles 23 and 24 with a large amplitude, and the charge of the diaphragm 21 is kept constant. It is used for the role of reducing third-order distortion.

JP 58-27720 A

  In a capacitor headphone, normally, a polarization voltage of about 500 V is applied to the diaphragm 21 from a polarization power supply 31. Since the polarization voltage is such a high voltage, the polarization power supply 31 is conventionally built in a headphone additional device called an adapter or a dedicated headphone amplifier, and the polarization voltage is obtained therefrom.

  Therefore, as shown in FIG. 2, the power cable 42 is pulled out from the headphone housing 10 in addition to the signal cable 41. However, when a connector (not shown) of the power cable 42 is connected to the adapter or the dedicated headphone amplifier described above, Touching the connection terminal etc. is dangerous because it may cause an electric shock.

  In addition, since the distance from the polarized power source to the headphone housing 10 is long, the polarized voltage may leak from, for example, a connection portion in the middle, and a large noise may occur. In particular, it has been pointed out that the noise generation rate increases because leakage tends to occur in a high humidity environment such as rain.

  On the other hand, the variation in the output sound pressure between the left and right headphone units is a serious problem in stereophonic sound because the sound image becomes unstable. The variation in the output sound pressure (sensitivity) is caused solely by the assembly accuracy of the electro-acoustic transducer 20 (for example, the distance between the diaphragm and the fixed pole).

  Therefore, at the assembly site, after measuring the acoustic performance of the headphone unit alone and selecting the sensitivity, the headphone units with almost the same sensitivity are combined. This is a problem in terms of product yield.

  Accordingly, an object of the present invention is to increase the safety in use of capacitor headphones and to adjust the output sound pressure (sensitivity) as necessary.

In order to solve the above problem, the invention according to claim 1 is a push-pull type electro-acoustic conversion in which a pair of left and right fixed poles are arranged on both sides of a diaphragm provided with conductivity via a spacer ring. a headphone housing vessel is built, the electro - in the condenser headphones and an audio signal input unit for inputting the polarization voltage output unit and the audio signal to provide a polarization voltage to the acoustic transducer, the headphone the housing has a voltage doubler rectifier type converter that generates the polarization voltage from a predetermined low DC voltage source as the polarization voltage output unit is housed, the positive side voltage doubler rectifier unit for the converter and negative times A voltage rectifying unit, and a battery is used as the DC low voltage source, and an oscillator that outputs a DC voltage supplied from the battery as an AC voltage is provided at the input stage of the converter. The positive side voltage rectification unit gives a positive polarization voltage obtained by voltage rectification of the positive half-wave of the AC voltage to the one fixed pole, and the negative side voltage rectification unit gives the positive voltage. A negative polarization voltage obtained by voltage rectifying the negative half-wave of the AC voltage is applied to the other fixed pole, and the sound is input between the diaphragm and each fixed pole from the sound signal input unit. It is characterized in that a signal is input .

According to a second aspect of the present invention, in the first aspect , an intermediate tap is drawn from a predetermined rectification stage included in the plus-side voltage doubler rectifier and the minus-side voltage doubler rectifier, and the intermediate tap is It is characterized in that a polarization voltage can be applied to each fixed pole.

According to a third aspect of the invention, as characterized by Oite to the claim 1 or 2, the input stage of the converter input voltage adjusting means for adjusting the voltage level of the DC low voltage supply is provided Yes.

  According to the first aspect of the present invention, since the polarization voltage output unit is housed in the headphone housing by the double voltage rectification type converter that generates the polarization voltage from a predetermined DC low voltage source, When supplying polarized power, the voltage may be about 5 V, for example, and an electric shock accident can be prevented.

  In addition, since the polarization voltage output unit is disposed close to the electro-acoustic converter, noise generation due to leakage of the polarization voltage is greatly reduced. In addition, the voltage doubler rectifier converter is smaller and more weighing than a step-up transformer, so that even if it is housed in a headphone housing, the listener will hardly feel any sense of incongruity.

In addition , since a positive polarity voltage having a different polarity is applied to each fixed pole from the positive side voltage doubler rectification unit and the negative side voltage doubler rectification unit, the polarization voltage can be made lower than before.

According to the second aspect of the present invention, the polarization voltage, that is, the headphones, is switched by switching the intermediate tap drawn from the predetermined rectification stage included in the plus side voltage doubler rectifier and the minus voltage doubler rectifier. The output sound pressure (sensitivity) can be adjusted.

According to the third aspect of the present invention, by adjusting the voltage level of the DC low voltage source input by the input voltage adjusting means provided in the input stage of the converter, the headphone of the same as the second aspect is provided. The output sound pressure can be adjusted as appropriate. If the intermediate tap according to claim 2 is a coarse adjustment means, the input voltage adjustment means according to claim 3 is a fine adjustment means. Moreover, since the headphones of the present invention are battery-driven, the power cable can be eliminated from the headphone housing.

  Next, an embodiment of the present invention will be described with reference to FIG. 1, but the present invention is not limited to this. FIG. 1 is a circuit diagram showing a polarization voltage output unit which is a main part of the present invention. The configuration of the headphone housing and the configuration of the electro-acoustic converter housed in the headphone housing are the same as those in FIG. Since they may be the same as the conventional examples described, the same reference numerals are used for these, and detailed description thereof is omitted.

  In FIG. 1, a portion surrounded by a two-dot chain line is the inside of the headphone housing 10. According to the present invention, an electro-acoustic converter (push-pull type) 20 and a polarized voltage output unit 100 that applies a polarized voltage to the fixed poles 23 and 24 are housed in the headphone housing 10.

  As described above, since the high-polarization voltage is generated by the polarization-voltage output unit 100 in the headphone housing 10, the polarization power supply supplied from the outside is, for example, a DC low voltage source 210 of 5V. Good. Therefore, the DC low voltage source 210 may be required for a battery, and in some cases, the battery may be stored in the headphone housing 10.

  In the present invention, a voltage doubler rectifier type converter is used for the polarization voltage output unit 100. In this example, both the positive voltage doubler rectification unit 110 made of a Cockcroft-Walton circuit and the minus voltage are used for the polarization voltage output unit 100. A side voltage doubler rectifier 120 is included.

  In this regard, a sine wave oscillator 130 that outputs a DC voltage supplied from the DC low voltage source 210 as an AC voltage is connected to the voltage input stage of the polarization voltage output unit 100, and a plus-side voltage doubler rectifier unit. 110 applies a double voltage rectification of the positive half-wave of the AC voltage to one fixed pole 23, and a negative-side double voltage rectification unit 120 doubles the negative half-wave of the AC voltage. The polarization voltage thus formed is applied to the other fixed electrode 24. The sine wave oscillator 130 is an oscillator included in the Hartley type, but other types of oscillators may be used.

  In this example, each voltage doubler rectifier 110, 120 is 7 times rectified, and + 300V is obtained by the plus voltage doubler rectifier 110 from the DC 5V voltage supplied from the DC low voltage source 210. 23, −300 V is obtained by the minus-side voltage doubler rectifying unit 120 and applied to the other fixed electrode 24. In this way, by applying a bipolar polarization voltage to the fixed poles 23 and 24, the polarization voltage can be kept low.

  On the other hand, an audio signal is applied from the audio signal source 220 to the diaphragm 21 and the fixed poles 23 and 24 via the audio input unit 221. In this example, unlike the above-described conventional example, the fixed poles 23 and 24 are set to the ground level of the signal voltage. On the other hand, for example, a signal voltage of 100 V (effective value) is applied to the diaphragm 21. Vibrates by push-pull drive.

  The condenser headphone of the present invention includes two means for making it possible to adjust the output sound pressure (sensitivity). As one of them, for example, the first and second intermediate taps T1 and T2 are drawn from a predetermined rectification stage included in the plus side voltage rectifier 110 and the minus side voltage rectifier 120, and this intermediate tap T1. , T2 can be selectively connected to the fixed poles 23, 24 via a changeover switch (not shown).

  In this example, the first intermediate tap T1 is drawn from the third stage, the polarization voltages obtained from the first intermediate tap T1 are + 100V, −100V, the second intermediate tap T2 is drawn from the fifth stage, and the second intermediate tap The polarization voltage obtained from the tap T2 is + 200V, −200V, and the polarization voltage applied to the fixed poles 23, 24 by a changeover switch (not shown) is any of + 300V, −300V; + 200V, −200V; + 100V, −100V. Can be switched.

  Another adjusting means is a variable resistor 131 provided on the input side of the sine wave oscillator 130. If the switching of the polarization voltage by the intermediate tap is a rough adjustment means, the variable resistor 131 is a fine adjustment means that can linearly change the voltage level of the DC voltage supplied from the DC low voltage source 210. .

  Note that the sine wave oscillator 130 is not necessarily provided in the headphone housing 10 and may be included on the DC low voltage source 210 side in some cases. In any case, according to the present invention, since it is not necessary to supply a high polarization voltage to the headphone housing 10 via the power cable, there is no risk of electric shock when using the headphones, and it is safe. Further, since the polarization voltage can be adjusted, the yield when combining the left and right headphone units can be improved.

The circuit diagram which shows the polarization voltage output part which is the principal part of this invention. Sectional drawing which shows the structural example of the conventional push pull type | mold capacitor headphone. The schematic diagram which shows the drive system of the conventional push pull type | mold capacitor headphone.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Headphone housing | casing 20 Electric-acoustic converter 21 Diaphragm 23,24 Fixed pole 100 Polarization voltage output part 110 Positive side voltage doubler rectification part 120 Negative side voltage doubler rectification part 130 Sine wave oscillator 131 Variable resistor 210 DC low voltage Source 220 Audio signal source T1, T2 Middle tap

Claims (3)

A headphone housing in which a push-pull type electro-acoustic converter having a pair of left and right fixed poles disposed on both sides of a diaphragm provided with conductivity via a spacer ring, and the electro-acoustic converter Capacitor headphones comprising a polarization voltage output unit for applying a polarization voltage to a sound signal input unit for inputting a sound signal,
A double voltage rectifier type converter that generates the polarized voltage from a predetermined DC low voltage source is housed in the headphone housing as the polarized voltage output unit . The converter includes a plus side double voltage rectifier unit and a negative voltage rectifier unit. A voltage doubler rectifier, a battery is used as the DC low voltage source, and an oscillator that outputs a DC voltage supplied from the battery as an AC voltage is provided at the input stage of the converter, and the positive side A positive polarization voltage obtained by voltage rectification of the positive half-wave of the AC voltage is applied to the one fixed pole from the voltage doubler rectifier, and the voltage is applied to the other fixed pole from the minus voltage doubler rectifier A negative polarization voltage obtained by double voltage rectification of the negative half-wave of the AC voltage is applied, and the audio signal is transmitted between the diaphragm and each fixed pole from the audio signal input unit. Capacitor headphones, characterized in that it is force. An intermediate tap is drawn from a predetermined rectification stage included in the positive side voltage doubler rectifier and the negative side voltage doubler rectifier, and a polarization voltage can be applied to each fixed pole from the intermediate tap. The capacitor headphone according to claim 1 . 3. The condenser headphone according to claim 1, wherein an input voltage adjusting means for adjusting a voltage level of the DC low voltage source is provided at an input stage of the converter.

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