JP5607999B2 - Headphone unit inspection device - Google Patents

Description

  The present invention relates to a headphone unit inspection apparatus that can inspect the presence or absence of variations in acoustic characteristics without attaching a pair of headphone units constituting a headphone such as stereo headphones to an artificial ear.

  An electrodynamic acoustic transducer has a dynamic impedance due to resonance of a diaphragm, and dynamic headphones as one of such electrodynamic acoustic transducers are designed with a resonant frequency set to a relatively low frequency.

  In this case, the resonance frequency and resonance sharpness of the dynamic headphones greatly depend on the quality of the headphone unit itself, and thus vary greatly. In particular, in stereo headphones, such variations degrade sound image localization and sound quality.

  In general, the left and right headphone units constituting the headphones including such stereo headphones are generally input signals to the respective headphone units, generate sound waves, and measure with the artificial ears for measurement. Often tested for differences.

  On the other hand, since the headphone unit including the dynamic headphone unit is used by being incorporated in stereo headphones that convert electric signals output from the playback device and the receiving device into sound waves through a speaker arranged close to the ear, It is hoped that there will be no variation.

  The measurement of the acoustic performance of the headphone unit performed from such a request is usually performed by using the headphone unit in addition to the headphone unit to be measured during the assembly process arranged in the sound field to be measured with a measurement signal of a predetermined frequency. The sound wave to be output is picked up by a microphone installed at a predetermined position, the output of the detected sound wave is read by a level meter, and the suitability is judged based on the output value displayed on the level meter. It is done by.

  However, such an acoustic performance measurement method is complicated in terms of work because it is necessary to read and visually check the output value displayed on the level meter each time during the assembly process of the headphone unit. There was a problem that it also took.

  Also, the frequency response of each headphone unit is checked by adding a measurement signal to the microphone while sweeping the frequency, and determining the quality of the headphone unit from the output value read as data corresponding to the frequency displayed on the level meter. There was an additional complication that had to be done.

  The present applicant has already proposed a headphone unit inspection method disclosed in Patent Document 1 as a solution to such a problem.

JP 2008-283564 A

  In the headphone unit inspection method disclosed in Patent Document 1, a reference headphone unit having a proper acoustic characteristic and a headphone unit to be measured are arranged with a gap therebetween so that the sound emission parts face each other. In addition to applying a predetermined measurement signal to the reference headphone unit, the same measurement signal is added to the headphone unit to be measured in a phase opposite to that of the reference headphone unit, and the sound waves output from both are supplied to the reference headphone unit and the headphone unit to be measured. Are detected by a microphone arranged between the two, and displayed on an acoustic measurement device to determine whether the headphone unit to be measured is appropriate or not.

  For this reason, according to the headphone unit inspection method of Patent Document 1, when a predetermined measurement signal is applied, the sound wave output from the sound emitting unit of the reference headphone unit and the sound output unit of the headphone unit to be measured are output. The sound waves to be sounded are in opposite phases to each other and synthesized at an intermediate position and collected by the microphone.

  In other words, when there is no difference between the acoustic performance of the reference headphone unit and the acoustic performance of the headphone unit to be measured, the sound waves output from each of the headphone units are the same, and the pressure due to the positive sound waves output to the sound field and the negative sound waves As a result of balancing with the pressure, the atmospheric pressure of the sound field does not substantially change, and the diaphragm inside the microphone does not vibrate, so that no sound component is detected.

  When there is a difference between the acoustic performance of the reference headphone unit and the acoustic performance of the headphone unit to be measured, the diaphragm inside the microphone vibrates and a sound component is detected.

  And, since the sound wave detected can be judged as appropriate by visually observing the shake of the needle displayed on the level meter, without reading the output value even during the assembly process of the headphone unit, It is possible to easily check the variation in acoustic performance.

  However, in the case of using the conventional method of measuring with an artificial ear, depending on how the stereo headphones are attached to the artificial ear, leakage of sound waves from the ear pad may occur or the distance from each headphone unit may vary. As a result, the bass characteristic has changed greatly, making it difficult to measure accurately and requiring careful measurement, resulting in an increase in the time required for measurement.

  Further, in the case of the headphone unit inspection method disclosed in Patent Document 1, there are problems that measurement errors are likely to occur due to ambient noise and the like, and the apparatus configuration for inspection is complicated.

  In view of the above-described problems of the prior art, the present invention is a headphone unit inspection capable of inspecting acoustic performance with less error without being influenced by the surrounding environment under a simple configuration without using an artificial ear. There is an objective to provide a device.

  The present invention has been made to achieve the above object, a pair of fixed resistors having a uniform resistance value arranged to form an AC bridge between a pair of headphone units prepared as inspection targets, The AC galvanometer having a balanced input connected to the detection end of the formed AC bridge and the headphone unit are swept in frequency to make the difference between the dynamic impedances in an acoustically identical state. The main feature is that it is composed of a sine wave transmitter arranged to be detected by an AC galvanometer.

  In this case, the pair of headphone units prepared as inspection targets may be in any state before being assembled as completed headphones or after being assembled.

  According to the first aspect of the present invention, a headphone unit is not attached to an artificial ear, and an AC galvanometer having a balanced input is connected to the detection end of the AC bridge to simply detect a difference in dynamic impedance. Based on the device configuration, it is possible to accurately detect variations in the acoustic performance of the pair of headphone units.

  In addition, according to the invention described in claim 2, it is possible to inspect whether or not there is a variation in acoustic performance after assembling as a completed headphone, as well as a headphone unit having the left and right characteristics even before the assembling. By selecting the, you can also assemble it as a finished headphone with no variation in acoustic performance.

Explanatory drawing which shows an example of this invention apparatus.

  As shown in FIG. 1, the device of the present invention includes a pair of fixed resistors having a uniform resistance value and arranged to form an AC bridge between a pair of headphone units prepared as inspection targets. The AC galvanometer having a balanced input connected to the detection end of the AC bridge and the AC galvanometer by sweeping the frequency while making each of the headphone units acoustically the same state. And a sine wave transmitter arranged to be detected.

This will be described more specifically with reference to FIG. 1. One fixed resistor R _S1 and the other fixed resistor R _S2 having the same resistance value, and a pair of headphone units Z _L and Z _R prepared as inspection targets. An AC bridge is formed between

An AC galvanometer D such as a level meter having a balanced input is connected via the detection terminals t ₁ and t ₂ of the AC bridge formed in this way.

Furthermore, sine wave oscillator O, such as oscillator, the headphone unit Z _L, Z acoustically same state the left and right _R, for example, the headphone unit Z _L, the support such as a desk or the like left and right housings of the headphones incorporating Z _R They are connected and arranged so that the AC galvanometer D can detect the difference in dynamic impedance by sweeping the frequency after placing them on the table and making them acoustically the same. The difference in dynamic impedance generated here is derived from the difference between the resonance frequency and the resonance sharpness.

Next, the operation and effect of the present invention having the above configuration will be described with reference to FIG. 1. In order to form an AC bridge between one fixed resistor R _S1 having the same resistance value and the other fixed resistor R _S2. First, a pair of headphone units Z _L and Z _R prepared as inspection targets are connected.

Next, the operator sweeps the frequency of the sine wave transmitter O after making the left and right of the headphone units Z _L and Z _R acoustically identical.

The operator simply looks at the difference in the dynamic impedance generated when the frequency of the sine wave oscillator O is swept as described above as the fluctuation of the pointer n of the AC galvanometer D, and thus the headphone units Z _L and Z _R. Thus, it can be easily confirmed whether or not there is variation in the acoustic performance.

That is, according to the present invention, the AC galvanometer D having a balanced input at the detection ends t ₁ and t ₂ of the AC bridge can be provided without attaching the headphone units Z _L and Z _R to an artificial ear that tends to cause measurement errors. It is possible to accurately detect variations in the acoustic performance of the pair of headphone units Z _L and Z _R under a simple device configuration in which the difference in dynamic impedance is simply detected by connection.

Further, since the pair of headphone units Z _L and Z _R prepared as inspection targets may be either before or after assembling the headphones, it is inspected whether there is a variation in acoustic performance after assembling the headphones. The headphone units Z _L and Z _R having the same left and right characteristics can be selected before assembling the headphone, so that the headphone unit can be assembled later as a headphone having no variation in acoustic performance.

Further, when a pair of headphone units Z _L and Z _{R included in} the headphone after assembly is to be inspected, a plug provided on the open end of the lead cord of the headphone is connected to one fixed resistor R _S1 . The AC bridge shown in FIG. 1 can be formed simply by being inserted into the socket connected to the other fixed resistor R _S2 , so that each acoustic performance can be easily inspected.

Z _L , Z _R headphone unit R _S1 , R _S2 fixed resistance t ₁ , t ₂ detection end D AC galvanometer n pointer O pointer O sine wave transmitter

Claims (2)

An alternating current having a pair of fixed resistors having a uniform resistance value arranged to form an AC bridge between a pair of headphone units to be inspected and a balanced input connected to the detection end of the formed AC bridge Consists of a galvanometer and a sine wave transmitter arranged to sweep the frequency and cause the AC galvanometer to detect a difference in dynamic impedance while each of the headphone units is in an acoustically identical state A headphone unit inspection device characterized by that. The headphone unit inspection device according to claim 1, wherein the pair of headphone units prepared as inspection targets is in a state before being assembled as completed headphones or after being assembled.

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