JP6802954B2 - Wiring structure of digital drive type electroacoustic converter and digital drive type headphones - Google Patents

Description

The present invention relates to a wiring structure of a digitally driven electroacoustic converter and digitally driven headphones.

Conventional headphones use an analog signal as an input signal and drive a diaphragm according to the strength and frequency of the analog signal to output sound waves. Therefore, even if the signal from the sound source device is a digital signal, a "digital-analog converter" is placed between the sound source device and the headphones to convert it to an analog signal and then input it to the electroacoustic converter. I needed it.

In recent years, instead of converting a digital signal from a sound source device into an analog signal, the digital signal can be input to an electroacoustic converter as it is, and a vibrating plate can be driven according to the density of the digital signal to output sound waves. Digital-to-analog converters have been developed to enable this. (See, for example, Patent Document 1).

Japanese Patent No. 4883428

By incorporating an electroacoustic converter that applies a digital-to-analog converter as described above into the left and right earpieces, it is possible to configure headphones that convert everything from the sound source to the drive unit into digital signals.

The signal from the sound source is digitally input to one of the electroacoustic converters incorporated in the pair of left and right earpieces via the signal converter, and between the electroacoustic converter and the other electroacoustic converter. Headphones are known in which signals are input via arranged signal lines. The signal line connecting the electroacoustic converters is a connection cable called a "crossover cable". The crossover cable is mainly arranged inside the headband or along the headband.

In general, even if external noise is mixed in the middle of transmission of a digital signal via a signal line, it is easy to eliminate the influence by performing signal correction processing at the transmission destination (receiver). Here, examples of the cause of external noise include electromagnetic waves reaching the signal line from the outside. Since the crossover cable in the headphones passes through the upper part of the head of the user who wears the headphones, it is in a position where it is susceptible to electromagnetic waves from the outside, and the above-mentioned external noise is likely to be mixed.

When headphones configured by applying a signal conversion device as described in Patent Document 1, the signal transmitted by the crossing cable is a digital signal that has been signal-converted to drive the diaphragm. In this case, since the diaphragm is directly driven by the transmitted digital signal, the signal correction process is not performed on the headphones that are the transmission destination.

Driving the diaphragm with a digital signal that is not subjected to signal correction processing at the transmission destination means that the diaphragm is driven by a digital signal containing noise mixed from the crossover cable. Then, the sound wave is output based on the digital signal in which the noise is mixed, without eliminating the influence of the external noise mixed in the middle of the signal line (in the middle of transmission). In this way, even when the diaphragm is directly driven to output sound waves using a digital signal that is said to have high noise immunity, it is affected by external noise and "sound quality (sound quality)". May decrease. The problem of such digitally driven headphones is different from the conventionally known problem of "preventing the mixing of external noise. Eliminating external noise", and a solution to this problem is known. Not.

In order to solve the above problems, a signal conversion device may be arranged in the immediate vicinity of each of the left and right diaphragms. However, such a method has a problem that the cost increases and the structure becomes complicated, for example, a circuit for signal processing is required for each of the left and right signal conversion devices.

Further, the sound wave output from one electroacoustic converter corresponds to a digital signal containing no noise, and the sound wave output from the other acoustic converter corresponds to a digital signal containing noise. It will be according to. Then, in the pair of left and right electroacoustic converters, there may be a difference in sensitivity and sound quality between the output sound from the electroacoustic converter on the left side and the output sound from the electroacoustic converter on the right side.

In addition, since the digital signal contains a large amount of high-frequency components, there is a possibility that a very large amount of unwanted radiation may be generated from the crossover cable to the outside.

The present invention provides a digital drive type electroacoustic converter connection structure and digital drive type headphones that can prevent the entry of external noise into the crossing cable used between the pair of left and right electroacoustic converters and output high-quality sound waves. The purpose is to provide.

The present invention
It is a connection structure of a digital drive type electroacoustic converter having a signal conversion unit that drives a diaphragm with a digital signal and converts it into sound waves.
In the digital drive type electroacoustic converter composed of a pair of left and right, one digital drive type electroacoustic converter connected to the sound source of the digital signal via the first signal line, and one digital drive type electric The other digitally driven electroacoustic transducer connected to the acoustic transducer is connected via a second signal line.
The most main feature of the second signal line is that it has a stranded wire structure in which a positive electrode input line and a negative electrode input line are paired.

According to the present invention, it is possible to prevent external noise from entering the crossover cable used in a pair of left and right electroacoustic converters in which the diaphragm is driven by a digital system, and to output high-quality sound waves.

It is a perspective view which shows the appearance of the Example of the digital drive type electroacoustic converter which concerns on this invention. It is a perspective view which shows the part of the inside of the said Example enlarged. It is a perspective view which shows the vicinity of the end part of the connection structure in the said Example in an enlarged manner. It is a functional block diagram of the said Example. It is another embodiment of the digital drive type electroacoustic converter according to the present invention, and is an enlarged perspective view showing the vicinity of the end portion of the connection structure.

Hereinafter, the wiring structure of the digital drive type electroacoustic converter and the embodiment of the digital drive type headphones according to the present invention will be described with reference to the drawings.

● Electroacoustic converter First, an example of an electroacoustic converter will be described. As shown in FIG. 1, the headphone 100 includes a pair of left and right headphone units 101, which are earpieces in which an electroacoustic converter is incorporated. Each of the headphone units 101 is held by support members 20 connected to both ends of the head pad 30. The headphone unit 101 includes an ear pad 41 that comes into contact with the periphery of the user's ear, and a housing 40 to which the ear pad 41 is attached. The outer shape of the contact surface of the ear pad 41 is substantially oval so as to cover the circumference of the user's ear. The outer shape of the housing 40 also has a substantially oval shape following the ear pads 41. The shapes of the housing 40 and the ear pads 41 are not limited to the substantially oval shape described above. These shapes may be substantially circular or polygonal, which have been conventionally used.

Inside the housing 40, an electroacoustic conversion mechanism that converts an electric signal into a sound wave is arranged. The electroacoustic conversion mechanism includes a voice coil to which a digital signal is applied as an input signal, and a diaphragm that vibrates in response to the digital signal applied to the voice coil and outputs a sound wave. The electroacoustic conversion mechanism also has a magnetic circuit that includes a magnetic gap. The voice coil is located within the magnetic gap. The support member 20 holding the housing 40 is attached to the outside of the housing 40 and is connected in the longitudinal direction of the head pad 30. The support member 20 has a vertically elongated shape that tapers toward the tip in the longitudinal direction.

The digital signal applied to the voice coil is a digital signal obtained by subjecting a digital signal output from a normal sound source device to a predetermined modulation process (signal conversion process). Even if the digital signal output from the sound source device is a PCM signal, the digital signal applied to the diaphragm in the electroacoustic conversion mechanism does not have the same signal format. For example, a pulse density modulation (PDM) signal. Hereinafter, the digital signal applied to the diaphragm is the same.

An internal space is formed in the support member 20, and a signal processing circuit 21 (see FIG. 4) described later is housed in the support member 20. The signal processing circuit 21 is housed only in the internal space of one support member 20 of the pair of left and right housings 40. At the lower end of the support member 20 in which the signal processing circuit 21 is housed, an interface to which the first signal line (connection cable 51), which is a signal input line from the sound source, is connected is provided. The connection cable 51 is used as the first signal line.

The left and right support members 20 that hold the left and right housings 40 are connected to each other via a head pad 30. Further, the left and right support members 20 are connected via a curved bar 10 having a spring property. Both ends of the curved bar 10 are attached to the upper end portion on the front side and the upper end portion on the rear side of the support member 20. The curved bar 10 applies lateral pressure when using the headphones 100. The curved bar 10 also has a function as a headband. The curved bar 10 in this embodiment houses a second signal line, which will be described later. Further, instead of the curved bar 10, the head pad 30 may be configured to have a spring property to give a lateral pressure. In such a configuration, the head pad 30 also has a function as a head band.

● Configuration of Headphone Unit Here, the structure of the headphone unit 101 included in the headphone 100 will be described. As shown in FIG. 4, the headphone unit 101 includes a signal processing circuit 21 and a drive unit 401. The drive unit 401 is an electroacoustic converter that directly converts a digital signal supplied from the signal processing circuit 21 into sound waves and outputs sound.

The drive unit 401 includes a magnetic circuit including a magnetic gap, a voice coil arranged in the magnetic gap, and a diaphragm that vibrates in response to the applied electric signal when an electric signal is applied to the voice coil. Have. By the vibration of this diaphragm, an electric signal is converted into a sound wave and output. As described above, the signal applied to the drive unit 401 is, for example, a digital signal by pulse density modulation, and each drive unit 401 has a plurality of voice coils for one diaphragm.

The signal processing circuit 21 is connected to the sound source device 50, which is a digital sound source, via the connection cable 51, which is the first signal line.

The drive unit 401 on the side where the signal processing circuit 21 is arranged is electrically connected to the signal processing circuit 21 via the signal cable 404. The drive unit 401 on the side where the signal processing circuit 21 is not arranged is electrically connected to the signal processing circuit 21 via a crossing cable 11 which is a second signal line.

The drive unit 401 includes, for example, four voice coils, which are attached to one diaphragm. A digital signal processed by the signal processing circuit 21 is individually applied to each voice coil. Two signal lines are required for each voice coil to connect the signal processing circuit 21 and each voice coil. One is the positive electrode input line and the other is the negative electrode input line. The positive electrode input line and the negative electrode input line form a pair to form a signal cable 404 and a crossover cable 11 for one voice coil.

● Wiring Structure Next, an embodiment of the wiring structure according to the present invention will be described. FIG. 2 is an enlarged view showing an example of a state in which the outer cover of the support member 20 and the housing 40 are removed from one headphone unit 101. As shown in FIG. 2, the signal processing circuit 21 is housed inside the support member 20. The signal processing circuit 21 includes a signal conversion unit, a storage unit in which a signal conversion program is stored, and a cable socket 22 which is an output terminal of a digital signal converted in the signal conversion unit. The signal processing circuit 21 has a shape that tapers downward, similar to the outer shape of the support member 20. The shape of the signal processing circuit 21 is not limited to this.

The signal conversion unit and the signal conversion program execute a predetermined signal conversion process, for example, a process of converting the digital signal input from the sound source device 50 into a signal corresponding to pulse density modulation or the like. The signal conversion process is performed by the signal conversion unit and the signal conversion program, and the generated digital signal is transmitted to the other drive unit 401 via the crossover cable 11 connected to the cable socket 22. The transmitted digital signal is individually applied to each of the plurality of voice coils included in the drive unit 401.

The crossover cable 11 is configured by a stranded wire structure in which a positive electrode input wire and a negative electrode input wire are twisted as a pair. As described above, since the drive unit 401 includes four voice coils, four crossover cables 11 which are stranded wires are required. As shown in FIG. 2, in the crossover cable 11, for example, cable plugs 12 are attached to every two pairs, and the cable plugs 12 are fitted into the cable socket 22 to be connected. The other end of the crossover cable 11 is connected to the lead wire of the voice coil. As a result, the other drive unit 401 is connected to the signal processing circuit 21 arranged on the one drive unit 401 side.

FIG. 3 is an enlarged perspective view of a portion of the region A shown in FIG. As shown in FIG. 3, the crossover cable 11 is arranged inside the curved bar 10 by coating the spring material 13 constituting the curved bar 10. Two pairs of crossover cables 11 are arranged inside one curved bar 10. This is due to the thickness of the curved bar 10, and if a curved bar 10 having a larger diameter is used, four pairs of crossover cables 11 can be arranged inside one curved bar 10. .. Further, the crossover cable 11 may be arranged inside the head pad 30.

The end of the spring member 13 is bent in an L shape in the radial direction of the curved bar 10. The L-shaped end is fitted to the upper end of the support member 20, and the curved bar 10 is attached to the support member 20.

● Effect of connection structure The signal transmitted from the signal processing circuit 21 to the drive unit 401 is a signal that has undergone digital modulation processing to directly drive the diaphragm. Since this digital signal is applied to the diaphragm as a series of digital signals that are square waves and directly vibrates the diaphragm to output sound waves, signal correction processing is not performed. Therefore, if external noise is mixed into the digital signal during transmission, the mixed noise causes a difference in the signal pattern that is originally transmitted, and it is not possible to output sound waves that faithfully correspond to the signal from the sound source device, and the output sound It will reduce the quality.

By using a connection structure having a stranded wire structure in which a positive electrode input wire and a negative electrode input wire are twisted as a pair as in the crossover cable 11 described above, the influence of external noise as described above can be eliminated. Since the codes of the digital signal flowing through the positive electrode input line and the digital signal flowing through the negative electrode input line are inverted, the line coupling property is improved by twisting the positive electrode input line and the negative electrode input line as a pair. As a result, the resistance to external noise can be improved, and the influence of noise of the input digital signal on a specific voice coil can be suppressed.

Further, by twisting the positive electrode input line and the negative electrode input line as a pair to improve the interline coupling property, it is possible to suppress unnecessary radiation from the crossover cable 11 even if a digital signal containing a large amount of harmonic components is passed. it can.

If it is an electro-acoustic converter that uses a connection structure that can eliminate the influence of external noise as described above, the sound quality and sensitivity can be improved even with a full digital configuration without converting the digital signal from the digital sound source to analog. It is possible to maintain a high-quality sound output without degrading it.

● Electromagnetic shield structure having a connection structure The crossover cable 11 may be coated with an electromagnetic shield 14 in which a pair of stranded wires are bundled as shown in FIG. Further, the coating may be performed by using an electromagnetic shield structure in which two or four pairs of stranded wire structures attached to one cable socket 22 are put together. Further, the curved bar 10 may have an electromagnetic shield structure. In these electromagnetic shields, one end thereof is connected to a reference voltage (GND voltage). It is desirable that the connection point to this reference voltage be connected on the side where the signal processing circuit is located.

The above-mentioned shield structure may be configured by using a net-like member having electromagnetic shielding characteristics. Moreover, you may use a conductive tube.

By providing the crossover cable 11 with an electromagnetic shield structure, the resistance to external noise can be further improved. In addition, such an electromagnetic shield structure also has an effect of suppressing unnecessary radiation to the outside.

10 Curved bar 11 Crossover cable 21 Signal processing circuit 40 Housing 51 Connection cable 100 Headphones 101 Headphones unit 401 Drive unit

Claims (8)

It is a connection structure of a digital drive type electroacoustic converter having a signal conversion unit that drives a diaphragm with a digital signal and converts it into sound waves.
In the digital drive type electroacoustic converter composed of a pair of left and right, one digital drive type electroacoustic converter connected to the sound source of the digital signal via the first signal line, and one digital drive type electric The other digitally driven electroacoustic transducer connected to the acoustic transducer is connected via a second signal line.
The second signal line has a stranded wire structure in which a positive electrode input line and a negative electrode input line are paired.
The wiring structure of the digitally driven electroacoustic converter is characterized by this. Each of the digitally driven electroacoustic converters has a plurality of voice coils.
The second signal line is a pair of a positive electrode input line and a negative electrode input line to each of the voice coils of the other digitally driven electroacoustic converter.
The wiring structure of the digitally driven electroacoustic converter according to claim 1. The second signal line includes an electromagnetic shield structure that covers the positive electrode input line and the negative electrode input line in a pair.
The wiring structure of the digitally driven electroacoustic converter according to claim 1 or 2. The second signal line includes an electromagnetic shield structure that individually covers the positive electrode input line and the negative electrode input line.
The wiring structure of the digitally driven electroacoustic converter according to claim 1 or 2. The electromagnetic shield structure is made of a mesh member.
The wiring structure of the digitally driven electroacoustic converter according to claim 3 or 4. The shield structure is made of a conductive tube.
The wiring structure of the digitally driven electroacoustic converter according to claim 3 or 4. A pair of left and right earpieces with a digitally driven electroacoustic converter built into the housing,
A headband that is curved in the longitudinal direction and has the earpieces at both ends,
A headphone having a wiring structure for connecting the digitally driven electroacoustic converter incorporated in each of the earpieces along the headband.
The connection structure is the connection structure of the digitally driven electroacoustic converter according to any one of claims 1 to 6.
Digitally driven headphones that feature this. The connection structure is arranged along the headband,
The digital drive type headphone according to claim 7.

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