JP2003250190

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DESCRIPTION JP2003250190
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
headphone device for portable equipment such as portable audio equipment.
[0002]
2. Description of the Related Art In a conventional portable audio apparatus, one of the wires is
soldered to the terminal of a headphone speaker using a flexible metal wire such as a litz wire,
and the other is used as a connector. It was connected to the plug.
[0003]
The headphone device of this type of conventional portable device can not ignore the contact
resistance of the connector because the impedance of the speaker is low.
The maximum value is about 10 mΩ in consideration of variations in contact pressure and the
like. When the impedance of the speaker is about 16 Ω, this has a value of -64 dB, and the
change in the contact resistance due to the vibration appears as noise, and the change due to the
signal current appears as distortion in voice.
[0004]
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Even if the main body side has distortion and noise performance of about -100 dB, it will be
extremely deteriorated in the headphone drive section. Then, an object of this invention is to
reduce the influence of the contact resistance by a connector, and to provide a headphone
apparatus excellent in distortion and a noise characteristic.
[0005]
[Means for Solving the Problems] In order to achieve the above object, in the present invention, a
headphone cable for connecting a plug connected to a portable device and a headphone unit is
constituted by a light transmission means, and in the plug A device for converting an analog
audio signal from the device to a pulsed analog electrical signal and an electro-optical (E / O)
converter for converting the pulsed analog electrical signal to a light signal are provided, and the
headphone unit is provided with a light transmitting device. Means for driving the speaker based
on the signal from the photoelectric (O / E) conversion means, the speaker, and the photoelectric
(O / E) conversion means for converting the light signal from As a headphone device for portable
equipment equipped with Thus, by interposing the light transmitting means, the circuit
impedance of the contact portion of the plug can be increased, so that the influence of the
contact resistance by the connector can be reduced, and the generation of noise and distortion
due to the contact resistance can be suppressed.
[0006]
In addition, a headphone cable for connecting a plug connected to a portable device and a
headphone unit is constituted by light transmitting means, and an electric light (E / A) for
converting a pulsed analog electric signal from the device into an optical signal is contained in
the plug. O) A conversion means is provided, and the headphone unit is provided with a signal
from a photoelectric (O / E) conversion means, a speaker, and the photoelectric (O / E)
conversion means for converting an optical signal from the light transmission means into an
electric signal. According to the headphone device of a portable device equipped with a means
for driving a speaker and a battery for supplying power to the headphone unit, the device has a
means for converting an analog audio signal into a pulsed analog electrical signal. Since the
circuit impedance of the contact portion of the plug can be increased by interposing the light
transmission means, the influence of the contact resistance by the connector can be Hesi it is
possible to suppress the generation of noise or distortion due to contact resistance.
[0007]
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Further, if the headphone device of the portable device is a circuit for operating the speaker in
the D class, the speaker driving unit can be operated in the D class, and therefore the power
consumption can be reduced.
[0008]
In addition, if the headphone unit has a means for detecting a direct current component of a
signal from the photoelectric conversion means and turning on / off a path for supplying power
from the battery, the headphone device automatically It can manage the on / off of the switch
and can be a headphone device of a portable device that is easy to handle.
[0009]
Further, the interval between the free run frequency for the left channel and the free run
frequency for the right channel of the means for converting the analog audio signal into a pulsed
analog electrical signal is taken wider than 1/2 of the sum of the bandwidths of the sidebands.
The headphone device of the portable device can reduce the interference of the left and right
channels.
[0010]
In addition, if a litz wire is further inserted into the protective mold of the headphone cable and
the headphone device of a portable device for charging the battery by the power supply from the
litz wire is used, the battery charging operation and the charging device can be simplified. it can.
[0011]
Further, a headphone cable for connecting a plug connected to a portable device and a
headphone unit is constituted by a light transmitting means, and a means for converting an
analog audio signal from the portable device into a pulsed analog electric signal in the plug And
an electro-optical (E / O) conversion means for converting the pulsed analog electric signal into
an optical signal, and the headphone section comprises a photoelectric (O / E) conversion for
converting an optical signal from the optical transmission means into an electric signal Means, a
speaker, and means for driving the speaker based on a signal from the photoelectric (O / E)
conversion means, and further inserting a litz wire into the protective mold of the headphone
cable, the headphone from the litz wire If the headphone device of the portable device is
operated to operate the circuit of the headphone unit by the power supply to the unit, the battery
on the headphone unit side is eliminated. , It can further reduce the size of the headphone unit.
[0012]
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In addition, a headphone cable for connecting a plug connected to a portable device and a
headphone unit is constituted by a light transmitting means, and an electric light for converting a
pulsed analog electric signal from the portable device into an optical signal is included in the
plug (E (E) / O) A conversion means is provided, and the headphone unit is provided with a
photoelectric (O / E) conversion means, a speaker, and a signal from the photoelectric (O / E)
conversion means for converting an optical signal from the light transmission means into an
electric signal. Means for driving a speaker based on the above, and further inserting a litz wire
into the protective mold of the headphone cable, and operating the circuit of the headphone unit
by supplying power from the litz wire to the headphone unit. If the headphone device of the
device is used, the battery on the headphone unit side can be eliminated and the headphone unit
can be further miniaturized.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be
described with reference to the drawings.
[0014]
1 to 6 show a first embodiment according to the present invention.
FIG. 1 is an external view showing the entire headphone device of a portable device.
FIG. 2 is a block diagram of a circuit incorporated in the plug of the headphone device of FIG.
FIG. 3 is a block diagram of a circuit incorporated in the headphone unit of the headphone device
of FIG.
FIG. 4 is an explanatory view showing an arrangement example of components of the plug of the
headphone device of FIG.
FIG. 5 is an explanatory view showing an arrangement example of components of the headphone
unit of the headphone device of FIG.
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FIG. 6 is a spectrum diagram showing frequency spectra of two PWM (Pulse Width Modulation)
circuits incorporated in the plug of the headphone device of FIG.
[0015]
The headphone device 1 of the portable device shown in FIG. 1 is connected to a portable device
main body (not shown) such as an audio device by a plug 2, here a mini jack, and is connected to
the headphone cable 3; The headphones 5L and 5R of L (left) and R (right) of the headphone unit
5 are connected by two POF (plastic optical fiber) cables 3L and 3R for the channel) and R
channel (right channel), respectively.
[0016]
The circuit shown in FIG. 2 is mounted on the plug 2, and the arrangement structure is as shown
in FIG. 4, for example.
Analog audio signals of the left channel (Lch) and right channel (Rch) are converted to pulsed
analog signals by PWM (pulse width modulation) circuits 21L and 21R, respectively, and optical
signals are converted by E / O (electro-optical conversion) circuits 22L and 22R. , And
transmitted by the POF cables 3L and 3R, respectively.
In FIG. 4, the plug 2 is composed of a jack portion 2a and a grip portion 2b thereof, and terminal
contacts are arranged in the jack portion 2a as in the known art.
In the grip portion 2b, the PWM circuits 21L and 21R for the left channel (Lch) and the right
channel (Rch) and the E / O circuits 22L and 22R are disposed on the front and back of the
substrate 23 in the inside thereof for necessary connection Is stored. The optical signals from the
E / O circuits 22L and 22R are transmitted to the headphone unit 5 by the POF cable 3 extending
from the end of the grip 2b.
[0017]
The circuit shown in FIG. 3 is mounted on the headphones 5L and 5R of L and R of the
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headphone unit 5, and the arrangement structure thereof is, for example, shown in FIG. 5 (only
the headphone 5L is shown. As shown in). The optical signal from the POF cable 3L is converted
into an electric signal by the O / E conversion circuit 51L, and the electric power necessary to
drive the left speaker 54L is amplified by the driver 52L which is a driving means. Battery 56L
(This may be a normal button type battery or a storage battery. ) Is incorporated in the housing
5LB of the headphone 5L, and power is supplied to the circuit via the SW (switch) 55L that is
turned on / off by the presence or absence of the DC component D of the O / E conversion circuit
51L. . The driver 52L amplifies the PWM signal as it is in order to suppress heat generation, and
the final stage performs D class operation. Since the driver 52L for driving the speaker can be
operated in the D class, power consumption can be reduced.
[0018]
The PWM signal, which is the output from the driver 52L, has its high frequency component
attenuated by a simple LPF (low pass filter) 53L, and the obtained audio signal is supplied to the
speaker 54L. Although the above relates to the driving of the left speaker 54L, the right speaker
54R (not shown). The circuit configuration is the same for.
[0019]
As shown in FIG. 5, in the headphone 5L, the components of the circuit shown in FIG. 3 and the
components of the speaker 54L are disposed in the housing 5LB. At the center of the housing
5LB, a speaker 54L is disposed centering on the core 54LC of the speaker. A fan-shaped
substrate 57 is disposed at the periphery thereof. On the substrate 57, the O / E conversion
circuit 51L is located opposite to the end of the POF cable 3L on the left, the driver 52L and SW
(switch) 55L near the center of the substrate 57, and on the right of the substrate 57 in the
figure. A battery 56L is disposed and connected by a wire (not shown) on the substrate according
to the circuit diagram of FIG. 3 and is connected to the terminal 54LT of the speaker.
[0020]
If the PWM (Pulse Width Modulation) circuits 21L and 21R of the left channel (Lch) and the right
channel (Rch) are different from each other as shown in the spectrum diagram of FIG. I'm sorry.
The spacing between the two free run frequencies is wider than the sum of the bandwidths of the
sidebands S1 and S2 so that the occupied frequency bands do not interfere with each other.
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[0021]
Here, the input impedance of the PWM circuit of the left channel (Lch) and the right channel
(Rch) in FIG. 2 is several 10 kΩ or more, and the contact resistance of the contact portion of the
terminal of the plug (mini jack) 2 is as low as 10 mΩ. The impact is negligible.
[0022]
FIG. 7 is a block diagram of a circuit incorporated in the plug 2 of the headphone device of the
portable device according to the second embodiment of the present invention.
Unlike FIG. 2, the left channel (Lch) and right channel (Rch) inputs have already been made into a
pulsed analog signal on the device body side, so that no PWM (Pulse Width Modulation) circuit is
required for each channel It becomes. The left channel and right channel E / O (electro-optical
conversion) circuits 122L and 122R and the POF cables 103L and 103R respectively connected
thereto are the same as those in FIG.
[0023]
FIG. 8 is a partial cross-sectional perspective view showing an example of a headphone cable
used in a headphone device of a portable device according to a third embodiment of the present
invention. A POF (plastic optical fiber) cable 203 has a litz wire 206, 206 molded in a protective
mold 207 covering the periphery of the POF (plastic optical fiber) 204. This litz wire is used here
for power supply.
[0024]
FIG. 9 is a block diagram of an entire circuit in a headphone device as a third embodiment using
the headphone cable (POF cable with litz wire) 203 of FIG. In FIG. 9, the same components as
those of the first embodiment shown in FIGS. 1 to 6 are denoted by the same reference numerals.
The headphone cable 203 is disassembled into a POF and a litz wire, and L and R on the left and
right are added to the reference numerals in FIG. The litz wire 206 is used here to supply power
to the headphone unit 5 side.
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[0025]
Capacitors 60 and 61 are provided to reduce fluctuations in the supplied power.
[0026]
FIG. 10 is a circuit diagram showing an additional circuit in the case where an internal battery is
attached to the headphone unit 5 side of the circuit of the third embodiment in FIG.
The terminals K1 and K2 of FIG. 10 are connected to a point K of FIG. 9, and the terminals M1
and M2 of FIG. 10 are connected to a point M of FIG. The positive terminal of the battery 56 is
connected via the terminal K1 and the diode 58, and the negative terminal of the battery 56 is
connected via the terminal M1 and the diode 59, respectively. The battery 56 on the headphone
unit 5 side is charged by the litz wire 206.
[0027]
As described above, according to the present invention, the electro-optical conversion unit is
provided on the plug side of the headphone device of the portable device, and the photoelectric
conversion unit is provided on the headphone unit side to light the pulsed analog signal. The
transmission means transmits from the plug side to the headphone unit side, so that the
influence of the contact resistance due to the connector can be reduced, and a headphone device
of a portable device with good distortion and noise characteristics can be obtained.
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