JPH0568196

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DESCRIPTION JPH0568196
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
on-vehicle speaker device, and more particularly to a speaker device capable of suppressing
vehicle noise mixed in a radio receiver.
[0002]
2. Description of the Related Art When a user mounts a speaker device in his / her vehicle, the
speaker device is often installed in the rear tray of the vehicle. The reason is that the rear tray is
easy to mount, and the speaker devices mounted on both sides of the rear tray do not obstruct
the driver's view, and a well-balanced stereo effect can be obtained.
[0003]
FIG. 2 is a view showing the positional relationship of the reproduction apparatus mounted on
the vehicle, in which 1 is a vehicle, 2 is a radio receiver attached to the instrument panel of the
vehicle 1, and 10 is a speaker device attached to a rear tray. , 4 is a speaker harness wired
between the radio receiver 2 and the speaker device 10, and 6 is a glass antenna embedded in
the rear window. And 5 is a vehicle harness wired to each electric component of a vehicle, and is
wired with the said speaker harness 4 along the floor part of a vehicle.
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[0004]
As shown in FIG. 3, the speaker unit 10 comprises a speaker unit 13 and a speaker box 12 for
housing the speaker unit 13. Further, on the back of the speaker box 12, a pair of speaker
terminals, ie, positive electrodes The terminal 14 and the negative electrode terminal 15 are
provided.
[0005]
By the way, the running vehicle generates noises from the ignition system, the power generation
and charging system, and various accessory electric component systems, and these noises are
received by the various radio receivers. It is well known to give obstacles.
[0006]
For example, as shown in FIG. 2, when the speaker harness 4 and the vehicle harness 5 are wired
together and the speaker device and the glass antenna 6 are in close proximity to each other,
noise is mixed in the radio. Easy to do.
The noise generated from the vehicle 1 is induced to the vehicle harness 5, and further, the
vehicle harness 5 is induced to the speaker harness 4 as a noise current.
Then, this noise is finally radiated from the speaker device 10 into the air, propagated to the
glass antenna 6 at a close position, and mixed in the reception frequency.
[0007]
When radio reception is performed in such an environment, the degradation in the quality of the
reproduced signal is not avoided, and the installation positional relationship between the speaker
device and the antenna is not limited to the case described above. The same is true for the rod
antenna or for the rear speaker and the rear rod antenna.
[0008]
The present invention has been made in view of the above-mentioned circumstances, and
provides a low-pass filter in a speaker device to suppress noise radiated from the speaker device
and provide an on-vehicle reproducing device capable of reproducing a signal with less noise.
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The purpose is that.
[0009]
SUMMARY OF THE INVENTION In order to achieve the above object, the on-vehicle speaker
device according to the present invention is an on-vehicle speaker installed at a position close to
a radio receiving antenna, the radio receiving device A ground terminal is provided in parallel
with the speaker terminal to which the machine output audio signal is supplied, and a capacitor
forming a part of a low pass filter is connected between the speaker terminal and the ground
terminal. It is formed by the impedance component and the capacitance of the capacitor, and the
cutoff frequency of the low pass filter is set near the radio reception frequency.
[0010]
The capacitor connected between the speaker terminal and the ground terminal forms a low pass
filter circuit with the impedance component of the receiver output circuit.
On the other hand, the noise generated from each part of the running vehicle is guided to the
speaker harness, and is further radiated to the receiving antenna at the close position through
the speaker device.
The cut-off frequency of the low-pass filter is set in advance near the reception frequency, and
noise components of frequencies near the reception frequency among the noise radiated from
the speaker device are suppressed by the low-pass filter, Contamination is prevented.
[0011]
DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with
reference to the drawings.
FIG. 1 is a block diagram of an on-vehicle speaker device according to the present invention. In
the figure, 20 is a speaker box, and 22 is a single speaker unit housed in the speaker box 20. A
pair of speaker connection terminals 23 and 24 is provided on the back of the speaker box 20,
and the speaker harness 4 is wired between the speaker terminals 23 and 24 and the speaker
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output terminals of the receiver 2 shown in FIG. . In the speaker terminals, 23 is a positive
electrode terminal and 24 is a negative electrode terminal.
[0012]
The reference numeral 25 denotes a capacitor which forms a part of the low pass filter of the
present invention, and the reference numeral 26 denotes a ground terminal provided parallel to
the speaker terminals 23 and 24. The capacitor 25 is connected between the speaker terminal 23
and the ground terminal 26, and the ground terminal 26 is usually connected to a metal part
conducting to the chassis of the vehicle.
[0013]
Next, the operation of the present invention will be described. Assuming that the capacity of the
capacitor is C, and the impedance component of the output circuit of the receiver 2 is R, the
cutoff frequency fc of the low-pass filter formed by the capacity of the capacitor and the output
circuit impedance is fc = 1 / 2πCR. However, the impedance component R of the receiver output
circuit is obtained by superimposing the inherent impedance component included in the speaker
harness 4 on the speaker output impedance.
[0014]
Therefore, if the cut-off frequency fc is selected in the vicinity of the reception frequency and the
capacitance C of the capacitor 25 is determined, of the noise radiated into the air from the
speaker unit 22, a noise component which is a frequency near the reception frequency Is
suppressed by the low pass filter. Therefore, even if the speaker device is installed at a position
close to the receiving antenna, noise interference is not given to the receiver, so that high quality
reception can be performed. And, the cutoff frequency fc is the audio frequency reproduced by
the speaker device. Even if the capacitor 25 is connected to the speaker terminal 23, the quality
of the audio signal is not degraded because it is sufficiently higher.
[0015]
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Although the capacitor 25 is connected between the positive terminal 23 and the ground
terminal 26 of the speaker terminals in the above embodiment, the same effect can be obtained
by connecting the capacitor 25 between the negative terminal 24 and the ground terminal. Be
Also, capacitors of the same capacity may be connected between the positive and negative
speaker terminals 23 and 24 and the ground terminal 26, respectively. Further, although the
noise in the positional relationship between the rear glass antenna and the rear speaker has been
described in the embodiment, it is needless to say that the noise suppression effect can be
obtained by the low pass filter also in the case of the front speaker and the pillar antenna.
[0016]
As described above, according to the on-vehicle speaker device of the present invention, the
ground terminal is provided in parallel with the speaker terminal, and a low pass filter is formed
between the speaker terminal and the ground terminal. Since the capacitor is connected and the
cutoff frequency of the low-pass filter is set close to the reception frequency, the reception
frequency of the noise generated from the traveling vehicle and guided to the speaker harness
and propagated from the speaker device to the air The noise components of nearby frequencies
are suppressed by the low-pass filter, so that noise mixing into the receiver via the antenna
located close to the speaker device is prevented, and the receiver always performs high-quality
reception it can.
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