JPH0354448Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a power supply circuit for a vehicle audio device, and particularly to a circuit that takes into consideration the suppression of noise generation in the audio device.

[Conventional technology]

Conventionally, for example, as shown in FIG.
and the alternator 2 to connect the vehicle's power supply circuit 3.
, and various electric loads 6, including a sound device 5, are connected to the power supply circuit 3 of this vehicle via a key switch 4.
8 is connected, and there is also an electric load 7 that is connected in parallel to the electric loads 6 and 8 without using the key switch 4. Here, each electric load 6, 7, 8
For example, 6 is a direction indicator via a direction indicator switch 61, 7 is a brake light via a brake light switch 71, and 8 is an engine starter.

The contacts 40 of the key switch 4 are configured to contact contacts 43 and 44 when the engine is stopped, contact contacts 42 and 43 when the engine is running, and contact contacts 41 and 42 when the engine is started.

[The problem that the idea attempts to solve]

However, in a vehicle having a circuit as shown in FIG. Since the noise current containing the noise current flows into the circuit of the audio device 5 through each contact of the key switch 4, noise is generated in the audio device 5.
In particular, the audio frequency (approximately 20 Hz to 20,000 Hz), which is the processing frequency of the main amplifier of the audio device 5, is different from the frequency of the noise current (for example, the ripple included in the output current of an alternator is generally approximately 1 KHz to 20,000 Hz).
10 KHz), the noise current flowing into this main amplifier had a great influence on noise generation in the audio device 5.

Note that the high frequency amplification circuit of the acoustic device 5 that processes the received radio waves from the antenna has a processing frequency (generally 520KHz to 1630KHz and 76MHz to 90M
Hz) is much larger than the frequency of the noise current, so there is little influence on noise generation. As a result,
I was unable to comfortably listen to radio broadcasts, cassette stereo performances, etc. This is because the alternator 2, etc., which are the various noise sources mentioned above, and the acoustic device 5 are arranged in close proximity, so the length of the circuit wires that continue them is shortened, and the noise current generated from the noise sources mentioned above is reduced. The length of the circuit wire from the noise source to the battery 1, which has the function of absorbing these noise currents, is such that it is not sufficiently attenuated before reaching the acoustic device 5.
The reason for this is that the length of the circuit wire is longer than that of the previous circuit.

Note that in order to suppress noise generation in the audio device 5, it has been considered to connect a filter for removing AC components to the power source side of the audio device 5, but in recent years, vehicle audio devices have been developed to improve marketability. As a result, noise suppression filters have to have a large current capacity, making them extremely large, occupying a large space in the audio equipment, and increasing the amount of noise around the vehicle instrument panel. It was becoming difficult to install audio equipment to the

Therefore, in order to fit within a limited space, the performance of the filter naturally has its limits, making it impossible to obtain an audio device that satisfies vehicle occupants who desire high-quality sound with little noise.

Therefore, the object of this invention is to separate the power supply circuit of the audio device from other electrical load circuits, suppress the noise current flowing into the power supply circuit of the audio device, and obtain an audio device with less noise.

[Means to solve the problem]

Therefore, this invention provides a vehicle audio circuit having an audio device connected to the vehicle's power supply circuit including a battery and an alternator connected in parallel via a key switch and an audio device switch, in which at least the main amplifier of the audio device is connected. The power supply circuit is directly connected to the battery of the vehicle power supply circuit through an auxiliary switch that is opened and closed in conjunction with the key switch and the sound device switch, and is isolated from other electrical load circuits.

[Effect]

According to the above-mentioned means, the noise current flowing into the main amplifier side of the audio device is absorbed by the battery, which is equivalent to a capacitor that functions as a filter for noise current absorption, or is sufficiently attenuated in the circuit, so that the noise is reduced. A voltage with few components can be supplied to the audio device, and the generation of noise in the audio device can be suppressed.

〔Example〕

Hereinafter, embodiments of this invention will be described based on the accompanying drawings.

FIG. 2 is a power supply circuit diagram of a vehicle audio device showing an embodiment of this invention.

In the embodiment shown in FIG. 2, the same reference numerals as in FIG. 1 are used for the parts corresponding to those in FIG. 1 described above, and detailed explanation thereof will be omitted.

As shown in FIG. 2, the battery 1 and alternator 2 are connected in parallel to form a vehicle power supply circuit 3.
A relay 50, which is an auxiliary switch, is connected to the power supply circuit 3 of this vehicle through the simplified contacts 43 of the key switch 4, a fuse, a switch coil 57 which is a filter, and a radio switch 51 which is a switch for an audio device. The coil 52 is connected to constitute a first power supply circuit 510 of the radio 5, which is an audio device. The main amplifier 54 of the radio 5, which is an audio device, is directly connected to the battery 1 of the power supply circuit 3 of the vehicle via a relay switch 53, which is closed when the coil 52 of the relay 50 is energized, a choke coil 56, which is a filter, and a fuse. connected to the second power supply circuit 5 of the radio 5
The second power supply circuit 520 is connected to the vehicle power supply circuit 3 as close to the battery 1 as possible. Furthermore, the vehicle power supply circuit 3 of the second power supply circuit 520 of this radio 5
No other electrical load is connected between the connection position and the filter 56, which is the power source side of the radio 5, and is isolated from other electrical load circuits.

A capacitor 58 forming a filter is connected to ground on the side of the main amplifier 54 of the chiyoke coil 56, and a high frequency amplification circuit 55 of the radio 5 is connected in parallel with the relay coil 52. Further, in FIG. 2, the other electrical loads 6, 7, and 8 shown in FIG. The brake light 7 is connected to a circuit from the power supply circuit 3 of the vehicle to the key switch 4.

With this circuit configuration, when both the key switch 4 and the radio switch 51 are turned on, the high frequency amplification circuit 55 is energized, and the relay coil 52 is energized to turn on the relay switch 53. main amplifier 5
Since radio 4 is also energized, radio 5 is activated. Furthermore, if either the key switch 4 or the radio switch 51 is turned on, neither the high frequency amplification circuit 55 nor the main amplifier 54 will be energized, so the operation of the radio 5 will be stopped.

Further, according to this circuit, the power supply circuit 520 of the main amplifier 54 is directly connected to the radio 5 in the vicinity of the battery 1, and is separated from other electrical load circuits without connecting any other electrical load. So,
The ripple of the alternator 2 and the noise current generated in other electrical loads are absorbed by the battery 1, which is equivalent to a capacitor that functions as a filter for absorbing noise current, or are attenuated in the circuit, and the main power of the radio 5 is Almost no current flows into the choke coil 56 on the power supply side of the amplifier 54.

As a result, the noise of the radio 5 can be reduced, and if the noise level of the radio 5 can be tolerated at the conventional level, the inductance of the chiyoke coil 5 that constitutes the filter can be reduced, so that its external shape can be reduced. can be downsized. Therefore, there is no need to limit the outer shape of the filter due to installation in a limited space, so the current capacity of the filter is not limited, making it possible to increase the capacity of the acoustic device.

On the other hand, in the circuit of the contact 43 of the key switch 4,
Although a noise current containing an alternating current component flows in as in the conventional case, since this circuit and the circuit of the main amplifier 54 are separated by the relay 50, no noise current flows into the main amplifier 54.

Furthermore, a noise current tends to flow through the high frequency amplification circuit 55, but this circuit also has a chiyoke coil 5.
7 is connected, the inflow of noise current can be prevented by its filtering action.

Furthermore, as described in the prior art section, the processing frequency of this high-frequency amplification circuit 55 is much higher than the frequency of the noise current, so the effect on noise generation is small, so the chiyoke coil 57 can be omitted. .

Note that the current flowing through this chiyoke coil 57 is usually small, about 1A, so
The wire diameter can be reduced, and there is no need to increase the size. Incidentally, the current flowing through the main amplifier 54 is approximately
It is 10A.

Furthermore, if the high frequency amplification circuit 55 is also connected to the circuit of the main amplifier 54, the chiyoke coil 57 can be omitted.

The effects of this embodiment are shown in Figures 1 and 2.
Further details will be given based on FIGS. 3 and 4 showing equivalent circuits in the figure.

As shown in FIG. 3, in the conventional circuit, the alternator 2 or other electrical loads 6, 7, 8
Noise currents I ₁ , I ₂ , I ₃ , and I ₄ generated from the noise currents are shunted to the battery 1 side and the radio 5 side, respectively. To explain this specifically using the noise current I ₄ of the direction indicating device 6 as an example, of the noise current I ₄ generated in the direction indicating device 6, the noise current I ₄₁ shunted to the battery 1 side is caused by the wire resistance R ₄ , R ₃ , R ₂ , and R ₁ and is absorbed by the battery 1 while being attenuated, and the noise current I ₄₂ shunted to the radio 5 side passes through the wire resistance R ₅ and is connected to the main amplifier 54 of the radio 5 and the high-frequency amplification circuit 55. flows into. Here, when comparing the noise currents I ₄₁ and I ₄₂ , since the direction indicating device 6 is disposed far from the battery 1 and close to the radio 5, the wire resistances R ₄ , R ₃ , R ₂ , R much smaller than the sum of ₁ , so the noise current is larger in I ₄₂ than in I ₄₁ .
In addition, other electrical loads 7, 8 and alternator 2
The same applies to

From this, the noise current flowing into radio 5
It can be seen that I ₅ is larger than the noise current I ₆ absorbed by the battery 1.

In contrast, in the circuit of this embodiment shown in FIG.
Noise currents I ₁₁ , I ₁₂ , I ₁₃ , I ₁₄ generated from 7 and 8
are divided into the battery 1 side and the radio 5 side, respectively. To explain this specifically using the noise current I ₁₄ of the direction indicator 6 as an example, of the noise current I ₁₄ generated in the direction indicator 6, the noise current I ₁₄₂ shunted to the radio 5 side is caused by the wire resistance R ₁₅ The noise current I ₁₄₁ flows into the radio frequency amplification circuit 55 of the radio 5 through the wire resistance R ₁₄ , and is shunted to the battery 1 side.
It flows into the main amplifier 54 of the radio 5 through R ₁₃ , R ₁₂ , R ₁₁ , and R ₁₆ . Here, when comparing and examining the respective noise currents I ₁₄₁ and I ₁₄₂ , as mentioned above, the wire resistance R ₁₅ is equal to the wire resistance R ₁₁ , R ₁₂ , R ₁₃ ,
Since it is much smaller than the sum of R ₁₄ and R ₁₆ , the noise current I ₁₄₁ is much smaller than the noise current I ₁₄₂ .
Furthermore, in the circuit where the noise current I ₁₄₁ flows into the main amplifier 54 of the radio 5, there is a battery 1 having a filter effect and a wire resistance R ₁₆ , so the noise current flowing into the main amplifier 54 is even smaller than I _141. Become something. Note that the same applies to the other electric loads 7 and 8 and the alternator 2.

From this, the high frequency amplification circuit 55 of the radio 5
Although the noise current I ₁₅ flowing into the radio 5 is not much different from the noise current I ₅ flowing into the radio 5 in FIG. 3, the noise current I ₁₇ flowing into the main amplifier 54 of the radio 5 is absorbed by the battery 1 in the middle of the circuit. It becomes extremely small due to the noise current I ₁₆ and wire resistance R ₁₆ .

In other words, the noise current generated in the direction indicating device 6, etc.
It can be seen that most of I ₁₁ , I ₁₂ , I ₁₃ , and I ₁₄ flows into the high frequency amplification circuit 55 of the radio 5, and almost none flows into the main amplifier 54.

FIG. 5 is a view corresponding to FIG. 2 showing another embodiment of this invention.

In this embodiment, the same reference numerals as in FIG. 2 are used for the parts corresponding to those in FIG. 2, and detailed explanation thereof will be omitted.

In another embodiment shown in FIG. 5, a circuit for a cassette stereo device is added to the circuit of the previous embodiment. Specifically, a radio/stereo changeover switch 59 is provided between the radio coil 57 and the radio switch 51, and the radio side circuit of the changeover switch 59 is equipped with a radio high frequency amplification circuit as in the previous embodiment. 55 is connected, and the equalizer circuit and motor control circuit 62 of the cabinet stereo device are connected to the stereo side circuit. Then, relay coil 5 is connected via diodes 60 and 61 so that power can be supplied from both circuits.
2 is connected.

With this circuit configuration, if the key switch 4 and radio switch 51 are turned on and the selector switch 59 is switched to the radio side,
The high frequency amplifier circuit 55 is energized, the relay coil 52 is also energized via the diode 61, the relay switch 53 is turned on, and the main amplifier 54 is also energized, so that the radio is operated. Furthermore, when the selector switch 59 is switched to the stereo side and the key switch 4 is turned on, the equalizer circuit for the cassette and the motor control circuit 62 are energized, the relay coil 52 is energized via the diode 60, and the relay switch 53 is turned on. Since the main amplifier 54 is also energized, the cassette stereo is operated.

In this circuit as well, only the circuit of the main amplifier 54 having a large current capacity is directly connected to the vehicle's power supply circuit 3 in the vicinity of the battery 1, and no other electrical load is connected to that circuit. Since it is separated from the electric load circuit, it is possible to achieve the same effects as in the previous embodiment.

Although two embodiments have been described above, this invention is not limited to the embodiments and the configurations shown in the drawings, but includes various embodiments within the scope of the utility model claims.

[Effect of idea]

As mentioned above, this idea connects at least the main amplifier of the audio device directly to the battery of the vehicle power circuit through an auxiliary switch that opens and closes in conjunction with the key switch, and connects that circuit directly to the battery of the vehicle power circuit. Since it is separated from the circuit, it is possible to effectively utilize the filtering effect of the battery or the wire resistance of the circuit to suppress the noise current from the alternator or other electrical load from flowing into the audio equipment. It is possible to obtain an acoustic device with less noise.

[Brief explanation of the drawing]

FIG. 1 is a power supply circuit diagram of a vehicle audio system showing the prior art, FIG. 2 is a power supply circuit diagram of a vehicle audio system showing an embodiment of this invention, and FIGS. 3 and 4 are diagrams of FIGS. FIG. 2 is an equivalent circuit diagram, and FIG. 5 is a diagram corresponding to FIG. 2 showing another embodiment. 1...Battery, 2...Alternator, 3...
Vehicle power supply circuit, 4... key switch, 5... radio (sound device), 50... relay (auxiliary switch), 54... main amplifier.

Claims (1)

[Claims for Utility Model Registration] In a vehicle audio circuit having an audio device connected to a vehicle power supply circuit including a battery and an alternator connected in parallel via a key switch and an audio device switch, at least one of the audio devices includes: The main amplifier is directly connected to the battery of the power supply circuit of the vehicle through an auxiliary switch that is opened and closed in conjunction with the key switch and the audio device switch, and is isolated from other electrical load circuits, so that the main amplifier side A power supply circuit for a vehicle audio device, characterized in that a noise current flowing into the vehicle is absorbed by a battery.