close

Вход

Забыли?

вход по аккаунту

JPH08186900

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JPH08186900
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to car
audio systems, and more particularly to an audio circuit for increasing the signal to noise (S / N)
ratio of an audio signal output.
[0002]
BACKGROUND OF THE INVENTION Successful installation of car audio components in a car can
be difficult because the car chassis is being used as a ground return for substantially all the
electrical accessories of the car. Automotive alternators and electrical accessories cause
significant changes in the power and control leads of the accessories and the magnetic field
surrounding the chassis of the vehicle. When a signal is sent from one component to another, the
proximity of the signal path may introduce noise into the device as it changes the
electromagnetic field. Also, noise may enter the components through the power supply or
internal signal paths. One way to handle the signal in a hostile noisy environment is to increase
the signal level so that the noise is relatively small, ie increase the signal-to-noise ratio by
increasing the signal level. It is.
[0003]
To be effective, the increase in signal level must be done at the source. Increasing the signal level
10-05-2019
1
after the source will also increase the noise floor. In car audio, the source is generally called a
deck or headpiece. The deck typically has four signal outputs to feed a four-speaker stereo
system in a car. The name given to this output represents the position of the speaker in the car.
That is, for the left channel (LC), the front left (LF) and the rear left (LR), and for the right channel
(RC), the front right (RF) and the rear right (RR). The peak signal level output of most decks is a
peak to peak value of about 2.0 volts rms (root mean square) to about 5.6 volts. This is because
virtually all modern vehicles operate at nominally 12.0 volts DC, and thus virtually all modern car
audio deck circuits function at nominal 12.0 volts DC. It is. Once this 12.0 volt level is adjusted
and connected to the audio circuit of the deck, the maximum achievable signal level is only about
2.0 volts. This is because the voltage in the semiconductor device of the deck drops sharply.
Thus, when the audio circuitry in the deck is functioning at 12.0 volts DC, the signal level is
approximately 2.0 volts rms.
[0004]
One of the common techniques to increase signal power levels is to convert the vehicle's nominal
12.0 volts DC to a higher level, such as 20 or 30 volts, and a preamp level output stage can
accommodate higher signal levels It is to be done. However, using the power supply converter
needed to increase 12.0 volts makes the deck expensive.
[0005]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a car audio
system having a high signal output.
[0006]
Another object of the present invention is to provide a low cost car stereo audio device with an
improved S / N ratio.
[0007]
Yet another object of the present invention is a car audio system using a deck having four signal
outputs to supply four speakers in a car and increasing the signal output without concomitantly
increasing the noise level It is to provide.
[0008]
10-05-2019
2
The invention is based on several concepts.
First, it was recognized that it was necessary to maintain a nominal 12.0 volt supply of the
vehicle to avoid undue expense.
Second, it has been recognized that adding an amplifier to the system alone can prevent an
increase in signal-to-noise ratio since both the signal as well as the noise have the same effect.
Third, it has been recognized that in order to obtain any increase in S / N ratio, other desirable
characteristics of the car audio device such as frequency response and distortion should not be
sacrificed.
[0009]
SUMMARY OF THE INVENTION According to one aspect of the invention, in a car audio system
using a deck having four signal outputs for feeding four speakers, the four outputs of the deck
are A coupling circuit is used to connect to the input of the stage, which may be a conventional
equalizer, an electronic crossover or an amplifier, whose output is then connected to the four
speakers Do. The coupling circuit has only two outputs, one for the left channel (LC) and one for
the right channel (RC), RF and RR speakers connected to the RC output, LF and LR speakers
Connect to the LC output. Thus, the LF and LR channels connect to one LC, and the RF and RR
channels connect to one RC. As a result, the signal level was increased by 6 dB, and the
accompanying 6 dB increase in noise level was not observed.
[0010]
According to another feature of the invention, the coupling circuit of the invention comprises a
unity gain buffer amplifier. This makes it possible to reliably prevent the loss of the signal
without increasing the noise level.
[0011]
10-05-2019
3
Application of the coupling circuit of the present invention to a car audio system using a nominal
12.0 volt power supply is found to convert signal output levels of a typical 1.8 volt rms deck to a
3.6 volt rms deck The Furthermore, such an improved device offers the advantages of lower
inductive noise, lower system noise, and less system hiss, with ± 0.05 dB frequency response at
20 Hz to 20 KHz, and full distortion. 0.01%, and the S / N ratio can be maintained at 120 dB or
more.
[0012]
The coupling circuit of the present invention can provide the most benefit when used with a
conventional four channel deck, but can also be used with a two channel deck. However, the
noise floor increases because the noise that enters the circuit is correlated.
[0013]
The constitutions and embodiments of the present invention will be listed below.
[0014]
1.
A circuit for coupling an audio deck to a speaker system, the audio deck being coupled to provide
first and second RCs, and third and fourth LC outputs. (C) a first noninverting amplifier means,
(b) a second inverting amplifier means, and (c) a third noninverting amplifier means (d). B) a
fourth inverting amplification means, (e) each amplification means has an input and an output,
and the circuit further comprises (f) first and second RC deck outputs of the first amplification
means Means for connecting the input of the second amplification means to the other of the first
and second RC deck outputs, and (g) the input of the third amplification means for the first and
second LC outputs Connected to one of the first and second LC outputs of the fourth
amplification means (H) said first and second amplification means outputs cooperate to provide
an audio signal to at least one RC speaker, (i) said third and second A circuit for coupling an
audio deck to a speaker system, characterized in that the four amplification means outputs
cooperate to provide an audio signal to at least one LC speaker.
10-05-2019
4
[0015]
2. An RC output jack further comprising a center conductor and a shield, wherein the center
conductor is connected to one of the first and second amplifier means outputs and the shield is
connected to the other of the first and second amplifier means outputs. The circuit as described
in 1 above.
[0016]
3. The system further includes an LC output jack having a center conductor and a shield,
wherein the center conductor is connected to one of the third and fourth amplifier means
outputs and the shield is connected to the other of the third and fourth amplifier means outputs.
The circuit as described in 1 above.
[0017]
4. A circuit according to claim 1, wherein the amplification means each comprise a unity gain
amplifier.
[0018]
5. The circuit according to claim 4, wherein the amplification means each comprise a 1: 1
transformer.
[0019]
6. The circuit according to claim 4, wherein the amplification means each comprise an
operational amplifier.
[0020]
10-05-2019
5
7. An audio device, the device comprising: (I) a circuit for coupling an audio deck to a speaker
system, the audio deck comprising a first and a second RC, and a third and a fourth LC Having at
least one RC and LC output coupled to provide an output, said circuit comprising: (a) a first noninverting amplification means; (b) a second inverting amplification means; c) a third non-inverted
amplification means, (d) a fourth inversion amplification means, (e) each amplification means has
an input and an output, and the circuit further comprises (f) a first Means for connecting the
input of the amplification means to one of the first and second RC deck outputs and the input of
the second amplification means to the other of the first and second RC deck outputs; (g) a third
Connecting the input of the second amplification means to one of the first and second LC
outputs, A circuit for coupling an audio deck to a speaker system, comprising: means for
connecting the input of the amplification means to the other of the first and second LC outputs;
(II) (a) an RF speaker; (b) An RR speaker, (c) an LF speaker, and (d) an LR speaker, and (III) the RF
and RR speakers connected in series with the first and second amplifier means outputs, the LF
and LR speaker An audio device connected in series with the second and third amplifier means
outputs.
[0021]
8. The system further includes an RC output jack having a center lead and a shield, wherein
the center lead is connected to one of the first and second amplifier means outputs, and the
shield is connected to the other of the first and second amplifier means outputs. The apparatus
as described in 7 above.
[0022]
9. The system further includes an LC output jack having a center conductor and a shield,
wherein the center conductor is connected to one of the third and fourth amplifier means
outputs and the shield is connected to the other of the third and fourth amplifier means outputs.
The apparatus according to the above 8, which is
[0023]
10.The apparatus according to claim 10, wherein the amplification means each comprise a
unity gain amplifier.
10-05-2019
6
[0024]
11.The device according to claim 10, wherein the amplification means each comprise a 1: 1
transformer.
[0025]
12.The device according to claim 10, wherein the amplification means each comprise an
operational amplifier.
[0026]
13.Device according to claim 10, further comprising means in the device for detecting the
absence of a differential load and for providing a differential input.
[0027]
14.A circuit for coupling an audio deck to a speaker system, the audio deck having RC and LC
outputs, the circuit comprising: (a) a first non-inverting amplification means; (b) a second (C) a
third non-inverting amplification means, and (d) a fourth inverting amplification means, (e) said
amplification means each having an input and an output, said circuit further comprising: (F)
means for connecting the input of the first amplification means to the RC deck output, and means
for connecting the input of the second amplification means to the RC deck output, and (g) input
of the third amplification means to the LC deck output Means for connecting and for connecting
the input of the fourth amplification means to the LC deck output, and (h) providing the audio
signal to at least one RC speaker, said first and second amplification means outputs Work
together, (i) at least one LC speaker To provide an audio signal, the third and fourth amplifying
means output, characterized in that the cooperating circuitry for coupling the audio deck speaker
system.
[0028]
15.An RC output jack further comprising a center conductor and a shield, wherein the center
conductor is connected to one of the first and second amplifier means outputs, and the shield is
connected to the other of the first and second amplifier means outputs 15. The circuit according
to 14 above.
[0029]
16.A center conductor and an LC output jack having a shield, the center conductor being
connected to one of the third and fourth amplifier means outputs and the shield being connected
to the other of the third and fourth amplifier means outputs The circuit according to claim 14,
10-05-2019
7
characterized in that:
[0030]
17.The circuit of claim 14 wherein said amplifying means each comprises a unity gain
amplifier.
[0031]
The above and other objects, details and advantages of the present invention will become
apparent from the following detailed description of the preferred embodiment, taken in
conjunction with the accompanying drawings.
[0032]
FIG. 1 schematically shows a conventional car audio system having a four channel output from
the deck 10 for feeding four speakers 11-14.
The deck 10 has a jack for the right front channel labeled RF, a jack for the right rear channel
labeled RR, a jack for the left front channel labeled LF, and a left rear channel labeled LR. Have
four jacks for jacks.
L and R mean the conventional L and R channel outputs of a stereo device.
The signal outputs of the RF and RR jacks are synchronized, and the signal outputs of the LF and
LR jacks are also synchronized.
A cable connects each jack to a respective speaker via a conventional equalizer, electronic
crossover or amplifier 15.
Therefore, the RF jack is connected to the RF speaker 11, the RR jack to the RR speaker 12, the
LF jack to the LF speaker 13, and the LR jack to the LR speaker 14.
10-05-2019
8
As is conventional, the deck power supply is a conventional 12.0 volt power supply 16 for an
automobile.
In a typical transistorized deck, the signal output level at the jack is up to about 1.8 rms volts.
[0033]
FIG. 2 schematically shows the basic circuit of the coupling circuit of the present invention.
Similar reference numerals are used in FIG. 2 and other numerals are used for elements similar to
those used in FIG.
The input jacks labeled RF, RR, LF, and LR are cabled to the corresponding labeled output jacks
of the deck 10. However, before going to the next stage 15, the circuit includes four unity gain
amplifiers 20-23, two of which 20, 22 are non-inverting amplifiers and the remaining two 21, 23
are It is an inverting amplifier. The two output jacks 25 and 26 are connected as shown. In
particular, the center lead of the RF input jack is connected to the non-inverting amplifier 20 and
the output of the amplifier is connected to the center lead of the RC output jack 25 while the
center lead of the RR input jack passes the inverting amplifier 21 to the RC output jack 25.
Connected to the shield of The LF and LR inputs are likewise connected to the LC output jack 26
via the amplifiers 22 and 23. Thus, the front of the four separate audio channels are connected to
the two left and right channels as shown, effectively doubling the signal level at each output jack
25, 26. The output jacks 25, 26 may be connected to the four speakers 11-14 through a
conventional next step, as shown. In practice, both of the two RC speakers 11, 12 are in series
with the RF and RR deck outputs, and both of the two LC speakers 13, 14 are in series with the
LF and LR deck outputs.
[0034]
A unity gain amplifier that provides the correct phase of the signal without increasing the noise
level can be obtained in various ways. One way is to show only the RC side in FIG. 3, but with
transformers 30, 31 for the RF and RR channels, winding the transformer coil to non-reversal
coupling to the RF channel, to the RR channel Provide a reverse coupling. Connect the left
channel as well. Also, in this and other embodiments, the amplifier is replaced to make the RR
10-05-2019
9
channel amplifier non-inverting, and the RF channel amplifier is inverting and the desired signal
add-on effect when connected in series with the speaker. It is understood that it may be provided.
Although transformer couplings are expensive, operational amplifiers (Op-Amp) offer similar
functionality at much lower cost. Such an embodiment is shown in FIG.
[0035]
The circuit shown in FIG. 4 uses a commercially available TL084 conventional quad Op-Amp
integrated circuit (IC) with four independent Op-Amps 40-43. Other Op-Amp ICs may be
substituted. Connected to each Op-Amp is the same external component to obtain a unity gain
amplifier. An inversion or non-inversion function was achieved by coupling the input either to the
Op-Amp non-inverted (+) input of the RF and LF channels, or to the inverted (-) input of the RR or
LR channel. Exemplary component values are shown in the figure. The applied voltage (V +) was
12 volts DC. When using another manufacturer's Op-Amp, other component values may be
required. Op-Amp IC manufacturers typically provide sample circuits to achieve unity gain in
their ICs.
[0036]
The circuit shown in FIG. 4 has all of the above advantages, such as doubling the signal output at
RC and LC jacks 25 and 26 without loss of frequency response or distortion, and maintaining
signal-to-noise ratio above 120 dB. I will provide a. The impedance of the illustrated circuit is
about 100 ohms. By doubling the signal level output, the input sensitivity of the next stage
amplifier 15 can be reduced. This makes it possible to enhance program material output with
less hiss.
[0037]
When the circuit shown in FIG. 4 is used with a two channel deck, it is necessary to place a
conventional y-adapter between the two deck outputs and the four circuit inputs of the coupling
circuit of the invention.
[0038]
The circuit of FIG. 4 may be connected between any two preamplifier level components.
10-05-2019
10
[0039]
It is understood that in the embodiment shown above, the coupling circuit is not connected
directly to the speaker, but is usually connected through another stage that includes a buffer that
actually drives the speaker.
Thus, it is to be understood that the expression "connecting to the speaker" in the present
description includes conventional inverting audio stages such as equalizers, electronic crossovers
or amplifiers.
[0040]
In the described embodiment, the coupling circuit drives the conventional balanced output, ie the
input to the next stage, whether with four or two inputs.
However, in some devices, the input to the next stage is unbalanced, which means that a coupling
circuit with a balanced input will drive an unbalanced output. FIG. 5 is a block diagram of a
modified coupling circuit to compensate for this non-equilibrium condition.
[0041]
FIG. 5 illustrates half of the modification of the coupling circuit, ie the circuit of the left or right
channel. In this circuit, the right or left front signal is applied to the unity gain amplifier 60 and
the right or left front signal is applied to the inverting unity gain amplifier 61. The output of
amplifier 60 is applied through input resistor 63 to the non-inverting input of unity gain buffer
amplifier 62 and through input resistor 65 to the inverting input of unity gain buffer amplifier
64. The output of buffer amplifier 62 is cross connected via resistor 66 to the non-inverting
input of buffer amplifier 64, and the output of buffer amplifier 64 is connected via resistor 67 to
the non-inverting input of buffer amplifier 62.
[0042]
Since the output of buffer amplifier 64 is inverted with respect to the input of buffer amplifier
62, and the output of buffer amplifier 62 is inverted with respect to the input of buffer amplifier
10-05-2019
11
64, each of the non-inverting inputs of these amplifiers is The two signals applied to each cancel
each other so that the output of each amplifier is essentially only responsive to the signal applied
to each inverting input.
[0043]
When the amplifier output lead is grounded as shown by the hatching connecting this output to
ground, there is no signal applied from this output line to the non-inverting output of buffer
amplifier 62, and amplifier 60 to buffer amplifier It is apparent that the signal applied to the noninverting input of 62 is no longer canceled by the output signal of buffer amplifier 64.
Thus, the output of buffer amplifier 62 is increased to substantially double its original amplitude,
substantially to the output of the circuit between terminals 70 and 71, in the case where the
output of amplifier 64 is not grounded. Provide a signal of the same amplitude. It is obvious that
the same effect can be obtained when the output of the buffer amplifier 62 is grounded.
[0044]
Thus, the circuit of FIG. 5 provides an output signal of greater amplitude than the embodiment
shown in FIGS. 2-4 when none of its output lines are grounded, and also when one of the output
lines is grounded. Maintain the output level substantially.
[0045]
Having described presently preferred embodiments of the present invention, it is to be
understood that the present invention may be embodied in other specific forms without
departing from its basic characteristics.
Accordingly, the present embodiments are to be considered in all respects as illustrative and not
restrictive. The scope of the invention is indicated by the appended claims rather than the
foregoing description.
[0046]
Brief description of the drawings
10-05-2019
12
[0047]
FIG. 1 FIG. 1 is a schematic view of a conventional car audio system using a four channel deck.
[0048]
FIG. 2 FIG. 2 is a schematic view of one form of the coupling circuit of the present invention.
[0049]
FIG. 3 FIG. 3 is a schematic view of a portion of another form of the coupling circuit of the
present invention.
[0050]
FIG. 4 FIG. 4 is a schematic view of still another form of the coupling circuit of the present
invention.
10-05-2019
13
1/--страниц
Пожаловаться на содержимое документа