JP3364010B2 - Audio equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio device, and more particularly to an S / N ratio in a circuit which has a sound quality adjusting function such as a graphic equalizer or surround and a sound volume adjusting function for all sound volumes and fulfills these functions. Good audio equipment.

[0002]

2. Description of the Related Art FIG. 4 is an explanatory diagram of a cassette tape player as an example of a conventional audio device. The figure shows the outline of the playback circuit for one channel. This playback circuit has the function of adjusting the volume of the audio signal over the entire frequency band and adjusting the sound quality by attenuating from the attenuation in a specific frequency band. I have. Here, 1 is a read head, 2 is a preamplifier, 3 is an electronic volume, 4 is a sound quality adjustment circuit (tone control circuit) that performs sound quality adjustment from attenuation in a specific frequency band to emphasis, 5 is an electronic volume, 6 is a main amplifier , 7 is a speaker, and 8 is a control circuit. Further, VR1 is a volume adjusting volume, and VR2 is a sound quality adjusting volume.

The volume VR1 indicates whether the volume should be reduced depending on whether the set position is lower or upper. Therefore,
The control circuit 8 to which the setting of the volume VR1 is input generates a control signal V3 having a current value corresponding to the setting of the volume VR1 and outputs this to the electronic volume 5 as the control signal. The electronic volume 5 performs a volume operation according to the control signal V3 and has a volume adjusting function.

The volume VR2 is in an unadjusted state of sound quality adjustment or in an attenuated state corresponding to a deviation from the midpoint depending on whether the set position is at the midpoint, below the midpoint, or above the midpoint. Or the emphasis state. Therefore, the control circuit 8 to which the setting of the volume VR2 is also input generates a control signal V2 having a current value according to the setting of the volume VR2 and outputs it to the tone control circuit 4 as the control signal. The tone control circuit 4 has a filter corresponding to a specific frequency band and an electronic volume, and this electronic volume performs a volume operation in accordance with the control signal V2 and has a sound quality adjusting function of particularly attenuating or emphasizing the specific frequency band. .

Further, the control circuit 8 controls the volume VR2.
The control signal V1 having a current value corresponding to the setting of the volume VR2 is generated only when the setting position of is above the midpoint, that is, when the sound quality adjustment is in the emphasized state.
Output as a control signal for the navel. The electronic volume 3 is
The volume operation is performed according to the control signal V1, and only when the sound quality adjustment is in the emphasized state, the sound volume is adjusted according to the degree of the sound quality adjustment prior to the sound quality adjustment in the tone circuit 4.

The reproducing circuit having such a structure operates as follows. An audio signal A is read from a tape (not shown) via the read head 1, and the preamplifier initially amplifies the audio signal A to generate an audio signal B. By this amplification, the signal level of the audio signal B is made to be almost the full dynamic range in the signal processing circuit. When the sound quality adjustment is unadjusted or attenuated, the audio signal B is directly converted into the audio signal C through the electronic volume control 3, and when the sound quality adjustment is emphasized, the audio signal is previously emphasized by the tone control circuit 4 in advance. B is attenuated by the electronic volume 3 into an audio signal C.

Further, the sound quality of the audio signal C is adjusted by the tone control circuit 4 to obtain the audio signal D. The audio signal D is also maintained at a signal level that is almost the full dynamic range in the signal processing circuit. Then, the volume of the audio signal D whose sound quality has been adjusted is adjusted by the electronic volume 5 into an audio signal E having a desired signal level, which is power-amplified by the main amplifier 6 and then output from the speaker 4 as a final sound. Output to the outside.

[0008]

In such a conventional audio apparatus, an electronic volume is adopted from the viewpoints of noise countermeasures and easiness of control, etc. by arranging the wiring from the volume which is directly operated, but the volume is adjusted. A tone circuit for adjusting the sound quality is arranged in front of the electronic volume for. The reason for this is to maximize the S / N ratio within the range where the signal waveform is not distorted. For this purpose, it is necessary to adjust the sound quality while keeping the audio signal at a signal level almost at the full dynamic range. Because there is.

Further, in front of the tone control circuit, an electronic volume for attenuating the audio signal only when the tone control is emphasized is arranged. The reason for this is that when the sound quality adjustment is in the emphasized state, the specific frequency band is amplified for emphasis and the signal level exceeds the dynamic range and the signal waveform is distorted if nothing is done to prevent such inconvenience. This is because. As a result, not only when the sound quality adjustment is in the attenuated state or the unadjusted state but also in the emphasized state, the sound quality adjustment is performed in a state where the signal waveform is not distorted and the signal level is maintained almost at the full dynamic range. Conventionally, the above-mentioned configuration was considered to have the best S / N ratio.

However, the demand for improving the performance of the audio device is strict, and the demand for improving the sound quality in particular is unavoidable. Therefore, even in an audio device having a sound quality adjusting circuit in addition to the volume adjusting circuit, further improvement of the S / N ratio is required. An object of the present invention is to solve such a problem of the conventional technique and to realize an audio device having a good S / N ratio.

[0011]

In order to achieve this object, the structure of an audio apparatus of the present invention is such that the volume of an audio signal is adjusted in the entire frequency band and the sound quality is adjusted from attenuation in a specific frequency band to emphasis. an audio apparatus which performs bets, audio signal or the attenuated audio
Audio signal as an input, a first electronic volume that performs volume operation and output according to the sound quality adjustment only when the sound quality adjustment is in an emphasized state, and an output signal of the first electronic volume
And an audio signal and output an audio signal
Attenuated to produce an attenuated audio signal
A signal generation circuit, which receives the attenuated audio signal , performs a volume operation according to the sound quality adjustment and performs filtering corresponding to the specific frequency band, and when the sound quality adjustment is in an emphasized state, the sound quality adjustment is performed on the attenuated audio signal. for <br/> generates a signal of opposite phase adjusted tone Te, sound quality adjustment is unregulated state signal to an audio signal or audio signal is adjusted sound quality when the signal occurs, the attenuation state tone control a signal generating circuit which does not generate or signal to generate a zero level signal when the the output of the signal generating circuit
A second electronic volume that receives the attenuated audio signal and performs a volume operation according to the volume adjustment ,
If the sound quality adjustment is unadjusted, the attenuated audio signal
Audio signal without being attenuated by the attenuation signal generation circuit
From the attenuation signal generation circuit to the second electronic volume
It is a force . In addition, another invention audio device
The configuration is based on the audio signal input and strong sound quality adjustment.
Volume operation and output according to sound quality adjustment only
A first electronic volume for exerting force and an audio signal or
Receives a signal whose audio quality has been adjusted, and adjusts the sound quality
Corresponding to the volume operation and filter corresponding to a specific frequency band.
When the sound quality adjustment is emphasized,
Is the volume adjusted by receiving the output of the first electronic volume.
Phase signal is generated, and when the sound quality adjustment is in the attenuated state,
A signal whose audio quality has been adjusted from the audio signal or audio signal
Generate a signal with the opposite phase for which the sound quality has been adjusted
A zero level signal is generated or sent when there is no adjustment.
Signal generation circuit that does not generate a signal and the output of this signal generation circuit.
The second that receives the force and performs the volume operation according to the volume adjustment
With the electronic volume of, the sound quality adjustment is emphasized.
In the state of signal generation, the second electronic volume is
Output for subtracting the output of the path and the output of the first electronic volume
And are added.

[0012]

In an audio device that performs sound quality adjustment and volume adjustment from attenuation to enhancement, conventionally, an electronic volume for preventing waveform distortion at the time of enhancement, a tone quality adjustment circuit corresponding to a specific frequency band, and an electronic volume for volume adjustment have been used. Were serially inserted into the audio signal line in this order. For this reason, noise generated in all these circuits is always superimposed on the audio signal. On the other hand, in the configuration of the present invention as described above, only the second electronic volume for adjusting the volume is serially inserted in the line of the audio signal, and most of the other circuits are of the audio signal. It is provided in parallel with the line.

That is, the first for preventing waveform distortion at the time of emphasis
The electronic volume and the signal generation circuit that occupies the main part of the circuit that functions as the sound quality adjustment circuit are in parallel with the line of the audio signal. Moreover, since the first electronic volume operates only when the sound quality adjustment is in the emphasized state, noise does not occur in other cases. Further, since the signal generation circuit operates only when the sound quality adjustment is in the emphasized state or the attenuated state, noise does not occur in other cases.
Furthermore, when the sound quality adjustment is not in the emphasized state, the signal path is shortest in each state, and it is difficult to receive external interference.

Thus, when the sound quality adjustment is in the attenuated state, only the noise from the signal generating circuit for sound quality adjustment and the second electronic volume for sound volume adjustment affects the audio signal, and the sound quality adjustment is not adjusted. When is the second
Only noise from the electronic volume of will affect the audio signal. Therefore, the audio device of the present invention is
The S / N ratio is improved over the conventional one.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A cassette tape player as an embodiment of an audio apparatus of the present invention will be described below with reference to the drawings. FIG. 1 shows one of the cassette players.
An outline of a reproduction circuit for channels is shown. This corresponds to FIG. 4 of the related art, and similar components are designated by the same reference numerals. Therefore, these explanations are omitted, and the differences will be mainly described below. Here, 20 receives the audio signal B from the preamplifier 2 and receives the audio signal B to the electronic volume 30.
Is an adder / subtractor circuit that generates an audio signal B'by subtracting the signal from. This subtraction is performed when the electronic volume 30 is in the emphasized state, and otherwise the addition / subtraction circuit 20 becomes the same as the through state. This circuit is a circuit similar to the adding / subtracting circuit 50, and the subtraction is performed by receiving a signal having a phase opposite to that of the audio signal B from the electronic volume 30.

A first electronic volume 30 receives the audio signal B '(or the audio signal B, B = B' except in the emphasized state) which is the output of the adder / subtractor circuit 20 and generates an output signal of a reverse phase. And add it to the adder / subtractor circuit 20.
Reference numeral 40 denotes a tone signal generation circuit as a signal generation circuit, which receives an audio signal B ′ output from the addition / subtraction circuit 20 and an output D from the addition / subtraction circuit 50 and outputs C ′ after sound quality adjustment.
Is sent to the addition / subtraction circuit 50. Reference numeral 50 is an addition / subtraction circuit that adds the audio signal B ′ and the output C ′ of the tone signal generation circuit 40. The electronic volume 5 corresponds to the second electronic volume.

The electronic volume 30 is basically the same as the electronic volume 3 in FIG. 4, but operates only when the control signal V1 indicates that the sound quality adjustment is in the emphasized state. Sometimes it doesn't work. Such a function is achieved by setting different reference voltages in the electronic volume to be compared with the control signal. As a result, when the sound quality adjustment is in the attenuated state or the unadjusted state, the output C does not include noise.

The tone signal generation circuit 40 has an electronic volume and a filter. This electronic volume performs volume operation according to the control signal V2. The filter performs filtering corresponding to a specific frequency band. Then, when the control signal V2 indicates that the sound quality adjustment is in the emphasized state, the in-phase signal C'from the audio signal B '.
And the control signal V2 indicates that the sound quality adjustment is in the attenuated state, a signal C ′ having an opposite phase is generated from the audio signal D, and the control signal V2 indicates that the sound quality adjustment is in the unadjusted state. When shown, a zero level signal is generated and the generated signal C ′ is sent to the adder / subtractor circuit 50. Therefore, the output C ′ does not include noise when the sound quality adjustment is not adjusted.

FIG. 2A shows a concrete configuration of the tone signal generation circuit 40. This is because the audio signal B ′ subtracted by the output C of the electronic volume 30 is input when the sound quality adjustment is in the emphasized state, and the electronic volume 41 that operates only in the emphasized state and the audio signal D are input as the sound quality adjustment. Electronic volume 4 that operates only in the decay state
2, an output of the electronic volume control 41 is input as it is, and an output of the electronic volume control 42 is inverted and added together, and an output of the addition circuit 43 is input, and a frequency component of a specific frequency band determined by a filter characteristic is input. And a filter 44 that cuts off frequency components other than that band.

FIG. 2B shows another configuration example of the tone signal generation circuit 40. This is because when the sound quality adjustment is in the strong adjustment state, the audio signal B ′ subtracted by the output C of the electronic volume 30 is input, and when the sound quality adjustment is in the attenuated state, the inverted signal of the audio signal D is input and selectively output. Switch circuit 45 for controlling and electronic volume 4 that operates only when the sound quality adjustment is in the attenuated state or the emphasized state
1 and an output of the electronic volume control 41 as input, and a filter 4 that outputs only frequency components in a specific frequency band determined by the filter characteristics and blocks frequency components other than that band.
4 and.

The adder / subtractor circuit 50 receives the audio signal B '(= audio signal B, in a state other than the emphasized state) which is the output of the adder / subtractor circuit 20 and the output C'of the signal generating circuit 40, and outputs the audio signal B'. On the other hand, the signal generation circuit 40
The output C ′ is added to generate the audio signal D. Then, the audio signal D is output to the electronic volume 5 for volume adjustment. In this way, by directly inputting the audio signal B ′ (audio signal B) from the preamplifier 2 to the addition / subtraction circuit 50 via the addition / subtraction circuit 20, the electronic volume 30 and the tone signal generation circuit 40 are parallel to the audio signal line. The connection state becomes. Note that, although a specific configuration example of the electronic volume 5 is shown in FIG. 2C, the other electronic volumes are substantially the same.

The operation under such a configuration will be described.
Since the operation of the entire device has already been described in the conventional example,
In particular, the operation relating to the sound quality adjustment will be described with reference to FIG. First, when the tone control is emphasized, the control signal V1 operates the electronic volume 30, and the output C of the electronic volume 30 is input to the adder / subtractor circuit 20 to subtract the output of the electronic volume 30 from the attenuated signal. As a result, the audio signal B'is generated. Then, this is sent to the tone signal generation circuit 40 and the addition / subtraction circuit 50. As a result, the level of the audio signal is attenuated according to the sound quality adjustment, so that the level of the audio signal D does not exceed the dynamic range even if the signal C ′ for the next enhancement is added.

Further, in the emphasized state, the audio signal B'attenuated by the output of the electronic volume 30 is amplified by the tone signal generation circuit 40 by a specific frequency band to generate a signal C '. Then, this is added to the audio signal B ′ and the like by the adder / subtractor circuit 50 and output as the audio signal D. As a result, the signal level of the added signal increases correspondingly. Therefore,
The audio signal D in this state is emphasized and adjusted only in a specific frequency band. Then, the volume of the audio signal D is adjusted by the electronic volume 5 (FIG. 3A).
reference).

More specifically, when the tone control signal generating circuit 40 is emphasized, the electronic volume 30 performs a damping operation with the same amount of gain. When the gain of the tone signal generation circuit 40 is N, the audio signals B ′ and C ′ are: B ′ = B / (N + 1) C ′ = αNB ′ where α is a band-limited frequency. Therefore, the signal D becomes D = B '+ C' = B / (N + 1) + αNB '= B / (N + 1) + αNB / (N + 1) = B × (1 + αN) / (N + 1). Therefore, a signal for amplifying the control signal V3 by N + 1 times is generated and the signal D is multiplied by N + 1 by the electronic volume 5. As a result, E = D (N + 1) = B (1 + αN). In this way, in the emphasized state in which the electronic volume 30, the tone signal generation circuit 40, and the electronic volume 5 all operate, the S / N ratio is the same as the conventional one.

Next, when in the attenuated state, the electronic volume 30 stops operating and the tone control signal generation circuit 40
Operates with the audio signal D as an input. Therefore, a feedback system in which the audio signal D is returned to the input of the tone signal generation circuit 40, and only the component of the specific frequency band attenuated and phase-inverted by the tone signal generation circuit 40 is added to the audio signal B by the addition / subtraction circuit 50. Works. If you add a signal whose phase is inverted in this way,
The signal level of the added signal is correspondingly reduced.

Therefore, the audio signal D in this state is attenuated and adjusted only in a specific frequency band. Furthermore, the volume of the audio signal D is adjusted by the electronic volume 5 (see FIG. 3B). In this way, in the attenuated state in which the electronic volume 30 does not operate and only the tone control signal generation circuit 40 and the electronic volume 5 operate, noise resulting from the operation of the electronic volume 30 does not occur, so the S / N ratio is improved compared to the conventional case. To be done.

Finally, in the unadjusted state, the electronic volume 30 and the tone signal generation circuit 40 both stop operating. Therefore, the audio signal B is directly used as the audio signal D via the adder / subtractor circuit 50. The volume of the audio signal D is adjusted by the electronic volume 5 (see FIG. 3).
(See (c)). In this way, in the unadjusted state in which the electronic volume 30 and the tone signal generation circuit 40 do not operate and only the electronic volume 5 operates, noise due to the operation of the electronic volume 30 and the tone signal generation circuit 40 does not occur. , The S / N ratio is further improved compared to the conventional one. That is,
When the sound quality adjustment is not in the emphasized state, the signal path is shortest in each state, and it is difficult to receive external interference.

The configuration of FIG. 1 shows a circuit for adjusting only one frequency band for an audio signal of only one channel, but this shows only the basic minimum configuration. Therefore, a circuit for sound quality adjustment configured by a tone signal generation circuit or the like for another frequency band is replaced by the circuit for sound quality adjustment (30,
40) may be provided in parallel. In the graphic equalizer, it is often the case that about 5 to 7 such circuits for adjusting the sound quality are provided in parallel. 2 channels,
In the case of a 4-channel device, basically, the above circuits are provided in parallel for the number of channels except that the control signals are interlocked. In any case, the present invention is merely implemented multiple times.

By the way, in the embodiment, in the sound quality emphasizing state, the in-phase signal whose volume is adjusted by the tone signal generation circuit 40 is generated with respect to the attenuated signal obtained by subtracting the value of the electronic volume 30, but the electronic volume is generated. When the signal of 30 is directly received and a volume-adjusted signal is generated and then added to an audio signal (or a signal whose sound quality is adjusted), an audio signal (or a signal whose sound quality is adjusted) is simultaneously converted into an electronic signal. It is also possible to perform a subtraction corresponding to the level of the signal of the volume 30 and input this to the electronic volume 5. In the above case,
The signal of the child volume 30 is directly applied to the tone signal generation circuit 40.
Since it is input, the signal of the electronic volume 30 is added / subtracted
The signal line input to the tone signal generation circuit 40 via the signal line 20
Is unnecessary. Emphasized state as described in the prior art
Occasionally, only the amount of electronic volume boosted by the tone control circuit 4 of FIG.
The relationship in which the audio signal B is attenuated by the volume 3
Therefore, in the above case, the input of the electronic volume 30 is over.
It becomes the Dio signal B.

[0030]

As can be understood from the above description, in the audio device of the present invention, the first electronic volume that operates when the sound quality adjustment is in the emphasized state and the sound quality adjustment in the emphasized state and the attenuated state are performed. A signal generating circuit that operates from time to time is provided in parallel with the line of the audio signal to perform sound quality adjustment from attenuation in a specific frequency band to emphasis,
A second electronic volume is provided in series with the line of the audio signal to adjust the volume. As a result, when the sound quality adjustment is in the attenuated state and the non-adjusted state, the S / N ratio is improved as compared with the conventional case because the electronic volume 30 and the like are not operated. As a result, an audio device with a good S / N ratio can be realized.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an outline of a cassette tape player as an embodiment of an audio device having a configuration of the present invention.

FIG. 2 is a detailed diagram of the tone signal generation circuit and the like.

FIG. 3 is an operation explanatory diagram of the audio device having the configuration of the present invention.

FIG. 4 is a schematic diagram of a conventional cassette tape player.

[Explanation of symbols]

1 read head 2 preamplifier 3 electronic volume 4 Sound quality adjustment circuit (tone circuit) 5 electronic volume 6 Main amplifier 7 speakers 8 control circuit 30 electronic volume 40 tone signal generation circuit 41,42 Electronic volume 43 Adder circuit 44 Filter 45 switch circuit 50 adder / subtractor circuit

Claims (2)

(57) [Claims] 1. An audio device for adjusting a volume of an audio signal and adjusting a sound quality from attenuation to enhancement in a specific frequency band, wherein the audio signal or the attenuated audio signal is input and the sound quality adjustment is emphasized. A first electronic volume that performs volume operation and output according to the sound quality adjustment only in the state, an output signal of the first electronic volume, and the audio
Signal and the audio signal to the output signal.
Attenuating to produce said attenuated audio signal
Performing a signal generating circuit, wherein the attenuation audio signal, the audio signal Gomata is a filtering of the audio signal is subjected to the signal adjusted sound quality corresponding to the specific frequency band and the volume operation in accordance with the tone control be those, wherein when the sound quality adjustment of the emphasized state generates a signal of the same phase which is the tone control for the attenuation audio signal, signal that the tone adjusting said audio signal or the audio signal when the attenuation state is adjusted tone generating a signal of opposite phase that tone control with the item, wherein the tone control and a signal generating circuit which does not generate or signal to generate a zero level signal when the unregulated condition, the output of the signal generating circuit of this attenuation A second volume operation that receives an audio signal and that corresponds to the volume adjustment
And an electronic volume of, which is provided when the sound quality adjustment is in an unadjusted state.
Before the signal is not attenuated by the attenuation signal generation circuit
From the attenuation signal generating circuit as the audio signal,
An audio device characterized by being input to a second electronic volume . 2. A volume control and a special feature for an audio signal.
Performs sound quality adjustment from emphasis in constant frequency band to emphasis
In an audio device, the audio signal is input and the sound quality adjustment is emphasized.
Volume operation and output according to the sound quality adjustment only when
For adjusting the sound quality of the first electronic volume for performing force and the audio signal or the audio signal
It received the signal, volume dynamic in accordance with the previous Symbol sound quality adjustment
And the filtering corresponding to the specific frequency band.
If the sound quality adjustment is emphasized, the first
In-phase signal whose volume is adjusted by receiving the output of the electronic volume
Occurs and the sound quality adjustment is in the attenuated state, the
A signal whose sound quality has been adjusted for the audio signal or the audio signal.
Signal of the opposite phase with sound quality adjusted for
Generates a zero level signal when the quality adjustment is unadjusted
Or a signal generating circuit that does not generate a signal and receives the output of this signal generating circuit to respond to the volume adjustment.
A second electronic volume for volume operation,
For example, when the sound quality adjustment is emphasized state, wherein the second electronic volume, audio device, characterized in that output and is added to the output is subtracted and output the first electronic volume of the signal generating circuit .