JP2669975B2 - Sound 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 such as a stereo or a radio cassette recorder.

[0002]

2. Description of the Related Art Recent audio devices such as stereos are shown in FIG.
As shown in FIG. 5, a graphic equalizer 52 is provided so that the sound quality can be adjusted.

The audio signal amplified by the preamplifier 51 is input to the graphic equalizer 52. The graphic equalizer 52 can freely set the amplification degree (or the attenuation degree) for each frequency band, and thus, a desired sound quality can be obtained. The output of the graphic equalizer 52 is a flat amplifier 53
Power amplifier 5 which is amplified by
5 is input. The volume of the speaker 56 is adjusted by the volume 54 provided on the input side of the power amplifier 55.

[0004] As shown in FIG.
The ring-shaped magnet 57 is sandwiched between the pole piece 58 and the plate 59.
Voice coil 60 in the gap between
Are supported so as to be movable up and down.

FIG. 13 shows an enlarged view of the voice coil 60. The drive current corresponding to the audio signal is a power amplifier 5
When supplied to the voice coil 60 from 5, the voice coil 60 vibrates up and down according to Fleming's left-hand rule. Thereby, the diaphragm 61 vibrates, and a sound is generated.

A curve 62a in FIG.
It is a frequency characteristic of a sound pressure when driven by W. Further, the curves 62b and 62c are respectively the second harmonic distortion and the third harmonic distortion.
It is a frequency characteristic of harmonic distortion.

[0007]

However, in the above-described conventional audio device, when a high level audio signal is input, an excessive drive current is supplied to the speaker 56, which causes the sound to be distorted. have.

[0008]

In order to solve the above-mentioned problems, an audio device according to the invention of claim 1 comprises a power amplifier for amplifying an audio signal to drive a speaker, and an electronic volume adjusting means. , The key switch part that inputs the distortion level of the speaker, the storage part that stores the distortion level of the speaker that is input from the key switch part, the output signal of the power amplifier is converted to a digital signal, and the level and the memory of this digital signal are stored. And a control circuit for controlling the volume adjusting means so that the output of the speaker is not distorted by comparing the distortion levels stored in the unit.

In order to solve the above-mentioned problems, an audio device according to a second aspect of the present invention controls a power amplifier for amplifying an audio signal to drive a speaker, an electronic volume adjusting means, and a distortion level of the speaker. The input key switch section, the storage section that stores the distortion level of the speaker input from the key switch section, the detection unit that detects the level difference between the input audio signal and the output signal of the power amplifier, and the output of the power amplifier The signal is converted into a digital signal, and the volume adjustment means is controlled so that the speaker output is not distorted by comparing the level of this digital signal with the distortion level stored in the storage section. Adjust the volume so that the speaker output is not distorted based on the above level difference until it is converted to a digital signal It is characterized in that a control circuit for controlling the stage are provided.

In order to solve the above-mentioned problems, an audio apparatus according to a third aspect of the present invention amplifies an audio signal to drive a speaker, an electronic volume adjusting means, and an electronic sound quality adjusting. A circuit and a key switch part that inputs the frequency characteristics of the distortion level and sound pressure of the speaker,
The storage unit that stores the distortion level of the speaker and the frequency characteristic of the sound pressure input from the key switch unit, and the output signal of the power amplifier are converted into a digital signal, and the level of this digital signal and the distortion stored in the storage unit. By comparing the levels, the volume adjustment means is controlled so that the speaker output is not distorted, and the frequency characteristics of the sound pressure of the speaker are flattened based on the frequency characteristics of the sound pressure stored in the storage unit. A control circuit for controlling the sound quality adjustment circuit is provided.

[0011]

According to the first aspect of the present invention, there is provided a power amplifier for amplifying an audio signal to drive a speaker, an electronic volume control means, a key switch for inputting a distortion level of the speaker, and a key switch. By converting the output signal of the storage unit that stores the input distortion level of the speaker and the output signal of the power amplifier into a digital signal, and comparing the level of this digital signal and the distortion level stored in the storage unit, the output of the speaker is Since a control circuit for controlling the volume control means so as not to be distorted is provided, even if a high-level audio signal is input, an excessive drive current is less likely to be supplied to the speaker. This reduces sound distortion.

According to the structure of claim 2, the power amplifier for amplifying the audio signal to drive the speaker, the electronic volume adjusting means, the key switch section for inputting the distortion level of the speaker, and the key switch section A storage unit for storing the input distortion level of the speaker, a detecting means for detecting a level difference between the input audio signal and the output signal of the power amplifier, and converting the output signal of the power amplifier into a digital signal; And the distortion level stored in the storage unit are compared to control the volume adjusting means so that the output of the speaker is not distorted, and at the time until the output signal of the power amplifier is converted to a digital signal, Since it is equipped with a control circuit that controls the volume adjustment means so that the speaker output is not distorted based on the level difference of When the audio signal of high level is input, wherein in addition to the effect of claim 1, excessive drive current during the period until the output signal of the power amplifier is converted into a digital signal it is it is eliminated supplied to a speaker. This further reduces sound distortion.

According to the third aspect of the invention, the power amplifier for amplifying the audio signal to drive the speaker, the electronic volume adjusting means, the electronic sound quality adjusting circuit, the distortion level and the sound pressure of the speaker. A key switch unit for inputting frequency characteristics, a storage unit for storing frequency characteristics of the distortion level and sound pressure of the speaker input from the key switch unit,
By converting the output signal of the power amplifier into a digital signal and comparing the level of this digital signal with the distortion level stored in the storage section, the volume control means is controlled so that the speaker output is not distorted, and the storage section is also provided. And a control circuit for controlling the sound quality adjustment circuit so that the frequency characteristics of the sound pressure of the speaker are flattened based on the frequency characteristics of the sound pressure stored in the storage device.
Good sound quality can be obtained.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A first embodiment of the present invention will be described with reference to FIGS.
This will be described below.

As shown in FIG. 1, the audio device of this embodiment includes an electronic graphic equalizer 1 (electronic sound quality adjusting circuit), an electronic volume 2 (electronic volume adjusting means), a power amplifier 3, and a speaker 4. And control circuit 2
1 is comprised. The control circuit 21 is the speaker 4
The electronic graphic equalizer 1 and the electronic volume 2 are controlled so that a sound with less distortion is output from.

As shown in FIG. 3, the speaker 4 includes a ring-shaped magnet 31, a pole piece 32, and a plate 3.
3, voice coil 34, pickup coil 35, diaphragm 36, frame 37, connection terminal 38, lead wire 39 of voice coil 34 and pickup coil 35, damper 40, center cap 41, bobbin 42 and edge 43. It is configured. The magnet 31 is sandwiched between a pole piece 32 and a plate 33, and a voice coil 34 and a pickup coil 35 are supported in a gap between the pole piece 32 and the plate 33 so as to be vertically movable.

The pickup coil 35 is disposed coaxially with the voice coil 34, as shown in FIG. When the drive current corresponding to the audio signal is supplied from the power amplifier 3 to the voice coil 34, the voice coil 34 vibrates up and down according to Fleming's left-hand rule. Thereby, the diaphragm 36 vibrates, and a sound is generated. Also,
Due to the electromagnetic induction, a voltage corresponding to the drive current is generated across the pickup coil 35.

The control circuit 21 (FIG. 1) includes a pickup
An amplifier 5 that amplifies the voltage generated in the coil 35, a low-pass filter 9a that removes high-frequency noise components from the output signal of the amplifier 5, and a low-pass filter 9a.
Sample-and-hold circuit 10a for sampling the output signal of the above and holding the sampling voltage, and an A / D converter 12 for converting the sampling voltage into a digital signal
And electronic graphics based on this digital signal
A control microcomputer 8 for controlling the equalizer 1 and the electronic volume 2, a key switch section 15 for setting the electronic graphic equalizer 1 and the electronic volume 2, etc., a display section 16 for displaying volume and sound quality, and a crystal oscillation. It comprises a clock generation circuit 14 having a child 14a.

The A / D converter 12 includes a quantization circuit 12a for quantizing the sampling voltage and an encoding circuit 12b for encoding the quantized voltage. The reference clock output from the clock generation circuit 14 is the sample and hold circuit 10a and the quantization circuit 12
a, the encoding circuit 12b, and the control microcomputer 8.

As shown in FIG. 2, the control microcomputer 8 is mainly composed of a processing unit 17 including first to fourth arithmetic units 18a to 18d and first to fourth storage units 19a to 19d. There is.

The first storage section 19a stores the frequency characteristic of the sound pressure of the speaker 4. The second storage unit 19b stores the frequency characteristic of the distortion level of the speaker 4. Third storage unit 19
c stores the volume setting value of the electronic volume 2. The fourth storage unit 19d stores the sound quality setting value for each frequency band of the electronic graphic equalizer 1.

The first calculation unit 18a determines whether the operation level of the speaker 4 does not exceed the distortion level. The second calculation unit 18b calculates the amplification degree (or attenuation degree) for each frequency band of the electronic graphic equalizer 1 so that the frequency characteristic of the sound pressure of the speaker 4 becomes flat. The third calculation unit 18c controls the electronic volume 2 so that the speaker 4 is driven within the distortion level based on the determination result of the first calculation unit 18a. The fourth arithmetic unit 18d controls the electronic graphic equalizer 1 based on the calculation result of the second arithmetic unit 18b.

In the case of using the above-mentioned audio device, the frequency characteristics of the sound pressure and the distortion level of the speaker 4 are input by operating the key switch section 15, and the first and second storage sections 19a are respectively input. -Store in advance in 19b. The volume and sound quality are set according to preference by operating the key switch unit 15, and the set values are stored in the third and fourth storage units 19c and 19d, respectively.

The audio signal input to the electronic graphic equalizer 1 is amplified for each frequency band according to the above set value. The output of the graphic equalizer 1 is input to the power amplifier 3 via the electronic volume 2. The speaker 4 is driven by the power amplifier 3. The volume of the speaker 4 is set to the set value of the electronic volume 2.

The output of the speaker 4 can be monitored by the pickup coil 35. The voltage generated in the pickup coil 35 is amplified by the amplifier 5 and then the high-frequency noise component is removed by the low-pass filter 9a. The output of the low-pass filter 9a is sampled by the sample-and-hold circuit 10a, and the sampling voltage is held. The sampling voltage is converted into a digital signal by the A / D converter 12 and then input to the control microcomputer 8.

Processing unit 17 of control microcomputer 8
Is the electronic graphic equalizer 1 so that the output of the speaker 4 is not distorted based on this digital signal.
And control the electronic volume 2. That is, the level of the digital signal and the distortion level of the speaker 4 stored in the second storage unit 19b are compared by the first calculation unit 18a to determine whether the operation level of the speaker 4 does not exceed the distortion level. . Based on this result, the third calculation unit 18 is operated so that the speaker 4 is driven within the distortion level.
c controls the electronic volume 2. In addition, the amplification degree for each frequency band of the electronic graphic equalizer 1 is set by the fourth computing unit 18d so that the frequency characteristic of the sound pressure of the speaker 4 becomes flat, and then the desired value is set with this set value as a reference. It is controlled so as to become the sound quality set value.

A curve 29a in FIG. 5 shows the frequency characteristic of the sound pressure when the speaker 4 is driven at 1 W.
0 indicates the frequency characteristic of the sound pressure when the speaker 4 is driven at 1 W by using the conventional acoustic device.

By comparing the curves 29a and 30 with each other, it can be seen that the frequency characteristic of the sound pressure of the speaker 4 is significantly improved and the flat frequency characteristic is obtained in the acoustic device of this embodiment.

Curves 29b and 29c in FIG. 6 show the frequency characteristics of the second harmonic distortion and the third harmonic distortion when the speaker 4 is driven at 1 W, respectively.

The second embodiment of the present invention will be described below with reference to FIGS. 7 to 9. In addition,
For convenience of explanation, members having the same functions as the members shown in the drawings of the above-described embodiment are designated by the same reference numerals, and the description thereof will be omitted.

The difference between the audio device according to this embodiment and the audio device according to the above-mentioned embodiments lies in the control circuit 21a as shown in FIG. That is, in the control circuit 21a of the present embodiment, the amplifier 6 for amplifying the audio signal input to the electronic graphic equalizer 1 and the comparison amplifier 7 (detection means) for comparing the output of the amplifier 5 with the output of the amplifier 6 are described above. In addition to the control circuit 21, the electronic volume 2 is controlled based on the output of the comparison amplifier 7 until the monitor voltage extracted by the pickup coil 35 is converted into a digital signal.

The comparison amplifier 7 is specifically shown in FIG.
As shown in FIG. 7, mainly operational amplifiers 22 and 23 for amplifying the outputs of the amplifiers 5 and 6, an operational amplifier 24 for comparing their output levels, and a Schmitt circuit 25 for shaping the waveform of the output of the operational amplifier 24. It is configured.

The amplification degree of the operational amplifiers 22 and 23 is determined by the resistance R
₁ to R ₄ is set by, when the speaker 4 is driven by the distortion level below the output level of the operational amplifier 22 and 23 is set to be substantially equal. The outputs of the operational amplifiers 22 and 23 are
Connected to the inverting and non-inverting inputs.

The Schmitt circuit 25 includes two transistors 26 and 27, a capacitor C ₁ and resistors R _{5 to} R _9.
And a predetermined voltage V _CC is applied.

In the above configuration, when the speaker 4 is driven at a distortion level or less, the output of the operational amplifier 24 becomes almost zero, and the output of the Schmitt circuit 25 becomes low. On the other hand, when an excessive audio signal that exceeds the distortion level of the speaker 4 is input, the output of the operational amplifier 24 becomes positive, and the output of the Schmitt circuit 25 becomes high level. As described above, the comparison amplifier 7
By providing, it is possible to immediately determine whether an excessive audio signal exceeding the distortion level of the speaker 4 has been input to the electronic graphic equalizer 1.

The control microcomputer 8 prevents the output of the speaker 4 from being distorted based on the output of the comparison amplifier 7 until the monitor voltage extracted by the pickup coil 35 is converted into a digital signal.
The electronic volume 2 is controlled. As a result, an excessive drive current is not supplied to the speaker 4 until the monitor voltage is converted into a digital signal, so that the output of the speaker 4 is less likely to be distorted.

When the control microcomputer 8 is provided with an analog input port, it is possible to use the comparison amplifier 7 which outputs a voltage according to the output difference between the amplifiers 5 and 6. According to the comparison amplifier 7 as described above, it is possible not only to immediately determine whether an excessive audio signal exceeding the distortion level of the speaker 4 has been input, but also to determine to what extent an excessive audio signal has been input. it can. This allows
Since the electronic volume 2 can be finely controlled, it is possible to avoid a sudden change in volume near the distortion level.

Specifically, the comparison amplifier 7 includes a buffer circuit 28 instead of the Schmitt circuit 25 (FIG. 8) as shown in FIG. 9, for example. Buffer circuit 28, for example, a transistor 28a, which consists of a capacitor C _2, resistors R ₁₀ · R _11, a predetermined voltage V _CC is applied.

The third embodiment of the present invention will be described below with reference to FIG. For convenience of explanation, members having the same functions as those shown in the drawings of the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The difference between the audio device of this embodiment and the audio device of the above-described embodiment is that, as shown in FIG.
It is in. That is, the control circuit 21b of this embodiment has a configuration in which a low-pass filter 9b for converting the output of the amplifier 6 into a digital signal and a sample and hold circuit 10b are added to the control circuit 21a.

The sample and hold circuits 10a and 1
Multiplex circuit 1 for multiplexing the output of 0b
1 is provided before the A / D converter 12, and a digital signal processing circuit 13 is provided after the A / D converter 12 in order to adjust the timing of the digital signal.

In this embodiment, the pickup coil 35
Since the input voltage of the audio signal is monitored in addition to the monitor voltage of the speaker 4, it is possible to more reliably determine whether the operation level of the speaker 4 is appropriate.

In the above embodiments, the dynamic type (FIG. 3) is given as an example of the speaker 4, but a condenser type may be used. In this case, in order to detect the magnitude of the output signal, a sub diaphragm may be provided on the main diaphragm and a change in capacitance between the sub diaphragm and the fixed electrode may be detected.

The present invention can also be applied to the case where headphones are used instead of the speaker 4.

[0045]

As described above, the audio apparatus according to the present invention inputs the power amplifier for amplifying the audio signal to drive the speaker, the electronic volume adjusting means, and the distortion level of the speaker. A key switch section, a storage section for storing the distortion level of the speaker input from the key switch section, and a conversion of the output signal of the power amplifier into a digital signal, and the level of this digital signal and the distortion level stored in the storage section. By comparing with the control circuit that controls the volume adjusting means so that the speaker output is not distorted, an excessive drive current is supplied to the speaker even if a high-level audio signal is input. It gets harder. This has the effect of reducing the distortion of the sound.

As described above, the audio apparatus according to the second aspect of the present invention includes the power amplifier for amplifying the audio signal to drive the speaker, the electronic volume adjusting means, and the key switch for inputting the distortion level of the speaker. Section, a storage section that stores the distortion level of the speaker input from the key switch section, detection means that detects the level difference between the input audio signal and the output signal of the power amplifier, and the output signal of the power amplifier as a digital signal. The output signal of the power amplifier is converted into a digital signal while controlling the volume control means so that the speaker output is not distorted by comparing the level of this digital signal with the distortion level stored in the storage unit. During the period until it is controlled, the volume control means is controlled so that the speaker output is not distorted based on the above level difference. Since a control circuit is provided, when a high-level audio signal is input, an excessive drive current may be supplied to the speaker during the period until the output signal of the power amplifier is converted into a digital signal. Disappear. This has the effect of further reducing the distortion of the sound.

In order to solve the above problems, an audio device according to a third aspect of the present invention amplifies an audio signal to drive a speaker, an electronic volume adjusting means, and an electronic sound quality adjusting. A circuit and a key switch part that inputs the frequency characteristics of the distortion level and sound pressure of the speaker,
A storage unit that stores the distortion level of the speaker and the frequency characteristics of the sound pressure input from the key switch unit, and converts the output signal of the power amplifier into a digital signal, and outputs the level of the digital signal and the distortion stored in the storage unit. By comparing the levels, the volume adjustment means is controlled so that the speaker output is not distorted, and the frequency characteristics of the sound pressure of the speaker are flattened based on the frequency characteristics of the sound pressure stored in the storage unit. Since the control circuit for controlling the sound quality adjusting circuit is provided, the distortion of the sound is reduced and good sound quality can be obtained.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention and is a block diagram showing a schematic configuration of an audio device.

FIG. 2 is a block diagram showing a schematic configuration of a control microcomputer of FIG. 1;

FIG. 3 is a vertical cross-sectional view showing a schematic configuration of the speaker of FIG.

FIG. 4 is an explanatory diagram of a voice coil and a pickup coil of FIG. 3;

5 is a graph showing frequency characteristics of sound pressure when the speaker of FIG. 3 is driven by the audio device of FIG. 1 and frequency characteristics of sound pressure when this speaker is driven by the conventional audio device of FIG. Is.

6 is a graph showing frequency characteristics of sound pressure and frequency characteristics of second harmonic distortion and third harmonic distortion when the speaker of FIG. 3 is driven by the acoustic device of FIG. 1;

FIG. 7 shows a second embodiment of the present invention and is a block diagram showing a schematic configuration of an audio device.

FIG. 8 is a circuit diagram showing a specific example of the comparison amplifier of FIG.

9 is a circuit diagram showing another specific example of the comparison amplifier of FIG. 7. FIG.

FIG. 10 shows a third embodiment of the present invention and is a block diagram showing a schematic configuration of an audio device.

FIG. 11 is a block diagram showing a schematic configuration of a conventional audio device.

12 is a vertical cross-sectional view showing a schematic configuration of the speaker of FIG.

13 is an explanatory diagram of the voice coil of FIG.

14 is a graph showing frequency characteristics of sound pressure and frequency characteristics of second harmonic distortion and third harmonic distortion when the speaker of FIG. 12 is driven by the acoustic device of FIG.

[Explanation of symbols]

1 electronic graphic equalizer (sound quality adjustment circuit) 2 electronic volume (volume adjustment means) 3 power amplifier 4 speaker 5 amplifier 6 amplifier 7 comparison amplifier (detection means) 8 control microcomputer 15 key switch section 19a first storage section 19b second Storage unit 19c Third storage unit 19d Fourth storage unit 34 Voice coil 35 Pickup coil

Claims (3)

(57) [Claims] 1. A power amplifier for amplifying an audio signal to drive a speaker, an electronic volume adjusting means, a key switch section for inputting a distortion level of the speaker, and a distortion level of the speaker input from the key switch section. The volume is adjusted so that the output of the speaker is not distorted by converting the output signal of the power amplifier and the storage unit that stores the signal into a digital signal and comparing the level of this digital signal and the distortion level stored in the storage unit. And a control circuit for controlling the means. 2. A power amplifier for amplifying an audio signal to drive a speaker, an electronic volume adjusting means, a key switch section for inputting a distortion level of the speaker, and a distortion level of the speaker input from the key switch section. , A detecting means for detecting the level difference between the input audio signal and the output signal of the power amplifier, and converting the output signal of the power amplifier into a digital signal, and storing the level of the digital signal and the storage section By comparing the distortion level that is being controlled, the volume adjusting means is controlled so that the output of the speaker is not distorted, and based on the above level difference until the output signal of the power amplifier is converted to a digital signal. A sound characterized by comprising a control circuit for controlling the volume adjusting means so that the output of the speaker is not distorted. Apparatus. 3. A power amplifier for amplifying an audio signal to drive a speaker, an electronic volume adjusting means, an electronic sound quality adjusting circuit, and a key switch for inputting the distortion level and frequency characteristics of sound pressure of the speaker. Section, a memory section that stores the frequency characteristics of the distortion level and sound pressure of the speaker input from the key switch section, and the output signal of the power amplifier is converted into a digital signal, and the level of this digital signal and the memory section are stored. The volume control means is controlled so that the speaker output is not distorted by comparing the distortion levels, and the frequency characteristics of the sound pressure of the speaker are flattened based on the frequency characteristics of the sound pressure stored in the storage unit. And a control circuit for controlling the sound quality adjustment circuit.