JPH089990Y2 - Range expander - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a sound range expanding device for expanding an occupied band of an audio signal in an audio reproducing device or the like.

[Conventional technology]

Conventionally, in an audio reproducing apparatus or the like, an input signal is appropriately amplified and then output as an audio signal.

[Problems to be solved by the invention]

A conventional audio device or the like reproduces an input signal without modifying it, so that there is a shortage of a high range or a deep bass signal depending on the type of the input signal.

This is because the raw sound before being converted into an audio signal, etc., contains sounds of various frequencies, including treble sounds regardless of whether they are audible or inaudible. ing. However, the audio signal does not include the frequency of the raw sound due to the frequency characteristics of the microphone that inputs the raw sound and the recording means. Since the conventional audio device and the like only amplify and output such an audio signal, they cannot supplement the sound in the treble range. For this reason,
There is a problem that it is not possible to obtain a sound corresponding to the high range of raw sound.

Similarly, regarding the low frequency range, the frequency of the low frequency range cannot be supplemented to the audio signal regardless of the audible region or the inaudible region. Therefore, there is a problem that it is not possible to obtain a sound corresponding to the low tone range of the raw sound.

Therefore, in order to solve the above problems, the present invention extracts a specific frequency band from an input audio signal, generates a second overtone or a half overtone, and converts it into the original sound. An object of the present invention is to obtain a range expanding device that replenishes an audio signal and reproduces it to bring it closer to a raw sound before audio signal conversion.

[Means for Solving the Problem] A range expanding device according to the present invention includes: a first bandpass filter for extracting and outputting a plurality of band signals including a _first frequency f ₁ from an input audio signal; By multiplying the output signals of the bandpass filters of
Center and the frequency converter for frequency-converting a plurality of signals, from the multiplied output signal of the frequency converter, a second frequency nf ₁ including a second frequency nf ₁ constant n times the first frequency f ₁ A second bandpass filter for extracting a band signal of the following, and an adder for adding the output of the second bandpass filter to the input audio signal.

[Operation] In the present invention, the first band pass filter extracts a plurality of band signals including the first frequency f ₁ from the input audio signal.

Next, the frequency converter multiplies the output signals (composed of a plurality of frequency signals) of the first band pass filter by each other, so that, for example, when n = 2, the first frequency
The signal is converted into a signal including a band signal centered at a frequency twice f ₁ .

Next, the second bandpass filter extracts a band signal centered on a frequency twice the first frequency f ₁ (when n = 2) from the output signal of the frequency converter.

Then, the adder adds the output of the second bandpass filter to the input audio signal,
The treble range where the input audio signal could not be reproduced is expanded.

[Example of device]

An embodiment of this invention will be described below. FIG. 1 is a block diagram of a treble range expanding device according to an embodiment. In the figure, (1) is a buffer amplifier, and (2) is a narrow band pass filter having a center frequency of f _{1 of the} middle and high band signals.
(3) is a frequency converter, and in this embodiment, a four-quadrant multiplier (31) is used. (4) shows a narrow bandpass filter having a center frequency of 2f ₁ , and (5) shows an adder.

Next, the operation of the embodiment shown in FIG. 1 will be described. In FIG. 1, after the input signal is amplified by the buffer amplifier (1), f ₁ →
A bandpass filter (2) having a center frequency of θ ₁ obtains an output represented by f (θ) = Acos θ ₁ + Bcos θ ₂ . However, A cos .theta ₁ is an arbitrary frequency signals mid-high range on which to base the generation of the desired signal is located in the high range (signal 2 [Theta] ₁ component described below), Bcosθ ₂ is narrow extracts the theta ₁ component A component that cannot be removed by using the band pass filter (2), that is, the band pass filter (2)
Unnecessary frequency f ₂ (f ₂ ≠ f ₁ ) within the finite predetermined bandwidth of
Signal. The amplitude level is A >> B. The output of the bandpass filter (2) is a multiplier (31) by ^{f 2 (θ) = A 2} cos 2 θ 1 + 2ABcosθ 1 cosθ 2 + B 2 cosθ 2 = A 2/2 · (cos2θ 1 +1) + 2AB {cos ( θ ₁ + θ
_{2) + cos (θ 1 -θ} 2)} + B become _{^{2/2 · (cos2θ 2 +1}} ). In this state, in addition to the desired signal 2θ ₁ , 2θ ₂ ,
Since the components of θ ₁ + θ ₂ and θ ₁ −θ ₂ are included, as a result, in addition to 2f ₁ corresponding to the desired signal 2θ ₁ , what is regarded as an unnecessary signal, that is, 2f corresponding to the second harmonic 2θ _{2. 2} , a signal having a frequency of f ₁ + f ₂ , f ₁ −f ₂ corresponding to the beat component θ ₁ + θ ₂ or θ ₁ −θ ₂ of the mid-high range signal θ ₁ and the unnecessary signal θ ₂ , and a DC component ^{A 2/2 + B 2/} 2 are derived. Therefore, a band-pass filter centered at _{2f 1 → 2θ 1 (4)} , to remove these unwanted signals, resulting F (θ) = obtain desired signal that ^{(A 2/2) · cos2θ} 1. If this technical idea is used, for example, the bandpass filter (2) is provided with a plurality of values having different center frequencies θ ₁ , and the center frequencies θ ₁ are different from each other.
An adder (5) is used to add the output signal of the band-pass filter (4) having the double-pass frequency with the band-pass characteristic and the input signal.
It is configured to add in. The output of the adder (5) is
Each desired signal 2f ₁ corresponding to 2 times f ₁ corresponding to each 2θ ₁ is added, and as a result, the treble range signal for any plurality of mid-high range of the input signal is included. That is clear.

FIG. 2 is a block diagram of a treble range expanding device according to another embodiment of the present invention, and FIG. 3 is an operation waveform diagram thereof. First
The same reference numerals in the drawings denote the same things.
(3A) is a frequency converter, which is composed of a positive phase amplifier (32), an inverting amplifier (33), and diodes (D1) and (D2).

Next, the operation of the embodiment shown in FIG. 2 will be described. The input signal, after being amplified by the buffer amplifier (1), has the waveform of FIG. 3 (A) by the bandpass filter (2) whose center frequency is f ₁ . The outputs of the amplifiers (32) and (33) have mutually opposite phases, and the detection diodes (D1) and (D2) obtain the waveform of FIG. 3 (B). The output waveform of the adder (5) is 2f
_An unnecessary signal component is removed by a bandpass filter (4) having a center frequency of ₁ and is an output signal of the bandpass filter (2) as shown in FIG. 3 (C).
The signal waveform has a frequency twice as high as the frequency. Next, the signal and the input signal are added to the adder (5) and combined. The output of the adder (5) contains the high frequency range signal by the above-described synthesis.

FIG. 4 is a block diagram of a low temperature region expanding device according to another embodiment of the present invention, and FIG. 5 is an operation waveform diagram thereof. First
The same reference numerals as those used in the drawings indicate the same elements.
(2A) is a bandpass filter whose center frequency is f _{1 of the} low temperature signal. (3B) is a frequency converter, which is a positive phase amplifier (34), an inverting amplifier (35), a 1 / n frequency divider (36), switching elements (37), (38), an adder (39), and a diode. It is composed of (D3) to (D6). And (4
A) shows a bandpass filter whose center frequency is f _1/2 .

Next, the operation of the embodiment shown in FIG. 4 will be described. The input signal is amplified by the buffer amplifier (1) and then the band pass filter (2
The waveform shown in FIG. 5 (A) is obtained by A). Amplifier (3
Since 4) and (35) have opposite phases to each other, the signals detected by the diodes (D3) to (D6) following them have the signal waveforms of FIGS. 5 (B) and 5 (C), respectively. The output of the 1/2 frequency divider (36) following the bandpass filter (2A) has the waveforms shown in FIGS. 5 (D) and 5 (E). The switching elements (37) and (38) are alternately controlled by this signal, and the signals (F) and (G) are obtained from the signals shown in FIGS. 5 (B) and 5 (C). Then, they are added by the adder (39) to obtain the signal of FIG. 5 (H). Bandpass filter (4 this signal having a center frequency f _0/2
The unnecessary signal component is removed by A), and the signal shown in FIG. 5 (I) is obtained. The output of the bandpass filter (4A) is a signal converted into a signal in which the frequency f ₁ of an arbitrary bass signal is divided by 1/2. In addition, the bandpass filter (2A) has a plurality of different values of the center frequency f ₁ , f ₁₁ , f ₁₂ ,
f ₁₃ ... to have a respective _{f 11, f 12, f 13} ... and the output signal of the band-pass filter (4A) which gave a band-pass characteristic on the frequency of 1/2 of the adder and the input signal ( With the configuration of adding to 5), it becomes possible to reproduce the deep bass range signals of f ₁₁ , f ₁₂ , f _13, ... Which are half the frequencies of the bass range signals. It is needless to say that the frequency converter in this invention is not limited to the one shown in the above-mentioned embodiment, but can be modified appropriately. Further, the 1/2 divider (36) is an example of the case of 1/2 division, but it can be replaced with a divider corresponding to the desired division.

[Effect of device]

As described above, according to the present invention, a signal in a predetermined frequency band is extracted from an input sound signal, and the output signals are multiplied by each other to perform frequency conversion into a signal in a frequency band that is a constant multiple of the output signal. The effect of widening the treble range is obtained by removing unnecessary signal components from the frequency-converted output signal and adding them to the input sound signal.

Also, after obtaining a pulsating signal which is a full-wave rectified output signal from the first bandpass filter, and after the second bandpass filter removes unnecessary signal components from the pulsating signal which is the output signal of the frequency converter, Since the input sound signal and the output signal from which this unnecessary component has been removed are combined, it is possible to obtain the effect of expanding the treble range with a simple configuration.

Further, the positive and negative components of the output signal from the first bandpass filter are full-wave rectified, and both of the full-wave rectified pulsating signals are set to 1 / n times the frequency of the output signal from the first bandpass filter. (N is an integer of 2 or more), and the output signal obtained by combining both divided signals is output to the second bandpass filter to remove unnecessary signal components and then remove unnecessary signal components. By synthesizing the output signal of the frequency converter and the input sound signal, the low frequency range is expanded, so that the effect of obtaining deep bass can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a treble range expanding device according to an embodiment of the present invention, and FIGS. 2 and 3 are block diagrams of a treble range expanding device according to another embodiment of the present invention and operation waveform diagrams thereof.
4 and 5 are a block diagram and an operation waveform diagram of a bass expansion device according to another embodiment of the present invention. (2): 1st bandpass filter (3): Frequency converter (4): 2nd bandpass filter (5): Adder In addition, the same code | symbol shows the same or corresponding part in the figure.

Claims (4)

[Scope of utility model registration request] 1. A first band-pass filter for extracting a plurality of band signals including a _first frequency f ₁ from an input audio signal and outputting the band signals, and the output signals of the first band-pass filter are multiplied. A frequency converter for frequency-converting into a plurality of signals including a second frequency nf ₁ that is a constant n times the first frequency f ₁ (n is an integer of 2 or more), and multiplication of the frequency converter A second bandpass filter for extracting a band signal centered on the second frequency nf ₁ from the output signal thus obtained, and an addition for adding the output of the second bandpass filter to the input audio signal. Range expander, which is equipped with 2. The frequency converter inputs the output signal from the first band pass filter in parallel and performs full-wave rectification to extract a band signal centered on the second frequency nf _1. A range expanding device according to claim 1, wherein the utility model registration is output to the second band pass filter. 3. The frequency converter full-wave rectifies the positive and negative components of the output signal from the first band-pass filter, respectively, and pulsates the positive and negative pulsating signals of the full-wave rectified signal, An output obtained by dividing the frequency of the output signal of the first bandpass filter into positive and negative timing determined by the output of a frequency divider that divides the frequency by 1 / n, and combining the divided positive and negative signals. The range enlarging device according to claim 1, wherein the signal is output to the second bandpass filter. 4. The range expanding device according to claim 1, 2, or 3, wherein the constant n is n = 2.