JP4348936B2 - Portable terminal device and method for increasing output volume thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a portable terminal device having a speaker for voice / sound output and a method for increasing output volume from the speaker.
[0002]
[Prior art]
In recent years, mobile terminal devices such as mobile phones are required to output sounds in a frequency band of less than 1 kHz, such as human voice and tone (sound), from built-in speakers (microspeakers). However, in response to demands for reducing the size and weight of portable terminal devices and reducing power consumption, the speakers themselves (diaphragm) are also reduced in size, making it difficult to increase the sound pressure below 1 kHz and driving the speakers. Therefore, it is difficult to increase the maximum output voltage supplied to the amplifier, and it is increasingly difficult to increase the volume output from the speaker.
[0003]
On the other hand, a technique has been proposed in which a low frequency component can be reinforced in the sense of hearing of a listener (user) by adding a harmonic component higher than the audible frequency to a musical sound signal (for example, Patent Document 1). reference).
[0004]
[Patent Document 1]
JP-A-8-123421 (page 1-2, FIG. 1-2)
[0005]
[Problems to be solved by the invention]
In the above-described conventional portable terminal device, it is difficult to increase the output volume because of restrictions on the structure (size) and power supply voltage (amplifier maximum output voltage) for the built-in speaker (micro speaker).
[0006]
The object of the present invention is to provide a sound output from a speaker without increasing the maximum output voltage of an amplifier by using a characteristic configuration and method in a technique for reinforcing volume by adding a harmonic component to an original signal, In particular, it is an object of the present invention to provide a portable terminal device that enables a listener to easily recognize sound in a frequency band of less than 1 kHz, and a method for increasing the output volume thereof.
[0007]
[Means for Solving the Problems]
An output volume increasing method according to claim 1 of the present invention is the method of increasing the output volume from a speaker in a portable terminal device having a speaker for voice / sound output. the components, the original signal output created by Fourier transform processing and modulation processing, the inverse fast Fourier transform processing to a time domain signal after adding the odd-number order harmonic components in the original signal and the frequency domain A step of supplying a signal obtained by adding the odd harmonic component to the original signal returned to the time domain and outputting the signal as an audible sound.
[0008]
The output sound volume increasing method according to claim 2 of the present invention is characterized in that, in the output sound volume increasing method according to claim 1, the odd harmonic component is a third harmonic component.
[0009]
An output volume increasing method according to a third aspect of the present invention is the output volume increasing method according to the first aspect, wherein the odd harmonic component is an odd harmonic component of a plurality of different orders.
[0010]
The output volume increasing method according to claim 4 of the present invention is the output volume increasing method according to claim 1 or 2, wherein the intensity ratio between the original signal and the added odd harmonic component is set to 1: 1. It is characterized by.
[0011]
An output volume increasing method according to a fifth aspect of the present invention is the output volume increasing method according to the first, second or third aspect, wherein the intensity ratio between the original signal and each of all the odd harmonic components to be added is set. , The intensity after addition can be arbitrarily changed under the condition that the intensity is the same as the intensity of the original signal.
[0012]
According to a sixth aspect of the present invention, there is provided a portable terminal device having a speaker for voice / sound output, and a fast Fourier transforming a source signal for output to the speaker into a signal in a frequency domain by performing a fast Fourier transform process. A conversion means; a modulation means for branching the output signal of the fast Fourier transform means to generate an odd-order harmonic component of a predetermined order; an output signal of the fast Fourier transform means; and an output signal of the modulation means. An intensity changing / adding means for adding in accordance with a predetermined intensity ratio, an inverse fast Fourier transform means for returning the output signal of the intensity changing / adding means to a signal in the time domain by performing an inverse fast Fourier transform process, and an inverse fast Fourier transform means Signal conversion / amplification means for converting and amplifying the output signal into a signal capable of outputting audible sound from the speaker and supplying the signal to the speaker.
[0013]
The mobile terminal device according to claim 7 of the present invention is the mobile terminal device according to claim 6, wherein the modulation means generates a third-order harmonic component as the odd-order harmonic component.
[0014]
A mobile terminal device according to an eighth aspect of the present invention is the mobile terminal device according to the sixth aspect, wherein a plurality of the modulation means are provided corresponding to a plurality of odd-order harmonic components of different orders specified in advance, The intensity changing / adding means adds the output signal of the fast Fourier transform means and the output signals of the plurality of modulating means according to a predetermined intensity ratio.
[0015]
A mobile terminal device according to claim 9 of the present invention is the mobile terminal device according to claim 6 or 7, wherein the intensity changing / adding means includes an output signal of the fast Fourier transform means, an output signal of the modulation means, It is characterized by adding the intensity ratio of 1: 1 as 1: 1.
[0016]
The mobile terminal device according to claim 10 of the present invention is the mobile terminal device according to claim 6, 7 or 8, wherein all the modulations that the intensity changing / adding means adds to the output signal of the fast Fourier transform means The intensity ratio of each means to the output signal can be arbitrarily changed under the condition that the intensity after addition is the same as the intensity of the original signal.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
First, the outline of the present invention will be described. The mobile terminal device according to the present invention adds a harmonic component to the original signal (fundamental frequency), so that the volume (audible volume) output from the mobile terminal device built-in microspeaker without increasing the maximum output voltage of the amplifier. It is a portable terminal device that can raise
[0018]
More specifically, the mobile terminal apparatus buffers a digital signal such as a time-domain audio signal or acoustic signal sent from the demodulator for an arbitrary number of seconds, and then performs FFT (Fast Fourier Transform: high speed) at an arbitrary score. (Fourier transform) processing is performed to convert the signal into a frequency domain signal. The converted signal is divided into two (or two or more) signals, one of which is subjected to only signal strength change processing as an original signal, and the rest is a harmonic component for each predetermined order (odd number: for example, third order, fifth order). Creation processing (modulation processing) and signal intensity change processing are performed. Signal components that have gone out of band due to modulation are deleted. The original signal (basic frequency component signal) after the signal strength change process and its harmonic component signal are adjusted so that they become signals of the same time on the time series, then added, and the frequency domain signal of the addition result is subjected to FFT processing The inverse FFT processing is executed with the same number of points as the converted points to convert it into a time domain signal and further into an analog signal. The analog signal is amplified to an arbitrary amplitude and then output from a speaker (micro speaker).
[0019]
Next, embodiments of the present invention will be described in detail with reference to the drawings.
[0020]
FIG. 1 is a block diagram showing an embodiment of the present invention, and shows only a part related to the present invention in a portable terminal device.
[0021]
In FIG. 1, a mobile terminal device 1 of this example is used as a mobile phone that is a mobile station of a mobile communication system. As a means for outputting voice and acoustic information to a user, a fast Fourier transform processing unit (FFT) 10 and , Modulator 21, signal intensity changing units 30 and 31, adding unit 40, inverse fast Fourier transform processing unit (IFFT) 50, digital / analog converter (DAC) 60, variable amplifier 70, and speaker 80. And have. Although not shown, the mobile terminal device 1 is a radio that modulates and demodulates a voice signal by transmitting and receiving a radio signal between a base station and a voice input unit that includes a microphone and inputs voice information from a user. An operation display unit for inputting and displaying character and graphic information to the user, and a control unit for controlling the entire apparatus.
[0022]
The fast Fourier transform processing unit (FFT) 10 is connected to a radio unit demodulator (not shown), and fast Fourier transform processing is performed on a signal (digital audio signal: PCM (Pulse-Code Modulation) signal) output from the demodulator. (FFT: Fast Fourier Transform) is executed, and the signal after the FFT processing is divided into two and sent to the modulator 21 and the signal strength changing unit 30, respectively.
[0023]
The modulator 21 modulates the frequency of the signal output from the fast Fourier transform processing unit 10 to an odd multiple (here, tripled), and then sends the modulated signal to the signal strength changing unit 31.
[0024]
The signal strength changing unit 30 changes the strength of the signal output from the fast Fourier transform processing unit 10 (here, 0.5 times) and then sends the signal strength to the adding unit 40.
[0025]
The signal strength changing unit 31 changes the strength of the signal output from the modulator 21 (here, 0.5 times) and then sends the signal strength to the adding unit 40.
[0026]
The adding unit 40 adds the output signal of the signal strength changing unit 30 and the output signal of the signal strength changing unit 31 and then sends the sum to the inverse fast Fourier transform processing unit (IFFT) 50.
[0027]
The inverse fast Fourier transform processing unit (IFFT) 50 performs inverse FFT processing on the signal output from the adding unit 40 and sends the processed signal to the digital / analog converter (DAC) 60.
[0028]
The digital / analog converter (DAC) 60 converts the digital signal output from the inverse fast Fourier transform processing unit 50 into an analog signal and then sends the analog signal to the variable amplifier 70.
[0029]
The variable amplifier 70 amplifies the signal output from the digital / analog converter 60 with an arbitrary amplification factor and then sends the amplified signal to the speaker 80.
[0030]
The speaker 80 emits sound and sound corresponding to the input signal and can be listened to by the user.
[0031]
Next, the operation of this embodiment will be described in more detail.
[0032]
The fast Fourier transform processing unit (FFT) 10 buffers a digital signal (PCM signal) sent from a demodulator (not shown) for an arbitrary number of seconds (for example, 20 ms), and then executes an FFT process at an arbitrary number of points. Convert the signal to a frequency domain signal. The score here corresponds to the accuracy when the input signal is converted into the frequency domain by FFT processing. For example, when 256-point FFT is performed on an input signal with a sampling frequency of 8 kHz, the frequency distribution of the input signal can be obtained in increments of (4000/256) Hz. Alternatively, when a 128-point FFT is performed on an input signal with a sampling frequency of 16 kHz, the frequency distribution of the input signal can be obtained in increments of (8000/128) Hz. In general, there are many 128, 256, 512, 1024 and 2048 points to be selected (the number of points suitable for FFT processing). In this example, it is 128 points. The signal converted into the frequency domain signal is sent to the modulator 21 and the signal strength changing unit 30.
[0033]
The modulator 21 generates a harmonic component (third harmonic) of the original signal by modulating the received signal so that the frequency is tripled, and sends the processed signal to the signal strength changing unit 31. Signal components that have gone out of band due to modulation are deleted. The reason why the signal is tripled is that the processed signal is the lowest-order harmonic component that hardly discomforts humans (users).
[0034]
The signal strength changing unit 30 and the signal strength changing unit 31 each halve the intensity of the input signal and send it to the adding unit 40. The reason for halving is to prevent the signal intensity from exceeding the digital maximum value when adding two signals by the adder 40.
[0035]
The adding unit 40 adjusts the output signals of the signal strength changing unit 30 and the signal strength changing unit 31 so as to be signals of the same time in time series, and then adds them to the inverse fast Fourier transform processing unit (IFFT) 50. send.
[0036]
The inverse fast Fourier transform processing unit 50 performs an inverse FFT process on the input frequency domain signal with the same score (128 points in this example) as the score performed by the fast Fourier transform processing unit 10, and performs a time domain signal. And sent to a digital / analog converter (DAC) 60.
[0037]
The signal output from the inverse fast Fourier transform processing unit 50 is converted into an analog signal by a digital / analog converter (DAC) 60, amplified to an arbitrary amplitude by a variable amplifier 70, and then output as an audible sound from the speaker 10. The
[0038]
Thus, in the present embodiment (first embodiment), the input signal (original signal) and the third harmonic component added to the input signal have an intensity ratio of 1: 1 (0.5 : 0.5), and the added intensity is the same as the input signal intensity (1 = 0.5 + 0.5).
[0039]
Next, a modification of the first embodiment will be described.
[0040]
The amplification factor of the signal strength changing unit 30 and the amplification factor of the signal strength changing unit 31 shown in FIG. 1 may be changed to arbitrary amplification factors as long as the condition that the sum of the two amplification factors is “1” is satisfied. (For example, 0.7 and 0.3). Thereby, the intensity | strength of a harmonic component can be adjusted arbitrarily.
[0041]
Further, the modulation amount of the modulator 21 may be changed to an arbitrary modulation amount (for example, 5 times) as long as the condition of an odd multiple is satisfied.
[0042]
Next, another embodiment (second embodiment) of the present invention will be described with reference to FIG.
[0043]
The portable terminal device 2 of the second embodiment shown in FIG. 2 is different from the portable terminal device 1 of the first embodiment shown in FIG. 1 in that a fast Fourier transform processing unit (FFT) 10 and an adding unit 40 In the meantime, the modulator 22 and the signal strength changing unit 32 connected in series with each other are added, and the amplification factor of the signal strength changing unit 31 is changed to 0.25.
[0044]
The modulator 22 modulates the frequency of the signal output from the fast Fourier transform processing unit 10 by 5 times and then sends the signal to the signal strength changing unit 32.
[0045]
The signal strength changing unit 32 multiplies the signal output from the modulator 22 by 0.25 and sends the signal to the adding unit 40. Thereby, the combination freedom degree of a harmonic component can be raised.
[0046]
The functions and operations of other parts are the same as those of the mobile terminal device 1 shown in FIG.
[0047]
Next, a modification of the second embodiment will be described.
[0048]
In FIG. 2, the amplification factor of each of the signal intensity changing units 30, 31, and 32 may be changed to any amplification factor as long as the condition that the total of the amplification factors of the three members is “1” (for example, 0.5, 0.3 and 0.2). Thereby, the intensity | strength of a harmonic component can be adjusted arbitrarily.
[0049]
Further, although the number of sets of modulators and signal strength changing units added in FIG. 2 is one, any number of sets may be added. However, the modulation rate must be an arbitrary odd multiple (3 times, 5 times, 7 times,...), And the sum of the intensity amplification factors of all the signal intensity changing units must be “1”.
[0050]
In each of the above-described embodiments, the mobile terminal device is a mobile phone. However, the present invention is not limited to this, and any mobile terminal device having a speaker for voice / sound output can be applied. is there. For example, a radio, a recording / reproducing machine, or a song reproducing machine can be considered.
[0051]
【The invention's effect】
As described above, according to the present invention, since the harmonic component of the output signal is added to the original signal, it is possible to increase the signal intensity before amplification by the amplifier, and from the speaker without increasing the maximum output voltage of the amplifier. It is possible to increase the volume of the output sound. Also, even when a micro speaker that cannot increase the sound pressure below 1 kHz is used as the speaker, the sound component of 1 kHz or more that can increase the sound pressure increases even with the micro speaker, so that it is difficult for the listener to recognize with the conventional technology. In addition, it becomes possible for the listener to easily recognize a sound (basic frequency) of less than 1 kHz.
[Brief description of the drawings]
FIG. 1 is a block configuration diagram showing an embodiment of the present invention.
FIG. 2 is a block diagram showing another embodiment of the present invention.
[Explanation of symbols]
1, 2 Mobile terminal device 10 Fast Fourier transform processing unit (FFT)
21, 22 Modulator 30, 31, 32 Signal intensity changing unit 40 Adding unit 50 Inverse fast Fourier transform processing unit (IFFT)
60 Digital / analog converter (DAC)
70 Variable amplifier 80 Speaker

Claims (10)

In a method for increasing output volume from a speaker in a portable terminal device having a speaker for voice / sound output,
The odd-order harmonic components of the output based on signals for the speaker, the original signal output created by the fast Fourier transform processing and modulation processing, the sum of the odd-number order harmonic components in the original signal and the frequency domain A reverse fast Fourier transform process is performed later to return to the time domain signal, and a signal obtained by adding the odd harmonic component to the original signal returned to the time domain is supplied to the speaker and output as an audible sound. Output volume increase method.   2. The output volume increasing method according to claim 1, wherein the odd harmonic component is a third harmonic component.   2. The output volume increasing method according to claim 1, wherein the odd harmonic component is an odd harmonic component of a plurality of different orders.   3. The output volume increasing method according to claim 1, wherein an intensity ratio between the original signal and the odd harmonic component to be added is set to 1: 1.   The intensity ratio between the original signal and each of the added odd harmonic components can be arbitrarily changed under the condition that the intensity after addition is the same as the intensity of the original signal. 4. The output volume increasing method according to claim 1, 2, or 3. In a portable terminal device having a speaker for voice / sound output,
Fast Fourier transform means for fast Fourier transform processing the original signal for output to the speaker and transforming it into a frequency domain signal;
A modulation means for branching and inputting an output signal of the fast Fourier transform means to generate odd harmonic components of a predetermined order;
Intensity changing / adding means for adding the output signal of the fast Fourier transform means and the output signal of the modulating means in accordance with a predetermined intensity ratio;
An inverse fast Fourier transform means for performing an inverse fast Fourier transform process on the output signal of the intensity changing / adding means and returning the signal to a time domain signal;
A portable terminal device comprising: signal conversion / amplification means for converting and amplifying an output signal of the inverse fast Fourier transform means into a signal capable of outputting an audible sound from the speaker and supplying the signal to the speaker.   7. The portable terminal device according to claim 6, wherein the modulation unit generates a third harmonic component as the odd harmonic component. A plurality of the modulation means are provided corresponding to the odd harmonic components of a plurality of different orders specified in advance,
7. The portable terminal device according to claim 6, wherein the intensity changing / adding means adds the output signal of the fast Fourier transform means and the output signals of the plurality of modulation means according to a predetermined intensity ratio.   The portable terminal device according to claim 6 or 7, wherein the intensity changing / adding means adds the intensity ratio of the output signal of the fast Fourier transform means and the output signal of the modulation means as 1: 1. .   The intensity changing / adding means is a condition that the intensity ratio between the output signals of the fast Fourier transform means and the output signals of all the modulation means to be added is the same as the intensity of the original signal. The portable terminal device according to claim 6, 7 or 8, characterized in that it can be arbitrarily changed below.

Images