JP2000347678A - Tone generating circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tone generating circuit capable of obtaining sufficient sound pressure level by the use of a magnetic sounder by respectively comparing voice signals output from two sound sources with a threshold value to binarily output, and adding together the two signals. SOLUTION: When a tone generating circuit 100 adds together two tones, the tones Vtn1, Vtn2 output from two sound sources 1, 2 are respectively approximately converted into binary by binary approximate circuits 3, 4, and the binary approximate output Vcmp1, Vcmp2 are added together by an adder 5 to obtain output waveform Vout of ternary approximate rectangular wave. The output waveform Vout becomes approximate waveform of waveform (sin waveform) directly adding together the tones Vtn1, Vtn2, it contains the many same frequency components as the two tones. Further, because rising-up/fall down of the wave form are steep, it is suitable to obtain sound pressure by a magnetic sounder or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tone generation circuit using a magnetic sounder.

[0002]

2. Description of the Related Art Conventionally, a small magnetic sounder is often used to generate a ring tone or the like of a portable telephone device, and there is an increasing market demand that two or more tones be produced simultaneously using the magnetic sounder. I have. FIG. 7 is an electric circuit diagram showing a configuration of a conventional tone generation circuit 100B.
As shown in FIG. 7, a conventional tone generation circuit 100B includes:
When adding two tones, the tones Vtn1s and Vtn, which are sine waves output from the two sound sources 31 and 32,
2s is added by the adder 35 to obtain an output waveform Vo.
ut.

[0003]

However, there is a problem that a sufficient sound pressure level cannot be obtained when a magnetic sounder is used in a conventional added waveform of sine waves. The present invention has been made in view of such a problem, and an object of the present invention is to provide a tone generation circuit that can obtain a sufficient sound pressure level when using a magnetic sounder. is there.

[0004]

Means for Solving the Problems In order to solve the above problems, the present invention has the following constitution. The gist of the invention according to claim 1 is a tone generation circuit including a plurality of sound sources, wherein a sound source A that generates a sound signal A and the sound signal A output from the sound source A are compared with a threshold value. 2
Binary approximation means A for converting and outputting a value, a sound source B for generating a sound signal B, and a binary approximation means for converting the sound signal B output from the sound source B to a threshold value for binarization and outputting B, and an adder for adding the audio signal A and the audio signal B. The gist of the invention according to claim 2 is that the binary approximation means A compares the voltage level of the audio signal A with a level of a reference voltage input from the outside as a threshold, and determines that the voltage level of the audio signal A is 2. The voltage comparator according to claim 1, wherein the voltage comparator outputs an H level when the voltage level is higher than the reference voltage level, and outputs an L level when the voltage level of the audio signal A is lower than the reference voltage level. It resides in the tone generation circuit. The gist of the invention according to claim 3 is that the binary approximation means B compares the voltage level of the audio signal B with a level of the reference voltage input from the outside as a threshold, and determines a voltage level of the audio signal B. 2. A voltage comparator which outputs an H level when is higher than the level of the reference voltage, and outputs an L level when the voltage level of the audio signal B is lower than the level of the reference voltage. 2. The tone generation circuit according to item 2. The gist of the invention according to claim 4 is that the adding means inputs the outputs of the binary approximation means A and the binary approximation means B to a non-inverting input terminal, and inputs the reference voltage to an inverting input terminal, 4. The tone generating circuit according to claim 1, further comprising an operational amplifier having an output connected to the non-inverting input terminal via a feedback resistor. The gist of the invention according to claim 5 is that the non-inverting input terminal of the operational amplifier and the binary approximation means A
A tone generating circuit according to claim 4, wherein a resistor is interposed between the tone generating circuit and the tone generating circuit. The gist of the invention according to claim 6 is that a resistor is interposed between the non-inverting input terminal of the operational amplifier and the binary approximation means B. In the tone generation circuit. The gist of the invention according to claim 7 is that the audio signal A generated by the sound source A and the audio signal B generated by the sound source B are analog signals. Or the tone generation circuit according to any of the first to third aspects. The gist of the invention described in claim 8 is that the binary approximation means A is a code extraction circuit that extracts and outputs only two predetermined values of the audio signal A. 7. The tone generation circuit according to any one of claims 1 to 7, The gist of the present invention is that the binary approximation means B is a code extraction circuit for extracting and outputting only two predetermined values of the audio signal B. In the tone generating circuit according to any one of the first to eighth aspects. The gist of the invention according to claim 10 is that the adding means includes:
10. The tone generation circuit according to claim 8, wherein an output of the binary approximation unit A and an output of the binary approximation unit B are added and output as a ternary digital audio signal output. The gist of the invention according to claim 11 is that the tone generation circuit according to claim 10, further comprising a digital / analog converter for converting a ternary digital audio signal output from the adding means into an analog audio signal. Exists. The gist of the invention according to claim 12 is that the audio signal A generated by the sound source A and the audio signal B generated by the sound source B are digital signals. Or the tone generation circuit according to any of the first to third aspects. The gist of the invention described in claim 13 is as follows.
12. An IC provided with the tone generating circuit according to any one of the above items 12. The gist of the invention described in claim 14 is that
2. An electric circuit board comprising the tone generating circuit according to any one of 2. The gist of the invention according to claim 15 resides in a mobile communication device including the tone generation circuit according to any one of claims 1 to 12. The gist of the invention described in claim 16 is:
A portable telephone comprising the tone generating circuit according to any one of claims 1 to 12. The gist of the invention according to claim 17 is a tone generating method including a plurality of sound sources, wherein the sound source A generates the audio signal A, and the binary approximation means A outputs the sound source A.
The audio signal A output from is binarized and output by comparing the audio signal A with a threshold, and the sound source B generates an audio signal B;
Binary approximation means B binarizes and outputs the audio signal B output from the sound source B by comparing the audio signal B with a threshold, and adds the audio signal A and the audio signal B by adding means. The tone generation method is as follows.

[0005]

Embodiments of the present invention will be described below in detail with reference to the drawings. Embodiment 1 FIG. 1 is an electric circuit diagram showing a tone generation circuit 100 according to a first embodiment of the present invention. As shown in FIG.
When adding two tones, the tone generation circuit 100 according to the first embodiment converts the tones Vtn1 and Vtn2 output from the two sound sources 1 and 2 into binary approximation circuits 3 and 4.
Approximate conversion to binary values respectively, and the binary approximate output V
By adding cmp1 and Vcmp2 by the adder 5, an output waveform Vout, which is a ternary approximate rectangular wave, is obtained. The output waveform Vout includes the tones Vtn1 and Vtn2.
Is an approximate waveform of a waveform (sin waveform) obtained by directly adding, and contains many of the same frequency components as the two tones. Further, since the rise / fall of the waveform is steep, it is suitable for obtaining sound pressure by a magnetic sounder or the like.

FIG. 2 shows the tone generation circuit 10 shown in FIG.
FIG. 3 is an electric circuit diagram illustrating an internal configuration of a zero. In the first embodiment, only an analog circuit is used. The sound source 1 and the sound source 2 include an analog sound source 11 and an analog sound source 12, respectively. The binary approximation circuit 3 and the binary approximation circuit 4 include a comparator 13 and a comparator 14, respectively. The adder 5 includes an analog adder 15.

The analog tone generators 11 and 12 output two different tones Vtn1 and Vtn2. The tones Vtn1 and Vtn2 are input to comparators 13 and 14, respectively, are compared with a reference voltage VR, and a binary approximation output V
Approximately converted to cmp1 and Vcmp2. The binary approximation outputs Vcmp1 and Vcmp2 are output from the operational amplifier 18 and the resistor 16
Are added by an analog adder 15 having an inverting amplifier configuration, and a ternary output waveform Vout is obtained.

Next, the operation of the first embodiment will be described with reference to FIGS.

FIG. 3 shows the analog waveforms of the tones Vtn1 and Vtn2 output from the analog sound sources 11 and 12 of the tone generating circuit 100 according to the first embodiment of the present invention.
Tones Vtn1 and Vtn2 are output from comparators 13 and 14,
Are compared with the reference voltage VR, respectively, and the value of the reference voltage VR is set to the center value of each sound source output. Assuming that the high level voltage output from each of the comparators 13 and 14 is VH and the low level voltage is VL, the waveforms of the binary approximation outputs Vcmp1 and Vcmp2 are as shown in FIG. When these two outputs (Vcmp1 and Vcmp2) are added by the analog adder 15 with a gain of 0.5,
The waveform of the output waveform Vout after the addition is as shown by the solid line in FIG. When a waveform (conventional technology) obtained by directly adding the tones Vtn1 and Vtn2 is superimposed, a dotted line is obtained.

Comparing the two shown in FIG. 5, the added output waveform (Vout) according to the present invention is an approximate waveform of the added waveform according to the prior art.
It can be seen that the output tone Vtn1 and Vtn2 contain many frequency components. Further, since the change of the rising / falling of the waveform is steeper than in the related art, the waveform is suitable for driving a magnetic sounder or the like in which sound pressure cannot be obtained unless rectangular wave driving is performed.

[0011] Tone generation circuit 1 according to the first embodiment
Since 00 is configured as described above, the following effects are obtained. An effect of the present invention is that even when two or more tones are added, the sound can be sounded at a higher sound pressure than a conventional technique using a magnetic sounder or the like.

The reason for this is that a magnetic sounder or the like that can generate sound pressure by a rectangular wave is driven by a waveform converted into an approximate rectangular waveform having the same rise / fall as the rectangular wave.

Embodiment 2 Next, a second embodiment of the present invention will be described with reference to the drawings. In the second embodiment, a case where the present invention is realized by a digital circuit will be described.

FIG. 6 is an electric circuit diagram showing a tone generating circuit 100A according to a second embodiment of the present invention. The second embodiment differs from the first embodiment in that the sound sources are digital sound sources 21 and 22, the binary approximation circuits are the code extraction circuits 23 and 24, and the adder is a digital adder 25. However, D / A of ternary output is further provided at the output unit.
A converter 26 has been added. Digital sound source 21,
Reference numeral 22 outputs two's complement digital tone signals Dtn1 and Dtn2 having a predetermined number of bits. The digital tone signals Dtn1 and Dtn2 are signals from which respective tone waveforms can be obtained by D / A conversion.
The code extraction circuits 23 and 24 output the digital tone signal Dtn
1, code bits Dcmp1 and Dcmp of Dtn2
Only 2 (binary) is extracted and output. This operation is equivalent to the operations of the comparators 13 and 14 of the first embodiment. The obtained sign bits Dcmp1, Dcmp2
Is converted to a ternary digital signal by passing the digital signal to a digital adder 25 and converted into an analog voltage by a ternary output D / A converter 26. An equivalent waveform is obtained.

The second embodiment has an advantage that the area can be reduced when the central portion of the circuit is constituted by a digital circuit, for example, when constituted on a semiconductor integrated circuit.

In these embodiments, the present invention is not limited to the embodiments, and can be applied to a mode suitable for applying the present invention.

The number, position, shape, and the like of the above-mentioned constituent members are not limited to the above-described embodiment, but can be set to a number, position, shape, and the like suitable for carrying out the present invention.

In the drawings, the same components are denoted by the same reference numerals.

[0019]

Since the present invention is constructed as described above, it is possible to obtain a sufficient sound pressure level even when a magnetic sounder is used in a tone generating circuit. Play.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram illustrating a tone generation circuit 100 according to a first embodiment of the present invention.

FIG. 2 is an electric circuit diagram showing an internal configuration of the tone generation circuit 100 shown in FIG.

FIG. 3 is a diagram illustrating analog waveforms of tones Vtn1 and Vtn2 illustrated in FIG. 2;

FIG. 4 is a diagram showing binary approximate outputs Vcmp1 and Vcm shown in FIG. 2;
It is a figure showing the waveform of p2.

FIG. 5 is a diagram showing an output waveform Vout shown in FIG.

FIG. 6 is an electric circuit diagram illustrating a tone generation circuit 100A according to a second embodiment of the present invention.

FIG. 7 is an electric circuit diagram showing a configuration of a conventional tone generation circuit 100B.

[Explanation of symbols]

 1, 2 sound source 3, 4 binary approximation circuit 5 adder 11, 12 analog sound source 13, 14 comparator 15 analog adder 16 resistor 18 operational amplifier 21, 22 digital sound source 23, 24 code extraction circuit 25 digital adder 26 D / A Converters 31, 32 Sound source 35 Adder 35 100 Tone generator 100A Tone generator 100B Tone generator Dtn1 Digital tone signal Dtn2 Digital tone signal Dcmp1 Sign bit Dcmp2 Sign bit Vcmp1 Binary approximation output Vcmp2 Binary approximation output Vout Output tone Vtn1 Vtn2 tone Vtn1s tone Vtn2s tone VR Reference voltage

Claims (17)

[Claims] 1. A tone generating circuit having a plurality of sound sources, comprising: a sound source A for generating a sound signal A; and a binarization output by comparing the sound signal A output from the sound source A with a threshold value. A binary approximation unit A that generates an audio signal B; a binary approximation unit B that binarizes and outputs the audio signal B output from the audio source B by comparing the audio signal B with a threshold value; A tone generating circuit comprising an audio signal A and an adding means for adding the audio signal B. 2. The audio signal A
Is compared with the level of an externally input reference voltage as a threshold, and when the voltage level of the audio signal A is higher than the level of the reference voltage, an H level is output, and the voltage level of the audio signal A is 2. The tone generation circuit according to claim 1, wherein the voltage comparator outputs an L level when the level is lower than the level of the reference voltage. 3. The binary approximation means B outputs the audio signal B
Is compared with the level of the reference voltage input from the outside as a threshold value, and when the voltage level of the audio signal B is higher than the level of the reference voltage, an H level is output. 3. The tone generation circuit according to claim 1, wherein the tone generator is a voltage comparator that outputs an L level when is smaller than the level of the reference voltage. 4. The non-inverting input terminal receives the output of the binary approximation unit A and the output of the binary approximation unit B, inputs the reference voltage to an inversion input terminal, and outputs the non-inversion input terminal. 4. The tone generating circuit according to claim 1, further comprising an operational amplifier connected to the input terminal via a feedback resistor. 5. The tone generating circuit according to claim 4, wherein a resistor is interposed between said non-inverting input terminal of said operational amplifier and said binary approximation means A. 6. The tone generating circuit according to claim 4, wherein a resistor is interposed between said non-inverting input terminal of said operational amplifier and said binary approximation means B. 7. The sound signal A generated by the sound source A
7. The tone generation circuit according to claim 1, wherein the sound signal B generated by the sound source B is an analog signal. 8. The audio signal A
8. A tone generation circuit according to claim 1, wherein the code extraction circuit extracts and outputs only two predetermined values. 9. The audio signal B
9. The tone generation circuit according to claim 1, wherein the code extraction circuit extracts and outputs only two values determined among the above. 10. The binary approximation means A, wherein:
10. The tone generation circuit according to claim 8, wherein an output of the tone approximation means B and an output of the binary approximation means B are added and output as a ternary digital audio signal output. 11. A tone generating circuit according to claim 10, further comprising a digital / analog converter for converting a ternary digital audio signal output from said adding means into an analog audio signal. 12. The sound signal A generated by the sound source A
12. The tone generation circuit according to claim 8, wherein the sound signal B generated by the sound source B is a digital signal. 13. An IC comprising the tone generation circuit according to claim 1. 14. An electric circuit board comprising the tone generating circuit according to claim 1. 15. A mobile communication device comprising the tone generation circuit according to claim 1. 16. A portable telephone comprising the tone generating circuit according to claim 1. 17. A tone generating method comprising a plurality of sound sources, wherein a sound source A generates a sound signal A, and a binary approximation means A compares the sound signal A output from the sound source A with a threshold value. The sound source B generates an audio signal B, and the binary approximation means B binarizes and outputs the audio signal B output from the audio source B by comparing the audio signal B with a threshold. Means, said audio signal A and said audio signal B
And a tone generation method.