JP3302934B2 - Sounding body drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sounding body driving device for driving a sounding body by applying an AC voltage to the sounding body.

[0002]

2. Description of the Related Art A signal tone is used in various electronic devices, such as a mobile phone and a portable personal computer, to notify a user of an incoming call and a state of the electronic device. This signal sound is generally generated by applying an AC voltage to a small sounding body. FIG. 10 is a perspective view showing this type of sounding body, FIG. 11 is an exploded perspective view of the sounding body, and FIG. 12 is a sectional view of the sounding body. As shown in FIG. 11, the sounding body 202 includes a terminal plate 204, a lower case 206, and a core 20.
8, a winding coil 210, a magnet 212, a diaphragm 214, and an upper case 216. As shown in FIG. 12, the iron core 208 is housed inside the coil 210, and the coil 210 is housed inside the annular magnet 212 which forms a magnetic circuit together with the iron core 208.

In this state, the iron core 208, the coil 210,
The magnet 212 is housed in a cylindrical lower case 206 disposed on the terminal plate 204, and a disk-shaped diaphragm 214 is provided on the upper edge of the lower case 206 so that the iron core 208, the coil 210, and the magnet 212 218 spacing between upper edge
It is arranged in. The two leads of the coil 210 are respectively connected to the terminals 20 projecting downward from the terminal plate 204.
2A and 202B, respectively, and are entirely housed in a cylindrical upper case 216.

FIG. 13 is a configuration diagram showing a conventional driving device for driving such a sounding body 202. As shown in FIG. The sounding body drive circuit 222 constituting the drive device 220 is a kind of oscillation circuit, and outputs a rectangular wave voltage having a substantially constant cycle.
The driving device 220 is provided with a switching circuit 2 for switching the volume of the sound generated by the sounding body 202, and thus the sound pressure.
The switching circuit 224 includes a manual switch 226 and resistors 228 and 230. 14A is a waveform diagram illustrating an output signal of the oscillation circuit, FIG. 14B is a timing chart illustrating a period in which each terminal of the switch 226 is connected to the contact piece, and FIG. FIG. 4D is a waveform diagram illustrating an output signal, and FIG. 3D is a graph illustrating an output sound pressure of the sounding body 202. In the figure, (A)
The horizontal axis of each drawing of (D) to (D) represents time, and the scales are all the same.

The contact 232 of the switch 226 is connected to a terminal 234.
(The period t in FIG. 14B)
1, t5), the output signal of the sounding body drive circuit 222 (FIG. 14)
(A)) is directly supplied to the sounding body without passing through a resistor, the amplitude becomes + Vcc ((C) in FIG. 14), and the sound pressure becomes maximum ((D) in FIG. 14). On the other hand, when the contact piece 232 is switched to the terminal 236 (periods t2 and t4 in FIG. 14B), the output signal of the sounding body drive circuit 222 is supplied to the sounding body 202 through the resistor 228 and the amplitude is, for example, Since V11 is 2/3 of + Vcc, the sound pressure is at an intermediate level. Further, when the contact piece 232 is switched to the terminal 238, the output signal of the sounding body drive circuit 222 is supplied to the sounding body 202 through the larger resistor 230, and the amplitude becomes, for example, V12 of 1/3 of + Vcc. , The sound pressure is lowest. Therefore, the user of the electronic device can set the volume of the signal sound to a desired level by switching the switch 226 as necessary.

[0006]

However, in such a conventional sounding body driving device, if the number of sound pressure switching steps is increased in order to improve convenience, for example, the number of resistors is increased according to the number of steps. It is necessary to increase the number of parts, and the number of components increases, which causes problems such as an increase in cost and an increase in mounting area. Further, since the hardware needs to be changed, the number of switching stages cannot be easily changed.

Further, when the switch 226 is switched, the DC level of the signal supplied to the sounding body 202 changes, so that the diaphragm 214 vibrates in a state where the center position of the vibration amplitude is deviated, thereby distorting the sound. This can be a problem, depending on the application. Further, since the switch 226 is manually switched, it cannot be switched at a high speed, and it is impossible to generate a signal sound whose sound pressure changes periodically, for example. It is possible to switch the resistance by replacing the switch 226 with an analog switch, but if it is simply replaced, the ON resistance of the analog switch becomes a problem, and the efficiency is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide a sound generator driving device capable of easily changing the number of sound pressure switching steps without increasing cost and mounting area. To provide. Another object of the present invention is to provide a sounding body driving device that prevents distortion of generated sound. Still another object of the present invention is to provide a sounding body driving device capable of switching sound pressure at high speed.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is a sounding body driving apparatus for driving an sounding body by applying an AC voltage to the sounding body, wherein the sounding body is provided with a DC voltage. When the AC voltage is applied in a superimposed manner, the loudness of the sound changes according to the magnitude of the DC voltage, and the driving device includes an oscillation circuit and a DC voltage added to an output signal of the oscillation circuit. A sound pressure control circuit for supplying to a sounding body, wherein the sound pressure control circuit generates a DC voltage whose magnitude changes according to a given control signal, and the voltage generation circuit generates the DC voltage. An adding circuit for adding a DC voltage and an output signal of the oscillation circuit and supplying the added signal to the sounding body.

In the sounding body driving device according to the present invention, the voltage generating circuit generates a DC voltage whose magnitude changes according to the applied control signal, and the adding circuit includes the DC voltage generated by the voltage generating circuit and the oscillation circuit. The output signal is added and supplied to the sounding body. Therefore, by controlling the DC voltage generated by the voltage generation circuit according to the control signal, it is possible to switch the volume of the sound emitted by the sounding body.

According to the present invention, the number of sound pressure switching stages can be increased very easily by changing the control signal. Further, since the control signal is merely changed, the cost and the mounting area do not increase as in the related art.

Further, the sound pressure can be switched at high speed by a control signal, and the sound pressure is switched while the sounding body is continuously sounding to generate a signal sound in which the sound pressure is periodically switched. Becomes possible.

Further, the present invention is a sounding body driving device for driving the sounding body by applying an AC voltage to the sounding body, wherein the sounding body includes a permanent magnet, first and second terminals, and both ends. A coil connected to the first and second terminals, and an iron core, wherein the permanent magnet, the coil, and the iron core form the same magnetic circuit, and a magnetic field generated by the magnetic circuit is applied to the vibrating portion. The driving device generates a sound, and the driving device includes an oscillation circuit that outputs a rectangular wave output signal having a low level voltage and a high level voltage, and a sound pressure control circuit to which an output signal of the oscillation circuit is supplied. Wherein the sound pressure control circuit comprises: first and second analog switches;
It has first and second input terminals, and when a low-level voltage is input to the first input terminal, the first terminal of the sounding body is grounded, and the second terminal is a positive voltage source. Respectively, and when a high-level voltage is input to the first input terminal, both the first terminal and the second terminal of the sounding body are disconnected from both the ground and a positive voltage source, When a high-level voltage is input to the second input terminal, the first terminal of the sounding body is connected to the positive voltage source, the second terminal is connected to the ground, and the second input terminal is connected to the second input terminal. A switching circuit that disconnects both the first terminal and the second terminal of the sounding body from both the ground and a positive voltage source when a low-level voltage is input, wherein the first analog switch includes the oscillation circuit. Circuit output terminal A second analog switch connected between the first input terminal of the switching circuit and turned on / off by a first control signal; a second analog switch connected to an output terminal of the oscillation circuit and the second input terminal of the switching circuit; When the first analog switch is turned on by the first and second control signals and the second analog switch is turned off, the coil is turned on and off. And the magnetic field generated by the permanent magnet is in the same direction, the first analog switch is turned off by the first and second control signals, and the second analog switch is turned on, It is characterized in that the direction of the magnetic field generated by the coil is opposite to the direction of the magnetic field generated by the permanent magnet.

In the sounding body driving device of the present invention, the polarity of the voltage applied to the sounding body can be switched between when the first analog switch is turned on and when the second analog switch is turned on. . The switching of the voltage polarity switches the direction of the magnetic field generated by the coil. If the magnetic field generated by the coil before the switching is, for example, the direction of increasing the magnetic field by the permanent magnet, the coil is generated after the switching. The magnetic field is in a direction to cancel and weaken the magnetic field by the permanent magnet. Therefore,
In this case, the DC component of the magnetic field generated by the magnetic circuit before switching is large, while the DC component of the magnetic field generated by the magnetic circuit after switching is small. Therefore, the sound emitted by the sounding body is large before the switching, and conversely, the sound emitted by the sounding body is small after the switching. That is, the sound pressure of the sounding body can be switched depending on which of the first and second analog switches is turned on. And
The sound pressure can be switched at high speed by switching the analog switch, and it is possible to switch the sound pressure while the sounding body is continuously sounding and generate a signal sound that changes periodically. Become.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing an example of a sounding body driving device according to the present invention, and FIG. 2 is a schematic block diagram. The sounding body driving device according to the present embodiment is generated depending on the magnitude of the DC voltage when an AC voltage is applied to the sounding body 202 shown in FIGS. 10 to 12 while being superimposed on a DC voltage (bias). It utilizes the property of the sounding body 202 that the sound volume changes. That is, as shown in FIG. 11 and the like, since the sounding body 202 is configured using a magnetic circuit including the magnet 212, even if the amplitude of the AC voltage is constant, the sounding body 202 is sounded according to the magnitude and polarity of the DC voltage. The sound pressure of the sound generated by the body 202 changes. FIG. 3 is a graph showing such a change in the output sound pressure of the sounding body 202. In the figure, the vertical axis represents the output sound pressure, and the horizontal axis represents the bias. As shown in FIG. 3, the sound pressure changes almost in proportion to the bias.
When it is increased to 2, Ib3, the sound pressure changes to small, medium, and large.

As shown in FIGS. 1 and 2, the sounding body driving device 2 according to the present embodiment emits sound by adding a bias voltage (DC voltage) to an oscillation circuit 4 and an output signal of the oscillation circuit 4. A sound pressure control circuit 6 for supplying a voltage to the body 202; the sound pressure control circuit 6 generates a DC voltage whose magnitude changes according to a given control signal 8; And an addition circuit 12 for adding the bias voltage thus obtained and the output signal of the oscillation circuit 4 and supplying the added signal to the sounding body 202.

The oscillation circuit 4 generates a rectangular wave having a substantially constant cycle, and includes an operational amplifier having a feedback circuit from an output terminal to an input terminal. More specifically, as shown in FIG. 1, the oscillation circuit 4 includes an operational amplifier 14, resistors 16, 18, and 20, and a capacitor 22. The resistor 16 is connected between the output terminal of the operational amplifier and the inverting input terminal 24, and the capacitor 22 is connected between the inverting input terminal 24 and the ground. The resistor 18 is connected between the output terminal of the operational amplifier and the non-inverting input terminal 26,
0 is connected between the non-inverting input terminal 26 and the ground. The operational amplifier 14 is supplied with a positive voltage Vcc and a negative voltage -Vcc as power supplies.

On the other hand, the adder circuit 12 is constituted by a voltage adder circuit using an operational amplifier, and more specifically, comprises an operational amplifier 28 and resistors 30 and 32 as shown in FIG.
The resistor 30 is connected between the output terminal of the operational amplifier 28 and the inverting input terminal 2.
The resistor 32 is connected between the inverting input terminal 24 of the operational amplifier 28 and the output terminal of the operational amplifier 14. The operational amplifier 28 has a positive voltage V
cc and a negative voltage -Vcc.

In this embodiment, the voltage generating circuit 10 comprises a D / A converter, and the output terminal 34 is connected to the non-inverting input terminal 26 of the operational amplifier 28.
In the present embodiment, a control signal 8 of a digital signal is supplied from a microcomputer (not shown) to the control terminal 36 of the voltage generation circuit 10. The terminal 202A of the sounding body 202 is connected to the output terminal of the operational amplifier 28 and the terminal 20A.
2B is connected to the ground.

Next, the operation of the sounding body driving device 2 configured as described above will be described. 4A to 4C are waveform diagrams showing signal waveforms of various parts of the sounding body driving device 2, and FIG. 4D is a graph showing the output sound pressure of the sounding body 202. The horizontal axis of each of the drawings (A) to (D) represents time,
The scales are all the same. FIG. 5 is an explanatory diagram showing switching of the sound volume.

In the oscillation circuit 4, the capacitor 22 is repeatedly charged and discharged. As a result, the output terminal of the operational amplifier 14 outputs a rectangular wave AC voltage as shown in FIG. Supplied. On the other hand, the control signal 36 of the digital signal is supplied to the control terminal 36 of the voltage generating circuit 10 as described above in order to set the sound pressure.
Steps S1 and S2), the voltage generation circuit 10 generates a bias voltage having a magnitude corresponding to the magnitude of the value represented by the digital signal (steps S3, S4 and S5 in FIG. 5), and the non-inversion of the operational amplifier 28 It is supplied to the input terminal 26. In addition,
In the present embodiment, the digital value of the control signal 8 is, as an example, as shown in FIG.
It is assumed that switching is made to three stages of Ib1.

The addition circuit 12 adds the bias voltage from the voltage generation circuit 10 to the AC voltage from the oscillation circuit 4, and as a result, the output voltage waveform of the operational amplifier 28 becomes as shown in FIG.
(C). That is, the value of the control signal 8 is the largest before the timing T1 and after the timing T4. At this time, the voltage V1 which is about half of the power supply voltage Vcc is added as a bias voltage to the AC signal having the rectangular waveform at the output of the operational amplifier 28. State. As a result, during these periods, the vibration of the sounding body 202 oscillates at the maximum amplitude (step S6 in FIG. 5), and the sound pressure of the sound generated by the sounding body 202 is as shown in FIG. (Step S7 in FIG. 5).

On the other hand, the value of the control signal 8 is an intermediate value in each of the periods from the timing T1 to T2 and from the timing T3 to T4. At this time, in the output of the operational amplifier 28, almost the ground level voltage is used as the bias voltage. ,
A state is added to the rectangular waveform AC signal. as a result,
During these periods, the vibration of the sounding body 202 oscillates at an intermediate amplitude (step S8 in FIG. 5), and the sound pressure of the sound generated by the sounding body 202 is, as shown in FIG. (Step S9 in FIG. 5).

During the period from the timing T2 to the timing T3, the value of the control signal 8 is the smallest. At this time, the output of the operational amplifier 28 has a voltage V2 which is about half of the power supply voltage -Vcc as a bias voltage and a rectangular waveform AC. It is in the state of being added to the signal. As a result, during these periods, the vibration of the sounding body 202 oscillates with the minimum amplitude (step S10 in FIG. 5), and the sound pressure of the sound generated by the sounding body 202 is reduced to the level shown in FIG.
(D), it becomes the smallest (step S11 in FIG. 5).

In this embodiment, when the number of sound pressure switching stages is further increased from three, the digital value of the control signal 8 supplied to the voltage generation circuit 10 may be further increased from three. Only by changing the control signal 8, the number of sound pressure switching stages can be changed very easily. Further, since the control signal 8 is merely changed, the cost and the mounting area are not increased unlike the related art. Further, the sound pressure can be switched at a high speed by switching the control signal 8, so that the sound pressure is switched while the sounding body 202 is continuously sounding to generate a signal sound in which the sound pressure is periodically switched. It becomes possible to do.

Next, a second embodiment of the present invention will be described. FIG. 6 is a circuit diagram showing a sounding body driving device according to the second embodiment. In the figure, the same elements as those in FIG. 1 are denoted by the same reference numerals, and a description thereof will be omitted here. The sounding body driving device 40 shown in FIG. 6 differs from the sounding body driving device 2 in that the connection of one of the power supply terminals of the operational amplifiers 14 and 28 is changed from -Vcc to ground. As a result, the output voltages of the operational amplifiers 14 and 28 change between the ground and + Vcc, and the signal waveforms of the respective parts are as shown in FIGS. 7A to 7C. That is, the AC signal generated by the oscillation circuit 4 is a rectangular wave that changes between the ground and + Vcc, as shown in FIG. The amount of change when the value of the control signal 8 is switched is smaller than that in the case of the sounding body driving device 2, and FIG.
(B), Ib3 ′, Ib2 ′, Ib
It is assumed that switching is made to three stages of 1 '.

As shown in FIG. 7C, the output signal of the adding circuit 12 changes around the voltages V1, V3, and V4 between the ground and + Vcc in response to the switching of the control signal 8. Is a rectangular wave. That is, the polarity is always positive and constant.

When the DC level of the output signal of the adder circuit 12 changes in this way, the output sound pressure of the sounding body 202 switches between large, medium, and low as shown in FIG. 7D. .

Also in the second embodiment, the number of digital pressure switching stages can be increased by increasing the number of digital values of the control signal 8 supplied to the voltage generating circuit 10, and the control signal 8 is changed. It is very easy to change the number of sound pressure switching stages. Further, since the control signal 8 is merely changed, the cost and the mounting area are not increased unlike the related art.

The sound pressure can be switched at a high speed by switching the control signal 8. Therefore, the signal in which the sound pressure is switched while the sounding body 202 is continuously sounding and the sound pressure is periodically switched is provided. It is possible to generate sound.

Next, a third embodiment of the present invention will be described.

FIG. 8 is a circuit diagram showing a sounding body driving device according to the third embodiment. In the figure, the same elements as those in FIG. 6 are denoted by the same reference numerals, and a description thereof will be omitted here.

As shown in FIG. 8, the sounding body driving device 70
Comprises an oscillation circuit 4 and a sound pressure control circuit 72 to which an output signal of the oscillation circuit 4 is supplied.

The sound pressure control circuit 72 includes first and second analog switches 74 and 76, and a switching circuit 78. The switching circuit 78 is connected to the first and second input terminals 8
0, 82, when a low-level voltage is input to the first input terminal 80, the terminal 202A of the sounding body 202 is connected to the ground, the terminal 202B is connected to the positive voltage source + Vcc, and the second When a high-level voltage is input to the input terminal 82, the terminal 202A of the sounding body 202 is connected to the positive voltage source + Vcc, and the terminal 202B is connected to the ground.

The first analog switch 74 is connected between the output terminal of the oscillation circuit 4 and the first input terminal 80 of the switching circuit 78, and is turned on / off by a control signal 84. Reference numeral 76 is connected between the output terminal of the oscillation circuit 4 and the second input terminal 82 of the switching circuit 78, and is turned on / off by a control signal 84.

The switching circuit 78 will be described in more detail. The switching circuit 78 includes first and second transistors 86 and 88, a first inverting circuit 90, and a first resistor 92. The base is connected to a first input terminal 80 and a first inverting circuit 90
Is connected to the first input terminal 80, the output terminal is connected to the base of the second transistor 88, and the first resistor 92 is connected between the power supply + Vcc and the base of the first transistor 86, The collector of the second transistor 88 is connected to the terminal 202A of the sounding body 202, the emitter is connected to the ground, the emitter of the first transistor 86 is connected to the power supply + Vcc, and the collector is connected to the terminal 202B of the sounding body 202, respectively. .

Further, the switching circuit 78 includes third and fourth transistors 94 and 96, a second inverting circuit 98,
And a second resistor 100, the base of the third transistor 94 is connected to the second input terminal 82, the input terminal of the second inversion circuit 98 is connected to the base of the third transistor 94, and the output terminal is connected to the second input terminal 82. 4 are connected to the bases of the transistors 96, respectively.
The collector of the fourth transistor 96 is connected to the terminal 20 of the sounding body 202.
2A, the emitters are connected to the power supply + Vcc, respectively.
The emitter of the third transistor 94 is connected to the ground, and the collector is connected to the terminal 202B of the sounding body 202.

Next, the operation of the sounding body driving device 70 thus configured will be described. 9 (A) to 9 (C) are waveform diagrams showing signal waveforms at various parts of the sounding body drive device 70, and FIG. 9 (D) is a graph showing the output sound pressure of the sounding body 202. In the drawings, the horizontal axis of each of the drawings (A) to (D) represents time, and the scales are all the same. Here, FIG.
As shown in (B), the high-level control signal 84 is supplied to the first analog switch 74 in the periods t1 and t3 to turn on the first analog switch 74, while the high-level control signal 84 is supplied to the second analog switch 74 in the period t2. It is supplied to the switch 76 to be turned on.

First, in the periods t1 and t3, the first analog switch (AS) 74 is turned on as described above.
When the output signal of the oscillation circuit 4 ((A) in FIG. 9) is at the ground level, a base current flows through the first transistor 86 and the first transistor 86 turns on. Since a high-level voltage is applied through the first inverting circuit 90, the second transistor 88 is also turned on. Therefore, the terminal 20 of the sounding body 202
2A is connected to the ground, and a voltage + V is applied to the terminal 202B.
cc is applied. However, when the output signal of the oscillation circuit 4 ((A) in FIG. 9) is at a high level, none of the transistors is turned on, so that no voltage is applied to the sounding body 202. Therefore, as shown in FIG. 9C, the voltage + Vcc is applied to the sounding body 202 at the period of the AC signal output from the oscillation circuit 4. At this time, the winding coil 21
The magnetic field generated by 0 is in the same direction as the magnetic field generated by the magnet 212, and since these magnetic fields are added, the DC component of the magnetic field generated by the magnetic circuit including the winding coil 210 and the magnet 212 increases. The output sound pressure of the sounding body 202 is at a high level as shown in FIG.

On the other hand, in the period t2, since the second analog switch 76 is turned on, the output signal of the oscillation circuit 4 (FIG. 9)
(A)) is at a high level, the third transistor 9
4, a base current flows, and the third transistor 94 is turned on. On the other hand, a ground level voltage is applied to the base of the fourth transistor 96 through the second inverting circuit 98, so that the fourth transistor 96 is also turned on. I do. Therefore, the terminal 202B of the sounding body 202 is connected to the ground, and the voltage + Vcc is applied to the terminal 202A. However, when the output signal of the oscillation circuit 4 ((A) in FIG. 9) is at a low level, no transistor is turned on, so that no voltage is applied to the sounding body 202. Therefore, as shown in FIG. 9C, the voltage + Vcc is applied to the sounding body 202 at the cycle of the AC signal output from the oscillation circuit 4, but in this case, the polarity is reversed and the terminal + Vcc is applied. This is equivalent to the case where the voltage -Vcc is applied to 202A. At this time,
The magnetic field generated by the winding coil 210 is in the opposite direction to the magnetic field generated by the magnet 212, and the magnetic field generated by the magnet 212 is canceled by the magnetic field generated by the winding coil 212, and the DC component of the magnetic field generated by the magnetic circuit is reduced. Therefore, sounding body 2
The output sound pressure of No. 02 has a small level as shown in FIG.

Also in the case of the third embodiment, the sound pressure can be switched at high speed by switching the control signal.
Therefore, it is possible to switch the sound pressure while the sounding body 202 is continuously sounding to generate a signal sound in which the sound pressure is periodically switched.

[0042]

As described above, the present invention is a sounding body driving device for driving the sounding body by applying an AC voltage to the sounding body. When a voltage is applied, the loudness of the sound changes according to the magnitude of the DC voltage, and the driving device includes an oscillating circuit, and a sound supplied to the sounding body by adding the DC voltage to an output signal of the oscillating circuit. A pressure control circuit, wherein the sound pressure control circuit comprises: a voltage generation circuit that generates a DC voltage whose magnitude changes according to a given control signal; and the DC voltage generated by the voltage generation circuit and the oscillation circuit. And an addition circuit for adding the output signal to the sound generator.

In the sounding body driving device according to the present invention, the voltage generating circuit generates a DC voltage whose magnitude changes according to the applied control signal, and the adding circuit includes the DC voltage generated by the voltage generating circuit and the oscillating circuit. The output signal is added and supplied to the sounding body. Therefore, by controlling the DC voltage generated by the voltage generation circuit according to the control signal, it is possible to switch the volume of the sound emitted by the sounding body.

In the present invention, the number of sound pressure switching stages can be increased very easily by changing the control signal. Further, since the control signal is merely changed, the cost and the mounting area do not increase as in the related art.

Further, the sound pressure can be switched at a high speed by the control signal, and the sound pressure is switched while the sounding body is continuously sounding to generate a signal sound in which the sound pressure is periodically switched. Becomes possible.

A sounding body driving device for driving the sounding body by applying an AC voltage to the sounding body, wherein the sounding body includes a permanent magnet, first and second terminals, and both ends of the first and second sounds. The permanent magnet, the coil, and the iron core form the same magnetic circuit, and the magnetic field generated by the magnetic circuit acts on the vibrating part to generate sound. The driving device includes an oscillation circuit that outputs a rectangular wave output signal having a low level voltage and a high level voltage, and a sound pressure control circuit to which an output signal of the oscillation circuit is supplied. The pressure control circuit has first and second analog switches and first and second input terminals, and when a low-level voltage is input to the first input terminal, the first of the sounding body Terminal to ground, the second terminal When a high-level voltage is input to the first input terminal, both the first terminal and the second terminal of the sounding body are connected to both the ground and the positive voltage source. Disconnecting, when a high-level voltage is input to the second input terminal, the first terminal of the sounding body is connected to the positive voltage source, and the second terminal is connected to the ground; A switching circuit for disconnecting both the first terminal and the second terminal of the sounding body from both ground and a positive voltage source when a low-level voltage is input to the input terminal of the first analog circuit. A switch connected between an output terminal of the oscillation circuit and the first input terminal of the switching circuit;
A second analog switch is connected between an output terminal of the oscillation circuit and the second input terminal of the switching circuit, and is turned on / off by a second control signal; The first and second control signals cause a first
When the analog switch is turned on and the second analog switch is turned off, the direction of the magnetic field generated by the coil and the direction of the magnetic field generated by the permanent magnet become the same, and the first and second control signals When the first analog switch is turned off and the second analog switch is turned on, the direction of the magnetic field generated by the coil is opposite to the direction of the magnetic field generated by the permanent magnet. It is characterized by.

In the sounding body drive device of the present invention, the polarity of the voltage applied to the sounding body can be switched between when the first analog switch is turned on and when the second analog switch is turned on. . The switching of the voltage polarity switches the direction of the magnetic field generated by the coil. If the magnetic field generated by the coil before the switching is, for example, the direction of increasing the magnetic field by the permanent magnet, the coil is generated after the switching. The magnetic field is in a direction to cancel and weaken the magnetic field by the permanent magnet. Therefore,
In this case, the DC component of the magnetic field generated by the magnetic circuit before switching is large, while the DC component of the magnetic field generated by the magnetic circuit after switching is small. Therefore, the sound emitted by the sounding body is large before the switching, and conversely, the sound emitted by the sounding body is small after the switching. That is, the sound pressure of the sounding body can be switched depending on which of the first and second analog switches is turned on. And
The sound pressure can be switched at high speed by switching the analog switch, and it is possible to switch the sound pressure while the sounding body is continuously sounding and generate a signal sound that changes periodically. Become.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an example of a sounding body driving device according to the present invention.

FIG. 2 is a schematic block diagram showing an example of a sounding body driving device according to the present invention.

FIG. 3 is a graph showing a change in output sound pressure of a sounding body.

4 (A) to 4 (C) are waveform diagrams showing signal waveforms of various parts of the sounding body drive device of FIG. 1, and FIG. 4 (D) is a graph showing an output sound pressure of the sounding body.

FIG. 5 is an explanatory diagram showing switching of sound volume.

FIG. 6 is a circuit diagram showing a sounding body driving device according to a second embodiment.

FIGS. 7A to 7C are waveform diagrams showing signal waveforms of respective units in the second embodiment, and FIG. 7D is a graph showing an output sound pressure of a sounding body.

FIG. 8 is a circuit diagram showing a sounding body driving device according to a third embodiment.

9 (A) to 9 (C) are waveform diagrams showing signal waveforms of various parts of the sounding body driving device, and FIG. 9 (D) is a graph showing the output sound pressure of the sounding body.

FIG. 10 is a perspective view showing a sounding body.

FIG. 11 is an exploded perspective view of the sounding body.

FIG. 12 is a sectional view of a sounding body.

FIG. 13 is a configuration diagram showing a conventional driving device for driving a sounding body.

14A is a waveform chart showing an output signal of an oscillation circuit, FIG.
(B) is a timing chart showing a period in which each terminal of the switch of the sounding body drive circuit of FIG. 13 is connected to the contact piece;
(C) is a waveform diagram showing an output signal of the sounding body drive circuit,
(D) is a graph showing the output sound pressure of the sounding body.

[Explanation of symbols]

2 ... Sound generator driving device, 4 ... Oscillation circuit, 6 ... Sound pressure control circuit, 8 ... Control signal, 10 ... Voltage generation circuit, 12
...... Addition circuit, 14 ... Op amp, 16 ... Resistance, 1
8 ... resistor, 20 ... resistor, 22 ... capacitor, 24
... Inverting input terminal, 26... Non-inverting input terminal, 28.
Operational amplifier, 30: resistor, 32: resistor, 34: output terminal, 36: control terminal, 40: sounding body driving device,
70: sounding body driving device, 72: sound pressure control circuit, 74
... First analog switch, 76 second analog switch, 78 switching circuit, 80 first input terminal, 82 second input terminal, 84 control signal, 8
6 first transistor, 88 second transistor, 90 first inverting circuit, 92 first resistor, 9
4, a third transistor, 96, a fourth transistor, 98, a second inverting circuit, 100, a second resistor,
202 ... sounding body, 204 ... terminal board, 206 ... lower case, 208 ... iron core, 210 ... winding coil, 212
... magnet, 214 ... diaphragm, 216 ... upper case.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G10K 9/13 102 G10K 9/12

Claims (11)

(57) [Claims] 1. A sounding body driving apparatus for driving an sounding body by applying an AC voltage to a sounding body, wherein the sounding body is superimposed on a DC voltage and the DC voltage is applied when the AC voltage is applied. The driving device comprises: an oscillation circuit; and a sound pressure control circuit that adds a DC voltage to an output signal of the oscillation circuit and supplies the signal to the sounding body. A voltage control circuit configured to generate a DC voltage having a magnitude that varies according to a given control signal; adding the DC voltage generated by the voltage generation circuit to an output signal of the oscillation circuit to generate the sound; A sounding body driving device, comprising: an adding circuit for supplying to a body. 2. The sounding body driving device according to claim 1, wherein said oscillation circuit generates a rectangular wave signal having a substantially constant cycle. 3. The sounding body driving device according to claim 2, wherein the oscillation circuit includes an operational amplifier having a feedback circuit formed from an output terminal to an input terminal. 4. The apparatus according to claim 1, wherein said adding circuit is constituted by a voltage adding circuit using an operational amplifier.
The sounding body driving device as described in the above. 5. The sounding body driving device according to claim 1, wherein the control signal is a digital signal, and the voltage generation circuit converts the digital signal into an analog voltage and outputs the analog signal as the DC voltage. 6. The sounding body includes a coil, an iron core housed inside the coil, and a diaphragm made of a ferromagnetic material arranged close to the iron core, and an output voltage of the adding circuit is 2. The voltage applied to the coil.
The sounding body driving device as described in the above. 7. The sounding body driving device according to claim 6, wherein the sounding body further includes an annular magnet that accommodates the coil inside and forms a magnetic circuit together with the iron core. 8. The sounding body driving device according to claim 1, wherein the polarity of the output voltage of the adding circuit is constant. 9. The sounding body driving device according to claim 1, wherein the polarity of the output voltage of the adding circuit changes. 10. A sounding body driving device for driving an sounding body by applying an AC voltage to a sounding body, wherein the sounding body includes a permanent magnet, first and second terminals, and both ends of the first and second terminals. The permanent magnet, the coil, and the iron core include a coil connected to the second terminal, and an iron core. The permanent magnet, the coil, and the iron core form the same magnetic circuit. Wherein the driving device has a rectangular waveform having a low level voltage and a high level voltage.
An oscillation circuit for outputting an output signal of the oscillation circuit; and a sound pressure control circuit to which an output signal of the oscillation circuit is supplied, wherein the sound pressure control circuit comprises: a first and a second analog switch; When a low-level voltage is input to the first input terminal, the first terminal of the sounding body is connected to ground, and the second terminal is connected to a positive voltage source. A high level voltage is applied to the first input terminal.
A first terminal and a second end of the sounding body when input;
Disconnect both ground and positive voltage sources
And when a high-level voltage is input to the second input terminal, the first terminal of the sounding body is connected to the positive voltage source, and the second terminal is connected to ground,
Before the low-level voltage is input to the second input terminal
Connect both the first and second terminals of the phonetic
A first analog switch connected between an output terminal of the oscillating circuit and the first input terminal of the switching circuit . on and off by the control signal, the second analog switch is turned on and off by the connected second control signal between the second input terminal of the switching circuit and the output terminal of the oscillation circuit, wherein The first analog switch is controlled by the first and second control signals.
Switch turns on and the second analog switch turns off
And the direction of the magnetic field generated by the coil and the direction of the permanent magnet
The direction of the generated magnetic field is the same as that of the first analog switch.
Switch turns off and the second analog switch turns on
And the direction of the magnetic field generated by the coil and the direction of the permanent magnet
The generated magnetic field is configured to be in the opposite direction.
That, sounding body driving device, characterized in that. 11. The switching circuit according to claim 1, wherein the switching circuit comprises first and second switches.
, A first inverting circuit, and a first resistor, a base of the first transistor is connected to the first input terminal, and an input terminal of the first inverting circuit is connected to the first input terminal.
The output terminal is connected to the base of the second transistor, and the first resistor is connected between a positive voltage source and the first input terminal, and the output terminal of the second transistor A collector is connected to the first terminal of the sounding body, an emitter is connected to ground, an emitter of the first transistor is connected to the positive voltage source, and a collector is connected to the second terminal of the sounding body. The switching circuit further includes third and fourth transistors, a second inverting circuit, and a second resistor; a base of the third transistor is connected to the second input terminal; The input terminal of the inverting circuit of the second
The output terminal is connected to the base of the fourth transistor, the second resistor is connected between the ground and the second input terminal, and the collector of the fourth transistor is To the first terminal of the sounding body,
The emitter of the third transistor is connected to the ground, the emitter of the third transistor is connected to the ground, and the collector is connected to the second terminal of the sounding body. Sounding body drive.