Sound pressure control device, sound pressure control system for sounder, and sound pressure control method for sounder

Abstract

To enable precise sound pressure control of a sounder without using an SG port, at a relatively low cost, by setting fine adjustment of a pulse signal's frequency and duty ratio.SOLUTION: A sound pressure control device 10 that controls sound pressure of a sounder 13 via pulse width modulation comprises: a microprocessor (CPU11) that generates a first sound pressure control signal comprising a first frequency and a first duty ratio, and a second sound pressure control signal comprising a second frequency higher than the first frequency and an arbitrary duty ratio, and outputs the respective signals via input / output ports corresponding to the first and second sound pressure control signals; and a synthesis circuit (12) that combines the first sound pressure control signal and the second sound pressure control signal to generate a third sound pressure control signal, and outputs the third sound pressure control signal to drive the sounder.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sound pressure control device that controls the sound pressure of a sounder by pulse width modulation. [Background technology]

[0002] A sound pressure control device for a piezoelectric buzzer consisting of a separately excited piezoelectric diaphragm normally uses a sound generator port (SG terminal) of a microprocessor to drive the piezoelectric buzzer by controlling the duty ratio with PWM (Pulse Width Modulation), thereby variably controlling the sound pressure of the piezoelectric buzzer. Note that a technology for variably controlling the sound pressure of a piezoelectric buzzer using PWM control is described in, for example, Patent Document 1.

[0003] Also, for example, Non-Patent Document 1 discloses the hardware manual for the microcomputer RL78 / D1A from Renesas Electronics Corporation. According to this document, Figure 18-1 on page 1081 shows a block diagram of the internal configuration of a sound generator, and describes a configuration in which a microcomputer equipped with an SG port has a built-in frequency generation circuit (Tone) and sound pressure control circuit (PWM), and uses the corresponding SG terminals (SGO, SGA) to output corresponding Tone signals and PWM signals, thereby controlling the sound pressure of a sounder such as a piezoelectric buzzer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4468982 (see paragraph

[0007] , Figure 1) [Non-Patent Document 1] RENESAS Microcontroller RL78 / D1A User's Manual: Hardware Rev.1.10 (March 23, 2015) Summary of the Invention [Problem to be solved by the invention]

[0005] However, microcontrollers equipped with an SG port are relatively expensive, and microcontrollers using an SG port can only obtain piezoelectric control signals with a fixed duty cycle at a fixed period. Therefore, there has been a demand for a microcontroller that can precisely set and control the frequency and duty ratio used as the sound pressure control signal.

[0006] Therefore, an object of the present invention is to provide a sound pressure control device or the like that is relatively inexpensive and does not use an SG port, and that can precisely set the frequency and duty ratio of a pulse signal, thereby enabling precise control of the sounder's sound pressure.

[0007] Other objects of the present invention will become apparent to those skilled in the art by referring to the following exemplary aspects and best modes, as well as the accompanying drawings. [Means for solving the problem]

[0008] In order to facilitate an understanding of the outline of the present invention, the following examples are given of embodiments according to the present invention.

[0009] A first aspect according to the present invention is a sound pressure control device that controls the sound pressure of a sounder by pulse width modulation, and includes a microprocessor that generates a first sound pressure control signal consisting of a first frequency and a first duty ratio, and a second sound pressure control signal consisting of a second frequency higher than the first frequency and an arbitrary duty ratio, and outputs the first sound pressure control signal and the second sound pressure control signal via input / output ports corresponding to each of them, and a synthesis circuit that synthesizes the first sound pressure control signal and the second sound pressure control signal to generate a third sound pressure control signal, and outputs the third sound pressure control signal to drive the sounder.

[0010] In a first aspect, a sound pressure control device that controls the sound pressure of a sounder by pulse width modulation is configured so that a microprocessor generates a first sound pressure control signal consisting of a first frequency and a first duty ratio, and a second sound pressure control signal consisting of a second frequency higher than the first frequency and an arbitrary duty ratio, and outputs these to a synthesis circuit via input / output ports corresponding to the first sound pressure control signal and the second sound pressure control signal, and the synthesis circuit synthesizes the first sound pressure control signal and the second sound pressure control signal to generate a third sound pressure control signal to drive the sounder.As a result, a sound pressure control device can be provided that is relatively inexpensive without using an SG port, and that can set the frequency and duty ratio of the pulse signal for each pulse, allowing for precise control of the sounder's sound pressure.

[0011] Furthermore, when the SG port is used, the duty ratio (sound pressure) is changed by interrupt processing at regular intervals, causing the sound pressure (amplitude) to change in a stepped manner, whereas the first mode has the advantage that the sound pressure (amplitude) can be changed smoothly, allowing for natural switching of sound pressure. Note that a "sounder" is an electronic sound generator that has an internal oscillator circuit and emits a buzzing sound when a specified electrical signal is input from the outside, and here it is taken to include not only piezoelectric buzzers but also electromagnetic buzzers and speakers.

[0012] In a second aspect dependent on the first aspect, the input / output port may be a general-purpose input / output port.

[0013] In the second mode, a sound pressure control signal is output using a general-purpose input / output port that is not assigned any special function, so that it is possible to control the sounder's sound pressure while effectively utilizing, for example, an unused GPIO (General-purpose input / output) port.

[0014] In a third aspect dependent on the first aspect, the synthesis circuit may be configured as a logical product circuit or a negative logical product circuit.

[0015] In the third aspect, the same function as an SG port can be realized by configuring the first sound pressure control signal and the second sound pressure control signal output via the general-purpose input / output port to be combined using a logical product circuit or a negative logical product circuit. Therefore, a sound pressure control device that controls the sound pressure of a sounder can be realized at a relatively low cost compared to using an SG port. Here, whether a logical product circuit is used as the combining circuit or a negative logical product circuit is used to configure the combining circuit depends on the circuits to be connected.

[0016] In a fourth aspect dependent on the first aspect, the synthesis circuit may be configured with a logical OR circuit or a NOR circuit.

[0017] In the fourth aspect, the same function as an SG port can be realized by configuring the first sound pressure control signal and the second sound pressure control signal output via the general-purpose input / output port to be combined using an OR circuit or a NOR circuit. Therefore, a sound pressure control device that controls the sound pressure of a sounder can be realized at a relatively low cost compared to using an SG port. Here, whether a logical OR circuit or a NOR circuit is used as the combining circuit depends on the circuits to be connected.

[0018] In a fifth aspect dependent on any of the first to fourth aspects, the synthesis circuit may include a drive circuit that drives the sounder with the third sound pressure control signal.

[0019] In the fifth aspect, the combining circuit also includes a drive circuit that drives the sounder, making it possible to sound the sounder without having to connect a drive circuit in front of the sounder. The drive circuit implemented in the combining circuit includes a pull-down resistor and a drive transistor that stabilize the input signal.

[0020] A sixth aspect according to the present invention is a sounder sound pressure control system having a sounder and a sound pressure control device that controls the sound pressure of the sounder by pulse width modulation, wherein the sound pressure control device has a microprocessor that generates a first sound pressure control signal consisting of a first frequency and a first duty ratio, and a second sound pressure control signal consisting of a second frequency higher than the first frequency and an arbitrary duty ratio, and outputs the first sound pressure control signal and the second sound pressure control signal via input / output ports corresponding to each of them, and a synthesis circuit that synthesizes the first sound pressure control signal and the second sound pressure control signal to generate a third sound pressure control signal and outputs the third sound pressure control signal to drive the sounder, and the sounder is driven by the third sound pressure control signal to output a blown sound.

[0021] In a sixth aspect, a sound pressure control system is composed of a sounder and a sound pressure control device, and the sound pressure control device controls the sound pressure of the sounder by pulse width modulation, and the microprocessor generates a first sound pressure control signal consisting of a first frequency and a first duty ratio, and a second sound pressure control signal consisting of a second frequency higher than the first frequency and an arbitrary duty ratio, and outputs these to a synthesis circuit via input / output ports corresponding to the first sound pressure control signal and the second sound pressure control signal, and the synthesis circuit synthesizes the first sound pressure control signal and the second sound pressure control signal to generate a third sound pressure control signal to drive the sounder and make it sound. This makes it possible to provide a sound pressure control system that is relatively inexpensive without using an SG port, and that can set the frequency and duty ratio of the pulse signal for each pulse, allowing for precise control of the sounder's sound pressure.

[0022] A seventh aspect according to the present invention is a method for controlling the sound pressure of a sounder by a sound pressure control device having a processor and a synthesis circuit, which controls the sound pressure of the sounder by pulse width modulation, comprising the steps of: the processor generating a first sound pressure control signal consisting of a first frequency and a first duty ratio, and a second sound pressure control signal consisting of a second frequency higher than the first frequency and an arbitrary duty ratio; the processor outputting the first sound pressure control signal and the second sound pressure control signal via input / output ports corresponding to each of the first sound pressure control signal and the second sound pressure control signal; and the synthesis circuit synthesizing the first sound pressure control signal and the second sound pressure control signal to generate a third sound pressure control signal, and outputting the third sound pressure control signal to drive the sounder.

[0023] In a seventh aspect, in a method for controlling the sound pressure of a sounder by pulse width modulation, a microprocessor generates a first sound pressure control signal consisting of a first frequency and a first duty ratio, and a second sound pressure control signal consisting of a second frequency higher than the first frequency and an arbitrary duty ratio, and outputs these to a synthesis circuit via input / output ports corresponding to the first sound pressure control signal and the second sound pressure control signal, and the synthesis circuit synthesizes the first sound pressure control signal and the second sound pressure control signal to generate a third sound pressure control signal to drive the sounder.This makes it possible to provide a sounder sound pressure control method that is relatively inexpensive without using an SG port, and that can set the frequency and duty ratio of the pulse signal for each pulse, allowing for precise control of the sounder sound pressure.

[0024] Those skilled in the art will easily understand that the exemplified embodiments according to the present invention can be further modified without departing from the spirit of the present invention. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of a sounder sound pressure control system including a sound pressure control device according to an embodiment of the present invention. [Figure 2]FIG. 2 is a flowchart showing the operation of the sound pressure control device according to the embodiment of the present invention. [Figure 3] FIG. 3 is a timing chart showing an example of the waveform of a sound pressure control signal generated by the sound pressure control device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] The best mode described below is used to facilitate understanding of the present invention, and therefore, those skilled in the art should be aware that the present invention is not unduly limited by the mode described below (hereinafter referred to as the present mode).

[0027] (Configuration of the embodiment) Please refer to Fig. 1. Fig. 1 is a block diagram showing an example of the configuration of a sounder sound pressure control system 100 including a sound pressure control device 10 of this embodiment.

[0028] The sound pressure control device 10 of this embodiment controls the sound pressure of a sounder 13 by pulse width modulation, and includes a microprocessor (hereinafter referred to as CPU 11) and a synthesis circuit 12. As shown in Fig. 3 described later, for example, the CPU 11 generates a first sound pressure control signal (see Fig. 3(a)) having a first frequency (2 KHz) and a first duty ratio (e.g., a duty ratio of 50%), and a second sound pressure control signal (see Fig. 3(b)) having a second frequency (30 KHz) higher than the first frequency and an arbitrary duty ratio (e.g., a duty ratio of 25%), and outputs the first sound pressure control signal and the second sound pressure control signal to the synthesis circuit 12 via input / output ports (general-purpose input / output terminals GPIO#1 and GPIO#2) corresponding to the first sound pressure control signal and the second sound pressure control signal, respectively.

[0029] The combining circuit 12 combines the first sound pressure control signal (see (a) in FIG. 3) and the second sound pressure control signal (see (b) in FIG. 3) to generate a third sound pressure control signal (see any of (c) to (f) in FIG. 3), and outputs the third sound pressure control signal to drive the sounder 13. As shown in FIG. 1, the combining circuit 12 is configured, for example, by a logical product circuit (hereinafter referred to as an AND circuit). As is well known, in an AND circuit, two transistors Tr1 and Tr2, whose A and B terminals are connected, determine whether or not a current flows to a resistor R3. Since the resistor R3 is connected in series to these transistors TR1 and Tr2, a current does not flow to the resistor R3 unless both transistors Tr1 and Tr2 are turned ON (if "1" is input to both input terminals A and B, the output is "1"). The resistors R1 and R2 are protective resistors for the transistors Tr1 and Tr2, respectively. The combining circuit 12 may be configured with a non-conjunction circuit (NAND circuit) instead of an AND circuit depending on the circuit configuration connected to the subsequent stage.

[0030] Incidentally, the third sound pressure control signal generated when the synthesis circuit 12 is configured with an AND circuit is, for example, a sound pressure control signal with a frequency of 2 kHz and a duty ratio of 25% (Duty=25%) as shown in (c) of Fig. 3, and the third sound pressure control signal output from the NAND circuit when the synthesis circuit 12 is configured with a NAND circuit is, for example, a sound pressure control signal with a frequency of 2 kHz and a duty ratio of 75% (Duty=75%) as shown in (d) of Fig. 3. Details will be described later.

[0031] Furthermore, the combining circuit 12 may be configured, for example, as a logical sum circuit (hereinafter referred to as an OR circuit). Although not shown, the OR circuit has a circuit configuration in which a resistor R3 is connected in series to two transistors connected in parallel. Whether or not a current flows to the resistor R3 is determined by two transistors connected to terminals A and B. Since these two transistors are connected in parallel, if either one is turned on, a current flows to the resistor R3 (if a "1" is input to either input terminal A or B, the output becomes "1"). If a current flows through the resistor R3, a voltage drop occurs across the resistor R3, and the output potential rises to near the power supply voltage VCC. Note that the combining circuit 12 may be configured with a negative logical sum circuit (NOR circuit) instead of an OR circuit, depending on the circuit configuration connected downstream.

[0032] Incidentally, the third sound pressure control signal generated when the synthesis circuit 12 is configured with an OR circuit is, for example, a sound pressure control signal with a frequency of 2 kHz and a duty ratio of 75% (Duty=75%) as shown in (e) of Fig. 3, and the third sound pressure control signal output from the NOR circuit when the synthesis circuit 12 is configured with a NOR circuit is, for example, a sound pressure control signal with a frequency of 2 kHz and a duty ratio of 25% (Duty=25%) as shown in (f) of Fig. 3. Details will be described later.

[0033] The combining circuit 12 may also be configured to include a driving circuit DRV (the portion surrounded by a dashed line in FIG. 1) of the sounder 13. The driving circuit DRV includes a driving transistor Tr3. Resistor R4 is a protective resistor, and resistor R5 is an adjustment resistor (volume). The combining circuit 12 may be configured not to include the driving circuit DRV (the driving circuit DRV may be omitted).

[0034] (Operation of the embodiment) Fig. 2 is a flowchart showing the operation of the sound pressure control device 10 of this embodiment, and Fig. 3 is a timing diagram showing an example of the waveform of a sound pressure control signal generated by the sound pressure control device 10 of this embodiment. Below, the operation of the sound pressure control device 10 of this embodiment shown in Fig. 1 will be described in detail with reference to Figs. 2 and 3. Note that in this description, the sounder 13 is implemented with a buzzer (piezoelectric sounder) that emits various sounds including warning sounds in response to the input of a PWM signal, for example, a Grove passive buzzer 107020109 by Speed.

[0035] The CPU 11 monitors a drive request for the sounder 13 issued by a program recorded in an internal or external memory (not shown) (step ST101). When a drive request for the sounder 13 is issued (step ST101 "YES"), the CPU 11 acquires a target voltage value (amplitude and duty ratio) also stored in the memory (step ST102). Next, the CPU 11 generates a first sound pressure control signal in accordance with the target voltage value, for example, as shown in Fig. 3(a) with a frequency of 2 kHz and a duty ratio of 50% (Duty = 50%) (step ST103), and also generates a second sound pressure control signal in accordance with the target voltage value, for example, as shown in Fig. 3(b) with a frequency of 30 kHz and a duty ratio of 50% (Duty = 50%) (step ST104). Next, the CPU 11 outputs the first sound pressure control signal to the synthesis circuit 12 via the GPIO terminal #1 (step ST105), and outputs the second sound pressure control signal to the synthesis circuit 12 via the GPIO terminal #2 (step ST106).

[0036] Next, the synthesis circuit 12 receives the first sound pressure control signal (frequency 2 kHz, duty ratio 50%) and the second sound pressure control signal (frequency 30 kHz, duty ratio 50%), and generates a third sound pressure control signal (for example, frequency 2 kHz, duty ratio 25%) by synthesizing the received first sound pressure control signal and second sound pressure control signal, which can drive the sounder 13 (here, a buzzer circuit) via the built-in drive circuit DRV.

[0037] Here, for example, suppose the duty ratio (duty) of the pulse of the buzzer drive waveform is changed to change the sound pressure of a 2 kHz single tone. In this case, for example, a duty ratio of 50% results in a high sound pressure (amplitude), and a duty ratio of 25% results in a low sound pressure (amplitude). In order to generate a pulse waveform with a duty ratio of 25% (25%) from a pulse waveform with a duty ratio of 50% (50%), for example, if a first sound pressure control signal with a duty ratio of 50% (50%) shown in Fig. 3(a) and a second sound pressure control signal with a duty ratio of 50% (50%) shown in Fig. 3(b) are synthesized by synthesis circuit 12 consisting of an AND circuit, a third sound pressure control signal with a duty ratio of 25% (25%) shown in Fig. 3(c) can be generated (step ST107).

[0038] On the other hand, when the synthesis circuit 12 is configured with a NOR circuit, it is possible to generate a third sound pressure control signal with a duty ratio of 25% (Duty=25%), as shown in Fig. 3(f), for example. When the synthesis circuit 12 is configured with a NAND circuit or an OR circuit, it is possible to generate a third sound pressure control signal with a duty ratio of 75% (Duty=75%), as shown in Fig. 3(d) or Fig. 3(e).

[0039] Finally, the buzzer circuit is driven by the third sound pressure control signal (one of (c) to (f) in FIG. 3) generated by the synthesis circuit 12 (step ST108), and as a result, the desired buzzer sound can be output from the piezoelectric buzzer (sounder 13) (step ST109).

[0040] In the sound pressure control device 10 of this embodiment, the sounder 13 has been described as outputting warnings and the like using electronic sounds, but it can also be used for other purposes, such as for in-vehicle use to output a sound that simulates the engine sound indicating that another vehicle is approaching.

[0041] (Effects of the embodiment) As described above, the sound pressure control device of this embodiment is, for example, as shown in FIG. 1, a sound pressure control device 10 that controls the sound pressure of a sounder 13 by pulse width modulation, and includes a microprocessor (CPU 11) that generates a first sound pressure control signal consisting of a first frequency and a first duty ratio (see 2 KHz, Duty = 50% in FIG. 3(a)) and a second sound pressure control signal consisting of a second frequency higher than the first frequency and an arbitrary duty ratio (see 30 KHz, Duty 25% in FIG. 3(b)), and outputs the first sound pressure control signal and the second sound pressure control signal via input / output ports (GPIO#1, GPIO#2) corresponding to them, and a synthesis circuit 12 that synthesizes the first sound pressure control signal and the second sound pressure control signal to generate a third sound pressure control signal (see, for example, 2 KHz, Duty 25% in FIG. 3(c)), and outputs the third sound pressure control signal to drive the sounder 13.

[0042] According to the sound pressure control device 10 of this embodiment, the sound pressure control device 10 controls the sound pressure of the sounder 13 by pulse width modulation, and is configured such that a microprocessor (CPU 11) generates a first sound pressure control signal consisting of a first frequency and a first duty ratio, and a second sound pressure control signal consisting of a second frequency higher than the first frequency and an arbitrary duty ratio, and outputs these to a synthesis circuit 12 via input / output ports (GPIO#1, GPIO#2) corresponding to the first sound pressure control signal and the second sound pressure control signal, respectively, and the synthesis circuit 12 synthesizes the first sound pressure control signal and the second sound pressure control signal to generate a third sound pressure control signal to drive the sounder 13. Therefore, it is possible to provide a sound pressure control device 10 that is relatively inexpensive without using an SG port, and that can set the frequency and duty ratio of the pulse signal for each pulse, thereby enabling precise sound pressure control of the sounder 13. Furthermore, when the SG port is used, the duty ratio (sound pressure) is changed by interrupt processing at regular intervals, causing the sound pressure (amplitude) to change in a stepped manner, whereas the first mode has the advantage that the sound pressure (amplitude) can be changed smoothly, allowing for natural switching of sound pressure.

[0043] Furthermore, according to the sound pressure control device 10 of this embodiment, a sound pressure control signal is output using a general-purpose input / output port that is not assigned any special function, so that it is possible to control the sound pressure of the sounder 13 while effectively utilizing, for example, unused GPIO ports (GPIO#1, GPIO#2), etc.

[0044] Furthermore, according to the sound pressure control device 10 of this embodiment, the first sound pressure control signal and the second sound pressure control signal output via the general-purpose input / output ports (GPIO#1, GPIO#2) are combined using a logical product circuit (AND circuit) or a negative logical product circuit (NAND circuit), thereby realizing the same function as an SG port, and therefore the sound pressure control device 10 that controls the sound pressure of the sounder 13 can be realized at a relatively low cost compared to when an SG port is used. Here, whether a logical product circuit is used as the combining circuit 12 or a negative logical product circuit is used to configure the combining circuit 12 depends on the circuits to be connected.

[0045] Furthermore, according to the sound pressure control device 10 of this embodiment, the first sound pressure control signal and the second sound pressure control signal output via the general-purpose input / output ports (GPIO#1, GPIO#2) are synthesized using a logical sum circuit (OR circuit) or a negative logical sum circuit (NOR circuit), thereby realizing the same function as an SG port, and therefore the sound pressure control device 10 that controls the sound pressure of the sounder 13 can be realized at a relatively low cost compared to when an SG port is used. Here, whether a logical sum circuit is used as the synthesis circuit 12 or a negative logical sum circuit is used to configure the synthesis circuit 12 depends on the circuits to be connected.

[0046] Furthermore, according to the sound pressure control device 10 of this embodiment, the synthesis circuit 12 also includes a drive circuit DRV that drives the sounder 13, so it is possible to make the sounder 13 sound without connecting a drive circuit upstream of the sounder 13. The drive circuit DRV implemented in the synthesis circuit 12 includes a drive transistor (for example, see Tr3 in FIG. 1).

[0047] The sounder sound pressure control system of this embodiment is, for example, as shown in FIG. 1, a sounder sound pressure control system 100 having a sounder 13 and a sound pressure control device 10 that controls the sound pressure of the sounder 13 by pulse width modulation. The sounder sound pressure control system 100 includes a sound pressure control device 10 that generates a first sound pressure control signal having a first frequency and a first duty ratio (see 2 kHz, duty = 50% in (a) of FIG. 3) and a second sound pressure control signal having a second frequency higher than the first frequency and an arbitrary duty ratio (see 30 kHz, duty 25% in (b) of FIG. 3), and a microprocessor (CPU 11) that outputs the first sound pressure control signal and the second sound pressure control signal via input / output ports (GPIO #1, GPIO #2) corresponding to the first sound pressure control signal and the second sound pressure control signal, respectively; and a synthesis circuit 12 that synthesizes the first sound pressure control signal and the second sound pressure control signal to generate a third sound pressure control signal (see, for example, 2 kHz, duty 25% in (c) of FIG. 3), and outputs the third sound pressure control signal to drive a sounder 13. The sounder 13 is driven by the third sound pressure control signal to output a blown sound.

[0048] According to the sounder sound pressure control system 100 of this embodiment, the sound pressure control system 100 is composed of a sounder 13 and a sound pressure control device 10, and the sound pressure control device 10 controls the sound pressure of the sounder 13 by pulse width modulation. A microprocessor (CPU 11) generates a first sound pressure control signal consisting of a first frequency and a first duty ratio, and a second sound pressure control signal consisting of a second frequency higher than the first frequency and an arbitrary duty ratio, and outputs these to a synthesis circuit 12 via input / output ports (GPIO#1, GPIO#2) corresponding to the first sound pressure control signal and the second sound pressure control signal, respectively. The synthesis circuit 12 then synthesizes the first sound pressure control signal and the second sound pressure control signal to generate a third sound pressure control signal, which drives the sounder 13 and causes it to sound. Therefore, it is possible to provide a sound pressure control system 100 that is relatively inexpensive without using an SG port, and that can set the frequency and duty ratio of the pulse signal for each pulse, thereby enabling precise sound pressure control of the sounder.

[0049] The sound pressure control method of the sounder of this embodiment is, for example, as shown in Fig. 1, a sound pressure control method of the sounder 13 by a sound pressure control device 10 having a processor (CPU 11) and a synthesis circuit 12, which controls the sound pressure of the sounder 13 by pulse width modulation. The sound pressure control method of the sounder includes, for example, as shown in Fig. 2, steps (ST101 to ST104) in which the processor (CPU 11) generates a first sound pressure control signal consisting of a first frequency and a first duty ratio (see 2 KHz, Duty = 50% in Fig. 3(a)) and a second sound pressure control signal consisting of a second frequency higher than the first frequency and an arbitrary duty ratio (see 30 KHz, Duty 25% in Fig. 3(b)). a step in which the processor (CPU 11) outputs the first sound pressure control signal and the second sound pressure control signal via the corresponding input / output ports (GPIO#1, GPIO#2) (see ST105, ST106); a step in which the synthesis circuit 12 synthesizes the first sound pressure control signal and the second sound pressure control signal to generate a third sound pressure control signal (see, for example, 2 kHz, duty 25% in (c) of FIG. 3) and outputs the third sound pressure control signal to drive the sounder 13 (see ST107, ST109); See ST107 to ST109).

[0050] According to the sounder sound pressure control method of this embodiment, a microprocessor (CPU 11) generates a first sound pressure control signal consisting of a first frequency and a first duty ratio, and a second sound pressure control signal consisting of a second frequency higher than the first frequency and an arbitrary duty ratio, and outputs these to a synthesis circuit 12 via input / output ports (GPIO #1, GPIO #2) corresponding to the first sound pressure control signal and the second sound pressure control signal, respectively, and the synthesis circuit 12 synthesizes the first sound pressure control signal and the second sound pressure control signal to generate a third sound pressure control signal to drive the sounder 13. Therefore, a sounder sound pressure control method can be provided that is relatively inexpensive without using an SG port, and that allows the frequency and duty ratio of the pulse signal to be set for each pulse, thereby enabling precise sound pressure control of the sounder.

[0051] The present invention is not limited to the above-described exemplary embodiments, and those skilled in the art will be able to easily modify the above-described exemplary embodiments to the extent that they fall within the scope of the claims. [Explanation of symbols]

[0052] 10... Sound pressure control device, 11... Microprocessor (CPU), 12... Synthesis circuit, 13... Sounder, 100... Sounder sound pressure control system

Claims

1. A sound pressure control device that controls the sound pressure of a sounder by pulse width modulation, a first sound pressure control signal having a first frequency and a first duty ratio; a second sound pressure control signal having a second frequency higher than the first frequency and an arbitrary duty ratio; and outputting the first sound pressure control signal and the second sound pressure control signal via input / output ports corresponding to the first sound pressure control signal and the second sound pressure control signal; a synthesis circuit that synthesizes the first sound pressure control signal and the second sound pressure control signal to generate a third sound pressure control signal and outputs the third sound pressure control signal to drive the sounder.

2. The input / output port is 2. The sound pressure control device according to claim 1, wherein the sound pressure control device is a general-purpose input / output port.

3. The synthesis circuit 2. The sound pressure control device according to claim 1, which is configured by a logical product circuit or a negative logical product circuit.

4. The synthesis circuit 2. The sound pressure control device according to claim 1, which is configured by a logical OR circuit or a NOR circuit.

5. The synthesis circuit 2. The sound pressure control device according to claim 1, further comprising a drive circuit for driving said sounder with said third sound pressure control signal.

6. A sounder sound pressure control system having a sounder and a sound pressure control device that controls the sound pressure of the sounder by pulse width modulation, The sound pressure control device includes: a microprocessor that generates a first sound pressure control signal having a first frequency and a first duty ratio, and a second sound pressure control signal having a second frequency higher than the first frequency and an arbitrary duty ratio, and outputs the first sound pressure control signal and the second sound pressure control signal via input / output ports corresponding to the first sound pressure control signal and the second sound pressure control signal; a synthesis circuit that synthesizes the first sound pressure control signal and the second sound pressure control signal to generate a third sound pressure control signal and outputs the third sound pressure control signal to drive the sounder, The sounder is a sounder sound pressure control system that is driven by the third sound pressure control signal to output a blowing sound;

7. A sound pressure control method for a sounder using a sound pressure control device having a processor and a synthesis circuit, the sound pressure control device controlling the sound pressure of the sounder by pulse width modulation, comprising: the processor: generating a first sound pressure control signal having a first frequency and a first duty ratio, and a second sound pressure control signal having a second frequency higher than the first frequency and an arbitrary duty ratio; the processor: outputting the first sound pressure control signal and the second sound pressure control signal via input / output ports corresponding to the first sound pressure control signal and the second sound pressure control signal; The synthesis circuit generating a third sound pressure control signal by combining the first sound pressure control signal and the second sound pressure control signal, and outputting the third sound pressure control signal to drive the sounder.

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