JPH06118964A - Buzzer sounding device - Google Patents

Abstract

PURPOSE:To secure the maximum sound pressure of a buzzer by using a frequency, swept in a frequency range corresponding to variance in resonance frequency characteristics of the buzzer, as the frequency of an applied voltage. CONSTITUTION:A 1st saw-tooth wave generated by a saw-tooth wave generating circuit 8 is inputted to a sweep generating circuit 9 and then a 2nd saw-tooth wave is generated. A sweep generating circuit 9 determines a reference voltage V1 (V1 < V2min) and is set when the voltage of the 2nd saw-tooth waveform becomes lower than the reference voltage V1 and reset when the voltage of the 2nd saw-tooth waveform reaches a threshold value. A rectangular wave which is generated by the sweep generating circuit 9 and swept is inputted to a driving circuit 10, which outputs and applies a voltage swept in frequency to a lower frequency to the buzzer 11. Then the buzzer 11 vibrates at a resonance frequency corresponding to the frequency of the applied voltage swept at a certain period by the application of the frequency to sound with specific sound pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a buzzer sounding device used for alarms and the like, and more particularly to a buzzer sounding device whose sound pressure changes.

[0002]

2. Description of the Related Art Conventionally, a buzzer blowing device used for an alarm or the like changes the sound pressure of the buzzer by changing the voltage. Such a technique is disclosed in JP-A-3-
It is disclosed in Japanese Patent Publication No. 276192. Figure 8
Will be explained. A transistor Q, which is an amplifying element, generates an oscillation signal output from the oscillation circuit 14 at a fixed frequency.
It is amplified by 1 and the buzzer 11 outputs a warning sound. At that time, the power supply voltage level VS supplied to the transistor Q1 is continuously changed by the voltage level control circuit 15. As a result, the sound pressure of the warning sound output from the buzzer 11 is continuously changed.

[0003]

FIG. 5 is a diagram showing variations in resonance frequency characteristics of individual buzzers. As shown in FIG. 5, the resonance frequency characteristic of each buzzer inevitably varies in the horizontal axis direction representing the frequency while maintaining its waveform due to manufacturing errors or the like. Therefore, when a voltage of a fixed frequency is applied to such a buzzer, a deviation from the resonance frequency of the buzzer that can secure a predetermined sound pressure occurs, and the maximum value of the sound pressure of each buzzer becomes a predetermined value. There was a problem that the value could not be secured. Therefore, an object of the present invention is to apply a voltage at a swept frequency to match the frequency of the applied voltage with the resonance frequency at which the sound pressure of the buzzer becomes a predetermined level or higher, and set the sound pressure of each buzzer to a predetermined value. To secure above the level.

[0004]

In order to solve the above problems, in the present invention, in a buzzer sounding device used for an alarm or the like, a buzzer whose sound pressure changes depending on the frequency of an applied voltage, and the frequency And a drive means for outputting a voltage at the frequency swept by the sweep means and supplying it as an applied voltage to the buzzer.

[0005]

By the above means, the frequency of the applied voltage is changed with time by sweeping the frequency to the frequency of the applied voltage in the range including the resonance frequency at which the sound pressure of the buzzer becomes a predetermined level or more. Then, the buzzer is driven at the resonance frequency corresponding to the frequency of the applied voltage, and the sound pressure corresponding to the resonance frequency is output from the buzzer based on the resonance frequency characteristic indicating the relationship between the resonance frequency of the buzzer and the sound pressure.

[0006]

EXAMPLE A first example of the present invention will be described below.
FIG. 1 is an overall block diagram of the first embodiment and relates to a key removal forgetting warning buzzer. The power supply circuit 7 is a circuit for making the fluctuating voltage from the battery 4 a constant voltage and supplying it to each circuit. Ignition switch 1 is O
When the key unlock switch 2 is ON in the FF and the driver side door courtesy switch 3 is ON, the key unlock switch ON signal and the driver side door courtesy switch ON signal are input to the input circuit 6, and the buzzer ON signal is input from the input circuit 6. Is output. Here, the key removal forgetting warning buzzer is used, but a speed warning buzzer or a light erasing forgetting buzzer may be used and is not particularly limited.

When the buzzer ON signal is input to the sawtooth wave generation circuit 8 which is a part of the sweep means, the first sawtooth wave having a cycle S in which the frequency of the applied voltage as shown in FIG. 2 sweeps. Is generated. The sawtooth wave generated here is a rechargeable sawtooth wave, which is created by gradually charging with time and discharging at a moment when the voltage reaches V2max. The vertical axis represents voltage V, the horizontal axis represents time t, and the apex of the wave is voltage V2.
max, and the minimum voltage is V2min> 0. The cycle S of the sawtooth wave is set so as to fall within a range in which variations in resonance frequency characteristics of individual buzzers are taken into consideration.

When the first sawtooth wave is output from the sawtooth wave generation circuit 8, it is then input to the sweep generation circuit 9 as the sweep means.

The sweep generation circuit 9 will be briefly described below. The sweep generation circuit 9 generates a second sawtooth wave based on the first sawtooth wave, and further to the second sawtooth wave.
This is a circuit that outputs a rectangular wave whose period gradually sweeps from a sawtooth wave.

When the first sawtooth wave generated by the sawtooth wave generation circuit 8 is input to the sweep generation circuit 9, a second sawtooth wave as shown in FIG. 3 is generated. Similar to FIG. 2, the vertical axis represents the voltage V and the horizontal axis represents the time t, and the apex of the wave is the voltage V2, which changes according to the waveform of the first sawtooth wave.
That is, the second sawtooth wave is thresholded at the voltage level V2 of the first sawtooth wave, and its voltage and period increase where the voltage level V2 of the first sawtooth wave increases, and the voltage V2 increases. Reaches a minimum value of V2min, then takes a minimum value and increases again in accordance with the voltage V2.

A rectangular wave as shown in FIG. 4 is created based on the second sawtooth wave. An RS flip-flop circuit is incorporated in the sweep generation circuit 9. First, a reference voltage V1 (V1 <V2min) is determined, and SET is applied when the voltage of the second sawtooth wave becomes equal to or lower than the reference voltage V1, RESET is applied when the voltage of the second sawtooth wave reaches the threshold voltage V2.
Then, a rectangular wave as shown by Q in FIG. 4 is output from the output terminal, and the oscillation signal is turned on when the rising edge of this rectangular wave is observed.
When turned off N, the sweep generation circuit 9 outputs a rectangular wave such as OUT in FIG.

The output rectangular wave has a period T of T1, T
Sweep to 2, T3, ..., TN, and return to T1 again after sweeping to TN. That is, T1 + T
It is repeated in a cycle of 2 + T3 + ... + TN = S.

The sweeping rectangular wave generated by the sweep generating circuit 9 is input to a drive circuit 10 as a drive means and has frequencies of 1 / (T1) and 1 / (T
2), ..., 1 / (TN), and a voltage that sweeps to a lower frequency in that order is output and applied to the buzzer 11. At that time, since T1 is the smallest cycle, 1 / (T
1) is the maximum frequency of the applied voltage.

Accordingly, the frequency range to be swept can be specified by properly determining the sweep cycle S and the maximum frequency 1 / (T1) of the applied voltage. The predetermined frequency range to be swept is the range that includes the frequency at which the sound pressure above the desired sound pressure level can be output regardless of which buzzer is used, considering variations in the resonance frequency characteristics of individual buzzers. is there. That is, it is assumed that the two resonance frequency characteristics shown in FIG. 5 are the most varied due to variations in individual buzzers, and the minimum desired sound pressure level is 90 dB. It shows a range including frequencies from 740 Hz to 750 Hz in which both the sound pressure levels of the resonance frequency characteristics exceed 90 dB.

When the frequency of the applied voltage that has been swept at a constant period S is applied to the buzzer 11, the buzzer 11 vibrates at the resonance frequency corresponding to the frequency of the applied voltage and blows at a sound pressure corresponding to the resonance frequency. .

With the configuration shown in the first embodiment, the buzzer 1 applies a voltage having a frequency swept repeatedly within a predetermined range.
By applying this to No. 1, it is possible to emit a sound with a sound pressure corresponding to the resonance frequency of the buzzer 11. At this time, even if the resonance frequency characteristics of the individual buzzers vary due to manufacturing errors or the like, if a voltage of a frequency swept within a range including the resonance frequency above a predetermined sound pressure level is applied, the buzzer 11 It is possible to ensure that the maximum sound pressure output from the device is equal to or higher than a predetermined level and to make a sound.

This time, the direction of sweeping is set to the frequency from high to low, but it does not necessarily have to be in this direction, and the frequency may be changed from low to high. In this case, if the first sawtooth wave is not a charge-type sawtooth wave but a discharge-type sawtooth wave, it can be easily performed. Any waveform may be used in this way as long as the frequency of the applied voltage can be swept within a predetermined range.

Next, a second embodiment of the present invention will be described. Low range A of the buzzer with frequency characteristics as shown in Fig. 6
By sweeping the frequency of the applied voltage in each of the high tone range and the high tone range B, it is possible to emit two tones. To this end, a frequency switching circuit 12 as shown in FIG. 7 may be connected between the sawtooth wave generating circuit 8 and the sweep generating circuit 9 in the first embodiment of the present invention.

In the case of sounding in the low tone range A as the key forgetting warning buzzer and in the high tone range B as the speed warning buzzer, the speed warning switch 13 is provided in addition to the switch used in the first embodiment. The input circuit 6 discriminates the input of, and the frequency switching circuit 12 outputs a signal for supporting in which sound range the sound is to be emitted.

In response to this signal, the frequency switching circuit 12 changes the voltage V2 of the first sawtooth wave to change the voltage division ratio with the voltage of the second sawtooth wave, thereby generating a rectangle in the sweep generation circuit 9. Change the wave period,
The frequency of the voltage applied from the drive circuit 10 to the buzzer 11 is switched so that it falls within the range of the low sound range A and the high sound range B. The bass range A and the treble range B are set in advance so as to include a range having a predetermined sound pressure or higher in consideration of variations in resonance frequency characteristics of individual buzzers.

Here, the key removal forgetting warning buzzer and the speed warning buzzer are configured, but the invention is not particularly limited as long as the warning sound is not emitted at the same time. It is also possible to give a warning by sweeping not only in two places but also in a plurality of ranges and blowing a plurality of tones.

By doing so, it has been difficult to secure a predetermined sound pressure level because the sound pressure change of the resonance frequency characteristic, especially in the high frequency band, has been large until now, and a single buzzer sounds in a plurality of frequency bands. However, in the second embodiment of the present invention, by sweeping the frequency of the applied voltage in a plurality of frequency bands, a predetermined sound pressure is secured and a plurality of frequency bands can be obtained with one buzzer. Can be made to sound.

[0023]

In the buzzer sounding device of the present invention, even if the resonance frequency characteristic of the buzzer varies due to manufacturing errors or the like, the frequency swept in the frequency range corresponding to the variation is used as the frequency of the applied voltage. As a result, the maximum sound pressure of the buzzer can be secured at a predetermined level or higher.

[Brief description of drawings]

FIG. 1 is an overall block diagram of a first embodiment of the present invention.

FIG. 2 is a diagram showing a sawtooth wave generated by the sawtooth wave generation circuit according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a swept sawtooth wave generated by the sweep generation circuit in the first embodiment of the present invention.

FIG. 4 is a time chart of a rectangular wave generated by the sweep generation circuit according to the first embodiment of the present invention.

FIG. 5 is a diagram showing variations in resonance frequency characteristics of individual buzzers.

FIG. 6 is a wide-range frequency characteristic diagram of the buzzer.

FIG. 7 is an overall block diagram of a second embodiment of the present invention.

FIG. 8 is a basic configuration diagram in the related art.

[Explanation of symbols]

 1 ・ ・ ・ Ignition switch 2 ・ ・ ・ Key unlock switch 3 ・ ・ ・ Driver side door courtesy switch 4 ・ ・ ・ Battery 6 ・ ・ ・ Input circuit 7 ・ ・ ・ Power supply circuit 8 ・ ・ ・ Sawtooth wave generation circuit (sweep means) ) 9 ... Sweep generation circuit (sweep means) 10 ... Drive circuit (drive means) 11 ... Buzzer 12 ... Frequency switching circuit 13 ... Speed warning switch

Claims (1)

[Claims] 1. A buzzer sounding device used for an alarm or the like, a buzzer whose sound pressure changes according to the frequency of an applied voltage, a sweeping means for sweeping the frequency within a predetermined frequency range, and a sweeping means for sweeping by the sweeping means. A buzzer sounding device, comprising: drive means for outputting a voltage at a frequency and supplying it as an applied voltage to the buzzer.