JP2010049605A - Alarm - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure sufficient sound pressure corresponding to a frequency change when a sweep sound is output, and simultaneously reduce current consumption of a speaker. <P>SOLUTION: An alarm 10 outputs a sweep sound whose frequency changes in a predetermined range with lapse of time from a speaker 46 as an alarm when detecting a fire. A reference current setting part 54 sets a driving current as a reference current Ir, the driving current flowing when a predetermined amplitude voltage Vr having a predetermined frequency having a high sound pressure in the speaker 46 and having a high impedance is applied. A PWM processing part 56 outputs a PWM pulse string in which a duty ratio is set so that the driving current of the speaker 46 is kept in the vicinity of the reference current Ir, converts the PWM pulse string to a sound signal via a low pass filter 42, and then amplifies the sound signal by an amplifier 44 to output from the speaker 46. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to an alarm device that is installed in a general house or the like and monitors and alarms a fire by battery drive.

  2. Description of the Related Art Conventionally, residential alarm devices (hereinafter referred to as “residential alarm devices”) that detect and warn of abnormalities such as fires and gas leaks in homes have become popular.

  In such a house alarm, a sensor unit and an alarm unit are integrated in the house alarm, and a fire alarm is issued when a fire is detected. Therefore, it is easy to install and inexpensive, and it has become widespread with the obligatory installation in ordinary houses.

  As an alarm when a conventional house alarm detects a fire, for example, an alarm sound such as “It ’s a fire. Here, the first half “Peepy” is called a sweep sound, and the frequency is linearly changed with respect to time in a range that is easy to hear, such as 2 to 3 KHz.

  For alarm sound output composed of sweep sound and voice message, prepare ROM which stores voice data, convert voice data read from ROM into PWM pulse, PWM pulse (pulse width modulation pulse) through low pass filter It is converted into a sound signal waveform by passing it through, amplified by an amplifier, and then output from a speaker.

  Such a PWM conversion method that converts audio data into PWM pulses and outputs an alarm sound does not require an expensive AD converter for analog conversion of audio data, and can output audio at low cost.

In recent years, as a result of efforts to reduce the power consumption of residential alarms, a long battery life of, for example, 10 years or more is guaranteed, and no battery replacement is required during that period. When the battery is used for a long time and nears the end of its battery life and a decrease in battery voltage is detected, an alarm for notifying that the battery has run out is issued.

JP 2005-44317 A JP 2004-54356 A

  By the way, in the speaker used for the conventional alarm device, the impedance of the speaker tends to change depending on the frequency, and the impedance tends to increase at a frequency at which the sound pressure increases.

  For this reason, if a drive voltage with a constant amplitude and frequency that changes in order to output a sweep sound is applied to the speaker, a large amount of current flows because the impedance is low in the frequency band where the sound pressure is not high, and this wastes current. The

  Also, if the amplitude of the drive voltage is increased to ensure sufficient sound pressure, the peak current increases in the frequency band where the sound pressure is not high, resulting in a large battery voltage drop and a short battery life. There is also.

It is an object of the present invention to provide an alarm device that can secure a sufficient sound pressure with respect to a frequency change when outputting a sweep sound and at the same time reduce a speaker current consumption.

The present invention provides an alarm device for outputting a sweep sound whose frequency changes within a predetermined range as time passes when an abnormality is detected from a speaker as an alarm sound.
A reference current setting unit that sets, as a reference current Ir, a drive current that flows when a drive voltage Vr with a predetermined amplitude having a predetermined frequency with high sound pressure and high impedance in the speaker is applied;
A PWM processing unit that outputs a PWM pulse train in which a duty ratio is set so as to keep the driving current of the speaker near the reference current Ir;
An acoustic output circuit unit for amplifying the PWM pulse train after passing through a low-pass filter and converting it to an audio signal;
Is provided.

Here, the PWM processing unit
An amplitude voltage data setting unit for setting speaker amplitude voltage data that keeps the speaker drive current near the reference current Ir with respect to a change in frequency;
A frequency setting unit for setting a frequency that linearly changes in a predetermined frequency range over time;
A PWM converter having a duty ratio converted from the amplitude voltage data of the amplitude voltage data setting unit and generating and outputting a PWM pulse having a linearly changing frequency set by the frequency setting unit;
Is provided.

  The amplitude voltage data setting unit divides the product of the reference current Ir and the predetermined amplitude voltage Vr (Ir × Vr) by the drive current distribution when a sweep sound is output from the speaker by adding the predetermined amplitude voltage Vr over the frequency range. The amplitude voltage data distribution over the frequency range is calculated, and when the sweep sound is output, a PWM pulse having a duty ratio according to the amplitude voltage data distribution according to the frequency change is output to the PWM converter, and the driving current of the speaker is calculated. Hold at reference current.

  Further, the amplitude voltage data setting unit adds the product (Ir × Vr) of the reference current Ir and the predetermined amplitude voltage Vr over the frequency range and adds the predetermined amplitude voltage Vr to output a sweep sound from the speaker. A division function that approximates the amplitude voltage distribution obtained by division is obtained, and when a sweep sound is output, a PWM pulse having a duty ratio according to the amplitude voltage calculated by the division function is output to the PWM conversion unit according to the frequency change. The speaker drive current is kept near the reference current.

Another form of the present invention is an alarm device that outputs a sweep sound whose frequency changes within a predetermined range as time passes when an abnormality is detected from a speaker as an alarm sound.
A reference current setting unit for setting, as a reference current Ir, a drive current that flows when a drive voltage of a predetermined amplitude Vr having a predetermined frequency with high sound pressure and high impedance of the speaker is applied;
A sweep sound output processing unit for controlling an amplitude voltage applied to the speaker so as to keep the speaker drive current accompanying the frequency change in the vicinity of the reference current Ir when the sweep sound is output;
Is provided.

  Here, the sweep sound output processing unit adds the product (Ir × Vr) of the reference current Ir and the predetermined amplitude voltage Vr over the frequency range, and adds a predetermined amplitude voltage over the frequency range to generate a sweep sound from the speaker. The amplitude voltage distribution obtained by the division is held, and when the sweep sound is output, the speaker drive current is held at the reference current by applying the amplitude voltage according to the amplitude voltage distribution to the speaker as the frequency changes.

The sweep sound output processing unit divides the product of the reference current Ir and the predetermined amplitude voltage Vr (Ir × Vr) by the drive current distribution when the sweep sound is output from the speaker by adding the predetermined amplitude voltage over the frequency range. A piecewise function that approximates the obtained amplitude voltage distribution is held, and when a sweep sound is output, the speaker drive current is held near the reference current by adding the amplitude voltage calculated by the piecewise function to the speaker as the frequency changes To do.

  According to the present invention, a driving current having a high sound pressure and a low current consumption in a sweep frequency range is set as a reference current, and an impedance with a low sound pressure is not high with respect to a voltage amplitude at a frequency that gives the reference current. By controlling the amplitude voltage applied to the speaker so as to reduce the voltage amplitude in the frequency band, the reference current is not greatly exceeded with respect to the frequency change, and the maximum sound pressure is reliably maintained at the same time while reducing the peak current. The output of the sweep sound can be extended, and the battery life can be extended.

In addition, the control of the amplitude voltage applied to the speaker that becomes smaller in the low-impedance frequency band can be realized easily and easily by controlling the duty ratio of the PWM pulse, and the amplitude voltage distribution in the sweep frequency range can be determined by ROM data or piecewise function. By setting, the ROM capacity can be greatly reduced as compared with the case where the sound data of the sweep sound is stored in the ROM.

  FIG. 1 is an explanatory view showing the appearance of a house alarm device according to the present invention. FIG. 1 (A) shows a front view and FIG. 1 (B) shows a side view.

  In FIG. 1, the residential alarm 10 according to the present embodiment includes a cover 12 and a main body 14. In the center of the cover 12, a smoke detecting section 16 having a smoke inlet is opened around it so that a fire is detected when smoke from the fire reaches a predetermined concentration.

  An acoustic hole 18 is provided on the lower left side of the smoke detector 16 provided in the cover 12, and a speaker is built in behind this so that an alarm sound or a voice message can be output. An alarm stop switch 20 is provided below the smoke detector 16. The alarm stop switch 20 also functions as an inspection switch.

  An LED 22 is arranged inside the alarm stop switch 20 as indicated by a dotted line. When the LED 22 is lit, the LED 22 is lit through the switch cover portion of the alarm stop switch 20 so that the lighting state of the LED 22 can be seen from the outside. Yes.

  Also, a mounting hook 15 is provided on the upper back side of the main body 14, and a screw or the like is screwed into the wall of the room to be installed, and the mounting hook 15 is attached to this screw, so that the residential alarm 10 can be installed on the wall surface. it can.

  The house alarm 10 is installed on, for example, a wall surface of a living room or a bedroom of a house, and in the event of a fire, the fire is detected and an alarm is started. Detecting this fire and initiating an alarm is referred to as “reporting” at the home alarm.

  As an alarm sound of the residence warning device 10-4 when a fire is detected, for example, “Peepy” is continuously output as a sweep sound. At the same time, the LED 22 blinks or blinks. If the alarm stop switch 20 is operated in a state in which the house alarm 10 is emitting an alarm sound, the alarm sound is stopped and the LED 22 is turned off.

  In addition, the resident alarm 10 has a failure monitoring function. When a failure is detected, for example, an alarm sound such as “beep” is intermittently output every predetermined time, and the LED 22 is turned on instantaneously to cause a failure. Is notified. The failure alarm output from the home alarm 10 can be stopped by operating the alarm stop switch 20.

  The failure that is detected and alarmed by the home alarm 10 is mainly a battery capacity decrease alarm (battery exhaustion alarm) that detects and alarms a decrease in battery voltage. Appropriate failure alarms such as sensor failures are included.

  FIG. 2 is a block diagram showing an embodiment of a residential alarm according to the present invention. The home alarm device 10 includes a CPU 24, and a sensor unit 26, a notification unit 28, an operation unit 30, an EEPROM 32, a RAM 35, a transfer unit 36, and a battery power source 40 are provided for the CPU 24.

  In the present embodiment, the sensor unit 26 is provided with a smoke detection unit 16 and outputs a smoke detection signal corresponding to the smoke density to the CPU 24. In addition to the smoke detector 16, the sensor unit 26 may be provided with a thermistor that detects a temperature due to a fire. Further, in the case of a residence warning device for gas leak monitoring, a gas leak sensor is provided in the sensor unit 26.

  The notification unit 28 is provided with a speaker 46 driven by an acoustic output circuit unit including a low-pass filter 44 and an amplifier 44, and an LED 22 driven by a display circuit unit 48.

  The low-pass filter 42 is a simple filter composed of a capacitor and a resistor. The low-pass filter 42 converts the alarm sound PWM pulse output from the CPU 24 into a sound signal waveform that is smoothly converted by removing components exceeding the upper limit frequency of the sound frequency band. After being amplified by the amplifier 44, the signal is output from the speaker 46. The LED 22 displays an abnormality or failure such as a fire by blinking, blinking, or lighting.

  The operation unit 30 is provided with an alarm stop switch 20. When the alarm stop switch 20 is operated, the alarm sound flowing from the residential alarm 10 can be stopped. The alarm stop switch 20 also serves as an inspection switch in the present embodiment.

  The alarm stop switch 20 is effective when an alarm sound is output from the notification unit 28 through the speaker 46. On the other hand, the alarm stop switch 20 functions as an inspection switch in a normal monitoring state in which no alarm sound is output. When the inspection switch is pressed, a notification voice message or the like is output from the notification unit 28.

  The battery power source 40 uses, for example, an alkaline dry battery having a predetermined number of cells, supplies a battery voltage of, for example, 5.0 volts as the rated voltage, and reduces the power consumption of the entire circuit unit in the residential alarm 10 as the battery capacity. Ensures a battery life of about 10 years.

  The CPU 24 is provided with an abnormality monitoring unit 50 and a sweep sound processing unit 52 as functions realized by executing the program. The sweep sound processing unit 52 is provided with functions of a speaker reference current setting unit 54 and a PWM processing unit 56.

  When the smoke detection signal from the smoke detector 16 provided in the sensor unit 26 exceeds the fire level and detects a fire, the abnormality monitoring unit 50 sweeps, for example, “Peepy” as an alarm sound from the speaker 46 of the notification unit 28. The sound is repeatedly output, and the LED 22 of the notification unit 28 is blinked, for example.

  The sweep sound processing unit 52 generates and outputs a PWM pulse train corresponding to the sweep sound, converts it into a speech waveform signal having a substantially sine waveform through the filter 42, and then amplifies it by the amplifier 44 and outputs it from the speaker 46.

  The reference current setting unit 54 provided in the sweep sound processing unit 52 sets, as the reference current Ir, the drive current that flows when a predetermined amplitude voltage Vr having a predetermined frequency fp with high sound pressure and high impedance in the speaker 46 is applied. To do.

  The PWM processing unit 56 outputs a PWM pulse train in which the duty ratio is set so as to keep the driving current of the speaker 46 in the vicinity of the reference current Ir at the time of outputting the sweep sound, passes through the low-pass filter 42, and converts it into an audio signal. Amplified at 44 and output from the speaker 46.

  FIG. 3 is a block diagram showing an embodiment of the PWM processing unit 56 of FIG. 2, and functions realized by execution of a program by the CPU 24.

  3, the PWM processing unit 56 is provided with an amplitude voltage data setting unit 58, a register 60, a frequency setting unit 62, a register 64, a PWM conversion unit 66, and a control unit 68.

  The amplitude voltage data setting unit 58 is an amplitude voltage that maintains the speaker drive current in the vicinity of the reference current Ir that flows at a predetermined frequency fp where the sound pressure of the speaker is high and the impedance is high with respect to the change in frequency in the sweep frequency range with time. Data is set in the PWM converter 66 via the register 60.

  The amplitude voltage data 35 set by the amplitude voltage data setting unit 58 is stored in the EEPROM 32 in advance, and the amplitude voltage data setting unit 58 sequentially reads the amplitude data 35 of the EEPROM 32 and sets it in the register 60 when the sweep sound is output. To do.

  The frequency setting unit 60 sets, for example, a frequency that changes linearly within a predetermined sweep frequency range in the PWM conversion unit 66 via the register 64 with the passage of time during the output of the sweep sound.

  The PWM converter 66 generates and outputs a PWM pulse having a duty ratio converted from the amplitude voltage data set in the register 60 and having the frequency set in the register 64 by the frequency setting unit 62.

  FIG. 4 is a graph showing conversion characteristics for converting the amplitude voltage data into the duty ratio in the PWM converter 66 of FIG. In FIG. 4, the horizontal axis is amplitude voltage data, for example, 8-bit data, which is all 1 and has a maximum value Dmax.

  The vertical axis represents the duty ratio R, the maximum value Dmax of the amplitude voltage data, the duty ratio R is 100%, the amplitude voltage data 0, the duty ratio R is 0%, and the intersection of 0 to 100% and Dmax is connected. A straight line is set as a conversion characteristic for converting the amplitude voltage data into the duty ratio R.

  Next, details of the amplitude voltage data 35 read out by the amplitude voltage data setting unit 58 when the sweep sound is output and set to obtain the duty ratio for the PWM conversion unit 66 via the register 60 will be described.

  FIG. 5 is a graph showing a sound pressure characteristic and an impedance characteristic with respect to the frequency of the speaker 46 used in the house alarm device of the present embodiment. In FIG. 5, the horizontal axis represents frequency, and the vertical axis represents sound pressure level and impedance Z. The frequency on the horizontal axis is a logarithmic axis.

  The speaker 46 according to the present embodiment outputs a sweep sound in addition to the speaker while changing the frequency of the drive voltage having a constant amplitude voltage in an audible frequency range, for example, a range of 150 Hz to 20 kHz. Can be obtained. Further, the impedance Z of the loudspeaker becomes a characteristic indicated by the impedance characteristic 72 with respect to the frequency change.

  The sound pressure characteristic 70 has a peak at a frequency fp1 near 750 Hz, and a higher peak at a frequency fp2 near 3.2 kHz. In contrast to such sound pressure peaks at the frequencies fp1 and fp2, the impedance characteristic 72 has a high impedance Z at the sound pressure peak portions at the frequencies fp1 and fp2, and the other sound pressures are low. The impedance Z is low in the frequency band.

  6 shows a case where a drive voltage having a constant amplitude voltage Vr is applied to the speaker 46 having the sound pressure characteristic 70 and the impedance characteristic 72 shown in FIG. 5 while changing the frequency in the sweep frequency range fs to fe to output a sweep sound. A driving voltage and a driving current are shown together with an impedance characteristic 72.

  FIG. 6A shows the same impedance characteristic 72 as shown in FIG. 5, and has peak portions where the impedance Z increases at two locations of the frequencies fp1 and fp2.

  FIG. 6B shows a drive voltage distribution 74 when a drive voltage (sine wave voltage) having an amplitude voltage Vr is applied to the speaker and the frequency is changed in the sweep frequency range from the start frequency fs to the end frequency fe. ing.

  When the sweep sound is output from the speaker with the drive voltage distribution 74 having the constant amplitude voltage Vr in such a sweep frequency range, the drive current of the speaker becomes the drive current distribution 76 shown in FIG. 6C. In the drive current distribution 76, the current value decreases in the portions of the impedances fp1 and fp2 where the impedance in the sweep frequency range becomes high, and a large current flows in other frequency bands with low impedance.

  Therefore, in the present invention, as shown in FIG. 6B, when a sweep sound is output from the speaker by changing the frequency in the sweep frequency range by the drive voltage having the constant amplitude voltage Vr as shown in FIG. 6B. The drive current Ir1 flowing through the speaker at a frequency fp1, for example, is obtained as a reference current with a high sound pressure and a high impedance Z in the drive current distribution 76 shown in FIG. This is set by the provided speaker reference current setting unit 54.

  FIG. 7 is a time chart showing an amplitude voltage distribution for keeping the speaker drive current at the reference current Ir obtained from FIG. 6 when the frequency is changed in the range of the sweep frequency when the sweep sound is output. 7A shows the same impedance characteristic 72 as shown in FIG. 5, and the amplitude voltage in the sweep frequency range for keeping the speaker drive current at the reference current Ir as shown in FIG. 7B in FIG. 7B. A distribution 78 is shown. The amplitude voltage distribution 78 in FIG. 7B can be obtained as follows.

  First, the product (Vr × Ir) of the amplitude voltage Vr and the reference current Ir at the frequency fp1 having the highest sound pressure and the highest impedance shown in FIGS. 6B and 6C is obtained.

  As shown in FIG. 7C, the voltage distribution characteristic 78 for obtaining the drive current distribution 80 that coincides with the reference current Ir in the entire sweep frequency range has the above-mentioned product (Vr × Ir) as shown in FIG. The amplitude voltage may be obtained by dividing by the current value of the drive current distribution 76 shown in FIG.

  The amplitude voltage distribution 78 of FIG. 7B obtained in this way is a characteristic in which the amplitude voltage becomes Vr at the frequency fp1 at which the reference current Ir is obtained, and the amplitude voltage is lowered in other frequency bands with low impedance. It has become.

  In the characteristics of the speaker in FIG. 5, there is a frequency fp2 with high sound pressure and high impedance near 3.2 kHz. In this part, the amplitude voltage does not reach Vr, but at a peak. An increased amplitude voltage is shown.

  As shown in FIG. 7B, when the amplitude voltage data distribution 78 that keeps the drive current at the reference current Ir in the sweep frequency range is obtained, the amplitude value is sampled in a predetermined frequency unit and converted into digital data, for example, 8-bit data. By conversion, amplitude voltage data 35 as shown in FIG. 8 can be generated.

  The amplitude voltage data 35 of FIG. 8 discretizes the frequency into frequencies f1 to fn per sweep frequency range, and the voltage values according to the amplitude voltage distribution 78 of FIG. 7B at the respective frequencies are converted into the amplitude voltage data V1 to Vn. The amplitude voltage data 35 is stored in advance in the EEPROM 32 shown in FIG.

  FIG. 9 is a flowchart showing the generation processing of the amplitude voltage data of FIG. 8, and the sound pressure measuring device for measuring the sound pressure output from the speaker of the residential alarm device 10 of this embodiment shown in FIG. The creation process is performed using a measuring instrument that measures the driving voltage and driving current of the applied driving signal, and a measurement test device such as a personal computer for data processing. Sound pressure is measured using an acoustic room.

  In the amplitude data creation process, first, a sweep condition is set for the residential alarm 10 of the present embodiment prepared as a measurement target in step S1. As shown in FIG. 6B, this sweep condition is performed by changing the frequency in the sweep frequency range from the start frequency fs to the end frequency fe with the amplitude voltage Vr for obtaining the sound pressure level required for the alarm device. Set the conditions for sound output.

  Specifically, amplitude voltage data corresponding to the amplitude voltage Vr is fixedly set from the amplitude data setting unit 58 to the register 60 provided in the CPU 24 of FIG. Subsequently, in step S2, a frequency that changes linearly with the passage of time in the sweep frequency range from the frequency setting unit 66 is sequentially set in the register 64, whereby the PWM conversion unit 66 has a constant duty ratio and in the sweep frequency range. A PWM pulse whose frequency changes is output, a component equal to or higher than the upper limit frequency of the audio frequency band is cut by the low-pass filter 42, converted into a sine wave waveform, amplified by the amplifier 66, and then a sweep sound is output from the speaker 46.

  Subsequently, in step S3, the speaker driving current in the sweep frequency range is measured, and this measurement gives a driving current distribution 76 as shown in FIG. 6C. Therefore, in step S4, the peak sound pressure measured at the same time is measured. Is detected as a speaker reference current Ir in step S5.

  Subsequently, as shown in FIG. 7, the product (Vr × Ir) of the reference voltage Vr and the reference current Ir is divided by the drive current distribution 76 of FIG. 6C to obtain the voltage amplitude distribution 78 of FIG. 8 is created and discretized into predetermined frequency units to generate amplitude voltage data 35 as shown in FIG. 8, and this is stored in the EEPROM 32 as shown in FIG.

  In the process of FIG. 9, the sweep current is output to the speaker by using the residence guard 10 of the present embodiment to be measured, and the reference current Ir and the drive current distribution are measured. When the sound pressure characteristic 70 and the impedance characteristic 72 are obtained for the speaker used in advance, the sound pressure characteristic 70 and the impedance characteristic 72 are used to generate a frequency with a high sound pressure and a high impedance. When fp1 is determined and the impedance characteristic 72 is determined, the drive current distribution 76 of FIG. 6C when the constant amplitude voltage Vr shown in FIG. 6 is added can also be calculated. The amplitude voltage data 78 of FIG. 8 may be created by obtaining the amplitude voltage distribution 78 of 7 (B).

  Furthermore, even if the sound pressure characteristic 70 of the speaker is unknown, if the driving current distribution 76 as shown in FIG. 6C can be measured by driving the speaker in the sweep frequency range, based on the driving current distribution 76, For the sweep frequency range shown in FIG. 7B, the amplitude voltage distribution 78 for maintaining the speaker drive current at the reference current Ir can be obtained in the same manner.

  FIG. 10 is a flowchart showing a sweep sound output process according to the embodiment of the PWM processing unit of FIG. In FIG. 10, first, after setting the read mode of the amplitude voltage data 35 from the EEPROM 32 in step S11, a frequency sweep for increasing the frequency f by a predetermined frequency Δf is started in step S12.

  In step S13, the amplitude voltage data corresponding to the current frequency f is read from the EEPROM 32 and stored in the register 60. In step S14, the amplitude voltage data is converted into a duty ratio according to the conversion characteristics shown in FIG. At this time, since the current frequency f at which the sweep obtained in step S12 is started is set in the register 64 by the frequency setting unit 62, the PWM converter 66 has the duty ratio obtained in step S14, and the register 64 The PWM pulse of the frequency set to is output.

  A PWM pulse having a duty ratio corresponding to the amplitude voltage data 35 of the EEPROM 32 in steps S12 to S15 and having a frequency that increases linearly in the sweep frequency range is output. The upper limit frequency component is cut, converted into a sine wave waveform, amplified by the amplifier 44, and then a sweep sound is output from the speaker 46.

  At this time, the drive current flowing through the speaker 46 has a smaller amplitude voltage in a frequency band with a low impedance than the reference voltage Vr of the frequency fp1 where the speaker drive voltage has a high impedance and a high sound pressure as shown in FIG. As a result, as shown in FIG. 7C, the output of the sweep sound in which the speaker drive current is held at the reference current Ir in the sweep frequency range can be realized.

  FIG. 11 is a block diagram showing another embodiment of the PWM processing unit shown in FIG. 2. In this embodiment, the amplitude voltage data is not stored in the ROM, but the amplitude reference data is approximated, so that the classification is performed. Amplitude voltage data is set as a function by executing a program, and control is performed so that the speaker drive current is kept near the reference current in the sweep frequency range.

  In FIG. 11, the sweep sound processing unit 56 provided in the CPU 24 includes an amplitude voltage data setting unit 82, a register 60, a frequency setting unit 62, a register 64, a PWM conversion unit 66, and a control unit 68. 3, the amplitude voltage data is set in the PWM conversion unit 66 by the amplitude voltage data setting unit 58 based on the amplitude voltage data 35 of the EEPROM 32 in FIG. The embodiment is characterized in that the amplitude voltage data is approximately set in the PWM processing unit 56 based on the piece function by the amplitude voltage data setting unit 82.

  FIG. 12 is a time chart showing an approximate amplitude voltage distribution for maintaining the speaker drive current at the reference current in the embodiment of FIG. 12A shows the same impedance characteristic 72 as shown in FIG. 5, and FIG. 12B shows the amplitude for maintaining the speaker drive current at the reference current Ir in the same sweep frequency range as shown in FIG. 7B. The voltage distribution 78 is indicated by an imaginary line.

  In the embodiment of FIG. 11, the amplitude voltage distribution 78 is not used as it is, but an approximate amplitude voltage distribution 84 obtained by approximating it is used. The approximate amplitude voltage distribution 84 approximates the peak portion of the amplitude voltage at the frequencies fp1 and fp2 with a rectangular pattern.

  Such an approximate amplitude voltage distribution 84 can be defined as a piecewise function for a frequency interval as shown in FIG. That is, V = V1, V2, V1, V3, and V1 are set as the division functions for the five frequency sections f1 to f2, f2 to f3, f3 to f4, f4 to f5, and f5 to f6, respectively.

  By sequentially setting the piece function as shown in FIG. 13 based on the frequency change at the time of sweep sound output, the approximate amplitude voltage distribution 84 that changes in a rectangular shape shown in FIG. As a result, a drive current distribution 86 as shown in FIG. 12C can be obtained. The drive current distribution 86 can be controlled so that the drive current falls within a predetermined error range with respect to the reference current Ir at the frequency fp1.

  FIG. 14 shows another example of the approximate amplitude voltage distribution used in the embodiment of FIG. In this example, as shown in FIG. 14B, the peak amplitude voltage portions of the frequencies fp1 and fp2 at which the sound pressure and the impedance are increased are approximated by a polygonal line with respect to the rectangular approximation of FIG. The error of the speaker drive current with respect to the reference current Ir is further reduced by reducing the deviation from the original amplitude voltage distribution 78 and obtaining the drive current distribution 90 shown in FIG.

  FIG. 15 shows a list of division functions for each frequency division in the sweep frequency range created from the approximate amplitude voltage distribution 88 of FIG. 14B. That is, the sweep frequency range of FIG. 14 is divided into seven frequency sections shown in the frequency section, and the value of the amplitude voltage V in each section is expressed by a linear equation having a constant or positive / negative slope.

  FIG. 16 is a flowchart showing an amplitude data creation process for obtaining a piecewise function of the sweep frequency range of FIGS. 13 and 15. 16, steps S21 to S26 are the same as steps S1 to S6 of FIG. 9, and a drive voltage distribution 78 shown in FIG. 7B is obtained based on the drive current distribution 76 shown in FIG. 6C. Yes.

  Subsequently, in step S27, as shown in FIG. 12B or FIG. 14B, the amplitude voltage data distribution is approximated, and based on the approximated amplitude voltage data distribution, classification as shown in FIG. 13 in step S27. The function or the division function as shown in FIG. 15 is determined and described as a parameter in a program for realizing the function of the PWM processing unit 56 provided in the CPU 24.

  FIG. 17 is a flowchart showing a sweep sound output process by the PWM processing unit of FIG. In FIG. 17, in step S31, the constants of the piecewise function for sweep output as shown in FIG. 13 or FIG. 15 are set. The constants in the piecewise function of FIG. 13 are V1, V2, and V3. The constants in the piecewise function of FIG. 15 are V1, V2, V3, and slopes a, -b, c, -d.

  Next, in step S32, a frequency sweep for increasing the current frequency f by a predetermined frequency Δf is started. Subsequently, in step S33, a classification function of the classification to which the current frequency f belongs is selected. Subsequently, in step S34, drive voltage data is calculated from the selected piece function and stored in the register 60. In step S35, the drive voltage data is converted into a duty ratio in accordance with the conversion characteristics shown in FIG.

  In step S36, a PWM pulse having the frequency set in the register 64 by the frequency setting unit 62 and having the duty ratio converted in step S35 is output. Such processes of steps S32 to S36 are repeated until the sweep end frequency is reached in step S37.

  In the above embodiment, the case where the sweep sound is output by the PWM process is taken as an example, but the present invention can be applied to the output of the sweep sound other than the PWM process.

  For example, the variable frequency oscillator may be changed in the sweep frequency range under the control of the CPU 24, and the speaker may be driven by amplifying the frequency signal from the variable frequency oscillator with an amplifier.

  Also in such a case, the current when the speaker is driven with a constant amplitude Vr at a frequency fp where the sound pressure of the speaker is high and the impedance is high is obtained as a reference current Ir. For example, as shown in FIG. For example, by controlling the gain of the amplifier so as to variably control the amplitude level of the frequency signal output from the waveform in accordance with the amplitude voltage distribution 78 in the sweep frequency range, the speaker drive current in the sweep frequency range as shown in FIG. Can be driven to keep the current at the reference current Ir.

  In addition, the above embodiment is an example of a residential alarm for fire detection, but other appropriate abnormalities such as a gas leak alarm and a security alarm are detected. The present embodiment can be applied to the alarm device as it is. Moreover, the present invention can be applied not only to residential use but also to alarm devices for various uses such as buildings and offices.

  Moreover, although said embodiment took the case where the sensor part was integrally provided in the alarm device as an example, as another embodiment, the alarm device which provided the sensor part separately from the alarm device may be sufficient. .

The present invention is not limited to the above-described embodiments, includes appropriate modifications that do not impair the objects and advantages thereof, and is not limited by the numerical values shown in the above-described embodiments.

Explanatory drawing which showed the external appearance of the house alarm device by this invention The block diagram which showed embodiment of the residence guard by this invention The block diagram which showed embodiment of the PWM process part of FIG. The graph which showed the conversion characteristic which converts into the duty ratio from the audio | voice data in FIG. Graph showing the sound pressure and impedance characteristics with respect to speaker frequency Time chart showing drive voltage and drive current when a sweep signal of constant amplitude voltage is applied to the speaker Time chart showing the amplitude voltage distribution that keeps the drive current at the reference current Explanatory drawing which showed the amplitude voltage data created from the amplitude voltage distribution of FIG.7 (B) The flowchart which showed the creation process of the amplitude voltage data of FIG. The flowchart which showed the sweep sound output process by the PWM process part of FIG. The block diagram which showed other embodiment of the PWM process part of FIG. Time chart showing approximate amplitude voltage distribution that keeps drive current at reference current Explanatory diagram showing a piecewise function created from the approximate amplitude voltage distribution of FIG. Time chart showing another approximate amplitude voltage distribution that keeps the drive current at the reference current Explanatory diagram showing a piecewise function created from the approximate amplitude voltage distribution of FIG. FIG. 13 and FIG. 15 are flowcharts showing the amplitude voltage data creation process. The flowchart which showed the sweep sound output process by the PWM process part of FIG.

Explanation of symbols

10: House alarm 12: Cover 14: Body 15: Mounting hook 16: Smoke detector 18: Sound hole 20: Alarm stop switch 22: LED
24: CPU
26: Sensor unit 28: Notification unit 30: Operation unit 32: ROM
34: RAM
36: Transfer unit 40: Battery power source 42: Low pass filter 44: Amplifier 46: Speaker 48: Display circuit unit 50: Abnormality monitoring unit 52: Sweep sound processing unit 54: Speaker reference current setting unit 56: PWM processing unit 58: Audio Data setting unit 60, 66: Register 62: PWM processing unit 64: Frequency setting unit 68: Control unit 70: Sound pressure characteristic 72: Impedance characteristic

Claims (7)

When an abnormality is detected, an alarm device that outputs a sweep sound whose frequency changes within a predetermined range as time passes from the speaker as an alarm sound,
A reference current setting unit that sets, as a reference current, a drive current that flows when a drive voltage of a predetermined amplitude having a predetermined frequency with high sound pressure and high impedance in the speaker is applied;
A PWM processing unit that outputs a PWM pulse train in which a duty ratio is set so as to keep the driving current of the speaker near the reference current;
An acoustic output circuit unit that amplifies the PWM pulse train after passing through a low-pass filter and converting it into an audio signal, and outputting it from a speaker;
An alarm device characterized by providing.
The alarm device according to claim 1, wherein the PWM processing unit includes:
An amplitude voltage data setting unit for setting amplitude voltage data of the speaker that keeps the driving current of the speaker near the reference current with respect to a change in frequency;
A frequency setting unit for setting a frequency that linearly changes in a predetermined frequency range over time;
A PWM converter having a duty ratio converted from the amplitude voltage data of the amplitude voltage data setting unit, and generating and outputting a PWM pulse having a linearly changing frequency set by the frequency setting unit;
An alarm device comprising:
The alarm device according to claim 2, wherein the amplitude voltage data setting unit includes:
A product of the reference current and a predetermined amplitude voltage is divided by a drive current distribution when a sweep sound is output from the speaker by adding the predetermined amplitude voltage over the frequency range to obtain an amplitude voltage data distribution over the frequency range. When a sweep sound is output, a PWM pulse having a duty ratio according to the amplitude voltage data distribution is output to the PWM conversion unit according to a frequency change, and the driving current of the speaker is held at the reference current. Alarm device characterized by.
The alarm device according to claim 2, wherein the amplitude voltage data setting unit includes:
The amplitude voltage distribution over the frequency range obtained by dividing the product of the reference current and the predetermined amplitude voltage by the drive current distribution when the predetermined amplitude voltage is added over the frequency range and a sweep sound is output from the speaker. When the sweep sound is output, a PWM pulse having a duty ratio according to the amplitude voltage calculated by the piece function according to the frequency change is output to the PWM converter, and the driving current of the speaker is calculated. An alarm device characterized by being held near the reference current.
When an abnormality is detected, an alarm device that outputs a sweep sound whose frequency changes within a predetermined range as time passes from the speaker as an alarm sound,
A reference current setting unit that sets, as a reference current, a drive current that flows when a drive voltage of a predetermined amplitude having a predetermined frequency with high sound pressure and high impedance of the speaker is applied;
A sweep sound output processing unit for controlling an amplitude voltage applied to the speaker so as to keep a speaker drive current associated with a frequency change in the vicinity of the reference current when the sweep sound is output;
An alarm device characterized by providing.
The alarm device according to claim 5, wherein the sweep sound output processing unit is
The amplitude voltage distribution over the frequency range obtained by dividing the product of the reference current and the predetermined amplitude voltage by the drive current distribution when the predetermined amplitude voltage is added over the frequency range and a sweep sound is output from the speaker. And an amplitude voltage in accordance with the amplitude voltage distribution is applied to the speaker in accordance with a change in frequency when a sweep sound is output, thereby holding the speaker drive current at the reference current.
The alarm device according to claim 6, wherein the sweep sound output processing unit includes:
The amplitude voltage distribution over the frequency range obtained by dividing the product of the reference current and the predetermined amplitude voltage by the drive current distribution when the predetermined amplitude voltage is added over the frequency range and a sweep sound is output from the speaker. And a speaker driving current is held in the vicinity of the reference current by applying an amplitude voltage calculated by the piece function according to a frequency change to the speaker when a sweep sound is output. Alarm to do.

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