JP5865029B2 - Alarm - Google Patents

Description

  The present invention relates to an alarm device.

  Conventionally, when an abnormal state such as a gas leak or a fire is detected, an alarm device has been proposed that outputs an alarm sound from a buzzer to notify the abnormal state. In this alarm device, it is important to diagnose whether or not a failure has occurred in the alarm sound notification function. In such an alarm device, for example, an alarm sound is output by a piezoelectric buzzer or a speaker. In particular, in the piezoelectric buzzer, Sn whisker which is a needle-like product extends from a metal plate terminal, and a short circuit failure occurs due to contact with the piezoelectric element electrode, which may cause an abnormal alarm sound.

  Therefore, an alarm device has been proposed that emits an alarm sound in a non-audible frequency range when an abnormal state such as gas leakage or fire does not occur. According to this alarm device, an alarm sound when no abnormal state occurs is not audible to humans, so that the speaker can be diagnosed without the alarm sound becoming noise (see, for example, Patent Document 1). .

JP-A-7-129875

  However, the alarm is generally battery powered. For this reason, for example, when trying to determine a failure of the buzzer based on a decrease in the voltage applied to the buzzer, a short circuit failure has occurred in the buzzer, or the applied voltage has decreased, or the battery voltage has decreased and the applied voltage has decreased. May not be able to be determined, and it may be determined that a buzzer failure occurs despite a decrease in battery voltage.

  The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide an alarm device capable of improving the accuracy of a failure diagnosis of a buzzer. is there.

The alarm device of the present invention is an alarm device that outputs an alarm sound from a piezoelectric buzzer when an abnormal state is detected, and notifies the abnormal state, and has an opposite phase to one terminal and the other terminal of the piezoelectric buzzer. Switch means for applying a high level signal and a low level signal to output an alarm sound, and by operation of the switch means, a high level signal and a low level signal having opposite phases to one terminal and the other terminal of the piezoelectric buzzer When the voltage applied to one terminal of the piezoelectric buzzer is lower than the threshold when the voltage is applied, failure diagnosis means for judging that the piezoelectric buzzer is short-circuited , and lowering the threshold according to the decrease in battery voltage comprising a threshold value setting means, and switching means, serves as a switch function for applying a voltage for outputting an alarm sound, and a switching function for applying a voltage for diagnosing short-circuit failure It is characterized in.

  According to this alarm device, since the threshold value is lowered in accordance with the decrease in the battery voltage, the applied voltage to the buzzer is reduced and a short circuit occurs when the battery voltage is lowered as in the case where the threshold value is fixed. It is possible to prevent a situation in which an erroneous determination such as being present is made. Therefore, it is possible to improve the accuracy of the buzzer failure diagnosis.

In the alarm device of the present invention, it is preferable that the threshold setting means sets the threshold based on information on the battery voltage immediately before the failure diagnosis means diagnoses a short circuit failure of the piezoelectric buzzer.

  According to this alarm device, since the threshold value is set based on the battery voltage information immediately before diagnosing the buzzer failure, the threshold value is not set based on the past battery voltage. The accuracy can be further improved.

  According to the present invention, it is possible to provide an alarm device capable of improving the accuracy of buzzer failure diagnosis.

It is a block diagram which shows the alarm device which concerns on embodiment of this invention. It is a circuit diagram which shows an example of the buzzer drive circuit, buzzer, and battery voltage input circuit which were shown in FIG. It is a flowchart which shows the buzzer failure diagnosis of the alarm device which concerns on this embodiment.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings. FIG. 1 is a configuration diagram illustrating an alarm device according to an embodiment of the present invention. As shown in FIG. 1, the alarm device 1 includes a gas sensor 10, a CPU (Central Processing Unit) 20, a buzzer driving circuit 30, a buzzer 40, and a battery voltage input circuit 50, and gas leakage (abnormal state). Is detected, an alarm sound is output from the buzzer 40 to notify the abnormal state. Such an alarm device 1 is installed in a home or the like, for example, and notifies a user at home of a gas leak.

  The gas sensor 10 outputs a signal corresponding to the concentration to the CPU 20 when there is a gas to be detected around. Specifically, various sensors such as a semiconductor sensor, a catalytic combustion sensor, and an electrochemical sensor are used as the gas sensor 10.

  The CPU 20 controls the entire alarm device 1. When the gas sensor 10 detects a detection target gas having a predetermined concentration or more, the CPU 20 determines that a gas leak has occurred. The CPU 20 includes a buzzer control unit 21. When the buzzer control unit 21 determines that a gas leak has occurred, the buzzer control unit 21 transmits a signal to that effect to the buzzer drive circuit 30.

  The buzzer drive circuit 30 drives the buzzer 40 to generate sound. For example, a drive signal of 4 kHz (resonance point of the buzzer 40) is input from the buzzer control unit 21, and the buzzer drive circuit 30 outputs an alarm sound from the buzzer 40 according to the drive signal.

  Further, the CPU 20 includes a failure diagnosis unit (failure diagnosis unit) 22 and a threshold setting unit (threshold setting unit) 23. The failure diagnosis unit 22 determines a failure of the buzzer 40 based on the voltage applied to the buzzer 40. Specifically, the failure diagnosis unit 22 determines that the buzzer 40 is in failure when the applied voltage is equal to or less than a threshold value. Moreover, the threshold value setting part 23 sets a threshold value according to a battery voltage, and reduces a threshold value according to the fall of a battery voltage.

  The battery voltage input circuit 50 transmits battery voltage information to the CPU 20. For this reason, the threshold setting unit 23 sets the threshold based on the battery voltage information input through the battery voltage input circuit 50.

  FIG. 2 is a circuit diagram showing an example of the buzzer driving circuit 30, the buzzer 40, and the battery voltage input circuit 50 shown in FIG. In FIG. 2, the CPU 20 is also illustrated for convenience of explanation.

  As shown in FIG. 2, the buzzer drive circuit 30 is composed of six resistors R31 to R36 and two npn transistors Q31 and Q32.

  More specifically, the first signal line 31 extends from the buzzer control unit 21, and a drive signal is input to the first resistor R 31 via the first signal line 31. The other end of the first resistor R31 is connected to the base of the first npn transistor Q31 and to one end of the second resistor R32. The emitter of the first npn transistor Q31 and the other end of the second resistor R32 are grounded.

  Similarly, the second signal line 32 extends from the buzzer control unit 21, and a drive signal is input to the third resistor R <b> 33 via the second signal line 32. The other end of the third resistor is connected to the base of the second npn transistor Q32 and to one end of the fourth resistor R34. The emitter of the second npn transistor Q32 and the other end of the fourth resistor R34 are grounded.

  The collector of the first npn transistor Q31 is connected to one end of the fifth resistor R35. The other end of the fifth resistor R35 is connected to a power supply unit (battery). Similarly, the collector of the second npn transistor Q32 is connected to one end of the sixth resistor R36. The other end of the sixth resistor R36 is connected to a power supply unit (battery).

  Here, if the connection point between the collector of the first npn transistor Q31 and the fifth resistor R35 is A and the connection point between the collector of the second npn transistor Q32 and the sixth resistor R36 is B, the buzzer 40 is connected to the connection point A. Connected to point B.

  The failure diagnosis unit 22 reads the voltage at the connection point B and diagnoses the failure of the buzzer 40. The first to fourth resistors R31 to R34 and the two npn transistors Q31 and Q32 of the buzzer driving circuit 30 are preferably formed as a chip.

  The battery voltage input circuit 50 includes first and second resistors R51 and R52. One end of the first resistor R51 is connected to the power supply unit (battery), and the other end is connected to one end of the second resistor R52. The other end of the second resistor R52 is grounded.

  The threshold setting unit 23 acquires battery voltage information by reading the voltage value at the connection point C between the other end of the first resistor R51 and one end of the second resistor R52.

  Next, the outline of the alarm sound output according to the present embodiment will be described. First, the buzzer control unit 21 outputs a drive signal via the first signal line 31 and the second signal line 32. At this time, the buzzer control unit 21 outputs a pulse signal (frequency 4 kHz) of 250 μs. The high and low timings of the drive signal from the first signal line 31 and the drive signal from the second signal line 32 are in opposite phases.

  Here, it is assumed that the buzzer 40 is normal, the drive signal from the first signal line 31 is H level, and the drive signal from the second signal line 32 is L level. In this case, the first npn transistor Q31 is turned on and the second npn transistor Q32 is turned off. Then, the connection point A becomes L level and the connection point B becomes H level, and a voltage is applied to the buzzer 40.

  On the other hand, it is assumed that the drive signal from the first signal line 31 is L level and the drive signal from the second signal line 32 is H level. In this case, the first npn transistor Q31 is turned off and the second npn transistor Q32 is turned on. Then, the connection point A becomes H level and the connection point B becomes L level, and a voltage is applied to the buzzer 40.

  The alarm device 1 outputs an alarm sound from the buzzer 40 by repeating the above operation.

  Next, the buzzer failure diagnosis of the alarm device 1 according to the present embodiment will be described with reference to a flowchart. FIG. 3 is a flowchart showing a buzzer failure diagnosis of the alarm device 1 according to the present embodiment.

  First, the threshold setting unit 23 reads the voltage value at the connection point C (S1). At this time, the threshold setting unit 23 reads the voltage at the connection point C by inputting the voltage at the connection point C after A / D conversion. Next, the failure diagnosis unit 22 determines the applied voltage from the voltage value at the connection point B (S2). Also at this time, the failure diagnosis unit 22 determines the voltage applied to the buzzer 40 by inputting the voltage at the connection point B after A / D conversion.

  Thereafter, the threshold setting unit 23 calculates and sets a threshold used for failure diagnosis of the buzzer 40 from the voltage value at the connection point C (S3). At this time, the threshold value setting unit 23 decreases the threshold value as the voltage value at the connection point C decreases. Next, the failure diagnosis unit 22 determines whether or not the voltage applied to the buzzer 40 is equal to or less than the threshold set by the threshold setting unit 23 (S4).

  When it is determined that the applied voltage of the buzzer 40 is equal to or lower than the threshold set by the threshold setting unit 23 (S4: YES), the applied voltage to the buzzer 40 is reduced beyond the normal range with respect to the battery voltage. Can be judged. For this reason, the failure diagnosis unit 22 determines that a failure such as a short circuit has occurred in the buzzer 40 (S5). Then, the process shown in FIG. 3 ends. At this time, the alarm device 1 may display a failure of the buzzer 40 from an LED (Light Emitting Diode) (not shown) or the like.

  On the other hand, when it is determined that the applied voltage of the buzzer 40 is not less than or equal to the threshold set by the threshold setting unit 23 (S4: YES), it can be determined that the applied voltage to the buzzer 40 is within a normal range with respect to the battery voltage. . For this reason, the failure diagnosis unit 22 determines that a failure such as a short circuit has not occurred in the buzzer 40 (S6). Then, the process shown in FIG. 3 ends.

  As described above, according to the alarm device 1 and the buzzer failure diagnosis method according to the present embodiment, the threshold voltage is decreased according to the decrease in the battery voltage, so that the battery voltage is decreased as in the case where the threshold is fixed. At this time, it is possible to prevent a situation in which an erroneous determination is made such that a voltage applied to the buzzer 40 decreases and a short circuit occurs. Therefore, it is possible to improve the accuracy of the failure diagnosis of the buzzer 40.

  Further, since the threshold value is set based on the battery voltage information immediately before diagnosing the failure of the buzzer 40 (that is, before the failure diagnosis of the buzzer 40 (S4) in the series of processes), the threshold value is set based on the past old battery voltage. Without being set, the accuracy of the failure diagnosis of the buzzer 40 can be further improved.

  As described above, the present invention has been described based on the embodiment, but the present invention is not limited to the above embodiment, and may be modified without departing from the gist of the present invention. For example, in the said embodiment, not only the circuit structure shown in FIG. 2 but another circuit structure may be sufficient.

  Moreover, although the said embodiment demonstrated the gas alarm device, it is not restricted to this, You may apply to a fire alarm device and a gas fire alarm device, and if it is battery drive, it is applied to other alarm devices. Also good.

  In the present embodiment, the threshold setting and the buzzer 40 failure diagnosis are performed in a series of flows. However, the threshold setting and the buzzer 40 failure diagnosis are performed in parallel, for example. It may be executed in a separate flow. In this case, only the threshold setting process may be executed every predetermined time.

  Further, in the present embodiment, when the applied voltage is equal to or lower than the threshold value, it is determined that the buzzer 40 is faulty. However, this process is repeated a plurality of times, and when the applied voltage is equal to or lower than the predetermined number of times, the buzzer 40 is determined. It may be determined that there is a failure.

  Further, in the above description, the applied voltage is a concept that includes not only a voltage applied when an alarm sound is actually output from the buzzer 40 but also a voltage in a standby state. For example, as shown in FIG. 2, when the drive signal is not output from the buzzer control unit 21 (that is, both the first and second drive signals are at the L level), the connection point B becomes the H level, and this voltage is set as the applied voltage. It is a concept that includes doing.

1 ... alarm 10 ... gas sensor 20 ... CPU
21 ... Buzzer control unit 22 ... Failure diagnosis unit (failure diagnosis means)
23: Threshold setting unit (threshold setting means)
30 ... Buzzer drive circuit 40 ... Buzzer 50 ... Battery voltage input circuit R31-R36, R51, R52 ... Resistors Q31, Q32 ... npn transistor

Claims (2)

An alarm device that outputs an alarm sound from a piezoelectric buzzer when an abnormal state is detected and notifies the abnormal state,
Switch means for outputting a warning sound by applying a high level signal and a low level signal having opposite phases to one terminal and the other terminal of the piezoelectric buzzer;
Applied voltage to one terminal of the piezoelectric buzzer when a high level signal and a low level signal having opposite phases are applied to one terminal and the other terminal of the piezoelectric buzzer by the operation of the switch means Fault diagnosis means for determining that the piezoelectric buzzer is a short-circuit fault when
Threshold setting means for reducing the threshold in accordance with a decrease in battery voltage ,
The switch means has both a switch function for applying a voltage for outputting an alarm sound and a switch function for applying a voltage for diagnosing a short-circuit failure . 2. The alarm device according to claim 1, wherein the threshold setting unit sets the threshold based on battery voltage information immediately before the failure diagnosis unit diagnoses a short-circuit failure of the piezoelectric buzzer.

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