JP7488133B2 - Alarm - Google Patents

Description

The present invention relates to an alarm.

When an alarm that runs on a 24V direct current (DC) power supply is in a transitional state when the power supply voltage is low (e.g. 17V) upon power-on, a greater current consumption is required to activate the alarm than when the power supply voltage is stable at 24V. For example, when a DC 24V power supply voltage is supplied to an alarm that consumes 1.5W, if the alarm starts to operate after the power supply voltage reaches 24V, the current consumption will be approximately 63mA. On the other hand, if the alarm starts to operate when the power supply voltage is, for example, 10V during the process before the power supply voltage reaches 24V, a current of approximately 150mA will flow through the alarm immediately after that.

The above phenomenon has the following impact on alarm installers. For example, if a single power source is to be used to power 10 alarms, each of which has a power consumption of 1.5W listed on the alarm body, the installer will prepare a 24V power source equivalent to 15W (=24V x 63mA x 10). If 10 alarms are connected to this 24V power source and the power is turned on all at once, as the power supply voltage rises, if all 10 alarms start up simultaneously at, for example, 10V, a current of 150mA x 10 units = 1.5A will flow instantaneously. A current of 1.5A exceeds the supply capacity of the 15W equivalent power supply prepared by the installer, and so the power supply will be shut off or a current limit will be applied, resulting in malfunctions such as the alarms not starting up and unstable startup operations.

The alarm in Patent Document 1 has been proposed as a technology for dealing with the large current that flows when the power is turned on. The alarm in Patent Document 1 comprises a DCDC converter that converts the power supply voltage to a predetermined voltage and supplies it to a gas sensor, and a control means that controls the DCDC converter. The control means starts voltage conversion by the DCDC converter with a delay from the start of the control means by turning on the power supply voltage, thereby starting voltage conversion after the power supply voltage has risen sufficiently, preventing a large current from flowing.

JP 2015-219554 A

However, in the alarm of Patent Document 1, voltage conversion does not begin and the gas sensor is not activated until the power supply voltage has risen sufficiently, so it may take some time for the alarm to reach a state where it can perform its alarm function after the power is turned on.

The present invention was made in consideration of the above-mentioned circumstances, and its purpose is to provide an alarm that can keep the startup current low and quickly achieve stable startup operation in the transient state when the power supply voltage is turned on.

In order to achieve the above-mentioned object, an alarm device according to the present invention is characterized by the following (1) to (6).
(1) a first sensor for detecting a first gas;
a second sensor that detects a second gas different from the first gas and consumes a larger current than the first sensor;
a control unit that drives the first sensor and the second sensor,
When the control unit receives a supply of power supply voltage and starts operating, it starts driving the first sensor, and starts driving the second sensor with a delay from the point in time when the control unit started driving the first sensor.
(2) The alarm device described in (1) above, wherein the control unit starts driving the first sensor when the power supply voltage is a first voltage value, and starts driving the second sensor when the power supply voltage is a second voltage value higher than the first voltage value.
(3) The alarm device according to (2) above, wherein the second voltage value is a voltage value when the power supply voltage is stable.
(4) The alarm device according to any one of (1) to (3) above, wherein the control unit starts driving the second sensor after stopping driving of the first sensor.
(5) The alarm device described in any one of (1) to (4) above, wherein the control unit drives the first sensor to perform a fault diagnosis of the first sensor, and starts driving the second sensor after a time required for the fault diagnosis has elapsed.
(6) The first sensor and the second sensor are each formed of a single sensor,
The alarm device described in any one of (1) to (4) above, wherein the single sensor detects the first gas when a third voltage is applied thereto, and detects the second gas when a fourth voltage higher than the third voltage is applied thereto.

According to the alarm device configured as in (1) above, after the power supply is started, during the transitional period until the power supply voltage reaches a predetermined value and stabilizes, operation begins with the first sensor, which consumes a small amount of current, and then driving of the second sensor, which consumes a large amount of current, begins. This control makes it possible to start the alarm with the minimum current at which the alarm can operate during the transitional period when the power supply is started, thereby keeping the startup current small. This makes it possible to achieve stable startup operation without requiring a power supply with a capacity larger than necessary. Furthermore, according to the alarm device configured as in (1) above, when the control unit starts operating, driving of the first sensor begins immediately without waiting until the power supply voltage has risen sufficiently, so the alarm device can be started quickly. Therefore, the alarm function can be exerted sooner than in the case where sensor driving is not started until the power supply voltage has risen sufficiently after the control unit has started operating.

According to the alarm device having the configuration of (2) above, the second sensor starts to be driven after the power supply voltage has risen to the second voltage value, so that the second sensor can be driven with a current that is less than the current required to drive the second sensor when the power supply voltage is the first voltage value, which is lower than the second voltage value.

According to the alarm device configured as described above in (3), the current flowing through the second sensor can be reduced to a minimum by starting to operate the second sensor when the power supply voltage is stable.

According to the alarm device having the configuration of (4) above, by driving the second sensor after stopping the driving of the first sensor, it is possible to reduce current consumption compared to driving the first and second sensors simultaneously.

According to the alarm device configured as in (5) above, by starting the operation of the second sensor after the fault diagnosis of the first sensor is completed, the fault diagnosis of the first sensor can be performed with a minimum current.

According to the alarm device having the configuration of (6) above, even when a single sensor is used to detect the first and second gases, the first sensor, which operates at a lower voltage, i.e., consumes less current, is first driven, and then the second sensor is driven. This configuration makes it possible to reduce current consumption at startup.

According to the present invention, in the transient state when the power supply voltage is turned on, the startup current can be kept small and stable startup operation can be quickly achieved.

The present invention has been briefly described above. The details of the present invention will become clearer by reading the following description of the embodiment of the invention (hereinafter referred to as "embodiment") with reference to the attached drawings.

FIG. 1 is a functional block diagram showing an example of the schematic configuration of an alarm device according to one embodiment of the present invention. FIG. 2 is a front view showing an example of the appearance of the alarm device of FIG. FIG. 3 is a time chart showing an example of the operation of the alarm device of FIG. 1 from when power is turned on to when the initial inspection is completed. FIG. 4 is a graph showing an example of changes in power supply voltage and current consumption in the alarm device of FIG. 1 from when the power is turned on until the completion of the initial inspection. FIG. 5 is a diagram for explaining an example in which a gas and CO are detected by one semiconductor sensor.

Specific embodiments of the present invention will be described below with reference to the drawings. The alarm of this embodiment is a gas/CO alarm that detects and alarms gas leaks and CO (carbon monoxide) generation, and is installed, for example, on a wall surface indoors. Of course, the present invention may also be applied to a combined alarm equipped with alarm functions other than gas/CO alarms, such as a fire alarm.

Figure 1 is a functional block diagram showing an example of the schematic configuration of an alarm device according to one embodiment of the present invention. Figure 2 is a front view showing an example of the exterior of the alarm device in Figure 1.

As shown in FIG. 1, the gas/CO alarm AL (hereinafter simply referred to as the "alarm AL") according to this embodiment includes an alarm stop switch 20 connected to a microcomputer (hereinafter referred to as μCOM) 10 (controller), a gas sensor 30 (second sensor), and a CO sensor 40 (first sensor).

The gas sensor 30 is a gas leak detection sensor that detects the concentration of flammable gases such as city gas and LP gas (propane gas). The gas sensor 30 can be, for example, a semiconductor sensor or a catalytic combustion sensor, but since a current is passed through a platinum wire and the sensor element is heated to about 300°C, it requires a larger current consumption than the CO sensor 40 described below.

The CO sensor 40 is a CO detection sensor that detects the concentration of carbon monoxide (CO gas), and can be, for example, a semiconductor sensor or an electrochemical sensor. With a semiconductor sensor, CO can be detected at a lower temperature compared to gas leak detection using a semiconductor sensor, so a relatively small current needs to be passed through the platinum wire. Also, with an electrochemical sensor, the sensor itself outputs a sensor current according to the CO gas concentration, so the current consumption required by the sensor is almost zero.

μCOM 10 has a CPU (central processing unit) 10a, a ROM 10b, and a RAM 10c. The CPU 10a is a control means that performs various processes according to programs, and drives the gas sensor 30 and the CO sensor 40. When the CPU 10a receives a supply of power voltage and starts operating, it starts driving the CO sensor 40, and starts driving the gas sensor 30 with a delay from the point in time when the CO sensor 40 started to be driven. The ROM 10b stores the processing programs executed by the CPU 10a. The RAM 10c is a freely readable and writable memory that has a work area used in various processing steps in the CPU 10a, a data storage area for storing various data, and the like.

The alarm AL also includes an audio output circuit 60 and a speaker 70 as sounding means, an incomplete combustion alarm lamp 80, a gas leak alarm lamp 90, a fault notification lamp 100, and an EEPROM 110, all of which are connected to the μCOM 10. The audio output circuit 60 is a circuit for issuing an audio alarm when a gas leak is detected, when CO generation is detected, etc. The incomplete combustion alarm lamp 80 is an alarm display means for displaying an alarm when CO is detected. The gas leak alarm lamp 90 is an alarm display means for displaying an alarm when a gas leak is detected. The fault notification lamp 100 is a fault display means for reporting a fault when a fault occurs. The EEPROM 110 is a non-volatile memory, and is a storage means for storing preset gas leak alarm thresholds, incomplete combustion alarm thresholds, etc.

The incomplete combustion warning lamp 80 is, for example, an LED that emits yellow light, the gas leak warning lamp 90 is, for example, an LED that emits red light, and the malfunction notification lamp 100 is, for example, an LED that emits green light. Furthermore, the incomplete combustion warning lamp 80, the gas leak warning lamp 90, and the malfunction notification lamp 100 are controlled to be turned on and off by the μCOM 10.

The alarm AL also includes a power supply circuit 50 that supplies power from an external DC power supply (Vcc) to each of the components, such as the μCOM 10, the gas sensor 30, and the CO sensor 40. Note that in FIG. 1, the power supply lines from the power supply circuit 50 to each component other than the CPU 10a, the gas sensor 30, and the CO sensor 40 are not shown.

The alarm stop switch 20 is a push button switch, and pressing the push button portion 20a supplies an alarm stop signal to the CPU 10a.

The alarm AL is installed in a suitable location by an installer's worker, and when the power is turned on, it automatically performs an initial inspection operation to determine whether the gas sensor 30 and CO sensor 40 are normal (fault detection). The initial inspection operation is performed during the initial alarm prevention time, which is a fixed period of time (e.g., 60 seconds) from the time that the μCOM 10 starts operating. The alarm AL then performs a monitoring mode operation to detect gas leaks and CO gas generation.

During monitoring mode operation, the CPU 10a monitors the gas sensor 30 and the CO sensor 40 at a predetermined time interval (for example, every 5 seconds). When an abnormality occurs in the monitoring area and the gas sensor 30 detects a gas concentration above the threshold, the CPU 10a notifies the gas leak in a predetermined alarm format. For example, the CPU 10a notifies the gas leak by driving the audio output circuit 60 to output a voice message (or alarm sound) from the speaker 70 and blinking the gas leak alarm lamp 90. When the CO sensor 40 detects CO above the threshold, the CPU 10a similarly drives the audio output circuit 60 to output a voice from the speaker 70 and blinks the incomplete combustion alarm lamp 80 to notify the CO alarm. When a malfunction occurs, the CPU 10a blinks the malfunction alarm lamp 100 to indicate the malfunction. The CPU 10a stops the alarm by detecting the pressing of the push button portion 20a of the alarm stop switch 20 in the alarm state.

Figure 2 is a front view showing an example of the appearance of an alarm device AL. The alarm device AL is formed in a rectangular shape when viewed from the front. The alarm device AL has slits arranged at intervals in the vertical direction in the center of the front, and the gas sensor 30 is housed inside the slits. The alarm device AL also has a similar slit in the upper right part of the front, and the CO sensor 40 is housed inside the slits. The alarm device AL has multiple holes in the lower left part of the front, and the speaker 70 is housed inside the holes. The alarm device AL has an incomplete combustion alarm lamp 80, a gas leak alarm lamp 90, and a malfunction notification lamp 100 arranged at intervals from the top in the lower right part of the front. The push button portion 20a of the alarm stop switch 20 is provided in the lower center part of the front of the alarm device AL. The appearance of the alarm device AL is not limited to that shown in Figure 2, and may be, for example, circular when viewed from the front.

(Operation immediately after power is turned on)
The operation of the alarm device AL immediately after it is powered on will be described below with reference to Figures 3 and 4. Figure 3 is a time chart showing an example of the operation of the alarm device AL from powering on to the completion of the initial inspection, and Figure 4 is a graph showing an example of the change in power supply voltage and current consumption from powering on to the completion of the initial inspection of the alarm device AL. In Figures 3 and 4, the horizontal axis indicates time, and times t0 to t4 indicate timing common to Figures 3 and 4. In the following example, it is assumed that a power supply voltage is supplied from an external 24V DC power supply (external power supply) to an alarm device AL with a power consumption of 1.5 W. Also, in the following example, it is assumed that a catalytic combustion sensor is used as the gas sensor 30, and an electrochemical sensor is used as the CO sensor 40. The alarm device AL is installed at the installation site by workers from an installation company or the like, and is connected to an external power supply.

As shown in FIG. 3, when power supply from an external power source to the alarm AL (μCOM10) begins (time t0), the power supply voltage gradually rises from 0V. When the power supply voltage reaches a voltage (first voltage value, for example 10V) that enables operation of μCOM10 (time t1), μCOM10 begins operation, i.e., the alarm AL is activated. At time t1, μCOM10 supplies a predetermined power supply to the CO sensor 40 to start operation, and begins inspection of the CO sensor 40 (detection of electrochemical CO sensor failure).

The power supply voltage further rises and reaches a predetermined value (second voltage value, 24 V in this example) (time t2) and stabilizes. After that, when a predetermined time (e.g., 15 seconds) has elapsed (time t3) from the start of the inspection of the CO sensor 40 (time t1), μCOM 10 ends the inspection of the CO sensor 40 and stops driving the CO sensor 40. Also, at time t3, μCOM 10 starts the heater power supply of the gas sensor 30 (drives the catalytic combustion sensor heater) and starts inspecting the gas sensor 30. After that, when the temperatures of the sensor element and reference element of the gas sensor 30 become constant and the inspection of the gas sensor 30 is completed (time t4), the alarm AL becomes capable of detecting gas leaks and CO gas generation normally and transitions to the execution of monitoring mode operation.

In Figure 4, symbol Vcc indicates the change in power supply voltage supplied to the alarm device AL, symbol IA indicates the change in current consumption in the alarm device AL, and symbol IB indicates the change in current consumption in the comparison alarm device. The comparison alarm device has a similar configuration to the alarm device AL, but differs from the alarm device AL in that when the power supply voltage is received and the μCOM begins operation, it drives both the CO sensor and gas sensor simultaneously. In other words, the comparison alarm device is an alarm device that does not implement measures to prevent an increase in current consumption by the alarm device AL of this embodiment.

As shown in Figure 4, the current consumption IB of the comparison alarm reaches approximately 150 mA immediately after it starts operating, and then decreases as the power supply voltage Vcc rises. On the other hand, the current consumption IA of the alarm AL increases gradually after it starts operating, without a sudden increase.

As described above, according to the alarm device AL of this embodiment, at startup (the point when μCOM10 starts operating), first, the electrochemical CO sensor 40, which consumes almost zero current, is driven, and the CO sensor 40 is inspected. After that, the alarm device AL drives the catalytic combustion gas sensor 30. That is, after the power is started, the alarm device AL does not drive the gas sensor 30, which consumes a large current, during the transitional period until the power supply voltage reaches a predetermined value, and only drives the CO sensor 40, which consumes a small current. With this configuration, during the transitional period after the power is started, a large current does not flow through the alarm device AL, and the alarm device AL can be started with the minimum current at which the alarm device AL can operate. In this way, by keeping the startup current of the alarm device AL small, stable startup operation can be achieved without power supply shutdown or current limiting. In addition, the alarm AL starts driving the CO sensor 40 as soon as the CPU 10a starts operating, so the alarm AL can be started up more quickly and perform its alarm function than if the sensor drive was not started until the power supply voltage had risen sufficiently after the CPU 10a started operating.

The maximum current consumption IA of the alarm AL during the transitional period after power is turned on (the period when the power supply voltage is equal to or greater than 0 V and less than the specified value of 24 V) does not exceed the normal current consumption (approximately 63 mA when power consumption is 1.5 W and the power supply voltage is the specified value of 24 V). This means that the installer of the alarm AL does not need to prepare a power supply with a larger capacity than necessary.

The alarm AL starts driving the CO sensor 40 when the power supply voltage Vcc is 10V (first voltage value), and starts driving the gas sensor 30 after the power supply voltage Vcc rises to 24V (second voltage value). This allows the gas sensor 30 to be driven with less current consumption than when driven at 10V. In addition, by starting to drive the gas sensor 30 when the power supply voltage Vcc is stable, current consumption can be kept to a minimum.

By stopping the operation of the CO sensor 40 and then starting the operation of the gas sensor 30, the alarm AL can reduce current consumption compared to when the CO sensor 40 and the gas sensor 30 are operated simultaneously.

The alarm AL can complete the initial inspection without extending the initial inspection time even if the start time of the gas sensor 30 is delayed. In general, in a combined alarm, such as an alarm having a gas leak detection function and a CO detection function, after power is turned on, there is a certain waiting time (initial alarm prevention time, for example, 60 seconds) until normal gas detection is possible, and during this time the alarm operation is stopped. During this initial alarm prevention time, the alarm waits for the temperature of the gas leak detection and CO detection gas sensors (sensor element and reference element) to become constant (wait for stabilization) and determines whether the gas sensor is normal or not (fault detection). In the alarm AL of this embodiment, during the initial alarm prevention time (the time from time t1 to time t4), μCOM10 first inspects the CO sensor 40 (for example, for 15 seconds), and then turns on the heater power supply of the contact combustion sensor to drive the gas sensor 30. The catalytic combustion gas sensor 30 usually requires a stabilization waiting time of about 40 seconds, but even if the heater power for the gas sensor 30 is turned on after the inspection of the CO sensor 40 is completed, the initial inspection can be completed within 60 seconds. In this way, with the alarm AL, even if the inspection of the gas sensor 30 and the inspection of the CO sensor 40 are not started at the same time, and the inspection of the gas sensor 30 is performed after the inspection of the CO sensor 40, the initial inspection can be completed without extending the initial alarm prevention time.

The present invention is not limited to the above-described embodiment, and can be modified, improved, etc. as appropriate. In addition, the material, shape, dimensions, values, form, number, location, etc. of each component in the above-described embodiment are arbitrary as long as they can achieve the present invention, and are not limited. For example, in this embodiment, the gas sensor 30 is started to be driven when the inspection of the CO sensor 40 is completed, but the gas sensor 30 may be started to be driven at a timing after the inspection of the CO sensor 40 is completed. For example, if the inspection of the CO sensor 40 takes 15 seconds, the gas sensor 30 may be started to be driven 15 seconds after the inspection of the CO sensor 40 is started.

In addition, in the above-described embodiment, an electrochemical sensor and a catalytic combustion sensor are used as the CO sensor 40 and the gas sensor 30, respectively, but the CO sensor 40 and the gas sensor 30 may be configured as a single semiconductor sensor rather than separate sensors. Even if the alarm AL detects multiple types of gas (CO detection and gas leak detection) using a single semiconductor sensor, the current consumption at startup can be reduced by starting operation from the CO sensor, which functions with less current consumption.

Figure 5 is a diagram for explaining an example of detecting gas and CO with one semiconductor sensor, where (a) shows an example starting with gas detection when the power is turned on, and (b) shows an example starting with CO detection when the power is turned on. In a semiconductor sensor capable of detecting both gas and CO with a single sensor, the heater is pulse-driven alternately at a high voltage (fourth voltage) and a low voltage (third voltage), detecting CO at a low voltage and detecting gas at a high voltage. Normally, as shown in Figure 5(a), when the power is turned on, that is, when the microcomputer starts operating (when the alarm is activated), the microcomputer drives (heats up) the heater at a high voltage (e.g., 0.9 V, current consumption is about 130 mA) and maintains that state for 5 seconds. After that, the microcomputer drives (heats down) the heater at a low voltage (e.g., 0.2 V, current consumption is about 60 mA) and maintains that state for 15 seconds. The semiconductor sensor detects gas when the temperature is in a range suitable for gas detection just before heat down. Also, the semiconductor sensor detects CO when the temperature is in a range suitable for CO detection just before heating up. This counts as one cycle, and the alarm performs three cycles within the initial alarm prevention time of, for example, 60 seconds, and then transitions to a monitoring state (monitoring mode operation).

However, in the case of an alarm AL driven by a DC power supply, as shown in FIG. 5(a), if the alarm starts with heat-up when powered on, current consumption will be large. Therefore, as shown in FIG. 5(b), the alarm AL detects CO by starting operation with heat-down when powered on (driving the heater of the semiconductor sensor at a low voltage). Because CO can be detected at a lower temperature than gas leak detection, CO can be detected with less current consumption (e.g., about 60 mA) than the current consumption required for gas leak detection (e.g., about 130 mA). In this way, even when CO detection and gas leak detection are performed with a single semiconductor sensor, the alarm AL can reduce current consumption at startup by starting operation with the CO sensor, which functions with less current consumption.

The features of the alarm device according to the embodiment of the present invention described above will now be briefly summarized and listed below in [1] to [6].
[1] A first sensor (CO sensor 40) for detecting a first gas;
a second sensor (gas sensor 30) that detects a second gas different from the first gas and consumes a larger current than the first sensor;
A control unit (CPU 10a) that drives the first sensor and the second sensor,
When the control unit receives a power supply voltage and starts operating (time t0), the control unit starts driving the first sensor (time t1), and starts driving the second sensor with a delay from the time when the control unit starts driving the first sensor (time t3).
Alarm.
[2] The alarm described in [1] above, wherein the control unit starts driving the first sensor when the power supply voltage is a first voltage value, and starts driving the second sensor when the power supply voltage is a second voltage value higher than the first voltage value.
[3] The alarm device according to the above-mentioned [2], wherein the second voltage value is a voltage value when the power supply voltage is stable.
[4] The alarm device according to any one of the above-mentioned [1] to [3], wherein the control unit starts driving the second sensor after stopping driving of the first sensor.
[5] The alarm device described in any one of [1] to [4] above, wherein the control unit drives the first sensor to perform a fault diagnosis of the first sensor, and starts driving the second sensor after a time required for the fault diagnosis has elapsed.
[6] The first sensor and the second sensor are constituted by a single sensor,
The alarm device described in any one of [1] to [4] above, wherein the single sensor detects the first gas in a state where a third voltage is applied, and detects the second gas in a state where a fourth voltage higher than the third voltage is applied.

AL Gas/CO alarm (alarm)
10μCOM
20 Alarm stop switch 30 Gas sensor 40 CO sensor 50 Power supply circuit 60 Audio output circuit 70 Speaker 80 Incomplete combustion alarm lamp 90 Gas leak alarm lamp 100 Malfunction notification lamp

Claims (6)

a first sensor for detecting a first gas;
a second sensor that detects a second gas different from the first gas and consumes a larger current than the first sensor;
a control unit that drives the first sensor and the second sensor,
When the control unit receives a supply of power supply voltage and starts operating, it starts driving the first sensor, and starts driving the second sensor with a delay from the point in time when the control unit started driving the first sensor. The alarm device according to claim 1 , wherein the control unit initiates activation of the first sensor when the power supply voltage is at a first voltage value, and initiates activation of the second sensor when the power supply voltage is at a second voltage value higher than the first voltage value. The alarm according to claim 2 , wherein the second voltage value is a voltage value when the power supply voltage is stable. The alarm device according to any one of claims 1 to 3, wherein the control unit starts driving the second sensor after stopping driving of the first sensor. 5. The alarm device according to any one of claims 1 to 4, wherein the control unit drives the first sensor to perform a fault diagnosis of the first sensor, and starts driving the second sensor after a time required for the fault diagnosis has elapsed. the first sensor and the second sensor are configured as a single sensor,
5. The alarm device according to any one of claims 1 to 4, wherein the single sensor detects the first gas in a state where a third voltage is applied to it, and detects the second gas in a state where a fourth voltage higher than the third voltage is applied to it.

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