JPH021668Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is a gas alarm equipped with an initial delay circuit that stops the gas detection function for a predetermined period of time after the power is turned on. The present invention relates to a gas alarm device that displays the elapsed time of a delay time using different luminous colors.

The initial delay circuit stops the gas detection function until the gas sensor's characteristics stabilize when the power is turned on. During this time, the gas alarm will display an initial delay. The display method includes a method of blinking the power lamp during the initial delay time T, as shown in Figure 1a,
As shown in FIGS. 1b and 1c, there is a method (c) in which the power lamp is left on and the alarm lamp is turned on during the initial delay time T (b).

This initial delay time is generally set to about 3 minutes, and inspection cannot begin unless you wait for the initial delay time after installing the gas alarm and turning on the power. Time feels long. However, if you can know the elapsed time or remaining time, this time will not feel so long. The present invention has been developed in view of the above circumstances, and an object of the present invention is to provide a gas alarm equipped with a function of displaying the remaining time of the initial delay time by changing the color of the emitted light.

A preferred embodiment of the present invention illustrated in FIG. 2 will be described in detail below.

In FIG. 2, the upper part is a general initial delay circuit, and the lower part is a remaining time display circuit according to the present invention.

The initial delay circuit is composed of a comparator 1, a resistor R, a capacitor C, and two resistors 2 and 3 for generating a comparison voltage. The capacitor C is charged via the resistor R from the time the power is turned on, and when the terminal voltage of the capacitor C exceeds the comparison voltage, the output signal of the comparator 1 is inverted and the initial delay time ends.

The terminal voltage of this capacitor C is input to a voltage follower formed by an operational amplifier 4 and impedance converted. The output of the operational amplifier 4 is connected via a resistor 5 to a two-color light emitting diode 6, for example a green light emitting diode G, and is also connected via a Zener diode 7 and a resistor 8 to the base of a PNP transistor 9. The emitter of the transistor 9 is connected to the power supply Vcc, and the collector is connected to the two-color light emitting diode 6, for example, a red light emitting diode R, via a resistor 10.

Since the operational amplifier 4 has a gain of 1, the terminal voltage of the capacitor C is directly supplied to the output. Therefore, immediately after the power is turned on, its output is zero, so
The green light emitting diode G does not light up. At this time, the transistor 9 is turned on because the base current flows through the resistor 8 and the Zener diode 7.
Turn on the red light emitting diode R.

As time passes, charge is gradually accumulated in the capacitor C, and the terminal voltage of the capacitor C increases. At the same time, the output voltage of the operational amplifier 4 also increases.

As a result, the base current of the transistor 9 decreases, and the current supplied to the red light emitting diode R decreases, and conversely, the current supplied to the green light emitting diode G increases, and the green light emitting diode G starts emitting light. Here, current flows little by little through the red and green light emitting diodes, and when both of them emit light, the two-color light emitting diode 6 emits yellow light.

When the charge in the capacitor C is further accumulated and the terminal voltage increases, the green light emitting diode is finally turned on and the red light emitting diode is turned off. here,
By making the voltage of the Zener diode 7 equal to the value obtained by subtracting the comparison voltage of the initial delay circuit and the base-emitter voltage of the transistor 9 from the power supply voltage, the two-color light emitting diode 6 becomes completely green when the initial delay is completed. Transition to emit light.

FIG. 3 shows an example of voltage waveforms at various parts during this initial delay time.

FIG. 3a shows the change in the terminal voltage of capacitor C of the initial delay circuit. Since the operational amplifier 4 feeds back its output directly to its inverting input and acts as an impedance converter with a gain of 1, a voltage signal having the same value as the terminal voltage of the capacitor C appears at the output.

Figure 3b shows the change in the bias current of the transistor 9. When the power is turned on (t=0), the anode of the Zener diode 7 is zero, so the maximum current flows, and the output of the operational amplifier 4 is compared to the initial delay circuit. When the voltage reaches the voltage, the voltage difference between the output voltage of the operational amplifier and the voltage obtained by subtracting the base-emitter voltage of the transistor 9 from the power supply voltage becomes smaller than the Zener voltage of the Zener diode 7, and the Zener diode 7 becomes non-conducting. Therefore, the bias current becomes zero.

Figure 3c shows the current changes in the two-color light emitting diode 6, the green light emitting diode G, and the operational amplifier 4.
A current approximately proportional to the output voltage flows.

FIG. 3d shows the current variation of the red light emitting diode R, and shows that the current reaches zero before the initial delay time elapses.

In this way, the two-color light emitting diode 6 emits red light at the beginning of the initial delay time, then red and green are mixed to change to yellow, and then to green. The change in the emitted light color from red to green indicates that the initial delay time is becoming shorter.
The mixing ratio of red and green is Zener diode 7
and resistors 8 and 10.

As described above, it is possible to know the transition of the initial delay time by the change in the light emission color of the two-color light emitting diode 6, and it is possible to grasp the remaining time until the initial delay time is canceled.

[Brief explanation of drawings]

Figures 1a, b, and c are diagrams illustrating the operation of a conventional gas alarm at the time of initial delay, Figure 2 is a diagram illustrating the initial delay circuit and initial delay remaining time display circuit according to the present invention, and Figure 3. a, b, c, and d are diagrams showing changes in voltage and current of main parts of the circuit of FIG. 2; 1... Comparator, 4... Operational amplifier, 6... Two-color light emitting diode.

Claims (1)

[Scope of utility model registration request] A gas alarm equipped with an initial delay circuit that has a resistor and a capacitor connected in series with the power supply, and a comparator that compares the terminal voltage of this capacitor with a comparison voltage and stops the gas detection function for a predetermined period of time after the power is turned on. , a two-color light emitting diode capable of mixing emitting colors that displays the initial delay remaining time by changing the emitting color, an amplifier that receives the terminal voltage of the capacitor of the initial delay circuit and outputs a voltage according to the value, and an emitter that is connected to the power source. a transistor connected to the transistor and having its collector connected to one of the two-color light-emitting diodes via a resistor, a series-connected resistor, a Zener diode, and a resistor whose bases are connected to the other of the two-color light-emitting diodes, A gas alarm, characterized in that the output of the amplifier is connected to a connection between the Zener diode and a resistor on the other side of the light emitting diode.