JPS5837544A - Photoelectric type smoke detector - Google Patents

Abstract

PURPOSE:To prevent the titled device from malfunctions such as noises by timing for a prescribed period from the time a smoke detecting output exceeds a standard value and, when the smoke detecting output is still larger than the standard value after passing the prescribed period, generating an alarm. CONSTITUTION:When smoke is generated in detection atmosphere and the output of an amplifier 23 exceeds standard voltage V1, a comparator 24 outputs a high level signal. The output is applied to an up/down (U/D) controlling terminal of an U/D counter and up-counting is executed. When the U/D counter counts up two input pulses, a high level signal is outputted from an output terminal SX and a buzzer 6 is continuously driven through an OR circuit 5 to indicate the generation of smoke for a comparatively long period. In case of tobacco smoke, the U/D counter 8 counts up the fall of the 1st pulse outputted from the OR circuit 9, but the smoke disappears before the 2nd decayed pulse is applied after a few seconds, so that the U/D terminal is turned to the low level and no up-counting and buzzing take place.

Description

[Detailed description of the invention] This invention relates to a rechargeable smoke detector.

Photoelectric smoke detectors are well known in the past.

The circuit connection diagram is shown in FIG.

In Fig. 1, 1 is a pulse oscillation circuit that generates two types of pulse signals, 2 is a smoke detection circuit that emits φ power in response to smoke (sensing smoke), 3 is a built-in battery, and 4 is a voltage drop in the built-in battery 5. 5 is an OR circuit that detects this, and when it receives a signal from either the smoke detection circuit 2 or the voltage drop detection circuit 4, it derives this signal and operates the buzzer 6. Pulse oscillation In the circuit 1, two types of pulse signals ta and b are generated which have the same cycle and rise timing but different Tehalus widths.The cycles of these pulse signals a and b are 5 to 1Q.
The pulse width of the pulse signal a is selected to be about 0.2 m5ec, and the pulse width of the pulse signal S is selected to be extremely small, about 10 to 30m8ec. 2nd A
Pulse signals a and b are shown in the figure, but for convenience, the pulse widths are enlarged compared to the period.

The smoke detection circuit 2 includes a light projecting element 21. Light receiving element 22° amplifier 23. It consists of a comparator 24.

When the light projecting element 21 receives the pulse signal a from the oscillation circuit 1, it is periodically turned on for a minute period only during the pulse width period. The pulsed light from the light emitting element 21 is scattered when smoke is present, so the scattered light is received by the light receiving element 22, and the pulsed light is sent to the amplifier 2.
3 and applied to one end of the input of the comparator 24 (Fig. 2A, C). The comparator 24 compares the output of the amplifier 23, that is, the smoke detection voltage, with the reference voltage v1, and derives an output if the smoke detection voltage is larger. do. The comparator 24 includes a retriggerable monostable multivibrator or an R-8 free lag flop circuit to maintain the output at a high level for a period when the smoke detection voltage C is continuously higher than the reference voltage V1. There is. The output signal of the comparator 24 is as shown in FIG. 2A (d). This high level output signal of the comparator 24 is not a smoke detection signal.

The signal is applied to the buzzer 6 via the OR circuit 5 and causes the buzzer 6 to sound continuously.

Further, assuming that the voltage of the battery 3 has decreased although no smoke is generated, the voltage decrease detection circuit 4 detects the voltage decrease. That is, when the battery voltage is smaller than the voltage divided by the voltage dividing circuit 41 and the reference voltage v2 by the comparator 42, and the power supply voltage divided by 1 is smaller than the reference voltage v2, a pulse is generated as shown in FIG. 2B e. Pulse width period of signal S, comparator 4
The high repe yvfi1 is derived from the output of 2. This signal is applied to the buzzer 6 via the OR circuit 5, causing the buzzer 6 to ring intermittently.

As described above, according to the conventional optical smoke detector shown in FIG. 1, the occurrence of smoke can be detected by the continuous sounding of the buzzer, and the drop in battery voltage can be detected by the intermittent sounding of the buzzer.

However, the above-mentioned conventional photoelectric smoke detectors tend to generate non-fire alarms due to short-lived but highly concentrated smoke such as cigarette smoke, flashlights, etc. It has the disadvantage that it is prone to malfunction if noise is introduced.

The object of the present invention is to eliminate the drawbacks of the conventional photoelectric smoke detectors described above, and to provide a photoelectric smoke detector that is less prone to non-fire alarms and malfunctions.

In order to achieve the above object, the photoelectric smoke detector of the present invention is provided with a means for timing a predetermined time from the time when the smoke detection output becomes higher than the reference value, and after the elapse of a predetermined time by this timing means. The standard value also features a buzzer that sounds when the smoke detection output is high.

The present invention will be further explained in detail below with reference to large-scale embodiments shown in the drawings.

FIG. 3 is a circuit block diagram of a photoelectric smoke detector showing one embodiment of the present invention. In fig.

Oscillation circuit 1. Smoke detection circuit 2. Power battery 3. Voltage drop detection circuit 4. OR circuit 5. Since the buzzer 6 is the same as the conventional one shown in FIG. 1, detailed explanation will be omitted.

However, the output of the smoke detection circuit 2, that is, the output terminal d of the comparator 24 is connected to one end of the input of the AND circuit 7, and the U/D control terminal of the n-ary up/down counter 8 is connected. Furthermore, the configuration is different from that shown in FIG. 1 in the following points. A particular feature is that an up/down counter 8 is provided. Output of AND circuit 7 and oscillation circuit 1
The pulse signal a of the up/down counter 8 is connected so as to be applied to the input terminal CP of the up/down counter 8 via the OR circuit 9. The up/down counter 8 outputs a smoke detection output, that is, a high level signal, to the U/D control terminal, and when a pulse (1, number) is applied to the input terminal CP, a signal is generated.
Up count L, U/D, ul when descending
The first step is that the smoke detection output cannot be applied to the control terminal.

That is, when a manual pulse is applied by applying a low level signal, a down count is performed at the falling edge of the input pulse.

When the number of calls H reaches the maximum number, the output Sm is applied to the clear terminal CL, and the down counter itself is cleared. Further, the Sx output (J) terminal of the up/down counter 8 is connected to the curved end of the input of the AND circuit 70, and is also connected to one end of the input of the OR circuit 5. The Sx output terminal outputs an output (1111, that is, a high level (No. 8) when the count value of the up/down counter 8 reaches 2.

In the circuit of Fig. 5, smoke is constant in the detection atmosphere.
When the output of the amplifier 23 becomes larger than the reference 1rfv1 as shown in FIG. 4A, C, the comparator 24 outputs a high level signal No. 4, as shown in FIG. 4A, d.

This high level signal is then sent to the up/down counter 8.
Since this high level signal is applied to the U/D control terminal of the U/D control terminal, the up/down counter 8 receives the down signal of the output g of the OR circuit 9 and performs an up/down operation. Count.

While the high level) V signal is not derived to the AND circuit 7,
9. The pulse signal d of the swing circuit 1 is applied to the CP terminal of the up/down counter 8 via the OR circuit 9, and its fall is counted. When the up/down counter 8 counts two input pulses, a pie level signal (
(see diagram 4A). This high level signal is applied to the buzzer 6 via the OR circuit 5, causing the buzzer 6 to continuously sound. This continuous rumble indicates a relatively long period of smoke generation. Note that when the SX output terminal of the up/down counter 8 becomes a high level, the smoke detection output goes to the reference terminal circuit 7.
Since the output of the OR circuit 9 is at a high level and the output of the OR circuit 9 (Fig. 4A, g) does not fall to the - level, the up/down counter 8 does not increase the E count from then on.

After the buzzer sounds, when the smoke temporarily disappears, the amplification Xg23
Since the smoke detection output of is smaller than the reference jj'L Vl, the output of the comparator 24 is low level (4th A, /+d
&M), therefore, a low level signal is added to the U/D control terminal of the up/down counter 8, and upon receiving the falling signal of the OR circuit 9, the counter counts down. Therefore, since the Sx terminal of the up/down counter 8 changes from a high level signal to a low level No. 18, the output j of the OR circuit 5 also changes from a high level to a low level, and therefore the buzzer B also stops sounding. Next, the up/down counter 8 counts up until the smoke density exceeds the combing level 1 again.

The Sx output terminal goes high and the buzzer starts sounding again.

Next, suppose, for example, that a cigarette is being smoked in the detection atmosphere. Since the cigarette smoke is thick, the J1 sensed output will naturally be higher than the standard direct v1, and the output of the comparator 24 will also be at a high level, and the up/down counter E) will detect the 17 down of the output of the OR circuit 9 from one shot. I receive it and count up, but
A few seconds later, by the time the next ＼γ descent/seasonal item was available in January, the cigarette's Flv+ had disappeared.

Since the output of comparator 24 has fallen to low level.

U/D control J terminal 0 high level to low level 1
8, and even if the pulse signal i from the 9 oscillation circuit 1 is applied to the input terminal CP of the up/down counter 8 through the OR circuit 9, it will not count up. Therefore, a high level signal cannot be obtained at the Sx terminal, and therefore the buzzer 6 does not sound.

In a normal state where no smoke is generated, the output of the amplifier 23, that is, the smoke detection output, is lower than the reference value v1, so the comparator 24
The output of is at a low level (see FIG. 4B c, d), and a low level signal from the U/D control terminal of the up/down counter 8 is applied.

Since the pulse signal from the oscillation circuit 1 is applied to the OR circuit 9, the up/down counter 8 counts down in response to the fall of this pulse signal.

In this case, when the up/down counter 8 reaches the maximum count value, the counter itself is cleared by the output from the terminal Sm, and the count state is set to zero, so that it is always in a state of waiting for counting.

Further, in the circuit shown in FIG. 5, when the voltage of the power supply '+tj and the battery 6 decreases, the voltage drop detection circuit 4 detects this.

The buzzer 6 is made to sound intermittently through the OR circuit 5 in the same way as the conventional circuit shown in FIG.

In the above embodiment, the Sx output of the up-down counter is obtained by the second input pulse, but of course it is not necessary to limit it to 2, and the number of seconds or less the non-fire alarm should be, or how long the pulse signal period should be. It may be selected as appropriate, taking into account the following.

Furthermore, in the above embodiment, fire alarms and non-fire alarms are distinguished from each other by using an up/down counter and by the presence or absence of a constant count output. After a certain period of time has elapsed, if the smoke detection output is still being output after the certain period of time has elapsed, a fire may be detected and an alarm may be issued.

As described above, according to the photoelectric smoke detector of the present invention, there is provided a means for timing a predetermined time after a smoke detection output of a certain level or higher is obtained, and if the smoke detection output still exists after the elapse of this predetermined time, By eliminating the sensitivity to alarm activation, flash detection, and other traumatic noises, it is possible to obtain a photoelectric smoke detector that does not cause fire alarms or has fewer malfunctions.

[Brief explanation of the drawings] Figure 1 is a circuit connection diagram showing a conventional photoelectric smoke detector;
Figure A is a signal waveform diagram of each part of the photoelectric smoke detector shown in Figure 1 when smoke is generated, Figure 2B is a diagram of signal waveforms of each part of the same sensor shown in Figure 1 when the battery voltage drops, and Figure 13 is a diagram of the present invention. A circuit connection diagram of a photoelectric smoke detector showing one embodiment, Fig. 4A is a signal waveform diagram of each part of the photoelectric smoke detector shown in Fig. 6 when smoke is constant, and Fig. 4B is a normal diagram of the same sensor. FIG. 4 is a signal waveform diagram of each part when the battery voltage drops. 1: Oscillator circuit, 2: Smoke detection circuit, 3: Battery. 4: Voltage drop detection circuit, 5.9: OR circuit. 6: buzzer, 7: AND circuit, 8 near-tub down counter, 21: light emitting element. 22: Light receiving element, 23: Amplifier. 24/42: Comparator, 41: Voltage dividing circuit. 1st old 3tl 'l1li 2AΣ 2BII

Claims (1)

[Claims] (1) A pulse oscillation circuit, a light source that emits a light bulb by the pulses of the pulse oscillation circuit, and a light signal generated by the light pulse light source and the light source being scattered by smoke. A smoke detection circuit including a circuit for receiving scattered light, a comparator that compares the output of the light receiving circuit with a reference value and outputs an output when the output of the light receiving circuit exceeds the reference value, and a comparator output of the smoke detection circuit. In the photoelectric smoke detector, which is similar to the means for receiving and issuing an alarm, means is provided for measuring a certain period of time from the time when the comparator outputs an output indicating that the smoke detection output is higher than the reference value. (2) The time measuring means is a counter and the comparator is a reference value. Counting starts from the moment when the output indicating that the smoke detection output is large is reached, and at the predetermined count output -
The photoelectric smoke detector according to claim 1, characterized in that an IJ warning means is activated. (3) The counter is an up/down counter.* It counts by receiving the pulse signal of the MiJ pulse oscillation circuit, and when the smoke detection output from the comparator is greater than the reference value, it counts up and detects smoke. Claim 2, characterized in that when the sensed output is smaller than the reference value, a down count is performed, and when the count value of this up/down counter reaches a predetermined value, the first alarm means is operated. The photoelectric smoke detector listed