EP0122432A1 - Photoelectric smoke detector equipped with smoke detecting function test means - Google Patents
Photoelectric smoke detector equipped with smoke detecting function test means Download PDFInfo
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- EP0122432A1 EP0122432A1 EP84102465A EP84102465A EP0122432A1 EP 0122432 A1 EP0122432 A1 EP 0122432A1 EP 84102465 A EP84102465 A EP 84102465A EP 84102465 A EP84102465 A EP 84102465A EP 0122432 A1 EP0122432 A1 EP 0122432A1
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- output
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- signal
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- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B29/00—Checking or monitoring of signalling or alarm systems; Prevention or correction of operating errors, e.g. preventing unauthorised operation
- G08B29/12—Checking intermittently signalling or alarm systems
- G08B29/14—Checking intermittently signalling or alarm systems checking the detection circuits
- G08B29/145—Checking intermittently signalling or alarm systems checking the detection circuits of fire detection circuits
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- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B17/00—Fire alarms; Alarms responsive to explosion
- G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
- G08B17/103—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using a light emitting and receiving device
- G08B17/107—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using a light emitting and receiving device for detecting light-scattering due to smoke
Abstract
Description
- It has been known that the operating test of the smoke detector which detects presence of smoke by scattering of light caused by entry of smoke into the light from the light emitting element and falling onto the light receiving element is carried out by increasing, from the control panel, the output of the light emitting element to increase the output of the light receiving element with the-noise light scattered in all directions on the wall surfaces in the labyrinth. Nevertheless, none of the photoelectric smoke detectors of this kind has ever had such a provision for checking, by remote operation from the control panel, the important function the detector, i.e. whether the output of the light receiving element of the detector is within the normal level range which causes no false alarm, alarm failure nor delayed alarm.
- The purpose of this invention is to obtain a photoelectric smoke detector equipped with a smoke detecting function test means which, upon receipt of a signal sent from a control panel through lines connecting the smoke detector with the control panel, is capable of automatically, readily and precisely checking whether the output of the light receiving element in the smoke detector is within the normal level range, and of reporting to the control panel on the result of the check through the same lines. This invention is described below with reference to embodiments shown with figures.
- Figure 1 is a circuit diagram of an embodiment according to the present invention relating to the light scattering type smoke detector which detects presence of smoke by scattered light. Figure 2 is a circuit diagram of a control panel used for this embodiment.
- Shown in Figure 1 are as follows: Two
lines lines light emitting part 1 which comprises a light emitting element LE such as light emitting diode, and a drive circuit PD connected between the conductors a, b. Alight receiving part 2 comprising a light receiving element SB such as solar cell which receives light emitted by the light emitting element LE and scattered by smoke, and an amplifier AM to amplify the output of the light receiving element SB. Acomparison part 3 which comprises a comparator CM with its - terminal on the input side connected with the voltage as operating level at the junction of resistors ri, r2 of those resistors r1, r2, r3, r4 connected in series between the conductors a, b, and its + terminal on the input side connected with the output of the amplifier AM of thelight emitting part 2. The resistors r1, r2, r3, r4 are provided to determine a fire level, an upper level of the normal level range as a threshold level at which a false alarm is likely to be produced, and a lower level of the normal level range as a threshold level at which alarm failure or delayed alarm is likely to occur. A firediscriminating part 4 which .comprises an AND gate A1 and a latch Lt1 formed by NOR gates NR1, NR2. The AND gate A1 receives outputs of the pulse oscillator PO1 for synchronized signal, the comparator CM in thecomparison part 3 and a NOT gate N3 to the input terminal of which Q output of a monostable multivibrator MM2 in atimer circuit 9 described hereafter is applied. The latch Lt1 is set by output of the AND gate A1 and cleared by output of the NOT gate N2 in a resetsignal generating circuit 8 which is described hereafter. A signal generatingcircuit 5 which comprises a pulse oscillator PO2 and NAND gates NA1, NAz. The pulse oscillator PO2 is connected between the conductors a, b and generates pulse outputs with low frequency f1 and high frequency f2. The NAND gate NA1 receives the pulse output with frequency f1 and the output of the flip-flop circuit FF2 in a smoke detecting functiondiscriminating circuit 11 described hereafter. The NAND gate NA2 receives the pulse output with frequency f2 and the output of the gate NA1. Asignal transmission circuit 6 which comprises NOR gates NR8, NR9 and a series circuit connected between thelines lines discriminating part 4 has detected a fire and of a latch Lt3 formed by NOR gates NR6, NR7 in the smoke detecting functiondiscriminating circuit 11. The NOR gate NR9 receives outputs of the NOR gate NR8 and the NAND gate NAz in the signal generatingcircuit 5. The series circuit is formed by a diode D1, resistor r5 and a transistor T3 with a resistor r6 connected between the base and emitter. An additional circuit shown with dotted lines in the signal generatingcircuit 6 is provided for identifying an alarming detector at the control panel in case plural detectors are connected in parallel between the same lines l1, l2. An oscillator POs generating pulses which vary with each detector and have far higher frequencies than f1, f2 is connected between the conductors a, b. A transistor T5 is connected between the diode D1 and the resistor r5. Resistors r18 and r19 are connected between the conductor a and the base of the transistor T5, and between the base of the transistor T3 and the collector of the transistor T3 respectively. A capacitor C6 is connected between the oscillator P03 and the base of the transistor T5. With. the pulse signal from the oscillator P03, each pulse of the pulse signals with frequencies f1, f2 sent from each detector to thelines signal receiving circuit 7 which receives a single pulse signal with narrow width for test start and a single pulse signal with wide width for resetting which are sent out from the control panel shown in Figure 2. The signal receivingcircuit 7 is formed by resistors r7, r3 and a capacitor C2 which are connected in series between the conductors a, b; an output line d which is led from the junction between the resistor r8 and the capacitor C2 to a resetsignal generating circuit 8 and atimer circuit 9 described hereafter; and a transistor T4, conduction of which is controlled by voltage at the junction of the resistors r9, rio connected in series between thelines signal generating circuit 8 confirms receipt of the reset signal from the control panel and transmits the reset signal to the detector. The resetsignal generating circuit 8 is equipped with a capacitor C3 which is charged With output of thesignal receiving circuit 7 through a NOT gate N1 and a resistor rll, and produces the reset signal with the voltage of the capacitor C3 through the resistor r12 and NOT gate N2. Thetimer circuit 9 operates when thesignal receiving circuit 7 has received the test start signal from the control panel, and comprises a latch Lt2, resistors r13, r14, a capacitor C4, monostable multivibrators MM1, MM2 and AND gates A2, A3. The latch Lt2 is formed by NOR gates NR3, NR4 which are set by output of thesignal receiving circuit 7. The output of the latch Lt2 is sent to the monostable multiviblators MM1, MM2 having a short and long operating time respectively through the delay circuit formed by the resistor r13, capacitor C4 and resistor r14 to prevent thetimer circuit 9 from operating with the output of the latch Lt2 when thesignal receiving circuit 7 has received the reset signal from the control panel. The output of the monostable multivibrators MM1, MM2 are applied to the input terminals of the AND gates A2, A3. An operatinglevel changeover circuit 10 which changes over the operating level of the comparator CM in thecomparison part 3, and operates as follows. With the output of the AND gate A2 in thetimer circuit 9 transmitted through a diode D2 and a resistor r15, the transistor T1 becomes conductive and shorts the series circuit formed by resistors r3, r4. With the output of the AND gate As transmitted through a diode D3 and a resistor r16, the transistor Tz becomes conductive and shorts the resistor r4 alone. Thus, the voltage applied as operating level to the - terminal on the input of the comparator CM in thecomparison part 3 becomes the fire level of the light scattering type smoke detector while the both transistors T1, T2 are not conducting. As the transistor T1 become conductive, the voltage becomes the lower limit of the normal level range as a threshold level of the detector at which alarm failure or delayed alarm is likely to occur. As the transistor T2 becomes conductive, the voltage becomes the upper level of the normal level range as a threshold level of the detector at which a false alarm is likely to be produced. A smoke detecting functiondiscriminating circuit 11 which comprises AND gates A4, As, OR gate R1, R - S flip-flop circuit FF1, D-type (delayed) flip-flop circuit FF2, resistors r17, r18, capacitor C5, NOT gate N4, NOR gate NR5 and latch Lt3 formed by NOR gates NR6, NR7.' The AND gates A4, As are connected with the outputs of the pulse oscillator PO1 for synchronized signal, the comparator CM in thecomparison part 3 and AND gates A2, A3 in thetimer circuit 9. The R - S flip-flop circuit FF1 receives the output of the AND gate A4 as set input and the output of the OR gate R1 as reset input which is connected with the outputs of the AND gate As and the resetsignal generating circuit 8. The D type flip-flop circuit FF2 receives Q output of the flip-flop circuit FF1 as D input, the clock signal as CP input generated by the NOR gate NRs and the output of thecircuit 8 as reset input. The NOR gate NRs serving as clock signal generator is connected with the Q output of the monostable multivibrator MM2 in thetimer circuit 9 and the output of the NOT gate N4 to which the voltage of the capacitor Cs charged with the Q output through the resistor r17 is applied through the resistor r18. The latch Lt3 formed by the NOR gates NR6, NR7 receives the output of the NOR gate NR5 as set input and is cleared by output of the resetsignal generating circuit 8. - Shown in Figure 2 are; a d.c. power supply E; a detecting circuit M for abnormal signal with frequency f2 including a fire signal; a detecting circuit N for normal signal with frequency fl; a relay X which operates when a test start switch SW1 has closed; a relay Y which operates when a reset switch SW2 has closed; a test start signal generator TS which operates when the contact x1 of the relay X has closed; a reset signal generator RS which operates when the contact y1 of the relay Y has closed; a fire indicator lamp La1 which is lit through the break contact x4 of the relay X and the make contact m1 of the relay M; an abnormal indicator lamp La2 which is lit through the make contact xs of the relay X and the make contact m2 of the relay M; a normal indicator lamp La3 which is lit through the make contact x3 of the relay X and the make contact n1 of the relay N; a timer T which starts operating when the contact x5 of the relay X has closed; and a trouble indicator lamp La4 which is operated through the make contact t of the timer T and the break contacts m3, n2 of the relays M, N to indicate accidents such as trouble in the detector lines or interruption of the
lines - Firstly, operation of each part of this embodiment during the normal supervisory condition and in case of fire is described with reference to the time charts shown in Figure 3 (A). Shown in Figure 3 (A) are smoke density (1), voltage (2) on the
lines lines signal receiving circuit 7 is at L level as shown at the left part of Figure (3) because the transistor T4 is conducting. Consequently, in the resetsignal generating circuit 8, the output of the NOT gate N1 becomes H level. With this output the capacitor C3 is charged, and the output of the NOT gate N2 becomes L level, thus no reset signal is generated as shown at the left part of Figure (4). In thetimer circuit 9, the latch Lt2 formed by the NOR gates NR3, NR4 has the input of L level, and accordingly its output, too, is at L level as shown in the left part of Figure (5), thus no clock signal is generated. As shown in Figures (6), (7), the Q outputs of the monostable multivibrators MM1, MM2 are at L level, the Q output of the former MM1 is at H level, and the outputs of the AND gates A2, A3 are at L level. Therefore, the transistors T1, T2 in the operatinglevel changeover circuit 10 do not switch on, and as shown with the dotted line in Figure (11) the operating level of the comparator CM in thecomparison part 3 is at fire level L3 which is determined by dividing ratio of the resistance values of the resistors r1 are r2+r3+r4. The light emitting element LE emits light through the driving circuit PD in thelight emitting part 1 each time the pulse oscillator PO1 generates the synchronizing signal as shown in Figure (10). With the scattered light from the inner wall of the labyrinth the output amplifier AM of the light receiving element SB in thelight receiving part 2 gives off an output as shown in Figure (11). Nevertheless, since this output is below the fire level L3 under the condition without smoke, the comparator CM in thecomparison part 3 has no output as shown in the left part of Figure (12). In thefire discriminating part 4 the output of the NOT gate N3 is at H level because the Q output of the monostable multivibrator MM2 in thetimer circuit 9 is at L level. However, since the output of the comparator CM is at L level, the output of the AND gate A1 becomes L level, and accordingly the input of the latch Lt1 formed by NOR gates NR1, NR2 and the output of the NOR gate NR2 are at L level as shown in the left part of Figure (13). In the smoke detecting functiondiscriminating circuit 11 the output of the comparator CM in thecomparison part 3 being at L level, the outputs of the AND gates A4, As are at L level. Accordingly the output of the OR gate R1 is at L level and the Q output of the R - S flip-flop circuit FF1 is at L level as shown in Figure (14). The Q output of the monostable multivibrator MM2 in thetime circuit 9 is at L level while the output of the NOT gate N4 is at H level. Accordingly, the outputs of the NOR gate NR5 serving as clock signal generator, the Q output of the D-type flip-flop circuit FF2 and the output of the latch Lt3 formed by NOR gate NR6, NR7 are at L level as shown in Figure (16), (15) and (17) respectively. Therefore, in thesignal generating circuit 5 the pulse oscillator P02 produces pulses with frequencies f1 and f2 shown in Figure (18) and (19) respectively. With the pulse having frequency f1 and the Q output of the circuit FF2 being at L level, the output of the NAND gate NA1 becomes continuous H level. With the pulse signal having frequency f2 and the continued H level output of the NAND gate NA1, the NAND gate NA2 generates a pulse signal with a phase opposite to that of the pulse signal having frequency f2 from the pulse oscillator P02 as shown in Figure (20). Since the output of the NOR gate NR5 in thesignal transmission circuit 6 is at H level, the output of the NOR gate NR9 is at L level as shown in the left part of Figure (21), consequently the transistor T3 does not become conductive, and no output appears on thelines - When smoke generated by fire enters the labyrinth and its density exceeds the fire level L3 as shown in the middle part of Figure (1), the amplifier AM for the light receiving element SB generates a pulse signals exceeding the fire level L3 as shown in Figure (11), and the comparator CM generates a corresponding pulse signal as shown in Figure (12) at the time of light emission from the light emitting element LE. With this pulse signal, the synchronizing signal generated by oscillator PO1 as shown in Figure (10) and the H level output of the NOT gate N3, the AND gate A1 generates a pulse signal corresponding to the output of the comparator CM. This pulse signal sets the output of the latch Lt2 formed by NOR gates NR1, NR2 as shown in Figure (13), and the NOR gate NR2 generates a fire detecting output. With the fire detecting output from the NOR gate NR1, the output of the NOR gate NRe in the
signal transmission circuit 6 becomes L level. With this L level output and the pulse signal of frequency f2 from the NAND gate N2 in thesignal generating circuit 5 as shown in Figure (20), the NOR gate NR9 generates a pulse signal with frequency f2 as shown in Figure (21) and sends an abnormal signal with frequency f2 as fire signal as shown in Figure (2) to thelines lines signal receiving circuit 7 in the detector stops conducting, and the signal P2 as shown in Figure 3 (3) is generated in the output line d in thecircuit 7, As a result of this, the output of the NOT gate N1 in the resetsignal generating circuit 8 becomes L level, and the charge on the capacitor C3 is released through the NOT gate N1. When the input of the NOT gate N2 becomes L level, the NOT gate N2 generates the clear signal c as shown in Figure (4). On the other hand, if the output P2 of thecircuit 7 is received by the input terminal of the latch Lt2 formed by NOR gates NR3, NR4 in thetimer circuit 9 before the NOT gate N2 generates the clear signal, the latch Lt2 is set and the NOR gate NR4 gives an output at H level as shown in Figure (5). With the output of the NOR gate NR4 the capacitor C4 is charged as shown with the dotted line in Figure (5) through the resistor r13. Since thecircuit 8 generates the clear signal c as shown in Figure (4) before the capacitor voltage reaches such a level as may be judged as a clock signal, the setting of the latch Lt2 is cleared by this signal c and the charge on the capacitor C4 is released through the resistor r14, thus no clock signal is generated. When resetting the detector in the above manner, if the smoke density is below the fire level L3 as shown in Figure (1), setting of the latch Lt1 formed by NOR gates NR1, NR2 is cleared by the clear signal c shown in Figure (4), and the fire detecting output of the NOR gate NR2 stops as shonw in Figure (13). Then the output of the NOR gate NRb in thesignal transmission circuit 6 becames H level, and the output of the NOR gate NR9 stops, thus no fire signal is sent to thelines 11, L2. Consequently, the abnormal signal detecting circuit M in the control panel shown in Figure 2 no longer detects the fire signal, thus the contact mi opens, and the fire indicator lamp Lai extinguishes. - Operation of each part at the time of testing while the output of the amplifier AM in the
light receiving part 2 is within the normal level range is described below with reference to the time chart shown in Figure 4 (A). - As the test start switch SW1 in the control panel shown in Figure 2 is closed, the relay X operates and the contacts x1 ~ x3 close.
- The test start signal generator TS sends the test start signal shown with a symbol P1 in Figure 4A (2) to the
lines signal receiving circuit 7 of the detector shown in Figure 1. Thecircuit 7 generates the pulse signal Pi' in the output line d as shown in Figure (3). With the signal P1', the output of the NOT gate N1 in the resetsignal generating circuit 8 becomes L level, and the charge on the capacitor C3 is released through the NOT gate N1. Nevertheless, before the voltage of the capacitor C3 raises the output of the NOT gate N2 to H level, the output P1' disappears and the output of the NOT gate N1 again becomes H level. Therefore, the capacitor C3 is recharged, thus the NOT gate N2 maintains the L level output as shown in Figure (4). The output P1' of thecircuit 7 also sets the latch Lt2 formed by NOR gates NR3, NR4 in the timer circuit 9: As the capacitor C4 is charged with the H level output of the NOR gate NR4 through the resistor r13 as shown with the dotted line in Figure (5) and its voltage reaches the H level, the clock signal is sent to the CP terminals of the monostable multivibrators MM1, MM2 with this voltage. At the Q terminals of the monostable multivibrators MM1, MM2, H level outputs develop as shown in Figures (6), (7), and a L level output develops on the Q terminal of the monostable multivibrator MM1, then the output of the AND gate A2 becomes H level as shown in Figure (8). The transistor T1 in the operatinglevel changeover circuit 10 too is conducting while the output of the AND gate A2 is at H level. Thus, the operating level of the comparator CM in thecomparison part 3 becomes the lower level L1 of the normal level range which is determined by resistance dividing ratio of the resistor r1, r2, as shown with the dotted line in Figure (11). Furthermore, since the Q output of the monostable multivibrator MMz is at H level, the output of the NOT gate N3 becomes L level and inhibits operation of the AND gate Ai. On the other hand the capacitor C3 in thefunction discriminating circuit 11 is charged. When its voltage reaches a predetermined value, the output of the NOT gate N4 becomes L level, but the other input of the NOR gate NRs is at H level. Therefore, the NOR gate NR5 does not produce the clock signal. - Under this condition, if the pulse output of the amplifier AM in the
signal receiving part 2 lies between the lower level L1 and the upper level L2 of the normal level range as shown in Figure (11), the comparator CM generates detecting pulse signal as shown in Figure (12) because the pulse output of the amplifier AM is above the operating level of the comparator CM. With this pulse output of the comparator CM, synchronized signal generated by the pulse oscillator PO1 and H level output of the AND gate A2, the AND gate A4 generates the pulse output similar to that of the comparator CM as shown in Figure (12). This output of the AND gate A4 sets the Q output of the circuit FF1 in thefunction discriminating circuit 11 at H level as shown in Figure (14). On the other hand the Q output of the circuit FF2 remains at L level as shown in Figure (15) because the CP terminal receives no clock signal from the NOR gate NRs. - After lapse of a predetermined short time the Q output and Q output of the monostable multivibrator MM1 in the
timer circuit 9 become L level and H level respectively as shown in Figure (6). Consequently, the output of the AND gate A2 becomes L level as shown in Figure (8), inhibiting operation of the AND gate A4 in thecircuit 11, and rendering the transistor T1 in thecircuit 10 non conductive. On the other hand, the output of the AND gate A3 becomes H level as shown in Figure (9), the transistor T2 becomes conductive, and the operating level of the comparator CM in thecomparison part 3 reaches the upper level of the normal level range as shown with the symbol L2 in Figure (11) which is determined by dividing ratio of the resistors r1 and r2+r3. Under this condition, if the amplifier AM in thelight receiving part 2 has the normal output as shown in Figure (11), the output of the comparator CM is at L level as shown in Figure (12) because the output of the amplifier AM is below the level L2. - When the output of the monostable multivibrator MM2 becomes L level as shown in Figure (7) after lapse of a predetermined long time, this L level output and the output of the NOT gate N4 in the
function discriminating circuit 11 at L level cause the NOR gate NR5 to generate the clock signal c as shown in Figure (16). With this signal c, the Q output of the flip-flop circuit FF2 becomes H level as shown in Figure (-15) because the Q output of the flip-flop circuit FF1 is at H level as shown in Figure (14). With the H level output of the flip-flop circuit FF2, the NAND gate NA1 in thesignal generating circuit 5 generates a pulse signal having the phase opposite to that of the pulse signal with frequency f1 generated by the oscillator P02, :and the NAND gate NA2 generates a pulse signal with frequency f1 as shown in Figure (20). The clock signal from the NOR gate NR5 sets the latch Lt3 formed by NOR gates NR6, NR7, and the output of the NOR gate NR7 becomes H level. With this H level output, the output of the NOR gate NR6 in thesignal transmission circuit 6 becomes L level, and the NOR gate NR9 generates a pulse signal with frequency f1 as shown in Figure (21), by which conduction of the transistor T3 is controlled and the normal signal shown in Figure (2) is sent to the lines l1, l2. Lastly, as thesignal receiving circuit 7 has received the reset signal P2 shown in Figure (2) and has an output P2' shown in Figure (3) on its output line d, the NOT gate N2 in the resetsignal generating circuit 8 generates a clear signal c shown in Figure (4), which resets the latches Lt2, Lt3 formed by NOR gates NR3, NR4 and NR6, NR7 respectivel in the same manner as resetting in case of fire. Then, the outputs of the NOR gates NR4, NR7 become L level as shown in Figure (5) and (17) respectively. With the L level output of the NOR gate NR7, the NOR gate NR9 no longer generates the pulse signal as shown in Figure (21), and accordingly thesignal transmission circuit 6 stops transmitting the normal signal as shown in Figure (2). The clear signal from the NOT gate N2 resets the flip-flop circuit FF1 in thefunction discriminatin circuit 11 through the OR gate R1, and the flip-flop circuit FF2 directly. The Q outputs of the beth circuits become L level as shown in Figures (14), (15). With the L level output of the flip-flop circuit FF2, the output of the NAND gate NA1 in thesignal generating circuit 5 become H level and the NOT gate NA2 generates the pulse signal with frequency f2 as shown in Figure (20), thus each part of the detector returns to the original state. - Now, the following describes operation of each part during the test with reference to the time chart shown in Figure 5 (A) in case that the output of the amplifier AM has been reduced below the lower level L1 of the normal level range due to soiling by dust accumulating over the light receiving surface of the light receiving element SB in the
light receiving part 2. - In this case, too, the
signal receiving circuit 7 in Figure 1 generates a pulse signal P1' in the output line d with the test start signal P1 from the control panel shown in Figure 5 (A) (2). However, due to -narrow pulse width of the pulse signal P1', the NOT gate N2 in the resetsignal generating circuit 8 generates no clear signal. On the other hand the latch Lt2 formed by NOR gates NR3, NR4 in thetimer circuit 9 is set as shown in Figure (5) with the pulse signal P1'. When the capacitor C4 is charged with the H level output of the NOR gate NR4 through the resistor r13 as shown with the dotted line in Figure 5 (A) (5) and the voltage reaches the H level, outputs of H level develop at the Q terminals of the monostable multivibrators MM1, MM2 as shown in Figure (6), (7), and the output of the AND gate A2 becomes H level. Then, the transistor T1 in the operatinglevel changeover circuit 10 becomes conductive as shown in Figure (8), and the operating level of the comparator CM in thecomparison part 3 becomes the lower level L1 of the normal level range as shown with the dotted line in Figure (11). - With the H level output of the monostable multivibrator MM2, the output of the NOT gate N3 in the
fire discriminating part 4 becomes L level and inhibits operation of the AND gate Al, while on the other hand the NOR gate NR5 in thefunction discriminating circuit 11 generates no clock signal as shown in Figure (16). - Under this condition, if the output of the amplifier AM in the
light receiving part 2 is below the level L1 as shown in Figure (11), the transistor T1 in the operatinglevel changeover circuit 10 becomes conductive as shown in Figure (8). Therefore, even if the operating level of the comparator CM in thecomparison part 3 becomes the lower level L1 as shown in Figure (11), no detecting signal is generated in the comparator CM as shown in Figure (12), the AND gate A4 in thefunction discriminating circuit 11 has no output, and the flip-flop circuit FF1 is not set as shown in Figure (14). - Then, after lapse of a predetermined time, the Q output of the monostable multivibrator MM1 in the
timer circuit 9 becomes L level as shown in Figure 6, and the Q output becomes H level. The outputs of the AND gates A2, A3 become L and H levels respectively as shown in Figures (8), (9), thus rendering the transistor T1 non-conductive and the transistor T2 conductive. Consequently the operating level of the comparator CM becomes the level L2 as shown in Figure (11). Enen at this level L2, the comparator CM has no output as shown in Figure (12), and the AND gate A,, too, has no output. After further lapse of a predetermined time the Q output of the monostable multivibrator MM2 becomes L level as shown in Figure (7), and the NOR gate NRs generates the clock signal c shown in Figure (16), which sets the latch Lt3. - As the output of the NOR gate NRa in the
signal transmission circuit 6 becomes L level with the H level output of the NOR gate NR7 shown in Figure (17), the NOR gate NR, generates a pulse signal with frequency f2 as shown in Figure (21) because the NAND gate NA2 in thesignal generating circuit 5 is generating a pulse signal with frequency f2 as shown in Figure (20). By the pulse signal from the NOR gate NR9, conduction of the transistor T3 is controlled, and the abnormal signal is sent to the control panel through thelines - The following describes operation of each part during the test with reference to the time chart shown in Figure 6 (A), which is carried out in case the output of the amplifier AM for the light receiving element SB in the
light receiving part 2 has exceeded the upper level L2 of the normal level range due to accumulation of dust in the labyrinth. As in the case of the foregoing, thesignal receiving circuit 7 in Figure 1 generates the pulse signal P1' in the output line d shown in Figure (3) with the test start signal P1 from the control panel shown in Figure 6 (A) (2). Although the NOT gate N2 in the resetsignal generating circuit 8 does not generate the clear signal, the latch Lt2 in thetimer circuit 9 is set. The capacitor C4 is charged with the H level output of the NOR gate NR4 as shown with the dotted line in Figure (5). When the voltage reaches the H level, outputs of H level develop at the Q terminals of the monostable multivibrators MMi, MM2 as shown in Figure (6), (7) and the output of the AND gate A2 becomes H level. Then, the transistor T1 in the operatinglevel changeover circuit 10 becomes conductive as shown in Figure 6 (8), and the operating level of the comparator CM in thecomparison part 3 becomes the lower level L1 of the normal level range as shown with the dotted line in Figure (11). With the H level output of the Q terminal of the monostable multivibrator MM2, the output of the NOT gate N3 in thefire discriminating circuit 4 becomes L level and-inhibits operation of the AND gate A1, while-on the other hand the NOR gate NR5 in thefunction discriminating circuit 11 generates no clock signal. - Under this condition, if the output of the amplifier AM in the
light receiving part 2 is over the level L2 as shown in Figure (11), the transistor T1 in the operatinglevel changeover circuit 10 become conductive as shown in Figure (8). As the operating level of the comparator CM in thecomparison part 3 becomes the level L1 as shown in Figure (11), the output of the comparator CM becomes the H level. With this output of the comparator CM, the output of the AND gate A4 in thefunction discriminating circuit 11 becomes H level, and accordingly the Q output of the flip-flop circuit FF1 is set at H level as shown in Figure (14). However, since the CP terminal of the flip-flop circuit FF2 receives no clock signal from the NOR gate NR5, the Q output of the flip-flop circuit remains at L level. After lapse of a predetermined time under this condition, the Q output of the monostable multivibrator MM1 in thetimer circuit 9 becomes L level as shonw in Figure (6) and Q output becomes H level. The outputs of the AND gates A2, As become L and H levels respectively as shown in Figure (8), (9). Thus, the transistor T1 becomes non-conductive and the transistor T2 conductive. Then, the operating level of the comparator CM changes to level L2 as shown in Figure (11), the output of the comparator CM remains at II level. With this output the AND gate A5 and the OR gate R1 generate H level outputs successively. With the output reaching the reset terminal R of the flip-flop circuit FF1, the Q output of the flip-flop circuit FF1 is reset at the L level as shown in Figure (14). Even if the comparator CM has an output thereafter, the Q output of the flip-flop circuit FF1 remains at L level as shown in Figure (14) as long as the operating level of the comparator CM is at the level L2, because the output of the comparator CM reaches the R terminal of the flip-flop circuit FF1 through the AND gate As and the OR gate Rl. As in the previous case, after lapse of a predetermined time the Q output of the monostable multivibrator MM2 becomes L level as shown in Figure (7), and the NOR gate NR5 in thecircuit 11 generates the clock signal c shown in Figure (16), which sets the latch Lt3. As the NOR gate NR7 has H level output shown in Figure (17), and the output of the NOR gate NRs in thesignal transmission circuit 6 becomes the L level, the NAND gate NA2 in thesignal generating circuit 5 generates a pulse signal with frequency f2 as shown in Figure (20), and accordingly the NOR gate NR9 generates a pulse signal of frequency f2 as shown in Figure (21) to control conduction of the transistor T3 and to send an abnormal signal to the control panel through thelines - Now, the following describes how the
signal receiving circuit 7 operates with the reset signal P2 shown in Figure 5 (A) and 6 (A) (2) and received from the control panel after the test conducted in case that the output of the amplifier AM has fallen below the lower level L1 and exceeded the upper level L2. Thesignal receiving circuit 7 generates a pulse signal P2' shown in Figure (3) in the output line d. The NOT gate N2 in the resetsignal generating circuit 8 generates the clear signal c shown in Figure 6 (4), with which the latches Lt2, Lt3 formed by NOR gates NR3, NR4 and NR6, NR7 respectively are reset. Then, the outputs of the NOR gates NR4, NR7 become L level as shown in Figures (5) and (17). Because of this L level output of the NOR gate NR7, the NOR gate NR9 no longer generates the pulse signal as shown in Figure (21), and thesignal transmission circuit 6 stops transmitting the abnormal signal to thelines - Lastly, the following describes operation of the control panel when the test is conducted with the test start signal from the control panel shown in Figure 2. When the switch SW1 is closed for testing, the relay X operates tu close the contacts x1 ~ x3 and open the contact x4. Therefore, on receipt of the normal signal from the detector shown in Figure 1, the relay N operates and close the contact N1, and the normal indicator lamp La3 lights. When the abnormal signal is received, the relay M operates and closes the contacts ml, m2 to cause the abnormal indicator lamp La2 to light up indicating that there is abnormality in the smoke detecting function. As the switch SW2 is closed to reset the detector, the relay Y operates and closes the contact y1 and opens the contact y2 to actuate the reset signal generator RS which sends the reset signal to the
lines - The light extinction type smoke detector shown in Figure 7 only differs from Figure 1 in that the resistors r1 ~ r4 are connected in series across the conductors a, b in opposite order to determine the upper level L1 of the normal level range as threshold level at which alarm failure or delayed alarm is likely to occur, a lower level L2 as threshold level at which false alarm is likely to be produced, and the fire level Ls, and that the voltage of operating level developing at the junction of the resistors r1 and r2 is applied to the + terminal of the comparator CM in the
comparison part 3 and the output of the amplifier AM in thelight receiving part 2 is led to the - terminal so that the comparator CM generates the detecting output -when the output of the amplifier AM has fallen below the operating level. Therefore, as compared with the time chart of Figure 3 (A) of the embodiment shown in Figure 1, the normal supervisory state of this embodiment and the operating state of each part in case of fire only differs in the outputs of the amplifier AM in thelight receiving part 2 and of the comparator CM in thecomparison part 3 as shown in Figures (11) and (12). Therefore, these different outputs shown with Figures (11), (12) are extracted and indicated at the lower part of Figure 3 (A) as Figures (B) (11'), (12'). - Now, operation of the embodiment is described with reference to Figures 3 (A) but (11), (12), and (B) (11'), (12'). With respect to Figure 3 (A) some descriptions have already been made, and only their summary is given hereunder. In normal supervisory condition without smoke the transistor T1 in the
signal receiving circuit 7 is conducting and its output line d has no output as shown in the left part of Figure (3). - Consequently, the outputs of the reset
signal generating circuit 8 and of the AND gates A2, As in thetimer circuit 9 are L level, and the transistors T1, T2 in the operatinglevel changeover circuit 10 do not conduct. As the operating level of the comparator CM in thecomparison part 3 is at the fire level L3 (e.g. 85X light transmittivity of the output of the amplifier AM as indication of light transmittivity while no smoke presents), the comparator CM has the L level output shown in Figure (12') and the output of the AND gate A1 is at the L level when the amplifier AM generates a pulse signal exceeding the level L3 shown in Figure (11'). Consequently, no signal is sent to thelines light emitting part 1 and the light receiving element SB in thelight receiving part 2, the comparator CM has the H level output as shown in Figure (12'), with which and the synchronizing signal from the oscillator PO1 and the H level output of the NOT gate Ns, the AND gate A1 in thefire detecting part 4 generates a pulse signal corresponding to the output of the comparator CM. Then, the latch Lt1 formed by the NOR gates NRi, NR2 is set as shown in Figure (13). With the H level output of the NOR gate NR2, a fire signal with frequency f2 shown in Figure (2) is sent to thelines signal transmission circuit 6. Operation of the control panel after receipt of this fire signal and resetting of the fire detector by reset signal from the control panel are same as in the case of the light scattering type smoke detector. - Operation of each part at the time of the test while the output of the amplifier AM in the
light receiving part 2 of this embodiment only differs in Figure (11) showing the output of the amplifier AM in thelight receiving part 2 and Figure (12) showing the output of the comparator CM in thecomparison part 3 as compared with the time chart, Figure 4 (A) for the embodiment shown in Figure 1. Therefore, only these different outputs shown with Figures (11), (12) are extracted and indicated at the lower part of Figure 4 (A) as Figure (B) (II'), (12'). - Now, operation of the embodiments is described with reference to Figures 4 (A) but (11), (12), and (B) (II'), (12'). With the test start signal P1 shown in Figure (2) from the control panel the
signal receiving circuit 7 generates a pulse output P1,' shown in Figure (3) in its output line d, but the resetsignal generating circuit 8 does not generate the clear signal due to the narrow pulse width. The pulse signal P1' sets the latch Lt2 formed by NOR gates NR,, NR4 in thetimer circuit 9. With the H level output of the NOR gate NR4 shown in Figure (5) the capacitor C4 is charged as shown with the dotted line in Figure (5). As the voltage of the capacitor C4 reaches the H level, the clock signal is transmitted to the CP terminals of the monostable multivibrators MM1, MM2. Then, the Q terminals of the monostable multivibrators MM1, MM2 have H level outputs as shown in Figures (6), (7), with which the output of the AND gate A2, too, become the H level as shown in Figure (8), and the transistor T1 in the operatinglevel changeover circuit 10 becomes conductive. The operating level of the comparator CM in thecomparison part 3 becomes the upper level L1 of the normal-level range (e.g. 105% light transmittivity) as shown with the dotted line in Figure (11'). Under this condition, if the pulse output of the amplifier AM in thelight receiving part 2 lies between the upper level L1 and the lower level L2 of the normal level range as shown in Figure (11'), the pulse output is below the operating level of the comparator CM. Therefore, the comparator CM has no L level output, but H level output as shown in Figure (12'). With this H level output and the synchronizing signal from the oscillator PO1 and the H level output of the AND gate A2, the AND gate A4 generates a pulse output which is similar to that shown in Figure (12). By this pulse signal the output of the Q terminal of the flip-flop circuit FF1 in thefunction discriminating circuit 11 is set at H level. However, since no clock signal is transmitted from the NOR gate NR5 to the CP terminal of the flip-flop circuit FF2, the output of the Q terminal remains at L level as shown in Figure (15): After lapse of a predetermined time the output of the Q terminal of the monostable multivibrator MM1 in thetimer circuit 9 becomesL level as shown in Figure (6), and the output of the Q terminal becomesH level. The outputs of the AND gates A2 and As become L and H levels respectively as shown in Figures(8) and (9). In the operatinglevel changeover circuit 10, the transistor T1 stops conducting and the transistor T2 become conductive, thus the operating level of the comparator CM in thecomparison part 3 becomes the lower level L2 of the normal level range. Under this condition, the output of the amplifier AM in thelight receiving part 2, if generated, is above the level L2, and therefore the output of the comparator CM becomes the L level as shown in Figure (12'). When the output of the monostable multivibrator MM2 in thetimer circuit 9 become L level as shown in Figure (7) after lapse of a predetermined time, this L level output and the L level output of the NOT gate N4 in thefunction discriminating circuit 11 cause the NOR gate NR5 to generate the clock signal c as shown in Figure (16). With this signal c the flip-flop circuit FF2 has the H level output shown in Figure (15) at the Q terminal. With this H level output and the H level output shown in Figure (17) of the NOR gate NR7 of the latch Lt3 which is set by the clock signal c, the normal signal shown in Figure (2) is sent to thelines signal generating circuit 5 and thesignal transmission circuit 6. As thesignal receiving circuit 7 receives from the control panel the reset signal P2 shown in Figure (2), each part of the fire detector returns to its original state in the same manner as the light scattering type smoke detector. - Operation of each part at the time of the test in case the output of the light receiving element SB in the
light receiving element 2 has increased due to influence of the external light and the output of the amplifier AM has exceeded the upper level L1 of the normal level range only differs in Figure (11) showing the output of the amplifier AM and Figure (12) showing the output of the comparator CM in thecomparison part 3 as compared with the time chart, Figure 5 (A) for the embodiment shown in Figure 1. Therefore, only these different outputs shown in Figures (11), (12) are extracted and indicated at the lower part of Figure 5 (A) as Figure (B) (11'), (12'). - Now, operation of the embodiment is described with reference to Figure 5 (A) but (11), (12), and to Figures (B) (II'), (12'). With the test start signal P1 shown in Figure (2) the
signal receiving circuit 7 generates a pulse output Pl' shown in Figure (3) in its output line d, but the resetsignal generating circuit 8 does not generate a clear signal due to the narrow pulse width. The pulse signal P1' sets the latch Ltz formed by NOR gates NR3, NR4 in thetimer circuit 9. With the H level output of the NOR gate NR4 shown in Figure (5), the H level outputs shown in Figures (6), (7) appear on the Q terminals of the monostable multivibrators MM1, MM2, and the output of the AND gate A2 becomes H level, and the transistor T1 in the operatinglevel changeover circuit 10 becomes conductive as shown in Figure (8). Thus, the operating level of the comparator CM becomes the upper level L1 of the normal level range as shown with the dotted line in Figure (11'). Under this condition, if the output of the amplifier AM in thelight receiving part 2 is above the upper level L1, the comparator CM in thecomparison part 3 has no output as shown in Figure (12'), and the transistors T1, T2 in the operatinglevel changeover circuit 10 become conductive as shown in Figures (8), (9). Therefore, even if the operating level of the comparator CM has changed from the level L1 to the level L2, the comparator CM has no output. After lapse of a predetermined time the output of the Q terminal of the monostable multivibrator MM2 becomes L level as shown in Figure (7). The NOR gate NR5 in the smoke detectingfunction discriminating circuit 11 generates the clock signal c shown in Figure (16), and the NOR gate NR7 has the H level output as shown in -Figure (17). The output of the NOR gate NRe in thesignal transmission circuit 6 becomes L level. Then, the NOR gate NR9 generates a pulse output with frequency f2 as shown in Figure (21) to send the abnormal signal to thelines 11, lz as shown in Figure (2). - Operation of each part at the time of the test in case the output of the amplifier AM has fallen below the lower level L2 of the normal level range due to soiling of the light receiving surface of the light receiving element SB in the
light receiving part 2 by dust only differs in Figure (11) showing the output of the amplifier AM and Figure (12) showing the output of the comparator CM as compared with the time chart, Figure 6 (A) for the embodiment shown in Figure 1. Therefore, only these different outputs shown in Figures (11), (12) are extracted and indicated at the lower part of Figure 6 (A) as Figures(B) (11'), (12'). - Now, operation of the embodiment is described with reference to Figure 6 (A) but (11), (12), and to Figures (B) (11'), (12'). With the test start signal P1 shown in Figure (2) the
signal receiving circuit 7 generates a pulse output P1' with narrow width shown in Figure (3) in its output line d, but the resetsignal generating circuit 8 does not generate a clear signal. The latch Ltz formed by NOR gates NR3, NR4 is set. With the H level output of the NOR gate NR4 shown in Figure (5) the H level outputs shown in Figures (6), (7) appear on the Q terminals of the monostable multivibrators MM1, MM2, and the output of the AND gate A2 becomes H level, and the transistor T1 in the operatinglevel changeover circuit 10 becomes conductive as shown in Figure (8). Thus, the operating level of the comparator CM becomes the upper level L4 of the normal level range as shown with the dotted line in Figure (11'). If the output of the amplifier AM in thelight receiving part 2 is below the lower level L2 of the normal level range at this time, the comparator CM has no L level output but the H level output as shown in Figure (12'). With this H level output the AND gate A4 in thefunction discriminating circuit 11 generates a pulse output similar to that shown in Figure (12). - This pulse output sets the output of the Q terminal of the flip-flop circuit at H level as shown in Figure (14), but the output of the Q terminal of the flip-flop circuit FF2 remains at L level because no clock signal is transmitted to the CP terminal of the flip-flop circuit FF2. Under this condition, the transistor T2 soon becomes conductive in place of the transistor T1 as shown in Figure (9), and the operating level of the comparator CM changes to the level L2 as shown in Figure (11'). In this case, too, the output of the comparator CM is at H level, with which the AND gate A5 and OR gate R1 successively generate H level outputs to the R terminal of the flip-flop circuit FF1, the Q output of which becomes the L level as shown in Figure (14). After lapse of a predetermined time as the output of the Q terminal of the monostable multivibrator MM2 becomes L level as shown in Figure (7), and the NOR gate NR5 in the
function discriminating circuit 11 generates the clock signal c as shown in Figure (16), the latch Lt3 formed by NOR gates NR6, NR7 is set. Then, the NOR gate NR7 has a H level output as shown in Figure (17), and the abnormal signal is transmitted to the control panel through thesignal transmission circuit 6 and thelines - Operation of the smoke detector when its
signal receiving circuit 7 has received the reset signal P2 from the control panel after the test in case the output of the amplifier AM exceeded the upper level L1 of the normal level range and fallen below the lower level L2, and operation of the control panel when tested with the test start signal from the control panel are same as in the case of the light scattering type smoke detector. - In the both cases of the light scattering type and light extinction type smoke detectors, if there is a trouble in the detector circuit or interruption of the
lines lines - In the above embodiments, the descriptions are made with respect to such cases that the smoke detector and the control panel are connected by two lines which are commonly used as power supply lines and signal lines. However, in Figures 1 and 7 the terminal on the right side of the voltage stabilizing circuit CV may be disconnected from the
line 11 and connected with athird line 13 which is exclusively used for power supply so that the power supply lines may be separated from the signal lines to avoid influence of the pulse signal width upon the voltage stabilizing circuit and to get a larger S/N ratio. - As can be seen from the above description, the photoelectric type smoke detector equipped with smoke detecting function test means according to this invention has such as advantage that with proper composition it is capable of automatically, readily and precisely checking, on the basis of the signal sent from the control panel through the lines connecting the smoke detector with the control panel, whether the output of the detector is within the normal level range which cause no false alarm, alarm failure nor delayed alarm, i.e. an important function of this type of detector, and of reporting to the control panel on results of the test through the same lines.
- Figures 1 and 7 are circuit diagrams of embodiments of the light scattering type and light extinction type smoke detectors equipped with smoke detecting function test means according to this invention. Figure 2 is a circuit diagram of a control panel which is common to these two embodiments. Figures 3 through 6 are time charts showing operating status of each part of the embodiments shown with Figures 1 and 7 in different casses, i.e. Figure 3 (A) is the one for the embodiment of Figure 1 in normal condition and in case of fire, Figure 4 (A) is the one at the time of test while the output of the embodiment shown in Figure 1 is within the normal level range, and Figures 5 (A) and 6 (A) are the ones at the time of tests in the cases that the output of the embodiment shown in Figure 1 is below the lower limit and above the upper limit of the normal level-range. Figures 3 (B) through 6 (B) shown only outputs (11') and (12') of amplifier AM and comparator CM respectively which differ from those shown in Figures 3 (A) through 6 (A) in the time charts corresponding to Figures 3 (A) through 6 (A) of the embodiment shown with Figure 7.
- 1 .................. Light emitting part
- 2 .................. Light receiving part
- 3 .................. Comparison part
- 4 .................. Fire discriminating part
- 5 .................. Signal generating part
- 6 .................. Signal transmission circuit
- 7 .................. Signal receiving circuit
- 8 .................. Reset signal generating circuit
- 9 .................. Timer circuit
- 10 .................. Operating level changeover circuit
- 11 .................. Smoke detecting function discriminating circuit
Claims (3)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP4668383A JPS59172094A (en) | 1983-03-21 | 1983-03-21 | Optoelectric smoke sensor with smoke detecting function tester |
JP46683/83 | 1983-03-21 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0122432A1 true EP0122432A1 (en) | 1984-10-24 |
EP0122432B1 EP0122432B1 (en) | 1987-12-23 |
Family
ID=12754171
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19840102465 Expired EP0122432B1 (en) | 1983-03-21 | 1984-03-08 | Photoelectric smoke detector equipped with smoke detecting function test means |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0122432B1 (en) |
JP (1) | JPS59172094A (en) |
DE (1) | DE3468286D1 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0213383A1 (en) * | 1985-07-29 | 1987-03-11 | Siemens Aktiengesellschaft | Method and device for monitoring the operation of optical smoke detectors |
GB2293877A (en) * | 1994-09-27 | 1996-04-10 | Hochiki Co | Projected beam type smoke detector and receiving unit |
GB2326474A (en) * | 1994-09-27 | 1998-12-23 | Hochiki Co | Projected beam type smoke detector and receiving unit |
WO2004034348A1 (en) * | 2002-10-04 | 2004-04-22 | Valery Vasilievich Ovchinnikov | Method for forming and transmitting signals |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4306230A (en) * | 1979-12-10 | 1981-12-15 | Honeywell Inc. | Self-checking photoelectric smoke detector |
EP0067339A2 (en) * | 1981-06-12 | 1982-12-22 | Siemens Aktiengesellschaft | Method and arrangement for disturbance detection in hazard signalling systems, especially fire signalling systems |
US4374329A (en) * | 1981-04-24 | 1983-02-15 | Pittway Corporation | Smoke detector with test apparatus |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5612707Y2 (en) * | 1972-09-16 | 1981-03-24 | ||
JPS507583A (en) * | 1973-05-17 | 1975-01-25 | ||
JPS5377199A (en) * | 1976-12-20 | 1978-07-08 | Matsushita Electric Ind Co Ltd | Fire detector |
JPS57102873U (en) * | 1980-12-15 | 1982-06-24 | ||
JPS57172495A (en) * | 1981-04-15 | 1982-10-23 | Nittan Co Ltd | Select test circuit for fire sensor, etc. |
-
1983
- 1983-03-21 JP JP4668383A patent/JPS59172094A/en active Granted
-
1984
- 1984-03-08 EP EP19840102465 patent/EP0122432B1/en not_active Expired
- 1984-03-08 DE DE8484102465T patent/DE3468286D1/en not_active Expired
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4306230A (en) * | 1979-12-10 | 1981-12-15 | Honeywell Inc. | Self-checking photoelectric smoke detector |
US4374329A (en) * | 1981-04-24 | 1983-02-15 | Pittway Corporation | Smoke detector with test apparatus |
EP0067339A2 (en) * | 1981-06-12 | 1982-12-22 | Siemens Aktiengesellschaft | Method and arrangement for disturbance detection in hazard signalling systems, especially fire signalling systems |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0213383A1 (en) * | 1985-07-29 | 1987-03-11 | Siemens Aktiengesellschaft | Method and device for monitoring the operation of optical smoke detectors |
GB2293877A (en) * | 1994-09-27 | 1996-04-10 | Hochiki Co | Projected beam type smoke detector and receiving unit |
GB2326474A (en) * | 1994-09-27 | 1998-12-23 | Hochiki Co | Projected beam type smoke detector and receiving unit |
GB2293877B (en) * | 1994-09-27 | 1999-03-24 | Hochiki Co | Projected beam-type smoke detector and receiving unit |
WO2004034348A1 (en) * | 2002-10-04 | 2004-04-22 | Valery Vasilievich Ovchinnikov | Method for forming and transmitting signals |
CN100593179C (en) * | 2002-10-04 | 2010-03-03 | 瓦列里·瓦西里耶维奇·奥夫奇尼科夫 | Method for forming and transmitting signals |
US7522037B2 (en) | 2002-10-10 | 2009-04-21 | Valery Vasilievich Ovchinnikov | Method for forming and transmitting signals |
Also Published As
Publication number | Publication date |
---|---|
JPH0441396B2 (en) | 1992-07-08 |
DE3468286D1 (en) | 1988-02-04 |
JPS59172094A (en) | 1984-09-28 |
EP0122432B1 (en) | 1987-12-23 |
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