JP3822395B2 - Photoelectric smoke detector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photoelectric smoke detector capable of performing a remote test using an externally connected tester, and more particularly to a self-transmitting fire signal that can be remotely tested by two wires and only detects a fire. The present invention relates to a recovery type photoelectric smoke detector.
[0002]
[Prior art]
Conventionally, as a photoelectric smoke detector capable of remote testing, for example, a smoke detector disclosed in JP-A-8-171686 is known.
[0003]
This smoke detector is a three-wire type in which an operation test line is separately provided in addition to a signal line and a common line provided as a power-supply signal line. The smoke detector is self-holding. The self-holding smoke detector turns on the thyristor and sends a fire signal once it detects a fire, and keeps sending the fire signal until a recovery operation is performed to shut off the power supply on the receiver side.
[0004]
For this reason, when a plurality of smoke detectors connected to the sensor line are remotely tested in sequence, the sensor is returned to the test with the operation test signal from the tester and then restored, and this is repeated for each sensor. become.
[0005]
The smoke detector disclosed in JP-A-8-171686 has a counter circuit (storage circuit) in which two stages of D-type flip-flops (hereinafter referred to as “D-FF”) are connected, and the main light source LED is intermittently driven by an oscillation pulse. The thyristor emits light and the scattered light generated by the reflection of the light to the smoke particles is received by the light receiving element, and the counter signal is output by two consecutive two counts of the light receiving signal exceeding the predetermined threshold in synchronization with the oscillation pulse. Is turned on and a fire signal is sent out.
[0006]
During a remote test, when a test signal is received from an external tester, the test light source LED is asynchronously driven intermittently with a shorter cycle than the main light source LED by the oscillation pulse of the test oscillation circuit, and the light receiving element is directly irradiated with the test light. As in the case of the main light source LED, a counter signal is output with two consecutive counts of two light reception signals that are equal to or greater than a predetermined threshold in synchronization with the oscillation pulse, the thyristor is turned on, and a fire signal from the test is sent to the tester. The test results are displayed.
[0007]
[Problems to be solved by the invention]
In contrast to the conventional self-holding type smoke detector, a self-recovering type smoke detector is known. The self-healing smoke detector turns on a switching element such as a transistor and sends a fire signal only while a fire is detected. When no fire is detected, the transistor turns off and stops sending the fire signal. To do.
[0008]
However, when a remote test is performed with the test light source LED intermittently emitting light in a short cycle asynchronously with the main light source LED for the self-recovery smoke detector, the counter circuit counts the received light signal by the test light emission, and the main light source At the same time, a reset operation by a lightless signal without smoke synchronized with the light emission is received.
[0009]
For this reason, depending on the timing of test light emission and main light source light emission, the test may not be performed normally. For example, if the counter reset due to light emission of the main light source is applied immediately after the test light emission counter output, the transistor will only turn on for a very short time, and a fire signal exceeding a predetermined time width cannot be obtained by the tester. There is a problem of misjudging it as abnormal.
[0010]
In addition, it is common practice to provide a test light source LED for the smoke detector and irradiate the light receiving element with the test light. In this case, even if the main light source LED fails, a normal test result is obtained. Since it is obtained, it is erroneously determined to be normal.
[0011]
In JP-A-8-171686, the diffusely reflected light in the chamber due to the light emission of the main light source LED is received by the light receiving unit, and the light receiving signal is amplified by the amplifying unit to monitor that it is above the specified level. When an amplified signal cannot be obtained, a function abnormality signal is output to prohibit the test operation.
[0012]
However, the diffusely reflected light in the chamber is extremely weak, and high gain amplification is necessary to amplify to the level necessary for monitoring, and there is a problem that the circuit configuration is complicated and lacks stability.
[0013]
Furthermore, the smoke detector disclosed in JP-A-8-171686 requires a separate operation test line in addition to a signal line and a common line provided as a pair of power supply and signal lines, and is a three-wire type. However, a normal sensor line is a two-wire system, and using a three-wire system for remote testing increases the equipment cost, and a smoke sensor with a remote test function cannot be used for the existing sensor line. There is a need for a smoke detector that can be remotely tested in two wires.
[0014]
The present invention has been made in view of such conventional problems, and an object thereof is to provide a photoelectric smoke detector that can appropriately perform a remote test for a two-wire self-recovery type. .
[0015]
[Means for Solving the Problems]
In order to achieve this object, the present invention is configured as follows. First, the photoelectric sensor of the present invention is a two-wire type and is a self-recovering type. That is, the photoelectric smoke detector according to the present invention includes a main light source emitting unit that intermittently drives the main light source by the oscillation pulse of the main light source oscillation circuit and irradiates light toward the smoke detection space in the chamber, and the main light source A light receiving unit that receives scattered light generated by reflection of light reflected in the smoke in the smoke detection space, and a light reception signal obtained by the light receiving unit is counted when a preset threshold value is exceeded. A counter circuit (storage circuit) that outputs a signal and a self-recovering fire signal output circuit that switches while the counter circuit outputs a signal and sends a fire signal to the outside via a pair of power signal lines .
[0016]
With respect to such a two-wire and self-restoring photoelectric smoke detector, in the present invention, a test instruction is received by receiving a test instruction from an external tester via a pair of power supply signal lines. A remote test interface circuit for outputting, a test light emitting unit for intermittently driving the test light source by an oscillation pulse of a test oscillation circuit that is asynchronous with the main light source oscillation circuit and having a short cycle, and irradiating the test light toward the light receiving unit; The test light emitting unit is operated by the test signal from the test interface circuit, the signal is output from the counter circuit with a predetermined number of counts of the received light signal from the light receiving unit by intermittent driving of the test light source, and the fire signal by the test from the fire signal sending circuit And a test control circuit for sending the tester to the tester, Further, the counter circuit sequentially connects a plurality of latch circuits for a predetermined number of counts, inputs the light reception signal to the input terminal of the first stage latch circuit, and the output of the last stage latch circuit is input to the fire signal transmission circuit. The multiple latch circuits latch the signal state at the input terminal in synchronization with the oscillation pulse of the test light source and output it to the next latch circuit, and the final latch circuit outputs the signal to the fire signal sending circuit. Are output between the latch circuits and the latch circuit outputs, and the output of the latch circuit is delayed for a time longer than the light emission cycle time of the test light emitting unit. Provided with a delay unit that outputs to the input terminal and clear terminal of the latch circuit It is characterized by that.
[0017]
As described above, since the present invention can remotely test a photoelectric smoke detector with a two-wire system, it can be installed in a fire alarm facility using a sensor as compared with a conventional smoke detector with a three-wire remote test function. The cost can be reduced, and the existing two-wire fire alarm system can be easily replaced with the photoelectric smoke detector with a remote test function of the present invention simply by adding a new test repeater. .
[0018]
The counter circuit of the photoelectric smoke detector according to the present invention includes a first D-FF, a second D-FF, a first delay unit, and a second delay unit. The first D-FF inputs the received light signal to the data input terminal D, Test light source In synchronization with the oscillation pulse (clock input), the signal state of the data input terminal D is latched to obtain the signal state of the output terminal Q. The second D-FF connects the output terminal Q of the first D-FF to the data input terminal D and connects the output terminal Q to the fire signal transmission circuit. Test light source The signal state of the data input terminal D is latched in synchronism with the oscillation pulse, and the signal state of the output terminal Q is obtained.
[0019]
The first delay unit outputs the output signal (inverted to H level or L level) of the output terminal Q of the first D-FF. Delayed for longer than the light emission cycle time of the test light emitting section Apply to the data input terminal D and the clear terminal CLR of the second D-FF. The second delay unit delays the output signal (inversion to H level or L level) of the inverting output terminal Q * of the second D-FF for a predetermined time and applies the delayed signal to the clear terminal CLR of the first D-FF. Note that the inverted output of the D-FF is represented by adding “*” after Q in the specification. On the other hand, in the drawings, “-” is attached on Q as usual.
[0020]
Here, the first delay unit connects the first resistor and the second resistor in series to a connection line connecting the output terminal Q of the first D-FF, the data input terminal D of the second D-FF, and the clear terminal CLR. A first capacitor is connected between the two resistors and between the output terminal Q of the second D-FF.
[0021]
The second delay unit connects a third resistor and a fourth resistor in series to a connection line between the inverting output terminal Q * of the second D-FF and the clear terminal CLR of the first D-FF, and the two resistors. A second capacitor is connected between the capacitor and ground.
[0022]
By such a counter circuit with a delay function, when the first D-FF counts the received light signal 1 in synchronization with the first test oscillation pulse and inverts the output Q to the H level, the first delay unit Delayed for longer than the light emission cycle time of the test light emitting unit The data input terminal D of the second D-FF becomes H level, for example, the output Q of the second D-FF is inverted to H level in synchronization with the third test oscillation pulse, and a signal based on 2 counts is output. A fire signal is sent by turning on.
[0023]
When the output Q of the second D-FF based on 2 counts is inverted to the H level, the inverted output Q * is simultaneously inverted to the L level, whereby the second delay unit applies a predetermined voltage to the clear terminal CLR of the first D-FF. Clear with time delay. As a result, a test fire signal having a time width T obtained by adding the clear delay time of the second D-FF by the first delay unit to the clear delay time of the first D-FF by the second delay unit is transmitted.
[0024]
For this reason, even if the light emission timing of the main light source is at a position immediately after the second test light emission pulse, the second D-FF is in the middle of 1 count and 2 counts by the first delay unit at this time, and the fire signal is transmitted. Therefore, even if the counter is reset by the main light emission pulse, the fire signal is not affected.
[0025]
In addition, resetting the counter circuit with the main light emission pulse causes 2 counts of the test light emission pulse to be restarted. At this time, since the delay by the first delay unit is performed in the middle, the counter is counted with 2 counts synchronized with the two test light emission pulses. An output is obtained and a fire signal can be sent out.
[0026]
Therefore, for a self-recovery photoelectric smoke detector that outputs a fire signal to the outside only during fire detection, a test for remote testing is performed asynchronously with the light emission timing of the main light source used for normal fire monitoring. Even if the light is emitted, it is possible to send a fire signal as a test result with a time width that can be easily identified on the tester side with a predetermined number of test light emission without any problem, and external test depending on the timing of the main light emission pulse with respect to the test light emission This prevents the problem of outputting a fire signal that cannot be identified by the tester as a test result, enabling a highly reliable remote test.
[0027]
Further, the photoelectric smoke detector of the present invention is disposed in the vicinity of the main light source of the light emitting unit, receives a light from the main light source and outputs a monitoring light receiving signal, and a monitoring light receiving unit from the monitoring light receiving unit. A main light source emission monitoring circuit that allows test control by the test control circuit when the monitoring light reception signal is obtained intermittently and prohibits the test control by the test control circuit when the monitoring light reception signal cannot be obtained is provided. It is characterized by that. This monitoring light-receiving unit is, for example, a phototransistor disposed close to the main light source.
[0028]
In this way, by arranging a light receiving element such as a phototransistor that directly detects the light in the vicinity of the main light source to obtain a sufficient light receiving signal, monitoring by amplification of the light receiving signal of irregularly reflected light in the chamber as in the prior art, etc. The state of the main light source is easily detected without requiring a complicated circuit, and if the main light source is abnormal, the test operation is prohibited to prevent erroneous test results from being produced.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram of a fire alarm system in which the photoelectric smoke detector of the present invention is used, and shows a state in which a tester is connected for a remote test.
[0030]
In FIG. 1, a repeater 2 is connected to the signal line SL and the common line SC drawn from the receiver 1, and a pair of power-supply signal lines including a signal line 3 a and a common line 3 b are drawn from the repeater 2. A plurality of photoelectric smoke detectors 4a to 4n according to the present invention are connected to the signal line 3a and the common line 3b. A termination device 5 for disconnection monitoring is connected to the termination.
[0031]
The tester 6 is connected to the repeater 2. The relay device 2 is provided with a relay contact Ly, and a remote test is performed by operating a relay (not shown) of the relay device 2 according to an operation signal from the test device 6 and switching the relay contact Ly to the test device 6 side. . By switching the relay contact Ly to the tester 6 side, the test line loop is switched to the tester 6, the repeater 2, and the photoelectric smoke detectors 4a to 4n.
[0032]
When a test operation is performed by the tester 6, a test command is sent, and remote tests of the photoelectric smoke detectors 4a to 4n are sequentially performed. The test command from the tester 6 is a unique address method in which a test is performed by designating a unique address of the sensor, or a common address common to all sensors is designated, and a delay time different from the command reception on the sensor side. It is possible to apply a common address method for performing a remote test after each delay time.
[0033]
The addresses assigned in advance to the fire detectors 4a to 4n by the test command of the remote test from the tester 6, for example, No. 1-No. When the remote tests are performed in the order of n, each time a remote test is performed on each sensor, a fire signal is sent out in the normal state. This fire signal is received by the tester 6 and all sensor tests are performed. The test result will be displayed when the is completed.
[0034]
The number of photoelectric smoke detectors 4a to 4n connected to the signal line 3a and the common line 3b from the repeater 2 is arbitrary, but for example, a maximum of 16 can be installed. In the remote test, the tester 6 can perform the remote test in order from the first sensor to the last sensor by setting the number of sensors connected to the sensor line.
[0035]
FIG. 2 is an explanatory diagram of the tester 6 of FIG. The tester 6 is a portable device, and as shown in the drawing, an execution switch 7, a display unit 8 using two 7-segment displays, a normal test display lamp 9, and a test result display lamp 10 on the surface panel. In addition, a selection switch 11 is provided.
[0036]
As shown in FIG. 1, when the tester 6 is connected to the repeater 2, for example, the selection switch 11 sets the number of sensors to be subjected to the remote test, and when the execution switch 7 is pressed, the remote test is started. During the remote test, the normal test indicator light 9 changes from lighting to blinking, and returns to lighting when the test is completed.
[0037]
If the test results of all the sensors are normal, the test result indicator lamp 10 lights up in green, for example. On the other hand, when there is an abnormality in one or a plurality of fire detectors, the test result display lamp 10 is lit red. For this reason, as the test result display lamp 10, for example, a two-color LED is used.
[0038]
When an abnormality display is performed with the test result indicator lamp 10, the sensor number is displayed on the display unit 8. In this case, when there is an abnormality in two or more sensors, the selection of the selection switch 11 can switch and display the sensor number where the abnormality has occurred.
[0039]
FIG. 3 is a block diagram illustrating an embodiment of a photoelectric smoke detector according to the present invention having the remote test function of FIG.
[0040]
In FIG. 3, the photoelectric smoke detector of the present invention is divided into a circuit part for normal fire detection and a circuit part for remote testing. As a normal fire detection circuit section, there are a rectification / noise absorption circuit 15, a 3 volt constant voltage circuit 17, a fire signal output circuit 18, a constant voltage current limiting circuit 19, a main light source driving circuit 20, a main light source LED 21, a light reception signal amplification. A circuit 22, a light receiving element 23 using a photodiode, a counter circuit 24, and a main light source oscillation circuit 25 are provided.
[0041]
In contrast, the remote test interface circuit 16, test control circuit 26, test light source oscillation circuit 27, test light source drive circuit 28, test light source LED 29, main light source light emission monitoring circuit 30, and counter circuit 24 are provided as circuits for remote testing. An OR circuit 32 for supplying a clock synchronized with the oscillation pulse is provided.
[0042]
FIG. 4 is a plan view of the detector structure of the photoelectric smoke detector of the present invention. In FIG. 4, a smoke detection area 36 is provided inside the sensor body 33. The smoke detection area 36 has an inflow port on a cylindrical peripheral wall around the smoke detection area 36 and a labyrinth structure inside. In the smoke detection region 36, a light emitting unit 34 and a light receiving unit 35 are provided.
[0043]
FIG. 5 shows the internal structure in section by taking out the light emitting part 34 and the light receiving part 35 of FIG. In FIG. 5, a main light source LED 21 is accommodated in the light emitting unit 34 and intermittently emits light for smoke detection in the optical axis direction. A light receiving unit 35 is disposed with an optical axis having a crossing angle of 70 ° with respect to the optical axis of the light emitting unit 34, and the light receiving element 23 is accommodated in the light receiving unit 35.
[0044]
For this reason, the light from the main light source LED 21 hits and reflects the smoke particles flowing into the smoke detection region, and the scattered light obtained by the reflection is received by the light receiving element 23 and output as a light reception signal.
[0045]
The test light source LED 29 used for the remote test is disposed on the side of the light receiving surface of the light receiving element 23 housed in the light receiving unit 35. For this reason, when the test light source LED 29 emits light by a remote test, the light is directly applied to the light receiving element 23, and a light reception signal for the test can be obtained.
[0046]
The light emitting unit 34 is provided with a phototransistor 31 as a monitoring light receiving element for monitoring whether the main light source LED 21 emits light normally. The phototransistor 31 is disposed at a position close to the side off the optical axis of the light emitting surface of the main light source LED 21 housed in the light emitting unit 34, and directly receives the light from the main light source LED 21, A light receiving signal for monitoring having a proper level is detected.
[0047]
6 is a cross-sectional view taken along the line AA in FIG. In FIG. 6, the light source 34 houses the main light source LED 21, and a phototransistor 31 as a monitoring light receiving element is arranged at a position close to the upper side on the tip side. A light receiving element 23 is housed in the light receiving section 35, and a test light source LED 29 is disposed on the side thereof.
[0048]
Here, with reference to FIG. 3, the operation during normal fire monitoring will be briefly described. A prescribed DC power supply voltage is supplied between the signal line L and the common line C from the receiver 1 shown in FIG. 1 via the repeater 2, and power is supplied to the inside of the sensor via the rectification / noise absorption circuit 15. Have been supplied.
[0049]
As a result, the main light source oscillation circuit 25 operates, and an oscillation pulse having a pulse width t1 is output to the main light source drive circuit 20 in the period T1 to intermittently emit the main light source LED 21. The period T of the main light source oscillation pulse is, for example, T1 = 2.5 sec, and the pulse width t1 is t1 = 40 μsec.
[0050]
The light emitted from the main light source LED 21 is applied to the smoke detection region as apparent from the scattered light type smoke detection structure of FIG. 5, and if smoke is flowing at this time, it is reflected by the smoke particles and the scattered light is received. Incident on the element 23. A light reception signal by scattered light received by the light receiving element 23 is amplified by the light reception signal amplification circuit 22 and then input to the counter circuit 24.
[0051]
As will be apparent from the following description, the counter circuit 24 is provided with two D-FFs so that the counter output terminal Q is set to H level by 2 counts of the main light source oscillation pulse. For this reason, the main light source oscillation pulse is supplied to the clock terminal CK from the main light source driving circuit 20 via the OR circuit 32 to the counter circuit 24 as a clock signal.
[0052]
When the counter circuit 24 counts 2 and the output terminal Q is set to H level, this H level output is input to the fire signal output circuit 18 and the built-in switching transistor is turned on, and the signal line L is connected to the common line C. A fire signal is sent to the receiver 1 side by flowing a notification current.
[0053]
When the fire is extinguished and smoke does not flow in, the light reception signal from the light reception signal amplification circuit 22 becomes L level, so that the output terminal Q of the counter circuit 24 returns from H level to L level, thereby the fire signal output circuit. 18 also turns off and stops sending fire signals.
[0054]
FIG. 7 is a circuit block diagram showing a specific example of a circuit block necessary for the remote test in FIG.
[0055]
FIG. 7 shows circuit configurations of the fire signal output circuit 18, the main light source driving circuit 20, the counter circuit 24, the test control circuit 26, the main light source light emission monitoring circuit 30 and the test light source oscillation circuit 27, and the remote test interface circuit 16. The received light signal amplification circuit 22, the main light source oscillation circuit 25, and the test light source drive circuit 28 are represented by circuit blocks as in FIG. 3, and other circuits are omitted.
[0056]
In FIG. 7, first, the main light source oscillation circuit 25 oscillates a pulse having a period T1 = 2.5 sec and a pulse width t1 = 40 μsec and supplies the pulse to the main light source drive circuit 20. The main light source driving circuit 20 includes an electrolytic capacitor C4, transistors Q4 and Q5, a main light source LED 21, resistors R7 to R12, and a diode D10.
[0057]
When power is supplied to the sensor, the output from the constant voltage current limiting circuit 19 shown in FIG. 3 gradually charges the electrolytic capacitor C4, and the voltage between the terminals is normally monitored after about 10 to 15 seconds. Reach voltage.
[0058]
The oscillation pulse from the main light source oscillation circuit 25 supplies the base current to the transistor Q5 via the resistor R12, whereby the transistor Q5 is turned on, and at the same time, the base current flows also to the transistor Q4 via the resistor R10 and the diode D10. Turn on. When the transistors Q5 and Q4 are turned on, the charge of the electrolytic capacitor C4 flows through the loop of the main light source LED21 and resistor R8 connected to the emitter side of the transistor Q4, and the main light source LED21 is driven to bring the pulsed light into the smoke detection region. Output.
[0059]
The counter circuit 24 is a circuit that operates the fire signal output circuit 18 to send out a fire signal when a light receiving signal exceeding a threshold value is continuously output twice in a state where smoke is detected from the light receiving signal amplification circuit 22. is there.
[0060]
Therefore, the counter circuit 24 includes D-FFs 37 and 38, resistors R13 to R16, capacitors C8 and C9, and diodes D4 to D7. The D-FFs 37 and 38 include a data input terminal D, an output terminal Q, an inverted output terminal Q *, a clock terminal CK, and a clear terminal CLR.
[0061]
When the power is turned on, the D-FFs 37 and 38 are cleared when the clear terminal CLR of the D-FF 37 becomes L level, and each output terminal Q is set to L level and the inverted output terminal Q * is set to H level.
[0062]
When the clear terminal CLR of the D-FF 37 is in the normal monitoring state with the H level state and the clock is supplied to the clock terminal CK, the H level which is the signal state of the data input terminal D is latched, and the output terminal Q is set to the L level. The level is inverted from the H level, and at the same time, the inverted output terminal Q * is inverted from the H level to the L level.
[0063]
The data input terminal D and the clear terminal CLR of the D-FF 38 are set to the H level by the latch operation of the D-FF 37. If the data input terminal D is at the H level at the next clock input, the D-FF 38 is the same as the D-FF 37 described above. The output terminal Q changes from L level to H level, the inverted output terminal Q * changes from H level to L level, and the H level signal at the output terminal Q drives the fire signal output circuit 18.
[0064]
In the counter circuit 24, the output of the light receiving signal amplifier circuit 22 is connected to the data input terminal D of the preceding D-FF 37, and the output terminal Q is connected to the second stage D− via the resistors R 13 and R 14 of the first delay unit 39. It is connected to the data input terminal D of FF38. The output Q of the second stage D-FF 38 is connected to the fire signal output circuit 18.
[0065]
The first delay unit 39 includes resistors R13 and R14 and a capacitor C8. Specifically, the resistors R13 and R14 are inserted into a line connecting the output Q of the D-FF 37 and the data input terminal D of the D-FF 38, and an output line from the output Q of the D-FF 38 is inserted between the resistors R13 and R14. And a capacitor C8.
[0066]
For this reason, when the output Q of the preceding D-FF 37 is inverted from the L level to the H level, the first delay unit 39 determines the signal level of the data input terminal D of the second D-FF 38 after the delay time by the time constant τ4. Is set to H level.
[0067]
The counter circuit 24 is provided with a second delay unit 40, and the second delay unit 40 includes resistors R15 and R16 and a capacitor C9. In the second delay unit 40, resistors R15 and R16 are inserted and connected in series to the connection line from the inverted output Q * of the second-stage D-FF 38 to the clear terminal CLR of the first-stage D-FF 37. And R16 and a capacitor C9 are connected to the common line side.
[0068]
For this reason, when the output Q of the second-stage D-FF 38 becomes H level and the fire signal is transmitted by two consecutive counts of the light reception signal of the counter circuit 24, the second delay unit 40 simultaneously reverses Q. * Although the output changes from H level to L level, the change to L level is delayed by the time constant τ5 of the second delay unit 40 and added to the clear terminal CLR of the first stage D-FF 37, so that the counter output The subsequent clear operation is delayed.
[0069]
Here, the time constant τ4 of the first delay unit 39 and the time constant τ5 of the second delay unit 40 are set to substantially the same value. The diode D5 provided on the connection line from the test control circuit 26 side to the second delay unit 40 is used to cancel the clear prohibition of the D-FF 37 during the remote test.
[0070]
Further, the clock for the clock terminal CK of the D-FF 37 provided in the counter circuit 24 is supplied via the diode D6 or D7. The diode D7 supplies the drive signal of the main light source drive circuit 20 to the D-FFs 37 and 38 as a clock. The diode D6 also supplies a drive signal from the test light source drive circuit 28 to the D-FFs 37 and 38. For this reason, clocks are received from both the main light source light emission drive and the test light source light emission drive. That is, the diodes D6 and D7 constitute the OR circuit 32 shown in FIG.
[0071]
Next, the fire signal output circuit 18 will be described. The fire signal output circuit 18 includes Darlington-connected transistors Q1 and Q2, an operation indicator LED1, Zener diodes ZD1 and ZD2, and resistors R1 to R3. When a fire is detected, the output Q of the D-FF 38 of the counter circuit 24 becomes H level, whereby a base current flows from the resistor R3 to the transistor Q2, the transistors Q2 and Q1 are turned on, and the signal line L to the common line C is notified. A fire signal is sent by passing an electric current.
[0072]
At this time, the operation indicator lamp LED1 is turned on by the alarm current to notify the fire detection. The maximum current flowing through the operation indicator lamp LED1 is limited by the Zener diode ZD1 connected to both ends of the current flowing through the series circuit of the operation indicator LED1 and the resistor R1.
[0073]
Upon receiving the test command from the tester 6 shown in FIG. 1, the remote test interface circuit 16 outputs a test signal E1 to the test control circuit 26 for a certain period T0, for example, T0 = 120 msec.
[0074]
The test light source oscillation circuit 27 includes a NAND Schmitt trigger 41, resistors R37 and R38, a capacitor C18, a diode D9, and a delay capacitor D40 that also serves as noise prevention. The test light source oscillation circuit 27 stops the oscillation operation when the input from the test control circuit 26 side to the NAND Schmitt trigger 41 is L level, and starts the oscillation operation when it becomes H level.
[0075]
The test oscillation pulse in this case has, for example, a cycle T2 = 8 ms and a pulse width t2 = 10 μs, and the test operation is performed by setting the cycle sufficiently shorter than the cycle T1 = 2.5 s of the main light source oscillation pulse of the main light source oscillation circuit 25. Can be done in a short time. The oscillation pulse from the test light source oscillation circuit 27 is input to the test light source drive circuit 28, and light emission is driven by flowing a drive current to the test light source LED 29 connected as a load via a resistor R47.
[0076]
The main light emission monitoring circuit 30 includes a phototransistor 31, resistors R39 to R42, an FET 42, a diode D8, a capacitor C19, and a NAND Schmitt trigger 43. The circuit function prohibits signal processing of a remote test from the external tester 6 when the main light source LED 21 is in a light emission stop state.
[0077]
In the main light source emission monitoring circuit 30, when the main light source LED 21 emits light in normal monitoring, the phototransistor 31 disposed in the vicinity thereof is turned on as shown in FIG. When the phototransistor 31 is turned on, the divided voltage of the resistors R41 and R42 is supplied to the gate G of the FET 42, and when the FET 42 is turned on, the charge of the capacitor C19 is discharged via the resistor R39. For this reason, the input of the NAND Schmitt trigger 43 is L level, and the output is H level.
[0078]
Subsequently, until the main light source LED 21 emits light again, the capacitor C19 is charged through the resistor R40, so that the voltage between the terminals slightly rises, but the operation of being discharged by the light emission of the main light source LED 21 is repeated again. Therefore, when the main light source LED 21 emits light normally, the input of the NAND Schmitt trigger 43 is maintained at the L level, and as a result, the output is in the H level state, and the resistance R32 on the test control circuit 26 side and the counter circuit 24 side The clear terminal CLR of the D-FF 37 provided in the counter circuit 24 is set to the H level via the diode D5, and the clear is prohibited.
[0079]
On the other hand, when the main light source LED 21 stops emitting light, the capacitor C17 continues to be charged through the resistor R40, the voltage across the capacitor C19 increases, and the output of the NAND Schmitt trigger 32 is inverted to the L level.
[0080]
As a result, the emitter-side voltage of the transistor Q9 of the test control circuit 26 described later becomes 0 volts, and the test operation is prohibited because it becomes impossible to respond to the test signal E1 from the remote test interface circuit 16 by the remote test. For this reason, even if a test command is sent from the external tester side, the failure of the sensor can be confirmed by not sending a fire signal due to the test.
[0081]
Next, the test control circuit 26 will be described. The test control circuit 26 is a circuit for remotely testing the sensor, and performs a test operation based on a test signal E1 output from the remote test interface circuit 16 that has received a test command from an external tester. That is, when the test signal E1 is obtained, the test light source oscillation circuit 27 and the test light source drive circuit 28 are operated, and the test light source LED 29 irradiates the test light to the light receiving element 23 and emits the same operation as when smoke is detected. And send a fire signal to the tester 6.
[0082]
First, in the normal monitoring state, the output of the NAND Schmitt trigger 43 of the main light source emission monitoring circuit 30 is at the H level if the main light source LED 21 is operating normally. In this state, when the remote test interface circuit 16 outputs an H level signal as a test signal E1 in response to a test command from an external tester, a base current flows to the transistor Q8 via the resistor R30, and the transistor Q8 is turned on. When the transistor Q8 is turned on, the clear inhibition by the diode D5 of the counter circuit 24 is released.
[0083]
When the transistor Q8 is turned on, the base current also flows to the transistor Q9 via the resistor R34 and the capacitor C16, and the transistor Q9 is turned on for a predetermined time τ3 determined by the time constant τ3. Here, a timer 44 is constituted by the transistor Q9, the resistor R34 and the capacitor C16.
[0084]
When the transistor Q9 is turned on, a current flows through the resistor R35 connected to the collector side thereof, so that the input of the NAND Schmitt trigger 41 provided in the test light source oscillation circuit 27 via the delay circuit composed of the resistor R36 and the capacitor C40. Is set to the H level, and the test oscillation pulse is oscillated.
[0085]
At the same time, the output of the fire signal from the inverted output Q * of the second stage D-FF 38 of the counter circuit 24 is monitored via the resistor R36 and the diode D4. In this state, the fire signal is output by 2 counts of the counter circuit 24, and when the inverted output Q * of the D-FF 38 is inverted from the H level to the L level, the NAND circuit after a predetermined time by the delay circuit of the resistor R36 and the capacitor C40 The input of the Schmitt trigger 41 is pulled to L level, and the oscillation operation of the test light source oscillation circuit 27 is stopped.
[0086]
Here, the time τ3 during which the transistor Q9 is turned on by the timer 44 provided in the test control circuit 26 is a time determined by the time constant of the resistor R34 and the capacitor C16, and during this predetermined time τ3, In that case, a maximum of four test oscillation pulses are required. For this reason, the predetermined time τ3 of the timer 44 is, for example, 3 × 8 ms = 24 ms or more obtained by multiplying the oscillation period τ2 of the test light source oscillation circuit 27 by the necessary number of oscillation pulses 4 and within a time necessary for a series of test operations. For example
30ms <τ3 <50ms
And
[0087]
Next, the operation at the time of the remote test in FIG. 7 will be described in relation to the light emission timing of the main light source which is performed asynchronously with the test light emission.
[0088]
FIG. 8 is a time chart at the time of a test operation when the main light emission pulse is present at a position sufficiently away from the test light emission pulse.
[0089]
When the remote test interface circuit 16 in FIG. 7 receives a test command from an external tester, the test signal E1 is raised from L level to H level as shown in FIG. When the test signal E1 rises to the H level, the transistor Q8 of the test control circuit 26 is turned on and the clear prohibition of the D-FF 37 of the counter circuit 24 is released.
[0090]
When the transistor Q9 is turned on, the timer 44 is turned on for a predetermined time τ = 30 ms as shown in FIG. 8B, whereby the test light source oscillation circuit 27 is operated, and the cycle T2 as shown in FIG. 8C. A test light emission pulse having a pulse width t2 is oscillated, and the test light source drive circuit 28 intermittently drives the test light source LED 29 to emit light.
[0091]
In contrast to such a test light emission pulse, the main light emission pulse by the main light source oscillation circuit 25 is obtained at a timing deviating from the test light emission pulse as shown in FIG. 8D.
[0092]
The test light emission pulse in FIG. 8C is given from the test light source driving circuit 28 to the counter circuit 24 via the diode D6, and becomes a clock input to the clock terminals CK of the D-FFs 37 and 38. Before starting the test, both the D-FFs 37 and 38 of the counter circuit 24 are in a clear state.
[0093]
When a clock based on the test light emission pulse is applied in a state where the test light of the light receiving element 23 is received by the first test light emission pulse in FIG. The H level signal state of the terminal D is latched, and the output Q is inverted from the L level to the H level as shown in FIG. Of course, at this time, as shown in FIG. 8F, the clear terminal CLR of the D-FF 37 is at the H level where the clear prohibition is released.
[0094]
When the first stage D-FF 37 is inverted by the first test light emission pulse and the output Q becomes H level, the H level output is delayed by the first delay unit 39 and the data input terminal of the second stage D-FF 38. Join D. Therefore, as shown in FIG. 8G, the level of the data input terminal D of the D-FF 38 increases according to the time constant τ 4 of the first delay unit 39.
[0095]
Here, since the time constant τ4 of the first delay unit 39 is larger than the cycle T2 of the test light emission pulse, the signal level of the data input terminal D of the D-FF when the second test light emission pulse is obtained as a clock input. Is logically at the L level without reaching the threshold level TH. For this reason, even if a light reception signal based on the second test light emission pulse is obtained, the counter circuit 24 does not perform the second count operation.
[0096]
When the timing of the second test light emission pulse has passed, the signal level of the data input terminal D of the D-FF 38 exceeds the threshold level TH and becomes logically H level by the time constant τ4 by the first delay unit 39. For this reason, the D-FF 38 latches the H-level signal state of the data input terminal D and inverts the output Q from the L level to the H level by the light reception signal and the clock input by the third test light emission pulse, and simultaneously inverts it. The output Q * is inverted from H level to L level.
[0097]
The transistors Q2 and Q1 of the fire signal output circuit 18 are turned on by the H level output of the output Q of the D-FF 38, and a fire signal is sent to the outside by flowing a notification current between the signal line L and the common line C. Also, the operation indicator LED1 is turned on.
[0098]
At this time, since the capacitor C8 of the first delay unit 39 is at the H level on both ends, the capacitor C8 is instantaneously charged and the signal level for the data input terminal D of the D-FF 38 is raised to the H level.
[0099]
When the inverted output Q * of the D-FF 38 is inverted from the H level to the L level, the L level output is applied to the clear terminal CLR of the first stage D-FF 37 via the second delay unit 40. That is, due to the fall of the L level of the inverted output Q * of the D-FF 38 by the third test light emission pulse, the charge of the capacitor C9 of the second delay unit is discharged through the resistor R15, and as shown in FIG. Thus, the clear input applied to the clear terminal CLR of the first stage D-FF 37 decreases according to the time constant τ 5 of the second delay unit 40.
[0100]
When the clear input that is the output of the second delay unit 40 falls below the threshold level TH, the clear terminal CLR of the D-FF 37 is logically set to the L level and clearing is performed, and the D-FF 37 is cleared. The output Q is inverted from H level to L level.
[0101]
When the output Q of the D-FF 37 falls to the L level, the L level output decreases the input level of the data input terminal D of the D-FF 38 via the first delay unit 39 according to the time constant τ4. Then, as shown in FIG. 8G, when it falls below the threshold level TH, it logically becomes L level, so that the D-FF 38 is cleared as a clear input, and the output Q of the D-FF 38 is simultaneously changed from H level to L level. The inverted output Q * changes from the L level to the H level to return to the initial state. For this reason, the transistors Q2 and Q1 of the fire signal output circuit 18 are turned off to stop the fire signal output.
[0102]
If the delay time until clearing by the second delay unit 40 in FIG. 8F is Td5 and the delay time until clearing by the first delay unit 39 in FIG. 8G is Td4, the delay time in FIG. The output time T6 of the fire signal determined by the H level period of the output Q of the D-FF 38 is obtained by adding two delay times.
T6 = Td5 + Td4
For example, the time is about T6 = 20 ms.
[0103]
With respect to the output of the fire signal from the sensor during such a remote test for T6 time, the tester provided outside receives, for example, a fire signal of 8 ms or more which is the same as the cycle T2 of the test light emission pulse. The test result is judged to be normal.
[0104]
FIG. 9 is a time chart when the main light emission pulse is located immediately after the second test light emission pulse in the test operation by the remote test in the embodiment of FIG. 7, and FIG. 9 (A) to (I). Each signal is the same as in FIG.
[0105]
Assume that the main light emission pulse of FIG. 9D is positioned at a timing immediately after the second test light emission pulse with respect to the test light emission pulse of FIG. 9C. In this case, during the light emission by the main light emission pulse, the scattered light from the smoke does not enter the light receiving element 23, and the light reception signal from the light reception signal amplification circuit 22 to the counter circuit 24 is at the L level where no fire is detected.
[0106]
Therefore, the D-FF 37 in the first stage, which has performed the count operation by the first test light emission pulse at the clock input by the main light emission pulse, latches the light reception signal L level at the time of the main light emission pulse, and FIG. As shown in E), the reset operation is performed to change the output Q from the H level to the L level.
[0107]
For this reason, the Q output of the D-FF 37 is reset to the same L level as before the test. The signal state delayed by the first delay unit 39 and applied to the data input terminal D of the second-stage D-FF 38 is as shown in FIG. That is, at the rise of the output Q of the D-FF 37 to the H level by the first test light emission pulse, the output of the first delay unit 39 that is the input of the data input terminal D of the D-FF 38 increases with the time constant τ4. The decrease starts with the reset by the main light emission pulse, and this change is made below the threshold level TH.
[0108]
When the third test light emission pulse in FIG. 9C is obtained following the main light emission pulse in FIG. 9D, the first-stage D-FF 37 receives the H level light reception as shown in FIG. 9E. The output Q is changed from L level to H level by operating in the same manner as the first test light emission pulse with the signal and the clock input at that time.
[0109]
For this reason, as shown in FIG. 9G, the level of the data input terminal D of the D-FF 38 starts increasing again halfway due to the delay of the first delay unit 39, and in this case, the increase due to the delay has already progressed. Thus, before reaching the timing of the fourth test light emission pulse, the signal level at the data input terminal D of the D-FF exceeds the threshold level TH and becomes H level.
[0110]
Accordingly, the D-FF 38 inverts the output Q from the L level to the H level as shown in FIGS. 9 (H) and (I), and simultaneously the inverted output Q * is at the H level as shown in FIGS. From the fire signal output circuit 18 to the outside. The recovery operation after outputting the fire signal in this way is the same as in the case of FIG.
[0111]
As described above, in the counter circuit 24 of the present invention, even if the main light emission pulse is obtained and the counter reset is performed immediately after the second test light emission pulse, the counter reset state by this main pulse is not performed. Since the fire signal is not output, the counter circuit 24 is simply reset, and then the fire signal can be normally output with 2 counts by the test light emission pulse.
[0112]
FIG. 10 shows the operation when the main light emission pulse is obtained at the same timing as in FIG. 9, except for the first delay unit 39 provided in the counter circuit 24 of FIG. 10A to 10H, the output Q of the D-FF 37 of FIG. 10E is the data input terminal of the second stage D-FF 38 by removing the first delay unit 39. Since this is the same as D, the time chart corresponding to (G) in FIG. 9 is omitted.
[0113]
In FIG. 10, since the first delay unit 39 is not provided, the output of the D-FF 38 is changed from the L level to the H level as shown in FIG. 10 (G) at the second test light emission pulse in FIG. 10 (C). Raised to the level and started sending fire signals.
[0114]
When the main light emission pulse is positioned immediately after the second test light emission pulse as shown in FIG. 10D, the first light emission pulse clears the D-FF 37 in the first stage, and the output Q becomes L level. Since there is no delay unit 39, the L level of the output Q becomes the input of the clear terminal CLR of the second stage D-FF 38, and the D-FF 38 is also cleared, and the main light emission pulse is obtained as shown in FIG. Resetting the output Q of the D-FF 38 returns to the L level.
[0115]
For this reason, the fire signal is transmitted over a short time from the second test light emission pulse to the main light emission pulse. The tester provided outside for such a short-time fire signal transmission is too short because, for example, a normal test result is judged by a fire signal of 8 ms or more equal to the cycle of the test light emission pulse. It is ignored as a fire signal, and the test signal cannot be confirmed by the fire signal due to the fire signal.
[0116]
Subsequently, the fire signal is output by the counter circuit 24 after resetting by the main light emission pulse by the third test light emission pulse and the fourth test light emission pulse. However, even if the second fire signal has a sufficient duration, the external tester judges the test result for the fire signal received first, and the second fire signal is a circuit. The test result is not confirmed by this fire signal.
[0117]
The malfunction during the test when the first delay unit 39 shown in FIG. delay A fire having a sufficient time width that can be identified on the tester side even if the main light emission pulse is located immediately after the second test light emission pulse, as shown in the time chart of FIG. Signals can be sent out as test results.
[0118]
FIG. 11 is a time chart when the main light emission pulse is positioned while the fire signal is being output by 2 counts of the counter circuit 24 based on the test light emission pulse. In this case, the third test light emission pulse as shown in FIG. 11C causes the output Q of the second stage D-FF 38 to become H level as shown in FIG. A fire signal is output from the circuit 18 to the outside.
[0119]
If a main light emission pulse is obtained immediately after the third test light emission pulse as shown in FIG. 11D, the first-stage D-FF 37 is reset as shown in FIG. 11E by this main light emission pulse. As a result, the output Q changes from H level to L level. Therefore, as shown in FIG. 11 (G), the delay output to the data input terminal D and the clear terminal CLR of the second stage D-FF 38 starts to decrease according to the time constant τ4 of the first delay unit 39, and falls below the threshold level TH. D-FF38 is cleared and fire signal output is stopped.
[0120]
However, the main light emission pulse during the output of the fire signal only changes the timing of the delay start of the time constant τ4 by the first delay unit 39 as shown in FIG. The fire signal output time T6 determined by the H level period of the output Q of the D-FF 38 is equal to or longer than the delay time Td4 of the first delay unit 39 even if the main light emission pulse substantially coincides with the third test light emission pulse. Have enough time.
[0121]
For this reason, even if the main light emission pulse is reset at the timing when the fire signal is being output, a fire signal as a test result having a sufficient time width that can be identified as a test result on the external tester side must be sent. Can do.
[0122]
In addition, this invention is not limited to said embodiment, The appropriate deformation | transformation which does not impair the objective and advantage is included, and limitation by the numerical value shown to said embodiment is not received.
[0123]
【The invention's effect】
As described above, according to the present invention, the light emission of the main light source used for normal fire monitoring in the self-healing photoelectric smoke detector that outputs the fire signal to the outside only during the fire detection is performed. Even if test light emission for remote testing is performed asynchronously with the timing, a fire signal with a time width that can be sufficiently identified on the tester side can be sent as a test result with a predetermined number of test light emission without any problem. Therefore, it is possible to prevent a problem that a fire signal that cannot be identified by an external tester is output as a test result depending on the timing of the main light emission pulse, and to perform a highly reliable remote test.
[0124]
In addition, during remote testing, the main light source is stopped so that the test operation is prohibited and the abnormality can be confirmed, so that the light emission state of the main light source is detected by a monitoring light-receiving element such as a phototransistor located nearby. Compared to the conventional monitoring by high gain amplification of the scattered light in the chamber by light emission of the main light source, the circuit configuration for main light source light emission monitoring can be greatly simplified, and stable light emission monitoring of the main light source can be achieved. it can.
[0125]
In addition, since the photoelectric smoke detector can be remotely tested with a two-wire system, the equipment cost of a fire alarm facility using the detector can be reduced compared to a conventional smoke detector with a three-wire remote test function. The installed two-wire fire alarm system can be easily replaced with the photoelectric smoke detector with a remote test function of the present invention simply by adding a new test repeater.
[Brief description of the drawings]
FIG. 1 is a block diagram of a fire alarm system in which the photoelectric smoke detector of the present invention is used.
FIG. 2 is an explanatory diagram of a tester used for remote testing in FIG.
FIG. 3 is a block diagram of a photoelectric smoke detector according to the present invention.
FIG. 4 is a plan view of a sensor structure according to the present invention.
5 is an explanatory view showing the internal structure of the light emitting unit and the light receiving unit in FIG. 4 taken out.
6 is a cross-sectional view taken along the line AA in FIG.
7 is a circuit block diagram showing the circuit configuration of the main part of FIG. 3;
8 is a time chart of the test operation when the timing of the test light emission and the main light emission is sufficiently shifted in FIG.
FIG. 9 is a time chart of the test operation when the main light emission pulse is located immediately after the second test light emission pulse in FIG.
10 is a time chart of the test operation when the main light emission pulse is positioned immediately after the second test light emission pulse when the first delay unit is not provided in FIG. 7;
11 is a time chart of the test operation when the main light emission pulse is positioned immediately after the third test light emission pulse in FIG. 7;
[Explanation of symbols]
1: Receiver
2: Repeater
3a, 3b: Sensor line
4a to 4n: Photoelectric smoke detector
5: Terminator
6: Tester
7: Execution switch
8: Display section
9: Normal test indicator
10: Test result indicator lamp
11: Selection switch
15: Rectification and noise absorption circuit
16: Remote test interface circuit
17: 3V constant voltage circuit
18: Fire signal transmission circuit (self-healing type)
19: Constant voltage / current limiting circuit
20: Main light source driving circuit
21: Main light source LED
22: Light reception signal amplification circuit
23: Light receiving element (photodiode PD)
24: Counter circuit (storage circuit)
25: Main light source oscillation circuit
26: Test control circuit
27: Test light source oscillation circuit
28: Test light source drive circuit
29: Test light source LED
30: Main light source emission monitoring circuit
31: Monitoring light receiving element (phototransistor PT)
32: OR circuit
33: Sensor body
34: Light emitting part
35: Light receiver
36: Smoke detection area
37: 1st D-FF
38: 2nd D-FF
39: First delay unit
40: Second delay unit
41, 43: NAND Schmitt trigger
42: FET
44: Timer

Claims (5)

A main light source emission unit that intermittently drives the main light source by the oscillation pulse of the main light source oscillation circuit and irradiates light toward the smoke detection space in the chamber;
A light receiving unit that receives scattered light generated by reflection of light from the main light source on smoke present in the smoke detection space;
A counter circuit that counts when the received light signal obtained by the light receiving unit exceeds a preset threshold, and outputs a signal with a predetermined number of counts;
Switching while the counter circuit outputs a signal, a fire signal output circuit of a self-restoring type that sends a fire signal to the outside through a pair of power supply signal lines;
In the photoelectric smoke detector with
A remote test interface circuit for receiving a test instruction from the outside via the pair of power supply signal lines and outputting a test signal;
A test light emission unit that intermittently drives a test light source with an oscillation pulse of a test oscillation circuit that is asynchronous with the main light source oscillation circuit and has a short cycle, and irradiates the light receiving unit with test light;
The test light emitting unit is operated by a test signal from the remote test interface circuit, a signal is output from the counter circuit with a predetermined number of received light signals from the light receiving unit by intermittent driving of the test light source, and the fire signal A test control circuit for sending a fire signal from a test to a tester from a sending circuit;
Equipped with a,
Furthermore, the counter circuit includes:
A plurality of latch circuits for the predetermined number of counts are sequentially connected, the light reception signal is input to an input terminal of a first-stage latch circuit, and an output of the last-stage latch circuit is input to the fire signal transmission circuit, The latch circuit of the latch latches the signal state of the input terminal in synchronization with the oscillation pulse of the test light source and outputs it as an output signal state and outputs it to the latch circuit of the next stage, and the latch circuit of the final stage outputs a signal to the fire signal sending circuit. A multi-stage latch circuit that outputs the output and clears the latch of the previous latch circuit, and
A delay unit that is provided between the latch circuits, and delays the output of the latch circuit for a time longer than the light emission cycle time of the test light-emitting unit and outputs it to the input terminal and the clear terminal of the latch circuit in the next stage;
A photoelectric smoke detector characterized by comprising: The photoelectric smoke detector according to claim 1,
The counter circuit is
A first D-FF that inputs the received light signal to the data input terminal D, latches the signal state of the data input terminal D in synchronization with the oscillation pulse of the test light source , and sets the signal state of the output terminal Q;
The output terminal Q of the first D-FF is connected to the data input terminal D and the output terminal Q is connected to the fire signal transmission circuit, and the signal state of the data input terminal D is synchronized with the oscillation pulse of the test light source. A second D-FF that latches into the signal state of the output terminal Q;
A first delay unit that delays the output signal of the output terminal Q of the first D-FF for a time longer than the light emission cycle time of the test light-emitting unit and applies it to the data input terminal D and the clear terminal CLR of the second D-FF; A second delay unit that delays the output signal of the inverting output terminal Q * of the second D-FF for a predetermined time and applies it to the clear terminal CLR of the first D-FF;
A photoelectric smoke detector characterized by comprising: In the photoelectric smoke detector according to claim 2,
The first delay unit includes a first resistor and a second resistor connected in series to a connection line connecting the output terminal Q of the first D-FF, the data input terminal D of the second D-FF, and the clear terminal CLR, and the two resistors. And a first capacitor connected between the second D-FF and the output terminal Q of the second D-FF,
The second delay unit includes a third resistor and a fourth resistor connected in series to a connection line between the inverted output terminal Q * of the second D-FF and the clear terminal CLR of the first D-FF, and the two resistors. A photoelectric smoke detector, wherein a second capacitor is connected between the ground and the ground. The photoelectric smoke detector of claim 1, further comprising:
A monitoring light receiving unit that is disposed in the vicinity of the main light source and receives light from the main light source and outputs a monitoring light reception signal;
Test control by the test control circuit is allowed in a state where the monitoring light reception signal from the monitoring light receiving unit is intermittently obtained, and test control by the test control circuit is performed in a state where the monitoring light reception signal is not obtained. Main light emission monitoring circuit to be prohibited,
A photoelectric smoke detector characterized by comprising:   5. The photoelectric smoke detector according to claim 4, wherein the monitoring light receiving unit is a phototransistor disposed close to the main light source.

Images