JPH05225465A - Photoelectric separation type smoke sensor - Google Patents

Abstract

PURPOSE:To reduce the current consumption of a received light amplifier by limiting the time of power supply to the amplifier to only a certain time when light from a light sending part is received by a light reception part and not supplying the power in the other time. CONSTITUTION:A switching element 41 provided on the power line connecting a constant voltage circuit 27 and a received light amplifying circuit 22 is synchronized with the light emission control signal sent from a sending circuit 25 of a switch control means 46. It is turned on by the turning-on signal which is outputted for a period which starts a little before the output period of the light emission control signal and ends a little after this period. Power is supplied to the received light amplifying circuit 22 for a period which starts a little before the period, when light sent from a light sending part 1 based on the light emission control signal of the sending circuit 25 is received by a photodetector (photo diode) 21 of a light reception part 2, and ends a little after this period, and power supply is cut off in the other period. Consequently, the current consumption of the received light amplifying circuit 22 is reduced in comparison with conventional.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has a light-transmitting portion and a light-receiving portion of several meters.
The present invention relates to a power supply control of a photoelectric separation type smoke sensor, which is installed facing each other at a distance of several hundreds of meters, in particular, a light receiving and amplifying circuit that amplifies a light receiving output of a light receiving element.

[0002]

2. Description of the Related Art FIG. 3 is a circuit diagram showing the electrical connection of a conventional photoelectric separation type smoke sensor. In the figure, RE is a fire receiver, 1 is a light-transmitting part of a photoelectric separation-type smoke detector that sends out, for example, near-infrared light, and 2 is several m to several 1 facing the light-transmitting part 1.
It is a light receiving part of the photoelectric separation type smoke detector installed at a distance of 00 m and receiving the light emitted from the light transmitting part 1. 3 is a pair of power source / signal line connecting the light receiving unit 2 and the fire receiver RE, 4 is a power line for supplying power from the light receiving unit 2 to the light transmitting unit 1, and 5 is from the light receiving unit 2 to the light transmitting unit 1. Is a signal line for transmitting a light emission command signal.

Reference numeral 11 is a light emitting diode which is a smoke detecting light emitting element for transmitting the light of the light emitting section 1, and 12 is a light emission control circuit for controlling light emission of the light emitting diode 11 when receiving a light emission command signal. Reference numeral 21 is a photodiode that is a smoke detection light receiving element that receives the light emitted from the light emitting diode 11, 22 is a light receiving amplification circuit that includes a filter unit that amplifies the light receiving output voltage of the photodiode 21, an operational amplification unit, and the like. Reference numeral 23 is a sample hold circuit for temporarily holding the light reception output output from the light reception amplification circuit 22, 24 is a self-address, a DIP switch for setting the distance between the light transmitter 1 and the light receiver 2, and the like 25 is light emission. A sending circuit for sending a command signal to the light emission control circuit 12, 26 is a fire receiver RE
A transmitter / receiver circuit having a parallel-serial converter, a serial-parallel converter, etc. for transmitting a fire signal or the like to the fire receiver or receiving a call signal or the like from the fire receiver RE, 27 is each circuit in the light-receiving unit 2 or light transmission It is a constant voltage circuit that supplies the power required by the unit 1.

Reference numeral 30 designates a fire judging circuit for judging whether or not there is a fire based on the received light output held by the sample and hold circuit 23, a light emitting command circuit for outputting a light emitting command to the sending circuit 25 at a constant cycle, and the like. A processor unit (hereinafter referred to as MPU), 31 is a ROM that stores a program of the fire monitoring system, 32 is a RAMI that stores a timer counter for causing the MPU 30 to perform an arithmetic processing of the light emission period of the light emitting diode 11, 33 Is RAMII as a work area, and IFI to IFIV are interfaces.

The conventional photoelectric separation type smoke detector is constructed as described above, and the MPU 30 is operated by the RAMI 32 at the time of fire monitoring.
Is read out and a light emission command signal is transmitted to the light transmitting section 1 via the transmission circuit 25 every 3 seconds, and the light emission control circuit 12 in the light transmitting section 1 causes the light emitting diode 11 to emit light.

In the light receiving section 2, the light emitting diode 1 of the light transmitting section 1
When the light from 1 is received by the photodiode 21, the light reception output of the photodiode 21 is amplified by the light reception amplification circuit 22, and the light reception output is held by the sample hold circuit 23. The received light output held by the sample hold circuit 23 is read into the MPU 30, digitized, and then compared with a fire determination value, and when a fire is determined, a fire signal is output. The fire signal is sent to the fire receiver RE via the transmission / reception circuit 26.

[0007]

In the conventional photoelectric separation type smoke detector as described above, the light emitting diode 1 of the light transmitting section 1 is used.
The light emitted from 1 is directly received by the photodiode 21, and the light-receiving output of the photodiode 21 is amplified by the light-receiving amplifier 22 and then the MPU 30 constituting the fire discrimination circuit.
The operational amplifier, which is called an operational amplifier, has the advantages that the number of parts of the light receiving amplifier 22 is reduced, a large amplification degree can be easily obtained, and the temperature characteristic is good. Although an operational amplifier is used, it generally has a drawback that the monitoring current of the smoke detector is increased due to the large current consumption. Further, since the light receiving amplifier 22 provided in the light receiving unit 2 is connected to the constant voltage circuit 27 so that power is always supplied, the photodiode 21 of the light receiving unit 2 does not output a light receiving output, and the light receiving amplifier is not output. Even when 22 does not have to be in the operating state, it is in the operating state, the current consumption becomes unnecessarily large, which is uneconomical, and the number of smoke detectors that can be connected to the fire receiver RE decreases. It was happening. Also, the fire receiver RE
If the number of smoke detectors that can be connected to the fire receiver is increased, it is necessary to increase the capacity of the standby power supply provided in the fire receiver RE for a power failure, and as a result, the fire receiver RE becomes large. There were also points.

The present invention has been made to solve the above problems, and limits the time for supplying power to the light receiving amplifier to only a certain period during which the light from the light transmitting section is received by the light receiving section, and otherwise. An object of the present invention is to obtain a photoelectric separated smoke sensor capable of reducing the monitoring current by reducing the current consumption by the light receiving amplifier by not supplying power to the light receiving amplifier.

[0009]

A photoelectric separated smoke detector according to the present invention comprises a light-transmitting portion and a light-receiving portion, which are installed separately and facing each other, and the light-transmitting portion is for smoke detection for emitting light. A light-emitting element and a light-emission control circuit for controlling light emission of the light-emitting element, the light-receiving unit includes a light-receiving element for smoke detection that receives the light of the light-emitting element, and a light-receiving amplifier circuit that amplifies the light-receiving output of the light-receiving element,
Fire discrimination means for discriminating whether or not there is a fire based on the light reception output amplified by the light reception amplification circuit, a constant voltage circuit for supplying drive power to the light reception amplification circuit and fire discrimination means, and a constant light emission control signal for the light emission control circuit A sending circuit that sends in a cycle, a switching element that opens and closes a power supply line that connects the constant voltage circuit and the light receiving and amplifying circuit based on an ON / OFF signal, and a light emission control signal sent from the sending circuit, and emits light. And a switch control means for outputting a switch drive signal to the switching element during a slightly longer period before and after the control signal output period.

[0010]

In the present invention, the switching element provided on the power supply line connecting the constant voltage circuit and the light receiving and amplifying circuit is synchronized with the light emission control signal sent from the sending circuit of the switch control means, and Since it is turned on by the ON signal that is output for a slightly longer period before and after the output period, the light receiving and amplifying circuit receives the light sent from the light sending unit based on the light emission control signal of the sending circuit and receives the light at the light receiving unit. Power is supplied from the constant voltage circuit for a slightly longer period before and after the light is being received by the device, and the power supply is cut off for other periods, and the current consumption by the light receiving amplifier is reduced compared to the past. It

[0011]

1 is a circuit diagram showing an electrical connection of an embodiment of the present invention. In the figure, the same configurations as those of the conventional example are denoted by the same reference numerals as those of the conventional example, and the description of the duplicated configurations is omitted. 22
a is a power supply plus terminal of the light receiving and amplifying circuit 22 and the constant voltage circuit 2
7 is a plus power supply line connecting to the plus terminal, 22b is a minus power supply line connecting the power supply minus terminal of the light receiving and amplifying circuit 22 and the minus terminal of the constant voltage circuit 27 through the ground, and 41 is provided to the minus power supply line 22b. It is a switching element that opens and closes based on an on / off signal.

Reference numeral 42 designates the light emitting period of the light emitting diode 11 as M.
A RAMI storing a counter for performing arithmetic processing in the PU 30, a RAM II storing a counter for performing arithmetic processing in the MPU 30 for the time required for the operation to stabilize after the light receiving and amplifying circuit 22 is energized, 43. 44
Is the time required for the light transmitting unit 1 to receive the light emission command signal and emit light, the photodiode 21 to receive the light, and the sample and hold circuit 23 to hold the light reception output amplified by the light reception and amplification circuit 22. RAMIII, 45 in which a counter for arithmetic processing in the MPU 30 is stored
Is a RAM IV as a work area. These RAMI
42 to RAMIV45 are separated for convenience, but are actually composed of one RAM. IFI to IFV
Is an interface. 46 is a switching element 4
A switch control circuit that controls ON / OFF of MPU3
0 and RAMI 42 to RAMIII 44.

Next, the operation of the above embodiment will be described with reference to the flowcharts of FIGS.

First, the MPU 30 is initialized by pressing the reset button or receiving a power-on or recovery command from the receiver RE (step S).
1), in order to operate the counters as the first to third timers stored in the RAMI 42 to RAMIII 44, the first timer is set to 0 (step S2), and the first timer emits light from the light emitting element 1. It determines the cycle, and its timer time T ₁ is set to, for example, 3 seconds. Next, the MPU 42 operates the counter of the RAMI 42 to operate the first timer (step S3), and when the count value t ₁ reaches T ₁ (step S4), the MPU
30 outputs an ON signal to the switching element 41 to turn ON the switching element 41 (step S5). Furthermore, the MPU 30 activates the counter of the RAMII 43,
The second timer is operated (step S6). This second timer sets the time required for the operation to stabilize after the light receiving and amplifying circuit 22 is energized.
₂ is set to 1 ms, for example. Count value t ₂
When T reaches T ₂ (step S7), the MPU 30 outputs a light emission command to the transmission circuit 25 and causes the transmission circuit 25 to transmit a light emission command signal (step S8). Furthermore, MPU3
0 activates the counter of the RAMIII 44 and activates the third timer (step S9). In the third timer, the light transmitter 1 receives the light emission command signal and emits light, the photodiode 21 receives the light, the light reception amplifier circuit 22 outputs the light reception output, and the sample hold circuit 23 outputs the light reception output. The time required for holding is set, and the timer time T ₃ is set to 1 ms, for example. When the count value t ₃ reaches T ₃ (step S10), MP
U30 outputs an off signal to the switching element 41 to turn off the switching element 41 (step S11).

As described above, in the light receiving and amplifying circuit 22, 1 ms before the photodiode 21 receives the light of the light emitting diode 11 in the light emitting period of 3 seconds, and the light emitting diode 11
1 ms from the reception of the light of the above until the light receiving output of the photodiode 21 is held in the sample hold circuit 23
The power is supplied from the constant voltage circuit 27 for a total of 2 ms, and the power supply is cut off during the other periods, so that the current consumption by the light receiving amplifier 22 is reduced, which is 2
/ 3000.

On the other hand, the received light output received by the photodiode 21 and amplified by the received light amplification circuit 22 is temporarily held by the sample hold circuit 23.
Reads the analog received light output SLV held by the sample hold circuit SH23 (step S1
2) After digitizing it, it is compared with the fire discriminant value F (step S13), and when it is judged that there is a fire, a fire signal is output, and the light receiving unit 2 sends the fire signal to the fire receiver RE (step S14). .. At this time, DIP switch 2
The self-address set to 4 may be added and transmitted.

In the case of the polling type fire alarm system, in the light receiving section 2, the polling signal sent from the fire receiver RE coincides with the self address signal set by the dip switch of the light receiving section 2. Whether or not they match, a code signal such as a fire signal may be sent to the fire receiver RE.

In order to send the light emission command signal from the light receiving section 2 to the light transmitting section 1, instead of using the dedicated signal line 5, the polarity of the power supply line 4 is reversed or a pulse code is superimposed on the power supply voltage. You may make it transmit it.

[0019]

As described above, according to the present invention, the switching element provided in the power supply line connecting the constant voltage circuit and the light receiving and amplifying circuit is synchronized with the light emission control signal sent from the switch control means, and The light receiving element of the light receiving unit turns on the light emitted from the light transmitting unit based on the light emission control signal of the sending circuit, which is turned on by the ON signal output for a little longer period before and after the output period of the light emitting control signal. The power is supplied from the constant voltage circuit for a slightly longer period before and after the light receiving period, and the power supply is cut off during other periods, so the current consumption by the light receiving amplifier is larger than before. It is not necessary to reduce the number of smoke detectors that can be connected to the fire receiver due to the reduction in monitoring current and the increase in the number of smoke detectors. It has no requirement to increase the reserve power capacity for blackout provided in the fire receiver has the effect that the fire receiver is not a large.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an electrical connection of an embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the embodiment of the present invention.

FIG. 3 is a circuit diagram for electrically connecting a conventional photoelectric separation type smoke sensor.

[Explanation of symbols]

 1 Light Transmitting Section 2 Light Receiving Section 21 Photodiode 22 Light Receiving / Amplifying Circuit 23 Sample Hold Circuit 25 Sending Circuit 27 Constant Voltage Circuit 27a Positive Power Supply Line 27b Negative Power Supply Line 30 Fire Discriminating Means 46 Switch Control Means

Claims (1)

[Claims] 1. A light emitting section, which is provided so as to be separated and opposed to each other, and a light receiving section. The light transmitting section comprises a smoke detecting light emitting element for emitting light and a light emission control circuit for controlling light emission of the light emitting element. The light-receiving unit includes a light-receiving element for smoke detection that receives light from the light-emitting element, a light-receiving amplifier circuit that amplifies a light-receiving output of the light-receiving element,
Fire discrimination means for discriminating whether or not there is a fire based on the light reception output amplified by the light reception amplification circuit, a constant voltage circuit for supplying drive power to the light reception amplification circuit and fire discrimination means, and a constant light emission control signal for the light emission control circuit A sending circuit that sends in a cycle, a switching element that opens and closes a power supply line that connects the constant voltage circuit and the light receiving and amplifying circuit based on an ON / OFF signal, and a light emission control signal sent from the sending circuit, and emits light. A photoelectric separated smoke detector, comprising: a switch control means for outputting an ON signal to a switching element during a period slightly longer than the control signal output period.