JPH0445112Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a photoelectric separation type sensor that detects fire at an early stage by detecting attenuation of light due to smoke.

[Conventional technology]

In a dimming type smoke detector, a light emitter and a light receiver are arranged at a predetermined distance, and when smoke enters between them, the attenuation of light due to the smoke is detected to detect a fire.In general, the luminous flux of the emitter is Since a sensor that spreads out at an angle of several degrees is used, the received light level during monitoring varies depending on the distance between the emitter and receiver, and therefore it was necessary to adjust the received light level depending on the installation location. .

Generally, these adjustments were made by bringing a measuring device to the installation location and connecting it to a designated terminal on the light receiver. Utility Model Application Laid-open No. 192090/1983 has proposed a device equipped with three lamps that indicate whether the gain is too high, too low, or is at an appropriate value.

[Problem that the invention attempts to solve]

The conventional type described above requires three lamps, which are completely unnecessary after adjustment, and after installation, there is a possibility that the optical axis may shift due to vibration or other factors.
Another problem was that it was not possible to display dirt on the optical system.

[Means for solving problems]

This invention consists of a light emitter having a light emitting element that lights up in pulses, a light receiver having a light receiving element located a predetermined distance from the light emitter, and a voltage holding circuit that maintains the light reception level of the light receiving element for a long time. After adjusting the light receiving level in a state where there is no smoke between the emitter and receiver using the level adjustment means that adjusts the light receiving level of the light receiving element, the light receiving level of the light receiving element and the output of the voltage holding circuit are compared, and the difference is determined to be a predetermined value. In a photoelectric separation type sensor that issues an alarm when a certain value is reached, there is a first criterion for determining the level of received light having a predetermined range, and a first criterion that includes the first criterion. The judgment is made by comparing the second judgment standard for fire monitoring, which has a wider range than A level judgment circuit that generates different outputs in three ways: below the lower limit of the reference range, within the range, and above the upper limit of the range, and a level that individually displays each different output generated by this level judgment circuit. an indicator light, a changeover switch that switches the judgment criterion of the level judgment circuit to the first judgment standard or the second judgment standard, and switches the judged input of the level judgment circuit to the light reception level of the light receiving element or the output of the voltage holding circuit; By providing this, the above problems are solved.

[Effect]

By using such means, completion of the light receiving level adjustment can be confirmed by the lighting of the two level indicator lights, and it is also possible to confirm that the optical axis has shifted over a long period of time due to vibrations, etc. during normal monitoring after adjustment. can also be displayed by the same lamp.

〔Example〕

Next, one embodiment of this invention will be explained in detail with reference to the drawings shown below.

Figure 1 shows the circuit diagram of the emitter of the photoelectric separation type sensor, Figure 2 shows the circuit diagram of the receiver, and Figure 3 is a diagram for explaining the operation of each part in Figures 1 and 2. Show time chart.

FIG. 1 is a block diagram of a projector 1, in which the output of a short pulse oscillator 11 is modulated by a long pulse oscillator 12 via an electronic switch 13, an amplifier 14 that amplifies this modulated wave, and an amplifier 14 that amplifies this modulated wave. The light emitting element 15 is pulse-lit. Note that the output waveform of this light emitting element 15 is
Shown in Figure A.

FIG. 2 shows a circuit diagram of the light receiver 2. In the figure, the light receiving element 20 is connected in series between the variable resistor R for adjusting the light receiving level and the positive and negative power supplies, and the slider of the variable resistor R is connected in series. Amplifier 2 via capacitor C
1 is applied. The output of the amplifier 21 passes through a bandpass filter 22, a rectifying and smoothing circuit 23, and anti-interference diodes _D1 and _D2 , and then a first voltage holding circuit 25 which has a relatively short discharge time constant and holds the applied voltage for only a short time. , are applied to the second voltage holding circuit 24 that holds the applied voltage at approximately the peak value for a long time, and these voltage holding circuits 24, 2
5 compensates for secular changes such as dirt on the projecting and receiving surfaces.

The output of each voltage holding circuit 24, 25 is applied to the gate electrode of the thyristor SCR via a comparator 26. Note that a relay 27 is connected to the anode of this thyristor SCR, and a thyristor recovery diode _D3 is connected in series to the cathode and connected between the positive and negative power supplies. Restoration of the thyristor SCR is carried out by temporarily shorting it by means of a changeover switch _S4 connected between the gate and earth.

28 is a level determination circuit, which includes voltage dividing resistors r ₁ , r ₂ , r ₃ , r ₄ , connected in series between the positive and negative power supplies.
r ₅ and the rotor S ₁ of the changeover switch SW from each connection point,
It consists of a comparator 30 for high level determination and a comparator 29 for low level determination, which are connected to each other via _S2 , and each comparator 29,
The other input terminal of the switch 30 is connected to the second voltage holding circuit 24, and is also connected to the negative terminal of the power supply via the rotor S ₃ of the changeover switch SW and the resistor r ₀ . In addition, each rotor S ₁ of the changeover switch SW
S ₄ shall be switched in conjunction with each other.

Each comparator 2 included in the level determination circuit 28
The outputs of 9 and 30 are AND gates 31 and 3, respectively.
applied to one input terminal of 2, and this AND
The other input terminal of the gate is connected to the output side of the rectifying and smoothing circuit 23.

The output of each comparator 29, 30 is further
The output is applied to the NOR gate 33, and the output is applied to the AND gate 3 via interference prevention diodes _D4 and _D5 .
1 and 32. The output of the AND gate 32 is sent to the high level indicator _L1 , and also to the AND gate 32.
The outputs of the gates 31 are respectively connected to low level indicator lights _L2 .

During normal fire monitoring, the changeover switch
Each rotor S ₁ to _{S 4} of SW is set at a fixed position shown as fixed on the drawing. In normal times, the first
The output of the second voltage holding circuit 25 is always higher than the output of the second voltage holding circuit 24, and the comparator 2
No alarm signal is issued from 6.

Smoke enters between the emitter and receiver 1 and 2, and the receiver element 2
When the output of 0 decreases, each voltage holding circuit 24, 2
5 is inverted, an alarm signal is output from the comparator 26, the thyristor SCR is turned on, and the relay 27 is driven.

To adjust the level when installing such a photoelectric separation type sensor, set the changeover switch SW to the position shown by the solid line in the figure, and set the input gate of the comparator of the level judgment circuit 28 to the first judgment criterion, that is, Set in a narrow range consisting of the connection point of voltage division resistors r ₂ and r ₃ and the connection point of voltage division resistors r ₃ and r ₄ . With this setting, the variable resistor R
Make it variable. At this time, the second voltage holding circuit 24
In this case, a resistor r ₀ is connected to the negative side of the power supply via the changeover switch SW S ₃ , thereby functioning equivalently to the first voltage holding circuit 25 .

When the received light level is higher than the specified value, there is an output from the comparator 30, and the high level indicator lamp _L1 is turned on via the AND gate 32 with the cycle and waveform output shown in FIG. 3B.

If the received light level is lower than the specified value, the low level indicator lamp _L2 is lit in the same way.

When the received light level falls within a predetermined value by adjusting the variable resistor R, both comparators 2
Both outputs of 9 and 30 disappear, and as a result,
An output is generated from the NOR gate 33 and applied to one gate of the AND gates 31 and 32, respectively.
Both level indicator lights L ₁ and L ₂ light up. Therefore, it is sufficient to confirm that the two level indicator lights L ₁ and L ₂ are lit to complete the adjustment.

After the adjustment is completed, to return to the monitoring state, it is sufficient to set the changeover switch SW to the normal position. It is set in a wide range consisting of the connection point of resistors r ₁ and r ₂ and the connection point of voltage dividing resistors r ₄ and r ₅ .

In addition, if the changeover switch SW is set to the normal position,
The output of NOR gate 33 is AND gate 31, 32
Therefore, the two level indicator lights L ₁ and L ₂ that were both lit when the adjustment was completed are turned off. This confirms that the changeover switch SW has been returned to its home position in the monitored state, and the two level indicator lights also function as switch warning lights to alert you if you forget to return the changeover switch SW to its home position. It will be held together.

Under such monitoring conditions, for example, if the optical axis changes slightly over a long period of time, whether the change is in the direction of increasing or decreasing the received light level, if it falls outside the second judgment criterion, Either the level indicator L ₁ or L ₂ lights up, and this can be confirmed and identified.

Similarly, the low level indicator light _L2 lights up to detect and confirm the aging of the optical system due to dirt, etc.

[Effect of idea]

The photoelectric separation type sensor of this invention requires only two level indicator lights to be used when adjusting the level as described above, and furthermore, this indicator light can be used if the optical axis is misaligned, the optical system is dirty, or the switch warning light is detected. It has the effect of being able to be used for both purposes.

[Brief explanation of the drawing]

The drawings show an embodiment of the photoelectric separation type sensor of this invention, and FIG. 1 is a circuit diagram of the emitter, FIG. 2 is a circuit diagram of the receiver, and FIG. A time chart is shown to explain the operation. 1... Emitter, 2... Light receiver, 11, 12...
Oscillator, 15... light emitting element, 20... light receiving element,
24, 25...Voltage holding circuit, 26...Comparator, 28...Level judgment circuit, SW...Changing switch, _L1 , _L2 ...Level indicator light.

Claims (1)

[Scope of utility model registration request] It consists of a light emitter having a light emitting element that lights up in a pulsed manner, a light receiver having a light receiving element located at a predetermined distance from the light emitter, and a voltage holding circuit that maintains the light reception level of the light receiving element for a long period of time. After adjusting the light receiving level in a state where there is no smoke between the emitter and receiver using the level adjusting means, the light receiving level of the light receiving element is compared with the output of the voltage holding circuit, and the difference is determined. In a photoelectric separation type sensor that issues an alarm when a predetermined value is reached, a first judgment criterion for determining the received light level having a predetermined range, and a first judgment criterion that includes the first judgment criterion. A second judgment standard for fire monitoring having a wider range than the standard is provided, and the first judgment standard and the light reception level of the light receiving element are set,
Alternatively, the second judgment criterion and the output of the voltage holding circuit are compared, and level judgment is made to generate different outputs in three ways: below the lower limit of the range of the judgment criterion, within the range, and above the upper limit of the range. a circuit, a level indicator lamp that individually displays each different output generated by the level judgment circuit, and a judgment criterion of the level judgment circuit that is set to the first judgment criterion or the second judgment criterion.
1. A photoelectric separation type sensor, comprising: a changeover switch for switching the judgment standard of the level judgment circuit to the light receiving level of the light receiving element or the output of the voltage holding circuit as the judged input of the level judgment circuit.