JPH051415B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] FIELD OF THE INVENTION The present invention relates to smoke detection devices.

[Prior art]

For example, the smoke produced when a passenger smokes inside a vehicle, even at low concentrations, pollutes the air inside the vehicle and causes discomfort to other passengers, especially those who dislike smoking. This problem becomes more serious as the vehicle interior becomes narrower.

In order to cope with this problem, the present invention aims to enable a smoke detection device to accurately detect smoke generated from cigarettes and various other smoke generating sources regardless of its concentration.

[Means to solve the problem]

In order to solve the above problems, the structural features of the present invention include a casing in which a smoke inflow space is formed so as to block the incidence of external light; a light emitting element that is arranged to emit light toward the same inflow space; and a first light receiving element that is arranged to directly receive light from the light emitting element and generates the amount of light received from the light emitting element as a light reception signal. and when receiving light from the light emitting element that is arranged in isolation so as not to directly receive light from the light emitting element and reflected by the inner surface of the casing and the smoke in the inflow space, the amount of light received is determined. a second light-receiving element that generates a signal; and a detection means that detects a difference between the value of the light-receiving signal from the first light-receiving element and the value of the light-receiving signal from the second light-receiving element and generates this as a detection signal. A smoke detection device comprising: a light amount adjusting means disposed between the light emitting element and the first light receiving element to adjust the amount of light from the light emitting element to the first light receiving element; The light amount adjusting means controls the light emitting element from the first light receiving element so that the value of the light receiving signal from the first light receiving element becomes equal to the value of the light receiving signal generated from the second light receiving element when no smoke exists in the inflow space. The light amount to the light receiving element is adjusted, and the first light receiving element generates the light amount adjusted by the light amount adjusting means as a light reception signal.

[Function and effect of the invention]

In the present invention configured in this way, the value of the light reception signal from the first light receiving element is made equal to the value of the light reception signal generated from the second light receiving element when no smoke exists in the inflow space. The amount of light from the light emitting element to the first light receiving element is adjusted by the light amount adjusting means, and the first light receiving element generates the amount of light adjusted by the light amount adjusting means as a light reception signal. Even if the concentration of the smoke flowing into the inflow space is low, the value of the light reception signal from the second light receiving element is equal to the amount of light reflected by the smoke from the light emitting element.
This will surely increase the value of the light reception signal from the first light receiving element, that is, the value corresponding to the amount of light adjusted by the light amount adjustment means.

In such a case, the first light receiving element is adjusted by adjusting the amount of light from the light emitting element to the first light receiving element by the light amount adjusting means disposed between the light emitting element and the first light receiving element. Since the value of the light reception signal from the second light receiving element is made equal to the value of the light reception signal generated from the second light receiving element when no smoke exists in the inflow space, the value of the light reception signal generated from the second light receiving element when no smoke exists in the inflow space is Adjustments can be made with high accuracy to equalize the values of the respective light reception signals from the first and second light receiving elements. As a result, even if the concentration of smoke is low as described above, the detection means can accurately detect the difference between the value of the light reception signal from the first light receiving element and the value of the light reception signal from the second light receiving element. It can be realized. Further, if a display means such as a buzzer circuit is driven based on a detection signal generated from the detection means in response to such detection, the occurrence of smoke can be displayed regardless of its concentration, and as a result, it is possible to display the occurrence of smoke regardless of its concentration. Necessary measures can be taken in a timely manner. Further, by driving various devices having a function of removing smoke based on the above-mentioned detection signal, generated smoke can be automatically removed in a timely manner. Also,
The above-mentioned effects are particularly remarkable when the present invention is applied to the interior of a vehicle.

〔Example〕

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings. Fig. 1 and Fig. 2 show an example of a smoke detection device according to the present invention applied to a vehicle. It is composed of a smoke sensor 10 disposed at a suitable location in the cabin of a vehicle, and an electric circuit 20 connected to this smoke sensor 10. The smoke sensor 10 has a casing 11 made of a material that does not transmit light, and the casing 11 is attached at its bottom wall 11a to a part of the interior wall of the vehicle. A pair of inflow ports 11d and 11e are formed opposite each other in the upper portions of the left and right side walls 11b and 11c shown in FIG. 1 of the casing 11. Cigarette smoke flows into the inflow space A (see Figure 1). Note that each of the inlets 11d and 11e has a looper shape to block disturbance light from entering the casing 10.

Inside the casing 11, a base body 12 made of a material that does not transmit light is provided at the first inlet port 11d, 11e.
It is stored at the bottom in the figure, and this base 1
A recess 12a is formed in the center of the upper surface of the casing 11 so as to open toward the inner surface of the upper wall 11f of the casing 11 through the inflow space A. On the right side of the base body 12 in FIG.
A light emitting device 13 is fitted into the insertion hole 12b with its light emitting surface facing into the recess 12a. In such a case, the inclination angle of the right side wall of the recess 12a, that is, the central axis of the insertion hole 12b, with respect to the upper wall 11f of the casing 11 is such that when the light emitter 13 emits light from its entire light emitting surface, this light is In the figure, it is determined to reach the entire left side wall and the surface portion of the upper wall 11f facing the recess 12a.
Note that the light emitter 13 has a built-in near-infrared light emitting diode, and this near-infrared light emitting diode is intermittently electrically connected in response to a series of drive pulses generated from a drive circuit (not shown), and is intermittently emitted from the light emitting surface. Emits light.

An insertion hole 12c that opens upward in the figure through the bottom wall of the recess 12a is formed in the center of the base 12, and a light receiver 14 is inserted into the insertion hole 12c.
is fitted with its light-receiving surface facing into the recess 12a. The light receiver 14 has a built-in photodiode 14a (see FIG. 2), and this photodiode 14a receives light from the light emitter 13 reflected by the inner surface of the upper wall 11f and/or the cigarette smoke present in the inlet space A. When light is received through the light-receiving surface, it is intermittently conductive and the amount of received light is generated as an intermittent light-receiving current. In such a case, the light-receiving surface of the hole receiver 14 is connected to the generator 13 by the inner peripheral wall of each insertion hole 12b, 12c.
Since the light receiver 14 is isolated from the light emitting surface of the light emitter 13, the light receiver 14 does not receive direct light from the light emitter 13.

On the left side of the base body 12 in FIG.
is bored in the lateral direction, and a light receiver 15 is fitted into this insertion hole 12d with its light receiving surface facing the bottom wall of the insertion hole 12d. In addition, the base 12
The light amount adjustment hole 12e is located on the left side of the figure, and the light amount adjustment hole 12e is connected to the insertion hole 1.
2d and the recess 12a, and one end of this light amount adjustment hole 12e is connected to the insertion hole 12.
d through the center of its bottom wall, and the other end of the light amount adjustment hole 12e opens into the recess 12a through the lower part of its left side wall. The light receiver 15 has a built-in photodiode 15a (see FIG. 2),
The photodiode 15a receives direct light from the light emitter 13 through the recess 12a and the light amount adjustment hole 12e on its light receiving surface, and is intermittently conducted to generate the amount of received light as an intermittent light receiving current. In such a case, the inner diameter of the light amount adjustment hole 12e is such that the amount of light received by the light receiver 15 through the light amount adjustment hole 12e is determined by the amount of light received by the light receiver 15 through the light amount adjustment hole 12e.
The length of the light amount adjustment hole 12e is selected to be somewhat larger than the amount of light reflected from the light emitter 13 that is reflected by the upper wall 11f and received by the light receiver 14 when there is no smoke inside. Upper wall 1
It is selected so as to be able to block the reflected light from 1f from entering the light receiver 15. Note that both photodiodes 14a and 15a have the same characteristics.

In addition, at the corner portion of the left side of the base 12 in the drawing,
The screw hole 12f is connected to the light amount adjustment hole 1 from the top surface of the base 12.
An adjustment screw 16 is provided in the screw hole 12f so as to open through the peripheral wall portion of the hole 2e.
is adjustable and screwed on. By finely adjusting the adjustment screw 16, the amount of light passing through the light amount adjustment hole 12e (that is, the amount of light received by the light receiver 15) is adjusted to the upper wall where the light receiving element 14 receives light when there is no smoke in the inflow space A. It is made to precisely match the amount of reflected light from 11f.

The electric circuit 20 includes a pair of resistors 2 connected in series with each other to form a voltage divider, as shown in FIG.
1 and 22, the resistor 22 cooperates with the resistor 21 to divide the power supply voltage from the DC power supply B of the vehicle, and generates this divided voltage from a common connection terminal with the resistor 21. The photodiode 14a connects both resistors 21 and 22 via a resistor 23 at its anode.
The photodiode 15a is connected to the common connection terminal of the DC power supply B and the resistor 21 at its cathode, forming a closed circuit together with both resistors 21 and 23, while the photodiode 15a is connected at its anode to the common connection terminal of the DC power supply B and the resistor 21. It is grounded and connected at its cathode to the anode of the photodiode 14a, forming a closed circuit with both resistors 22 and 23.

The operational amplifier 25 connects both photodiodes 14a, 1 through a capacitor 24 at its non-inverting input terminal.
5a, and the inverting input terminal of the operational amplifier 25 is grounded through a resistor 25a, and connected to the operational amplifier 2 through a resistor 25b.
It is connected to the output terminal of 5. capacitor 24
applies the common connection terminal of both photodiodes 14a, 15a to the operational amplifier 25 as a field voltage. Therefore, the operational amplifier 25 has both resistors 25
The filter voltage from the capacitor 24 is amplified with an amplification factor determined by a and 25b, and this is generated as an amplified voltage. Note that the reference numeral 25c indicates a resistor for input impedance matching of the operational amplifier 25, and the reference numeral 26 indicates a resistor.

In this embodiment configured as above, when there is no cigarette smoke in the inflow space A, the light receiver 1
4 receives intermittent light from the light emitter 13 reflected by the inner surface of the upper wall 11f of the casing 11, the photodiode 14a conducts while being reverse biased by the terminal voltage of the resistor 21, corresponding to the amount of light received. A light-receiving current is generated, and both resistors 21 and 23
to flow into. On the other hand, when the light receiver 15 directly receives the intermittent light from the light emitter 13 through the recess 12a and the light amount adjustment hole 12e, the photodiode 15a becomes conductive while being reverse biased by the divided voltage from the resistor 22, and the amount of received light increases. A light receiving current corresponding to the current is generated and flows into both resistors 23 and 22. For this reason, resistance 2
The light-receiving currents from both photodiodes 14a and 15a flowing through photodiodes 14a and 15a cancel each other out, and the voltage appearing at the common connection terminal of both photodiodes 14a and 15a is maintained equal to the divided voltage from resistor 22. As a result, the filter voltage generated from the capacitor 24 becomes zero as the divided voltage is cut off by the capacitor 24, and the amplified voltage generated from the operational amplifier 25 becomes zero. This means that the device of the present invention has detected that there is no cigarette smoke in the cabin of the vehicle.

When the occupant of the vehicle smokes in such a state, if the smoke from the cigarette passes through the inlet 11d or 11e of the casing 11 and flows into the inlet space A, the concentration of smoke in the inlet space A will change. Accordingly, a part of the intermittent light from the light emitter 13 is reflected by the smoke and received by the light receiver 14, and the remaining part of the intermittent light passes through the smoke and reaches the upper wall 11.
The light is reflected by the inner surface of f, passes through the smoke again, and is received by the light receiver 14. Then, the photodiode 14a detects the amount of light reflected from the smoke and the upper wall 11.
A light receiving current corresponding to the sum of the amount of light reflected from the inner surface of f is generated and flows into both resistors 21 and 23. In such a case, even if the intermittent light from the light emitter 13 is partially absorbed by the smoke in the inflow space A, the smoke in the inflow space A also flows into the lower part of the recess 12a, so the amount of light from the light emitter 13 is reduced. The direct intermittent light directed toward the adjustment hole 12e is also absorbed by the smoke in the recess 12a at approximately the same light absorption rate as the smoke in the inflow space A. This means that even if smoke is present in the casing 11, the amount of light received by the light receiver 15 and the amount of light received with respect to the light reflected from the inner surface of the upper wall 11f of the light receiver 14 are always maintained approximately equal. means.

However, as mentioned above, the photodiode 1
When the light receiving current from the photodiode 15a flows into the resistor 23, an intermittent voltage corresponding to the difference between this light receiving current and the light receiving current from the photodiode 15a flows into the resistor 22.
Both photodiodes 1 are superimposed on the divided voltage from
A pulsating voltage is generated at the common connection terminal of 4a and 15a. Then, the capacitor 24 removes the DC component (i.e., the divided voltage) from the pulsating voltage and generates the remaining portion as a filter voltage, and in response, the operational amplifier 25 amplifies and amplifies the filter voltage. Generated as voltage. This means that the device of the present invention has detected that cigarette smoke has been generated in the cabin of the vehicle. In such a case, the amount of light received by the light receiver 15 can be adjusted by adjusting the light from the light emitter 13 to the light receiver 15 by adjusting the adjusting screw 16 disposed between the light emitter 13 and the light receiver 15. Since the amount of light received by the light receiver 14 is set to be equal to the amount of light received by the light receiver 14 when there is no smoke in the inflow space A, the amount of light received by both light receivers 14 and 1 when there is no smoke in the inflow space A is
Adjustments can be made with high precision to make the amounts of received light equal to each other. As a result, even if the smoke density is low, the amplified voltage from the operational amplifier 25 can be obtained as a highly accurate value. In other words, even if the concentration of cigarette smoke is low, the difference in the amount of light received by both the light receivers 14 and 15 is reliably generated with high precision, so even low concentration smoke can be detected with high precision.

In the above description of the operation, since both photodiodes 14a and 15a have the same characteristics, each of these photodiodes 14a and 15a
a undergoes similar characteristic changes in response to changes in ambient temperature and changes in characteristics over time, and as a result, regardless of the presence or absence of smoke within the casing 11, the amount of light received by the photodiode 15a and that of the casing 11 are The amount of light received by the photodiode 14a with respect to the light reflected from the inner surface of the upper wall 11f can always be maintained at approximately the same value. Therefore, the detection results of the device of the present invention include changes in ambient temperature and the detection results of each photodiode 14.
Errors due to changes in characteristics of a and 15a over time do not occur.

Furthermore, in the above embodiment, an example was described in which the device of the present invention was adopted for detecting cigarette smoke inside a vehicle, but the present invention is not limited to this. It goes without saying that the device of the present invention can also be applied.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a smoke sensor constituting the device of the present invention, and FIG. 2 is an electrical circuit diagram for the smoke sensor. Explanation of symbols A...Inflow space, 11...Casing, 11f...Top wall, 12...Base, 12e...Light amount adjustment hole, 12f...Screw hole, 13...Light emitter, 14,1
5... Light receiver, 16... Adjustment screw, 20... Electric circuit.

Claims (1)

[Scope of Claims] 1. A casing having a smoke inflow space formed therein so as to block the incidence of external light, and a smoke inflow space disposed inside the casing so as to face each other through the inflow space. a light-emitting element that emits light toward the light-emitting element; a first light-receiving element that is arranged to directly receive light from the light-emitting element and generates the amount of light received from the light-emitting element as a light reception signal; a second light receiving element which is arranged in isolation so as not to directly receive light from the light emitting element and which, when receiving light from the light emitting element reflected by the inner surface of the casing and the smoke in the inflow space, generates the amount of received light as a light receiving signal; and a detection means for detecting the difference between the value of the light reception signal from the first light receiving element and the value of the light reception signal from the second light receiving element and generating this as a detection signal, A light amount adjusting means is provided between the light emitting element and the first light receiving element to adjust the amount of light from the light emitting element to the first light receiving element, Adjusting the amount of light from the light emitting element to the first light receiving element by the light amount adjusting means so that the value is equal to the value of the light reception signal generated from the second light receiving element when there is no smoke in the inflow space. , and the first light receiving element is configured to generate a light amount adjusted by the light amount adjusting means as a light reception signal.