CN111006979B - A circuit and compensation method for environmental compensation of smoke detector - Google Patents

Abstract

The invention belongs to the field of aviation electrical technology, and relates to a circuit and a compensation method for environmental compensation of a smoke detector; including a control circuit, a luminous tube drive circuit, a luminous tube drive adjustment circuit, a luminous tube reference circuit, and a luminous tube acquisition circuit The present invention can effectively reduce the drift of the smoke detector sensitivity caused by environmental factors such as temperature and humidity, reduce the false alarm rate of the smoke detector, and improve the reliability of the product. The method is mainly to adjust the driving current of the light emitting tube according to the change of the response intensity of the reference light receiving tube, so that the light receiving tube maintains an equivalent response intensity to the fire smoke particles. The invention is stable, reliable, simple and easy to implement.

Description

A circuit and compensation method for environmental compensation of smoke detector

technical field

The invention belongs to the field of aviation electrical technology, and relates to a circuit and a compensation method for environmental compensation of a smoke detector.

Background technique

At present, the fire detection technologies that have been practically applied in engineering are mostly smoke sensing, temperature sensing, smoke-temperature composite or other types of composite. In the field of aircraft, the mainstream of fire detectors is photoelectric smoke detectors. The core structure of this type of smoke detector is a labyrinth component, and the core components are photoelectric tubes. When the environment such as temperature and humidity changes, the characteristics of the above structures and components will change. Furthermore, the sensitivity of the smoke detector drifts. For example, the luminous efficiency of the luminous tube increases at low temperature, and the frost on the photoelectric tube during the process of high temperature to low temperature will reduce the light collection efficiency. The detector outputs false alarms and fault phenomena. Traditional smoke detectors do not compensate for the sensitivity caused by the environment, and cannot meet the requirements of high consistency in the sensitivity of smoke detectors in special fields such as aviation.

Contents of the invention

The object of the present invention is to propose a circuit and method for environmental compensation of smoke detectors for the problem of sensitivity drift of smoke detectors caused by the environment.

The technical solution of the present invention is,

A circuit for environmental compensation of a smoke detector, characterized in that the environmental compensation circuit includes a control circuit, a luminous tube drive circuit, a luminous tube drive adjustment circuit, a luminous tube reference circuit, and a luminous tube acquisition circuit; The tube drive circuit and the light-emitting tube drive adjustment circuit send control signals, and collect the electrical signals of the light-receiving tube reference circuit and the light-emitting tube acquisition circuit; The circuit adjusts the luminous intensity of the luminous tube according to the effective value of the control circuit signal; the luminous tube reference circuit and the luminous tube acquisition circuit are responsible for converting the luminous intensity of the luminous tube into an electrical signal.

The smoke concentration response value of the light receiving tube reference circuit and the light receiving tube acquisition circuit is positively correlated with the change of environmental factors, that is, the change trend of the smoke concentration response value of the two paths is the same as that of the environmental factors; according to the light receiving tube reference circuit and the light receiving tube The change of the smoke concentration response value of the collection circuit is collected, and the current of the driving circuit of the luminous tube is adjusted to keep the equivalent response intensity of the luminous tube to the fire smoke particles.

The smoke concentration response value of the light receiving tube reference circuit is not affected by the external smoke concentration, and the smoke concentration response value of the light receiving tube collection circuit is positively correlated with the smoke concentration;

The light receiving tube reference circuit and the light receiving tube acquisition circuit use photosensitive devices of the same specification;

The smoke concentration response value is calculated by the following calculation formula:

Va＝I*Ka*(M0+M1+M2)+Vb..........................(1)

Varef＝I*Karef*(M0erf+M2erf)+Vbref..........(2)

In the formula, I is the operating current of the luminous tube, M0 and M0ref are the equivalent smoke concentration values of the labyrinth components; M1 is the smoke concentration value in the labyrinth components; M2 and M2ref are the equivalent smoke concentration values caused by the environment except smoke particles ; Ka, Karef are the smoke concentration conversion coefficients of the smoke detector; Vb, Vbref are the system errors brought by the amplifying circuit of the smoke detector.

Under the conditions of said Vb<<Ka(M0+M1+M2), Vbref<<Karef(M0erf+M2erf), (1), (2) can be simplified as

Va＝I*Ka*(M0+M1+M2)..........................(3)

Varef＝I*Karef*(M0erf+M2erf)..........(4)

During use, the Varef is changed by the influence of the labyrinth components and the external environment, and this change will also be applied to Va; in order to compensate for the influence of the external environment on Va, the luminous flux φ1 can be increased by adjusting the operating current I, The light receiving tube maintains an equivalent response intensity to fire smoke particles, thereby ensuring the consistency of the sensitivity of the smoke detector.

A compensation method for a circuit for smoke detector environmental compensation, characterized in that:

a. Place the smoke detector in clean air, record and store the response concentration of the photoelectric tube of the light receiving tube reference circuit and the light receiving tube acquisition circuit as the background value;

b. When the change of the smoke concentration response value of the light receiving tube reference circuit and the light receiving tube acquisition circuit is positively correlated, the driving current of the light emitting tube is adjusted in the opposite direction, and the compensation of the smoke concentration response value of the light receiving tube reference circuit is restored to the background value, and the compensation is completed;

When the smoke concentration response value of the reference circuit of the light receiving tube increases, and the change of the collection circuit of the light receiving tube decreases, the compensation value is 0;

The smoke concentration response value of the reference circuit of the receiving tube remains unchanged, but when the collection circuit of the receiving tube increases or decreases, the compensation value is 0;

When the smoke concentration response value of the reference circuit of the light receiving tube decreases, and when the change of the collection circuit of the light receiving tube increases, the compensation of the smoke concentration response value of the reference circuit of the light receiving tube returns to the background value, and the compensation ends.

Beneficial effects of the present invention:

The invention can effectively reduce the drift of the smoke detector sensitivity caused by environmental factors such as temperature and humidity through the smoke detector environment compensation circuit and compensation method, reduce the false alarm rate of the smoke detector, and improve the reliability of the product. The method is mainly to adjust the driving current of the light emitting tube according to the change of the response intensity of the reference light receiving tube, so that the light receiving tube maintains an equivalent response intensity to the fire smoke particles. The invention is stable, reliable, simple and easy to implement.

Description of drawings

Fig. 1 is a structural block diagram of the environmental compensation circuit of the present invention.

Fig. 2 is a functional block diagram of the environmental compensation circuit of the present invention.

Fig. 3 is the current control regulation signal circuit of the present invention.

Detailed ways

The technical solution of the present invention will be further described below in conjunction with the accompanying drawings.

Fig. 1 is a structural block diagram of the environmental compensation circuit of the present invention. The smoke response value of the smoke detector is mainly affected by the components of the labyrinth, environmental factors, and smoke particles. Because the labyrinth parts cannot be completely black, so that the smoke detector is in clean air, even if the working current I is not equal to zero, the light receiving tube can still receive part of the light, and then converted into M0, M0ref as part of the smoke response value, which is Some of the changes are slow, which can be compensated by identifying slow changes in the response value. The response of smoke particles is the main function of the smoke detector, and the stability of the smoke detector’s response to smoke particles should be ensured. However, since the collection circuits of the light-emitting tube and the light-receiving tube include a part of semiconductor devices, this type of components is relatively sensitive to environmental changes. sensitive. The external environment acts on the luminous tube drive circuit, luminous tube drive adjustment circuit, luminous tube reference circuit, and luminous tube acquisition circuit, thereby affecting Va and Varef. Smoke particles can only enter the interior of the labyrinth, and cannot enter the luminous tube and light collection circuit. The area between the light-receiving tubes of the light-emitting tube reference circuit (the light-emitting tube and the light-receiving tube of the light-receiving tube reference circuit form a closed space) affects the optical path between the light-emitting tube and the light-receiving tube of the light-receiving tube collection circuit , cannot affect the light path between the light-emitting tube and the light-receiving tube of the light-receiving tube reference circuit.

Fig. 2 is a functional block diagram of the environmental compensation circuit of the present invention. The environmental compensation circuit includes a control circuit, a luminous tube drive circuit, a luminous tube drive adjustment circuit, a light receiving tube reference circuit, and a light receiving tube acquisition circuit. The response value of the light receiving tube reference circuit is only affected by the maze components and environmental factors, and is not affected by smoke particles. The light receiving tube collection circuit is affected by the maze components, smoke particles, and environmental factors. The specification of the circuit is the same as that of the semiconductor device used in the collecting circuit of the light receiving tube. The compensation algorithm is as follows:

a. Place the smoke detector in clean air, record and store the response concentration of the photoelectric tube of the light receiving tube reference circuit and the light receiving tube acquisition circuit as the background value;

b. When the change of the smoke concentration response value of the light receiving tube reference circuit and the light receiving tube acquisition circuit is positively correlated, the driving current of the light emitting tube is adjusted in the opposite direction, and the compensation of the smoke concentration response value of the light receiving tube reference circuit is restored to the background value, and the compensation is completed;

When the smoke concentration response value of the reference circuit of the light receiving tube increases, and the change of the collection circuit of the light receiving tube decreases, the compensation value is 0;

The smoke concentration response value of the reference circuit of the receiving tube remains unchanged, but when the collection circuit of the receiving tube increases or decreases, the compensation value is 0;

When the smoke concentration response value of the reference circuit of the light receiving tube decreases, and when the change of the collection circuit of the light receiving tube increases, the compensation of the smoke concentration response value of the reference circuit of the light receiving tube returns to the background value, and the compensation ends.

Fig. 3 is the driving regulation circuit of the luminous tube of the present invention. The adjustment signal passes through R1, R2, R3, R4, and acts on the base of V1 together with Vcc. Due to the filtering effect of C1 and C2, the adjustment signal can be a DC signal or an AC signal. The switch signal is connected to the emitter of V1 through R5. When the switch signal is at a high level, the base voltage of V2 is the sum of the voltage at the base of V1 and V1e-b. When the switch signal is at a high level, the base voltage of V2 is The voltage at the base of V1 is added to V1e-b, and when the switching signal is at low level, the base voltage of V2 is at low level. The adjustment signal is sent by a digital control circuit, so the common type of the adjustment signal is a rectangular wave. When the duty ratio of the adjustment signal increases, the voltage at the base of V1 increases, thereby increasing the current of V2c-e (ie, the operating current I). When the duty cycle of the regulating signal decreases, the voltage of the base of V1 decreases, thereby reducing the current of V2c-e (ie, the operating current I).

The invention can effectively reduce the environmental drift of the sensitivity of the smoke detector, reduce the false alarm rate of the smoke detector, and improve the reliability of the product.

Claims (5)

1. A circuit for smoke detector environmental compensation, characterized in that: comprising a control circuit, a luminous tube drive circuit, a luminous tube drive adjustment circuit, a luminous tube reference circuit, a luminous tube acquisition circuit; The driving circuit and the luminous tube drive adjustment circuit send the control circuit signal, and collect the electrical signal of the luminous tube reference circuit and the luminous tube acquisition circuit; The circuit adjusts the luminous intensity of the luminous tube according to the effective value of the control circuit signal; the luminous tube reference circuit and the luminous tube acquisition circuit are responsible for converting the luminous intensity of the luminous tube into an electrical signal; The smoke concentration response value of the light receiving tube reference circuit and the light receiving tube acquisition circuit is positively correlated with the change of environmental factors, that is, the change trend of the smoke concentration response value of the two channels is the same as that of the environmental factors; according to the light receiving tube reference circuit and the light receiving tube acquisition circuit Changes in the smoke concentration response value, adjust the current of the luminous tube drive circuit, so that the luminous tube maintains the equivalent response intensity to the fire smoke particles; The smoke concentration response value of the reference circuit of the light receiving tube is not affected by the external smoke concentration, and the smoke concentration response value of the light collecting tube collection circuit is positively correlated with the smoke concentration; The external environment acts on the luminescent tube drive circuit, the luminescent tube drive adjustment circuit, the light receiving tube reference circuit, and the light receiving tube acquisition circuit, thereby affecting the smoke concentration response value Va of the light receiving tube acquisition circuit and the smoke concentration response value Varef of the light receiving tube reference circuit , the smoke particles can only enter the interior of the labyrinth components, and cannot enter the area between the light emitting tube and the light receiving tube of the light receiving tube reference circuit. The light emitting tube and the light receiving tube of the light receiving tube reference circuit form a closed space, that is, the The optical path between the light emitting tube and the light receiving tube of the light receiving tube collection circuit is affected, and cannot affect the light path between the light emitting tube and the light receiving tube of the light receiving tube reference circuit; The smoke concentration response value is calculated by the following calculation formula: Va=I*Ka*(M0+M1+M2)+Vb...........................(1) Varef= I*Karef*(M0ref+M2ref)+Vbref..........(2) In the formula, I is the working current of the luminous tube, M0 and M0ref are the equivalent smoke concentration values of the labyrinth components respectively; M1 is the smoke concentration value inside the labyrinth components; M2 and M2ref are the equivalent smoke concentrations caused by the environment except the smoke particles Value; Ka, Karef is the smoke concentration conversion coefficient of the smoke detector, Vb, Vbref is the system error brought by the smoke detector amplifier circuit. 2. A circuit for environmental compensation of smoke detectors according to claim 1, characterized in that: the light receiving tube reference circuit and the light receiving tube acquisition circuit use photosensitive devices of the same specification. 3. A circuit for smoke detector environmental compensation according to claim 1, characterized in that: the conditions of Vb<<Ka(M0+M1+M2), Vbref<<Karef(M0ref+M2ref) Now, (1) and (2) are simplified as Va=I*Ka*(M0+M1+M2)................................(3) Varef=I*Karef*(M0ref+M2ref)...........(4). 4. A circuit for environmental compensation of a smoke detector according to claim 1, characterized in that: during use, the smoke concentration response value Varef of the light receiving tube reference circuit is affected by the labyrinth components and the external environment If there is a change, the change will also be applied to the smoke concentration response value Va of the collection circuit of the light collection tube; in order to compensate the influence of the external environment on the smoke concentration response value Va of the collection circuit of the light collection tube, the luminous flux φ1 is increased by adjusting the working current I , so that the receiving tube maintains an equivalent response intensity to fire smoke particles, thereby ensuring the consistency of the sensitivity of the smoke detector. 5. The compensation method of the circuit of the smoke detector environment compensation according to any one of claims 1-4, characterized in that: a. Place the smoke detector in clean air, record and store the response concentration of the photoelectric tube of the light receiving tube reference circuit and the light receiving tube acquisition circuit as the background value; b. When the change of the smoke concentration response value of the light receiving tube reference circuit and the light receiving tube acquisition circuit is positively correlated, the driving current of the light emitting tube is adjusted in the opposite direction, and the compensation of the smoke concentration response value of the light receiving tube reference circuit is restored to the background value, and the compensation is completed; Or, when the smoke concentration response value of the reference circuit of the light receiving tube increases, and the change of the collection circuit of the light receiving tube decreases, the compensation value is 0; Or, the smoke concentration response value of the reference circuit of the light receiving tube remains unchanged, but when the change of the collection circuit of the light receiving tube increases or decreases, the compensation value is 0; Or, when the response value of the smoke concentration of the reference circuit of the light receiving tube decreases and the change of the collection circuit of the light receiving tube increases, the compensation of the response value of the smoke concentration of the reference circuit of the light receiving tube returns to the background value, and the compensation ends.

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