JP2583529Y2 - Fire detector - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fire detector of a fire alarm system.

[0002]

2. Description of the Related Art Various types of sensors have been used in fire alarm systems. For example, a constant-temperature heat sensor that detects a rise in the temperature of the installation location and generates a detection signal when the temperature rises above a predetermined temperature, and detects a rise rate of the temperature of the installation location and exceeds the predetermined rise rate Differential heat sensor that generates a detection signal when it is detected, Ion smoke detector that detects the concentration of smoke at the installation location and generates a detection signal when the concentration exceeds a predetermined level, Scattered light smoke detection A light detector or a dimmable smoke detector is used. Which sensor is used for each installation location is determined in consideration of the environment of the installation location.
For example, it is determined that a constant temperature type heat sensor is used in a place where fire is handled, such as a kitchen, and a differential type heat sensor or a scattered light type smoke sensor is used in a general living room. In addition, the detection sensitivity of each sensor is set so that the fire can be accurately detected without any false or false information at each installation location.
It is determined in consideration of the usage situation of the installation location.

[0003]

However, even if the sensors to be installed and their sensitivities are determined as described above, a satisfactory fire alarm system has not been obtained considerably. It was particularly difficult to determine the detection sensitivity. For an appropriate detection sensitivity, setting a lower sensitivity setting results in unreporting, while setting a higher sensitivity setting results in false alarms, but the detection sensitivity that is appropriate changes in accordance with the use condition of the installation location.
For example, a constant-temperature heat sensor having an appropriate detection sensitivity in an unused kitchen may generate a detection signal when fire is used in the vicinity thereof. Further, a differential type heat sensor having an appropriate detection sensitivity in a normal living room in normal times may generate a detection signal due to a rapid temperature rise due to the start of operation of a heating device.

[0004]

SUMMARY OF THE INVENTION A fire detector according to the present invention has a variable fire detection sensitivity and takes in a contact output that is opened and closed according to the use condition of equipment installed in the same installation location, and the above equipment is used. In such a case, the detection sensitivity of the fire is changed to a lower value, thereby solving the above problem.

[0005]

With the above configuration, the fire detection sensitivity of the fire detector is changed and set to a sensitivity in consideration of a fire-like phenomenon generated from a device installed in the vicinity.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.
FIG. 1 is an external view showing a connection state of a fire detector according to an embodiment of the present invention. This fire detector is a constant temperature heat detector installed in a kitchen. This constant temperature heat sensor 1
The thermistor 2 is used as a fire detection unit. A contact output that is opened and closed according to the usage state of a gas stove 3 used in a kitchen is taken in via a line 4 into a constant temperature heat sensor 1 installed on a ceiling surface or the like. This gas stove 3
The output of a contact that opens and closes in conjunction with the ignition plug 5 of the gas stove 3 can be used as the contact output that is opened and closed according to the usage condition of the gas stove. The detection signal of the constant temperature heat sensor 1 is sent to a fire receiver (not shown) via the line 6.

FIG. 1 is a circuit diagram showing the embodiment of FIG. 1 in more detail, with a part of FIG. 2 being a block diagram. The constant temperature heat detector 1 includes a thermistor 2 and resistors 7, 8, and 9. A bridge circuit, a differential amplifier 10 for obtaining an output of the bridge circuit, and a threshold circuit 11 with a threshold changing function for generating a detection signal by comparing the output of the differential amplifier 10 with a predetermined threshold. I have. That is, in the constant temperature heat sensor 1, the detection sensitivity of the fire is made variable by changing the threshold of the threshold circuit 11. The gas stove 3 is provided with a contact 12 that opens and closes in conjunction with the ignition plug 5, and the contact output is input to the threshold change terminal 13 of the threshold circuit 11 via the line 4.

[0008] The constant-temperature heat sensor 1 constructed as described above.
In the situation where the gas stove 3 is not used, the threshold of the threshold circuit 11 is set low and the fire detection sensitivity is set high because there is no output from the contact 12.
That is, when the gas stove is not used in the kitchen, there is no fire-like phenomenon that is considered to be generated from the gas stove, so that the fire detection sensitivity is set to a high value so that a false alarm does not occur. Further, in the situation where the gas stove 3 is used, the threshold of the threshold circuit 11 is set high because the output of the contact 12 is present, and the fire detection sensitivity is set low. That is, when a gas stove is used in a kitchen, a phenomenon similar to a fire which is considered to occur from the gas stove occurs, so that the detection sensitivity of the fire is set to be low so that false alarm does not occur.

Next, another embodiment according to the present invention is shown in FIG.

FIG. 3 is a circuit diagram showing a block diagram of a part of a differential heat sensor provided in a living room in which a heating device is installed. The differential heat sensor 30 has one heat capacity. A bridge circuit including two thermistors 31 and 32 and resistors 33 and 34 in which the rate of change of the resistance value is made different by increasing the resistance value, a differential amplifier 35 for obtaining an output of the bridge circuit;
Further, a threshold circuit 36 with a threshold changing function for comparing the output of the differential amplifier 35 with a predetermined threshold to generate a detection signal
And a timed output circuit 37 for inputting a contact output that is opened or closed depending on the use state of the device to a threshold value changing terminal of the threshold circuit 36 for a certain period. That is, in the differential heat sensor 30, the detection sensitivity of the fire is made variable by changing the threshold of the threshold circuit 36,
The period during which the detection sensitivity of the fire is changed after the contact output that is opened / closed according to the use condition of the device is input is set as a fixed period by the timed output circuit 37. The heating device 38 is provided with a contact 39 that opens and closes in conjunction with the start of operation.
The contact output is supplied to the timed output circuit 37 via the line 40.
Is input to the input terminal 41.

The differential heat sensor 30 constructed as described above
, When the heating device 38 starts operating, an output is generated at the contact point 39 and the output is input to the input terminal 41 of the timed output circuit 37. Then, the timed output circuit 37 continues to send output to the threshold changing terminal of the threshold circuit 36 for a certain period, for example, a period of about thirty minutes required for the resistance values of the thermistors 31 and 32 to become substantially the same. With this output, the threshold of the threshold circuit 36 is set high, and the fire detection sensitivity is set low. That is, for a certain period immediately after the operation of the heating device is started, the detection sensitivity of the fire is set to be low, so that there is no false alarm caused by a fire-like phenomenon considered to be generated from the heating device. Then, after a certain period in which the resistance values of both thermistors 31 and 32 become substantially the same and a fire-like phenomenon does not occur depending on the heating device, the output from the timed output circuit 37 stops and the threshold value of the threshold circuit 36 Is set low, and the fire detection sensitivity is set high to prevent a false alarm from occurring.

[0012] In addition to the above embodiments, if a fire detector having a microcomputer mounted inside it has recently been produced in large numbers as a fire detector, the change of the threshold value and the period of the change can be made. Of course, it can be handled by software.

[0013]

[Effects of the Invention] As described above, the fire detector according to the present invention makes the detection sensitivity of fire variable, captures the contact output that is opened and closed according to the usage status of the cooking equipment installed in the same installation location, and When used, fire detection sensitivity can be changed to a lower level. Therefore, even if a constant-temperature heat sensor is set as an appropriate detection sensitivity in an unused kitchen, the detection sensitivity is automatically switched to low sensitivity when fire such as a gas stove is used in the vicinity. Thus, false alarm can be prevented beforehand. When fire such as a gas stove is not used, a false alarm can be prevented by detecting a fire with appropriate detection sensitivity.

Furthermore, the detection sensitivity in addition to the above constituent device
A timed output circuit is provided for changing the operation for a certain period immediately after the start of the operation . Thereby, for example, even if a differential type heat sensor set as an appropriate detection sensitivity in a normal living room in normal times receives a sudden temperature rise due to the start of operation of the heating device, the detection sensitivity is automatically fixed. By switching to the low sensitivity for the period, false alarm can be prevented beforehand. And, when the heating device is not used, or at the time of operation other than immediately after the start of the operation of the heating device,
By detecting a fire with appropriate detection sensitivity, a false alarm can be prevented.

[Brief description of the drawings]

FIG. 1 is an external view showing a connection state of a fire detector according to an embodiment of the present invention.

FIG. 2 is a circuit diagram in which a part is shown as a block in order to show the embodiment of FIG. 1 in further detail.

FIG. 3 is a circuit diagram partially showing a connection state of a fire detector according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Constant temperature heat sensor 3 Gas stove 4 Line 5 Spark plug 6 Line 10 Differential amplifier 11 Threshold circuit 12 Contact 30 Differential heat sensor 35 Differential amplifier 36 Threshold circuit 37 Time limit output circuit 38 Heating equipment 39 Contact 40 Line

Claims (3)

(57) [Scope of request for utility model registration] When the cooking appliance is in use, the detection sensitivity of the fire is made variable, and a contact output that is opened and closed according to the use condition of the cooking appliance installed in the same installation location is taken in.
Is a fire detector that changes the fire detection sensitivity to a lower level . 2. The method according to claim 1, wherein the detection sensitivity of the fire is variable, and a contact output that is opened and closed according to the use condition of the equipment installed at the same installation location is taken in. The detection sensitivity is set for a certain period immediately after the operation of the equipment is started. A fire detector that changes the fire detection sensitivity to a lower level . 3. The fire detector according to claim 2, wherein the fire detector is a differential heat detector, and the equipment installed at the same installation location is a heating equipment.