[0001] This invention relates to a fire detector which is equipped with a sensor detecting
physical quantity of heat, light or smoke and which, in particular, stores the time
when the fire detector has operated and the output of the sensor at that time so that
these stored data may be indicated whenever required later.
[0002] The conventional fire detector of this kind continuously supervises changes in output
level of the above sensor and operates when the predetermined basic level is exceeded.
Therefore, even though one can know by operation of the fire detector that the output
level has exceeded the basic level, it is not possible to know later the actual output
level at that time or the operating time of the detector. Therefore, it has been impossible
to clear up the cause of the false alarm if produced by the fire detector.
[0003] In view of the above, this invention offers a fire detector which is equipped means
to store the time when the fire detector has operated and the output level of the
sensor at that time, and to indicate the stored time and output level at any time
so that these stored data may be confirmed later whenever necessary.
[0004] The following describes an embodiment of this invention with reference to the accompanying
drawings. Shown in Figure 1 are as follows:
a sensor 1 which detects physical quantity of heat, light or smoke. an amplifier 2
which amplifies output of the sensor 1. an A - D converter 3 which converts an analogue
signal showing an output level of the sensor 1 to a digital signal. a clock part 4.
a first indicating part 5 which indicates a present time or a present output level
of the sensor 1 whenever necessary. a second indicating part 6 which indicates the
time when the fire detector operated and an output level of the sensor 1 at that time.
a memory 7 (hereafter referred to as ROM) which stores a predetermined basic level
as a basis to determine whether the output level of the sensor 1 should be taken as
fire. a memory 8 (hereafter referred to as RAM) which stores the time when the fire
detector operated and an output level of the sensor 1 at that time. These parts 1
through 8 are connected to a central processing unit 9 (hereafter referred to as CPU)
for their centralized control. Connected further to the CPU9 are an operating means
comprising a power supply E, switches SW1 ~ SW4 and resistors R1 ~ R4, input terminals IN1 ~ IN4 to which external apparatus corresponding to the individual switches SW1 ~ SW4 are connected, and output terminals OUT1 ~ OUT4 to which external apparatus corresponding to the indicating parts 5 and 6 are connected.
[0005] The switch SW
1, resistor R
2 and input terminal TN
1 are provided to clear the RAM8 by operation of the switch or external apparatus.
The switch SW
2, resistor R
z and input terminal IN
2, the switch SW
3, resistor R
3 and input terminal IN
3, and the switch SW
4, resistor R4 and input terminal IN
4 are provided to switch the indication of the first indicating part 5 from the time
to the output level of the sensor 1 by operation of the respective switch or external
apparatus, and to cause the second indicating part 6 to indicate the time when the
fire detector operated and the output level of the sensor 1 at that time. The output
terminals OUT
1 ~ OUT
4 are used for transmitting the time and output level signal to the external apparatus
corresponding to the first indicating part 5 and second indicating part 6.
[0006] Operation of the embodiment is described below with reference to the flow chart of
the CPU9 shown in Figure 2. The output of the sensor 1 is always amplified by the
amplifier 2, and the analogue signal indicating the output level is converted to a
digital signal by the A - D converter, which is then sent to the CFU9. A signal from
the clock part 4 indicating the present time, too, is sent to the CPU9. The ROM7 stores
the basic level for comparison with the output level of the sensor 1. As the CPU9
starts operating (step 1), the RAMS in which past data have been stored is cleared
(step 3) if the switch SW
1 for clearing the RAM8 is set in the ON position (step 2). In case the switch SW
1 is set in the OFF position (step 2), it is judged that there is no need of clearing
the RAM8, and with the signals from the clock part 4 and A - D converter 3 the present
time and output level of the sensor 1 are read in (stops 4 and 5) respectively. Then,
a discrimination is made as to whether the switch SW
2 used for indicating the output level of the sensor 1 on the first indicating part
5 is set in the ON position (step 6). Nevertheless, since the switch SW
2 is normally set in the OFF position, the first indicating part 5 indicates the present
time (step 7). And the output level of the sensor 1 which has been read in at the
above step 5 is compared with the basic level stored in the ROM7 (step 9). However,
as the output level of the sensor 1 does not reach the basic level before a fire breaks
out, a discrimination is made as to whether the second indicating part 6 is giving
the past indication (indication given at the time of the previous operation) (step
10). If yes, the second indicating part 6 is cleared (step 11). In the both cases
a discrimination is made as to whether the switches SW3 and SW
4 which cause the second indicating part 6 to indicate the operating time and the output
level of the sensor 1 at that time are set in the ON position (step 12). Nevertheless,
as the switches SW3 and SW
4 are normally set in the OFF position, the operation goes back to the above step 2
and repeatedly follows the above steps.
[0007] Now, if the output level exceeds the basic level (step 9), the fire detector produces
a fire alarm (step 13), which is transmitted to a control panel which is not shown
in the figure. And the time and the output level of the sensor 1 at this time is written
in and stored in the RAM8 (step 14), and the operations after the step 2 are repeated.
By switching on the switch SW
2 for output level indication (step 6) it is possible to cause the first indicating
part 5 to indicate the present output in place of the indicated time (step 8) so that
changes in output level of the sensor 1 may be checked whenever necessary.
[0008] If it is desirous to know the operating time of the fire detector and the output
level of the sensor 1 at that time later, the switches SW
3 and SW
4 should be set in the ON position (step 12). Then, the operating time stored in the
RAMS is read out (step 15) and indicated on the second indicating part 6 (step 16).
Furthermore the output level of the sensor 1 at the above operating time is read out
(step 17) and indicated on the second indicating part 6 together with the above operating
time (step 18).
[0009] The above has described the operating procedure by means of the switches SW
1 ~ SW
4. It is also possible to remotely cause the above operation to be performed by operating
external apparatus which constitute operating means and are connected to the input
terminals IN
1 ~ IN4. Furthermore it is possible to connect external apparatus which constitute
indicating means to the output terminals OUT
1 ~ OUT
4 so that the above mentioned various indications may be given on these indicating
means together with or in place of the indications given by the first and second indication
means. Although the first indicating part 5 is so devised that time alone is indicated
at all times and the output level can be indicated whenever necessary by operation
of the switch SW
2, other indicating methods may also be adopted, e.g. simultaneous indication of both
time and the output level, a choise of which should be made properly.
[0010] As can be seen from the above description the fire detector according to this invention
is equipped with a sensor which detects physical quantity of heat, light or smoke,
and means to store the time and output level of the sensor when the fire detector
operated and to indicate the stored time and output level at any time. Therefore it
is possible to confirm the time when the fire detector operated and the above mentioned
physical quantity at that time whenever necessity arises later. This feature is particularly
advantageous in case the fire detector falsely operated, and makes possible to clear
up the cause. As described above, this invention offers a fire detector having such
advantages that have never been realized in the conventional detectors.
Brief description of drawings
[0011] Figure 1 is a block diagram of an embodiment according to this invention. Figure
2 is a flow chart to illustrate operation of CPU9.
[0012]
