This invention relates to alarm latching technology associated with interconnected hazardous condition alarm units and improvements thereto.
Numerous systems have been developed that provide a network of alarm units for detecting a hazardous condition. Typically in these systems, the individual alarm units are interconnected to form the network to allow each alarm unit in the network to activate a respective horn when a hazardous condition is detected by any one of the alarm units.
In a network of multiple alarm units, it may be difficult to identify the location of the hazardous condition if a person cannot pinpoint which alarm unit triggered the system. As discussed below, several interconnected alarm systems have been developed that utilize a flashing light source (e.g., light emitting diode (LED)) on the triggering alarm unit to identify the alarm unit that detected the hazardous condition and triggered all of the interconnected alarm units within the network to activate their respective horns.
However, a person may not be able to recognize a flashing light source if the alarm unit is not in the line of sight of the viewer. For instance, a flashing light source can be easily missed by a person if the alarm unit is blocked by walls, ceiling fans, exit signs, or other obstructions. Likewise, a flashing light source may go unnoticed by a person with poor eyesight or if the person has his or her back turned to the alarm unit.
Moreover, in order to identify all of the alarm units that detected the hazardous condition (or to check the alarm units for false alarms), the person must go to every room having an alarm unit to determine whether the flashing light source has been activated. This task is magnified when there are a large number of alarm units in the network. Unless the alarm units are visible from a hallway, a person cannot merely walk down the hallway and look into every room to determine whether the alarm units are flashing a light source.
Another drawback of prior alarm systems is the lack of a quick and efficient means for resetting or clearing the light sources on the alarm units after the alarm unit that triggered the network of interconnected alarm units to activate their respective horns has been identified. Specifically, the light sources can only be reset by manually depressing a reset switch located on each individual alarm unit. The task is magnified when there are a large number of alarm units in the network. In large multi-story buildings having numerous alarm units, a substantial amount of time and effort is needed to reset all of the light sources in the network. A person is required to go to each and every room having an alarm unit therein, and manually reset each individual alarm unit having a flashing light source. Further, it is often difficult and time consuming to manually depress the reset switch on every alarm unit when the alarm units are positioned on or near the ceiling in an effort to detect rising smoke.
U.S. Pat. No. 4,349,812 to Healey is an example of a system having a plurality of alarm units. Each alarm unit is connected to a central control panel that includes a display board having a light source associated with each alarm unit. When an alarm unit detects a hazardous condition, the alarm unit sends a signal that latches an indicator circuit associated with the alarm unit, which in turn activates a light source on the display board for the alarm unit.
A person must physically go to the central control panel and visually check the display board to identify the alarm units that detected the hazardous condition. This may be difficult if the central control panel is not easily accessible (e.g., due to the hazardous condition) or if the person does not know where the central control panel is located within the building. Moreover, in an emergency situation where time is of the essence, it may be difficult to access the central control panel in a timely manner.
U.S. Pat. No. 6,353,395 to Duran provides an example of a network of interconnected alarm units, wherein each alarm unit has a light source that can be manually activated if the alarm unit has detected a hazardous condition. More specifically, a latch within the alarm unit that detected the hazardous condition and triggered all of the interconnected alarm units within the network to activate their horns (referred to herein as the “triggering alarm unit”) is set to a latched state when the triggering alarm unit detects a hazardous condition. Subsequently, if a test switch is actuated on the triggering alarm unit, a light source (i.e., pulsed illumination of an LED) is activated on the triggering alarm unit for a predetermined period (e.g., 10 minutes). The light source requires manual activation of the test switch on the triggering alarm unit to identify whether the alarm unit has detected the hazardous condition. Thus, a person must test each individual alarm unit in the network in order to identify all of the alarm units that triggered the network alarm. In a large building, a considerable amount of time and effort may be required before a single triggering alarm unit is located, even if the user chooses not to test every alarm unit in the building. In order to reset all of the latches in the network, the reset switch in each and every triggering alarm unit must be pressed. As such, the person must reset each individual alarm unit to ensure that all of the latches within the network are reset.
U.S. Pat. No. 7,075,444 to Tanguay discloses a network of alarm units connected by an interconnect line. When a hazardous condition is detected by the triggering alarm unit, a signal is sent through the interconnect line causing all of the alarm units in the network to sound their horns and/or flash their light sources. During the alarm condition (i.e., when the hazardous condition is being detected), an alarm origination test can be performed to identify the triggering alarm unit. Upon actuation of a test switch on any of the interconnected alarm units, the alarm origination test disables the horns and/or flashing light sources on all of the alarm units except for the alarm unit that is currently sensing the hazardous condition.
More specifically, the alarm origination test disables the interconnect line between the triggering alarm unit and the non-triggering remote alarm units. Thus, only the horn/light source on the alarm unit actually detecting the hazardous condition remains active. The horn/light source on the triggering alarm unit is only active when presently “sensing” the hazardous condition. As such, the triggering alarm unit can only be identified when the hazardous condition is present. It is advantageous to have the capability of latching a hazardous condition detection event into memory and subsequently testing the alarm units after the hazardous condition has been eliminated. The alarm units of Tanguay '444 do not include internal memory that latches upon detection of the hazardous condition, wherein the triggering alarm unit is identified based on the latched memory. Moreover, a means for resetting or clearing memory in the alarm units is not provided. Many of the features discussed above conform with established regulations and standards, e.g., Underwriters Laboratory Specification (UL) 217.
It is, therefore, an object of the present invention to provide a new, novel, alarm latching technology for interconnected hazardous condition alarm systems.
It is another object of the invention to address and overcome problems existing in prior art interconnected hazardous condition alarm systems.
Another object of the invention is to identify a signal origination alarm unit that triggered the audible alerts by employing on a resettable memory latch.
Still another object of the invention is to provide memory latches in the alarm units forming part of an interconnected alarm unit network, wherein the memory latches are set from an unlatched state to a latched state upon detection of a hazardous condition, thereby distinguishing a triggering alarm unit (latched state) from non-triggering alarm units (unlatched state).
Yet another object of the invention is to provide a test switch in each alarm unit, wherein actuation of the test switch in any of the individual alarm units disables the audible alerts in all of the networked alarm units not subject to alarm memory latch.
Still yet another object of the invention is to provide a reset switch in each alarm unit, wherein actuation of the reset switch in any of the individual alarm units resets the memory latches in all of the networked alarm units to unlatched states.
A final stated, but only one of additional numerous objects of the invention, is to provide a secondary alert different from the audible alert to differentiate an alarm origination test condition (secondary alert) from an emergency alarm condition (audible alert).
These and other objects are satisfied by a selective hazardous condition detector, comprising:
a) means for interconnecting said selective hazardous condition detector to a second selective hazardous condition detector;
b) means for detecting a select hazardous condition;
c) means for generating an alarm signal corresponding to a detected select hazardous condition;
d) memory means for recognizing said alarm signal;
e) latch means switchable between an unlatched state and a latched state, said latched state being established in response to said alarm signal and said latched state existing for a preset time period;
f) means for selectively actuating said memory means and switching said latch means to said latched state; and
g) actuatable reset means for resetting the state of said latch means;
h) whereupon actuating said latch reset means switches said latch means from the latched to the unlatched state after said preset time period while switching the latched means to said unlatched state immediately in said second selective hazardous condition detector.
The foregoing and other objects are satisfied by a system comprising at least a first and a second interconnected hazardous condition alarm units, each of said alarm units comprising:
The foregoing and other objects are further satisfied by a method comprising:
The foregoing and other objects and advantages will appear from the description to follow. In short, an embodiment of the invention provides alarm origination functionality that informs a person which alarm unit detected the hazardous condition (e.g., smoke and/or carbon monoxide (CO)) and triggered the system to sound. An audible indication is efficacious for identifying the triggering alarm unit. The concept, in at least one embodiment of the invention, involves automatically latching the triggering alarm unit from an interconnected, hazardous condition network to activate an audible alert only on the triggering alarm unit for a predetermined period (e.g., 60 seconds; the predetermined period may be more or less based on the desired preference of the manufacturer or person). In at least one embodiment, the alarm units do not rely on and do not include a flashing light source.
In at least one embodiment of the invention, an alarm origination test is performed by pressing and releasing the test switch. Once released, except for the triggering alarm unit, all of the interconnected alarm units within the network cease to provide any audible and visual alerts. The only alarm unit that emits an audible alert is the triggering alarm unit. The audible alert persists for a specified limited duration, e.g., 60 seconds. If desired, the alarm unit can also have a flashing light source for coordinated visual indication.
For definitional purposes and as applicable, “connected” includes physical, whether direct or indirect, and/or functional, as for example, a plurality of hazardous condition alarm units connected to an interconnect line. Thus, unless specified, “connected” is intended to embrace any operationally functional connection, e.g., wireless.
In the following description, reference is made to the accompanying drawings, and which is shown by way of illustration to the specific embodiments in which the invention may be practiced. The following illustrated embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It is to be understood that other embodiments may be utilized and that structural changes based on presently known structural and/or functional equivalents may be made without departing from the scope of the invention.
Given the following detailed description, it should become apparent to the person having ordinary skill in the art that the invention herein provides a network of interconnected alarm units, wherein a triggering alarm unit switches an internal actuatable latch from an unlatched state to a latched state when a hazardous condition is detected. The triggering alarm unit sends a signal to all of the interconnected alarm units to active their respective horns. The triggering alarm unit can be identified by disabling the horns on all of the alarm units that do not have an actuatable latch in the latched state (i.e., all of the non-triggering alarm units). Thus, only the horn on the triggering alarm unit remains active. The actuatable latches can be reset to an unlatched state by pressing a reset switch in any of the individual alarm units.
The novel features which are believed to be characteristic of the present invention, as to its structure, organization, use and method of operation, together with further objectives and advantages thereof, will be better understood from the following discussion.
In response to the detection of the select hazardous condition, the method switches an actuatable latch in the triggering alarm unit from an unlatched state to a latched state (220) and generates an audible alert in all of the interconnected hazardous condition alarm units (230). Examples of audible alerts include horns, bells, and/or buzzers. Different types of audible alerts may be generated to differentiate between the detection of smoke and the detection of CO. Alternatively, when allowed by regulation and/or standard, different patterns and/or different frequencies of the same type of audible alert may be utilized to differentiate between the detection of smoke (e.g., low frequency horn) and the detection of CO (e.g., high frequency horn).
In at least one embodiment, the audible alert is generated in the alarm units by sending an alert signal from the triggering alarm unit through the interconnect line to the connected alarm units. In response to receiving the alert signal, the audible alert is activated in all of the hazardous condition alarm units. The audible alert is maintained in the triggering alarm unit even after the select hazardous condition has been eliminated. The audible alert is disabled in the non-triggering alarm units after the select hazardous condition has been eliminated.
During an alarm origination test, a switch providing a test functionality (test switch) is actuated in order to identify the triggering alarm unit (240). Actuation of the test switch disables the audible alert in each interconnected hazardous condition alarm unit having an actuatable latch in the unlatched state (i.e., the non-triggering alarm units). Actuation of the test switch does not affect the audible alert in the alarm unit having an actuatable latch in the latched state (i.e., the triggering alarm unit). Thus, because the triggering alarm unit switches its actuatable latch to the latched state after detecting the hazardous condition, the audible alert in the triggering alarm unit is not disabled by actuation of the test switch (which only disables alarm units having actuatable latches in the unlatched state). The audible alerts in the non-triggering alarm units are disabled for a predetermined period of time (e.g., 10 minutes). However, as required by applicable standards, e.g., UL 217, the alarm origination test does not prevent a non-triggering alarm unit from generating an audible alert and switching its actuatable latch to the latched state if that alarm unit detects a hazardous condition during the alarm origination test.
A switch providing a reset functionality (reset switch) is actuated in only one of the interconnected alarm units to reset the actuatable latch in each and every alarm unit in the network to the unlatched state (250). Thus, a person is not required to reset each alarm unit individually; resetting any one of the interconnected alarm units resets the actuatable latches in all of the interconnected alarm units. As described below, a single switch or button could function as both the test switch and the reset switch, depending on, for example, how long the switch is depressed.
In another embodiment, a visual alert is generated in the hazardous condition alarm units. For example, a strobe light and/or flashing LED is activated on all of the interconnected alarm units simultaneously with the generation of the audible alert. The visual alert is disabled in each alarm unit having an actuatable latch in the unlatched state (i.e., the non-triggering alarm units) by actuation of the test switch. The test switch does not affect the visual alert in the alarm unit having an actuatable latch in the latched state (i.e., the triggering alarm unit).
In yet another embodiment, the method generates a secondary alert different from the audible alert in all of the interconnected hazardous condition alarm units. The secondary alert is disabled in each alarm unit having an actuatable latch in the unlatched state (non-triggering alarm units). For example, upon detecting a hazardous condition, the interconnected alarm units of the network sound a horn in a specific audible pattern (audible alert). During the alarm origination test, all of the interconnected alarm units sound the horn in a different pattern or generate a discrete digitized sound, such as a bell (secondary alert), wherein the secondary alert in the non-triggering alarm units are subsequently disabled. The secondary alert is utilized to distinguish an alarm origination test (secondary alert) from an emergency alarm condition (audible alert).
An embodiment of the invention provides a system 200 having a network of interconnected hazardous condition alarm units 210, 220, 230, 240, and 250 connected by an interconnect line 260. For example, a preferred embodiment of the system 200 is illustrated in
In at least one embodiment of the invention, represented by the diagram illustrated in
Consistent with the requirements of UL 217, the internal oscillator and timing circuitry keep standby power to a minimum by powering down the IC (e.g., for 1.66 seconds) and sensing for a hazardous condition (e.g., for only 10 ms). A check is made (e.g., every 24 on-off cycles) for a low battery condition. By substituting other types of sensors or a switch for the ionization detector, this very-low-power IC can be used in numerous other battery-operated safety/security applications.
Terminal 1 (also referred to herein as the “TIMER START pin” or “pin 1”) provides an input to start the reduced sensitivity timer mode. Moreover, terminal 7 (also referred to herein as the “TIMING RES pin” or “pin 7”) provides a terminal for the timing resistor and sets the internal bias to affect timing. The TIMER OUT pin is also referred to herein as the “terminal 4” or “pin 4” and is used with a resistor to adjust sensitivity during the timer mode. As illustrated in
Terminal 2 (also referred to herein as the “I/O pin” or “pin 2”) provides an input/output (I/O) terminal to the interconnected alarm units. As illustrated in
As described above, when multiple alarm units are interconnected through the I/O line, the actuatable latch allows a person to identify which alarm unit or alarm units initiated an audible alert. When a local alarm condition occurs, the triggering alarm unit sounds its horn and latches the event in memory. The networked, non-triggering alarm units also sound their horns, but do not latch the event in memory. An alarm unit does not latch an alarm condition if it was the result of a push-to-test event. After the alarm condition clears and all alarm units have stopped sounding their horns, a person identifies the initiating devices by depressing the test switch on any of the interconnected alarm units, which makes the I/O pin go high immediately and all interconnected alarm units begin to sound their horns. When the person releases the test switch (e.g., within 10 seconds), all of the horns turn off, except for the horn on the triggering alarm unit, which continues to sound its horn (e.g., for 60 more seconds).
The light source of a triggering alarm unit with an actuatable latch in the latched state behaves the same as an alarm unit with an actuatable latch in the unlatched state. A person resets all of the actuatable latches to the unlatched state in the network of interconnected alarm units by depressing the reset switch on any of the interconnected alarm units (e.g., for 10 seconds).
Terminal 3 (also referred to herein as the “LOW-V SET pin” or “pin 3”) is used with a resistor to adjust the low battery threshold. As illustrated in
Terminal 5 (also referred to herein as the “LED pin” or “pin 5”) provides an output to drive the flashing light source. As illustrated in
Terminal 6 (also referred to herein as the “VDD pin” or “pin 6”) provides a positive supply voltage; Terminal 9 (also referred to herein as the “VSS pin” or “pin 9”) provides a negative supply voltage. As illustrated in
Terminal 8 (also referred to herein as the “FEEDBACK pin” or “pin 8”) provides an input for driving a piezoelectric horn. As illustrated in
Terminal 10 (also referred to herein as the “HORN1 pin” or “pin 10”) provides an output for driving the piezoelectric horn; terminal 11 (also referred to herein as the “HORN2 pin” or “pin 11”) provides a complementary output for driving the piezoelectric horn. As illustrated in
Terminal 13 (also referred to herein as the “SENSITIVITY SET pin” or “pin 13”) is used with a resistor to adjust the sensitivity for a specific chamber. Terminal 15 (also referred to herein as the “DETECT IN pin” or “pin 15”) provides an input from the detector chamber. As illustrated in
An active guard is provided on GUARD1 and GUARD2, the two pins adjacent to the detector input, and the DETECT IN pin. Terminal 14 (also referred to herein as the “GUARD1 pin” or “pin 14”) provides an active guard1 for the detector input; and, terminal 16 (also referred to herein as the “GUARD2 pin” or “pin 16”) provides an active guard2 for the detector input. As illustrated in
Referring to
In another embodiment of the invention, the alarm units include low power CMOS ionization type smoke detector ICs. With few external components, this IC provides all of the features of an ionization type smoke detector. An internal oscillator strobe powers the hazardous condition detection circuitry (e.g., for 10.5 mS every 1.66 seconds) to keep the standby current to a minimum. A check for a low battery condition is performed (e.g., every 40 seconds) when in standby. A charge dump feature quickly discharges the interconnect line when exiting a local alarm condition. Utilizing low power CMOS technology, the IC is used in hazardous condition detectors that comply with Underwriters Laboratory Specification UL 217, UL 268, and/or UL 2034.
If the unit is in local alarm (i.e., sounding its horn), then the transition of pin 1b from a high to low level resets the unit out of local alarm, activates the I/O charge dump feature, and initiates a timer. During this timer period (e.g., 12 minutes), the open drain NMOS on pin 4b is strobed on coincident with the internal clock. A resistor connected to this pin and pin 13b is used to modify the detector sensitivity during the timer period. During the timer period, the light source flashes (e.g., for 10.5 mS every 10 seconds). If the smoke level exceeds the reduced sensitivity set point during the timer period, the alarm unit goes into a local alarm condition (i.e., the horn sounds) and the timer mode is not cancelled. If an external only audible alert occurs during the timer mode, the timer mode is not cancelled. If the test switch is pushed in a standby, reduced sensitivity mode, the alarm unit is tested normally. Upon release of the test switch, the timer mode counter is reset and restarted. Once the timer is activated, it is reset by loss of power to the IC or after the timer times out.
The smoke comparator compares the ionization chamber voltage to a voltage derived from a resistor divider across VDD. This divider voltage is available externally on pin 13b. When a hazardous condition is detected, this voltage is internally increased (e.g., by 230 mV nominal) to provide hysteresis and make the detector less sensitive to false triggering. Pin 13b is used to modify the internal set point for the hazardous condition comparator by use of external resistors to VDD or VSS. Nominal values for the internal resistor divider are indicated in
The guard amplifier and outputs are active and are within, for example, 50 mV of the DETECT input (pin 15b) to reduce surface leakage. The guard outputs (pins 14b and 16b) also allow for measurement of the DETECT input without loading the ionization chamber.
Pin 2b provides the capability to common many alarm units in a single interconnected network. If a single alarm unit detects a hazardous condition, the pin 2b is driven high. This high signal causes the interconnected alarm units to activate their respective horns. The light source flashes (e.g., LED pulsed every 1 second for 10.5 mS) on the triggering alarm unit and is inhibited on the alarm units that are in alarm due to the I/O signal (i.e., the non-triggering alarm units). An internal sink device on the pin 2b helps to discharge the interconnect line. This charge dump device is active for 1 clock cycle after the unit exits the alarm condition (e.g., 1.67 seconds). The interconnect input has a digital filter (e.g., 500 mS nominal). This allows for interconnection to other types of alarm units (e.g., CO) that may have a pulsed interconnect signal.
Pin 3b selects the NFPA72 horn tone (high) or the ⅔ duty cycle continuous tone (low). If pin 3b is externally connected high, a current limiting resistor (e.g., of at least 1.5 K) from pin 3b to VDD is used. The IC internally limits the current from VSS to VDD in the event of accidental polarity reversal. If an input is connected to VDD, the connection is made through a resistance (e.g., of at least 1.5 K) to limit the reverse current through this path. Pin 6b is the VDD pin; and, pin 9b is the VSS pin.
In the low battery detection mode, an internal reference is compared to the voltage divided VDD supply. The battery is checked under load via the light source low side driver output since low battery status is latched at the end of the light source pulse (e.g., 10.5 mS). For example, an LED is pulsed on for 10.5 mS every 40 seconds in standby; in alarm mode, the LED is pulsed on for 10.5 mS every 1 second. Pin 5b is the LED pin.
Pin 7b is the ROSC pin; and, pin 12b is the COSC pin. For example, the period of the oscillator is nominally 1.67 seconds in standby, wherein every 1.66 seconds, the detection circuitry is powered up for 10.5 mS and the status of the smoke comparator is latched. The LED driver is turned on (e.g., for 10.5 mS) and the status of the low battery comparator is latched (e.g., every 40 seconds). The smoke comparator status is not checked during the low battery test, during the low battery horn warning chirp, or when the horn is on due to a detected hazardous condition. If a hazardous condition is detected, the oscillator period increases (e.g., to 20.5 mS). The oscillator period is mainly determined by the values of R1, R2, and C3. For example, the oscillator period T=TR+TF, where TR=0.69×R1×C3 in standby and TR=0.69×(R1/R2)×C3 in alarm, TF=0.69×R2×3.
At power up, all internal registers are reset. The low battery set point is tested at power up by holding FEED low and COSC high at power up. Pin 8b is the FEED pin. HB changes state as VDD passes through the low battery set point. Pin 10b is the HB pin; and, pin 11b is the HS pin. By holding pin 12b high the internal power strobe is active. Functional testing is accelerated by driving pin 12b (e.g., with a 4000 HZ square wave); however, the strobe period (e.g., 10.5 mS) is maintained for proper operation of the analog circuitry.
In at least one embodiment of the invention, each hazardous condition alarm unit includes at least one hazardous condition detector 910, a horn 920, a signal communication member 930, an actuatable latch 940, a test switch 950, and a reset switch 960. A preferred embodiment of the alarm unit 210 is illustrated in
The horn 920 generates an audible alert in response to detection of a select hazardous condition by the alarm unit 210, 220, 230, 240, and/or 250. The audible alert conforms to mandated patterns established by regulation or standard, e.g., UL 217. Moreover, the audible alert remains active in the alarm units having the actuatable latch in the latched state (i.e., the triggering alarm unit) after the select hazardous condition has been eliminated.
The signal communication member 930 communicates a signal between the alarm units 210, 220, 230, 240, and 250. The signal is sent through an interconnect line in response to detection of the select hazardous condition. The signal causes activation of the respective horns in the alarm units 210, 220, 230, 240, and 250. The actuatable latch 940 is switchable between an unlatched state and a latched state. The latched state is established in response to the detection of the select hazardous condition by the triggering alarm unit.
The test switch 950 is switchable between a first position and a second position. The second position of the test switch 950 disables the horn in each alarm unit 210, 220, 230, 240, and 250 having an actuatable latch in the unlatched state (i.e., the non-triggering alarm units). As such, if an alarm unit did not detect a select hazardous condition, and therefore did not switch its respective actuatable latch to a latched state, then the test switch 950 would disable the horn of that alarm unit. Each alarm unit 210, 220, 230, 240, and 250 having an actuatable latch in the latched state (the triggering alarm units) is unaffected by the test switch for a predetermined period of time following actuation of the test switch (e.g., 60 seconds). In other words, the alarm unit that detected the select hazardous condition continues to sound an audible alert, while the alarm units that did not detect the select hazardous conditions are silenced. During this test period, a person can audibly locate the triggering alarm unit although vision may be impaired by walls and/or other visual obstructions. As contemplated herein, actuation of the test switch 950 does not affect the sensitivity in the non-triggering alarm units. Thus, although the horns are disabled in the non-triggering alarm units by actuation of the test switch 950, the sensitivity of the hazardous condition detectors remains the same throughout the alarm origination test.
The reset switch 960 resets the actuatable latch in every alarm unit 210, 220, 230, 240, and 250 to the unlatched state. As described above, actuating a reset switch in any of the alarm units 210, 220, 230, 240, and 250 resets the actuatable latches in all of the alarm units 210, 220, 230, 240, and 250. Although
In another embodiment, the alarm units 210, 220, 230, 240, and 250 each have a visual alert. For instance, the alarm unit 210 has a visual alert 970. The visual alerts are generated in the alarm units 210, 220, 230, 240, and 250 in response to a select hazardous condition detected by any of the alarm units 210, 220, 230, 240, and 250. During an alarm origination test, actuation of any of the test switches in the alarm units 210, 220, 230, 240, and 250 disables the visual alert of each alarm unit 210, 220, 230, 240, and 250 having an actuatable latch in the unlatched state (i.e., the non-triggering alarm units).
In yet another embodiment, actuation of a test switch in any of the alarm units 210, 220, 230, 240, and 250 activates a secondary alert in all of the alarm units 210, 220, 230, 240, and 250. The secondary alert (e.g., bell) is different from the audible alert (e.g., buzzer) to differentiate an alarm origination test (secondary alert) from a hazardous alarm condition (audible alert). Subsequent release of the test switch disables the secondary alert in each alarm unit 210, 220, 230, 240, and 250 having an actuatable latch in the unlatched state (i.e., the non-triggering alarm units).
Other modifications and alterations may be used in the implementation and use of the latching concept of the present invention without departing from the spirit and scope thereof.
While described herein as a hardwire system, the invention is equally employable in an array of interconnected wireless units where the interconnect is provided through appropriate and known RF communication protocol.
This application claims the benefit of U.S. provisional application Ser. No. 60/989,369, filed on Nov. 20, 2007, which is incorporated herein by reference.
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Number | Date | Country | |
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20090128353 A1 | May 2009 | US |
Number | Date | Country | |
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60989369 | Nov 2007 | US |