Abstract:
A system and method for waking a person includes the provision of tactile stimulation in a repeating interrupted pattern upon the detection of an alarm signal indicative of an event for which the person should be awakened. In one embodiment, a device for waking a person comprises a circuit for generating a driver signal in response to an alarm signal, the driver signal having a repeating interrupted pattern; an electrically controlled switching device having a control input, a power input and a power output, the power input being connectable to a power source, the control input being connected to receive the driver signal from the circuit; and a tactile stimulation device connected to the power output of the electrically controlled switching device, the tactile stimulation device being configured to produce a tactile stimulation.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application Ser. No. 60/632,535, filed Dec. 3, 2004, the entire contents of which are incorporated herein by reference. 

   BACKGROUND 
   During a fire, the occupants of a building may only have a few minutes to escape without harm. Due to the potentially small escape time, it is imperative to give ample warning to the occupants of a burning building. Most devices sold by the fire safety industry rely on audible alarms to alert the occupants in a residential building. Unfortunately, these devices do not help the hearing impaired. Thus, a need arises for a device that provides ample protection for the hearing-impaired in case of a fire emergency. 
   When it comes to meeting the general public&#39;s need for adequate fire emergency notification devices, one is forced to consider whether the standard off-the-shelf audible smoke detector provides the most appropriate stimulus to prompt a person to begin the egress process. It is estimated that 17% of Americans over the age of 18 have some form of hearing loss (35 million people), and over 3% of those people are severely hearing impaired or profoundly deaf [Lucas, 2004]. Hence, a large number of Americans are at a disadvantage for receiving notification of a fire in their residence by the standard audible smoke detector, and the number of people around the world at this disadvantage is even larger. 
   Waking persons from sleep is of significant importance because the majority of fire deaths in residential settings occur between the sleeping hours of 11:00 pm and 6:00 am. Although only 20% of fires are reported to have taken place during this temporal window, nearly 50% of fire fatalities occur during this time [Ahrens, 2003]. 
   Recent legislation, such as the Americans with Disabilities Act (ADA), has recognized the disadvantage that deaf and hard-of-hearing people have concerning notification by audible fire alarms. As a result, many automatic fire detection systems are now required to signify with an audible alert accompanied by a strobe to provide a visual indication of fire alarm activation. 
   Known in the art are devices that use visual signals to alert the hearing-impaired of a fire emergency. Examples of such devices are described in U.S. Pat. Nos. 4,227,191 and 4,287,509. These devices combine a detector and a visual alarm in a single device. Another visual warning device is disclosed in U.S. Pat. No. 5,012,223. This device detects the sound from a remote smoke detector and activates a light in response thereto. Visual alarm devices such as these suffer from the serious drawback of being largely ineffective in alerting a hearing-impaired individual who is asleep. 
   Systems combining tactile stimulation (e.g., vibrators and bed shakers) have been proposed to address this need. One such device is described in U.S. Pat. No. 4,380,759. This device includes a vibration sensor that is placed next to a smoke detector. When the smoke detector activates, the vibration from the audible alarm triggers a vibrating reed that causes a mild sensation on the skin. Devices such as this are cumbersome to use (especially when the device will only be used at a location temporarily, as in a hotel room) as the user must place the transmitting unit in physical contact with the smoke detector, which is often on a ceiling or otherwise difficult to reach. Other devices for the hearing impaired (e.g., the device disclosed in U.S. Pat. No. 5,917,420) involve the transmission of signals from a detector to a furniture shaker or other tactile stimulation device. Devices such as these are usually quite expensive and require special hardware. U.S. Pat. No. 5,651,070 describes a warning device that “listens” for sounds made by devices such as doorbells and smoke detectors and activates a tactile stimulation device in the form of a wrist-watch. This device records a desired audio alarm and continually compares the recorded alarm to ambient sounds picked up from a microphone. This device is burdensome to use in that it requires the user to record the desired sound prior to use. This can be a problem, for example, when a person enters a hotel room late at night because activation of the smoke detector alarm for the purpose of making the recording may disturb other guests. 
   To address the above-discussed problems with devices such as these, the assignee of the present application has proposed a system described in co-pending U.S. patent application Ser. No. 10/676,779, filed Oct. 2, 2003 and entitled “Method and Apparatus of for Indicating Activation of a Smoke Detector Alarm,” the contents of which are hereby incorporated by reference herein. This system detects a temporal pattern associated with an audible smoke alarm and, upon detection, activates a tactile device such as a bed shaker to wake a person. 
   While this system has proven very effective, testing of the system with a standard, constantly vibrating bed shaker as the tactile device has revealed that the system was effective in only 76% of the hard of hearing subjects and in only approximately 92% of the deaf subjects. In contrast, hearing able subjects awoke to the bed shaker with constant vibration close to 95% of the time. The lack of response of the hard of hearing and deaf subjects may be due to their conditioned response to the bed shaker as a non-emergency alarm. 
   The standard audible smoke detector, the emergency alerting system recommended by the fire community, was proven to be effective in awakening 58% of the hard of hearing population and 0% of the deaf subjects. The weighted average effectiveness per hearing level for the U.S. population was found to be 84%. The visual alerting device which is the recommendation by the fire safety community for the hearing impaired population was found to be effective only 35% of the time for the hearing impaired and 60% for the deaf subjects. The visual alerting device had an effective awakening of less than 35% for the hearing able population and a weighted average effectiveness across all hearing levels of 35%. Although the results reported above are over a small statistical sample, they are nonetheless believed to be representative of the results that would be obtained over a larger sample. 
   The standard audible smoke detector, which is installed in most homes throughout the United States, was found to be only 84% effective across all hearing populations when weighted across the US population on the basis of hearing ability. This means that of the 204 million Americans over 18, thirty-two million might not awaken to the standard audible detector. Many smoke detector manufacturers have already come to accept this reality and now include a statement in their mounting instructions pertaining to the fact that a properly powered activated audible alarm may not be able to awaken a sleeper even when installed to meet the 85 dB at 10 feet or 15 db above ambient NFPA 72 requirements. 
   A low frequency audible horn, 400–500 Hz and approximately 85 dB, was tested with thirty-six persons of varying hearing ability. Of the five subjects with no hearing loss, all were awakened by the low frequency audible horn. Of the partially hearing subjects, 92% were awakening by the low frequency horn, 35% more frequently than with the standard audible horn. Of the fully deaf subjects, 11% awoke to the low frequency horn. The low frequency horn effectively awakened a larger percentage of subjects, regardless of hearing ability, than the standard audible horn. 
   What is needed is a more effective method of waking deaf and hard of hearing subjects. 
   SUMMARY 
   The aforementioned issues are met to a great extent by a system including a tactile stimulation device that provides non-constant tactile stimulation in order to awaken a person. Preferably, the tactile stimulation provided by the tactile stimulation device follows the same temporal pattern as the audible alarm in smoke/fire detectors manufactured after 1996, which is set forth in National Fire Protection Association standard NFPA 72. The tactile stimulation device is a bed shaker in preferred embodiments. 
   The tactile stimulation device may be used to wake a person for any reason. In one embodiment, the tactile stimulation device may be connected to a smoke/fire detector or a carbon monoxide detector. In another embodiment, the tactile stimulation device is connected to a device described in the above-referenced commonly owned co-pending U.S. patent application that detects an audible alarm from a smoke detector. In yet another embodiment, the tactile stimulation device may be connected to an alarm clock to wake a person at a desired time. In still another embodiment, the tactile stimulation device may be connected to a door bell or a telephone. 
   The tactile device may be coupled with a light (preferably an LED) which decreases and increases in intensity with the same T-3 pattern as the vibratory portion of the device. Although the light dims during periods corresponding to the “off” portions of the T3 pattern, the light maintains sufficient light intensity to allow for the recognition of an egress path from the room in which the device was placed. In another embodiment, two lights are provided. The first light activates in a T-3 pattern at the time at which the tactile device is active, and the second light maintains a steady intensity to aid in the egress process. 
   The tactile device may also be coupled with a device that produces a low frequency sound. The low frequency sound has been shown to effectively waken those with hearing loss in the higher frequencies. The low frequency sound preferably has a frequency below 1500 Hz, more preferably in the range of 300 Hz–600 Hz, and most preferably in the range of approximately 400–500 Hz and replicates the T-3 pattern of the tactile device. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the invention and many of the attendant features and advantages thereof will be readily obtained as the same become better understood by reference to the following detailed description when considered in connection with the accompanying drawings of preferred embodiments, wherein: 
       FIG. 1  is a timing diagram showing the audible alarm pattern for smoke detectors set forth in National Fire Protection Association standard NFPA 72. 
       FIG. 2  is a block diagram of a system for waking a person according to one embodiment of the present invention. 
       FIG. 3  is a circuit diagram of a portion of the tactile stimulation device of  FIG. 2 . 
       FIG. 4  is a block diagram of a system for waking a person according to another embodiment of the invention. 
       FIG. 5  is a flowchart showing the operation of a microcontroller that forms part of the system of  FIG. 4 . 
       FIG. 6  is a perspective view showing an exemplary housing for a portion of the circuit of the system of  FIG. 4 . 
       FIG. 7  is a perspective view showing an exemplary housing for a bed shaker according to an embodiment of the invention. 
   

   DETAILED DESCRIPTION 
   The present invention will be discussed with reference to preferred embodiments of tactile stimulation devices. Specific details are set forth in order to provide a thorough understanding of the present invention. The preferred embodiments discussed herein should not be understood to limit the invention. Furthermore, for ease of understanding, certain method steps are delineated as separate steps; however, these steps should not be construed as necessarily distinct nor order dependent in their performance. 
   As discussed above, the inventors have discovered that a constantly vibrating tactile stimulation device is less than optimal for waking persons, particularly hearing impaired or deaf persons, from sleep. As a result, it has been determined that use of a tactile stimulation device in a non-continuous manner is better suited for waking persons from sleep. The National Fire Protection Association standard NFPA 72 mandates that smoke detectors emit audible alarm signals with a repeating temporal pattern shown in  FIG. 1  ( FIG. 1  illustrates two repetitions of the repeating temporal pattern). This pattern, also referred to herein as a T-3 pattern, may be described as consisting of three short “on” periods, each of which is separated by a short “off” period, followed by a longer “off” period. The length of the short on and off periods is specified as 0.5 seconds “on”+/−10% followed by 0.5 seconds “off” +/−10%. The long “off” period is specified as 1.5 seconds +/−10%. Alternatively, the above-described T3 pattern may be described as consisting of an uneven number of “on” and “off” periods of equal half-second (+/−10%) duration; i.e., a first “on” period, a first “off” period, a second “on” period, a second “off” period, a third “on” period, and three consecutive “off” periods. 
   In response to the lack of effectiveness of the audible smoke detector and relative positive response to the bed shaker, a new device was introduced into test series. In this device, a bed shaker vibrates in accordance with the T-3 pattern. That is, the bed shaker vibrates during the portions of the T-3 pattern that are “high” or “on” and does not vibrate during the portions of the T-3 pattern that are “low” or “off.” The tactile device was tested on 60 subjects of various hearing levels. Every subject regardless of hearing level awoke to the device. 
   A block diagram of the T-3 pattern bed shaker system is illustrated in  FIG. 2 . An alarm signal from a smoke detector (not shown in  FIG. 2 ) or other device is input to a T-3 circuit  110 . When the alarm signal is present, the T-3 circuit outputs a signal matching the T-3 temporal pattern illustrated in  FIG. 1 . This output signal from the T3 circuit controls a power field effect transistor (FET)  120  (or other switching device, such as a relay) such that power is applied to a bed shaker  130  when the output signal from the T-3 circuit  110  is “high.” In this manner, the bed shaker  130  vibrates when the T-3 temporal pattern is “high” and does not vibrate when the T-3 temporal pattern is low. 
   A detailed circuit diagram of a preferred embodiment of the system of  FIG. 2  is illustrated in  FIG. 3 . A bed shaker  230  is connected between the positive terminal of a power supply  240  and the drain of a power FET  220 . The source of the power FET  220  is connected to the negative terminal of the power supply  240 . With this arrangement, a circuit is formed through the power FET  220  such that power is supplied to the bed shaker  230  when a sufficiently positive signal is applied to the gate of the power FET  220 . 
   The gate of the power FET  220  is controlled by the “brass” output (pin  10 ) of a Motorola/Freescale MC145018 ionization smoke detector integrated circuit, which is typically used to drive a horn. This MC145018 IC 211 is described in data sheet MC145018/D (available at www.freescale.com/files/sensors/doc/data_sheetMC145018.pdf), the contents of which are hereby incorporated by reference herein. Normally, the horn driver output signal on pin  10  is a high frequency square wave during the “on” portions of the T-3 pattern. However, by feeding back the “silver” output on pin  11  and the output signal itself from pin  10  (via R 3 ) to the feedback input on pin  8 , the output signal on pin  10  is held to a constant “on” state during the “on” portions of the T3 pattern. 
   In the circuit  210  of  FIG. 3 , an activation input  250  from a smoke detector or other device is connected to pin  2 , which is the “I/O” pin of the MC145018 IC 211. This pin is normally used to interconnect several units so that a smoke detection in one unit will trigger an alarm in all units. Of course, it is also possible to use the MC145018 IC 211 itself for the smoke detection function. The remaining connections to the MC145018 IC 211 shown in  FIG. 3  are straightforward. Power to the IC is supplied at pin  6  from power source  260 , and the IC 211 is grounded at pin  9 . A timing resistor R 2  (8.2 MΩrecommended) and a timing capacitor C 1  (0.1 μF recommended) are connected to pin  7 . Finally, pin  12  is connected to a capacitor C 2  (also 0.1 μF recommended). 
   As discussed above, the activation input signal  250  is preferably generated by a smoke/fire detector. However, the invention is not so limited and the other devices such as carbon monoxide detectors, alarm clocks, doorbells, telephones, etc., may also be used as the source of the activation input signal  250 . The invention may also be used with the device disclosed in the above-referenced commonly owned U.S. patent application, which detects the audible alarm from a smoke detector. 
   A block diagram of another embodiment  400  is illustrated in  FIG. 4 . This embodiment is controlled by a microcontroller  410 . The microcontroller  410  receives an alarm signal input from a device such as a smoke detector, a circuit for detecting an audible alarm from a smoke/fire detector such as that disclosed in the above-referenced commonly owned U.S. patent application, a doorbell, a telephone, or any other device (not shown in  FIG. 4 ). The alarm signal is preferably continuously asserted while the alarm condition exists. In other words, in the case of a smoke/fire detector, the alarm signal is continuously asserted while smoke or fire is detected rather than only being asserted when an audible alarm signal is generated. In the case of a telephone, the alarm signal is continuously asserted while the phone is ringing, including the periods between the rings. In the case of a doorbell, the alarm signal is continuously asserted while the doorbell is ringing. 
   The microcontroller  410  is connected to control a relay  420 , which is connected between a power source  430  and a tactile stimulation device  440 . This allows microcontroller  410  to turn the tactile stimulation device  440  on and off. Electrically controlled switching devices (e.g., transistors) other than the relay  420  may be used in other embodiments. A first light emitting diode (“LED”)  450  and a second light emitting diode  460  are also connected to the microcontroller  410 . The first LED  450  is constantly lit while the alarm signal is asserted in order to provide light for egress from a room or to assist a user in taking other action (e.g., answering a telephone, locating a light switch, etc.). Those of skill will recognize that other types of lights could be used in place of the LEDs and that, depending upon the power requirements for the lights, connection via a relay, power transistor or other electrically controlled switching device may be necessary. The second LED  460  is strobed (either on and off or from a bright condition to a dim condition) while the alarm signal is asserted. Preferably, the second LED  460  is strobed in the same T3 pattern in which the tactile stimulation device  440  is activated. A low frequency audible horn  470 , preferably approximately 500 Hz, is also connected to the microcontroller  410 . The low frequency horn  470  is also preferably activated in the same T3 pattern in which the tactile stimulation device  440  is activated. 
   Operation of the embodiment  400  will be described with reference to the flowchart  500  of  FIG. 5 . The microcontroller  410  determines whether an alarm signal is detected at step  510 . If no alarm signal is present, the microcontroller repeats step  510  until an alarm signal is detected. When an alarm signal is detected, the microcontroller  410  turns the first LED  450  on at step  520 . Next, the microcontroller  410  activates the second LED  460 , the low frequency horn  470 , and the tactile stimulation device  440  (by controlling the relay  420 ) in a non-continuous, or interrupted, pattern at step  530 . Preferably, the interrupted pattern is the T3 pattern discussed herein. The microcontroller  410  then determines whether the alarm signal is still being asserted at step  540 . If the alarm signal is being asserted, the microcontroller  410  jumps to step  530  to continue activation of the second LED  460 , the low frequency horn  470 , and tactile stimulation device  440  in the non-continuous pattern. If the alarm signal is no longer being asserted, the microcontroller  410  turns the first LED  450  off at step  550  and jumps to step  510 . 
   In the above-mentioned embodiment, the second LED  460  and the tactile stimulation device  440  are always activated for at least one complete period of the non-continuous pattern even if the alarm signal terminates prior to the completion of the non-continuous pattern period. However, in other embodiments, the microcontroller  410  may be programmed to terminate the activation of the second LED  460  and the tactile stimulation device  440  as soon as the alarm signal is no longer asserted. Also, in yet other embodiments of the invention, the microcontroller  410  may be programmed to activate the first and second LEDs  450 ,  460 , the horn  470  and the tactile stimulation device  440  for a predetermined period of time or until a user deactivates the device. 
   As discussed above, an alternative to the two-LED embodiment illustrated in  FIGS. 4 and 5  is an embodiment with a single LED. In such an embodiment, the single LED is made bright when the tactile stimulation device is active and made dim (but still bright enough to provide light in order to facilitate egress from the room or other action) when the tactile stimulation device is inactive (e.g., during the “off” periods of the T3 or other non-continuous pattern). 
     FIGS. 6 and 7  are perspective views of housings  600 ,  770  in which the embodiment described in  FIG. 4  may be enclosed. The housing  600  is preferably sized to be placed on a tabletop  610  such as a nightstand. The microcontroller  410 , relay  420 , power source  430  and low frequency horn  470  are all located within housing  600 . The first led  450  is located beneath plastic covering  650  so as to provide light in all directions for egress. The second LED  460  is located behind the translucent stylized fire symbol  660  (alternatively, the second LED  460  may also be located within housing  650 ). The housing  600  also includes a clock display  690  and associated control button panel  691  and hence can also serve as an alarm clock in some embodiments.  FIG. 7  illustrates a bed shaker housing  770  that is connected to the relay within housing  600  by a power cord (not shown in  FIG. 6  or  7 ). 
   The above-described embodiments are set forth for illustration purposes only and should not be understood to limit the invention. Many modifications to the above-described embodiments will be readily apparent to those of skill in the art. For example, a tactile stimulation device other than a bed shaker may be utilized. Additionally, switching devices such as relays, solenoids, and other types of switching devices may be used in place of the power FET to control activation of the bed shaker. Audible devices such as a low frequency buzzer may be used in place of the low frequency horn discussed herein. Moreover, other non-continuous or interrupted repeating patterns may be used in place of the T-3 pattern. For example, a repeating temporal pattern consisting of more “on” periods than “off” periods (or, alternatively, short and long “on” periods separated by short “off” periods) can also be used. All such modifications are intended to be within the scope of the invention.