Abstract:
An appliance warning system comprises a floor pad for location adjacent an appliance such that a user must stand on the floor pad in order to normally use the appliance. The floor pad has at least one switch movable between an open position when no weight pressure is detected on the floor pad and a closed position when the switch is activated by weight pressure detected on the floor pad. A transmitter is provided for transmitting a signal depending upon whether the switch is in the open or closed position. A module is located remote from the floor pad, and has a receiver for receiving the signal from the transmitter, and a control circuit connected operational between a ready state before the switch is activated to the closed position and a monitoring state after the switch is activated to the closed position. A warning device connected to the control circuit is activated by the control circuit when in the monitoring state when the control circuit determines that the switch has been in the open position for a preselected period of time after having been in the closed position. A reset switch resets the control circuit from the monitoring state to the ready state.

Description:
FIELD AND BACKGROUND OF THE INVENTION 
   The present invention relates generally to an apparatus that alerts and warns a user of an appliance such as a stove or oven, either visually, audibly or by some other sensory means, that a cooking process has been initiated and requires monitoring and attention. Over a cyclic period of time the user, such as a cook, is signaled to return to the appliance and the cooking process, and hence to the source of combustion (i.e. the stove top burners, the oven, broiler, etc.) until the cooking process is completed or otherwise terminated. In this way, the risk of accidental damage which may arise due to overheating, combustion and possible kitchen fire due to an unattended cooking process is greatly reduced. 
   Every year, thousands of people are killed or injured in house fires. Some current statistics indicate that deaths from fires and burns are the fifth most common cause of unintentional injury and deaths in the United States and the third leading cause of fatal home injury. Sources indicate that in 2006 fire departments responded to 412,500 home fires in the United States, which claimed the lives of 2,580 people (not including firefighters) and injured another 12,925, not including firefighters. Some statistics and sources also indicate that 4 out of 5 fire deaths in 2005 occurred in residences and that cooking was the primary cause of these fires. Often, for example, cooking related fires are caused by unattended utensils which may be left on heating elements or gas flames. A common scenario involves an elderly person who initiates a cooking procedure and then forgets that food is cooking because of distractions such as a long telephone conversation; disease (Alzheimer&#39;s is an example), other impairment or just simple forgetfulness and absent-mindedness. Furthermore, unattended food left cooking on a burner may dry and overheat, and this scenario can lead to combustion and smoke. If cooking oil is involved, combustion can quickly result and produce an uncontrollable fire in very little time. 
   One solution to this problem is an inexpensive apparatus that (1) directly detects a person&#39;s or user&#39;s presence in front of a cooking appliance before a cooking procedure is initiated, (2) automatically monitors a user&#39;s attention to the cooking process, and (3) automatically warns with an alarm or other signal the user if the cooking process is left unattended. 
   Some U.S. patents which relate to safety devices in this area are mentioned below. Naugle (U.S. Pat. No. 4,255,669) describes a sensing apparatus for monitoring the operation of an electrical appliance. Nashawaty (U.S. Pat. No. 4,446,455) describes an alarm system for use in a stove having a burner and control device for turning the burner on and off the burner, including an audio/visual alarm device and an alarm circuit for activating the alarm device. Lipscher (U.S. Pat. No. 4,577,181) describes an alarm system for an electric range which detects when a burner is energized without a utensil in place on the burner. 
   Ekblad (U.S. Pat. No. 4,775,913) describes a control device for controlling the operation of an object of cooking such as a stove or the like. The presence of a user in the area of the stove is detected. When the user is present, the stove operation is enabled. Sciscoe (U.S. Pat. No. 4,866,427) describes a temperature alarm for attachment around the exterior of the flue pipe of a wood-burning or similar stove, with alarm activation temperature selected by slidable adjustment along the flue pipe. Ljunggren (U.S. Pat. No. 5,073,701) describes an arrangement in a range, a cooking hob or the like having at least one electrically heated hot plate and/or oven, comprising a manually operable setting system for the setting of a desired power or temperature for the hot plate or the oven. 
   McLean (U.S. Pat. No. 5,608,378) describes a fire-preventing warning system for alerting an occupant leaving the premises that a stove burner is on. Neil (U.S. Pat. No. 5,608,383) describes an automatic temperature alarm system for alerting an operator of a heated apparatus that the apparatus has been heated and untouched for an excessive period of time. Clizbe (U.S. Pat. No. 5,693,245) describes an integral electric range surface burner control switch user interface made up of two components. Vaillancourt (U.S. Pat. No. 5,717,188) describes a safety device for electric stoves and ovens. Devries (U.S. Pat. No. 5,939,992) describes a safety apparatus for electric appliances which includes a sensor for sensing that an electric appliance is operating. An alarm coupled with the sensor. Cheng (U.S. Pat. No. 5,945,017) describes an electric or gas burner that can be improved by the installation of an automated fire safety device that first determines whether the burner is being attended. Rak (U.S. Pat. No. 6,130,413) describes a safety device for use in conjunction with an electric cooking stove. Aldridge (U.S. Pat. No. 6,140,620) describes a device for disconnecting an electric appliance or a component thereof from a source of electricity. Hoellerich (U.S. Pat. No. 6,294,994) describes an attendance monitoring apparatus for an appliance, such as an electrical appliance. Klass (U.S. Pat. No. 7,002,109) describes an invention to assure the safety in use of an electric range. 
   SUMMARY OF THE INVENTION 
   According to one aspect of the invention, there is provided an appliance warning system comprising: a floor pad for location adjacent an appliance such that a user must stand on the floor pad in order to normally use the appliance; at least one switch formed in or on the floor pad, the switch being sensitive to weight pressure on the floor pad, the switch being movable between an open position when no weight pressure is detected on the floor pad and a closed position when the switch is activated by weight pressure detected on the floor pad; a control circuit in or on the floor pad and connected to the switch for determining when the switch is in the open position or the closed position, the control circuit being operational between a ready state before the switch is activated from the open position to the closed position and a monitoring state after the switch is activated to the closed position; a warning device connected to the control circuit, the warning device being activated by the control circuit when in the monitoring state when the control circuit determines that the switch has been in the open position for a preselected period of time after having been in the closed position; and a reset switch on the floor pad for resetting the control circuit from the monitoring state to the ready state. 
   Preferably, the floor pad is substantially rectangular and the switch and control circuit are embedded in the floor pad. In one form, the at least one switch comprises a plurality of momentary switches embedded in the floor pad. 
   Preferably, the control circuit restarts the preselected period of time when the switch is closed during the monitoring state. The reset switch may be located near an edge of the floor pad and is activated by the user with a foot. Further, the warning device may be selected from the group consisting of: piezo crystal, a bell, a buzzer, a speaker, a horn, a strobe light, or any combination thereof. 
   According to another aspect of the invention, there is provided an appliance warning system comprising: a floor pad for location adjacent an appliance such that a user must stand on the floor pad in order to normally use the appliance, the floor pad having at least one switch formed in or on the floor pad which is movable between an open position when no weight pressure is detected on the floor pad and a closed position when the switch is activated by weight pressure detected on the floor pad, and a transmitter for transmitting a signal depending upon whether the switch is in the open or closed position; a module remote from the floor pad, the module comprising a receiver for receiving the signal from the transmitter, and a control circuit connected to the receiver and operational between a ready state before the switch is activated from the open position to the closed position and a monitoring state after the switch is activated to the closed position; a warning device connected to the control circuit, the warning device being activated by the control circuit when in the monitoring state when the control circuit determines that the switch has been in the open position for a preselected period of time after having been in the closed position; and a reset switch for resetting the control circuit from the monitoring state to the ready state. 
   The reset switch may be located on the floor pad and/or on the module. The module may powered by an AC power source, or by a DC power source. 
   Preferably, the control circuit restarts the preselected period of time when the switch is closed during the monitoring state. The reset switch may be located near an edge of the floor pad and is activated by the user with a foot. 
   In one embodiment the module further comprises a power line carrier circuit transmitter for transmitting signals to selected devices connected to an electrical system which supplies the module with power. The power line carrier circuit may be an X-10 power line carrier which superimposes a 120 Hz coded signal over existing 60 Hz Ac wiring in the electrical system. 
   According to another aspect of the invention, there is provided a method of warning when an appliance remains unattended, the method comprising: placing a floor pad adjacent an appliance such that a user must stand on the floor pad in order to normally use the appliance, the floor pad having at least one switch which is sensitive to weight pressure on the floor pad, the switch being movable between an open position when no weight pressure is detected on the floor pad and a closed position when the switch is activated by weight pressure detected on the floor pad; placing a control circuit in, on or near the floor pad and connecting the control circuit to the switch in order to determine when the switch is in the open position or the closed position, the control circuit being operational between a ready state before the switch is activated from the open position to the closed position and a monitoring state after the switch is activated to the closed position; activating a warning device connected to the control circuit when the control circuit is in the monitoring state and the control circuit determines that the switch has been in the open position for a preselected period of time after having been in the closed position; and providing a reset switch on or near the floor pad for resetting the control circuit from the monitoring state to the ready state. 
   The module may be located remote from the floor pad and contains the control circuit and the warning device, and a transmitter is placed in the floor pad and a receiver is placed in the module to facilitate communication between the switch and the control circuit. Further, a power line carrier transmitter may be integrated into the control circuit for activating remote devices through an electrical supply system simultaneously with the warning device. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
       FIG. 1  is a perspective view of an appliance in the form a stove and warning device in accordance with on embodiment of the present invention; 
       FIG. 2  is a detailed perspective view of a floor pad in accordance with the warning system of the invention; 
       FIG. 3  is a perspective view of a floor pad and module box on the warning system in accordance with another embodiment of the present invention; and 
       FIG. 4  is a detailed perspective view of a module of the warning system in accordance with the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   With reference to  FIG. 1  of the drawings, in one embodiment of the invention, the invention comprises a sensing device  10  including a floor pad  12 . The floor pad  12  will preferably, but not necessarily, be sized and configured with dimensions approximately equivalent to the floor space typically required to use the cooking appliance  14 . The floor pad  12  may be rectangular, semi-lunar, or another shape so long as a person using the cooking appliance  14  must normally stand on it in order to use the appliance  14 . 
   The floor pad  12  is preferably constructed of a suitable polymeric thermoplastic, rubber, foam, gel or combination thereof so a resilient, shock absorbing surface is provided for comfort and functionality. The floor pad  12  contains a pressure sensitive, normally open, momentary switch or switches  16  (such as membrane switches) interspersed equally and imbedded within the floor pad  12  so that a person standing on the pad  12  must depresses one or more switches  16 , as shown in  FIG. 2  of the drawings. Any suitable arrangement incorporating electronic, electro mechanical, mechanical or electro-optical methods may be employed to configure a weight sensitive switch  16  that is momentary and normally open. The weight required to depress and momentarily close a switch  16 , or signal the presence of a load on the floor pad  12 , would fall within a range equivalent to the average human weight range, for example, 75 to 300 lbs. 
   Once a switch  16  of the floor pad  12  is depressed and thereby closed, an internal (within the floor pad  12 ) or external (outside the floor pad  12 ) populated printed circuit board or PCB (see  FIG. 2 ) is triggered or activated by an appropriate signal form the floor pad  12  switches  16 . The PCB  18  contains a circuit that monitors the open or closed condition of the floor pad  12  switch  16 , a timing circuit, a power status circuit, a ON-OFF-READY indicating circuit, an alarm or signaling circuit and an electronically connected alarm or signaling device  20 , such as, for example, a piezo crystal, a bell, a buzzer, a speaker, a horn, a strobe light, an RF interface to other appliances, lights, and/or a power line carrier interface to other appliances. 
   A power supply unit  22  is provided. The electromotive force or power supply from the power supply unit  22  required to power the PCB  18  may be comprised of a replaceable dry cell battery, rechargeable battery, AC transformer or other suitable power source. 
   In one embodiment of the invention as shown in  FIGS. 1 and 2  of the drawings, the floor pad  12  switch or switches  16 , PCB  18 , power supply  22 ), and alarm  20  are completely self contained or embedded within the floor pad  12 . In this particular embodiment, a person must stand on the floor pad  12  in front of the cooking appliance  14  to initiate a cooking procedure. When the person stands on the floor pad  12 , the PCB  18  immediately detects the closed condition of the floor pad  12  switches  16  due to presence of the user, and then waits for an open condition to occur when the person leaves or steps off the floor pad  12 . Once the open condition is detected, a non-user interfaced, preset timing cycle, for example, 7 minutes (although any suitable time delay can be selected) is initiated. If the person returns and steps onto the floor pad  12  before the timing cycle of 7 minutes (or other preset time) are over, the timing cycle will reset and wait for the person to leave the floor pad  12  to begin another 7 minute timing period. Resetting of the timing cycle continues as long as the person keeps returning to the cooking appliance  14 . Eventually, one of two conditions will occur, as detailed further below. 
   Condition one: In this scenario, the person returns to the cooking appliance  14  within the selected timing cycle(s) (in this example, 7 minutes) and terminates the cooking procedure. At this point, the person depresses an optionally lighted (LED) reset switch  26  which is preferably located on the external upper surface of the floor pad  12  at a position which would not normally be stood upon by the person using the device so as to avoid inadvertent activation of the reset switch  26 . Depression of the reset switch  26  on the floor pad  12  deactivates the PCB  18  and resets the system to a READY state. In the READY state, the PCB  18  will remain inactive until the next closed position of the floor pad  12  switches  16  is detected, and a new cooking procedure is initiated. If the person terminates the cooking procedure but forgets to depress the floor pad  12  reset switch  26 , an internal alarm  20  will sound after the 7 minute timing cycle expires. The alarm  20  will continue to sound until the person returns to the floor pad  12  (and hence the cooking appliance  14 ) and resets the system to the READY state. 
   Condition two: In this scenario, the person does not return to the cooking appliance  14  during the first or subsequent timing cycle(s) within the preset time (7 minutes in the present example, but reprogrammable as required). In this case the internal alarm  20  will sound until the person returns to the cooking appliance  14  and steps onto the floor pad  12  to either continue the cooking procedure and initiate a further 7 minute countdown period, or terminate the cooking procedure by pressing down on the reset switch  26 . If neither of these events occur, the alarm  20  will continue to sound until the floor pad  12  reset switch  26  is depressed or the power available from the power supply unit  22  ( 5 ) is depleted. 
   Reference is now made to  FIG. 3  of the drawings which illustrates a further embodiment of the present invention. In this embodiment of this invention, all the electrical components are not self-contained within the floor pad  12 . Instead, the floor pad  12  contains the pressure switch or switches  16  or other electronic, electro mechanical, mechanical or electro-optical means for detecting a weight load on the pad, a power supply unit  22 , and an RF transmitter circuit  30 . The power supply unit  22  powers the RF transmitter  30  contained within the floor pad  12 . There are several ways for electronically configuring the RF circuit  30  that utilize standard, semi-custom and custom electronic components, such as ICs, resistors, capacitors, inductors, and so forth. An RF circuit  30  capable of propagating a discrete, pulsed and coded electromagnetic signal is preferred in the context of this invention. 
   The open and closed position of the floor pad  12  switches  16  are detected, processed and modulated by a circuit that is continuous with the RF transmitter circuit  30 . The modulated RF signal relays the closed or open position of the floor pad  12  switches  16  to a module  32  that is plugged into a nearby (i.e. in the kitchen if the appliance being monitored is the cooking appliance  14 )) electrical outlet. The module  32  houses a PCB  34  that includes: an RF receiver circuit  36  capable of detecting and decoding the modulated RF signal of the RF transmitter  30 , a logic circuit, a timing circuit, an alarm or signaling circuit, a power status circuit, a ON-OFF-READY circuit, a reset circuit and a electronically connected internal module alarm  38 , such as a piezo crystal, a bell, a buzzer, a speaker, a horn, a strobe light, and others, or a combination of such alarms. The PCB  34  is powered by the AC line  40 . 
   The floor pad  12  may include a transmitting antenna  43  and the module  32  may contain a receiving antenna  45 . 
   Operation of the apparatus is generally the same as the embodiment discussed above, except that the PCB  34  is external to the floor pad  12  and is remotely connected to the floor pad  12  through the RF transmission, namely the RF transmitter circuit  30  and the RF receiving circuit  36 . This embodiment has certain advantages, some of which include: (1) the PCB  34  and the alarm  38  or signaling device are AC powered and less susceptible to power failure, and (2) a higher decibel alarm or more powerful alarm may be used since power drain, as from a dry cell battery, is a negligible factor. The floor pad  12  may have a reset switch  42  which may be located on the floor pad  12  (as in the first embodiment described above), or the rest switch  44  may be located on the outside face of module  32  that is plugged into an outlet  46  near the cooking appliance  14 . Indeed, there may be both reset switches  42  and  44  within a given system in order to give the user the option of selecting one of these switches depending upon which of them may be more convenient to use in a given situation. 
   Reference is now made to  FIG. 4  of the drawings which shows a further embodiment of the invention. In this embodiment, the module  50  is very similar to the module  32  shown in  FIG. 3  of the drawings in that it also contains the PC board  52  and internal alarm or signaling circuit. Further, the operation is essentially the same as in the embodiment illustrated in  FIG. 2 , but further includes an X-10 power line carrier (PLC) circuit  56 , or a similar type of circuit capable of achieving substantially the same effect, that is able to superimpose a 120 Hz coded signal  64  over the existing 60 Hz AC wiring system  66  throughout the home or building. The superimposed signal can then control a variety of devices and appliances that are connected to the X-10 compatible receiver modules plugged into wall outlets throughout the house. Examples of devices that may be plugged into an X-10 compatible receiver module include: room lamps, strobe lights, PC controllers, high-decibel sounding devices, telephone dialers, existing light switches and receptacles, existing alarm systems, other appliances, and the like. 
   One advantage of the embodiment incorporating the X-10 compatible receiver, or a functional equivalent thereof, may be illustrated by the following example: A person initiates a cooking process and of necessity steps on and off the floor pad  12  depressing the imbedded floor pad switches  16 . The closed or open condition of the floor pad  12  switches  16  is converted to a signal by a circuit that is continuous with the RF transmitter circuit located within the floor pad  12 . The processed coded signal is then modulated and propagated as an RF signal to the module  50  that is plugged into an electrical outlet  46  near the cooking appliance, preferably somewhere in the kitchen. The RF signal is then processed by the RF receiver circuit  58  located on the PC board  52  housed within module  50 . The processed signal activates the timing circuit within the PC board  52  housed within module  50  and a timing cycle (for example, 7 minutes) is initiated. 
   When the person does not return to the cooking appliance during the first or subsequent timing cycle(s) within the preset time (optionally 7 minutes), then the internal module alarm  60  housed within module  50  begins or continues to sound until one of the following events occur: 
   (1) the person returns to the cooking appliance, steps onto the mat and continues the cooking process, thereby resetting the timer to an additional 7 minutes; 
   (2) the person returns to the cooking appliance to terminate the cooking process and then depresses the floor pad reset switch  42  or module reset switch  44  to reset the system; 
   (3) the person returns to the cooking appliance to terminate the cooking process but forgets to reset the system by depressing the floor pad reset switch  42  or module reset switch  46 , in which event the internal module alarm  60  will sound until the floor reset switch  42  or module reset switch  46  is depressed; 
   (4) the person fails to return to the cooking appliance, for example, after 3 timing cycles or 21 minutes. If the person has not returned to the cooking appliance or kitchen area to reset the system within 21 minutes the module  50  will activate one or more X-10 connected devices (i.e. room lamps, strobe lights, a PC controller, a high-decibel alarm, a bell, a siren, a horn, transceivers X-10 to RF and RF to X-10, a telephone dialer, etc.) to further alert the person or alert others such as neighbors, relatives, 911 emergency services, the fire department, as examples) of a potentially dangerous and life threatening situation. The use of X-10 or X-10 compatible interfaces becomes useful for persons having disabilities such as deafness. A bypass switch located on the module  50  may serve to bypass the audible alarm in favor of an X-10 device connected to a strobe light or multiple room lights to alert a deaf person in all signaling and alarm modes. 
   X-10 technology: X10 Power Line Carrier (PLC) technology was invented and patented in the late 1970s and opened up a whole new world of remotely controlling almost anything plugged into the electrical power line, without adding any control wiring. Basically, the X10 power line signaling technique consists of superimposing and transmitting a 120 khz coded signal on the 60 hz electrical power line. Using X10 transmitting device(s), the signal is sent over the power line to X10 receiving device(s) which are programmed with the same House and Unit code. There are 256 different standard X10 codes available (16 House codes: A through P, and 16 Unit codes:  1 - 16 ).