Abstract:
A warning device for the prevention of pressure sores and circulation problems from prolonged inactivity includes a sensor positioned in a pad to detect the weight of a user on the pad. A sitting timer measures the amount of time the user has continuously sat on the pad, and an alarm activated by the warning device when the user has continuously sat on the pad in excess of a first predetermined limit, wherein the alarm includes a visual alarm mechanism, an auditory alarm mechanism, and a sensory alarm mechanism. A standing timer is started when the user&#39;s weight is removed from the pad and measuring the amount of time the user has been off of the pad. The alarm is reactivated if the sensor detects the user&#39;s weight reapplied to the pad before the standing timer has expired.

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates generally to an apparatus and method for the prevention of pressure sores and circulation problems from prolonged inactivity. More particularly, the present application involves a reminder that alerts an individual of the need to get up and move about to avoid the formation of pressure sores and circulatory issues. 
     BACKGROUND OF THE INVENTION 
     Prolonged sitting, reclining or laying in the same position is known to present issues that can be harmful, such as bedsores, ulcers and issues relating to blood circulation, such as blood clots. In many instances, however, people are subjected to prolonged periods of inactivity due to age, infirmity, illness, surgery or other conditions. People who may be prone to these prolonged periods in a single position, such as sitting in a wheel chair or laying in a hospital bed may need to be alerted after a certain amount of time to stand or move about to prevent the formation of bedsores, ulcers, blood clots or similar issues. 
     There have been previous attempts to develop devices to warn patients of prolonged periods without movement. One such device is described in U.S. Pat. No. 4,554,930 issued on Nov. 26, 1985 to Kress. Kress measures the pressure on a patient&#39;s skin and then warns the patient before the pressure has been applied long enough to cause damage to the skin. Another device is described in U.S. Pat. No. 7,504,955 issued on Mar. 17, 2009 to Overturf. It also detects the pressure applied by a user to a particular area and warns the user when the pressure has been applied for a predetermined amount of time. Overturf further includes a mechanism to alter the inclination of the patient, thus changing the relative pressure points. 
     These and other prior art devices suffer from a number of deficiencies. First, in order to ensure that potential injuries or issues are avoided from prolonged periods of pressure, the patient or user needs to keep the pressure removed from the affected area for a minimum amount of time. Reapplication of the pressure too soon to the affected area can have deleterious affects. None of the prior art devices monitor the length of time the patient or user has stayed off of the relevant pressure points and none are able to warn the patient if they sit or lay down too quickly after getting up. Further, the prior art devices are unable to account for patients who get up before being warned. The prior art devices work on fixed cycles and are unable to adjust their operation to account for patients moving before they have been warned by the device. 
     BRIEF SUMMARY OF THE INVENTION 
     To overcome the deficiencies of the prior art, a warning device is described that in preferred embodiments includes a sensor positioned to detect the weight of a user in an area of interest. A first timer measures the amount of time the user has been positioned in the area of interest. An alarm is activated by the warning device when the user has been positioned in the area of interest in excess of a first predetermined limit, and a second timer measuring the amount of time the user has been out of the area of interest, wherein the alarm is reactivated if the sensor detects weight in the area of interest before a second predetermined limit has been reached by the second timer. 
     In an alternate embodiment, a method for warning a user to protect against prolonged sitting is described. The method includes detecting the presence of the user when the user&#39;s bodyweight is applied to an area of interest, starting a sitting timer, and monitoring the area of interest to detect when the user&#39;s bodyweight is removed from the area of interest. An alarm is activated in the event the user has not moved before the expiration of a sitting timer, and a standing timer is started when the user has moved from the area of interest. The alarm is reactivated if the user&#39;s bodyweight is reapplied to the area of interest before the expiration of a standing timer. 
     The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view of an embodiment of a cushion according to the present invention; 
         FIG. 2  is a simplified block diagram of an embodiment of circuit according to the present invention; and 
         FIG. 3  is a flow chart illustrating a preferred method of operating a warning device in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Many elderly or people with medical issues have a tendency to remain in the same position for prolonged periods because movement is made difficult by the age or medical conditions. Sitting or laying in the same position for prolonged periods can lead to additional issues such as bedsores, ulcers, circulatory problems and blood clots. One way to prevent these problems is to get those that are able to stand and move periodically so that pressure is not applied to the same region for extended periods and blood circulation is promoted. 
     The present invention describes a system and method for preventing the problems associated with patients who are susceptible to spending long periods in sitting or laying positions. Embodiments of the present invention include a cushion or mat that detects when a person sits or lays on it. Upon detection, the device of the present invention activates a timer that warns the patient when they have been sitting or laying too long. The cushion or mat of the present invention can be made to accommodate any particular position such as sitting, reclining, or laying down or any piece of equipment or furniture, such as a chair, wheelchair, bed, or sofa. 
     Referring now to  FIG. 1 , an embodiment of a warning device  10  according to the concepts of the present invention is described. Warning device  10  includes cushion  11 . As described, cushion  11  can be chosen for any particular application and can be made of any suitable material. Cushion  11  includes one or more sensors  12   a ,  12   b ,  12   c ,  12   d  through  12   n . The sensors detect the presence of someone sitting or laying on cushion  11  and can be any type of suitable sensor or switch and located relative to the cushion anyplace that is appropriate for proper operation. For example, cushion  11  may be an inflatable air cushion, in which case the sensors may be pressure sensors that measure the air pressure in the cushion and detect the presence of a person by the increase in air pressure when weight is applied. Other configurations can include foam cushions, rubber mats, pillows or the like. The sensors can be switches, such as bump switches or any other type of sensor or switch that will detect the presence of weight or pressure on the cushion. 
     Sensors  12   a  through  12   n  and cushion  11  are connected to a control module  14 . In the embodiment of  FIG. 1 , control module  14  is shown external to cushion  11  and operatively connected by cord or wires  13 , but it would be apparent to anyone skilled in the art that control module  14  can be located anywhere relative to cushion  11  including being incorporated inside cushion  11 . Further, the connection could be integral, wired or wireless without departing from the scope of the present invention. 
     Control module  14  includes the logic to control warning device  10  and may include one or more alarms, such as a visual alarm  17  which may be a flashing light, or an auditory alarm, using speaker  16  to warn the user. Other types of alarms are well within the scope of the present invention, such as a sensory alarm, which could be a vibrator such as is used in mobile phones. Control module  14  may also include an on/off switch  15 . Power for the warning device  10  could be supplied by batteries or by plugging warning device  10  into an outlet. 
     Referring now to  FIG. 2 , an embodiment of the electronics used to control warning device  10  is described. Electronics  20  include one or more sensors  12   a ,  12   b ,  12   c , through  12   n , used to detect the presence of a person on the cushion through weight or pressure, as described above. The sensors are connected to controller  22  which includes the program and/or logic for implementing the warning program. Controller  22  can be implemented either on a microprocessor or other programmable device or can be implemented with discrete logic elements. 
     Controller  22  includes logic  23  which monitors and controls the sensors and other elements of warning device  10 . Logic  23  is connected to at least two timers used to monitor the user&#39;s activities. A sitting timer  25  is activated when the user sits or lays on the cushion as detected by sensors  12   a  through  12   n . Sitting timer  25  is monitored by the logic, and when logic  23  detects that it has reached a predetermined limit, logic  23  actives an alarm to warn the user that they should move or stand to relieve pressure points and promote blood circulation. A standing timer is activated after the logic detects that the person has stood up and measures the amount of time the user is off of the cushion. If the user sits back down before the standing timer has reached a predetermined threshold, the logic again activates the user to warn them that they have not been moving or standing for long enough to relieve the skin pressure or to promote circulation. 
     The alarms used by Warning device  10  can be any mechanism sufficient to gain the attention of the user. In a preferred embodiment, warning device  10  employs multiple alarms of different types to ensure the user is alerted. The different types of alarms work with different senses of the user to make sure that the warning is understood. For example, in the embodiment of  FIG. 2 , the warning device  10  uses a visual alarm  27 , which can be one or more lights, such as LEDs, and those lights may be made to flash or pulse. The device also uses an auditory alarm  28 , such as a speaker playing an alarm or a prerecorded message to the user. The device may also included a sensory alarm  29  that is capable of being felt by the user, such as a vibrator. The use of multiple, different alarms also allows the warning device to be used by patients that may have other disabilities such as blindness, deafness, or neuropathy. The alarms may be located in the cushion  11 , control module  14  or any other location that serves to alert the user. 
     Logic  23  may be connected to a memory  24  which can be used to hold patient specific parameters used to vary or adjust the operation of warning device  10 . For example, a younger person, or a person with only a temporary disability may not need to move as often as an older or more permanently disabled person. Therefore, the warning device need not warn the person to move or stand up as often and that person may not need to be off the cushion for as long a period and may otherwise be necessary. 
     Referring now to  FIG. 3 , an embodiment of a method according to the present invention is described. Method  30  is a preferred method for operating a warning device such as that described in  FIGS. 1 and 2 . Method  30  begins with the entry of any patient specific parameters  31 . These parameters can be used to set the maximum sitting time and minimum standing time based on any relevant factors. Next, the timers are reset or initialized  32 . The method then waits until the presence of a user is detected  33 , such as by weight being applied to cushion  11  from  FIG. 1 , thereby activating one or more sensors  12   a  through  12   n.    
     Once the presence of a user is detected, the sitting timer is started  34 . The method then monitors the presence of the user  35 . If the user stands up or removes his or her weight from the cushion before the sitting timer reaches a predetermined limit, the method proceeds to start the standing timer  40 , as will be discussed in greater detail below. If the user has not stood up, the sitting timer is monitored  36 . If the sitting timer reaches a predetermined time without the user standing, the alarm mechanism is activated  37 . Once the alarm is activated, the method again monitors to see if the patient has stood or removed pressure from the cushion  38 . Once the user stands, the alarm is turned off  39 , and the standing timer is started  40 . 
     The method then monitors to see, relative to the state of the standing timer  41 , when pressure is reapplied to the cushion by the patient  42 . If the standing timer expires before the patient sits down again, the method returns to the resetting of the timers  32  and waits for the user to sit  33 . If, however, the user sits down again before the standing timer is expired, the method checks to see if the sitting timer had previously expired  43 . If not, the method returns to the initial monitoring condition  35  after the patient sits down. If the sitting timer has already expired, the alarm is reactivated  44 , warning the user that they have not stood for enough time. The method then monitors to determine when the patient stands up again  45 , and when the patient stands up, the standing timer is reset  46 , the alarm is deactivated  39  and the standing timer is restarted. The method then continues as previously described. 
     While a specific embodiment of a method has been described, those skilled in the art will appreciate that variations, additions and subtractions can be made without departing from the scope of the concepts described herein. 
     Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.