Abstract:
A thermoelectric device comprising an elongated panel, formed of a thermally insulating material, and having a plurality of thermoelectric elements comprising compacted conductors inside the insulating material and expanded conductors outside the insulating material is combined with other layers for leakage current interception, bodily fluid absorption, and pillars that preserve pressure re-distribution. The thermoelectric device may be integrated into a variety of surfaces or enclosures needing heating or cooling and manufactured using pre-existing automated equipment.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from U.S. Provisional Application Ser. Nos. 61/680,405, files Aug. 7, 2012, and No. 61/716,671, filed Oct. 22, 2012, the contents of which are incorporated hereby reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    In our earlier U.S. patent applications Ser. Nos. 13/101,015 filed May 4, 2011 and Ser. No. 13/394,288 filed Mar. 5,2012 and PCT Application Serial Nos. PCT/US1 1/51227 filed Sep. 12, 2011 and PCT/US12/45443 filed Jul. 3, 2012, we describe a thermoelectric heating and cooling system comprising a connected string of thermoelectric elements woven or stuffed or layered into an insulating panel, which may be comprised of a soft material like foam, memory foam, bailing, or natural fabrics. A conductor material is expanded on either side of the panel to distribute heat on one side and cooling on the other. Such a material or surface upgraded with thermoelectric heating and cooling in this manner is called a distributed thermoelectric panel. In our earlier applications, integration of that insulating panel within mattresses, chairs, and blankets was also described. The end result was a relatively low cost, uniformly distributed addition of heating and cooling to bedding, seats, blankets, and other products. 
       SUMMARY OF THE INVENTION 
       [0003]    The present invention provides various enhancements and improvements to heated and cooled products over the prior art, and also integration of thermoelectric heating and cooling panels into seat cushions, wheelchairs, hospital beds and bed tops, and pet beds. In addition, the present invention provides enhancements and improvements to the manufacturing of components of distributed thermoelectric panels for use in a variety of these and other products. Finally, the present invention provides improvements in the power delivery of distributed thermoelectric systems for increased mobility. 
         [0004]    More particularly, in accordance with the present invention, we provide a distributed thermoelectric heating and cooling panel for use in hospital beds and wheelchairs that achieves low leakage current, compatibility with incontinence pads, and preservation of pressure distribution of underlying support surfaces. We provide a process for automated manufacturing of the components needed for distributed thermoelectric products utilizing both expandable stranded wires and flexible circuit configurations. We provide a heated and cooled seat topper that maintains the original and arbitrary shape of a seat cushion. Finally, we provide an elevated pet bed with heating and cooling for use by animals. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    Further features and advantages of the present invention will be seen from the following detailed description, taken in conjunction with the accompanying drawings, wherein like numerals depict like parts, and wherein 
           [0006]      FIG. 1  schematically illustrates a hospital bed with low leakage current; 
           [0007]      FIG. 2  schematically illustrates a hospital bed compatible with an incontinence pad; 
           [0008]      FIG. 3  schematically illustrates a hospital bed that maintains pressure redistribution; 
           [0009]      FIG. 4  illustrates a housing for a control electronics and fan for the thermoelectric panel of the hospital bed in  FIGS. 1-3 ; 
           [0010]      FIG. 5  schematically illustrates an automated process for manufacturing the thermoelectric string and panel wherein the string utilizes stranded wire; 
           [0011]      FIG. 6  schematically illustrates an automated process for manufacturing the thermoelectric string wherein the string utilizes flexible circuit material; 
           [0012]      FIG. 7  schematically illustrates how power may be delivered wirelessly to a thermoelectric panel for increased mobility; 
           [0013]      FIG. 8  schematically illustrates how power may be delivered by movable contacts to a thermoelectric panel for increased mobility; 
           [0014]      FIGS. 9A and 9B  schematically illustrate how the thermoelectric panel may be integrated into a seat cushion or bed top; 
           [0015]      FIG. 10  schematically illustrates how the thermoelectric panel may be integrated into an elevated pet bed for animal use. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]      FIG. 1  shows a hospital bed that is comprised of a distributed thermoelectric string containing expanded link wires  101 , thermoelectric elements  103 , and expanded loop wires  102 . An electrical current flowing through the thermoelectric elements  103  causes heat to be moved to or from the bed surface depending on the direction of the current. The insulating foam  105 , in addition to the sting, comprises the thermoelectric panel, which is also the top layer of the bed surface. A spacer mesh layer  106  underneath provides porous channel for a fan  112  to move air from the inlet  109  to the outlet  110 , such air flows over the loops  102  to remove or insert heat from or to, respectively, the environment. The thermoelectric panel and air-flow layer are situated on top of a standard hospital mattress  114  supported by a frame  115 . A box  111  housing the electronics, controls, power supply and fan  112  connects to the spacer mesh through a slot  116 . Temperature sensors or over-temperature switches  113  or other devices turn-off or facilitate turning off the power when unsafe conditions are reached may be located at various positions. These sensors may also be used to control the bed surface to a constant temperature for thermostatic control. Without limitation, the distribution of the thermoelectric elements  103  may have varying density, or be placed in zones with separate or common temperature controls to optimize the system for the patient. Because the requirement for very low leakage current that could be experienced by patients in a hospital under fault conditions, an electrically conducting sheet  108  is situated between the patient and the thermoelectric string. This conducting sheet will preferentially divert any electrical current and minimize the remaining current that can flow through the patient should the waterproof cover  107  be compromised. The conducting sheet is preferably a metallized fabric that stretches in all four lateral directions in order to conform to the contour of the patient&#39;s body while lying on the bed. This conducting sheet with these properties is available from Less EMF Inc. and other suppliers. Without limitation, other conductive sheets could also serve this purpose such as screen, metal mesh, metallized mesh, and other materials containing metal or carbon. 
         [0017]      FIG. 2  shows how the hospital bed of  FIG. 1  is made compatible with an incontinence pad  201 . In order to achieve the desired cooling of the skin to prevent pressure ulcers and perspiration, the layers separating the patient&#39;s body from the thermoelectric links  101  should be as thin as possible. Standard incontinence pads used in hospitals have thick absorption materials for bodily fluids. The incontinence pad  201  in  FIG. 2  has thick areas  202  placed between the thermoelectric links. These thick areas act as fluid reservoirs and allow the portions of the incontinence pad  201  on top of the links  101  to be much thinner. Without limitation, these thick reservoir areas could be in an array or in parallel troughs located throughout the appropriate portion of the bed. 
         [0018]    Many hospital beds have pressure redistribution characteristics to prevent or reduce the incidence of pressure ulcers. Some of these beds alternate pressure between two or more sets of supporting areas to prevent any one portion of the body from being subjected to high pressure for too long. Other beds have an array of mushroom shapes of foam in order to distribute pressure as much as possible. Still other beds have an array of air bladders in which air may flow from one bladder to the others to balance the pressure distribution. Cooling of the skin has been shown to further prevent or decrease the incidence of pressure ulcers, beyond the benefits of pressure-redistribution alone. Hence, a need exists to provide a cooling layer that retains the pressure distribution characteristics of the underlying surface. 
         [0019]      FIG. 3  shows how the thermoelectric panel  105  is mounted on a matrix of spaced-apart support islands  301 . These islands are able to displace vertically independent of each other. Even if the island  301  material is hard, their small size and independent movement allows for the pressure distribution to be retained. The spaces between the islands  302  permit airflow from the inlet  109  to the outlet  110 . These islands may be comprised of spacer mesh, closed-cell foam, open cell foam, rubber, plastic, air balloons, fluid bladders, gels, or any other appropriate material. In the case of bladders, the fluid may be gel, oil, grease, wax, water, air, or other suitable liquid or gas. The thermoelectric panel  105  with the air flow layer comprising pillars  301  is placed on top of an existing pressure redistribution surface  302 . Without limitation, the pressure redistribution surface  302  could be comprised of contoured foam, honeycomb gel, alternating pressure mechanisms, air bladder array, viscous fluid bag, or any other surface. These surfaces are available from Roho, Hill-Rom, Stryker, Sunrise, Pride Mobility and many others and apply to seating bedding including wheelchairs, hospital beds, and operating tables. 
         [0020]      FIG. 4  shows a how the electromechanical components required for the operation of the thermoelectric panel may be housed in a single box  111 . This box  111  has room for the power supply  403 , the fan  112 , and control electronics  402 . The control electronics  402  provides for the functions of turning on and off  404 , selecting the temperature or cooling power level  405 , indicating the cooling intensity or temperature  406  with lights, and indicating fault conditions  407  such as over temperature or component failure. The box has a slot  116  for the spacer mesh or, without limitation, other channel for airflow and hooks  401  for hanging the box. 
         [0021]    With the cooling power provided by each thermoelectric chip available today, typically hundreds of such chips are needed in a heated and cooled product. The thermoelectric string also needs to consist of hundreds of segments of expandable conductors such as stranded wire and hundreds of strain reliefs. Inserting each thermoelectric junction individually requires hundreds of insertions into the insulating and airflow layers. Hence, the need exists to automate the process for fabricating the thermoelectric string and for inserting the string into the insulator to make a thermoelectric panel. 
         [0022]      FIG. 5  shows how the fabrication of the thermoelectric panel is achieved with three common automated machines that are readily available today. The first machine  501  cuts lengths of stranded wire and crimps a ferrule onto each end. The output of this machine is stranded wire segments with well-defined ends. Machines of this type are available from Schluniger and others. 
         [0023]    The second machine  502  in  FIG. 5  is one that makes circuit boards. This machine  502  has the ability to dispense glue, dispense solder, robotically place chips and other electronics components, and then flow the solder in an oven with a controlled temperature profile. To make a thermoelectric string, these functions are performed to generate strips  504  of thermoelectric junctions  103 . The stranded wire links  101  are placed from strip  504  to another strip  504  and stranded wire loops  102  are placed on the outsides of the strips  504 . Without limitation, groups of the links  101  and groups of the loops  102  may be placed manually or robotically in a carrier with comb-like slots to facilitate alignment of the ends of the links to the solder pads on the strips  504 . The combination of links  101 , loops  102 , and strip  504  are moved through the reflow oven to melt and then harden the solder. After singulating the strips  504  into connected but individual thermoelectric junctions  103 , a thermoelectric string is produced. 
         [0024]    The third machine in  FIG. 5  contains an array of sharp tubes  503  that is capable of puncturing many holes in the insulating layer simultaneously. This machine also has an array of holes  504  on top and bottom to guide the tubes and hold the insulating material in place, and a pneumatic or other system to generate the forces needed for complete puncture and insertion. Once the array of tubes has completely penetrated the insulating material, the loop  102  ends of the thermoelectric string are placed in the tubes either manually or robotically. Then, the array of tubes is removed in the opposite direction as it was inserted. A full thermoelectric panel is produced with all insertions accomplished simultaneously. 
         [0025]      FIG. 6  shows another method for automating the production of the thermoelectric ribbon. In this case, a flexible circuit material  601  is used to replace both the stranded wires and the rigid strips of  FIG. 5 . One objective of the method shown in  FIG. 6  is to not require etching of copper or patterning of the substrate.  FIG. 6  Step  1  is a sheet of flexible circuit material  601  such as copper plated on a polyimide substrate. Without limitation, the flexible layer could be polyester, Mylar, or other suitable material.  FIG. 6  Step  2  illustrates the flex material  601  after holes  602 ,  603 , and  604  have been punched in a press or other suitable machine. Holes  602  on each corner are for registration and mounting of the board in a fixture, facilitating placement and alignment. Holes  603  remove the electrical connection between the ends of the chips that are placed in a later step. Holes  604  are for mounting and gripping of a strain relief that prevents large force disturbances from damaging the chips.  FIG. 6  Step  3  shows a strain relief  605  made from epoxy or other hard or hardening material placed on the back of the flex circuit material. This strain relief  605  may be further foil led into or inserted into the gripping holes  604  for additional strain-relieving strength.  FIG. 6 . Step  4  shows the placement of solder paste  605  on copper pads in preparation for placement of the thermoelectric chips in a later step.  FIG. 6  Step  5  shows the placement of n-type thermoelectric chips  607  and p-type thermoelectric chips  608  in an alternating fashion on the flex circuit material and adjacent to the solder paste placements  606 . The assembly of  FIG. 6  Step  5  is then processed in a solder reflow oven in which the solder paste forms a hard eutectic bond with the ends of the chips and with the copper pads. Without limitation, the epoxy or other glue placed in Step  3  may be cured after Step  5  in the same reflow oven.  FIG. 6  Step  6  shows a final cut  609  into strips that represents a two dimensional thermoelectric ribbon that is ready for insertion into  105  as indicated in  FIG. 6  Step  7 . The insertion process achieves a back-to-back placement of the n- and p-type thermoelectric chips  607  and  608 . The thermoelectric panel of  FIG. 6  Step  7  now resembles the distributed thermoelectric panel that can be used for a seat cushion, bed surface, refrigerator wall, beverage wrapper, or other product needing heating or cooling and/or the ability to switch from one to the other. 
         [0026]    Distributed thermoelectric panels using this invention and others by the same inventors enable the addition of heating and cooling to any seating or sleeping surface. However, many such surfaces require mobility, such as office chairs on wheels. These products require delivery of power to the panel using wireless or other means that does not inhibit or restrict the mobility.  FIG. 7  shows one configuration wherein wireless power is delivered to the thermoelectric panel onside of chair  707 . Wireless power devices available from PowerMat, Qualcomm, WiTricity and others deliver wireless power to mobile devices such as cellphones and automobiles. These wireless power transmitters  701  and  702  deliver power to a corresponding wireless receiver inside of a mobile device  703 . The power level required for a thermoelectric panel is greater than  701  for cellphones, but less than  702  for charging batteries in an automobile. Hence, it is expected that either device could be scaled as needed to power an office chair  707 , for example. 
         [0027]      FIG. 8  shows another embodiment to permit mobility of products containing thermoelectric panels. In this case, conductive brushes  804  slide in contact with an underlying mat  801  containing alternating conducting electrodes  802  for a power supply voltage and  803  for ground. Without limitation, a plurality of brushes  804  are mounted on the ends of the spider  806  or on the wheels of any mobile device containing a distributed thermoelectric panel. As long as at least one of the brushes  804  is in contact with the power supply voltage electrodes  802  and at least one other brush is in contact with ground electrodes  803 , power voltage yin  805  may be delivered to the thermoelectric panel in the chair using the diode array circuit in  FIG. 8 . All of the electrodes  802  and  803  are electrically connected to both ends of the diode array  802 , and the rectification function of the diodes insures that power Vin  805  flows from the power supply source to ground. 
         [0028]    One application for heated and cooled seating is a seat or back cushion that is sized comparably to such cushions readily available and powered using a cord or a battery. Such a cushion is illustrated in  FIGS. 9A and 9B . The air inlet  109  is in the front for a seat bottom cushion or at the top for a seat back cushion. Without limitation, the air inlet could be partially or wholly the distributed porosity of the cover  107 . The thermoelectric panel  105  is placed on top of a spacer mesh airflow layer  102 . Blower fan  904  is located in the back of the seat bottom cushion or the lower end of a seat back cushion. The air is pulled from the inlet  109  by the blower fan and exhausted to air outlet  110 . Depending on the arrangement of the seat cushion, the preferred direction of the exhaust  110  might be blocked, so alternative outlets  901  may be added which have different directions of airflow. A cover  107  separates the seat surface from the wires  101  of the thermoelectric panel. For purposes of comfort and performance, the cover  107  may comprise soft but thermally conductive material such as carbon fibers, glycerin, gel, or unexpanded polyurethane. The entire heating and cooling system may be contained within the size and shape of a conventional seat cushion. 
         [0029]      FIG. 10  shows a heated and cooled bed for a pet or other animal for comfort indoors or outdoors. Many existing pet beds are elevated to provide ventilation from underneath. In  FIG. 10 , the elevated support layer  952  and frame  953  and  954  are retained. The thermoelectric wires  101  are brought through to the top of the support layer  952  or are in good contact from underneath. The air inlet  109  may be some of or all of the perimeter of the spacer-mesh  106  with fan  904  pulling the air from these inlets to the outlet  110 . Cover  951  separates the pet from the wires  101  of the thermoelectric panel. 
         [0030]    Various changes may be made without departure from the spirit and scope of the present invention.