Abstract:
A portable compact sauna wherein a user&#39;s body is warmed to sweating primarily by direct absorption of infrared radiation. Broad infrared radiation emitters or sources are placed around the inside of a narrow cabinet so as to be in close proximity to various parts of a seated user. Fins spaced apart less than finger-width on the emitters protect the user from contact with elevated temperatures in the emitters. The emitters, which lend themselves to easy cleaning, are heated by electric infrared heaters having a unique design which eliminates extremely-low-frequency (ELF) electromagnetic field (EMF) normally generated by AC energized electrical heater elements, to provide low extremely-low frequency EMF saunas able to utilize conventional-commercial electrical-energy sources. The emitters protect the heaters. Power wires for the heaters are arranged for low ELF EMF emission, too.

Description:
0. DIVISIONAL PATENT APPLICATION  
       [0001]    This patent application is a division of patent application Ser. No. 10/079,397 filed Feb. 20, 2002 by Bernarr C. Schaeffer, James Schaeffer, and Wayne Schaeffer for “Infrared Sauna”. 
     
    
     
       1. FIELD OF THE INVENTION  
         [0002]    This invention relates to saunas, and more particularly to a portable sauna employing infrared heat.  
         2. BACKGROUND OF THE INVENTION  
         [0003]    The use of saunas to promote the formation of perspiration (sweating) for its therapeutic effects, is well known. However, the use of saunas relying primarily on the body deep absorption of infrared radiation, is not known. While the provision of a sauna cabinet per individual is known, such individual cabinets have not been compact or portable.  
           [0004]    The use of infrared heaters throughout history is well known. Humans first warmed themselves with campfires, later with fireplaces, and now with radiant floors and infrared sauna rooms. However, heretofore when using any infrared source greatly warmer than room temperature, it was difficult to protect a user from touching the hot surface (and experiencing pain or burning) without disadvantageously shielding the heat source in the process. Therefore the emitting surface was either placed far away from the user or had a bulky screen placed around it. In either case, the heater could not safely be in close proximity to the user.  
         3. PRIOR ART  
         [0005]    Books discussing saunas include “Sweat” authored by Michael Aaland and published by Capra Press, Santa Barbara, Calif. (1978); “Therapeutic Heat and Cold”, 2 nd Edition, Vol.2 of the “Physical Medicine Library” published by Elizabeth Licht, New Haven, Conn. (1972) (page 203 article “History of Therapeutic Heat” by Sidney Licht with Herman L. Kamenetz); “Light Therapeutics: A Practical Manual of Phototherapy for the Student and the Practitoner”, Revised Edition, authored by Dr. John Harvey Kellogg and published by The Good Health Publishing Co., Battle Creek, Mich. (1910); and “The Sauna is . . . ” authored by Bernhard Hillila and published by Penfield Press, 215 Brown St., Iowa City, Iowa 52245 (1988).  
           [0006]    Sidney Licht, in his article above identified, notes that in 1891, Dr. Kellogg built a rectangular cabinet with 40 lamps of 20 candle power each, and interior reflectors, in which his patients sat completely nude, with the head outside. But Kellogg&#39;s cabinets were roomy, to assure that the patient did not come in contact with the hot lamps radiation source. Thus his patient was not directly heated primarily by radiation, but rather by a combination of radiation and convection; heating by radiation being defined as the direct absorption by the body of the patient of the infra red energy emanated by the heater (lamps in Dr. Kellogg&#39;s case); and heating by convection being defined as direct contact with the body of the patient by a moving substance (air) warmed as by the lamps.  
           [0007]    Other infrared saunas are known. Typically, they are room-sized, having several heater panels imbedded in the walls far from the user or mounted behind bulky metal screen shields: in either case the heater could not safely be in proximity to the user; proximity being advantages for efficiency of heat transfer and for compactness of a heating apparatus. Such saunas do not impact the body deeply, or evenly over a large expanse of its surface area, because of the comparatively small area of the room that is covered by heaters, and because while some may be very close others are very far from the user. Moreover, a room-sized sauna is not easily portable and will not efficiently or evenly heat a human user.  
           [0008]    Non-lamp infrared heaters are known.  
           [0009]    Actually, infrared heaters are ubiquitous in industrial processing application, where various safety protocols and structures protect workers from injury in their usage. Infrared heaters for personal heating are well known in radiant floor and ceiling applications, and in baby incubators, for example, where the temperature of the heating surface is low enough, or the heater is far enough from the user, as to not be a danger.  
           [0010]    Researchers have opined that fields of electromagnetic radiation (EMFs) in the extremely low frequency (ELF) band, e.g. 60 Hz, may be harmful to the human body if they are stronger than ambient fields levels (typically, near or less than one milligauss). See, for example, the book “Cross Currents” written by William O. Becker and published by Penguin Putnam, Inc. in 1990, and the book “Currents of Death” written by Paul Brodeur and published by Simon and Schuster in 1989.  
           [0011]    Existing infrared saunas can have upwards of 25 to 50 milligauss ELF EMF impacting the body. Very expensive high-nickel content metal shields exist that absorb EMF, but have yet to be employed over high surface area infrared heaters—they are cost prohibitive.  
           [0012]    U.S. Pat. No. 5,399,996 Yates et al shows a technique for minimizing electromagnetic emissions. It uses a dummy load circuit which has an impedance equal to that of the circuit load, in a digital environment.  
         SUMMARY OF THE INVENTION  
         [0013]    Accordingly, it is an object of the invention to provide a compact sauna usable not only in the home but also in health clubs, hotels, detoxification clinics, etc.  
           [0014]    An additional object of the invention to provide a portable sauna, and one that will pass through the normal 36-inch-wide door of a conventional home.  
           [0015]    Another object of the invention is to provide a sauna which primarily heats the user directly by infrared radiation.  
           [0016]    Another object of the invention is to provide a sauna which utilizes broad infrared heat sources or emitters in close proximity to the user&#39;s various body parts.  
           [0017]    Still another object of the invention is to provide a sauna which allows the infrared heat source or emitter to be safely placed close to the user&#39;s body.  
           [0018]    Still another object of the invention is to provide a sauna using an electric infrared heater to heat the infrared heat source or emitter in close proximity to the user&#39;s body.  
           [0019]    An additional object of the invention is to provide a sauna that is easy to clean and durable in use.  
           [0020]    Yet another object of the invention is provide a sauna using conventional 110-volt 60-cycle current electric infrared heaters and yet has a low extremely-low-frequency (ELF) electromagnetic field (EMF) in it.  
           [0021]    A further object of the invention is to provide an infrared emitter and infrared heater assembly that is safe to touch while hot enough to transfer significant heat to the user.  
           [0022]    A still further object of the invention is to provide an infrared emitter and infrared heater assembly that is of programmable size, shape, color, physical strength, warm-up time, temperature, and heat-source type.  
           [0023]    A yet further object of this invention is minimize cabinet ELF EMF due to AC power wiring for the heaters.  
           [0024]    Another object of the invention is to provide an infrared emitter and infrared heater assembly that is safe and effective for such applications as very-close-range personal heaters for use in offices (e.g., under desks), at home, in factory and commercial environments, in hospitals and baby incubators, and the like.  
           [0025]    A further object of the invention is to provide a portable sauna that is inexpensive of construction and easy of manufacture.  
           [0026]    The objects of the invention are accomplished through the provision of a small sauna having safe-to-the-touch infrared emitters or sources of a large surface area surrounding the user&#39;s body on all sides. The infrared radiation sources or emitters are of a unique design. The infrared radiation source or emitter incorporates protrusions such as parallel fins spaced close enough to thwart fingers being inserted between them, and extending outward from a hot base portion (flats between the fins and main radiators) heated to elevated temperatures but which at their outer or free ends are at comfortable-to-touch temperature due to the low heat conductance of the material of which the source is constructed and to the heat loss along the depth of the fins due to radiation and air cooling. The cool-to-the-touch radiation source enables construction of a small cabinet conforming to the configuration of a person seated in it, with a plurality of infrared heat sources or emitters being located in close proximity to and around the person&#39;s body parts.  
           [0027]    The finned infrared radiation sources are easy to clean and protect their heaters behind them. A light wiping action of the finned sources is just about all that is needed to keep the sauna tidy and operational.  
           [0028]    The infrared radiation sources or emitters are heated by electric infrared heaters positioned behind them in close proximity. The use of electric infrared heaters powered by conventional 110 volt 60 cycle alternating current and positioned in close proximity to the infrared radiation sources and hence to the users, is enabled by the design of unique electric infrared heaters generating only low extremely-low-frequency (ELF) electromagnetic fields (EMFs) in the sauna by canceling them out. The unique dual electric infrared heaters may be formed of a plastic substrate on both sides of which are printed semi-conductor patterns having a) a plurality of identical electrically-resistive bars spaced apart from each other and radiating infrared energy when electrical current is passed through them, and b) a pair of longitudinal stripes extending parallel to and spaced from each other and interconnected with respective ends of the bars to have electrical connections therewith to form two thin flat planar electrical resistance heaters in very close proximity to each other; and electrically connecting them to the AC source so that the heaters are respectively wired to opposite electrical polarities. Thus a set plurality of identical bars that are spaced apart from each other and radiate infrared energy when electrical current is passed through them are mounted next to an identical set of such bars wherein electricity is simultaneously passed through in the opposite direction; the EMFs generated by corresponding bars of each set canceling each other. Of course, two single heater arrays (on separate substrates) may be juxtaposed, with opposite current flow, to achieve reduced EMF effects, too.  
           [0029]    Electric infrared heaters may also be powered by direct current, the electrical connections needing to be reversed for the respective heaters only if all electro-magnetic fields are to be minimized.  
           [0030]    Another way to heat the emitters is by circulation of a heat exchange fluid behind them, as through channels integral with the valleys or bases of the finned emitter. This would eliminate the AC EMF problem too, but entails a cumbersome structure.  
           [0031]    A feature of the invention is that it enables taking full advantage of the special heating powers of infrared radiation by relying primarily on it. Whereas steam or warm air heats only the skin of a sauna user (by conduction), strong infrared radiation soothingly penetrates the body to about one and one-half inches to more effectively and comfortably warm the body to sweating temperature and more effectively remove body toxins which primarily reside in the fatty tissues immediately under the skin. Strong infrared radiation penetrates more deeply into the body than does heat from hot air or steam, and thus causes the body to sweat at lower temperatures, accommodating users who dislike higher temperatures. Deep penetration causes weight loss in fat, not just in water.  
           [0032]    An advantage of the invention is that the close location or proximity of the infrared sources or emitters to the user&#39;s body, and the close location or proximity of the electric infrared heaters to the infrared sources, allows the walls of the sauna cabinet to be closely positioned about the user&#39;s body, resulting in a compact cabinet which not only frugally and effectively uses heat (requiring less electricity, and applying it more precisely, deeply, and intimately ), but can be dimensioned to pass through normal-width entrance doors to homes and business establishments.  
           [0033]    Low ELF EMF is insured within the cabinet also by constructing the heater power lines in extremely-low-frequency electro-magnetic-field canceling arrangements. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS OF PREFERRED EMBODIMENTS  
       [0034]    These and other objects, features and advantages of the invention will become apparent from a reading of the following detailed description of a preferred embodiment of the invention, when considered with the appended drawings wherein:  
         [0035]    [0035]FIG. 1 is a diagrammatic view in perspective of a portable sauna constructed according to the invention;  
         [0036]    [0036]FIG. 2 is an partial isometric view in perspective of the two infrared generating components of a dual infrared heater used in the sauna and showing their reversed electrical connections with an AC source to minimize ELF EMF generation;  
         [0037]    [0037]FIG. 3 is a chart depicting empirical evidence showing the high ELF EMF resulting from using single electric infrared heaters, versus the low ELF EMF resulting from using dual electric infrared heaters with reversed electrical connections;  
         [0038]    [0038]FIG. 4 is an isometric view in perspective of the infrared source or emitter for the sauna finned to block a person&#39;s body parts from contacting the portions thereof at elevated temperatures;  
         [0039]    [0039]FIG. 5 is a cross-sectional view showing a dual electric infrared heater according to the invention (1) mounted in spaced relationship via a backing panel on a cabinet wall to avoid undesirable heating of the wall, and (2) covered by the unique infrared source or emitter it heats and that presents the person with only a warm-surface tactile exposure;  
         [0040]    [0040]FIG. 6 is a diagrammatic view from the right side of the interior of a slightly modified version of the sauna shown in FIG. 1, with its door closed and showing a user seated on another type of adjustable seat;  
         [0041]    [0041]FIG. 7 is an edge sectional view of a portion of a flat panel electric infrared heater showing a pair of flat resistance-heating bars on opposite sides of an insulating substrate and through which respective side bars 60 cycle alternating current instantaneously flows in opposite directions to produce canceling ELF EMFs, and a conjoint view in perspective of the two heating bars;  
         [0042]    [0042]FIG. 8 is a sectional view of two round insulation-clad electrical wires, to show the inherently greater spacing of electrical currents in juxtaposed round wires over that of juxtaposed flat wires and hence their greater inability to cancel EMFs as effectively as flat wires of FIG. 7, and a conjoint view in perspective of the two round wires;  
         [0043]    [0043]FIG. 9 shows in enlarged detail the adjustable seat in FIG. 6.  
         [0044]    [0044]FIG. 10 is a schematic diagram of the circuits employed in the sauna.  
         [0045]    [0045]FIG. 11 is a cross-sectional view of low EMF power wiring constituted of a solid wire within a tubular wire;  
         [0046]    [0046]FIG. 12 is a cross-sectional view of even lower EMF power wiring constituted of a hollow wire within a tubular wire;  
         [0047]    [0047]FIG. 13 is a chart depicting empirical evidence showing the high EMF resulting from regular (side by side) wire for power wiring, versus the low EMF resulting from using wire-within-wire power wiring;  
         [0048]    [0048]FIG. 14 is cross-sectional view of still lowerer EMF power wiring constituted of juxtaposed solid flat wires; 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0049]    Referring now particularly to the drawings, there is shown in FIG. 1 a portable compact sauna generally indicated by the numeral  10 . The sauna  10  includes a narrow cabinet generally indicated by the numeral  12  and including a floor  14 , a right-hand side wall  16 , a left-hand side wall  18 , a rear wall  20 , a roof  22 , and an upwardly rearwardly-sloping front opening closed by a side-hinged door generally indicated by the numeral  24 . The rear wall  20  may hingedly mount at adjustable chair heights a forwardly extending seat  26  supported at its forward end upon a height-adjustable floor post  28 . The roof is cutout at  30  to receive the neck of a user seated on seat  26  adjusted to an appropriate height, leaving the user&#39;s head outside of the sauna cabinet  12 .  
         [0050]    The door  24  includes a rearwardly upwardly-curving cylindrical-like arc or front portion  32  and a right-hand siding  34  and left-hand siding  36  bridging the arc of the front portion  32 . The door  24  is hinged to the cabinet right-hand side wall  16  along the free edge of its right-hand door siding  34  as by a conventional piano hinge. The cabinet components may be made of a suitable plastic such as polyester ABS or PETG. It will be appreciated that the rearwardly upwardly-sloping front edges of the of the cabinet side walls  16  and  18  enables the cabinet when the door  24  is in closed position, to snugly accommodate in its bottom portion the horizontally-extended legs of a seated user while in its upper portion closely embracing the user&#39;s torso (see FIG. 6).  
         [0051]    A number of infrared sources or emitters are distributed about the interior surface of the cabinet. In the preferred embodiments disclosed, ten flat and broad sources are employed: five being mounted on the door  24 ; five being mounted on the cabinet walls. Door infrared sources from top to bottom are numbered  40 ,  42 ,  44 ,  46  and  48 . Cabinet right-side wall sources are numbered  50  and  52 , cabinet left-side wall sources are numbered  54  and  56 , and rear-wall source is numbered  58 .  
         [0052]    The door sources  40 - 48  are mounted indirectly on the door via an upper-and-lower-end attached panel generally indicated by the numeral  60  and following the inclination of the door  24  and bent at four different places to present five different sections or faces  62 ,  64 ,  66 ,  68 ,  70  for mounting flat, directional infrared sources at various angles to the sauna user&#39;s body parts. In general, panel  60  follows the contours of the front of a person sitting in the sauna on seat  26 . The top and bottom sections  62  and  70  of the panel are generally coplanar, and dispose flat panel sources  40  and  48  thereon to radiate infrared energy rearwardly and slightly downwardly into the sauna cabinet (FIGS. 1 and 5). Adjacent sections  64  and  68  are respectively inclined downwardly and rearwardly and respectively dispose flat panel sources  42  and  46  thereon to radiate infrared energy downwardly and rearwardly into the sauna cabinet. The central panel section  66 , interconnecting sections  64  and  68  and generally in a parallel plane with top and bottom sections  62  and  70 , mounts source  44  to radiate infrared energy somewhat downwardly and rearwardly in the sauna cabinet. Source  40  radiates the front of the upper portion of the torso of a user seated on seat  26 ; source  42  his or her thighs; source  44  the knee areas; source  46  the upper lower legs; and source  48  the lower lower legs and feet.  
         [0053]    Cabinet right-side wall  16  sources  50  and  52  radiate the right side of a user. Lower cabinet source  50  warms the outside of the right leg; source  52  the right-side of the torso.  
         [0054]    Cabinet left-side wall  18  sources  54  and  56  radiate the left side of a user. Lower cabinet source  54  warms the outside of the left leg; source  56  the left-side of the torso.  
         [0055]    Cabinet rear wall source  58  radiates the back of a user.  
         [0056]    The infrared source or emitter employed in the invention and generally indicated by the numeral  88  (FIGS. 4 and 5), is comfortable to the human touch on its exposed side. The source may be vacuum formed of a sheet of suitable plastic such as polycarbonate, and with hollow fins  90  that are spaced less than one-half inch apart (less than normal finger width and that project about one-half inch high from a base  92 . When an electric infrared heater is placed behind the finned infrared source or emitter, the flats constituting the base  92  between the fins are heated to a high infrared radiating temperature, as on the order of 200 degrees Fahrenheit or more. The chosen plastic or other material for the fins has poor heat conductance; between the cooling of the fins by radiation and air movement over their surfaces, the fin tip temperature is limited to 140 degrees F. or so even though the temperatures of the flats in the base  92  reach 200 degrees F. or so. The small spacing of the fins, less than finger width, limits the exposure of the user to the tip temperature of 140 degrees. Hence higher infrared source or emitter temperatures than heretofore practical, can be utilized. The finned infrared source may be also be deemed a cover, and so molded, for an electric infrared heater used to heat the sauna infrared source or emitter  66  base  92  to efficient infrared radiating temperature.  
         [0057]    As observed earlier, the hollow finned infrared source or emitter (and cover)  88  of FIGS. 4 and 5 may be vacuum formed from a suitable sheet of plastic. Alternatively, a solid-, and thinner-, finned infrared source or emitter may be injection molded.  
         [0058]    The electric infrared heaters for heating the infrared sources  88  may be generally of the type described in U.S. Pat. No. 4,485,297. Such a heater is formed of a plastic substrate on which was printed as by silk screening a semi-conductor pattern having a) a plurality of identical electrically-resistive bars spaced apart from each other and radiating infrared energy when electrical current is passed through them, and b) a pair of longitudinal stripes extending parallel to and spaced from each other and interconnected with respective ends of the bars to form electrical connections therewith; a metallic conductor like copper overlying each longitudinal stripe and in intimate electrical contact therewith throughout its length; a pair of plastic sheets positioned on respective sides of the substrate and pattern and hermetically sealing them; and a pair of crimp-on connectors for establishing electrical connection with the conductors.  
         [0059]    But it has been found that electric infrared heaters constructed according to the U.S. Pat. No. 4,485,297 emanate a high extremely-low-frequency (ELF) electromagnetic field (EMF), such as 25 mg at very close range. Thus a unique heater assembly which only produces a low extremely-low-frequency EMF has been invented and utilized in the sauna. The unique heater assembly mounts two thin flat planar electrical resistance heaters of the type disclosed in U.S. Pat. No. 4,485,297 in very close proximity to each other and wires them respectively to opposite AC electrical polarity. Thus the set plurality of identical bars that are spaced apart from each other and radiate infrared energy when electrical current is passed through them, are juxtaposed to an identical set of such bars so that when electricity is simultaneously passed through them in opposite directions, the ELF EMFs generated by corresponding bars of each set cancel each other near totality.  
         [0060]    In a preferred embodiment and as shown in FIG. 2, two thin flat planar electrical resistance heaters generally indicated by the numeral  72  and  74  are mounted on opposite sides of a single plastic substrate  76  of polycarbonate or the like. The conductor stripes  78  and  80 , interconnecting electrically-resistive radiating bars  79  of heater  72 , are connected one way to a source  82  of alternating current (AC), while corresponding conductor stripes  84  and  86  are connected the opposite way to the AC source  82 . Thus at any given time, current flows in opposite ways through corresponding ones of the bars of the two heaters, effectively neutralizing the EMF generated by each. This enables the dual infrared heaters to be placed close to the human body without danger of impacting the body of the user with high doses of extremely-low-frequency electromagnetic fields (ELF EMFs).  
         [0061]    As shown in the chart of FIG. 3, a significant reduction of measured EMF strength obtains from the use of a dual heater assembly over a single heater assembly. For a single circuit heater, a high extremely-low-frequency EMF of 25 milligauss may obtain within one inch of it, and of about 16 milligauss at 3 inches. For the dual circuit heater of the invention, approximately only 1 milligauss obtains at even only 1 inch distance.  
         [0062]    It will be appreciated that the electrically-resistive radiating bars  79  of heater  72  may be replaced with suitably-mounted high-resistance wiring such as nichrome, in solid, mesh or fabric construction.  
         [0063]    It will also be appreciated, as observed earlier, that the heaters may be powered with direct current, in which case the extremely-low-frequency EMF does not obtain.  
         [0064]    As per the showings of the U.S. Pat. No. 4,485,297, the dual heater of FIG. 2 above could be hermetically sealed between two sheets  84  and  86  of plastic (here polycarbonate) and crimp-on connectors employed to make electrical connections.  
         [0065]    Of course, single heater arrays on separate substrates may be juxtaposed, with corresponding electrically-resistive bars opposed and wired to opposite polarity, to achieve similar reduced EMF effects. However, best extremely-low-frequency EMF reduction is achieved by positioning the thin flat wiring or bars  72  and  74  on opposite sides of a thin substrate  76 , in a manner shown in FIG. 7.  
         [0066]    [0066]FIG. 8 shows graphically why insulated round wires cannot be as closely positioned, low extremely-low-frequency EMF-wise, as insulated flat wires; the center of conductivity for abutting insulated round wires  77  being inherently necessarily further apart than for abutting flat wires; hence round wires are less able to effect low ELF EMFs than flat wires.  
         [0067]    A specific infrared source or emitter and an electric infrared heater therefor and mounting structure assemblage, are shown in FIG. 5. A cabinet wall, such as left-side wall  18  backs up a corrugated panel  94  in which ridges  95  are arranged in correspondence with the electric infrared heaters  72  and  74  corresponding pairs of bars  79 , and the infrared source&#39;s valleys or bases  92 , to hold them snugly together. The finned infrared source or emitter  88  at its edges secures the assemblage to the cabinet wall  18  as by screws. Thus the corrugated panel ridges  95  underlie the valleys or bases  92  of the infrared source  88 ; between the corrugated panel ridges  95  and the infrared source valleys or bases  92  are located corresponding ones of the opposing radiation bars  79  of heaters  72  ands  74  for that source. Heater bars  79  directly heat corresponding infrared source or emitter valleys or bases  92  for effective heat transfer.  
         [0068]    It will be appreciated that the infrared source or emitter  88  incorporates a shield to protect the sauna user from the high temperatures, on the order of 200 degrees or more Fahrenheit, of its valleys or bases  92 ; its closely spaced fins  90  even blocking finger user contact with the heated bases  92 , and themselves having on free ends only maximum temperatures of 140 degrees.  
         [0069]    While the infrared source or emitter  88  acts as a shield to protect the sauna user from the high temperatures of its valleys or bases  92 , it also acts as a shield to protect the sauna user from the still higher temperatures of the electric infrared heaters  72  and  74 .  
         [0070]    It should be understood that not all of the radiation of the electric infrared heaters  72  and  74  is absorbed by the infrared source or emitter  88 ; some of the heater radiation passes through the valleys or bases  92  to directly heat the sauna user too.  
         [0071]    Maintenance of the sauna is effected by simply wiping the finned infrared source  88  with a light cloth.  
         [0072]    Actually, passage of the radiation from the heaters  72  and  74  to the sauna user may be facilitated by providing openings in the emitter valleys or bases  92  to allow its direct passage to the user rather than being intercepted by the valleys or bases. Then the infrared source or emitter  88  functions less as a radiation emitter and more as a shield.  
         [0073]    Alternatively, the infrared source or emitter  88  may be almost totally converted to the shield function by mounting the fins  90  on a lattice work which minimally interrupts the flow of infrared radiation from the heaters  72  and  74  while allowing retention of the shield function of the fins.  
         [0074]    While the emitter and/or shield  88  has been shown as embodying fins  90 , it will be understood that other protrusions such as columns, pyramids or conical sections may extend upwards from the valleys or bases  92  or lattices; their spacing from each other being such as to prevent user contact with the hot bases or infrared heaters there behind, and to present comfortable-to-the-touch ends when the sauna is in use.  
         [0075]    A strong physical cover  96  may be employed to protect the infrared source or emitter  58  on the cabinet back or rear wall  18  from the weight of a user leaning there against. The cover  96  may also be shaped to constitute a suitable and comfortable seat back for the user.  
         [0076]    The sauna adjustable seat structure generally indicated by the numeral  98  in FIGS. 6 and 9 is supported more on the back wall  18  of the sauna, than that of FIG. 1 with the adjustable floor post  28 . The seat structure  98  includes a top flat rectangular panel  100  and two supporting triangular side panels  102 . The rear generally vertical edges of the panels  102  fixedly mount upper and lower headed pins  104  and  106  which are slidably received in upper and lower slots  108  and  110  formed in L-shaped brackets  112  suitably fixed to the cabinet rear wall  18 . Rearwardly and downwardly extending side slots  114  off the lower slots  110  enable adjustment of the seat panel  100  to different heights to suit the build of the user.  
         [0077]    Side panels  116  extending from the lower back of the cabinet and interconnected by brace  118 , may be employed to mount a roller  120  to render the sauna very portable. The side panels  116  may also form part of a box to hold additional equipment for the sauna.  
         [0078]    The electrical connections for the sauna are shown schematically in FIG. 10. The electronics box  122  would be located under the seat to be out of the way of the user. An outlet cord, represented by power lines L 1  and L 2 , would extend out of the box  122  and out of the sauna cabinet  10  for connection to any suitable source of AC  110  current, usually a home wall outlet. The lines L 1  and L 2  would be extended from the box  122  to a double pole On/Off switch  124  mounted on the cabinet door  24 . From there, they would extend to a Temperature/Time Controller  126  through a Timer Circuit  128  to a Temperature Control Circuit  130  receiving controlling input through suitable wiring from a temperature sensor  132  mounted on a wall of the cabinet. Assuming that time guide provided by the timer circuit  128  is not exceeded and the temperature sensed by the sensor  132  is in the permissible range, the control circuit  130  will pass current to the door heaters  40 - 48  through power wires  134 , and to the cabinet heaters  50 - 58  through power wires  136 . The wires  134  and  136  will be connected to the individual ones of the dual heaters as shown in FIG. 2: the corresponding connectors at each end of the dual heaters being oppositely connected to the power lines L 1  and L 2 . Thus as shown in FIG. 2, connector  78  of the top heater  72  will be connected to line L 1  of lines  134  and connector  84  of the bottom heater  74  will be connected to line L 2  of lines  134 ; whereas connector  78  of the top heater  72  will be connected to line L 1  of lines  134  and connector  86  of the bottom heater  74  will be connected to line L 1  of lines  134 . Thus current will be flowing in opposite directions at any point in time in every pair of corresponding bars in the two heaters, to cancel essentially all AC current-induced ELF EMFs.  
         [0079]    In order to reduce if not eliminate ELF EMF due to the heater power lines such as  134  and  136 , a round solid wire  138  may be mounted inside a tubular solid wire  140  but separated therefrom by an insulating material  142 , as shown in FIG. 11. In FIG. 12, hollow wire  144  is mounted inside a thinner-walled tubular wire  146  to place the centers of current conductance closer to each other and hence more effective in EMF cancellation. Equal masses obtain in each of the wires of FIG. 11, and in each of the wires of FIG. 12, to accommodate equal current flow. The wires are separated from each other by an insulating material  148 . FIG. 13 shows the significant reduction of measured EMF strength that obtains from the use of a wire within a wire instead of regular side-by-side power wiring. For a regular power wire, a high extremely-low-frequency EMF of 25 milligauss may obtain within one inch of it, and of about 16 milligauss at 3 inches. For the power wiring of this invention, approximately only 1 milligauss obtains at even a nearness of 1 inch distance.  
         [0080]    [0080]FIG. 14 shows still lower ELF EMF power wiring constituted of two juxtaposed solid flat wires  150  and  152  separated by a suitable plastic insulator also used to encapsulate the wires for safety. Equal masses obtain in the case of the wires  150  and  152 , too.  
         [0081]    An advantage of the invention, particularly in commercial applications, is that the sauna can be easily kept clean. The cabinet  12  including its door  24 , seat structures  26  or  98 , and infrared sources or emitters  88 , are all made of impervious plastic, facilitating cleaning especially compared to wood-constructed saunas. The plastics chosen have low outgassing (the emission of plastic molecules into the air accompanied by an odor).  
         [0082]    It will be appreciated that the finned infrared emitter and the dual infrared heater, singly and in combined assembly, may also be safely used in other close-range personal heating situations; e.g. at or under office desks and work stations; in domestic and institutional shower stalls; and near cribs, in hospital incubator rooms, and near bassinets for washing babies, etc., upon reducing the distance between the fins  90  of the emitter  88 .  
         [0083]    It will also be appreciated that the low ELF EMF feature of the dual heater of the invention allows the dual heater to be advantageously also used in floor, ceiling, and wall radiant-room heating systems; in bed, water bed, sofa, and massage table heating systems; and in car seat, boat seat, stadium seat, and submarine and ship barrack personnel heating systems.  
         [0084]    While there has been shown and described preferred embodiments of the invention, it will be apparent to those skilled in the art that other and different applications may be made of the principles of the invention. It is desired therefore to be limited only by the scope or spirit of the appended claims.