Abstract:
A self-contained evaporative personal cooling device fits conformally around a user&#39;s neck or other body portion. The device includes at least one heat dissipating member that is urged conformably against the body portion to absorb heat therefrom. The device-facing side of this member preferably has a large surface area with a liquid-wickable surface. A liquid-retainable material contacts at least a portion of the wickable surface area and also defines at least one air plenum. Ambient air is moved along the plenum, preferably by a battery-powered fan. The air transfers heat from the member, cooling the user, and is exhausted from the device. A thermostat can sense temperature at the heat dissipating member to control duty cycle of the fan to prevent overcooling the user.

Description:
RELATIONSHIP TO OTHER APPLICATION 
     This is a continuation-in-part of application Ser. No. 08/924,580 filed Sep. 5, 1997, now U.S. Pat. No. 5,802,865 issued Sep. 8, 1998. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to personal cooling devices, and more particularly to evaporative coolers that are worn around the neck or head of a user. 
     BACKGROUND OF THE INVENTION 
     Individuals often wish to be cooled, especially in warm ambient temperatures. The desire to be cooled may arise indoors or out, while exercising, engaging in sports, driving, or being in an environment that is not comfortably cool. 
     It is known in the art to provide a cap to be worn by an individual that can provide some cooling. U.S. Pat. No. 5,365,607 to Benevento, for example, discloses a cap whose headband includes a plurality of tapered porous pads. The pads are wet with water and apparently produce a cooling effect to the user&#39;s head as the water evaporates. 
     U.S. Pat. No. 3,029,438 to Henschel discloses a water-cooled cap in which an inner aluminum strip contacts the wearer&#39;s head, and is contacted with a water absorbent sponge strip (or strips), in turn over-covered by a fabric. The sponge material is wet, and as the water evaporates, the aluminum strip cools, thus cooling the wear&#39;s head. 
     U.S. Pat. No. 4,130,902 to Mackenroth discloses a cooling hat band that includes an outer support band, an inner absorbent band, a wicking element and a water reservoir. Reservoir water moves along the wicking element to the absorbent band, whence it evaporates, passing through holes in the support band. The evaporative effect is said to remove heat from the headband, and thus from the wear&#39;s forehead. 
     However, not all individuals like to wear caps, and participation in some sports, e.g. bicycling, may dictate that another type of headgear be worn, a helmet for example. Thus, several attempts have been made in the prior art to improve upon a basic cooling band, such as a tennis player might wear around the forehead. For example, U.S. Pat. No. 4,742,581 to Rosenthal discloses a laminated cooling band comprising a skin-contacting air pervious heat conductive layer edge-connected to an air pervious fabric that is moistened with water exposed to ambient air. This device is said to cool the wearer as water evaporates from the outer fabric. However, as is typical with many prior art devices, evaporative cooling is dependent upon ambient air motion. If the wearer is stationary, the efficiency of evaporative cooling decreases. 
     Notwithstanding the above devices, there is a need for a self-contained personal evaporative cooling device that promotes efficient cooling. If worn about the user&#39;s neck, such device should not require headgear. Further, such device should be useable on other portions of the user&#39;s body, the forehead, for example. Preferably such device should enhance evaporative cooling by maximizing the heat sinking area, maintaining a thin film of liquid upon such area, and by circulating air within the device. Such device should be simple to use and wear, and should provide cooling that lasts for several hours without replenishment of liquid or energizing source. The present invention provides such a cooling device. 
     SUMMARY OF THE PRESENT INVENTION 
     A preferred embodiment of the present invention is a self-contained evaporative personal cooling device in the form of a C-shaped band that fits conformally around a portion of a user&#39;s body, e.g., the neck or forehead. The device includes an articulated housing within which is disposed a heat sinking or dissipating member, preferably implemented as a plurality of side-edge-joined metal plates that each have a first, neck-facing surface, and a second, opposite, surface. The metal plates are urged conformably against the user&#39;s neck or forehead such that the first, or exterior plate, surfaces contact the neck. A water-retaining preferably foam-like sponge material is disposed within the housing in contact with the upper and/or lower surfaces or regions of the metal plates but spaced-apart from the second surface of the plate body to form a plenum therebetween. The sponge material is saturated with a liquid, preferably water, introduced through liquid intake slots in the housing, before the cooling device is to be used. The device includes a DC powered fan that draws air into the housing though air intake vents and then circulates the air within the plenum defined between the metal plates and the sponge material and out through air exit vent openings in the housing. Moisture from the sponge material wets the plenum-facing surface of the metal plates, and the fan-circulated air produces evaporation. The evaporation cools the metal plates, which absorb heat from the user&#39;s neck or forehead and thus cools the user. 
     Preferably the plenum-facing surfaces of the metal plates define pins, ridges, fins, or the like to increase plate surface area. To help promote the cooling process, a wicking material is used to coat at least portions of the ridged contact surface area. During device manufacture a surfactant is applied to the sponge material and to the preferably wicked surface areas of the metal plates to encourage capillary-like liquid migration and promote cooling efficiency. In use, a wicking action encourages water migration from the sponge material to the ridge surfaces of the metal plates. Preferably the plenum-facing surface of the sponge material is covered with a moisture barrier. However the moisture barrier does not cover regions where the sponge material contacts the metal plates or where the sponge material is adjacent housing slits through which water is introduced. The barrier helps maximize evaporation at the metal plates by preventing circulation of dry plenum air from evaporating water from the foam. Further, the barrier reduces water loss and water leakage. If desired, a color-changing material may be included to serve as a low water indicator. To promote efficiency, the fan blade preferably includes a centermost axial portion that draws air into the housing through input vents, and an outermost radial portion that circulates the air in the plenum within the housing. Alternatively the fan might be replaced with other air-moving means including electro-kinetic mechanisms that move air silently and without moving parts. 
     An alternative preferred embodiment provides a reverse air flow such that ambient air is drawn into the device at one or more generally forward or peripherally facing regions of the device, and warmed air is exhausted at a generally rear facing region of the device and/or along peripheral edges of the device. The ambient air may be drawn-in and exhausted actively by a motor, or may be drawn-in and exhausted passively, by relative forward motion of the device in the ambient air, e.g., when worn by a jogger, a bicyclist, etc. 
     In these and/or other embodiments, the preferably foam-like sponge liquid-retaining material need only contact the heat dissipating member at one location, for example in a central portion of the device-facing surface of the dissipating member. Indeed, the device-facing surface of the heat dissipating member may itself be a porous metal-type material, affixed or integral with the body portion-facing surface of the dissipating member, such the foam-like material can be eliminated. In such embodiment, one or more micro-plenums may be defined within the porous region of the dissipating member. In yet another embodiment, the heat dissipating member is made from a fabric such as felt cloth. 
     If desired, one or more pumps may be provided to spray a mist of water onto the device-facing surface of the heat dissipating member, and/or into fan-moved air in the plenum(s). 
     Other features and advantages of the invention will appear from the following description in which the preferred embodiments have been set forth in detail, in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the present invention worn around the neck of a user; 
     FIG. 2 is a cross-sectional view along the center of the present invention; 
     FIG. 3 is a perspective partial cutaway view depicting the plenum-facing side of the dissipator plates and sponge material and the resultant plenum, according to the present invention; 
     FIG. 4 is a perspective view of a motor and a preferred fan blade assembly, according to the present invention; 
     FIG. 5A is a perspective view of an alternative embodiment in which air flow is opposite from that in the embodiments of FIGS. 104, according to the present invention; 
     FIG. 5B is a perspective view similar to FIG. 5A, but in which an axial fan blade assembly is used, according to the present invention; 
     FIG. 6A is a cutaway view depicting multiple plenums in an alternative embodiment of the present invention; 
     FIG. 6B is a cutaway view depicting use of reservoir and wick combinations in an alternative embodiment of the present invention; 
     FIG. 6C is a cutaway view depicting use of pumps in an alternative embodiment of the present invention; 
     FIG. 6D is a cutaway view depicting use of wickable bead-like structures to enhance the device-facing area of the heat dissipating member, according to the present invention; 
     FIG. 6E is a cutaway view depicting use of wickable bead-like structures to enhance the device-facing area of the heat dissipating member, according to the present invention; 
     FIG. 6F is a cutaway view depicting use of porous device-facing area of the heat resulting from micro-grooving, micro-channelling, or use of wickable members, according to the present invention; 
     FIG. 6G depicts use of a cloth heat dissipating member in an alternative embodiment of the present invention; 
     FIG. 6H depicts use of pumps and reservoirs and a fan unit to move water mist through the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 depicts an evaporative neck cooler  10  worn around the neck of a user, the user shown drawn in phantom lines. Alternatively, a cooler  10 ′ may be worn in headband fashion around the forehead of a user, as shown in phantom. Hereinafter neck cooler  10  will be described, however it is to be understood that the description is also applicable to a forehead cooler  10 ′. 
     Cooler  10  includes a generally “C”-shaped housing  20  that preferably encircles at least 180° and includes an opening  30  sized to permit housing  20  to pass around the neck  40  of a user. In the preferred embodiment, housing  20  is formed of a plastic material and comprises a central housing portion  50 -A and end portions  50 -B, the portions being joined together by flexible linkages  60 , that may be accordion or bellows-like in function. Collectively, portions  50 -A and  50 -B are biased by linkages  60 , and/or by the material comprising housing  20  to urge cooler  10  to fit snugly but comfortably around the user&#39;s neck. Of course housing  20  should be sufficiently flexible and/or articulatable to permit easy removal of device  10  from a user&#39;s neck. Those skilled in the art will appreciate that more or fewer than two linkages  60  could be employed, and that if a suitably elastic housing material were used, possibly no linkages would be required. Preferably distal ends  70  of housing portions  50 -B are rounded to promote user comfort in wearing cooler  10 . (Obviously, a forehead cooler  10 ′ will be sized to fit comfortably about the forehead of a user.) 
     Preferably central housing portion  50 -A includes a motor housing  80  having air intake vents  90 , and a small DC motor  100  retained within a retainer cup  102  within housing  80 . A battery  110  (e.g., a 1.5 VDC AA unit) is retained within a battery compartment  120  that may be formed on an adjacent region of housing  20 . A user-accessible ON/OFF switch  130  enables the user to activate motor  100  by switcheably connecting/disconnecting battery  110  from the motor. (As shown in FIG. 2, when activated, motor  100  rotates a fan blade assembly  200 .) Of course DC motor  100  may be powered by other than a battery. For example, solar cells might be disposed on the exterior surface of device  10  to generate motor operating potential. Alternatively, motor  100  might be a mechanical, wind-up type motor that requires no electrical operating potential. 
     Referring again to FIG. 1, preferably housing portions  50 -A,  50 -B include liquid intake or input slot openings  140  in their exterior surface, e.g., the housing surface that does not face toward the user&#39;s neck. Of course more or fewer slots can be provided than the number shown, and the shape of some or all of the slots may differ from what is depicted in FIG.  1 . Preferably the upper and lower surfaces of the housing portions also include a plurality of air exit vent openings  150 , to promote cooling. It is understood that the shape, number and location of vent openings  150  may differ from what is shown in FIG.  1 . For example, substantially more such openings may be provided. 
     As best seen in FIGS. 1 and 2, cooler  10  further includes water (or liquid) retaining or absorbing material, preferably foam-like porous sponge material  160 , that is disposed within housing  20  adjacent the inner wall of the housing exterior surface. When device  10  is used material  160  is saturated with liquid, preferably water, introduced via slots  140 . Preferably material  160  is ordinary cellulose sponge, a material that can absorb water to saturation, and then retain the water without undue expulsion, e.g., by leaking out of housing  20  onto the user. Of course other materials with similar water retaining characteristics may be used for material  160 . Experiments by applicant with open cell high density polyethylene foam including HDPE and PVA sponge indicate that while such material adequately retains water, water migration through the material is slower than if cellulose sponge material were used. However, material  160  need not necessarily be foam-like or spongy, and could instead be a fabric, or a non-woven material. 
     Cooler  10  also includes a heat dissipating member  170  that preferably is metal. Heat dissipating member  170  is retained by holder  20  such that the first dissipator surface  172  is urged against the neck of the user (see FIG.  2 ). Surface  172  draws body heat from the user&#39;s neck into the dissipator member  170 . In the embodiment of FIG. 1, there is a single heat dissipating member  170  for each housing portion. However, a plurality of smaller heat dissipating members  170  may be provided in each housing portion as shown in FIG. 2, especially if the housing portions are sufficiently flexible. 
     As will be described, water-saturated sponge material  160  within housing  20  wets plenum-facing second surface  174  of member  170 . An evaporation is promoted that lowers the temperature of surface  172 , thus cooling the user&#39;s neck. 
     In the embodiments of FIGS. 2 and 3, the dissipating member comprises a plurality of aluminum plates or elements  170 , joined vertical edge-to-vertical edge by mechanisms  176 . Mechanisms  176  preferably are biased hinges that urge plates  170  to flexibly conform to the surface of the user&#39;s neck. Although mechanisms  176  are depicted in FIG. 3 as being hinge-like, other mechanisms that retain adjacent plates  170  while urging the plates to generally conform to the shape of a user&#39;s neck may be used instead. For example, mechanisms  176  could include hinges (including plastic flexible tape as hinges) that include a torsion spring to create a bias force. Mechanisms  176  might include a band of metal that creates a bias force, using either a separate band between adjacent plates  170 , or one band to connect and bias many or indeed all of the plates  170 . 
     Thus, it will be appreciated that heat dissipator member  170  might itself comprise a continuous band of flexible conductive material, or a separate such band for each housing portion (e.g., as shown in FIG.  1 ), rather than the plurality of plates depicted in FIG.  2 . In such an implementation, there might be no need for separate bias or joining mechanisms  176 . Regardless of the implementation, material  170  should be a good dissipator of heat, preferably be lightweight, and should be biased to conform generally and flexibly to the user&#39;s neck. 
     As best seen in FIGS. 2 and 3, portions of sponge material  160  preferably contact the upper and/or lower regions  178  of dissipator plates  170 . However, exterior plate surface  174  is spaced-apart from material  160  such that plenums  180  are defined within housing  20 . As will be described, fan  100  and fan blade assembly  200  move ambient air into housing  20  and along plenums  180  to promote evaporative cooling of the user&#39;s neck. FIG. 2 is intended to show the relative relationship of the components comprising device  10 , and is not drawn strictly to scale. In practice plenums  180  may be larger than what is shown to promote more efficient cooling. 
     As noted, sponge material  160  is preferably saturated with water. To minimize loss of water through evaporation (other than at region(s)  178  of the dissipator plates), the outer surface or skin of material  160  preferably is coated or covered with a thin moisture barrier, a plastic film, for example. However, as shown in FIG. 3, at the interface  162  of the sponge material and dissipator plates regions  162  the barrier is not formed, (or if formed is removed) to promote water cooling of dissipator plates  170 . Preferably such moisture barrier on material  160  is not formed (or removed if formed) adjacent slits  140  in housing  20 , to facilitate loading the sponge material with water. The moisture barrier not only prevents air circulating in plenums  180  from evaporating water from the sponge material, but also reduces leakage of water onto the user&#39;s neck or clothing. Moisture loss may also be reduced by providing slots  140  with covers that are removed or hinged out of the way when adding water to cooler  10 , but are otherwise closed. Note the presence of openings  150 ′, which coincide in location with openings  150  in the upper and lower housing surfaces. Openings  150 ′ may be larger than openings  150  but should not be smaller, to avoid impeding the air flow exiting the device housing. 
     The preferably somewhat flexible nature of housing  20  and material  60  is such that the dissipator plates  170  are urged towards the user&#39;s neck to make reasonably good thermal contact therewith. Heat from the user&#39;s neck is transferred at least in part to surface  172  of plates  170 , which plates are cooled by the presence of water within sponge material  160 . 
     To promote water-cooling of plates  170 , a water wicking action is encouraged along plenum-facing surface  174  of dissipator plates  170 . As seen in FIGS. 2 and 3, surface  174  preferably includes fins, projecting pins or rectangles or squares, or the like to increase surface area. It is understood that the configuration shown in FIGS. 2 and 3 is only exemplary, and that the drawings are not precisely scaled. In practice, a surface  174  having projecting pins rather than fins appears to promote more efficient heat transfer and cooling. In such an embodiment, heat transfer efficiency is promoted by forming dissipator plates  170  with many relatively thin, preferably pin-shaped, projections on plenum-facing side  174 . 
     To promote migration of water from the sponge material into surface  174 , a wicking material  179  is provided. Wicking material  179  preferably comprises silicon carbide powder, about 100 mesh, although 80 mesh aluminum powder may be used, among other wicking materials. A thin layer of glue is applied at least to regions of surface  174  of plates  170 , and the wicking powder is dusted onto the glued regions. Applicant used commercially available Gorilla brand premium glue although other adhesives could be used. The plate with glued powder is then dried, e.g., for about 30 minutes at about 300° F. Alternatively, the heat dissipator plates could be flocked with a short fiber material, although applicant has experienced some inconsistency in temperature drops using various flocked coatings. As yet another alternative, surface  174  might be acid-etched or sandblasted to define a wicking surface, without using mesh powders and adhesives, or flocking material. 
     To further promote wicking and resultant cooling efficiency, a surfactant, e.g., household liquid dishwashing detergent, is applied to the wicking-coated surfaces of plates  170  during device manufacture. Preferably, sponge material  160  is soaked with the same surfactant during manufacture as well. It is anticipated that users will on occasion re-apply surfactant to the metal plates and sponge material, when cooling efficiency appears to have degraded. 
     In using device  10 , material  160  is saturated with water via openings  140 . The evaporative neck cooler is then put around the user&#39;s neck (or forehead) and switch  130  turned ON. As battery  110  energizes motor  100 , fan blade  200  rotates. As seen in FIG. 4, fan blade  200  preferably includes a radially configured outer blade portion  210 , and an inner axially configured blade portion  220 . Inner blade portion  220  is formed on a hub  230 , and a second hub  240  is common to blade portions  210  and  220 . Alternatively, fan blade  200  may comprise only axially disposed blades, or only radially disposed blades set at an angle that forces a portion of the air toward the underlying heat dissipator surface and a portion of the air outward toward the end sections of the housing. In any event, second hub  240  preferably includes openings  245  to permit air passage therethrough. Alternatively, second hub  240  may be fabricated as a pair of spaced-apart hoops that are spanned and joined by fins  210  on the exterior surface. 
     In FIG. 4, the direction of air flow is left-to-right, as shown by the parallel arrows on the left, and the rotational direction is as shown by the curved arrow ω. The inner axial blades  220  draw ambient air through fan housing vents  90  (see FIG. 1) into housing  20 , and the radial outer blades  210  then move or circulate this air along plenums  180 . This circulated air then evaporatively cools water-moistened surface  174  of plates  170 . Surface  174  will have been wetted by water from sponge material  160  that, due to the absence of a moisture barrier at interface regions  162  (see FIG. 3) can move onto surface  174 , promoted by wicking material  179 . The air exits the plenum via openings  150 ′ in the sponge material, and corresponding openings  150  in the upper and lower housing surfaces. 
     One may first treat the sponge material with an anti-bacterial anti-fungal solution. Such a solution can inhibit growth of undesired microorganisms within the cooler, promoting hygienic use of the cooler. 
     Understandably it is important that water be retained within sponge material  160  for efficient cooling to occur. Optionally, neck cooler  10  can be provided with a visual indicator  250  (see FIG. 1) to provide visual indication when material  160  is becoming dry. For example, material  250  may be a strip of thin water permeable material, cloth for example, impregnated with cobaltous chloride. This chemical will cause strip  250  to appear pink when wet, but blue when dry. 
     The present invention will provide effective cooling as long as metal plate surfaces  174  remain moist, and as long as fan  100  circulates air into and within housing  20 . In practice, plate surfaces  174  can remain moist for 3 hours or more, and a typical AA battery  110  can power  100  for about 14 hours. Temperature reductions from ambient air temperature of up to about 20° F. are obtained at about 100° F. ambient and about 20% relative humidity. Even greater temperature reductions can be attained at increasing ambient temperature and/or decreasing relative humidity. These cooling reductions are attained without requiring a user to handhold a cooling device, and without exposing the user to water dripping onto the neck or clothing. While being thus cooled, the user can freely participate in all manner of indoor or outdoor activities including without limitation walking, jogging, bicycle riding, exercising, working, and motor vehicle operating. 
     While the present invention has been described with respect to a cooling device for a human, e.g., for use on the neck, forehead, or other body part, it will be understood that other animals may also benefit from the device. For example, a suitably sized device might be worn by pets. A guide dog for a blind person might especially benefit from a neck evaporator device on a hot day when excessive heat might otherwise impair the dog&#39;s ability to protect its owner. 
     It will also be appreciated that while the preferred embodiment has been described with respect to a self-retaining device, e.g., a “C”-shaped device that supports itself, the present invention could be fabricated as a flat device that is strapped or otherwise supported against a surface to be cooled. For example, a flat-shaped device according to the present invention could be strapped to a user&#39;s chest, back or other body region to promote cooling for comfort or perhaps for medical purposes. 
     Turning now to FIG. 5A, a new embodiment is shown in which air flow is opposite from that associated with the embodiments of FIGS. 1-4. In FIG. 5A, one or more intake ports  175  are formed in a forward-facing region of device  20 ′. By forward-facing, it is meant that when device  20 ′ is worn by a user, ports  175  will face generally forward. Note in FIG. 5A that motor  100  and fan assembly  200  are shown in phantom and reversed relative to the configuration of FIG.  4 . Thus, motor  100  may be mounted closer to the front-facing region of device  20 , with fan blade assembly  200  closer to the rear-facing region of device  20  if desired. In the configuration of FIG. 5A, air flow (denoted “IN”) enters device  20 ′ through intake ports  175 , flows through plenums  180  and exits (denoted “OUT”) via exit ports  103  (as well as through any other exit ports present). If air flow is active, then motor  100  and fan assembly  200  will be present, and will be configured to draw air into and through device  20 ′, as shown by the hollow arrows. 
     On the other hand, the configuration of FIG. 5A can omit motor  100  and fan assembly  200 . In the resultant configuration air passively enters ports  175 , passively moves through device  20 ′ (e.g., via plenums  180 ) and passively exits via ports  103  (and any other exit ports present) . This passive movement results from relative motion of device  20 ′ in ambient air. Thus, if device  20 ′ is worn by a jogger, a bicyclist, etc., as the use moves forward, there will exist relative motion of ambient air relative to device  20 ′, almost in ram-jet function. Although passive operation may be less effective than active operation where a motor and fan assembly is used, the resultant device will be lighter in weight, can be manufactured somewhat more compactly, and will be less expensive to produce. 
     FIG. 5A also depicts the optional inclusion of a motor speed control device  132 , preferably electrically coupled between the windings of motor  100 , switch  130  and power supply  110 . Control device  132  may be used with any of the embodiments described herein, and preferably includes a two-pole (or more) thermostat. In practice, the present invention can actually function too well, that is, over-cool a user. Rather than require the user to manually activate switch  130  or even remove the invention, a thermostat or thermistor  132  can automatically help regulate the present invention. 
     Unit  132  senses temperature adjacent heat dissipator  170 , and when this temperature falls below a predetermined threshold (perhaps in a range of about 60° F. to 70° F.) thermostat or other device  132  can open-circuit electrically. When device  132 , which may be a simple bi-metal unit, open-circuits, operating power to motor  110  will be interrupted, which will stop the active (e.g., fan-moved) movement of air within the device plenum(s). When the monitored temperature at the heat dissipating member rises above the predetermined threshold, unit  132  will close, permitting motor  110  to become active, thus cooling the user. If desired, unit  132  could also provide a time-interrupt function such that once unit  132  opens, it will remain open for at least a given amount of time, e.g., perhaps 10 minutes. If desired, a usere-variable thermostat control can be provided, whereupon the threshold temperature may be user-selected. 
     If desired, unit  132  could include a thermostat and associated circuitry to regulate duty cycle of operating potential to motor  100 . Thus, under normal operating conditions duty cycle may be close to 100%, as an “almost too cold” temperature is sensed, unit  132  can decrease duty cycle of voltage provided by battery  110  to cause fan assembly  200  to rotate more slowly. As temperature sensed at heat dissipator  170  begins to rise, unit  132  will cause motor rotational speed to increase, to maintain an acceptably cool, but not too cold, temperature where the heat dissipator member contacts the user&#39;s body. 
     FIG. 5B depicts an embodiment similar to FIG. 5A, except that an axial fan blade assembly is used rather than a radial fan blade assembly, as shown in FIG.  5 A. In general, a radial fan blade assembly (e.g., FIGS.  2  and  5 A), in which the exhausted air comes from the side of the assembly, seems to be more efficient than an axial blade configuration in moving air under pressure for a given amount of electrical power. In FIG. 5A for ease of illustration exhaust vents are shown at the rear portion of the device. Understandably, efficiency may be promoted by disposing exhaust vents even closer to the fan assembly exhaust stream on the sides of the device. 
     In any of the embodiments of the present invention described herein, it is understood that a variety of fan blade assemblies may be used. FIG. 5B also depicts optional retaining belt portions  177 A,  177 B that engage each other at belt regions  179  to help secure the present invention to a user&#39;s body. 
     It will be appreciated from all of the foregoing that the present invention absorbs heat from the user&#39;s body via heat dissipating member  170 , and provides liquid to the device-facing surface  174  of that member. An evaporation process from surface  174  occurs, which process is encouraged by the air flow (active or passive) through plenum(s)  180 . The air flow takes on the moisture, which helps pull heat from dissipating member  170 , which cools the user&#39;s body portion in contact with body-facing surface  172  of element  170 . 
     The same process occurs in the embodiment of FIG. 6A, wherein liquid retainable material  160  contacts heat dissipating member  170  at at least one location rather than at at least two locations, as in the embodiment of FIG.  3 . Indeed, in FIG. 6A, contact is made along the device-facing surface  174  rather than at the edges. As a result, two plenums  180  are formed. Material  160  may be the same sponge-like material as described earlier herein, although other materials may instead be used. In the embodiment of FIG. 6A (as in any of the other embodiments), heat dissipator element  170  may be a single continuous band of material rather than a series of linked shorter length material pieces. Of course, element  170  may be a series of linked shorter length material pieces. Preferably the regions of surface  174  subjected to moisture from material  160  will have been enlarged in area, using any of the methods or materials (or equivalents thereof) described herein. As practiced herein, the area of enlargement may be macroscopic or larger, or microscopic in magnitude. It will be appreciated that a device housing is not depicted in FIG.  6 A. 
     In the embodiment of FIG. 6B, one or more reservoirs  182  contains a liquid  184  that is communicated through one or more wicks  186  to surface  174  of heat dissipating element  170 . Wick  186  is made from a material that will conduct the liquid, cotton for example, although numerous other materials may instead be used. In practice, liquid  184  will be water but any high volatility, rapidly-evaporating liquid may be used. Alcohol, for example, would work better than water as liquid  184 , but the exhaust fumes would likely intoxicate a wearer of the present invention. Where multiple reservoirs  182  are employed, they may be disposed at various locations along the length of heat dissipator element  170 . Preferably there will be fluid communication between the reservoirs such that a single liquid intake port can be used to fill more than one reservoir with additional liquid  184 . 
     The embodiment of FIG. 6C augments what was shown in FIG. 6B by replacing wick  186  with a hollow tube  185  through which liquid  184  is drawn by a pump  187 , energized by battery  110 . Pump  187  preferably comprises two rotatable cogged gears  191 A,  191 B that are exposed to liquid  184  and create a mist-like spray  189 . Essentially the liquid travels on the outer surface of the gears, and is expelled on an outlet side of the pump. Pump  187  directs the spray, e.g., through nozzles or the like, toward surface  174  of heat dissipator element  170 . This carburetor-like spray could result in reduction or elimination of sponge-like material  160 . However efficiency could suffer as the spray would moisten the preferably dry air within plenum(s)  180  that is desired to evaporatively remove heat from the heat dissipating member  170  and ultimately out of the present invention. 
     In the embodiments of FIGS. 6B and 6C, the absence (or at least curtailed size) of foam-like material  160  provides more volume within the device housing to store liquid  184 . This in turn can allow the present invention to operate longer before replenishing the liquid supply. It will be appreciated that FIGS. 6B and 6C do not depict a housing for the device for ease of illustration 
     It is understood that in any embodiment, device-facing surface  174  of the heat dissipating member preferably will be enlarged in effective surface area. As noted, an enlarged effective surface area promotes better transfer of heat from heat dissipator  170 . Area enlargement may be accomplished using any of the techniques or methods described herein, or equivalents thereof. 
     FIG. 6D shows an embodiment in which surface  174  of the heat dissipator includes bead-like particles  176  that collectively increase the effective area of surface  174 . Particles  174  preferably are small in individual area and have a liquid wickable surface. Without limitation, particles  174  may be silicon carbide beads or powdered silicon carbide. Other materials may instead be used, the desired qualities being a liquid wickable characteristic, small individual size giving rise collectively to greater effective combined surface area, and ability to adhere to surface  174  of heat exchange element  170 . 
     As an alternative to physical bead-like particles  176 , a similar effect can be obtained by micro-grooving surface  174  to form channels, e.g., by machining, by sand blasting, by chemical treatment including etching, among other techniques known to those skilled in the art. 
     A device housing  50  is depicted in FIG. 6D as attaching to peripheral regions of surface  174  of the heat dissipator element  170 . Such housing attachment is in contrast to the embodiments of FIGS. 1-3 and  5 A and  5 B in which the housing surrounded and retained peripheral regions of the user-facing surface  172  of the heat dissipator member. 
     Although for ease of illustration housing  50  is drawn as being somewhat semi-rectangular in cross-section, in practice housing  50  will likely have a more streamlined cross-section, e.g., a section of an ellipsoid. Further, it will be appreciated that the material comprising housing  50  preferably is lightweight and may itself be flexible, especially if housing  50  is a single flexible member rather than an assemblage of articulatable or hinged-together members. In some embodiments, housing  50  may not encompass a sufficient angular arc to be self-attaching to the user&#39;s body or may lack rigidity to be self-attaching. In such embodiments, one may attach a small length of belt or the like to one or both distal ends  70  of the device housing. Such a belt is shown in FIG. 5B in which distal ends  175  of the device housing are secured to belt portions  177 A,  177 B. The free end(s) of the belt portion(s) attach to one another at portion  179  using a length-adjustable attachment mechanism, e.g., via Velcro™-type material mating surfaces, a belt locking mechanism (not shown) or the like. Of course a single longer piece of belt could be used (e.g., portion  177 A), the free end of this belt adjustably attaching to the other distal end of the device housing using any of a variety of attachment mechanisms. Of course, if desired, the present invention could be manufactured to encompass substantially a 360° circumference about the user&#39;s neck or other body portion. In such instance, a latch-type mechanism could attach distal ends  70  of the device to each other. 
     In the embodiment of FIG. 6E (which does not depict the housing for ease of illustration), device-facing surface  174  of the heat dissipating member now includes a thicker region of beads  176  (or the like), and liquid retaining foam or other material  160  now contacts more of surface  174 . Note that a plurality of micro-plenums or channels  180  is defined in the thicker region of beads  176 . If desired, when attaching bead-like wickable elements  176  to surface  174 , rod or channel members may be left in place to define through-plenums, and removed (or lost due to melting) preceding or following the attachment process. These multiple plenums and/or micro-plenums permit fabricating the present invention with a shallower housing configuration, front-to-back. Stated differently, a cross-section of the embodiment of FIG. 6E can be shallower than a cross-section of the embodiment of FIG. 6A or of FIG. 1 or  2 , etc. 
     In the embodiment of FIG. 6F, the device-facing surface  174  of the heat dissipating element has been made extremely porous due to the presence of micro-grooving or micro-channelling, resulting from wickable members  176 . Indeed, so many micro-plenums  180  are formed that, but for its stiffness, device-facing surface  174  now acts somewhat sponge-like, and indeed material  160  may be omitted. In this embodiment, as in the embodiments of FIGS. 6A and 6E, liquid may be introduced onto surface  174  using wicking (as shown in FIG.  6 B), or actively mist-spraying (as shown in FIG. 6C) or by saturating surface  174  with liquid (as in the embodiments of FIGS.  1 - 3 ), as though surface  174  were sponge-like material  160 . 
     The embodiment of FIG. 6G recognizes that a sufficiently micro-grooved or porous heat dissipating element  170  can, if sufficient micro-plenums are formed, take on the characteristics of a fabric material, cotton or felt for example. Thus, in FIG. 6G, heat dissipating element  170 ′ is indeed a piece of fabric. For a neck-sized cooling device, fabric  170 ′ might be perhaps 10″ (25.4 cm) in length and perhaps an inch (1 cm) wide, although other dimensions could of course be used. 
     In the embodiment of FIG. 6G, sponge-like material  160  is formed with fabric-facing extensions to define a plurality of plenums  180  between the extensions. This construction permits forming plenums with substantial openings, while simultaneously providing support against the device-facing surface  174 ′ of fabric material  170 ′. Of course more or fewer extensions and plenums could be formed, and different plenums may have different dimensions. In the embodiment of FIG. 6G, unless housing  50  is sufficiently rigid and user-body conforming in shape, belt(s)  177 A/B such as shown in FIG. 5B will be used to secure the device to the user&#39;s body. 
     It will be appreciated that a fabric heat sinking element will be light weight, less expensive to produce, and more conforming than a metal or other more rigid material. If desired, fabric material  170 ′ may include beads  171 , typically a polymer or other material that can absorb moisture. In the embodiment shown in FIG. 6G, housing  50  urges fabric material  170 ′ against sponge-like material  160 . If desired, a wire or plastic grid or mesh could be disposed behind fabric  170 ′ to provide additional rigidity, while still allowing the present invention to flexibly conform to a desired portion of the user&#39;s body. 
     In the embodiment of FIG. 6H, one or more pumps  187  directs a spray  189 ′ of water drawn from reservoir(s)  184 ′ via tubes  185 ′. The pump(s), reservoir(s) and tube(s) may be as described with respect to FIG.  6 C. Augmenting the intake air with a water mist may be used with any or all of the embodiments described herein. It will be appreciated that other fan blade assembly configurations may of course be used. 
     It will be appreciated that essentially any of the disclosed embodiments may be fabricated as modules, to better accommodate fitting to user&#39;s necks, foreheads, etc., having different circumferences. Although more efficient cooling can be promoted by surrounding a greater area of the user&#39;s body portion with the present invention, modular portions of the invention could be spaced-apart from each other along a common belt mechanism. Such belt mechanism would secure the modules, which might measure perhaps one square inch (6.2 cm 2 ) or more each in surface area, along a circumference encompassing the user&#39;s neck or other body portion. Preferably a single battery power supply would drive fan(s) in each module. 
     If desired, other means for indicating moisture content of the liquid-retaining material and/or any reservoirs may be provided. As noted, passive visual means may be chemically implemented. If desired, visual means (e.g., a blinking light emitting diode), audible means (e.g., a beeping sound) could also or instead be provided. If desired, an entertainment device could readily be incorporated into the present invention, for example a small AM-FM radio. The physical appearance of the present invention may also be changed from what has been described or suggested. For example, to minimize moisture loss due to dripping, it may be desirable to locate all vents or ports on an upper region of the device housing. 
     Modifications and variations may be made to the disclosed embodiments without departing from the subject and spirit of the invention as defined by the following claims.