Abstract:
A filter gasket seals at least one mitered corner of a filter frame having a substantially planar first surface and an adjacent side surface. The gasket comprises at least first and second elongated gasket segments formed from compressible material. Each segment has a substantially planar surface adapted to contact the substantially planar first surface of the filter frame. The first and second gasket segments also each include an end which, when brought into joined engagement with the end of the other gasket segment, forms an interlocking miter joint to seal the at least one mitered corner of the filter frame.

Description:
CLAIM OF PRIORITY  
       [0001]    The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/370,683, filed on Aug. 4, 2010, which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND  
       [0002]    There are many circumstances where it is absolutely essential to assure a clean or sterile environment. An obvious example is in hospitals, and especially in operating rooms of hospitals. In the operating room setting, it is the wound site of the patient where sterility is of most importance. Unfortunately, in current approaches, the most critical area of concern, the wound site, is not given primary attention. Rather, current approaches have been just the opposite by giving attention to the condition of the operating room in general in creating a “clean” room without paying special attention to the wound site. This can result in the wound site actually being the area of least cleanliness because it is at the wound site that the most activity occurs during a surgical procedure that both sets contaminants airborne and blocks clean air access to the wound site. 
         [0003]    Contaminated particles can be made up of particulates from any substance, such as dirt and dust, and can include bacterial and virus nebular matter transported either through the air from multiple sources or by touch on surfaces. Neither source of transport can be ignored. The same contaminates can pass from air to surface many times over the course of existence. The present invention addresses the need for establishing a clean air environment at a targeted site, such as, for example, a surgically sterile wound site of a patient. 
       SUMMARY  
       [0004]    In one embodiment, a filter gasket seals at least one mitered corner of a filter frame having a substantially planar top surface and an adjacent side surface. The gasket comprises at least first and second elongated gasket segments formed from compressible material. Each segment has a substantially planar surface adapted to contact the substantially planar first surface of the filter frame. The first and second gasket segments also each include an end which, when brought into joined engagement with the end of the other gasket segment forms an interlocking miter joint to seal the at least one mitered corner of the filter frame. 
         [0005]    The interlocking miter joint may form a substantially right angle joint. The interlocking miter joint has an inside corner and an outside corner. The ends of the gasket segments are configured to form a circuitous seam between the gasket segments from the inner corner to the outer corner. The circuitous seam may include a zigzag seam portion between the gasket segments from the inner corner to the outer corner. 
         [0006]    The ends of the gasket segments may be configured to preclude longitudinal displacement of the joined gasket segments. Each gasket segment includes a tapered surface opposite the planar surface. The gasket segments define an inner edge and an outer edge and the tapered surface of the gasket segments causes the gasket segments to have a decreasing thickness from the outside edge to the inside edge. 
         [0007]    The filter segments may each include an extension extending from the substantially planar surface to wrap around from the substantially planar first surface of the filter frame to and along the adjacent side surface of the filter frame. The filter frame may have an inner edge and an outer edge. The extension of the gasket segments may be configured to wrap around the outer edge of the filter frame. The at least first and second elongated gasket segments are formed from smooth outer surface closed cell compressible material. 
         [0008]    The filter gasket may further include third and fourth elongated gasket segments formed of compressible material. The first, second, third and fourth gasket segments may be arranged to form four substantially right angle miter joints when joined together. Each miter joint may be formed by adjacent segments which form an interlocking miter joint. 
         [0009]    Each interlocking miter joint has an inside corner and an outside corner. The ends of the gasket segments may be configured to form a circuitous seam between the adjacent gasket segments from the inner corner to the outer corner. Each circuitous seam may include a zigzag seam portion between the adjacent gasket segments from the inner corner to the outer corner. 
         [0010]    The ends of the gasket segments may be configured to preclude longitudinal displacement of the joined gasket segments. Each gasket segment may include a tapered surface opposite the planar surface. The gasket segments define an inner edge and an outer edge. The tapered surface of the gasket segments causes the gasket segments to have a decreasing thickness from the outside edge to the inside edge. 
         [0011]    Each filter segment may include an extension extending from the substantially planar surface to wrap around from the substantially planar first surface of the filter frame to and along the adjacent side surface of the filter frame. The filter frame has an inner edge and an outer edge and the extension of each gasket segment may be configured to wrap around the outer edge of the filter frame. 
         [0012]    The gasket segments may be formed from smooth outer surface closed cell compressible material. 
         [0013]    In another embodiment, a filter arrangement comprises a frame including a plurality of frame segments. Each frame segment has a substantially planar first surface and an adjacent side surface. The frame segments may be joined to form a like plurality of mitered joints. The arrangement further includes an ultra-high grade filter media spanning the frame from within the frame segments and a filter gasket that seals the mitered joints of the filter frame. The filter gasket includes a like plurality of elongated gasket segments formed from compressible material. Each segment has a substantially planar surface adapted to contact the substantially planar first surface of a corresponding filter frame segment and an end which, when brought into joined engagement with the end of another one of the gasket segments, forms an interlocking miter joint overlying a corresponding one of the mitered joints of the filter frame. 
         [0014]    Each interlocking miter joint may form a substantially right angle joint. Each interlocking miter joint has an inside corner and an outside corner. The ends of the gasket segments may be configured to form a circuitous seam between adjacent ones of the gasket segments from the inner corner to the outer corner. The circuitous seam may include a zigzag seam portion between the gasket segments from the inner corner to the outer corner. 
         [0015]    The ends of the gasket segments are configured to preclude longitudinal displacement of the joined gasket segments. Each gasket segment may include a tapered surface opposite the planar surface. 
         [0016]    The gasket segments may define an inner edge and an outer edge. The tapered surface of the gasket segments causes the gasket segments to have a decreasing thickness from the outside edge to the inside edge. 
         [0017]    The filter segments may each include an extension extending from the substantially planar surface to wrap around from the substantially planar first surface of the filter frame to and along the adjacent side surface of the filter frame. The filter frame may have an inner edge and an outer edge. The extension of the gasket segments may wrap around the outer edge of the filter frame. The elongated gasket segments may be formed from a smooth outer surface closed cell compressible material. 
         [0018]    In another embodiment, a filter assembly includes a filter arrangement comprising a frame including a plurality of frame segments. Each frame segment has a substantially planar first surface and an adjacent side surface. The frame segments are joined to form a like plurality of mitered joints. An ultra-high grade filter media spans the frame from within the frame segment. The assembly further includes a filter gasket that seals the mitered joints of the filter frame. The filter gasket includes a like plurality of elongated gasket segments formed from compressible material. Each segment has a substantially planar surface adapted to contact the substantially planar first surface of a corresponding filter frame segment and an end which, when brought into joined engagement with the end of another one of the gasket segments forms an interlocking miter joint overlying a corresponding one of the mitered joints of the filter frame. The assembly further includes a receptacle having wall segments configured to receive the filter arrangement, to compress the interlocking gasket miter joints together and to compress the compressible gasket material along the elongated gasket segments. 
         [0019]    Each interlocking miter joint may be configured to form a substantially right angle joint. Each interlocking miter joint has an inside corner and an outside corner. The ends of the gasket segments may be configured to form a circuitous seam between adjacent ones of the gasket segments from the inner corner to the outer corner. The circuitous seam may include a zigzag seam portion between the gasket segments from the inner corner to the outer corner. 
         [0020]    The ends of the gasket segments may be configured to preclude longitudinal displacement of the joined gasket segments. Each gasket segment may include a tapered surface opposite the planar surface. The gasket segments may be configured to define an inner edge and an outer edge and the tapered surface of the gasket segments causes the gasket segments to have a decreasing thickness from the outside edge to the inside edge. 
         [0021]    Each filter segment may include an extension extending from the substantially planar surface to wrap around from the substantially planar first surface of the filter frame to and along the adjacent side surface of the filter frame. The filter frame may be configured to have an inner edge and an outer edge. The extension of the gasket segments may then wrap around the outer edge of the filter frame. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0022]    The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with further features and advantages thereof, may best be understood by making reference to the following description taken in conjunction with the accompanying drawings, in the several figures of which like reference numerals identify identical elements, and wherein: 
           [0023]      FIG. 1  is a simplified view of an operating room with a patient on an operating table and placed within a focused clean air zone column according to aspects of the present invention; 
           [0024]      FIG. 2  is a diagram illustrating a focused clean air zone column profile for a focused clean air zone column formed by the movement of ultra-clean air from an ultra-high grade filter at a velocity of 90 feet per minute; 
           [0025]      FIG. 3  is another simplified view of an operating room with a patient on an operating table and placed within a focused clean air zone column according to further aspects of the present invention; 
           [0026]      FIG. 4  is a diagram illustrating a focused clean air zone column profile for a focused clean air zone column formed by the movement of ultra-clean air from an ultra-high grade filter at a velocity of 120 feet per minute; 
           [0027]      FIG. 5  is a partial perspective view of a ceiling having a filter unit embodying aspects of the present invention mounted within T-bar supports of the ceiling; 
           [0028]      FIG. 6  is a side view of a filter unit embodying aspects of the present invention mountable within the ceiling of  FIG. 5 ; 
           [0029]      FIG. 7  is a top plan view of a filter arrangement which may be employed in the filter unit of  FIG. 6  according to further aspects of the invention; 
           [0030]      FIG. 8  is a partial plan view of a gasket employed in the filter arrangement of  FIG. 7  according to further aspects of the present invention; 
           [0031]      FIG. 9  is a partial side view illustrating the filter arrangement of  FIG. 7  being placed within a filter receptacle of the filter unit of  FIG. 6  to form a filter assembly according to aspects of the invention; and 
           [0032]      FIG. 10  is partial side view of the filter assembly of  FIG. 9  ready for use according to still further aspects of the invention. 
       
    
    
     DETAILED DESCRIPTION  
       [0033]    Referring now to  FIG. 1 , it shows an operating room  20  having a ceiling  22  and a floor  24 . Also shown is a patient  26  in need of a surgical procedure disposed in a supine position on an operating table  28 . 
         [0034]    Above the patient and mounted within the ceiling  22  is a ceiling mounted filter unit  30  embodying the present invention. The filter unit includes an ultra-high grade filter  32  and a blower  34 . Air enters the filter unit  30  through an intake  36 . 
         [0035]    The ultra-grade filter may be a high efficiency particle arrestor (HEPA) filter, an ultimate level particle arrester (ULPA) filter, or any other filter having filter characteristics the same as or better than a HEPA filter efficiency grade. HEPA filters are 99.99 percent or greater efficient for particles at 0.3 microns in size and larger. ULPA filters are 99.999 percent or greater efficient for particles at 0.1 microns in size and larger. 
         [0036]    The air provided to intake  36  may be from the building regular air supply directly or indirectly connected. Alternatively, the air supplied to intake  36  may to some degree be pre-filtered. 
         [0037]    The blower  34  forms an air flow generator that pulls air from the intake  36  and forces the air through the filter  32 . It may be an impeller blower, for example. Alternatively the blower may be an axial blower or a housed blower. 
         [0038]    The blower is operable to force air  37  from the filter face  38  at a velocity between 70 feet per minute to 200 feet per minute. The ultra-clean air exiting the filter  32  within that velocity range will form a focused clean air zone column  40  extending from the filter face  38 . The focused clean air zone column  40  has a profile comprising a plurality of zones  42 ,  44 ,  46 , and  48 . Each zone represents a minimum number of airborne particles per cubic foot of air. The profile of the focused clean air zone column will be described more completely subsequently. 
         [0039]    The operating table  28  is arranged to place the patient  26  into a position whereby the critical surgical wound site of the patient  26  will be within zone  48  of the focused clean air zone column  40 . This assures that the surgical wound site will be within surgically clean air. 
         [0040]    The focused clean air column  40  commences at the point the airflow projection expels into a surrounding air from the rigid enclosure and filter. Here, the focused clean air column  40  commences at the filter exhaust side face  38 . The air flows as a nearly single mass with the air across the column flowing at nearly the same velocity, thereby creating laminar flow. The air that is constantly being expelled is pushing the air mass in front until all of the energy is expended. 
         [0041]      FIG. 2  shows the profile of the focused clean air zone column  40  of  FIG. 1  for an initial air flow velocity at the filter face  38  of 90 feet per minute. As the air flows out from the filter, air outside of the column  40  will begin to mix with the air within the column along the corresponding edges  40 . However, by virtue of the laminar flow of the air and the initial cleanliness of the air at the filter face  38 , the air within the column  40  remains extremely clean throughout the length of the column  40 . To that end, the first zone  42  extends out to about 1.5 feet and contains less than 100 particles per cubic foot of air. The second zone  44  extends out to about 2.5 feet and contains less than 150 particles per cubic foot of air. The third zone  46  extends out to about just over 4 feet and contains less than 200 particles per cubic foot of air. Lastly, the fourth zone  46  extends out to over 6 feet and contains less than 300 particles per cubic foot of air. As shown in  FIG. 1 , the patient is disposed within the fourth zone  48 . Any one of these zones would provide sufficiently clean air to support a surgical procedure within a surgically clean air environment at the serial field target. 
         [0042]      FIG. 2  also shows the air velocity for air flow out from the filter  32 . At 4 feet out, for example, the air flow velocity is about 50 feet per minute. It is important that the air velocity not be so high as to cause rapid drying of tissue at the surgical wound site or create turbulence within the zone thereby reducing its effectiveness. All of the air velocities shown in  FIG. 2  are well below such an air velocity. However, all of the air flow velocities illustrated are sufficient to provide an additional important function. That is to force any contaminants  54  ( FIG. 1 ) created during the surgery and other undesirable airborne side products from the surgery, such as cauterization smoke, to be forced downward gently towards the floor and away and down below the surgical wound site and the operating room personnel upper portion of their bodies without any bounce back of the contaminated smoke filled air into critical areas off nearby objects or the floor. 
         [0043]    Referring now to  FIG. 3 , it shows another operating room  120  having a focused clean air zone column  140  extending therein formed by an initial air velocity of 120 feet per minute. The operating room  120  has a ceiling  122  and a floor  124 . Also shown is a patient  126  in need of a surgical procedure disposed in a supine position on an operating table  128 . 
         [0044]    Above the patient and mounted within the ceiling  122  is a ceiling mounted filter unit  130  embodying the present invention. The filter unit includes an ultra-high grade filter  132  and a blower  134 . Air enters the filter unit  130  through an intake  136 . 
         [0045]    As in the previous embodiment, the ultra-grade filter may be a high efficiency particle arrestor (HEPA) filter, an ultimate level particle arrester (ULPA) filter, or any other filter having filter characteristics the same as or better than a HEPA filter. HEPA filters are 99.99 percent efficient for particles at 0.3 microns in size or larger. 
         [0046]    The air provided to intake  136  may be from the building regular air supply. Alternatively, the air supplied to intake  136  may to some degree be pre-filtered. 
         [0047]    The blower  134  forms an air flow generator. As in the previous embodiment, it may be an impeller blower, for example. Alternatively the blower may be an axial blower or a housed blower. 
         [0048]    The blower is operable to force air  137  from the filter face  138  at a velocity of 120 feet per minute, within the 70 feet per minute to 200 feet per minute velocity range previously mentioned. The ultra-clean air exiting the filter  132  at those velocities will thus form the focused clean air zone column  140  extending from the filter face  138 . The focused clean air zone column  140  has a profile comprising a plurality of zones  142 ,  144 ,  146 , and  148 . Again, each zone represents a minimum number of airborne particles per cubic foot of air. 
         [0049]    The operating table  128  is arranged to place the patient  126  into a position whereby the surgical wound site of the patient  126  will be within zone  146  of the focused clean air zone column  140 . This assures that the surgical wound site will be within surgical quality clean air. 
         [0050]    The focused clean air zone column  140  commences at the filter face  38 . Because the initial flow velocity is within the 70 to 200 foot per minute velocity range, the air flows as a nearly single mass with the air across the column flowing at nearly uniform velocity in laminar flow. 
         [0051]      FIG. 4  shows the profile of the focused clean air zone column  140  of  FIG. 3 . As the air flows out from the filter, air outside of the column  140  will begin to mix with the air within the column  140 . However, by virtue of the laminar flow of the air and the initial cleanliness of the air at the filter face  138 , the air within the column  140  remains extremely clean throughout the length of the column  140 . To that end, the first zone  142  extends out to just over 2 feet and contains less than 100 particles per cubic foot of air. The second zone  144  extends out to just over 3.5 feet and contains less than 150 particles per cubic foot of air. The third zone  146  extends out to about just over 5.5 feet and contains less than 200 particles per cubic foot of air. Lastly, the fourth zone  148  extends out to over 7 feet and contains less than 300 particles per cubic foot of air. Any one of these zones would provide sufficiently clean air to support a surgical procedure within a surgically clean air environment. As may be realized from the profile of  FIG. 2  representing an initial air flow velocity of 90 feet per minute and the profile of  FIG. 4  representing an initial air flow velocity 120 feet per minute, the focused clean air zone columns are similar except that the column formed with an initial velocity of 120 feet per minute extends out farther than the column formed with an initial velocity of 90 feet per minute. 
         [0052]      FIG. 4  also shows the air velocity for air flow out from the filter  132 . While the air flow velocities represented in the profile of  FIG. 4  are higher than in the profile of  FIG. 2 , the air flow velocities shown in  FIG. 4  are still not so high as to cause rapid drying of tissue at the surgical open wound site. All of the air velocities shown in  FIG. 4  are well below such an air velocity. 
         [0053]      FIG. 5  is a partial perspective view of a ceiling  222  having a filter unit  230  mounted within the T-bar supports of the ceiling. In the arrangement of  FIG. 5 , intake air may most readily be obtained from the building HVAC system. However, the intake air may be obtained from other sources as well and may even be pre-filtered to some extent. While hospitals and hospital operating rooms would not generally use T-bar ceiling supports, such a ceiling is shown herein to emphasize the point that a surgically clean air targeted air environment may be obtain in most any room or space by practicing the embodiments of the invention. 
         [0054]      FIG. 6  is a side view of the filter unit  230  embodying aspects of the present invention which may be mounted within the ceiling of  FIG. 5  or used in most any application according to the invention, including within hospitals and operating rooms. The filter unit includes a filter housing or receptacle  231  and a blower housing  233 . The filter receptacle  231  contains a filter arrangement to be described subsequently which includes an ultra-high grade filter (not shown). The blower housing  233  contains an impeller blower  234 . Air enters the filter unit  230  through an intake  236 . The interior  235  of the blower housing  233  forms a plenum chamber which, along with the back pressure provided by the ultra-high grade filter, causes the air flow  237  from the blower  234  to be evenly distributed across the filter face  238 . The blower  234  is operable to force the air through the filter at initial air flow velocities from 70 feet per minute to 200 feet per minute. This causes a focused clean air zone column  240  of air to extend form the filter face  238 . 
         [0055]    The filter receptacle  231  includes a door panel that is hingedly connected to the filter receptacle  231  by hinges  243 . The hinged door  241  permits ready exchanges of filters when required. 
         [0056]    When a filter is placed within the filter receptacle  231 , it is important that the perimeter of the filter is well sealed to preclude unclean ambient air from circulating around the filter and entering the room in an unfiltered condition. Such an occurrence could carry most serious consequences. More particularly, the seal should be provided along the perimeter of the filter between the filter and the receptacle. Experience has shown that obtaining such a reliable seal is most difficult in the corners of the filter. 
         [0057]    In accordance with the present invention, a secure and reliable seal is obtained about the ultra-high grade filter by a filter arrangement  250  shown in  FIGS. 7-10 . The filter arrangement  250  in  FIGS. 7-10  may be employed to advantage in any of the embodiments previously described and provides such a secure seal in accordance with the present invention. The filter arrangement  250  includes a frame  252 , a gasket  254 , and an ultra-high grade filter media  256 . 
         [0058]    The frame  252  includes a plurality of frame segments  262 ,  264 ,  266 , and  268 . Each frame segment has a substantially planar first surface and an adjacent side surface. To illustrate, as seen in  FIGS. 7 and 9 , segment  268  has a substantially planar first surface  269  and an adjacent side surface  271 . The frame segments are joined in series to form a like plurality of miter joints.  FIG. 8  shows the miter joint  274  formed between frame segment  268  and frame segment  262 . The frame miter joints, such as miter joint  274 , are potentials sources for air leaks that must be addressed. As may be seen in  FIG. 7 , the ultra-high grade filter media  256  spans the frame segments  262 ,  264 ,  266 , and  268  and as best seen in  FIGS. 9 and 10 , terminates within the filter frame  252 . 
         [0059]    The gasket  254  includes a like plurality of elongated gasket segments  282 ,  284 ,  286 , and  288 . The gasket segments may be formed from compressible material, such as closed cell neoprene treated to have a smooth outer surface. Each gasket segment has a substantially planar surface adapted to contact the substantially planar first surface of a corresponding filter segment. To illustrate, as may be seen in  FIG. 9 , the gasket segment  288  has a substantially planar surface  289  that makes broad surface contact with the substantially planar surface  269  of the frame segment  268 . Also, each gasket segment has an extension extending from the substantially planar surface to wrap around, from the substantially planar first surface of the filter frame to and along the adjacent side surface of the filter frame. To that end, it may be seen in  FIG. 9  that gasket segment  288  has an extension  267  that wraps around, from the substantially planar first surface  269  of the filter frame to and along the adjacent side surface  271  of the filter frame. 
         [0060]    Still further, each gasket segment has a tapered surface opposite its substantially planar surface. For example, as may be seen in  FIG. 9 , the gasket segment  288  has a tapered surface  275  opposite the substantially planar surface  289 . The tapered surface is formed so as to have a decreasing thickness from the outer edge of the gasket to the inner edge of the gasket. 
         [0061]    As may be noted from the above, the gasket  254  is arranged to overlie and wrap around the filter frame  252 . In the corners, the gasket overlies the miter joints of the filter frame with an interlocking miter joint. To that end, as may be noted in  FIG. 7 , the ends of the gasket segments are configured and joined together to provide gasket  262  with substantially right angle interlocking miter joints  290 ,  292 ,  294 , and  296 . Each of the interlocking miter joints overlies a corresponding miter joint of the filter frame. As may be best seen in  FIG. 8 , the interlocking miter joint  290  is shown in greater detail. The ends of the gasket segments  288  and  282  are configured to form a circuitous zigzag seam  291  to form the interlocking miter joint  290 . This structure is repeated for all four corners of the gasket  254 . The circuitous interlocking miter joints are configured to preclude longitudinal displacement of the gasket segments after they are joined. More particularly, the ends of gasket segments  282  and  288  are shaped to resist displacement of the segments along the longitudinal lines  295  and  297  shown in  FIG. 8 . This improves manufacturability of the gasket. The circuitous path of the interlocking miter joints also importantly provides a reliable seal at the filter frame corners to outside, unfiltered air. 
         [0062]      FIG. 10  shows the filter arrangement  250  received within the filter receptacle  231  to complete the filter unit  230  of  FIG. 6 . The air moves through the filter arrangement in the direction of arrows  237 . Here it may be seen that the gasket  254  is compressed by the receptacle. Such compression occurs along the entire perimeter of the gasket, including the gasket corners. To that end, a first seal  311  is formed, a second seal  313  is formed, and a third seal is formed along the interlocking miter joints. In addition, when the filter arrangement  250  is received within the receptacle  231 , the compression of the gasket segments forces the segments into the receptacle corners to enhance the sealing effect of the interlocking miter joints of the gasket. 
         [0063]    While particular embodiments of the present invention have been shown and described, modifications may be made, and it is therefore intended in the appended claims to cover all such changes and modifications which fall within the true spirit and scope of the invention as defined by those claims.