Patent Publication Number: US-11647881-B2

Title: Cleaning apparatus with combing unit for removing debris from cleaning roller

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of U.S. Provisional Application No. 62/469,853, filed Mar. 10, 2017 and is a continuation-in-part of U.S. patent application Ser. No. 15/331,045, filed Oct. 21, 2016, which claims the benefit of U.S. Provisional Patent Application Ser. No. 62/244,331 filed Oct. 21, 2015, U.S. Provisional Patent Application Ser. No. 62/248,813 filed Oct. 30, 2015, and U.S. Provisional Patent Application Ser. No. 62/313,394 filed Mar. 25, 2016, all of which are fully incorporated herein by reference. The present application is also a continuation-in-part of International Application No. PCT/US2016/058148, filed on Oct. 21, 2016, which is fully incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to cleaners with cleaning rollers and more particularly, to a cleaning apparatus, such as a surface cleaning head for a vacuum cleaner, with a combing unit for removing debris from a cleaning roller such as a leading roller. 
     BACKGROUND INFORMATION 
     Vacuum cleaners generally include a suction conduit with an opening on the underside of a surface cleaning head for drawing air (and debris) into and through the surface cleaning head. One of the challenges with vacuum cleaner design is to control engagement of the suction conduit with a surface being cleaned to provide the desired amount of suction. If the suction conduit is spaced too far from a surface, the suction may be less because the air is flowing into the suction conduit through a greater surface area. If the suction conduit is directly engaged with the surface and thus sealed on all sides, air will stop flowing into the suction conduit and the suction motor may be damaged as a result. 
     Vacuum cleaners also generally use agitation to loosen debris and facilitate capturing the debris in the flow of air into the suction conduit. Agitators are often used in the suction conduit of a surface cleaning head proximate a dirty air inlet to cause the agitated debris to flow into the dirty air inlet. If the agitator in the suction conduit is unable to loosen the debris or if the debris is too small, the suction conduit may pass over the debris without removing the debris from the surface. In other cases, the surface cleaning head may push larger debris forward without ever allowing the debris to be captured in the flow into the suction conduit (sometimes referred to as snowplowing). 
     One example of an agitator is a cleaning roller such as a brush roll. A cleaning roller may be located within a suction conduit and/or may be located at a leading side of a suction conduit (e.g., a leading roller). One challenge with a leading roller in particular is the debris (e.g., hair) that becomes entangled around the roller. Projections may be used to engage the roller to facilitate removal of debris, but existing structures are often not effective and/or interfere with the operation of the surface cleaning head. 
     SUMMARY 
     Consistent with an embodiment, a cleaning apparatus includes a housing defining an opening on an underside of the housing for receiving debris, a cleaning roller mounted in the housing for directing debris into the opening, and a combing unit extending a substantial length of a cleaning surface of the cleaning roller and in contact with the cleaning roller. The combing unit includes a series of spaced combing protrusions extending partially into the cleaning roller and having angled leading edges that are not aligned with a center of rotation of the cleaning roller. The angled leading edges are directed into a direction of rotation of the cleaning roller. 
     Consistent with another embodiment, a surface cleaning head includes a housing having a front side and back side. The housing defines a suction conduit with an opening on an underside of the housing between the front side and the back side. A brush roll is rotatably mounted to the housing within the suction conduit and at least a portion of the brush roll is proximate the opening of the suction conduit. A leading roller is mounted to the housing in front of the brush roll and adjacent the opening of the suction conduit. A front portion of the leading roller is at least partially exposed at the front side of the housing. The surface cleaning head also includes a combing unit extending a substantial length of a cleaning surface of the leading roller and in contact with the leading roller. The combing unit includes a series of spaced combing protrusions extending partially into the leading roller and having angled leading edges that are not aligned with a center of rotation of the leading roller. The angled leading edges are directed toward a direction of rotation of the leading roller. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features and advantages will be better understood by reading the following detailed description, taken together with the drawings wherein: 
         FIG.  1    is a perspective view of a surface cleaning head including dual agitators and combing protrusions, consistent with an embodiment of the present disclosure. 
         FIG.  2    is a side cross-sectional view of the surface cleaning head shown in  FIG.  1    showing a flow path through a suction conduit. 
         FIG.  3    is an enlarged side cross-sectional view illustrating the leading roller and brush roll of the surface cleaning head shown in  FIG.  1   . 
         FIG.  4    is an enlarged side cross-sectional view illustrating a leading roller and combing protrusions in the surface cleaning head shown in  FIG.  1   . 
         FIG.  5    is a front perspective view of the front region of the surface cleaning head of  FIG.  1    without the leading roller and illustrating the combing protrusions. 
         FIG.  6    is an enlarged perspective view of one embodiment of a plurality of combing protrusions. 
         FIG.  7    is a front bottom view of the front region of the surface cleaning head of  FIG.  1    without the leading roller. 
         FIG.  8    is a front view the surface cleaning head of  FIG.  1   . 
         FIG.  9    is a bottom view the surface cleaning head of  FIG.  1   . 
         FIG.  10    is a perspective cross sectional view of combing protrusions engaging a cleaning roller, consistent with an embodiment of the present disclosure. 
         FIG.  11    is a side cross-sectional view of the combing protrusions engaging the cleaning roller. 
         FIG.  12    is a side perspective view of the combing protrusions shown in  FIG.  10   . 
         FIG.  13    is a top perspective view of a section of the combing protrusions shown in  FIG.  10   . 
         FIGS.  14 A- 14 D  are top, front, bottom and side views of the section of combing protrusions shown in  FIG.  13   . 
         FIG.  15 A  is a side cross-sectional view of the combing protrusions engaging a cleaning roller above an axis of rotation, consistent with another embodiment. 
         FIG.  15 B  is a side cross-sectional view of a combing protrusion having a curved leading edge engaging a cleaning roller, consistent with a further embodiment. 
         FIG.  16    is a perspective view of an upright vacuum cleaner including a surface cleaning head with dual rotating agitators and combing protrusions, consistent with embodiments of the present disclosure. 
         FIG.  17    is a perspective view of a stick type vacuum cleaner including a surface cleaning head with dual rotating agitators and combing protrusions, consistent with embodiments of the present disclosure. 
         FIG.  18    is a bottom perspective view of a robotic vacuum cleaner including a cleaning roller and combing protrusions, consistent with yet another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     A cleaning apparatus, consistent with embodiments of the present disclosure, includes a combing unit (also referred to as a debriding unit or rib) including a series of spaced protrusions or teeth extending into a cleaning roller for preventing build up and removing debris (such as hair, string, and the like). The protrusions extend along a substantial portion of the cleaning roller and extend partially into the cleaning roller to intercept the debris as it passes around the roller. The protrusions have angled leading edges that are not aligned with a rotation center of the cleaning roller and are directed into or against a direction of rotation of the cleaning roller. The combing unit and protrusions have a shape and configuration designed to facilitate debris removal from the cleaning roller with minimal impact on the operation of the cleaning apparatus. The cleaning apparatus may include a surface cleaning head of an upright vacuum cleaner or sweeper or a robotic vacuum cleaner. 
     An embodiment of a surface cleaning head may include dual rotating agitators (e.g., a leading roller and a brush roll) and may be used to facilitate capturing of debris in the air flow into a suction conduit on the underside of the surface cleaning head. In this embodiment, the leading roller is generally positioned adjacent to and in advance of the opening of the suction conduit such that the leading roller engages debris and moves the debris toward the opening. At least a top half of the leading roller may be substantially outside of the flow path to the suction conduit and a bottom portion of the leading roller may be exposed to the flow path to the suction conduit. The rotating brush roll may be located in the suction conduit with the leading roller located in front of and spaced from the brush roll, forming an inter-roller air passageway between lower portions of the leading roller and the brush roll. In some embodiments, combing protrusions may contact the leading roller above the inter-roller air passageway to facilitate debris removal into the flow path. The surface cleaning head may also include a leading bumper that extends in front of the leading roller to protect a front portion of the leading roller and facilitate front edge cleaning. 
     Although specific embodiments of a surface cleaning head with a leading roller are shown, other embodiments of a cleaning apparatus with a combing unit are within the scope of the present disclosure. The cleaning apparatus with the combing unit may be used in different types of vacuum cleaners including, without limitation, an “all in the head” type vacuum, upright vacuum cleaners, canister vacuum cleaners, stick vacuum cleaners, robotic vacuum cleaners and central vacuum systems, and may be used in sweepers (e.g., low or no suction). The surface cleaning head with a leading roller may also include removable agitators (e.g., brush rolls) in openable agitator chambers, such as the type described in greater detail in U.S. Pat. No. 9,456,723 and U.S. Patent Application Pub. No. 2016/0220082, which are commonly-owned and fully incorporated herein by reference. The leading roller may be similarly removable. 
     As used herein, a “surface cleaning head” refers to a device configured to contact a surface for cleaning the surface by use of suction air flow, agitation, or a combination thereof. A surface cleaning head may be pivotably or steeringly coupled by a swivel connection to a wand for controlling the surface cleaning head and may include motorized attachments as well as fixed surface cleaning heads. A surface cleaning head may also be operable without a wand or handle. As used herein, “seal” or “sealing” refers to preventing a substantial amount of air from passing through to the suction conduit but does not require an air tight seal. As used herein, “agitator” refers to any element, member or structure capable of agitating a surface to facilitate movement of debris into a suction air flow in a surface cleaning head. As used herein, “soft” and “softer” refer to the characteristics of a cleaning element being more compliant or pliable than another cleaning element. As used herein, the term “flow path” refers to the path taken by air as it flows into a suction conduit when drawn in by suction. As used herein, the terms “above” and “below” are used relative to an orientation of the surface cleaning head on a surface to be cleaned and the terms “front” and “back” are used relative to a direction that a user pushes the surface cleaning head on a surface being cleaned (i.e., back to front). As used herein, the term “leading” refers to a position in front of at least another component but does not necessarily mean in front of all other components. 
     Referring to  FIGS.  1 - 9   , an embodiment of a surface cleaning head  100  with dual agitators and a combing unit is shown and described. The surface cleaning head  100  includes a housing  110  with a front side  112 , and a back side  114 , left and right sides  116   a ,  116   b , an upper side  118 , and a lower or under side  120 . The housing  110  defines a suction conduit  128  having an opening  127  on the underside  120  of the housing (shown in  FIGS.  2  and  3   ). The suction conduit  128  is fluidly coupled to a dirty air inlet  129 , which leads to a suction motor (not shown) either in the surface cleaning head  100  or another location in the vacuum. The suction conduit  128  is the interior space defined by interior walls in the housing  110 , which receives and directs air drawn in by suction, and the opening  127  is where the suction conduit  128  meets the underside  120  of the housing  110 . 
     The surface cleaning head  100  includes dual rotating agitators  122 ,  124 , for example, a brush roll  122  and a leading roller  124 . The brush roll  122  and leading roller  124  may be configured to rotate about first and second rotating axes (RA 1 , RA 2 ). The rotating brush roll  122  is at least partially disposed within the suction conduit  128  (shown in  FIGS.  2  and  3   ). The leading roller  124  is positioned in front of and spaced from the brush roll  122  and at least substantially outside the suction conduit  128 . In some embodiments, at least an inside upper portion (e.g., upper half) of the leading roller  124  is not exposed to the primary air flow path (e.g., arrow  40 ) into the opening  127  of the suction conduit  128  while at least an inside of the bottom portion of the leading roller  124  is exposed to the primary flow path into the opening  127  of the suction conduit  128 . 
     Other variations are possible where different portions of the leading roller  124  may be exposed or not exposed to the flow path into the suction conduit  128 . In other embodiments, for example, a flow path may allow air to flow over the upper portion of the leading roller  124 . The leading roller  124  may rotate about the second rotation axis RA 2  located within a leading roller chamber  126 . The leading roller chamber  126  may have a size and shape slightly larger than the cylindrical projection of the leading roller  124  when the leading roller  124  is rotating therein, for example, to form the flow path over the upper portion. 
     The surface cleaning head  100  may include one or more wheels  130  for supporting the housing on the surface  10  to be cleaned. The brush roll  122  may be disposed in front of one or more wheels  130 ,  132  (see  FIGS.  1  and  9   ) for supporting the housing  110  on the surface  10  to be cleaned. For example, one or more larger wheels  130  may be disposed along the back side  114  and/or one or more smaller middle wheels  132  may be provided at a middle section on the underside  116  of the housing  110  and/or along the left and right sides  116   a ,  116   b . Other wheel configurations may also be used. The wheels  130 ,  132  facilitate moving the surface cleaning head  100  along the surface  10  to be cleaned, and may also allow the user to easily tilt or pivot the surface cleaning head  100  (e.g., brush roll  122  and/or the leading roller  124 ) off of the surface  10  to be cleaned. The rear wheel(s)  130  and the middle wheel(s)  132  may provide the primary contact with the surface being cleaned and thus primarily support the surface cleaning head  100 . When the surface cleaning head  100  is positioned on the surface  10  being cleaned, the leading roller  124  may also rest on the surface  10  being cleaned. In other embodiments, the leading roller  124  may be positioned such that the leading roller  124  sits just above the surface being cleaned. 
     The rotating brush roll  122  may have bristles, fabric, or other cleaning elements, or any combination thereof around the outside of the brush roll  122 . Examples of brush rolls and other agitators are shown and described in greater detail in U.S. Pat. No. 9,456,723 and U.S. Patent Application Pub. No. 2016/0220082, which are fully incorporated herein by reference. 
     The leading roller  124  may include a relatively soft material (e.g., soft bristles, fabric, felt, nap or pile) arranged in a pattern (e.g., a spiral pattern) to facilitate capturing debris, as will be described in greater detail below. The leading roller  124  may be selected to be substantially softer than that of the brush roll  122 . The softness, length, diameter, arrangement, and resiliency of the bristles and/or pile of the leading roller  124  may be selected to form a seal with a hard surface (e.g., but not limited to, a hard wood floor, tile floor, laminate floor, or the like), whereas the bristles of the brush roll  122  may selected to agitate carpet fibers or the like. For example, the leading roller  124  may be at least 25% softer than the brush roll  122 , alternatively the leading roller  124  may be at least 30% softer than the brush roll  122 , alternatively the leading roller  124  may be at least 35% softer than the brush roll  122 , alternatively the leading roller  124  may be at least 40% softer than the brush roll  122 , alternatively the leading roller  124  may be at least 50% softer than the brush roll  122 , alternatively the leading roller  124  may be at least 60% softer than the brush roll  122 . Softness may be determined, for example, based on the pliability of the bristles or pile being used. 
     The size and shape of the bristles and/or pile may be selected based on the intended application. For example, the leading roller  124  may include bristles and/or pile having a length of between 5 to 15 mm (e.g., 7 to 12 mm) and may have a diameter of 0.01 to 0.04 mm (e.g., 0.01-0.03 mm). According to one embodiment, the bristles and/or pile may have a length of 9 mm and a diameter of 0.02 mm. The bristles and/or pile may have any shape. For example, the bristles and/or pile may be linear, arcuate, and/or may have a compound shape. According to one embodiment, the bristles and/or pile may have a generally U and/or Y shape. The U and/or Y shaped bristles and/or pile may increase the number of points contacting the floor surface  10 , thereby enhancing sweeping function of leading roller  124 . The bristles and/or pile may be made on any material such as, but not limited to, Nylon  6  or Nylon  6 / 6 . 
     Optionally, the bristles and/or pile of leading roller  124  may be heat treated, for example, using a post weave heat treatment. The heat treatment may increase the lifespan of the bristles and/or pile of the leading roller  124 . For example, after weaving the fibers and cutting the velvet into rolls, the velvet may be rolled up and then run through a steam rich autoclave making the fibers/bristles more resilient fibers. 
     The leading roller  124  may have an outside diameter Dlr that is smaller than the outside diameter Dbr of the brush roll  122 . For example, the diameter Dlr may be greater than zero and less than or equal to 0.8 Dbr, greater than zero and less than or equal to 0.7 Dbr, or greater than zero and less than or equal to 0.6 Dbr. According to example embodiments, the diameter Dlr may be in the range of 0.3 Dbr to 0.8 Dbr, in the range of 0.4 Dbr to 0.8 Dbr, in the range of 0.3 Dbr to 0.7 Dbr, or in the range of 0.4 Dbr to 0.7 Dbr. As an illustrative example, the brush roll  122  may have an outside diameter of 48 mm and the leading roller  124  may have an outside diameter of 30 mm. While the leading roller  124  may have an outside diameter Dlr that is smaller than the outside diameter Dbr of the brush roll  122 , the brush roll  122  may have bristles that are longer than the bristle and/or pile of the leading roller  122 . 
     Positioning a leading roller  124  (having a diameter Dlr that is smaller than the diameter Dbr of the brush roll  122 ) in front of the brush roll  122  provides numerous benefits. For example, this arrangement decreases the height of the front side  112  of the surface cleaning head  100  (e.g., the housing  110 ) from the surface  10  to be cleaned. The decreased height of the front of the surface cleaning head  100  provides a lower profile that allows the surface cleaning head  100  to fit under objects (e.g., furniture and/or cabinets). Moreover, the lower height allows for the addition of one or more light sources  111  (such as, but not limited to, LEDs), while still allowing the surface cleaning head  100  to fit under objects. 
     Additionally, the smaller diameter Dlr of the leading roller  124  allows the rotating axis of the leading roller  124  to be placed closer to the front side  112  of the surface cleaning head  100 . When rotating, the leading roller  124  forms a generally cylindrical projection having a radius that is based on the overall diameter of the leading roller  124 . As the diameter of the leading roller  124  decreases, the bottom contact surface  140  ( FIG.  3   ) of the leading roller  124  moves forward towards the front side  112  of the surface cleaning head  100 . In addition, when the surface cleaning head  100  contacts a vertical surface  12  (e.g., but not limited to, a wall, trim, and/or cabinet), the bottom contact surface  140  of the leading roller  124  is also closer to the vertical surface  12 , thereby enhancing the front edge cleaning of the surface cleaning head  100  compared to a larger diameter leading roller. Moreover, the smaller diameter Dlr of the leading roller  124  also reduces the load/drag on the motor driving the leading roller  124 , thereby enhancing the lifespan of the motor and/or allowing a smaller motor to be used to rotate both the brush roll  122  and leading roller  124 . 
     The rotating brush roll  122  may be coupled to an electrical motor (either AC or DC) to cause the rotating brush roll  122  to rotate about the first rotating axis. The rotating brush roll may be coupled to the electrical motor by way of a gears and/or drive belts. The leading roller  124  may be driven from the same drive mechanism used to drive the rotating brush roll  122  or a separate drive mechanism. An example of the drive mechanism is described in U.S. patent application Ser. No. 15/331,045, filed Oct. 21, 2016, which is incorporated herein by reference. Other drive mechanisms are possible and within the scope of the present disclosure. 
     In at least one embodiment, the brush roll  122  and the leading roller  124  rotate in the same direction directing debris toward the suction conduit  128 , for example, counter clockwise as shown in  FIG.  3   . This arrangement may reduce the number of parts (e.g., no clutch or additional gear train may be necessary), thereby making the surface cleaning head  100  lighter, reducing drivetrain loss (thereby allowing for smaller/less expensive motors), and less expensive to manufacture. Optionally, the brush roll  122  and the leading roller  124  may rotate at same speed, thereby reducing the number of parts (e.g., no additional gear train necessary) and reducing drivetrain loss (thus, smaller/less expensive motor) and making the surface cleaning head  100  lighter and less expensive to manufacture. 
     As shown in  FIG.  3   , the leading roller  124  may be positioned within the housing  110  such that the bottom contact surface  140  is disposed closer to the surface  10  to be cleaned compared to the bottom contact surface  144  of the brush roll  122 . This arrangement allows the leading roller  124  to contact a surface  10  (e.g., a hard surface) without the brush roll  122  contacting the hard surface  10 . As may be appreciated, the leading roller  124  is intended to pick up debris from a hard surface  10  while the brush roll  122  is intended to primarily contact a carpet surface. This arrangement is therefore beneficial since it allows the leading roller  124  to form a seal between the front  112  of the surface cleaning head  100  with the hard surface  10 , thereby enhancing airflow and suction with the hard surface  10 . Additionally, this arrangement reduces the drag/torque on the drive motor(s) since the brush roll  122  (in some embodiments) does not have to contact the hard surface  10 . The reduced drag/torque may allow for a smaller, less expensive motor and/or may increase the lifespan of the motor. 
     According to some embodiments, as shown in  FIG.  3   , the leading roller  124  is spaced apart a distance L 1  (which is greater than 0 mm) from the brush roll  122  such that the leading roller  124  does not contact the brush roll  122 . The distance L 1  allows for an inter-roller vacuum passageway  146  between lower portions of the brush roll  122  and the leading roller  124 , which provides at least a portion of the flow path into the opening  127  of the suction conduit  128 . The inter-roller vacuum passageway  146  allows for debris that is either picked up by (and/or removed from) the leading roller  124  to be entrained in the vacuum flow generated by the surface cleaning head  100  and/or to be picked up by the brush roll  122 , thereby enhancing the cleaning efficiency of the surface cleaning head  100 . Additionally, the distance L 1  reduces the load/drag on the motor(s), thereby enhancing the lifespan of the motor(s) and/or allowing smaller motors to be used to rotate both the brush roll  122  and the leading roller  124 . 
     One or both of the leading roller  124  and the brush roll  122  may be removable. The leading roller  124  may be removably coupled to the housing  110  of the surface cleaning head  100 . For example, a portion of the housing  110  (such as, but not limited to, a portion of the left and/or right side  116   a ,  116   b ) may be removably/hingedly coupled thereto. To remove the leading roller  124 , the removable portion may be unsecured/uncoupled from the rest of the housing  110 , thereby allowing the leading roller  124  to disengage from a drive wheel and allowing the leading roller  124  to be removed from the leading roller chamber  126 . Other ways of removably coupling the leading roller  124  within the housing  110  are also possible and within the scope of the present disclosure. 
     In some embodiments, the housing  110  of the surface cleaning head  100  may include a removable and/or hinged panel that allows the brush roll  122  to be removed. A shown in  FIGS.  1  and  8   , for example, the surface cleaning head  100  includes a panel  119  that may be removably and/or hingedly coupled to the housing  110 . To remove the brush roll  122 , the panel  119  may be disengaged from the housing  110  (e.g., removed) to allow the user to have access to a brush roll chamber  121 . Examples of removable panels or covers and removable brush rolls are described in greater detail in U.S. Pat. No. 9,456,723 and U.S. patent application Pub. No. 2016/0220082, which are fully incorporated herein by reference. Alternatively or additionally, the leading roller  124  may be removable in the same way. Another example of a removable leading roller is described in U.S. patent application Ser. No. 15/331,045, filed Oct. 21, 2016, which is incorporated herein by reference. 
     The ability to remove the brush roll  122  and/or the leading roller  124  from the surface cleaning head  100  allows the brush roll  122  and/or the leading roller  124  to be cleaned more easily and may allow the user to change the size of the brush roll  122  and/or the leading roller  124 , change type of bristles on the brush roll  122  and/or the leading roller  124 , and/or remove the brush roll  122  and/or the leading roller  124  entirely depending on the intended application. 
     In some embodiments, the surface cleaning head  100  may also include a series of combing protrusions  150  (also referred to as debriding protrusions) in contact with the leading roller  124 , as shown in greater detail in  FIGS.  4 - 7   . The combing protrusions  150  may be configured to remove debris (such as, but not limited to, hair, string, and the like) that may be wrapped around and/or entrapped/entrained in/on the leading roller  124  as the surface cleaning head  100  is being used (e.g., without the user having to manually remove the debris from the leading roller  124 ). According to one embodiment, the combing protrusions  150  may contact only the leading roller  124  (e.g., the combing protrusions  150  may not contact the brush roll  122 ). Some of the benefits of the combing protrusions  150  only contacting the leading roller  124  include increasing the lifespan of the leading roller  124 . Additionally, the combing protrusions  150  that only contact the leading roller  124  may reduce the load/drag on the motor, thereby allowing a smaller/less expensive motor to be used and making the surface cleaning head  100  lighter and less expensive to manufacture. 
     In this embodiment, the combing protrusions  150  may include a plurality of spaced ribs  152  with angled edges  153  extending into contact with a surface of the leading roller  124 . The spaced ribs  152  extend from a back support  151  with base portions  154  located therebetween to reinforce the spaced ribs  152 . The back support  151  may be mounted within the leading roller chamber  126 . The angled edges  153  of the spaced ribs  152  may be arranged at an angle A (see  FIGS.  4  and  6   ) that is in the range of 15-20 degrees, for example, 20-25 degrees, such as 23.5 degrees. This example structure of the combing protrusions  150  may allow for increased strength and reduced frictional loses since less points may contact the leading roller  124 . Other shapes and configurations for the combing protrusions are also within the scope of the present disclosure. 
     As shown in  FIGS.  4  and  5   , the combing protrusions  150  may be disposed at a height H above the bottom contacting surface  140  of the leading roller  124  and on a side or lower half of the leading roller  124 . The placement of the combing protrusions  150  may help to prevent the combing protrusions  150  from contacting a carpet, thereby reducing drag on the surface cleaning head  100  and reducing the likelihood of the combing protrusions  150  damaging the carpet. This arrangement also allows the combing protrusions  150  to be exposed to the inter-roller vacuum passageway  146 , thereby enhancing the removal of debris from the leading roller  124  by the combing protrusions  150 . The combing protrusion  150  may also substantially prevent air from flowing through the combing protrusions  150  to the inside upper portion (e.g., upper half) of the leading roller  124 . In other embodiments, a space may be formed between the outer surface of the leading roller  124  and the back support  151  such that air flows downward through the combing protrusions  150  to force debris into the air flow through the inter-roller vacuum passageway  146 . 
     As shown in  FIG.  7   , an embodiment of the surface cleaning head  100  optionally includes an electrostatic discharge element (ESD)  156 . The ESD  156  may reduce and/or prevent the buildup of electrostatic charge on the surface cleaning head  100 . The ESD  156  may include any known device for discharging electrostatic charge. According to one embodiment, the ESD  156  may include Barnet fibers woven between the openings in the back of the leading roller chamber  126 . The Barnet fibers may be arranged in close proximity to the combing protrusions  150  and/or leading roller  124  for discharging. For example, the ESD  156  may be connected to a printed circuit board assembly (PCBA) that dumps charge out to the neutral AC line. 
     In some embodiments, the housing  110  may further include a bumper  160  forming a top part of the front side  112  of the housing  110 , as shown in  FIGS.  1 ,  3 ,  5 , and  8   . The bumper  160  may reduce potential damage to either the surface cleaning head  100  and/or other objects in the environment. A front portion of the leading roller  124  is exposed at the front side  112  of the housing  110 , and the bumper  160  may extend around at least a top of the leading roller  124 . In the example embodiment, the bumper  160  includes a lateral portion  162  extending laterally along the front side  112  of the housing  110  and side portions  164 ,  168  extending downwardly along left and right sides of the front side  112  of the housing  110 . The side portions  164 ,  168  may extend to a point at or below the second rotation axis RA 2  of the leading roller  124 . 
     The bumper  160  may optionally define one or more front edge vacuum passageways  168 ,  169  providing at least a portion of the air flow path. As shown in  FIG.  4   , the bumper  160  may therefore generally form a seal with a vertical surface  12  (e.g., wall or the like) to improve front edge cleaning. The front edge vacuum passageways  168 ,  169  may allow for increased airspeed of the air being sucked into the surface cleaning head  100 , thereby enhancing front edge cleaning. The bumper  160  may also include one or more lateral air passageways disposed in the lateral portion  162 , which also allow for increased airflow along the front side  112 . 
     The bumper  160  may also include one or more compression elements  161 ,  163  (e.g., ribs) disposed on the lateral edge/section  162 . The compression elements  161 ,  163  allow for increased resiliency and cushioning of the bumper  160 . When the bumper  160  is pushed against the vertical surface  12  ( FIG.  4   ), the compression elements  161 ,  163  contact the surface  12  first and push the bumper  160  locally farther back than the rest of the bumper  160 , thereby forming a gap on either side of the compression elements  161 ,  163 . The gaps on either side of the compression elements  161 ,  163  form air paths allowing air to be drawn down in front of the leading roller  124 , which may disturb dust and debris so that it can be directed into the air flow path toward the suction conduit. 
     The bumper  160  may be formed as one piece with the housing  110  or may be formed as a separate piece secured within a groove and/or notch  165  formed between two or more pieces (e.g., an upper and lower portion  110   a ,  110   b ) of the housing  110 , as shown in  FIG.  3   . The groove and/or notch  165  may facilitate assembly of the housing  110  and the bumper  160  (e.g., between a headlight portion  110   a  and main portion  110   b  of the housing  110 ). 
     In some embodiments, the surface cleaning head  100  may further include one or more floor sealing strips  170 ,  172  and side edge vacuum passageways  174  on an underside of the housing  110 , as shown in  FIGS.  1  and  9   . The floor sealing strip(s)  170 ,  172  may include one or more sections extending outwardly from the housing  110  and having a length sufficient to at least partially contact the surface  10  to be cleaned. The floor seals strip(s)  170 ,  172  may include soft bristles, fabric material, rubber material, or other material capable of contacting the surface being cleaned to substantially prevent air flow into the opening  127  of the suction conduit  128  from the rear side. The sealing strips  170 ,  172  may also include a combination of elements or materials, such as bristles with a rubber strip extending along the strip between the bristles (e.g., with the bristles being longer than the rubber strip). 
     In the example embodiment, a lateral floor sealing strip  170  extends along a rear lateral portion (e.g., behind the opening  127  of the suction conduit  128 ) and side sealing strips  172  extend partially along the left and right sides  116   a ,  116   b . The side sealing strips  172  extend, for example, along a substantial portion of the opening  127  of the suction conduit  128  and are spaced from the leading roller  124  to define one or more side edge vacuum passageways  174  extending back towards the opening  127  of the suction conduit  128 . Because the leading roller  124  itself forms a seal with the surface  10  being cleaned, additional sealing strips are unnecessary along the front side  112 . Although separate strips  170 ,  172  are shown, one continuous sealing strip may be used. The floor sealing strips  170 ,  172  may enhance sealing between the surface cleaning head  100  and the floor  10 , thereby enhancing the vacuum efficiency. 
     The side edge vacuum passageways  174  may enhance the side edge cleaning efficiency of the surface cleaning head  100 . Side edge vacuum passageways  174  draw in air from the front  112  and the corner/sides  116   a ,  116   b  towards the suction conduit  128 , thereby enhancing edge cleaning as well as front cleaning. At least one of the side edge vacuum passageways  474  may also direct air into the inter-roller air passageway  146  between the leading roller  124  and the brush roll  122  to facilitate removal of debris from the leading roller  124 . As such, the side edge vacuum passageways  174  and the inter-roller air passageway  146  together provide at least a portion of the primary air flow path (e.g., as indicated by arrows  40 ) into the suction conduit  128 . 
     The side edge vacuum passageways  174  may be arranged at an approximately 45 degree angle with respect the longitudinal axis of the housing  110 . In other embodiments, the angle of the side edge vacuum passageways  174  may be within 30 to 60 degrees with respect the longitudinal axis of the housing  110 . Although the side edge passageways are shown as angled straight passageways, other shapes and configurations (e.g., S shaped or curved) are also possible and within the scope of the present disclosure. 
     Referring to  FIGS.  10 - 14 D , a combing unit  1050  used for cleaning a cleaning roller  1024  in a cleaning apparatus is described in greater detail. The cleaning roller  1024  may be rotatably mounted in a housing, such as the surface cleaning head housing described above, with the combing unit  1050  engaging the cleaning roller  1024 . The combing unit  1050  includes a series of spaced combing protrusions or teeth  1052  extending from a back support  1051  and extending partially into the cleaning roller  1024 . Although the illustrated embodiment shows the combing unit  1050  with teeth  1052  extending from a single back support  1051 , the combing unit  1050  may also include teeth extending from multiple back supports. 
     The combing unit  1050  may extend along a substantial portion of a length of the cleaning roller  1024  (i.e., more than half) such that the combing teeth  1052  remove debris from a substantial portion of the cleaning surface of the cleaning roller  1024 . In an embodiment, the combing teeth  1052  may engage the cleaning surface of the cleaning roller  1024  along, for example, greater than 90% of a length of the cleaning surface of the cleaning roller  1024 . The combing unit  1050  works particularly well with cleaning rollers that are designed to move hair and other similar debris away from a center of the roller  1024 . 
     The combing teeth  1052  have angled leading edges  1053  that are not aligned with a rotation center  1023  of the cleaning roller  1024 . The angled leading edges  1053  are the edges that an incoming portion of the rotating cleaning roller  1024  hits first and are directed toward or into a direction of rotation (i.e., into arrow  1002 ) of the cleaning roller  1020 . More specifically, the leading edge  1053  of a combing tooth  1052  forms an acute angle α relative to a line  1004  extending from an intersection point  1025  where the leading edge  1053  intersects with an outer surface of the cleaning roller  1024  to the rotation center  1023 . In some embodiments, the angle α is in a range of 5° to 50° and more specifically in a range of 20° to 30° and even more specifically about °24 to 25°. 
     In some embodiments, the combing teeth  1052  are positioned as close as possible to the bottom contact point  1040  of the cleaning roller  1024  but high enough to prevent being caught on a surface being cleaned (e.g., a carpet). The combing teeth  1052 , for example, may be positioned just above the lowest structure on the housing of a cleaning apparatus. Positioning the combing teeth  1052  closer to the bottom contact point  1040  of the cleaning roller  1024  allows debris to be intercepted and removed as soon as possible, thereby improving debris removal. 
     In another embodiment, shown in  FIG.  15 A , the combing unit  1050  may have other orientations and positions relative to the cleaning roller  1024  (e.g., above the rotation center  1023 ). In a robotic vacuum cleaner, for example, the combing unit  1050  may be positioned higher to prevent the combing teeth  1052  from interfering with the debris being deposited into a dust bin  1060 . 
     The combing teeth  1052  may extend into the cleaning roller  1024  to a depth in a range of 0% to 50% of the cleaning roller radius for a soft roller and 0% to 30% of the cleaning roller radius for a tufted brush roll. In one embodiment, the cleaning roller  1024  is a soft roller (e.g., nylon bristles with a diameter less than or equal to 0.15 mm and a length greater than 3 mm) and the combing teeth  1052  extend into the soft cleaning roller  1024  in a range of 15% to 35%. The combing protrusions  1052  may be positioned to provide a root gap or spacing between the back support  1051  and the outer surface of the cleaning roller  1024  such that air may flow between the cleaning roller  1024  and the back support  1051  and through the roots of the combing teeth  1052 . The air flow through the roots of the combing teeth  1052  may help to dislodge debris that has been removed from the cleaning roller  1024  and to direct the debris into an air flow passageway toward a suction conduit of a cleaning apparatus. The root gap may have a width RG in a range of 1 to 3 mm and more specifically a range of 2 to 3 mm. The root gap RG may extend across an entire length of the combing unit  1050 , or a root gap RG may be formed only in one or more sections along the length of the combing unit  1050  to form air channels only at those sections. In other embodiments, the back support  1051  of the combing unit  1050  may contact the outer surface of the cleaning roller  1024  to provide sealing and force air to flow under the cleaning roller  1024 . 
     In the illustrated embodiment ( FIGS.  11  and  14 D ), the combing teeth  1052  have a triangular-shaped “tooth” profile with a wider base or root  1054  having a root width W r  and a tip  1056  having a diameter D r . In general, the base or root  1054  may be wide enough to prevent the tooth  1052  from bending upward when contacted by the rotating cleaning roller  1024  and the tip  1056  may be sharp enough to catch the debris. In some embodiments, the tip  1056  may be rounded with a diameter in the range of less than 3 mm and more specifically in the range of 1 to 2 mm and even more specifically about 1.6 mm. The root width W r  may be in a range of 5 to 6 mm. 
     In another embodiment, shown in  FIG.  15 B , combing teeth  1052 ′ have a curved profile with curved leading edges  1053 ′ forming a concave curve. In this embodiment, a line  1006  extending from the curved leading edge  1053 ′ at the tip  1056  forms an angle α with the line  1004  extending from the intersection point  1025  to the rotation center  1023 . The combing teeth  1052 ′ with curved edges may be positioned and spaced similar to the teeth  1052  with straight leading edges  1053  as described and shown herein. 
     In some embodiments, the combing unit  1050  includes combing teeth  1052  spaced 4 to 16 teeth per inch and more specifically 7 to 9 teeth per inch. The combing teeth  1052  may be made of plastic or metal and may have a thickness that provides a desired rigidity to prevent bending when engaged with the rotating cleaning roller  1024 . In some embodiments, the combing teeth  1052  may have a thickness in a range of 0.5 to 2 mm depending upon the material. In one example, the combing teeth  1052  are made of plastic and have a thickness of 0.8 mm, a spacing S of about 2.4 mm, and a center-to-center spacing S c  of about 3.3 mm. 
     Although the combing unit  1050  is shown with combing teeth  1052  having an equal spacing, a combing unit  1050  may also include teeth  1052  with different spacings including, for example, groups of equally spaced teeth. The combing unit  1050  may include a section at the center of the cleaning roller  1024  with no teeth and groups of combing teeth  1052  proximate ends of the cleaning roller  1024  where the hair and similar debris migrates during rotation. Although the combing unit  1050  is shown with teeth  1052  having the same shape or tooth profile and dimensions, the combing unit  1050  may include teeth of different shapes, profiles dimensions and configurations at different locations along the combing unit  1050 . 
       FIGS.  16  and  17    illustrate examples of two different types of vacuum cleaners  1600 ,  1700  that may include a surface cleaning head  1602 ,  1702  with dual agitators including a leading roller  1624 ,  1724  and a combing unit (not shown), consistent with the embodiments described herein. The surface cleaning head  1602  with the leading roller  1624  may be used on an upright vacuum cleaner  1600  with a removable canister  1601  coupled to a wand  1604 , such as the type described in U.S. Patent Application Pub. No. 2015/0351596, which is commonly owned and fully incorporated herein by reference. The surface cleaning head  1702  with the leading roller  1724  may be used on a stick type vacuum cleaner  1700  with a removable handheld vacuum  1701  coupled at one end of a wand  1704 , such as the type described in U.S. Patent Application Pub. No. 2015/0135474, which is commonly owned and fully incorporated herein by reference. 
       FIG.  18    illustrates a robotic vacuum cleaner  1800  that includes a housing  1810  and a cleaning roller  1824  with a combing unit (not shown) as disclosed herein. The robotic vacuum cleaner  1800  may also include one or more wheels  1830  for moving about a surface to be cleaned. An example of the combing unit used in a robotic vacuum cleaner is disclosed in greater detail in U.S. Provisional Application No. 62/469,853, filed Mar. 10, 2017, which is incorporated herein by reference. 
     While the principles of the invention have been described herein, it is to be understood by those skilled in the art that this description is made only by way of example and not as a limitation as to the scope of the invention. Other embodiments are contemplated within the scope of the present invention in addition to the exemplary embodiments shown and described herein. Modifications and substitutions by one of ordinary skill in the art are considered to be within the scope of the present invention, which is not to be limited except by the following claims.