Patent Publication Number: US-8967688-B2

Title: Device and method for collection of material from a surface

Description:
This application is a U.S. National Phase of International Application No. PCT/GB2012/051855, filed on Jul. 31, 2012, which claims priority of GB1113298.2, filed on Aug. 2, 2011. The contents of the applications are incorporated herein by reference in their entirety. 
     The present invention concerns a device and method for collecting material from a surface, and a liner for use with such a device. 
     The present invention is particularly, although not exclusively, applicable to the collection of animal faeces. The problems involved are well known to dog owners. It is difficult to prevent dogs from defecating indiscriminately. In urban environments dog walkers are often required to collect their pets&#39; faeces and carry them to a suitable point of disposal. 
     To avoid direct contact with the faeces, it is a common practice to cover one hand with a plastic bag and grab the material, then pull the bag over the hand, turning it inside out in the process, so that the material is contained in the bag, whose open mouth can then be tied. The practice suffers from several drawbacks:
         a. feeling the warm faeces through the bag is distasteful to some;   b. the pet owner has to bend down to pick the waste up;   c. the collected material must be carried to a point of disposal, and often for the rest of the walk, in a bag which may not be completely sealed, leading to a risk of leakage; and   d. the bag may be broken or ruptured, e.g. by use on rough ground or while being carried. Contact of the faeces with the pet owner&#39;s fingers, clothing etc causes risk of exposure to serious pathogens.       

     There are existing devices for use in collecting animal faeces. One can of course use a shovel, dustpan and brush, pet vacuum cleaner etc. The problem with such tools is that their surfaces are exposed to the material being collected and so become contaminated, requiring subsequent cleaning, which again exposes users to pathogens in the faeces which can cause serious illness. There are also various “scoop” devices on the market. An example is sold under the trade mark Flexrake 33P and has an elongate handle with a pair of pivotally mounted, scoop-shaped jaws at one end. A push/pull rod running along the handle is connected at one end to a user-movable grip and at the other end to the jaws, so that by moving the grip the user can draw the jaws together around the material to be collected. No provision appears to be made for retention of the collected material, which would thus need to be subsequently deposited in a suitable container. Also it appears that the jaws of the device must become contaminated by the collected material. 
     Another device for collection of dog faeces is marketed by Poopsta of Lancashire, England, and comprises a hollow cylindrical housing with an open end which is to be covered by a plastic bag. An elastic band is placed around the housing and the bag to ready the device for use. The housing&#39;s open end is then placed upon the ground, over the animal waste, and depressed, causing the elastic band to slip off the housing and contract, sliding the open end of the bag under the waste and causing it to be captured in the bag, which can then be placed within the housing by the user. A removable lid is then used to close the housing. The device has the advantage that the only surface which contacts the animal faeces is the interior of the plastic bag. Shortcomings include the number of operations that the user must carry out during each use, involving removal of the lid, placing the plastic bag over the housing&#39;s open end, placing the elastic band around it, placing the device over the waste and depressing it, placing the bag and collected faeces in the housing, and replacing the lid. Also the operation requires the user to bend or stoop to place the housing in position on the ground. The number of times that the device can be used without being emptied is limited. 
     An object of the present invention is to provide an improved device for collection of material, particularly but not exclusively waste material and still more particularly animal faeces. It is particularly desired to provide a device capable of repeated and convenient use. It is also desired to provide a device for collection of material which is able to operate without becoming contaminated by the material being collected. 
     In accordance with a first aspect of the present invention, there is a device for collecting material from a surface, the device comprising a housing for receiving collected material, a jaw arrangement which is able to be opened to provide a mouth for receiving the material and closed to collect the material, and a conveyor mechanism for advancing a liner, placed over the jaw arrangement to separate it from the material being collected, into the mouth, along with material collected therein, whereby the material is able to be collected into the housing and retained in the liner without making contact with surfaces of the device. 
     The invention allows the jaws, which would otherwise become contaminated by the collected material, to be covered by the liner. The collected material can be contained by the liner and moved into the housing for transport/storage/disposal without any need for the user to handle it and without contaminating any internal parts of the device. 
     It is especially preferred that the conveyor mechanism is operable when the jaw mechanism is closed. In this way the jaws can be closed around the collected material and then, in a separate and subsequent action, the conveyor can be operated to advance the liner and the collected material into the housing. 
     It is also preferred that the jaw mechanism and the conveyor mechanism are independently operable, so that the jaw mechanism is able to be opened and closed without advancing the liner. In this way the user can if need be try more than once to close the jaws around the material in order to collect it, before actuating the conveyor to move the material into the housing. 
     According to a second aspect of the present invention there is a liner for use with a collection device, the liner comprising an elongate tube of flexible material which is crushed, concertinaed or otherwise compacted to form a frame with an opening, allowing the frame to be placed around a part of the collection device for mounting. 
     The “frame” in question may for example be circular or square. It may be supported by some form of frame member additional to the liner itself, but this is not required. 
     In one embodiment the liner has, at intervals along its length, sealing strips able to form a seal across the liner when pressed against themselves. The sealing strips may be self adhesive strips or zips. 
    
    
     
       Specific embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
         FIGS. 1   a  to  1   e  are simplified perspective illustrations of a first collection device embodying the present invention at successive points in its operation; 
         FIGS. 2   a  to  2   c  are sections through the same collection device taken in a vertical plane and again showing successive stages in the devices&#39; operation; 
         FIG. 3  is an exploded view of an internal sliding casing of the same device and includes various working parts carried by the sliding casing; 
         FIG. 4  is an exploded view of an outer housing of the same device and includes various working parts carried by the housing; 
         FIG. 5  is a perspective view of part of the device&#39;s housing and associated component; 
         FIG. 6  is similar to  FIG. 5  but shows a handle and related parts in a different position; 
         FIGS. 7   a  and  7   b  are simplified perspective views of the device showing how it can be opened to eject collected material; 
         FIG. 8  shows a liner for use with the device; 
         FIG. 9  is a simplified sectional view through the device in a vertical plane, showing details of a latch mechanism; 
         FIGS. 10   a  to  10   c  represent the latch mechanism on its own and show successive stages in its operation; 
         FIG. 11  is a perspective illustration of a modified version of the first collection device; 
         FIG. 12  shows some internal components of a second collection device embodying the present invention, viewed from a first side; 
         FIG. 13  is an enlarged view of a resilient linkage used in the second collection device; 
         FIG. 14  is similar to  FIG. 12  but shows the device&#39;s internal components from a second side, opposite the first; 
         FIG. 15  shows the same internal components as  FIGS. 12 and 14 , viewed from the front of the device; 
         FIG. 16  is a perspective illustration of a former for carrying a liner for use in a collection device embodying the present invention, the liner itself being omitted; 
         FIG. 17  is similar to  FIG. 16  but additionally includes the liner, showing it opened out to reveal its shape; 
         FIG. 18  is a perspective illustration of the former, the liner, this time in a compact, pre-use configuration, and of a portion of a housing of a collection device which is adapted to receive the liner; 
         FIG. 19  is a perspective illustration of a third collection device embodying the present invention; 
         FIG. 20  shows a lower part of the third collection device viewed from one side and partly in section; and 
         FIG. 21  shows the third collection device viewed from above, parts of the device being cut away to reveal details of its interior. 
     
    
    
     The collection devices illustrated in the drawings are all intended for collection and carrying of animal faeces. In particular they are usable by dog walkers to collect dog faeces from the ground and allow them to be safely transported to a bin or other waste disposal facility. Such devices are colloquially referred to as “poop scoops”. Note however that the present invention has potential applications in other fields, as will be explained below. 
       FIGS. 1   a  to  1   e  illustrate some major components of a first collection device  10  embodying the present invention and show the sequence of steps in the device&#39;s operation. In  FIG. 1   a  the device  10  is configured for carrying. It can be seen to comprise a housing  12 , which in the present embodiment is generally cuboidal and is spilt along a line  14  into two separable parts. Other shapes and configurations of the housing are possible. The device can be provided with some form of strap or other means to facilitate carrying and in the present embodiment this takes the form of a shoulder strap  16 . The device has an extensible handle  18  whose end only is seen in  FIG. 1   a , the remainder of the handle being contained in the housing  12  so that the device forms a relatively compact shape which can be conveniently carried. 
     To ready the device  10  for use ( FIG. 1   b ) the extensible handle  18  is drawn out of the housing  12 . The user can hold the device at upper end  20  of the handle  18  and because the handle is elongated it is not necessary for the user to stoop or bend to collect waste material from the ground. Also seen in  FIG. 1   b  is a jaw arrangement  22 . When the device is configured for carrying ( FIG. 1   a ) the jaw arrangement  22  is contained within the housing  12 . The action of withdrawing the handle  18  causes the jaw arrangement  22  to be advanced downwardly out of the housing  12 , and also to be opened ready for use in collecting waste material. In the illustrated embodiment the jaw arrangement comprises a pair of jaws  24   a ,  24   b  which are each pivotally mounted. The axis about which jaw  24   a  pivots is indicated at  26  in  FIG. 1   b . Other jaw configurations could be adopted. For example the arrangement could use a single movable jaw arranged to cooperate with a fixed jaw to collect waste material. The term “jaw” in this context refers to any part shaped and arranged to scoop or otherwise collect the waste material from the ground surface. In the jaws&#39; open configuration they form a mouth  28  for receiving the waste material. The user places the device over the material to be collected (which is not shown in  FIG. 1 ) with the material in the mouth  28 . Lower edges of the jaws  24   a ,  24   b  are preferably in contact with the ground surface at this point. 
     A user-operable actuating part is provided to enable the user to close the jaws. In the illustrated embodiment this takes the form of a user-operable lever  30  toward the upper end of extensible handle  18 . The lever  30  is automatically deployed when the handle  18  is extended from the housing  12 . To this end, in the illustrated embodiment, the lever  30  is sprung toward an open position ( FIG. 1   b ). Gripping the lever  30  causes the jaw arrangement  22  to close, as seen in  FIG. 1   c , collecting the waste material between the jaws. 
     Once the material has been collected into the jaws in this manner, the user can cause the material to be advanced into the housing for storage. In the illustrated embodiment the action of pushing the handle  18  into its stowed position within the housing  12  causes the jaw arrangement  22  to retract into the housing and at the same time, in a manner to be explained below, advances the waste material into the housing  12 . A hinged flap  32  closes the otherwise open lower end of the housing  12  when the jaw arrangement  22  is retracted—see  FIG. 1   d . After use the device  10  is returned to its carrying configuration— FIG. 1   e.    
     An important aspect of the device not seen in  FIG. 1  relates to its use of a liner  33  to cover the jaw arrangement and so separate it from the material being collected, so that contamination by the waste material is limited to the liner, with no surfaces of the device  10  itself needing to be brought into contact with the waste material being collected. This aspect, and the details of the device&#39;s internal mechanism, will now be explained with particular references to  FIGS. 2 to 6 . 
     The liner  33  can be seen for example in  FIGS. 2   a  to  2   c . In the present embodiment the liner  33  is formed as an elongate tube. It comprises flexible and preferably impermeable sheet material. In the illustrated embodiment the material is thin plastics akin to the material of a plastic bag. Polyethylene film is one suitable material although there are many others. The liner  33  is passed around and over the jaw arrangement  22 , back through the jaw arrangement&#39;s mouth  28  and so into the interior of the housing  12 . The above-mentioned step of advancing the collected waste material into the housing  12  involves advancing the liner  33 , with the waste material contained in it, into the housing. The liner  33  thus contains the waste material within the housing  12 , preventing the material from contaminating the device&#39;s interior. 
     Looking at  FIG. 2  in more detail, it can be seen that the device comprises a sliding assembly mounted in the housing  12  and incorporating the jaw arrangement  22 . In the illustrated embodiment this sliding assembly comprises a sliding casing  34  which is movable up and down within the housing  12  to advance/retract the jaw arrangement  22 . Details of the sliding assembly are illustrated in  FIG. 3 . The sliding casing  34  is a box-like hollow structure formed in two parts which are separated from one another in FIG.  3  and designated  34   a  and  34   b  in that drawing. Runners  36   b  formed on second part  34   b  of the sliding casing have a dovetailed or otherwise undercut cross section. Complementarily formed guideways  38  are provided upon a second part  12   a  of the housing  12  (see  FIG. 4 ) to receive the runners  36   b  and so slidably mount the second casing part to the second housing part. The first casing part  34   a  is attached to the second casing part  34   b  through a hinge  37  ( FIG. 3 ) and is loosely tethered to the first housing part  12   a  so that when the housing  12  is opened, the sliding casing  34  opens along with it. When the housing  12  is closed for use, the two casing parts  34   a ,  34   b  mechanically engage with one another and so move as a unit. 
     Each of the casing parts  34   a ,  34   b  carries one of the jaws  24   a ,  24   b . In  FIG. 3  it can be seen that each of the jaws  24   a ,  24   b  comprises a lower casing portion  40   a ,  40   b  pivotally attached to the remainder of its respective casing part  34   a ,  34   b  through a respective hinge  42   a ,  42   b.    
     Advancement of the liner  33 , and of the collected material, into the housing  12  is managed by means of a set of conveyors formed in the present embodiment as belts  44 ,  46 . The relevant components carried by the first casing part  34   a  will now be described. Components carried by the first casing part  34   a  are denoted, in the following paragraphs, by the suffix “a.” It is to be understood however that the second casing part  34   b  has a similar arrangement of belts and associated parts and in the drawings these are denoted by the suffix “b”. 
     The first casing part  34   a  carries a pair of belts  44   a ,  46   a  which are laterally separated from one another. The belts are carried upon lower and upper axle assemblies  48   a ,  50   a  (the terms “upper” and “lower” refer herein to the orientation of the device in which it is seen in  FIG. 1 , with the jaws lowermost). The lower axle assembly  48   a  is carried by the first jaw  24   a  toward its lower end. The lower axle assembly  48   a  carries a pair of pinions  52   a ,  54   a  upon which the respective belts  44   a ,  46   a  are mounted and the belts are internally toothed to engage with the pinions, providing positive drive without slip, so that the device&#39;s four belts move in step with one another. The upper axle assembly  50   a  is mounted by and within the sliding casing  34 , at or at least toward its upper end, and carries a further pair of pinions  56   a ,  58   a  upon which the respective belts  44   a ,  46   a  are mounted. To maintain belt tension as the jaws are opened and closed, the upper axle assembly  50   a  is movable and is acted upon by tension springs  60   a  (see  FIG. 2 ). Comparing  FIGS. 2   a  and  2   b  it can be seen that these springs are extended when the jaw  24   a  is in its open position ( FIG. 2   a ) and contract, drawing the upper axle assembly  50   a  upwards to maintain belt tension, when the jaw moves to its closed position ( FIG. 2   b ). Guides  62   a  formed within the sliding housing  34  constrain the paths taken by the belts  44 ,  46  in the vicinity of the hinges  42  and prevent the belts from rubbing on other parts of the device when the jaws  24   a ,  24   b  are opened (see  FIG. 2   a  in particular). 
     The two belts  44   a ,  46   a  carried by the first casing part  34   a  are linked to one another by a set of collecting paddles  64   a . The term “paddles” as used herein does not in itself imply any particular shape for these components, which could take any of a number of different forms commensurate with their function. In the illustrated embodiment they are formed as elongate slender panels standing up from the belts&#39; outer faces. 
     As noted above, the second casing part  34   b  carries its own arrangement of second belts  44   b ,  46   b ; second upper and lower axle assemblies  48   b ,  50   b ; second pinions  52 - 58   b ; second tension springs  60   b  and second guides  62   b , all of them similarly formed to the corresponding parts carried by the first casing part  34   a.    
     A mechanism is provided for advancing the two sets of belts  44   a ,  46   a  and  44   b ,  46   b  together. In the illustrated embodiment, this is achieved by means of a rack and pinion drive whose rack  66  is carried by, and within, the housing  12  and meshes with a pinion  67  mounted on the second upper axle assembly  50   b  to drive it, and so drive the second belts  44   b ,  46   b . To transfer drive to the first belts  44   a ,  46   a , the second upper axle  50   b  carries, on the side of the casing  34  opposite the rack and pinion drive, a transfer gear  66   b  which meshes with an identical transfer gear  68   a  carried by the first upper axle assembly  50   a  (see  FIG. 3  in particular). A ratchet mechanism  47  (see  FIG. 3 ) ensures that the axle assemblies  50   a ,  50   b , and the belts  44   a ,  46   a ,  44   b ,  46   b  that they carry, can turn only in one direction. In  FIG. 2   b , the first upper axle assembly  50   a  is able only to turn clockwise and the second upper axle assembly  50   b  only anticlockwise, causing the liner  33  to advance into the housing  12 . 
     The manner in which collected waste material is advanced into the housing  12  can now be understood, referring once more to  FIGS. 2   a  to  2   c . After the jaw arrangement  22  has been closed ( FIG. 2   b ), the sliding casing  34  is withdrawn into the housing  12 . This motion of the casing  34  causes the axle assemblies  48 ,  60  to turn, advancing the belts  44 ,  46 . At the beginning of this motion, a pair of first and second paddles  64   a ,  64   b  lie opposite and adjacent one another and at lower ends of their respective jaws  24   a ,  24   b . These paddles collect and contain the waste material, which is item  70  in  FIG. 2 . As the belts advance, the waste material and the liner  33  around it are moved, by the action of the paddles  64   a ,  64   b , into the device&#39;s interior. Note that by virtue of the lateral separation of the pairs of belts  44 ,  46  (seen in  FIG. 3 ), the waste material is not squeezed between the belts but instead is allowed to occupy as much of the volume within the sliding casing  34  as it requires, causing the liner  33  to correspondingly bulge, as seen at  72  in  FIG. 2   c , whilst at the same time being retained between pairs of paddles  64   a ,  64   b  above and below. 
     A mechanism is provided to move the sliding casing  34  between the retracted position of  FIG. 2   c  and the advanced position of  FIGS. 2   a  and  2   b . This mechanism can best be seen in  FIG. 4 . As noted above, in the illustrated embodiment it is the act of extending/retracting the handle  18  that causes the sliding casing  34  and the jaw arrangement  22  to advance/retract. However the distance through which the handle  18  moves is larger than the distance through which the sliding casing  34  moves. One solution to this problem would be to have the handle  18  engage with the casing  34  for only a short part of its stroke. However a more elegant solution, providing the user with mechanical advantage in the actuation of the mechanism, is found in the present embodiment. A pair of actuating levers  76 ,  78  is carried upon the second housing part  12   b . Each lever pivots about a respective fulcrum  80 ,  82  which is fixed with respect to the housing  12 . Each has a respective slot  84 ,  86  running along its length. The handle  18  carries an actuating pin  88  which is received in both slots  84 ,  86  as a sliding fit. On the opposite side of the fulcrum  80 ,  82  from the actuating pin  88 , each actuating lever  76 ,  78  has a respective engagement pin  90 ,  92  which projects into a corresponding lateral slot  79  formed in the sliding casing  34  (see  FIG. 3 ). 
     Moving the handle  18  causes the actuating levers  76 ,  78  to turn and so causes the sliding casing  34  to move up/down. Note that the mechanism provides a reverse: of direction—when the handle  18  is moved downward, to retract it, the sliding casing  34  moves upward, to correspondingly retract the jaw arrangement  22 . Also because a distance between the fulcrum  76  or  78  and the actuating pin  88  is longer than the distance between the fulcrum  76  or  78  and the respective engagement pin  90 ,  92  the mechanism provides the required mechanical advantage—that is, the handle  18  moves through a longer stroke than the sliding casing  34 . 
     The handle  18  is coupled to the housing  12  in a manner which provides for its extending/retracting motion. In the illustrated embodiment the handle  18  terminates in a carriage plate  94  slidably mounted between two rails  96  formed within the housing  12 . 
     A user-operable mechanism is provided for closing the jaw arrangement  22 . Note in this regard that the user is able to control movement of the jaw arrangement independently of the advancement and retraction of the jaws so that if need be the user can make more than one attempt at closing the jaws around the waste material, before completing the process by retracting the jaws and thereby moving the collected material into the housing  12 . Each of the jaws  24   a ,  24   b  is controlled through a respective pair of jaw actuating rods  100   a ,  100   b . One of each pair can be seen in  FIG. 3 , being mounted on a side face of the sliding casing  34 . The other member of each pair is on the opposite side of the sliding casing  34  and so not seen in the drawing. Each jaw actuating rod  100   a ,  100   b  couples to a respective hinged casing portion  40   a ,  40   b  through a respective pivot  102   a ,  102   b  which is laterally offset from the corresponding hinges  42   a ,  42   b  so that by moving the jaw actuating rods  100   a ,  100   b  the jaws  24   a ,  24   b  can be opened and closed. 
     The jaw actuating rods  100   a ,  100   b  are coupled, through slots in side was of the sliding casing  34 , to “L” shaped coupling parts  104 ,  106  seen in  FIGS. 4 to 6  and arranged outside and on opposite sides of the sliding casing  34 .  FIG. 5  shows pivot rods  108 ,  110  which pivotally engage with the jaw actuating rods  100 . The two coupling parts  104 ,  106  are linked by a cross member  112  so that they move together to open and close the jaws. The pivot rods  108 ,  110  are received in slots  107  (see  FIG. 3 ) which provides freedom for the jaw assembly to be retracted. 
     As explained above, the user closes the jaws by means of a lever  30  which is near the upper end of the extensible handle  18 . To this end, the handle  18  is hollow and contains, as seen in  FIG. 4 , a pair of coupling levers  114 ,  116  to convert rotational motion of the lever  30  to linear movement of a coupling rod  118  which extends through the handle  18 , emerging into the outer housing  12  at the handle&#39;s lower end to meet a T bar  120  which is carried beneath the carriage plate  94  through mushroom shaped buttons  122 ,  124 . The buttons slide captively in short slots  125  in the carriage plate  94  to allow the T bar  120  to more relative to the carriage plate  94 . 
     When the user squeezes the lever  30 , the coupling rod  118  is drawn upwardly. This motion is transmitted through the T bar  120 , abutting the cross member  112 , to the coupling parts  104 ,  106  and so to the jaw actuating rods  100   a ,  100   b  and to the jaws  24   a ,  24   b , causing them to close. 
     Note that because the T bar  120  is not coupled to the cross member  112 , the mechanism does not hinder retraction of the handle  18  into the housing  12 . As seen in  FIG. 6 , retraction simply causes these parts to move away from one another. The mechanism can thus urge the jaws to close but cannot cause them to open. Opening of the jaws is caused by a spring arrangement which is not seen in the figures but may for example comprise torsion springs acting on the casing portions  40   a ,  40   b.    
     The collection device can be used multiple times before it requires emptying. That is, the user can repeat the sequence of steps explained with reference to  FIG. 1  twice or more. When the user reaches a suitable waste disposal point, however, the device needs to be emptied.  FIGS. 7   a  and  7   b  show one way that this can be done. The housing  12  is formed in two separable parts, as noted above. In the present embodiment these are coupled along their top edges through a housing hinge  128 . Opening the housing  12  about the hinge separates the two parts of the sliding casing  34 , allowing the collected material, carried in the liner  33 , to fall or be removed from the device ( FIG. 7   b ). 
     For the convenience of the user, the present embodiment incorporates a release button  130  used to open the housing  12 . In  FIG. 4  it can be seen that the release button is mounted in a first part  12   a  of the housing  12 , in an upper wall thereof, and is coupled through a release bar  132 , which is upwardly biased by a spring  134  and extends around the inner periphery of the housing  12 , to a pair of bolts  136  on opposite sides of the device. When the user closes the housing  12  by pushing its two parts together, the bolt  136  first rides along an inclined face  138  of a catch  140  formed on second part  12   b  of the casing, then snaps into an undercut inner face  142  of the catch  140  to secure the casing parts  12   a ,  12   b  together. Depressing the release button  130  causes the bolt  136  to slide downwards, disengaging it from the catch  140  and allowing the housing  12  to open. 
     Looking at  FIG. 2  it will be recognised that the paddles  64   a ,  64   b  carried on opposite parts of the sliding casing  34  need to be aligned in pairs to perform their function. While the housing  12  and the sliding casing  34  are closed, meshing of the drive gear  68  and the driven gear ensures that the paddles advance in step and remain properly aligned. However when the sliding casing  34  is opened these gears are separated and there is the possibility that one will turn relative to the other, taking the paddles out of alignment. To prevent this from happening, a latch mechanism locks the gears when the sliding casing  34  is opened.  FIG. 3  shows the details. The upper axle assemblies  50   a, b  each carry a latching gear  144   a, b  associated with a respective locking bar  146   a, b  which is biased toward engagement with its latching gear to prevent rotation. Pushrods  148   a, b  are arranged to disengage the locking bars when the sliding casing  34  is closed. When the sliding casing  34  is opened, the pushrods are released, the locking bars engage and rotation of the gear mechanism is prevented. 
     Consideration also needs to be given to the manner in which the liner  33  is inserted into the collection device to prepare it for use. The liner  33  may be provided to the user in the form seen in  FIG. 8 . A length of tubular liner material sufficient for multiple uses is collapsed into a small volume in the manner of a concertina and is carried on a rectangular frame, making it easy to insert the concertinaed lining into the device, around the sliding casing  34 . To install the liner  33  ready for use, the end of the liner is pulled downward around the extended and open jaw arrangement  22  and is then fed back into the jaw&#39;s open mouth  28 . At this point the liner  33  needs to be gripped by the paddles  64  to enable it to be advanced into the collection device. To this end, the device comprises a jaw latch mechanism so that the jaws can be pushed closed by hand, gripping the liner  33 , and kept closed while the mechanism is advanced. The latch mechanism automatically releases when the jaws are retracted.  FIGS. 9 and 10   a - 10   c  show a suitable jaw latch mechanism comprising a hook  150  pivotally mounted on one of the jaws  24   a  and arranged to be engageable with a latch pin  152  on the other of the jaws  24   b  tri latch them closed. The hook  150  is coupled to a latch rod  154  which is mounted to the sliding casing  34  in a manner which permits it to move longitudinally, its upper end being elbowed to form a laterally projecting spring arm  156 . A peg  157  is provided on an inner face of the housing  12  and arranged to engage the spring arm  156 . Initially, following manual closing of the jaw arrangement  22 , the spring arm  156  lies beneath the peg  157  ( FIG. 10   a ) and maintains the hook  150  in its “latched” position. However as the sliding casing  34  is retracted into the housing  12 , the spring arm is forced past the peg  157 , releasing the latch mechanism so that the jaws can be subsequently be opened for use. 
     The liner  33  may be blind-ended. That is, the end of the liner  33  for insertion into the mouth  28  is closed. Also this end of the liner may be provided with a grippable feature  159  with which the paddles can engage to entrain the liner  33 . 
     It is desirable to minimise external dimensions of the device to make it as convenient as possible for carrying. To this end the paddles  64  may be formed in a manner which allows them to “feather” on their return path, lying against the belts  44 ,  46  on which they are carried and so minimising the volume within the device that needs to be provided for them.  FIG. 3  omits most of the paddles  64  themselves, showing only pads  158  on which the paddles are to be mounted, but shows an internal guide plate  160  which causes the paddles  64 , which may be formed of resilient material or could for example be mounted on the pads  158  through pivots, to lie down against the belts as they pass inclined guide surfaces  162 . 
     It is desirable to prevent any material from escaping once it has been collected into the liner  33 . In some embodiments the paddles  64  alone serve to retain the collected material. However means may be provided for forming a seal across the liner beneath the collected material. In one such embodiment (not illustrated) self adhesive strips are provided at intervals across the interior of the liner  33  and are positioned to be pressed together by the paddles  64  to form the desired seal. An alternative is to provide the collection device with means for heat sealing the liner  33  after it has been advanced. Another alternative is to use zips, e.g. of the moulded plastics variety, at intervals along the liner to close it. 
     Heat sealing may be achieved by providing the paddles  64  with heating elements on their outer edges. In this case the paddles may be arranged in parallel pairs closely spaced along the directions of travel of the belts on which they are carried, so that the leading paddle of a pair will serve to contain the collected material. The other paddle of the pair is provided with the heating element and follows the first. In this way the heating element is prevented from coming into close contact with the collected material. 
     While the above described embodiments provide for the housing to be opened to eject collected material, another possibility is to have the collected material fed out of the device.  FIG. 11  illustrates the principle. The liner  33  is able to emerge through the top of the housing  12 . The internal mechanism may for example be able to freewheel to allow the liner to be pulled through, or alternatively, repeated actuation of the mechanism may serve to eject the liner and the material collected in it. 
     The collection device  210  illustrated in  FIGS. 12 to 15  differs from the above described collection device  10  in that certain parts of its mechanism are power operated rather than being manually operated. More specifically, the collection device  210  uses electric motors to drive (a) the opening and closing movement of the jaws and (b) advancement of the conveyor mechanism to draw collected material into the device. These two functions are independently power driven and, as will be explained further below, the sequence of operations can, in a motor driven version, be electronically controlled. 
     Details of the mechanism for driving opening and closing of the jaws are best seen in  FIG. 12 . This drawing shows a sliding casing  234  similar to the sliding casing  34  of the earlier described embodiment, and once more comprising hingedly coupled first and second casing parts  234   a ,  234   b . Pivotally coupled to each casing part  234   a ,  234   b  is a respective jaw  224   a ,  224   b . The conveyor mechanism of the second collection device  210  is not seen in the drawings but may be similar to that of the first collection device  10 . 
     Also omitted from  FIGS. 12 to 15  are (a) the external housing, item  12  in the drawings of the first collection device and (b) the mechanism that moves the sliding casing  234  within the housing to advance/retract the jaws. Again, these aspects of the second device  210  can match the corresponding features of the first device  10 . In particular, advancement and retraction of the jaws and the sliding casing can be carried out using the manual lever arrangement and retractable handle of  FIG. 4 , although in other embodiments that function could also be motorised. 
     An electric motor  300  drives the jaws  224   a ,  224   b . The motor is supplied with electric power by one or more batteries carried in the device&#39;s housing, but the adaptation of the housing to receive the batteries is conventional and is not shown in the drawings. Leading from the motor to each of the jaws  224   a ,  224   b  is a respective drive mechanism comprising a speed reducing gear train, to amplify the modest torque available from the motor  300 , and a crank and pushrod arrangement leading to the jaws  224   a ,  224   b . The gear trains use a worm  302  carried on a shaft  304  of the electric motor  300  to drive a toothed worm wheel  306 . A pinion  307  which is coaxial with the worm wheel  306  and mounted to rotate along with it drives first and second crank gears  308   a ,  308   b  carried by respective casing parts  234   a ,  234   b.    
     The first crank gear  308   a  carried by the first casing part  234   a  serves as a crank by virtue of a pivotal coupling  310   a  to a first pushrod  312   a . The pushrod has a further pivotal coupling  314   a  to the first jaw  224   a , this coupling being offset from pivot  316   a  by which the jaw is mounted. When the motor shaft  304  turns, the first crank gear  308   a  turns along with it and drives the first pushrod  312   a  reciprocally to move the first jaw  224   a  between its closed and open positions. 
     Gearing carried by the second casing part  234   b  differs from that carried by first casing part  234   a  only in that it additionally incorporates a reversing gear  313  between second crank gear  308   b  and pinion  307 . This is needed in order that the first and second crank gears  308   a ,  308   b  rotate in opposite directions. A second pushrod  312   b  couples the second crank gear  308   b  to the second jaw  224   b  to move it between its closed and open positions, and of course the gearing is arranged such that the jaws  224   a ,  224   b  open and close in unison. 
     The pushrods  312   a ,  312   b  incorporate respective resilient couplings  320   a, b  which serve to protect the jaw drive mechanism from damage. If for some reason excessive force is applied to the jaws  224   a,b , tending to open or close them, the resilient couplings  320   a, b  allow the jaws to move independently of their drive mechanisms, to avoid overloading them.  FIG. 13  shows one of the resilient couplings  320 , which in this particular embodiment uses a pair of pre-stressed helical springs acting in opposition to one another. The pushrod  312  is broken into two parts  322 ,  324 . A peg  326  carried by one pushrod part  322  projects through a slot  328  (see  FIG. 12 ) in the other pushrod part  324 . The two springs  330 ,  332  each couple to the peg  326  and extend from it in opposite directions to respective further pegs  334 ,  336  carried by the other pushrod part  324 . If force on the pushrod  312 , in either direction along its length, exceeds the force with which the springs  330 ,  332  are pre-stressed then the pushrod  312  yields, its length changing as its two parts slide relative to one another, allowing the corresponding jaw  224   a  or  b  to move. Clearly the required resilience could be incorporated into the drive mechanism in numerous other ways. 
     In the present embodiment the jaws  224   a,b  are hinged about shafts  316   a, b  which coincide with centre lines of the respective conveyor belts  364   a,b , which can just be seen in  FIG. 14 , so that the length of the conveyor&#39;s path does not change significantly as the jaws  224   a,b  move. Consequently tensioning springs  60   a, b  of the first embodiment can be dispensed with. 
     The mechanism for driving the conveyor is seen in  FIG. 14  and comprises a second electric motor  350  whose shaft  352  carries a worm  354  for driving a worm wheel  356  and a pinion  358  coaxial with the worm wheel. The first casing part  234   a  has a first conveyor drive gear  360   a  which meshes with the pinion  358  and which is mounted on a first conveyor shaft  362   a  which drives a first conveyor arrangement one of whose belts can be seen at  364   a  in the drawing. The gear train leading to second conveyor shaft  362   b  carried by the second casing part  234   b  is different in that it includes a reversing gear  366 , in order that conveyor shafts  362   a,b  rotate in opposite directions. 
     In the first described collection device  10 , a latch mechanism is provided to lock the conveyor mechanisms when the user opens the sliding casing  34 , to prevent the respective conveyor mechanisms carried by the casing parts  34   a ,  34   b  from becoming misaligned with one another. The second collection device  210  does not require any such latching mechanism because as its casing  234  is opened the gear trains for driving the jaws and the conveyors do not disengage. Looking again at  FIG. 12 , for example, the axis of the pinion  307  coincides with the axis of a hinge coupling the two casing parts  234   a, b . As the casing parts pivot about this axis relative to one another, the first crank gear  308   a  and the reversing gear  313  describe circular arcs about the axis, and so stay in mesh with the pinion  307 .  FIG. 15  shows that the pinion  307  and the pinion  358  are carried on the same shaft  366  that serves as the hinge coupling the two casing parts  234   a, b , although to allow the two pinions to rotate independently the shaft is formed in two concentric parts  368 ,  370 , one being received in the other. 
     The motorised mechanisms are controlled by user-operable switches (not shown) carried on the handle, which may, in the present embodiment, be generally similar in construction to the handle  18  of the first embodiment. A jaw control switch can be moved by the user between forward, reverse and off positions, running the jaw actuating motor  300  in one direction to open the jaws and in the opposite direction to close them. Limit switches or sensors of other type (not shown) are provided to detect when the limit of the jaws&#39; travel in either direction has been reached, and to turn off the motor  300  in response. The limit switches may engage with the gearing or with the jaws  224   a, b.    
     A user-operable conveyor switch (not shown) is carried by the handle and is actuable by the user to activate the conveyor motor  350 . 
     A logic circuit is provided, receiving signals from sensors/switches, to ensure that operations are carried out in appropriate sequence, for example by (a) detecting when a pair of paddles are positioned adjacent each other at the bottom of the jaws  224   a,b , ready to collect the next load of waste material, and stopping the conveyor motor  350  in response; (b) detecting when a bag is inserted; (c) detecting whether the jaws are retracted and preventing the jaw actuating motor  300  from running when they are etc. The logic circuit may comprise discrete electronic components, a suitable arrangement of switches, and/or programmed microprocessor. Its design would be straightforward for the skilled person and details are not provided herein. 
     The collection device  210  uses a rack and pinion arrangement (not shown) to drive advancement and retraction of the jaws, as in the earlier embodiment, but an alternative is to motorise that function as well. For example a switch or sensor may be provided to detect when the handle is collapsed and to retract the jaws in response. 
       FIGS. 16 to 18  show alternative means for packaging and for installing the liner used to prevent the components of the device from contacting the material being collected. A frame  400  carries the liner  402 .  FIG. 16  shows the frame on its own and in the present embodiment it comprises flat sheet material forming a rectangular shape with an opening  404  and a pull tab  406 . The preferred material for the frame  400  is cardboard but plastics sheet or other suitable materials may be used. As supplied to a user, the liner  402  is carried upon the frame in a compact state, being concertinaed or otherwise crushed to lie adjacent the frame ( FIG. 18 ). The liner&#39;s mouth is attached to the frame  400 , surrounding the opening  404 , as can be appreciated from  FIG. 17 . This attachment can be formed by bonding. Housing  412  has a slot  410  in one of its side faces, into which the frame and liner  400 , 402  in the compact state can be inserted, and the housing has internal features (not seen) such as rails to receive and locate the frame  400 . A waisted portion  411  of the pull tab  406  clips into a recess  413  in the periphery of the slot  410  to keep the frame and liner in place. A hinged sealed cover (not shown) can trap the pull tab  406  and close the slot  410  to seal any odours in the housing. To insert the frame and liner  400 , 402  into the housing  412 , the jaws  24   a ,  24   b  or  224   a ,  224   b  must be retracted, in which state they lie above the frame  400 . When the jaws are advanced, they move through the opening  404  in the frame  400 , drawing the liner  402  with them so that the jaws are covered by the liner  402 . The liner needs to pass back into the mouth  28  formed by the jaws  24   a, b ,  224   a, b  to enable it to be drawn into the device by the conveyors (refer again for example to  FIG. 2   a , which shows the liner  33  in a suitable configuration) but this can be easily achieved either by having the user push the liner into the mouth  28 , or simply by the effect of the material  70  being collected (see  FIG. 2   a  again) which presses the liner into the mouth  28 . Note that in the present embodiment the liner  402  is formed in the manner of a bag, having a closed end  414 . A liner of this type may be formed to permit only a small number of collection operations—e.g. two—before it must be replaced. In this case the conveyors of the collection device may need only a corresponding number of paddles. After collection of material the pull tab  406  can be torn off the framed  400  to pull tight a drawstring  416 , preventing release of the collected material. 
     It is to be understood that the collection device described above serves as an example only of how the invention can be put into practice. Some variants will now be described. 
     While the above described devices are intended particularly for collection of animal faeces, embodiments of the present invention may be put to any of a range of other uses. There are other situations which require collection of material without contamination of the collection device. Hazardous waste may require such treatment, for example. While the illustrated embodiments are manually actuated, others could use powered means to provide the required actions. 
     The liner  33 ,  402  may have a surface that is textured or spiky, or may have an adhesive surface to assist in collection. The paddles may have edges that are gapped, serrated (subject to their being suitably shaped not to damage the liner) or otherwise shaped to assist in collection of material. They may have flexible fingers to allow the contours of an uneven surface. They may incorporate magnets to draw pairs of paddles together, improving the seal across the liner  33 ,  402 . The paddles may be formed from a range of materials such as rubber, metal or plastics. It is preferred that the belts and the paddles should be formed from a single piece moulding. One pair of paddles may be followed, after a short space along the conveyor, by another, so that the two pairs of paddles form a double seal against escape of material. 
     The toothed belts  44 ,  46  could in other embodiments be replaced by for example chain, flat belts V belts etc. While the mechanism used to advance the liner and the collected material into the housing is referred to as “conveyor” at various points herein, this implies merely that it is able to convey the liner and collected material into the housing and does not necessarily require the use of chains or belts. For instance the liner could be advanced by rollers, or grabbed and pulled by a reciprocating device. 
     Many variations in the construction and operation of the collection device are possible, within the scope of the present invention. For example,  FIGS. 19 ,  20  and  21  show a generally cylindrical collection device  510  embodying the present invention. In this embodiment housing  512  is a hollow cylindrical body and carries a set of jaws  524  which are equiangularly spaced about the housing&#39;s central axis. The illustrated example has eight jaws  524  but a different number of jaws could be used. Each jaw  524  has its own conveyor  544  carrying paddles  564  which are triangular in shape and which tessellate when the jaws  524  are closed ( FIG. 21 ) to close the device&#39;s mouth and collect material into it. As in previous embodiments the collection device  510  has a liner to cover the jaws and protect them from contact with the collected material. The liner is omitted from  FIGS. 19 to 21 . The jaws  524  are coupled by gearing or some other actuating mechanism (not shown) to open and close in unison, and as in the earlier described embodiments once the jaws have been closed to collect waste material it is drawn into the housing  512  by the conveyors  544 . In the present embodiment the jaws  524  and the conveyors  544  are driven by electric motors via orbital gears housed in the top of the device&#39;s sliding casing  534 . The jaws  524  are supported by brackets  600  cantilevered from the sliding casing  534 . A switch  602  on an upper part of the housing  512  releases telescopic handle  518  to allow the housing  512  to be lowered to ground level and to open twin flaps  532  and advance the jaws  524 . The housing  512  is formed in two parts hinged to one another about line  606  in  FIG. 19 . Depressing a release button  604  allows the two parts of the housing to be opened about the hinge to allow collected material to be removed. 
     In other variants of the collection device a single movable jaw could be used. It could, for example, be opposed by a static jaw.