Abstract:
A lockset for a door has knobs which are generally conical in shape and tapered inwardly with distance from the door surface to prevent attachment of a noose. Finger receiving concavities are provided circumferentially about the inward tapering surface of the knob to facilitate grasping without providing any projection about which a noose can be secured. One or both knobs of the lockset can optionally be provided with a handle at its pistol end from the door which can be grasped between fingers to further enhance gripping ability while avoiding the provision of a projection to which a noose can be attached.

Description:
BACKGROUND OF THE INVENTION  
       [0001]    The present invention is directed to an improved lockset of the type commonly used for latching and opening a door. More specifically, the invention is provides a lockset having knobs which can be securely grasped and turned by one who is infirm in order to release a door latch but on which a noose cannot be securely tied. 
         [0002]    Psychiatric patients have been known to attempt suicide by hanging while in hospitals or other psychiatric institutions. Hanging is sometimes accomplished by passing a noose formed from a bed sheet, dressing gown, shoe lace, dental floss, or other readily available elongated flexible object available to the patient, to a fixture from which the patient may be hanged. 
         [0003]    Although rooms at psychiatric institutions are, to the extent possible, kept free of fixtures to which a noose can be attached, virtually every room has a door and door handle for opening and closing the door. Moreover, furniture in such rooms sometimes is equipped with handles. Such door knobs or handles are commonly of a configuration which permits a noose to be secured to them with sufficient stability to support the weight of a patient and, thereby, enable asphyxiation of the patient by hanging. 
         [0004]    Psychiatric patients who may be inclined to commit hanging are often elderly and/or arthritic, and have difficulty grasping a door or drawer knob. The goals of providing a door knob or drawer knob configured to prevent attachment of a noose and that of making the door knob or drawer knob easily graspable by the patient who may have limited physical capacity to turn a knob are at odds with each other. 
       SUMMARY OF THE INVENTION  
       [0005]    The present invention provides a lockset with one or more door knobs configured to prevent attachment of a noose while enabling secure gripping for ease of unlatching a door. 
         [0006]    It is therefore an object to provide a lockset with one or more knobs to which a noose cannot be securely tied. 
         [0007]    Another object of the invention is to provide such a lockset with knobs which can be easily gripped and rotated to unlatch a door by a person having limited physical capacity. 
         [0008]    A further purpose of the invention is to provide a lockset which can be fitted into a standard door lockset opening while employing exposed knobs to which a noose cannot be securely affixed. 
         [0009]    Still a further objective of the invention is to provide a lockset having knobs which are easily gripped but present no surfaces or edges which can cause injury to a person gripping them. 
         [0010]    Other and further objects of the invention will be apparent from the following drawings and description of a preferred embodiment of the invention in which like reference numerals are used to identify like parts in the various view. 
     
    
     
       DESCRIPTION OF THE DRAWINGS  
         [0011]      FIG. 1  is a perspective view of a door unlatching assembly in accordance with the preferred embodiment of the invention shown in its intended environment; 
           [0012]      FIG. 2  is an exploded perspective view of the door unlatching assembly shown in  FIG. 1 ; 
           [0013]      FIG. 3  is a perspective view of a component of the door unlatching assembly shown in  FIGS. 1 and 2 ; 
           [0014]      FIG. 4  is a perspective view of a modified version of the component shown in  FIG. 3 ; 
           [0015]      FIG. 5  is a side sectional elevation view of the component shown in  FIG. 3 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0016]    Referring now to  FIG. 1  of the drawings, therein shown a lockset  1  for a door  3 . The lockset  1  has a conventional latch  5  which is operatively connected to a latch retractor  7  mounted within the door  3 . Connected to the latch retractor  7 , on each side of the door  3 , is a knob  9 ,  11  mounted on a respective rose  13 ,  14 , that can be rotated for retracting the latch  5  and thereby permitting the door to be opened. 
         [0017]    Referring now to  FIG. 2  of the drawings, the lockset latch retractor  7  of  FIG. 1  is conventional being mountable within a cylindrical opening drilled through the door  3 . The latch retractor  7  is provided with lips  15  which grasp a tab  17  on the spring-mounted reciprocating latch  5  as is conventional and will be known to those skilled in the art. 
         [0018]    Referring to  FIG. 5 , each knob,  9 ,  11  has a stepped central axial blind cylindrical bore with an enlarged portion  10  proximate the base of the knob  9 ,  11 , a narrower axial displaced portion  14  distal from the base of the knob  9 ,  11 , and an intermediate portion  12  disposed between the enlarged portion  10  and the narrower portion  14  of the knob center stepped cylindrical bore. 
         [0019]    A knob bushing  19  has a body with circular disc  23  and a central aperture. Extending from each from each side of the disc  23  is a hollow cylindrical boss  20  centered on the disc of the bushing  19 . A knob bushing  19  is mounted on each of the knobs  9 ,  11  by three mounting screws  21 . 
         [0020]    An end of the cylindrical boss  20  is received in the intermediate portion  12  of the bore while the disc  23  is received in the enlarged portion  10  of the bore. An actuator which is rotatable for causing the latch retractor  7  to unlatch the door is provided in the form of a spindle  25  extending from each knob  9 ,  11 . Each spindle  25  has a driving length with a square cross section and an axially displaced connecting length with a threaded cylindrical portion that is screwed into the end of the cylindrical boss  20  protruding from each of the knob bushings  19  opposite the end received in the intermediate bore portion  12  of the knob  9 ,  11 . When screwed fully into the boss  20  of each knob bushing  19 , the spindle extends into the narrower portion  14  of the central bore in each knob  9 ,  11 . 
         [0021]    Mounted on respective outer surfaces of the door  3  are the outside rose  13  and an inside rose  14 . Two posts  33  with threaded cylindrical bores secure the latch retractor  7  which is sandwiched between the outside rose  13  and inside rose  14 . Screws  35 , passed through apertures in the inside rose  14  and through the door  3  are received in the hollow threaded cylindrical posts  33  which are affixed to the outside rose  13 . 
         [0022]    Rotatably mounted within a central cylindrical bore in each of the outside rose  13  and inside rose  14  is a needle roller bearing  39  through which a respective spindle  25  of one of the knobs  9 ,  11  is passed. Each needle roller bearing is held in place by a washer  41  and retaining ring  43 . 
         [0023]    Referring additionally to  FIGS. 3 and 5  of the drawings, each knob  9 ,  11  is generally conical in shape and rotatably mounted with its maximum circumference adjacent its respective rose  13 ,  14 . That is, the maximum diameter of each cross section of each knob transverse to the axis decreases with increasing distance from its base which is mounted on its respective rose  13 ,  14 , adjacent the door  3 . 
         [0024]    Concavities  43  are equally spaced about a circumference of the tapered conical surface of each knob  9 ,  11 . The concavities  43  preferably have rounded edges. In the preferred embodiment of the invention there are six such concavities. However, the number of concavities can be increased or decreased within the scope of the invention. The circumference of each knob  9 ,  11  is free of any projections or grooves on or in which a noose could snag when pulled in a direction parallel to or away from the door  3 . 
         [0025]    The concavities  43  are generally shaped with parallel sides and rounded ends and are sized to accommodate the finger pads of a person in order to enable the knobs to be turned without slipping through the fingers. There are no projections or other raised surfaces on the circumference of each knob  9 ,  11  to which a noose can be secured. 
         [0026]    In accordance with the preferred embodiment of the invention, each of the knobs  9 ,  11  has at its end distal from its respective rose  13 ,  14 , an integral handle  16  having a rectangular face  18  with ends  20  that meet the tapered surface of the conical knob  9 ,  11 , and trapezoidal recesses  22  on opposite sides of the rectangular handle  16 . 
         [0027]    The handle  16  may be grasped between the fingers as an alternate way of gripping the knob  9 ,  11  for rotation in order to unlatch the lockset. A lip  24  surrounds each recesses  22  on three sides. The ends of each lip  24  meet a shoulder  26  having a planar surface orthogonal to the axis of rotation of the knobs  9 ,  11 . Each shoulder  26  serves as a stop for a finger when the handle  16  is grasped for rotating each knob  9 ,  11 . The recesses  22 , lips  24 , and shoulder  26  allow for a secure grasp of each knob  9 ,  11 , without slippage, for persons who are infirm or otherwise unable to tightly grip the knob  9 ,  11 . 
         [0028]    Referring now to  FIG. 4  of the drawings, there is shown a knob  9 ′ similar in shape to the knobs  9 ,  11  with the following exception. The end  45  of the knob  9 ′, intended to be distally mounted with respect to the door  3 , is truncated and does not have the rectangular handle  16  that is integral with the knobs  9 ,  11 . 
         [0029]    Elimination of the rectangular handle enables the knob  9 ′ to be axially shorter than the knobs  9 ,  11  with all other dimensions being equal. This can be advantageous for persons with small hands who do not require the use of a handle. The hands can be placed over the front of the knob  9 ′ with the fingers inserted into the concavities  43  for grasping and rotating the knob  9 ′. 
         [0030]    The knob  9 ′ is less costly to fabricate than the knobs  9 ,  11 , easier to clean due to fewer recessed surfaces, and may be considered more aesthetically pleasing to the eye. 
         [0031]    The knob  9 ′ may be substituted for either or both of the knobs  9 ,  11 , in accordance with the invention. 
         [0032]    It is to be appreciated that the foregoing is a description of a preferred embodiment of the invention to which modifications and variations may be made without departing from the spirit and scope of the invention.