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CROSS REFERENCES TO RELATED APPLICATIONS 
       [0001]    The present application is a continuation-in-part of U.S. patent application Ser. No. 12/708,397, filed 02/18/2010 (Feb. 18, 2010), which claims the benefit of U.S. Provisional Patent Application Ser. No. 61/153,585 filed 02/18/2009 (Feb. 18, 2009); and further claims the benefit of U.S. Provisional Patent Application Ser. No. 61/316,963, filed 03/24/2010 (Mar. 24, 2010). 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       THE NAMES OR PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    Not applicable. 
       SEQUENCE LISTING 
       [0004]    Not applicable. 
       INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC 
       [0005]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0006]    1. Field of the Invention 
         [0007]    The present invention relates generally to hinge assemblies, and more particularly to hinges for closures, such as doors, windows, hatches, lids, ports, and the like, and also for panels or surface members that pivot in relation to another panel or surface member, such as shelves, awnings, ramps, gates, and the like. 
         [0008]    2. Discussion of Related Art including information disclosed under 37 CFR §§1.97, 1.98 
         [0009]    Locking hinges and hinge assemblies are known. Exemplary publications teaching such technology include: 
         [0010]    U.S. Pat. No. 5,820,288 to Cole, which teaches an adjustable tool with a locking hinge mechanism. The tool may be moved between a number of selectable positions through the use of a hinge pin, which is splined along its length and holds the portions of the tool together. The hinge pin is movable between an unlocked position and a locked position. In the unlocked position, the tool is adjustable, and in the locked position the tool is fixed in position and ready for use. 
         [0011]    U.S. Pat. No. 4,528,718 to Brockhaus shows a door hinge including a first and a second hinge member each having eyes with a hinge pin inserted through the eyes of the hinge members to connect them operatively together. The hinge pin is mounted so as to be freely rotatable relative to a first eye but secured against axial movement relative thereto. The hinge pin and a second eye are formed with axially extending splines engaged between them, and adjacent the splines also axially disposed is the hinge pin, which is formed with a cylindrical section that engages within a complementary cylindrical recess in the second eye, the cylindrical section having a diameter which is slightly greater than the addendum circle diameter of the splines. 
         [0012]    U.S. Pat. No. 3,448,486 to Wright, teaches a locking hinge with a sliding adjustable pintle for locking cabinets, doors, lids, and the like. The pintle is formed with splines and is adjustable to a locked and unlocked position. In the locked position the splines engage hinge knuckles such that the hinge is prevented from turning. In the open position, the splines are disengaged from the knuckles and the hinge is free to turn. 
         [0013]    The foregoing prior art reflects the current state of the art of which the present inventor is aware. Reference to, and discussion of, this prior art is intended to aid in discharging Applicant&#39;s acknowledged duty of candor in disclosing information that may be relevant to the examination of claims to the present invention. However, it is respectfully submitted that none of the above-indicated publications disclose, teach, suggest, show, or otherwise render obvious, either singly or when considered in combination, the invention described and claimed herein. 
       BRIEF SUMMARY OF THE INVENTION 
       [0014]    The present invention is a novel hinge assembly that includes a first hinge member having a leaf and a lower sleeve. The lower sleeve includes an upper cylindrical passage with a first diameter and a lower cylindrical passage axially disposed immediately under the upper cylindrical passage and having a second diameter smaller than that of the upper cylindrical passage. The lower cylindrical passage has an interior wall with either a geometrical shape or surface topography. A second hinge member includes a leaf portion and an upper sleeve, the upper sleeve including an upper female portion and a lower male element extending axially downwardly from the female portion and has an outer diameter sized to fit tightly into the opening of the upper cylindrical passage of the lower sleeve so as to provide a smooth pivotal connection between the first and second hinge members. The male element further includes a lower portion with an interior wall configured substantially identically to that of the interior wall of the lower cylindrical passage of the lower sleeve. A through hole passes through the upper sleeve elements. When the male element of the upper sleeve is inserted into the lower sleeve, the through hole is axially aligned with the upper cylindrical passage and the lower cylindrical passage of the lower sleeve. A hinge pin is inserted into the upper cylindrical passage of the second hinge member and the lower cylindrical passage of the first hinge member. The hinge pin includes an outer surface configured or contoured in such a way to cooperate with the configuration of the interior wall of the lower sleeve. The hinge pin has an elevated unlocked position and a depressed locked position, such that when in the unlocked position no portion of the hinge pin outer surface engages the interior walls to prevent pivotal rotation of the hinge members in relation to one another, and when pushed into the down and locked position, the outer surface of the hinge pin engages the interior walls to prevent the hinge members from rotating in relation to one another. 
         [0015]    The foregoing summary broadly sets out the more important features of the present invention so that the detailed description that follows may be better understood, and so that the present contributions to the art may be better appreciated. There are additional features of the invention that will be described in the detailed description of the preferred embodiments of the invention which will form the subject matter of the claims appended hereto. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0016]    The invention will be better understood and its objects and advantages will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein: 
           [0017]      FIG. 1  is an upper front perspective view showing the inventive hinge assembly in a fully open and unlocked position; 
           [0018]      FIG. 1A  is a top plan view thereof; 
           [0019]      FIG. 2  is an upper front perspective view showing the possible hinge leaves rotation about the hinge pin when in an unlocked position so as to assume a partly closed position; 
           [0020]      FIG. 2A  is a top plan view thereof; 
           [0021]      FIG. 3  shows the hinge assembly in a partly closed position and the hinge pin pushed into a locked position to prohibit all hinge leaf rotation; 
           [0022]      FIG. 4  is an exploded upper front perspective view of the hinge of  FIGS. 1-3 ; 
           [0023]      FIG. 5  is an exploded front view in elevation showing the upper and lower hinge sleeves in cross section; 
           [0024]      FIG. 6A  is a partial cross-sectional front view in elevation taken along section lines  6 A- 6 A of  FIG. 1  showing the hinge in a locked position; 
           [0025]      FIG. 6B  is a partial cross-sectional front view in elevation showing the hinge in an unlocked position; 
           [0026]      FIG. 7  is a detailed view taken along section line  7 - 7  of  FIG. 6B , showing the spring loaded ball bearing detent used to prevent unwanted migration of the hinge pintle from either the unlocked or locked position; 
           [0027]      FIG. 8  is an upper cross-sectional view showing the splined interior of the lower hinge leaf taken along section line  8 - 8  of  FIG. 5 ; 
           [0028]      FIG. 9A  shows an alternative configuration or shape for the exterior of the locking element of the hinge sleeve; 
           [0029]      FIG. 9B  shows yet another alternative configuration for the locking element of the hinge sleeve; 
           [0030]      FIG. 10  is a cross-sectional side view in elevation showing the upper and lower sleeve portions and hinge pin of a second preferred embodiment of the inventive locking hinge; 
           [0031]      FIG. 11  is a cross-sectional side view in elevation showing the upper and lower sleeve portions and hinge pint of a third preferred embodiment; 
           [0032]      FIG. 12  is a cross-sectional side view in elevation showing the upper and lower sleeve portions and hinge pint of a fourth preferred embodiment; 
           [0033]      FIG. 13A  is an upper front left perspective view of a fifth preferred embodiment of the present invention showing the hinge in the unlocked position; 
           [0034]      FIG. 13B  is an upper front perspective showing the hinge in the locked position; 
           [0035]      FIG. 14  is a top plan view thereof; 
           [0036]      FIG. 15  is a cross-sectional top plan view showing the fifth preferred embodiment installed on a door frame and illustrating the pivot range of the latch leaf from the unlocked to the locked position; 
           [0037]      FIG. 16  is an exploded upper front perspective view of the fifth preferred embodiment; 
           [0038]      FIG. 17  is an exploded front cross-sectional view in elevation taken along section lines  18 A- 18 A of  FIG. 14 ; 
           [0039]      FIG. 18A  is a front cross-sectional view showing the hinge in the locked position; 
           [0040]      FIG. 18B  is a front cross-sectional view showing the hinge in the unlocked position; 
           [0041]      FIG. 19A  is an upper front left perspective view of a sixth preferred embodiment of the present invention showing the hinge in the unlocked position; 
           [0042]      FIG. 19B  is an upper front perspective showing the hinge in the locked position; 
           [0043]      FIG. 20  is a top plan view thereof; 
           [0044]      FIG. 21A  is a cross-sectional top plan view showing the sixth preferred embodiment installed on a door frame and illustrating the pivot range of the latch leaf from the unlocked to the locked position; 
           [0045]      FIG. 21B  is the same cross-sectional top plan view showing the latch leaf is a partially opened position; 
           [0046]      FIG. 22  is an exploded upper front perspective view of the sixth preferred embodiment; 
           [0047]      FIG. 23  is an exploded front cross-sectional view in elevation taken along section lines  24 A- 24 A of  FIG. 20 ; 
           [0048]      FIG. 24A  is a front cross-sectional view showing the hinge in the unlocked position; 
           [0049]    and 
           [0050]      FIG. 24B  is a front cross-sectional view showing the hinge in the locked position. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0051]    Referring first to  FIGS. 1 through 12 , wherein like reference numerals refer to like components in the various views, there is illustrated therein a new and improved locking hinge assembly, generally denominated  100  herein. These views collectively show that the inventive hinge assembly includes a first hinge member  110  having a leaf portion  120  and a lower cylindrical sleeve portion (a gudgeon or eye)  130 , which is roughly half the height of the leaf portion in dimension and extends along and is integral with the lower half of the interior edge  140  of the leaf portion. The lower sleeve  130  has an upper cylindrical passage  150  with a first diameter  160  and a lower cylindrical passage  170  axially disposed immediately under the upper cylindrical passage  150  and having a second diameter  180  smaller than that of the upper cylindrical passage. The lower cylindrical passage has an interior wall  190  that is splined ( FIG. 8 ) or otherwise provided with a surface topography, e.g., gear teeth  192  ( FIG. 9A ) or with a cross-sectional shape  194  ( FIG. 9B ) so as to function as a locking element in cooperation with the hinge pin (described fully below). 
         [0052]    The hinge assembly next includes a second hinge member  200  having a leaf portion  210  and an upper sleeve (eye or gudgeon)  220 , the upper sleeve including an upper female portion  230  also comprising roughly half the height of the leaf portion and integral with the upper half of the inner edge  240  of the leaf portion. The upper sleeve further includes a lower male element  250  extending axially downwardly from the female portion and having an outer diameter  260  sized for a tight fit insertion into the opening of the upper cylindrical passage  150  of the lower sleeve  130  in a manner well known in the art so as to provide a smooth pivotal connection between the two hinge members. A lower portion  270  of the male element interior wall  280  is splined  290  or otherwise configured or shaped identically to that of the interior wall  190  of the lower cylindrical passage  170  of the lower sleeve  130 . 
         [0053]    The upper sleeve includes a recess  300  (or countersink) at its upper end  310  and having a first diameter  320  and a cylindrical through hole  330  having a second diameter  340 . When the male element of the upper sleeve is inserted into the lower sleeve  130 , the through hole  330  is axially aligned with the upper cylindrical passage  150  and the lower cylindrical passage  170  of the lower sleeve  130  so as to accommodate insertion of a hinge pin  350 . The hinge pin includes an upper end  360  capped by an upper nut  370  threadably installed on the hinge pin. A helical compression spring  380  is disposed between the underside of the upper nut and the base  390  of the recess  300  in the upper sleeve. A lower nut  400  is threadably installed on the lower end  410  of the hinge pin. The helical compression spring is optional and is needed only when a single leaf hinge is employed, such as in a gate installation. While the spring may be employed to assist in keeping the hinge pin in an elevated (unlocked) position, the detent mechanism described below is sufficient for most applications. 
         [0054]    Next, the outer surface  420  of a lower portion  430  of the hinge pin includes splines, gear teeth, or a shape or geometric cross-sectional configuration  440  that cooperates with the splined interior wall  190  of the lower sleeve  130  to prevent rotation of the hinge pin. It will be seen that when the hinge is pushed up into the unlocked position, no portion of the hinge pin splines engages the splines (or other topography or shape) to prevent pivotal rotation of the hinge. 
         [0055]    The hinge pin further includes at least one, and preferably two, detent mechanisms, comprising first and second ball and spring combinations  450 ,  460 , disposed in a through hole  470  drilled through the pin. A single spring may be employed with balls disposed at each end, and the balls are thus biased against the opposing sides of the interior portion of the female portion of the upper sleeve as the hinge pin travels through the upper sleeve. It will be seen that when the hinge pin is pushed down into the unlocked position ( FIG. 6A ) ball and spring combinations disposed in the through hole of the hinge pin cooperates with female portion of the upper sleeve prevent excursion of the hinge upwardly. When the hinge pin is pushed upwardly and out of the locked configuration ( FIG. 6B ), the helical compression spring  380  (if provided) and the ball and spring combinations  450 ,  460  work to prevent unwanted drop of the hinge pin back into the locked position. When in the locked position, the splines on the hinge pin engage both the interior wall  190  of the lower cylindrical passage  170  of the lower sleeve  130  and the splines of the male element interior wall  290  such that the hinge members are prevented from pivoting relative to one another. 
         [0056]    In the illustrated exemplary embodiment, the hinge members are shown as conventional butt/mortise door hinges, each having a plurality of holes  480 ,  490 , for securing the hinge member to a door and/or door frame, though countless other hinge styles and configurations may incorporate the inventive system disclosed herein. 
         [0057]    Referring next to  FIGS. 10-12 , there is shown a second, a third, and a fourth preferred embodiments, respectively,  500 ,  600 ,  700 , of the novel locking hinge assembly, each providing a slightly different structural relationship of the operative elements of the invention. It will be appreciated that the changes relate principally to the relocation of the cooperative splined elements and the detent mechanism either upwardly or downwardly from the positions shown in the first preferred embodiment. In all other material respects, the inventive apparatus is essentially functionally identical to the above-described first preferred embodiment. 
         [0058]    In each of the second, third, and fourth preferred embodiments, the apparatus includes an upper sleeve portion  510 ,  610 ,  710 , a lower sleeve portion  520 ,  620 ,  720 , having a male element  530 ,  630 ,  730 , and a hinge pin  540 ,  640 ,  740  with splines  550 ,  650 ,  750 , disposed around its exterior circumference that engage splines  560 ,  660 ,  760  disposed on the interior wall of some portion of the lower sleeve when the pin is in the locked position (shown in all three views). The spring detents  570 ,  670 ,  770  prevent the pin from moving from its locked position. When pushed into the unlocked position, splines  580 ,  680 ,  780 , at one end of the hinge pin engage splines  590 ,  690 ,  790  disposed in the upper sleeve portion. 
         [0059]      FIGS. 13A through 18B  show yet another embodiment of the inventive hinge assembly. In this fifth preferred embodiment  800 , there is included a first hinge member  810  having a generally planar hinge leaf portion  820  and a lower cylindrical sleeve portion  830 , roughly half the height of the leaf portion in dimension and extends along and is integral with the lower half of an interior edge  840  of the leaf portion. The lower sleeve  830  has an upper cylindrical passage  850  with a first diameter  860  and a lower cylindrical passage  870  axially disposed immediately under the upper cylindrical passage  850  and having a second diameter  880  greater than that of the upper cylindrical passage. The upper cylindrical passage has an interior wall  890  having a geometry or otherwise provided with a surface topography, e.g., splines, gear teeth, etc., or with a cross-sectional shape so as to function as a locking element in cooperation with the hinge pin. The lower sleeve includes an upper male element  900  extending axially upwardly from a lower female portion  910  and having an outer diameter  920  sized for a tight fit insertion into the opening of the lower cylindrical passage of the lower sleeve portion of the second hinge member (described below). The fit gives rise to a smooth pivotal connection between the two hinge members. 
         [0060]    The hinge assembly next includes a second hinge member  930  having a latch leaf portion  940  and an upper sleeve  950 , the upper sleeve including a cylindrical upper female portion  960 , a medial portion  970  and a lower female portion  980 . The upper and lower female portions each have an interior diameter corresponding to the outer diameter of the male element of the lower sleeve. The medial portion has an interior wall  990  corresponding in shape and size with the interior wall  890  of the lower sleeve. 
         [0061]    The latch leaf portion  940  of the second hinge member  930 , unlike that of the leaf portion of the first hinge member, is U-shaped, not planar, with bends turning in a clockwise direction as viewed from above. In the locked position ( FIGS. 13B ,  14 ) the back side  1000  of the medial plate  1010  of leaf portion  940  is generally parallel with the back side  825  of the hinge leaf portion  820  of the first hinge member. The connecting segment  1020  is integral with the upper sleeve  950  and is oriented substantially normal relative to the medial plate. The distal segment  1030  is integral with the medial plate and is preferably generally parallel with the connecting segment, thus also substantially normal relative to the medial plate. 
         [0062]    As will be appreciated from the foregoing, when the male element  900  of the lower sleeve  830  is inserted into the lower female portion  980  of the upper sleeve  950 , the holes in the upper and lower sleeves become axially aligned and form a continuous bore into which a hinge pin  1040  may be inserted. The hinge pin includes a threaded upper end  1050 , a cylindrical middle portion  1060 , and a contoured lower portion  1070 , the latter having an outside shape that conforms to the interior wall of the medial portion  970  of the upper sleeve and the interior wall  890  of the upper male element  900 . The contoured lower portion  1070  is sized for very tight clearances from the interior walls of the medial portion and male element portion. The hinge pin further includes a round head sized for tight clearances from the interior diameter  880  of the lower female portion  910  of sleeve  830 . This allows the hinge pin to slide freely within the lower female portion. 
         [0063]    A helical compression spring  1090  is disposed in the upper female portion  960  of the upper sleeve, and when the hinge pin is inserted through the aligned lower and upper sleeves, it is threadably capped with a hinge pin cap  1200 . 
         [0064]    As can be seen best by referring to FIGS.  17  and  18 A- 18 B, the hinge pin has a length such that the most elevated position for the pin brings the base of the head into contact with the shoulder defined by the changing diameters between the lower and upper female portions of the lower sleeve. As seen in  FIG. 18A , the helical compression spring urges the hinge pin upward into that most elevated position, and in so doing brings the lower portion  1070  of the hinge pin into full engagement with the interior wall  890  of the male element  900  of the lower sleeve, and the interior wall  990  of medial portion  970  of the upper sleeve. 
         [0065]    As shown in  FIG. 18B , when the hinge pin cap is pushed down, the hinge pin lower portion is pushed out from both the interior wall  890  of the male element  900  and the interior wall  990  of medial portion  970 . At this time, the hinge is unlocked and the first and second hinge members can pivot freely in relation to one another. When the desired orientation of the leaf portions is achieved, the pin is simply released and allowed to elevate, thereby pulling the hinge pin back into the locked position. 
         [0066]    As shown in  FIG. 15 , this embodiment of the present invention is recess mounted on the door frame F on the handle side of the door D. The screw holes  1210  in the hinge leaf portion allow screws to be passed and countersunk for a flush surface. The latch leaf portion is then free to pivot a full 180 degrees from a full unlocked position  1220  to a fully locked position  1230 , which brings the back side  1000  of the hinge leaf portion into engagement with the interior side D 2  of the door. In this position, the contoured sides of the lower portion of the hinge pin are brought into alignment with the configured interior wall of the medial portion of the upper sleeve and interior wall of the male element of the lower sleeve, as described above. The action required by the user to free the hinge latch for pivotal movement amounts to nothing more than depressing the hinge pin at its cap. To return the locking hinge to its unlocked position, the user again need only depress the hinge pin. As long as the pin is fully depressed, the latch will pivot freely. As soon as it is released, the latch will “catch” and lock wherever the configured portions are fully approximated. 
         [0067]    In this way, the locking hinge of the present invention gives a home owner either supplemental or replacement door lock protection. A door can be either temporarily or permanently locked using the inventive hinge. If an emergency were to arise necessitating the rapid unlocking of the door to allow ingress of persons from outside or egress of persons from inside the structure, the lock can be opened quite quickly with the simple press of a button (i.e., the hinge pin cap). Conversely, if the door were unlocked and an occupant felt the need to lock it urgently, it can be swung into the locked position in one swift move. 
         [0068]    In relation to known conventional door hinges, a significant distinguishing feature of the inventive locking hinge resides in the effect of removing the hinge pin. In the case of the prior art, the hinges essentially separate when the hinge pin is removed, much to the consternation of any handyman who has tried to remove or hang a door. By contrast, the inventive locking hinge includes a male element that slips into a female element so as to prevent such a separation. Indeed, the combined hinge members provide a fully functional hinge even without the hinge pin installed. The hinge pin provides further stability, but its essential function is not to hold the hinge members together, but to provide a rapid locking/unlocking mechanism. 
         [0069]    In an alternative expression  1300 , shown in  FIGS. 19A-24B , the locking hinge of the present invention can employ a pull, rather than push, mechanism as a lock release. 
         [0070]      FIGS. 19A through 24B  show yet another embodiment of the inventive hinge assembly. This sixth preferred embodiment  1300  includes a first hinge member  1310  having a generally planar hinge leaf portion  1320  and a lower cylindrical sleeve portion  1330  integral with and extending along a lower portion of an interior edge  1340  of the hinge leaf portion. The lower sleeve  1330  has an upper passage  1350  that is square or rectangular in cross section and a lower passage  1360  disposed immediately under the upper passage. The lower passage may be cylindrical or configured with an alternative cross-sectional shape. In any event, it is sized so as to provide free clearance of the interior wall  1370  of the lower passage as the hinge leaf portion rotates about the hinge pin, as described below. The upper cylindrical passage has an interior wall  1380  having a geometry or otherwise provided with a surface topography, e.g., splines, gear teeth, etc., or with a cross-sectional shape so as to function as a locking element in cooperation with the hinge pin. The lower sleeve  1330  includes an upper male element  1390  extending axially upwardly from a lower female portion  1400  and having an outer diameter  1410  sized for a tight fit pivotal insertion into the lower cylindrical passage  1420  of the lower sleeve portion  1430  of the second hinge member  1440 . 
         [0071]    As with all previous embodiments, the sixth preferred embodiment next includes a second hinge member  1440  having a latch leaf portion  1450  and an upper sleeve  1460 , the upper sleeve including an upper female portion  1470 , a choked down medial portion  1480  and a lower female portion  1420 . The upper female portion may be cylindrical or have an alternative cross sectional shape. However, the lower female portion is cylindrical and has an interior diameter slightly larger than the outer diameter of the male element of the lower sleeve. The medial portion  1480  has an interior wall  1490  corresponding in shape and size with the locking surface of the hinge pin (described below). 
         [0072]    The latch leaf portion  1450  of the second hinge member  1440  is L-shaped, with a stem  1500  integral with the upper sleeve  1460  and a single outboard bend or turn  1510  directed in a counterclockwise direction as viewed from above (see, e.g.,  FIG. 20 ) to form a door-engaging leg  1520 . 
         [0073]    The hinge pin employed in this embodiment departs from the design employed in the earlier embodiments. Rather than having a generally cylindrical cross-sectional shape, the pin has a generally square or rectangular cross-sectional shape, and only a portion of the hinge pin is cylindrical. Shapes other than square or rectangular may be employed for the purpose of defining the possible number of stop or lock positions available to the user when opening and closing the latch (which may be better appreciated by referring to  FIGS. 21A-21B ). Referring for the moment to  FIG. 23 , it is seen that the hinge pin  1530  comprises a head  1540  having a square or rectangular cross-sectional shape, an upper medial cylindrical neck  1550 , and a lower portion  1560  preferably, though not necessarily, having a cross-sectional shape or surface topography conforming to that of head  1540 . At its lower end, hinge pin  1530  includes a threaded hole  1565  that receives the thread end of a lock pin  1570  inserted through a hole  1580  in the base  1590  of a knob  1690 . A spring  1610  is axially disposed around the shaft of lock pin  1570 , interposed between the head  1620  of the lock pin and the inboard side  1630  of the knob. 
         [0074]    Lower sleeve  1400  includes a detent or recess  1640  in which knob  1600  is seated when in the locked position. Referring principally to  FIGS. 24A-24B , it will be seen that pulling on knob  1590  compresses spring  1610  and brings base  1590  of knob  1600  out of recess  1640  and allows lock pin  1570  to slide vertically up slot  1650  disposed in the side of lower sleeve  1400 . This elevates hinge pin  1530  so as to bring cylindrical medial neck  1550  into the interior space of medial portion  1480  of upper sleeve  1460 , thereby unlocking the hinge so as to permit free pivotal movement of the latch leaf portion about the male element  1390  of the first hinge member and on the axis of the hinge pin. 
         [0075]    A stopper  1660  comprising a circular cap  1670  with an elongate finger  1680  is screwed onto the upper edge  1690  of hinge leaf  1320  with screws  1700  so as to prevent the two hinge members from separating. This may be fabricated from a metal identical to that of the hinge elements or from a different, harder material according to the anticipated uses for the locking hinge. 
         [0076]    Unique to this embodiment, and as shown in  FIG. 21B , the latch leaf may be opened in stages, such that an intermediate “open” position can be achieved, thereby giving an occupant the option of having the door effectively locked (prevented from being opened to a degree needed for ingress and egress, but still allowing the occupant to look through the crack in the partially open door to determine the identity of a person standing outside. It also allows air to be circulated through the opening without having to open the door fully or to leave it unlocked. 
         [0077]    As will be readily appreciated, the present invention has nearly unlimited applications well beyond the simple installation on doors for occupied structures. Not only may it be employed for use on lids and closures of virtually any kind, but it can be used as the hinge element for planar members that pivot in position in relation to another planar member, ready examples being workbenches, shelves, partitioning walls, and the like. Other straightforward applications include boat hatches, gates, doors, tool and tackle box lids, and so forth. The possible 
         [0078]    The above disclosure is sufficient to enable one of ordinary skill in the art to practice the invention, and provides the best mode of practicing the invention presently contemplated by the inventor. While there is provided herein a full and complete disclosure of the preferred embodiments of this invention, it is not desired to limit the invention to the exact construction, dimensional relationships, and operation shown and described. Various modifications, alternative constructions, changes and equivalents will readily occur to those skilled in the art and may be employed, as suitable, without departing from the true spirit and scope of the invention. Such changes might involve alternative materials, components, structural arrangements, sizes, shapes, forms, functions, operational features or the like. 
         [0079]    Therefore, the above description and illustrations should not be construed as limiting the scope of the invention, which is defined by the appended claims.

Summary:
A locking hinge with a sliding hinge pin that selectively places the hinge in either a locked or unlocked configuration. The hinge pin includes cylindrical and contoured upper and lower exterior parts that cooperate with contoured upper and lower portions of the interior wall of the lower and upper sleeve members of the hinge. When in the locked configuration the lower contoured part of the hinge pin engages the contoured portion of the lower sleeve member and the upper contoured part engages the contoured portion of the interior wall of the upper sleeve, and in the unlocked configuration the lower contoured part of the hinge pin does not engage the contoured portion of the interior wall of the lower sleeve and the upper contoured part of the hinge pin does not engage the contoured portion of the interior wall of the upper sleeve.