BACKGROUND OF THE INVENTION 
     The invention generally relates to window safety bars and fire escapes, and more particularly to a unitary window safety bars and exterior fire escape ladder, and in which there is no loss of effectiveness of purpose and use in either category due to the other. 
     The prior art teaches combinations with similar purposes to put in building window casings, but in which the effectiveness of each part of the combination is reduced by the other both in purpose and use. Thus the effectiveness of purpose of the window safety bars is reduced when anyone outside a building can release the window safety bars in the window casings thereof, and the effectiveness of the exterior fire escape ladder is reduced when everyone inside the building cannot release the window safety bars. The effectiveness in use of said combinations as a fire escape ladder is reduced when access thereto is physically dangerous and difficult for the elderly, infirm, sedentary, and women, the last because of the type of clothing normally worn. 
     In the following references, Scholer, U.S. Pat. No. 1,629,541 teaches a safety metal grill that is locked in place and can only be used as a fire escape when the possessor of the key for the lock is present. Also the grill is pivoted to a window sill for swinging outwardly and downwardly therefrom as a fire escape ladder and thereby requiring a user to crawl out on the sill and half hanging thereover to reach backward with a foot to find a ladder rung. 
     Momo, U.S. Pat. No. 1,072,624 teaches a window railing lattice extendable downwardly from just above a window sill or swung outwardly therefrom for poor access. 
     Scherrer, U.S. Pat. No. 956,183 and 573,165 teach swinging casements with difficult access similar to Momo and requiring a 90° turn with one backward handhole. 
     Bessier, U.S. Pat. No. 269,377 and Chipley, U.S. Pat. No. 145,844 also teach swinging fire escape ladders, all except Chipley swinging normal to a window casing, and Chipley teaching shutters swinging 180° thereto, all posing risk of falling to gain access. 
     The invention teaches a unitary window safety bars and fire escape ladder for either use by anyone inside the window of a building in which it is installed. As an exterior fire escape ladder, easy access for a person within the building is provided from a standing position on a window sill facing forward and holding with both hands to horizontal side supports by taking a short step forward to a vertical ladder cantilevered outwardly from the building and descending between building and ladder to similar ladders in lower windows until the ground is reached, an escape well within the abilities of all ambulatory persons. 
     A second embodiment of the invention for a one story building only teaches the same spacing between safety bars and ladder rungs and backward access from standing position on a window sill with angled frame sides providing handrails and descent facing the building to the ground as in using a leaning conventional ladder. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a unitary window safety bars and exterior fire escape ladder in which the dual uses and purposes are not adversely affected by the unitary apparatus. 
     Another object of the invention is to provide a unitary window safety bars and exterior fire escape ladder which is usable by the elderly, infirm, sedentary, and women normally clothed. 
     Yet another object of the invention is to provide for one story buildings a unitary window safety bars and exterior fire escape ladder that is simpler and more economical to make and install than the embodiment for installation and use in multi-storied buildings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front view of the invention mounted as window safety bars in a building window casing; 
     FIG. 2 is a front view of the invention pivotally and slidably adjusted as an exterior fire escape ladder; 
     FIG. 3 is a side elevation of the invention as shown in FIG. 2; 
     FIG. 4 is a cross-sectional view taken along section line 4--4 of FIG. 1; 
     FIG. 5 is a three dimensional view of the invention as shown in FIG. 3; 
     FIG. 6 (a) and (b) are three dimensional enlarged views of the locking device of FIG. 1 shown (a) unlocked, and (b) locked; 
     FIG. 7 is a three dimensional view of a second embodiment of the invention mounted as window safety bars in a partially shown one story building; 
     FIG. 8 shows the matter of FIG. 7 adjusted as an exterior fire escape ladder; 
     FIG. 9 is a cross-sectional view taken along section line 9--9 of FIG. 7; and 
     FIG. 10 is a cross-sectional view taken along section lines 10--10 of FIG. 8. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIGS. 1-6, the invention comprises a pair of slidably interfitting outer and inner frames 20 and 22, each having a plurality of horizontal bars 24 and 25 respectively fixed therein spaced equally and vertically apart. A pair of side supports 26 pivotally mounts said frames, when slidably coincident, in a window casing 28 as window safety bars. A locking device 30 is operably mounted in the sides and sill of said window casing, and is operable only from inside said window casing to lock and unlock side supports 26 for pivoting said frames in and out of said window casing for extended use as an exterior fire escape ladder. 
     Referring particularly to FIGS. 2-5, outer frame 20 comprises elongated sides 21 made from angle stock, &#34;L&#34; shaped in cross-section (see FIG. 4), and extending along the sides of window casing 28 from sill 46 to lintel 47 and oppositely disposed for long side of the &#34;Ls&#34; to be transverse the plane of said window casing and the short side of the &#34;Ls&#34; to be parallel with said plane. Horizontal safety bars 24 are fixed in the long side of the &#34;L&#34; of the frame sides 21 extending therebetween, and a stop bar 52 is fixed between said short side of the &#34;Ls&#34; adjacent the sill 46 ends of said frame 20 for engaging an associated stop bar 50 of inner frame 22 as will be explained hereafter. 
     Inner frame 22 comprises elongated sides 23 made from channel stock, &#34;U&#34; shaped but with a flat base in cross-section (see FIG. 4), and extending from sill to lintel of said window casing similarly disposed to slidably engage outer frame sides 23 &#34;L&#34; shaped in cross-section with the flat base of the &#34;U&#39;s&#34; to said short side of the &#34;L&#39;s&#34; and opposing sides of the &#34;U&#39;s&#34; to opposite long sides of the &#34;L&#39;s&#34;. Horizontal safety bars 25, shorter than safety bars 24, are fixed in the unengaged sides of the &#34;U&#34; of the frame 22 sides 23 and extending therebetween. A stop bar 50 is fixed to the flat bases of the &#34;U&#39;s&#34; adjacent the lintel end of sides 22 and adapted to engage said stop bar 52 of the outer frame 20 to prevent separation of said inner and outer frames when slidably extending downwardly. Said inner frame is slidably insertable in said outer frame from the lintel end as shown in FIG. 4 and is retainable therein by said outer frame and stop bars 50 and 52. 
     Referring to FIGS. 3-5, side supports 26 comprise a pair of flat bars having oppositely disposed ends 43 and 44 with transverse pivot holes 38 defined in each said end and locking slots 54 defined therebetween. Stops 42 are fixed below respective ends 44 and outboard of pivot holes 38. The side supports are pivoted to outer frame 20 by pivots 36 through pivot holes 38 in ends 44 and adjacent the frame&#39;s lintel end. Oppositely disposed support ends 43 are respectively pivoted to window casing sides 21 below the casing lintel a distance equal to that from support end 44 to lower pivot hole 38. A cable stop 40 is fixed to each support 26 intermediate its ends 43 and 44 and to each window casing side between the supports&#39; fixed ends and lintel 47. In use stops 42 restrict the pivoting on outer frame 20 on said supports to 90°, and cable stops 40 restrict the pivoting of said supports to 90° to the window casing. 
     Referring to FIGS. 1, 5 and 6, locking device 30 comprises locking slots 54 defined in said window casing sides between the pivoted ends 43 of side supports 26 and cable stops 40 ends fixed to sides of window casing 28, and in alignment with locking slots 54 defined in said side supports when said supports are pivoted into said window casing. Cylinder segments 56 are respectively mounted for rotation on parallel axes 57 with flat portions of said segments respectively flush with respective locking slots 54 defined therein and rotatable to extend partially therethrough. Cylindrical members 58 are respectively mounted for rotation on parallel axes 60 in said casing sill 46 vertically below and in the same plane as cylinder segments 56 and axes 56 and 57. A pair of rods 62 respectively connect oppositely disposed horizontal radial extremities of respective vertically aligned cylinder segments with the same radial extremities of associated cylindrical members, and a similar rod 62 connects upper radial extremities of said cylindrical members. Another rod 66 connects a lower radial extremity of a cylindrical member 58 and a manual crank mechanism 61 mounted in a building wall adjacent said window casing and adapted to rotate the cylindrical member a quarter turn counterclockwise thereby rotating the other cylindrical member and both the connected cylinder segments on their respective parallel axes and in the same plane in alignment for said segments to project through said slots 54 in said casing and side support to lock the side support and frames 20 and 22 in the window casing. A quarter turn of said cylindrical member clockwise unlocks said frames from the casing (see FIG. 6 (a) and (b)). The manual crank mechanism is mounted out of reach of anyone outside the window casing and comprises a dial crank 63 fixed on the outboard end of a shaft 64 parallel to axes 57 and 60 of the rotatable members and segments 56 and 58. A lever 65 is fixed by an end normal to said shaft and in the plane of members 58. The free end of said lever 65 is connected to said rod 66 free end, whereby turning or rotating said dial crank 63 clockwise rotates said members counterclockwise, and rotating said dial crank counterclockwise rotates said members clockwise. 
     A second embodiment of the invention (see FIGS. 7-10) also comprises a pair of slidably interfitting frames as in the first embodiment except that an outer frame 66 is channel shaped but larger than inner frame 68 which is similar to the inner frame of FIG. 4. The change was made necessary by the absence of safety bars 24 in the outer frame for holding the inner frame 68 in operable association therewith. Side supports 26 of the first embodiment are omitted and the outer frame 66 is pivoted to window casing sides adjacent said casing lintel. In the locking device 30 of the first embodiment, the cylindrical members 58 and window casing slots 54 are omitted to provide a locking device 70 having a manual crank mechanism 61 identical with that of the first embodiment that rotate cylinder segments 56 directly to project through locking slots 71 defined in the sill of window and outer frame in alignment, said segments being mounted in the window sill. 
     With the first embodiment locked as window safety bars in a window casing, to adjust as an exterior fire escape ladder, anyone inside the building rotates the dial crank 63 to unlock the locking device 30 and release side supports 26 from the window casing sides. A push against the upper part of the frames 20 and 22 pivots side supports 26 outward and downward 90°, as limited by cable stop 40. Frames 20 and 22 are carried free of window sill 46 allowing the inner frame 22 to extend slidably downward by gravity until stops 50 and 52 engage to prevent separation of the frames. A person exiting the building steps on the window sill, grasps the side supports with respective hands and steps forward on to a horizontal bar now a ladder rung 24, shifting his hands to grasp the frame sides 21. The frames are prevented from swinging out around outboard pivots 38 more than normal to the side supports. The person descends supported vertically between the building and the ladder to a similar lower ladder and/or the ground, as shown in FIGS. 2 and 3. To adjust back to window bars, a person inside the building reaches out of the window grasping the frame sides 21 and lifting them upward, pivoting the side supports upwardly and inwardly until frame 22 contacts the window sill. The grasps are shifted to frame sides 23 of bars 25 and the inner frame slidably raised into coincidence with outer frame 20 and both pulled inwardly by bars 24 and 25 into the window casing 28. The person then steps to the dial crank and rotates it to lock the side supports which have also pivoted upward and inward into the window frame with the frames into the window casing. 
     With the second embodiment locked as window safety bars in a window casing, to adjust as an exterior fire escape ladder to the ground, anyone inside the building rotates the dial crank 63 of the locking device 30 to unlock locking device 70 and release the frames from the window sill. A push against the bottom of the frames 66 and 68 pivots them outwardly around pivots 69 adjacent the top of the frames and lintel of the window casing, clear of the window sill. Inner frame 68 slides downward until prevented from sliding out of frame 66 by stops 50 and 52 or by the ground. A person leaving the building stands facing inward on the window sill and grasping the angled sides of frame 66 steps on the horizontal bars 25 of the inner frame and descends as on a leaning straight ladder. To adjust back to window bars, the inner frame can be raised either from inside or outside the building and both frames seated in the window casing. However, the frames can only be locked in the casing by a person inside stepping to the dial crank 63, out of reach from the window, and turning it to lock the frames to the window sill.
A pair of frames are slidably interfitted on a common slide axis. Safety bars placed normal to the slide axis and alternately opposite sides of the slide axis, are fixed in the frames in sliding noninterference and for halving space between bars when frames are slidably coincident. Frames are pivotally fixed in the lintel or upper half of a building window casing for pivoting outwardly. A locking device, mounted in a window casing and controllable by anyone in the building and remote from the casing, locks the frames slidably and pivotally coincident in the casing as closely spaced window safety bars, and similarly unlocks the frames to pivot them outwardly clear of the window sill for slidable extension downwardly as an exterior fire escape ladder with double spaced rungs and angled handrails for standing entry on the ladder from the window sill. Bar stops fixed to opposite ends of the respective frames prevent separation of the slidably interfitting frames.