Abstract:
A lock system includes keys, key blanks, keyways, and lock cylinders, and the keys or key blanks have opposite sides formed with grooves for cooperating with a conforming keyway. More particularly, the sides of the key or key blank have a portion grooved for registration, another portion grooved for top-level hierarchical master keying, and two other portions, one on each side of the blade, for further master key variations and different combinations. One of the two further sections being curvilinear and the other rectangular or angular cuts. The conforming keyway of the lock includes ridges and grooves corresponding to the grooves and ridges, respectively, of the key or key blank. Instruments other than keys or key blanks may be used to enter the grooves and ridges of the keyway to operate the lock without the use of a precisely configured key.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This application is a continuation-in-part of U.S. Pat. application Ser. No. 11/694,097, filed Mar. 30, 2007, now U.S. Pat. No. 7,412,860, the disclosure of which is hereby incorporated by reference. 

   FIELD OF THE INVENTION 
   This invention relates to improvements in keys, key blanks, keyways, and lock cylinders, particularly with regard to defining the profiles of keys, key blanks, and keyways using the shapes of ridges or grooves in a generally flat rectangular key blade profile. The shape of the key blank and key, of course, determines the shape of the keyway in a lock cylinder plug. 
   BACKGROUND AND PRIOR ART 
   The lock cylinders art is requiring higher and higher security and there is a need in the art for the development of a shape or profile of a cross section of key and corresponding shape of the keyway in the cylinder plug to accommodate a hierarchical lock providing high security. The shape of the keyway is the first barrier that rejects or filters an unauthorized key in attempt to operate the lock cylinder. 
   There is only a finite space in a lock cylinder plug that can be occupied by the key and that space must be structured to allow for the maximum number of unique keyway shapes to be able to develop lock systems of adequate size. In large modern lock systems it is usual to arrange the structure of the keyways in a manner so that at least three levels of a hierarchical system can be provided, with one master key blank at the top level of the system, some sub-master key blanks at a medium level and several change key blanks at the lowest level of the hierarchical system. A new key section design must be different from prior key sections so that the key blanks can be controlled by the manufacturer and the end user can benefit from the security offered by the exclusivity of this key control via the key blanks. 
   Unique key profile shapes provide for additional protection against unauthorized key copying. Most key blanks of the generally flat rectangular key profiles are manufactured with single pass formed milling cutters that shape the side of the key blank. The axis of rotation of the cutter is held parallel to the side of the blade. Keys using an undercut groove profile require additional form cutting on specially designed machines that are usually not available at commercial duplicator operations and thus the blanks are more difficult to copy or counterfeit. 
   Early in the development of lock cylinders, it became apparent that there were specific parameters that affected the size of the lock cylinder systems that could be developed and that there were many design factors that influenced the wear of the key and the cylinder and thus the longevity of the system. Key blanks were designed with these parameters in mind. Representative examples of the prior art include the following: 
   In U.S. Pat. No. 0,263,244, Taylor discloses a key blank design that offers an economically simple solution to the problem of having a key that moves too freely in the keyhole. This offers a very minimal keyway shape in the plug and key profile in the blank. 
   In U.S. Pat. No. 0,420,174, Taylor teaches a unique but limited master keying technique that uses a Y shaped key section in a plug that allows two differently shaped key profiles to contact their own areas of the non rotating tumbler pins. 
   In U.S. Pat. No. 0,567,305, Donavan discloses a method of expanding the number of key sections, thus increasing the available size of lock systems, by dividing the key blank height into various areas and using consistent warding techniques at these locations to develop hierarchical keyways or key profiles. This increases the system size of pin tumbler cylinders. The bittings of one key can be repeated on a different key blank, configured with a different key profile, and the cylinders into which these individual keys fit can also be operated by a higher level key designed to insert into both of the keyways. 
   In U.S. Pat. No. 0,608,069, Noack discloses an arrangement of key section warding that provides improved wear on the key and the key contact area on the tip of the locking pins. In addition it provides a narrow cross sectional width under the bitting area, thus making it difficult to manipulate pick tools under the tumbler pins. 
   In U.S. Pat. No. 3,499,304, M. Noujoks teaches a method of designing key section warding where both faces of the keys are provided with alternating ridges and grooves. It utilizes a master key blank that has all the grooves of the series but not the ridges, while the key blanks of a lower hierarchical level have varying ridges. 
   In U.S. Pat. Nos. 4,168,617 and 4,368,629, Prunbauer discloses more methods of designing key section warding where the master key will fit into the subordinate keyways but the lower keys will not fit into the master keyways. In one embodiment, the ridges and grooves defining the key section are of a rectangular cross-section shape, and the outwardly projecting variable ridge on the subordinate key extends laterally beyond any of the other variable ridges. The subordinate key is thicker at its further ridge than the master key is at any location. In another embodiment the master key is formed of a zigzag shape, that is with its opposite sides formed of a plurality of planar facets each of which is substantially parallel to a respective planar facet on the other side. 
   In U.S. Pat. No. 4,416,128, Steinbrink teaches another unique method of designing key sections where the longitudinal grooves on both sides of the key blank are formed with bottom faces that lay substantially along the arc of a circle. 
   In U.S. Pat. No. 4,653,298, Tietz discloses a method of designing master key section warding that incorporates an invariable or family profile near the bitting area on the blank, and the variations defining the individual key sections are located near the spline or bottom edge of the blank. Additionally there are at least two profile formations that cross a center line in the key blank, one ridge is extending beyond the surface of the blank, and the variations are made with longitudinal grooves having rectangular cross sections. 
   In U.S. Pat. No. 4,683,740, Errani illustrates a key section design that has a undercut groove shape making it very difficult to manipulate a pick tool in the keyway of the plug. The undercut groove is formed by means of cutters having their rotational axis inclined in relation to the sides of the key blank. 
   In U.S. Pat. Nos. 5,715,717 and 5,809,816, Widen teaches some very specific methods of designing key sections using a three sided undercut groove located closest to the bottom edge of the key blank and extending inwardly inclined towards the bottom of the key blank, or using an undercut groove with a substantially flat surface which is inclined towards the groove bottom surface. 
   In U.S. Pat. No. 6,145,357, Stefanescu teaches a method of designing master key section warding that utilizes a key blank with a T-shaped cross sectional area with all the profile ribs having specific curvilinear cross sectional contours, with rounded front and flank portions. 
   In U.S. Pat. No. 6,851,292, Kruhn discloses a method of designing lock and key warding that incorporates specific perpendicular groove surfaces on one side of the key section, and slanting surfaces on the other side that are positioned in a relationship designed to trap, or limit the motion of a picking tool inserted into the key way. 
   While the prior art has developed usable key sections, they fail to maximize the area of the plug and do not allow for the development of many large master keying systems. 
   SUMMARY OF THE INVENTION 
   This invention provides specific parameters for key section profiles and the corresponding keyways in a cylinder plug that allows for the development of many exclusive and non-interchangeable hierarchical master key systems. In order to accomplish this, the keyway and conforming key blade are considered separately for three vertical sections from the bottom edge of the keyway and blade up to the top edge of the blade. Each of the three sections is contoured or formed with specific variations of ridges and grooves that establish the lock&#39;s and key blank&#39;s positions within a hierarchical system or systems. The first, bottommost section of the blade has a registry groove for the positioning of any secondary side milling operations used in the manufacture of the blank, and the keyway has a conforming ridge in its bottommost section. This registry groove in the blade also allows for exact positioning of the blank in a key cutting or bitting machine. A second vertical section of the blade has at least one undercut longitudinal groove on at least one side of the blade, and the keyway has a conforming ridge or ridges in its second vertical section. The location and shape of the undercut groove in the second section of the blade determines the primary family of the hierarchical system. The third section of the blade, just below the bitting surface, may be divided into two sides. One of these sides has a variation of the key section profile determined by using longitudinal grooves of curved shaped forms that are shifted up and down the side of the blade to create the necessary variations. The position and curved form of the profiles on this side determines the secondary and subgroups in the family of the hierarchical system. On the other side of the third, or topmost section, of the blade, the variations in the key section profiles are determined by using longitudinal grooves having substantially rectangular or straight angular cross sections that vary in depth into the side of the blade. The position and depth of the angular profiles on this third section determine the individual location in the subgroup in the hierarchical system. The third section of the keyway has conforming curved ridges and grooves on one side thereof and conforming straight angular or rectangular ridges on the opposite side thereof. 
   By using these different but specific warding techniques at defined sections and on different sides of the blade it is possible to develop a structured system to allow the maximum number of new and unique key profile shapes. Additionally, by reversing the warding structure from side to side of the blade within different sections, it is possible to significantly increase the already large number of non-interchangeable key systems available, each providing adequate system size for the demands of modern security cylinder users. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view of a key blank of this invention. 
       FIG. 2  is a cross-sectional view taken along line a-a of  FIG. 1  and enlarged. 
       FIGS. 3 through 9  are cross-sectional views of other key configurations on the sides of the key blanks of this invention that illustrate the features of this invention. 
       FIG. 10  is an illustrative diagram of a simple three level hierarchical structure of keyways. 
       FIG. 11   a  is a side view of a key inserted into a lock cylinder. 
       FIG. 11   b  is a cross-section along the line A-A of  FIG. 11   a.    
       FIG. 11   c  is an end view of the lock cylinder of  FIG. 11   b , without the key inserted into the keyway. 
       FIG. 12   a  is a cross-section of a key and keyway along the line A-A in  FIG. 11   a , showing a different key and keyway than what is shown in  FIG. 11   b.    
       FIG. 12   b  is an end view of the lock cylinder of  FIG. 12   a , without the key inserted into the keyway. 
       FIG. 13   a  is a cross-section of a key and keyway along the line A-A in  FIG. 11   a , showing a different key and keyway than what is shown in  FIGS. 11   b  and  12   a.    
       FIG. 13   b  is an end view of the lock cylinder of  FIG. 13   a , without the key inserted into the keyway. 
       FIG. 14   a  is a cross-section of a key and keyway along the line A-A in  FIG. 11   a , wherein the keyway is the same keyway shown in  FIGS. 11   b  and  11   c , and the key is a master key. 
       FIG. 14   b  is an end view of the keyway of  FIG. 14   a  with an instrument inserted into the keyway for bypassing the profiles of the keyway. 
       FIG. 15   a  is a cross-section of a key and keyway along the line A-A in  FIG. 11   a , wherein the keyway is the same keyway shown in  FIGS. 12   a  and  12   b , and the key is the master key shown in  FIG. 14   a.    
       FIG. 15   b  is an end view of the keyway of  FIG. 15   a  with an instrument inserted into the keyway for bypassing the profiles of the keyway. 
       FIG. 16   a  is a cross-section of a key and keyway along the line A-A in  FIG. 11   a , wherein the keyway is the same keyway shown in  FIGS. 13   a  and  13   b , and the key is the master key shown in  FIGS. 14   a  and  15   a.    
       FIG. 16   b  is an end view of the keyway of  FIG. 16   a  with an instrument inserted into the keyway for bypassing the profiles of the keyway. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     FIG. 1  shows a perspective view of a key blank according to this invention. The key blank has a head or bow  1  for holding and turning the key and a blade  2  for inserting into a keyway of a lock cylinder. The keyway of the lock cylinder has a profile matching the profile of the key blade. The key blade has a top surface  3  into which key bittings (not shown) are cut to position elements such as pin tumblers in a lock cylinder as is well known in the art, see for example the patent to Medeco Security Locks U.S. Pat. No. 5,419,168. The blank has a bottom surface  4  and an end tip  5 . The end tip  5  may have a stop or other configuration; see for example U.S. Pat. No. 1,679,558. 
   The cross section of the key blank in one configuration is shown in  FIG. 2 .  FIG. 2  shows the top of the key blank blade  3  and the bottom of the key blank blade  4  and as shown in phantom lines three different sections. Section A, B, C and C′. As shown, Section A is adjacent to the bottom of the blade, Section C and C′ are adjacent to the top of the blade and Section B is in between Section A and Section C and C′. 
   Section A contains a groove  6  extending the length of the blade for registry purposes. When a key blank is being cut with bittings or machined for other grooves, registry groove  6  is used to provide a location for further operations relative to such groove. 
   In Section B there is an undercut groove  7  also extending the length of the blade. The undercut groove may be used to provide a first level in the hierarchical scheme for hierarchical master keying. 
   The area above the undercut groove is divided into the two sides C and C′ and the shapes and configurations of the grooves and ridges extending along these two sides are established by distinctly different parameters. The shapes in Section C are determined by a base curvilinear shape  110  on which is overlaid a number of partial circular curves  121 ,  122 ,  123 ,  124 ,  125  and  126 . These curves are all centered along the baseline  110 . The curves can project either outwardly as convex ridges or inwardly as concave grooves from the baseline creating either curved longitudinal ridges or curved longitudinal grooves along the side of the blank of Section C and below the top surface  3 . Similar families of curved shapes can be determined by variations in the base curvilinear shape  110 , i.e., a different curvilinear shape  110  can function as a center line for the various circular curves. Subgroups of these secondary families may be predetermined by the presence of either curved ridges, e.g.,  122 ,  124 ,  125 , or curved grooves, e.g.,  121 ,  123 ,  126 , and also by moving the base curvilinear shape  110  either up or down the side of the blank in relation to the registry groove  6  in Section A. 
   The shapes of the side of the key blade in Section C′ are determined by providing rectangular sections such as  134 ′ and straight angular shapes such as  131 ,  132 ′ and  133  and by varying the depths of these shapes into the side of the blank. There are a large number of other locations to provide grooves in Section C′ on this side of the blank, for example areas  135 ″,  136 ″ and  137 ″. The size of the grooves and the depths of the grooves that are formed in Section C′ on this side of the blank determine the individual position of the key cut from the key blank in the family hierarchical structure. 
     FIG. 3  shows the same cross-sectional view of the key blank but illustrates the base curve  110  shifted vertically in relation to registry groove  6  to produce a profile  10  in Section C on one side of the blade. The rectangular and straight angular shapes in Section C′ on the other side of the blade has variations, as compared to the key blank of  FIG. 2 , which define profile  50 . 
     FIG. 4  illustrates another key blank variation in which the base curve  110  is positioned at a different height in relation to the registry groove  6  for cutting the area on the side in Section C producing a profile indicated at  11 . The other side of the key blank in  FIG. 4  in Section C′ has a profile  50  showing the differences in cutting grooves and producing ridges. 
     FIG. 5  is a further cross-sectional view of the key blank illustrating the base curve  110  producing profile  12  on Section C of the key blank and profile  50  on the other side in Section C′ of the key blank. Profile  12  differs from profile  10  in  FIG. 3  and profile  11  in  FIG. 4  in that the base curve  110  is positioned at a different height relative to the registry groove  6 . 
     FIG. 6  is a cross-sectional view of the key blank illustrating a profile  10  in Section C and profile  51  in Section C′. Profile  51  differs from profile  50  in that groove  132  projects deeper into the side of the blank than groove  132 ′ of  FIG. 3 . 
     FIG. 7  is a cross-sectional view of a key blank illustrating profile  10  on Section C of the key blank and profile  62  on the other side in Section C′. Profile  62  differs in that groove  141  projects into the side of the blank at a different straight angular shape than groove  131  in  FIG. 2 . 
     FIG. 8  is a further illustration of a cross-sectional view of a key blank illustrating a profile  23  in one side of the bitting area of the blade in Section C and profile  71  on the other side of the blade in Section C′. In Section C the base curve  110  is the same as shown in  FIG. 2 , however the curved groove  123  is changed to a curved ridge  123 ′ and the curved ridge  122  is changed to a curved groove  122 ′. These changes produce a different sub-grouping of the secondary families of the key blank hierarchical structure. In Section C′ of the blank in  FIG. 8  there is no groove in the area  132 ″ and there is a straight angular groove  135 . The straight angular grooves  131 ,  133  and  135  determine the individual position of the blank in the hierarchical structure. 
     FIG. 9  is a cross-sectional view of another variation of the key blank showing profile  31  in Section C and profile  81  in Section C′. Base curve  210  of profile  31  determines the location of partial circular curves  221 - 227  that extend as curve grooves  224  or curve ridges  221 ,  222 ,  223 ,  225 ,  226 ,  227  along the length of the key blade. Secondary families of the curved shapes are determined by variations in the base curvilinear shape. The subgroups of these secondary families are determined by the presence of either curved ridges or curved grooves and by the position of the base curvilinear shape up or down the side of the blank in relation to the registry groove  6  in Section A. In profile  81  there are only two cut grooves  151  and  153  showing further possible variations. 
     FIG. 10  is an illustrative diagram of a simple three-level hierarchical structure of keyways. A key blank that is configured to fit exactly in the top most key section  1000  is structured to also fit in all of the subordinate keyways. A key blank that is configured to fit exactly in one of the secondary level keyways, e.g.,  1300 , will also fit into all of the subordinate keyways  1310 ,  1320 ,  1330  of secondary level keyway  1300 , but not into any of the third level keyways  1110 ,  1120 ,  1130  of secondary keyway  1100  or  1210 ,  1220 ,  1230  of secondary keyway  1200 . The keys that will fit in the lowest level of the keyways Level  3  will not fit in any of the higher level keyways. This fit or not fit determination is accomplished not by the bitting at the top of the keys as is typical in prior art (although such could be used to further provide hierarchical structure) but, is provided by the grooves extending along the sides of the key blank as described above. 
     FIG. 11   a  shows a cylinder lock  300  embodying aspects of the present invention into which a key  330 , such as a key described above, is inserted in the keyway. Key  330  includes a bow  332  and a blade  334 . The cylinder lock  300  may be part of a lock assembly further including a cylinder housing rotatably supporting the cylinder  300  as well as tumbler pins, sliders, and other mechanisms (not shown) for preventing rotation of the cylinder within the cylinder housing until a properly configured key or other instrument is inserted into the keyway to operate the lock. 
     FIG. 11   b  shows a cross-section of the key blade  334  inserted into the keyway  302  of the cylinder  300 . Key blade  334  has a cross-section similar to that shown in  FIG. 9 , although key blades having cross-sections such as those shown in  FIGS. 2-8  may also be used. As described above, the key blade  334  includes a first section near a bottom edge  335  of the blade having a groove  336  formed longitudinally along at least a portion of the blade  334 . Groove  336 , as described above, may be provided for registry purposes. A second section of the blade  334  includes a groove  338  formed longitudinally along at least a portion of the length of the blade. A third section extending to the top edge  337  of the blade  334  includes, on one side, straight angular grooves  340 ,  344  extending longitudinally along at least a portion of the blade and, on the opposite side, curved grooves and ridges  342 ,  346  formed longitudinally along at least a portion of the length of the blade. As described above, in the preferred embodiment, one side of the third section of blade includes only straight, angular, or rectangular grooves while the opposite side includes only curved grooves and ridges. 
     FIG. 11   c  shows an end view of the cylinder  300  without the key blade  334  inserted therein. The cylinder  300  includes the keyway  302  having an open bottom end  304  and a closed top end  306 . A first section of the keyway  302 , adjacent the bottom end  304 , includes a ridge  308  conforming to the groove  336  formed in the first section of the blade  334 . A second section of keyway  302  includes a ridge  310  conforming to groove  338  formed in the second section of the blade  334 . The third section of keyway  302 , extending to the top end  306  of the keyway, includes, on one side thereof, ridges  312 ,  316  conforming to grooves  340 ,  344 , respectively, formed on one side of the third section of the blade  334  and, on the opposite side of the keyway, ridges  314  and grooves  318  conforming to the grooves  342  and ridges  346 , respectively, formed on the opposite side of the third section of the blade  334 . In a preferred embodiment, ridges  312  and  316  formed on one side of the third section of the keyway  302  have only a straight angular shape (as shown) or a straight rectangular shape. The grooves  318  and ridges  314  formed on the opposite side of the keyway  302  in the third section have only curved shapes. 
     FIGS. 12   a  and  12   b  show an end view of a cylinder  300 ′ having a keyway  302 ′.  FIG. 12   a  shows the cylinder  300 ′ with a key blade  334 ′ inserted into the keyway  302 ′. The key blade  334 ′ is substantially identical to the key blade  334  shown in  FIG. 11   b , except that the groove  340 ′ formed in the third section of the key blade  334 ′ has a slightly higher position relative to the bottom edge  335  than the groove  340  formed in the key blade  334 . Similarly, the ridge  312 ′ extending into the keyway  302 ′ conforms to the groove  340 ′ formed in the third section of the blade  334 ′ and is positioned higher along the keyway  302 ′ than the ridge  312  of the keyway  302  shown in  FIG. 11   c.    
     FIGS. 13   a  and  13   b  show an end view of a cylinder  300 ″ having a keyway  302 ″.  FIG. 13   a  shows the cylinder  300 ″ with a key blade  334 ″ inserted into the keyway  302 ″. The key blade  334 ″ is substantially identical to the key blade  334  shown in  FIG. 11   b  and the key blade  334 ′ shown in  FIG. 12   a , except that the groove  340 ″ formed in the third section of the key blade  334 ″ has a slightly higher position relative to the bottom edge  335  than the groove  340 ′ formed in the key blade  334 ′ and the groove  340  formed in the key blade  334 . Similarly, the ridge  312 ″ extending into the keyway  302 ″ conforms to the groove  340 ″ formed in the third section of the blade  334 ″ and is positioned higher along the keyway  302 ″ than the ridge  312  of the keyway  302  shown in  FIG. 11   c  or the ridge  312 ′ of the keyway  302 ′ shown in  FIG. 12   b.    
     FIG. 14   a  shows the cylinder  300  (as shown in  FIG. 11   b ). As described above and shown in  FIG. 11   c , keyway  302  of cylinder  300  includes a first ridge  308  in the first section near the bottom  304  of the keyway, a ridge  310  in a second section of the keyway, and in a third section of the keyway extending to the top end  306 , ridges  312  and  316  formed on one side of the keyway and curved grooves  318  and ridges  314  formed on the opposite side of the third section of the keyway.  FIG. 14   a  shows a key blade  350  inserted into the keyway  302 . Key blade  350  is essentially identical to key blade  334  shown in  FIG. 11   b  and includes a groove  336  in a first section, a groove  338  in a second section, groove  344  formed in one side of a third section of the blade and grooves  342  and ridges  346  formed in the opposite side of the third section of the blade. Blade  350  differs from blade  334  in that, instead of having a groove  340  in the third section conforming to ridge  312  of the keyway  302 , key blade  350  includes an enlarged groove  352  that accommodates the ridge  312  with excess room to spare. 
     FIG. 15   a  shows the key blade  350  inserted into the keyway  302 ′ of cylinder  300 ′, and  FIG. 16   a  shows the key blade  350  inserted into the keyway  302 ″ of cylinder  300 ″. As can be seen in the figures, the enlarged groove  352  formed in the key blade  350  accommodates all of the ridges  312 ,  312 ′,  312 ″. Accordingly, key blade  350  is a master key blade that will operate any of the cylinders  300 ,  300 ′,  300 ″. 
   A top edge of the blades  334  and  350  may have biting formed therein for positioning tumblers within the cylinder for operating the lock. 
     FIGS. 14   b ,  15   b , and  16   b  show lock cylinders  300 ,  300 ′,  300 ″, respectively, with a lock bypassing instrument  360  inserted into the keyway of each of the cylinders. More specifically, the instrument  360  includes a blade-like projection adapted to be inserted into the keyway, wherein the projection is sufficiently thin to fit into the keyways between the ridges of the keyway. The instrument  360  may have other features formed therein, such as bitting for positioning tumbler pins and a side projection for operating a slider within the keyway. Instrument  360  may thus be inserted into the keyway  302 ,  302 ′,  302 ″ and rotated to operate cylinder  300 ,  300 ′,  300 ″, respectively. Thus, the instrument  360  may be used to illicitly bypass the security provided by the unique combination of grooves and ridges formed in the keyway which is intended to be opened only by a properly conforming key having conforming grooves and ridges. The illustrated embodiment is exemplary. The instrument used to open the lock may take forms different from that shown in  FIGS. 14   b ,  15   b , and  16   b  and may comprise two or more pieces used in conjunction to open the lock as opposed to the single integrally-formed device (instrument  360 ) shown. 
   Further variations and modifications of this invention will be apparent to those with ordinary skill in the art of keys and master keying for mechanical locks.