Abstract:
A mechanical key and lock cylinder with mechanical bittings include an electronic access control feature, with minimal modification and without affecting or interfering with the mechanical function of the key and cylinder. A small, low-profile memory cell is embedded in a recess or later hole through the key, with one cell terminal grounded to the key and the other having a contact extension. When the key is inserted into the keyway of the cylinder plug, the ground connection is made with the cylinder and the memory cell contact extension engages a spring-loaded contact of a connector unit which extends from the cylinder plug. An insulated wire carries the conductive path out of the lock cylinder. The key remains of very low profile, and the cylinder plug is modified only by a small longitudinal bore from front to rear. Existing mechanical locks and cylinders can easily be retrofitted with the electronic access control feature. In another embodiment the key has its contacts on one or both sides of the key blade rather than at the shoulder of the key head. The memory cell device in or on the key head can include a microprocessor, battery and read/write memory.

Description:
BACKGROUND OF THE INVENTION 
   This application is a continuation of application Ser. No. 09/595,388, filed Jun. 14, 2000, now U.S. Pat. No. 6,927,670, which was a continuation-in-part of application Ser. No. 08/705,843, filed Aug. 30, 1996, now U.S. Pat. No. 6,552,650, which was a continuation-in-part of application Ser. No. 08/342,846, filed Nov. 21, 1994, now U.S. Pat. No. 5,552,777, which was a continuation-in-part of application Ser. No. 07/836,206, filed Feb. 14, 1992, now U.S. Pat. No. 5,367,295. 

   This invention relates to the use of existing mechanical locks with mechanical tumbler types of cylinders for electronic access control. 
   A number of access control systems have existed incorporating electrically operated locking devices with decision-making electronics for permitting access housed within the lock&#39;s trim, such as Touchcode system manufactured by Yale Electronics of Charlotte, N.C., Nova System manufactured by Kaba of Southington, Conn., and Solitaire System manufactured by Mar-lock of Chicago, Ill. Some of these access lock systems employ keypads, some cards, some purely electronic, magnetic or optic keys, and some employ mechanical keys equipped with electronic circuitry. 
   For the benefit of the current invention, distinction must be made between the purely electronic, magnetic or optical keys, mechanical keys, and mechanical keys equipped with electronic, magnetic or optical features. 
   A key comprised of purely electronic circuitry, magnetic or optical data storage and identification for access is an electronic key. In their use, the circuitry or recorded data is transferred to the reader means or reader recognizes the pattern held by the key optically. This key does not carry any mechanical cut configuration which is critical for granting access. These types of keys can be found in U.S. Pat. Nos. 3,797,936, Dimitriadis, granted Mar. 19, 1974; 4,209,782, Donath et al., granted Jun. 24, 1980; 4,257,030, Bruhin et al., granted Mar. 17, 1981; 4,620,088, Flies, granted Oct. 20, 1986; 4,659,915, Flies, granted Apr. 21, 1987; 4,789,859, Clarkson et al., granted Dec. 6, 1988. Mechanical keys are keys which activate a mechanical device through direct contact with the interpreting device, the tumblers. Based on the depth and placement configuration of the cut&#39;s meeting the tumblers and creating the proper alignment of such tumblers, access is granted. In most cases, once the proper alignment is established, the keyholder is able to turn the key to lock and unlock the locking device. However, in some cases, a push or pull action may be necessary for the locking and unlocking of the locking device. The aforementioned tumblers can be pin tumblers, lever tumblers, disk tumblers, rotary disk tumblers, or slider tumblers. Examples of mechanical keys may be found in U.S. Pat. Nos. 480,299, H. G. Voight, granted Aug. 9, 1892; 550,111, H. B. Sargent, granted Nov. 19, 1895; 564,029, H. B. Sargent, granted Jul. 14, 1896; 3,208,248, Tornoe, granted Feb. 6, 1963; 4,723,427, Oliver, granted Feb. 9, 1988; 4,732,022, Oliver, granted Mar. 22, 1988; 4,823,575, Florian et al., granted Apr. 25, 1989. 
   A mechanical key equipped with electronic circuitry, magnetic or optical data storage or optically recognizable features can be found in U.S. Pat. Nos. 3,733,862, Killmeyer, granted May 22, 1973; 4,144,523, Kaplit, granted Mar. 13, 1979; 4,326,124, Faude, granted Apr. 20, 1982; 4,562,712, Wolter, granted Jan. 7, 1986; 4,663,952, Gelhard, granted May 12, 1987; and 4,686,358, Seckinger et al., granted Aug. 11, 1987. See also Patents Nos. 5,003,801, Stinar et al., 4,998,952, Hyatt et al., 5,131,038, Puhl et al., 5,140,317, Hyatt et al. and 5,245,329, Gokcebay. Keys shown in some of these patents carry the secondary element whether it is an electronic circuitry or some other type of coded data or recognizable pattern, in addition to its mechanically operating feature as described in purely mechanical keys. In some instances, both mechanical and non-mechanical features of the key are used simultaneously for granting access and in some cases, these features are used independently. None of the patents discloses a key with built-in or built-on modular, self-contained, off-the-shelf memory cell formed in a can-like container as manufactured, for example, by Dallas Semiconductor. 
   The current invention relates to the conversion of mechanical lock cylinders and keys for electronic use without altering their mechanical functionality, as well as to a simple cylinder and a key fitted with electronic components, particularly to a key fitted with a self-contained memory unit in the key head, with one wire bus connection to a contact for connection to a lock or reader. As mentioned above, keys and cylinders employing other electronic or other non-mechanical features, as well as mechanical features, exist. In these existing types of systems, a keyholder will insert his/her key carrying electronic circuitry with contact means into the key receiving cylinder employing a matching contact means and, upon this insertion and sometimes insertion and turning, a contact will be made with the reader unit transferring the access information into the lock&#39;s decision making unit. This decision making unit is usually housed within the lock&#39;s trim plate. Upon the decision to grant access, the unit will electrically unlock the locking mechanism or allow the key to turn and retract the latch bolt of the lock. 
   These systems employ complicated and expensive circuitry and contact means, thus requiring special manufacturing of both cylinder and key. 
   The objective of the current invention is to provide a simple method of conversion that applies to any mechanical key and cylinder combination for their use in electronic access control systems; and to the mechanical key itself, efficiently fitted with a memory cell in a standardized Dallas Semiconductor can-like container, and this can be more than a memory cell and may include microprocessor, battery, read/write memory, etc. 
   A simplified approach is taken to the reader and the key connection by the present invention described below. In a preferred embodiment, the existing lock cylinders and keys are simply modified (or the same type of lock and key are OEM fitted) to become a part of an electronic access control lock while still maintaining their mechanically operating status. In the case of the key itself, it can take several forms as to the contact for the one wire bus connection, but in each case the key has a memory cell of the type described, fitted into the key head. 
   SUMMARY OF THE INVENTION 
   The Key 
   The mechanical key is fitted with a memory cell employing one wire bus communication protocol such as ones made by Dallas Semiconductor models DS1990, DS1991, DS1992, DS1993 and DS1994, having a conductive metal casing with an isolated data terminal. These cells are fitted into the key&#39;s head area by opening a hole on the key&#39;s head the same size as the cell&#39;s diameter for a tight fit contact. In another preferred embodiment, the hole for the memory cell may not be drilled all the way through, leaving metal at the bottom of the cavity for better contact. Due to the small size of the cell, there is adequate space in the key&#39;s bead for its normal mechanical functions and other capabilities, i.e. shoulder stops, key-ring hole, etc. Preferably a plastic cover is included over the key&#39;s head. The key can also be made as an OEM product, formed with the hole or recess, fitted with the memory cell and then enveloped with the plastic cover. 
   By inserting the memory cell into the key, the ground contact between the cell and the key is established. The data communication is provided by a small metal probe or contact extension contacting the other terminal or data end of the cell and extending toward the key cut, most of it covered by the outside plastic cover. While one end of this probe is making contact with the data end of the cell, the other end lies generally flush with the key shoulder (which limits movement of the key into the lock cylinder). The probe is within the outside cover but in such a way that upon insertion of the key into the key plug it will come in contact with the isolated contact located on the receiving plug. In another embodiment, the memory cell or cell unit carrying a microprocessor is not grounded to the metal of the key, but two isolated conductors extend to a position on the key where two contacts are located, still in a one wire bus connection. The contact or contacts can be either at the key shoulder, facing toward the cylinder plug as described or on the key blade, on one or both sides of the blade. The probe can be spring loaded in the key while the receiving contact is fixed, or both could be spring loaded or otherwise biased. 
   The Isolated Contact 
   This unit consists of a spring-loaded contact, preferably 22 gauge ordinary electrical wire and heat shrink tubing. The spring-loaded contact is the type that is commonly used in the testing of electronic circuitry like those made by Interconnect Devices, Inc. The outside diameter of this contact is about 0.054″. The heat shrink tubing is also commonly used and available for insulation purposes. In the preferred embodiment, the wire is soldered to the back end of the contact, then they are both inserted into the heat shrink tubing leaving a small portion of the contact exposed. In another preferred embodiment, a female connector may be soldered to the back end of the contact to facilitate hook-up to the circuitry. The unit is then heated and the heat shrink tube insulates the contact and the wire creating the connector unit. The unit is now ready to be inserted into the cylinder plug. In another preferred embodiment the isolated contact is a solid piece of wire insulated by heat-shrink tube or other type of insulating material. In automotive applications the isolated contact may comprise a flat wire as a leaf spring, biased inward toward the keyway and located in a housing in front of the cylinder plug (rather than in the plug itself), as in some General Motors vehicles. 
   The Cylinder Plug 
   In accordance with one preferred embodiment of the present invention, a small hole is drilled along the length of the cylinder plug at the side of its keyway, without interfering with its mechanically operating pins, wafers, disks, side-bars or sliders, etc. The isolated contact unit is then inserted and secured into the above-mentioned hole. The spring loaded tip of the isolated contact unit extends from the plug surface approximately 0.015″ to establish contact with the key&#39;s probe. The other end of the isolated contact unit carrying communication from the key is sent to a processor board for processing of the data. The body of the plug, cylinder and lock body thereof, serves as the ground part of the communication. This comprises a single-wire bus communication protocol. 
   In another preferred embodiment, the lock cylinder may be of a high security type, such as ones manufactured by Medeco Security Locks, Assa, Schlage Primus line, etc. High security lock cylinders generally employ secondary locking principles to achieve further security. The employment of these principles does not interfere with the present invention nor the present invention interfere with the above mentioned additional locking principles, making the method applicable to virtually any type of mechanical locking cylinder available in the marketplace today. There is also no interference with the cylinder&#39;s cam unit, allowing normal mechanical functionality. 
   Upon insertion of the key into the cylinder plug, the probe makes contact with the connector unit located on the plug and transmits the data. These cell units are available with pre-programmed memory carrying identification number data, as well as read and write memory, allowing many applications, such as cells carrying data about the keyholder such as name, PIN number, access code, biometric template (e.g. fingerprint, retina scan, voice print), etc. The memory cell preferably is password protected, so that only authorized persons can have access to the data contained in the memory cell. 
   In some embodiments the memory cell contains a microprocessor, battery and read/write memory, providing encryption capabilities, other security identification, and individualized keyholder preferences such as, in automobile applications, seat, mirror and radio adjustments, by interacting with a processor and data bank in the vehicle. Additional functions that may be achieved include radius of travel, speed of travel, distance of travel, times of travel, etc. For example, a parent can regulate when a child can drive, how far and at what speed, etc. 
   No complex key blank, lock cylinder or plug manufacturing is necessary in principal embodiments of the present invention, which use keys and cylinders manufactured by all major lock manufacturers, i.e. Schlage, Yale, Corbin, Russwin, Arrow, Assa, Sargent, Medeco, Falcon, etc. In another embodiment one or two key contacts are found on the sides of the key blade, and this can be similar to the automotive keys made by Strattec Security Corporation (Milwaukee, Wis., U.S. Pat. No. 4,148,372). In that case, the lock cylinder is fitted with a front cover which reads the blade side contacts. 
   When the key is used for access control purposes, it may not have the mechanical configurations necessary to operate the lock cylinder in which it is being inserted. It may, however, be able to operate other locks within the facility where access control or high security is not required, and the keyholder is allowed to enter by using the mechanical feature of his/her key. The locks that are fitted with the access control system will still have the mechanical by-pass capability. These locks may, for example, be keyed to the grand master key. This feature can be handy if the electronics of the lock fail. In another embodiment the lock cylinders will all be fitted with secondary locking mechanisms that usually exist in high security cylinders such as side bittings that operate a locking side bar. In these types of systems generally all the side bittings on all of the operating keys are the same; therefore, the key will operate these side bittings mechanically while also providing electronic access to the cylinder. The regular tumbler bittings may be used for access to purely mechanical cylinders. In another embodiment the key may not have any mechanical bitting configuration but a shape that will allow an insertion to the receiving device. In this case the key will only be used as an electronic access device. The key may have a bump or a dimple or some other form of locator/registry feature that may also act as a key retainer once inserted and turned (if design requires turning). 
   Since the key contains both a memory cell containing access control data and mechanical bittings, it can be used for accessing both high and low security areas. The mechanical bittings will allow the user to access areas where time and date control for access is not required, thus making it a low security area, and the electronically stores access control data can be used in locks (areas) employing time and date control, thus making it a high security area. 
   The above aspects relative to higher and lower security points and biometric featured encoded on the key are similar in some respects to the system disclosed in co-pending application Ser. No. 343,663, filed Apr. 27, 1989, now U.S. Pat. No. 5,245,329 and the disclosure of that application is incorporated herein by reference. 

   
     DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a front view of a mechanical mortise cylinder fitted with the conversion means. 
       FIG. 2  is a perspective view of the same cylinder. 
       FIG. 3  is a rear view of the same cylinder with the wire ready for connection. 
       FIG. 4  shows a side view of a mechanical key-in-knob type cylinder fitted with a conversion means. 
       FIG. 5  shows an assembled connector unit. The hole  12  is equipped with the connector unit  13 . 
       FIG. 6  shows a mechanical key fitted with the memory and contact means. 
       FIG. 7  shows a picture of the memory cell employing one wire bus communication protocol. 
       FIG. 8  is a view showing a slightly modified form of key, similar to the key of  FIG. 6  which includes secondary bittings. 
       FIG. 8A  is a profile (top) view of the key of  FIG. 8 . 
       FIG. 8B  is a side view of a key again similar to  FIG. 6  but having a data contact in a slightly different position. 
       FIG. 8C  is a profile view of the same key. 
       FIG. 8D  is a view similar to  FIG. 8A  but showing a key with both data and ground contacts positioned at the key shoulder. 
       FIG. 8E  is a view similar to  FIG. 8D  but with a variation on the contact position. 
       FIG. 8F  is a perspective view of a key with its data connection components. 
       FIG. 8G  shows a key similar to  FIG. 8B  but without the usual bittings. 
       FIG. 8H  is a top view of a key having two memory cells or a memory cell and another device. 
       FIG. 9  is a perspective view of a key which may be an automotive key, with an isolated data contact on the side of the key blade. 
       FIG. 9A  is a perspective view of a key similar to  FIG. 9 , but with two isolated contacts on the key blade. 
       FIGS. 10 ,  10 A,  10 B and  10 C are perspective views of reversible keys having contacts in different positions for reversible function, including contacts on the shoulders of the keys and contacts on the key blades. 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
   In the drawings,  FIG. 1  shows the front view of a mortise type cylinder  10 . The cylinder plug  11  contains a hole  12  on The side of its keyway in such distance from the keyway where it does not interfere with the pinholes  14  and pins  15  working inside the pinholes  14 . A connector unit is in the hole  12 , electrically insulated from the metal of the plug. 
     FIG. 2  shows the same cylinder in perspective, including the connector hole  12  inside the cylinder plug, and the connector unit  13 . 
     FIG. 3  shows the rear view of the cylinder  10 , with the cam/tail piece  17  attached to the cylinder plug by screws  18 , and the rear end of the connector hole  12  with the wire end of the connector unit  13 . A wire  16  extends from the connector unit. 
     FIG. 4  shows in perspective a key-in-knob type cylinder equipped with the connector means. The plug  21  inside the cylinder  20  (the pin-holding portion is shown) is equipped with the connector hole  12  and the connector unit  13 . The tail/cam piece  19  is attached to the plug  21 , with the wire end of connector unit  13  coming out of the rear end of the cylinder  20 . 
   In all types of cylinders, the wire end of the connector unit  13  comes through the plug unit, therefore there is no interference when the cylinder plug turns by use of purely mechanical action. The connector unit turns with the plug, causing no interference to its mechanical operation. 
     FIG. 5  shows the assembled connector unit  13 . The spring loaded connector head  37  is soldered to the wire  16  at  39 . They are then housed by the insulative heat shrink tube  35 . When covered by the heat shrink tube  35  there is sufficient space at the connector head  37  for making contact, i.e. the connector head extends out from the tube  35  and from the plug, when installed. 
     FIG. 6  shows mechanical key  50  having a mechanical cut configuration  51  fitted with a memory cell  52  into its cavity  55 . The outside plastic cover  54 , shown in dashed lines, contains the contact probe or contact extension  53  which upon closure of the cover over the key makes contact with the memory cell  52 . The other end or tip  56  of the probe  53  is lined up with the shoulder of the key  57 . When the key  50  is inserted into the receiving cylinder, the key-probe  53  makes contact with the cylinder connector unit, i.e. with the spring loaded connector head  37 . 
   Instead of being a part of the plastic cover, the contact probe  53  can be permanently secured to the data connection terminal (e.g. by soldering) of the memory cell  52 . 
     FIG. 7  shows the single wire bus type memory cell  52 . Item  70  is the ground connection and item  71  is The data connection, the two terminals of the cell. This comprises a single-wire bus communication protocol. 
     FIGS. 8 and 8A  show a key  75  which is conceptually the same as the key shown in  FIG. 6 . The key  75  has a forward contact  56  generally from the shoulder of the key and positioned to engage on a mating contact of a lock cylinder or reader, and the key also has a blade  76  with a key cut configuration  78  and optional secondary cut configuration  79 . The data contact  56  at the shoulder  80  of the key extends back via a conductor  53  to make contact with the data side  82  of a memory cell  84 , which may be a memory cell as made by Dallas Semiconductor, including the models noted above, or which can be a more complex device, with microprocessor, battery, read/write memory, etc., often called an iButton. A plastic cover of the key head is shown at  86 , and this can include a loop  88  for a key ring with the memory cell/iButton  82  nested closely against the metal of the key head  90 , preferably closely fitted within a recess or hole in the metal key head. The key head  90  can be of slender configuration, a comfortable size for gripping and turning in a lock, as shown in  FIG. 8A . In a preferred embodiment the plastic cover  86  has a dished-in configuration as shown in  FIG. 8A , which tends to be comfortable to use. 
     FIGS. 8B and 8C  show a key  75   a  which is very similar to the key  75  of  FIG. 8  but with a data contact  56   a  in a different position on the key shoulder  80 . In this case the contact  56   a  is located radially outwardly from the rotational axis of the key, for making contact with a mating contact which is farther removed from the key slot. As shown in  FIG. 8C , this contact  56   a  can be centered relative to the key blade, if desired. It could also be offset to left or right if desired. 
     FIG. 8D  shows a similar key to that of  FIGS. 8 and 8A , but with two contacts  56   b  and  56   c  on the shoulder  80  of the key  75   b , rather than a single data contact. This can be in the case where the memory cell or self-contained microprocessor device as described above is not grounded to metal of the key, such as where the key is not of conductive metal or where the plastic casing  86  alone is employed to retain the memory cell or to provide a dedicated ground contact or simply as a design choice. Thus, two conductors are then needed for contact with a lock or keyreader, one connected to the data side of the memory cell and one to the ground side, thus the two contacts  56   b  and  56   c.    
     FIG. 8E  shows a key  75   c  with a further variation at the two contacts, now identified as  56   d  and  56   e , are at one side of the key shoulder  80 . These contacts can either be at the left side or the right side, for mating with appropriately positioned contacts in a lock cylinder or other keyreader.  FIG. 8F  shows a key  75   d  with a stamped spring data contact  89  and pin  89   a . The spring data contact  89  slips over the pin  89   a  with a tight press fit and provides spring action so that the pin is biased against the receiving contact. The spring contact  89  also provides positive pressure against the memory cell  84  for good contact. The key is encapsulated by the plastic cover  86  which may be two pieces bonded together to create the housing. 
     FIG. 8G  shows a key  75   e  which is purely an electronic access key, except that the key has a blade  76   a  that can be used for turning the plug of a lock cylinder. The blade  76   a  is without mechanical bittings but with a shape that will allow insertion into a receiving device. The key blade  76   a  has a bump or dimple  76   b  or some other form of locator or registry feature that may also act as a key retainer once the key  76   e  has been inserted and turned, in key receivers requiring turning. 
     FIG. 8H  shows in top view a key  75   f  which has two memory cells/iButtons  84 ,  84   a , and these may be positioned back to back in the key head as shown. The second cell  84   a  could alternatively comprise a battery, for providing greater battery power. However, in the configuration shown, two memory cells preferably are secured in or on the key head  90   a , and the data sides of these cells are contacted by stamped leaf spring contacts  89  in the manner discussed previously. Spring contacts  89   a  extend into position to engage with a lock contact, as also discussed above.  FIG. 8H  illustrates that the invention contemplates two (or possibly more) memory cells or other similarly-sized can-like devices in or on the key head when this is needed or will provide better performance, further functions, etc. 
     FIG. 9  shows another form of key  92 . The key  92  again has a key head  94 , blade  95  and mechanical key cut configuration  96 . A memory cell or iButton device  84  is secured to the key head, preferably with the ground side of the two-pole can grounded against the metal of the key. In this case, however, the data contact is not positioned to project from the key shoulder, but instead is located in the key blade at  98 , preferably just back from the end of the key cuts  96  toward the head. Such a data contact is generally as shown in U.S. Pat. No. 4,148,372 referenced above. However, that patent describes the similarly-located contact as a resistance element, whereas in the present invention the element  98  is a data contact. An isolated conductor  100  leads from the contact  98  back to the data side  102  of the memory cell or iButton. As in the earlier described keys, the key  92  has a plastic covering  104  over the key head. 
     FIG. 9A  shows a variation of  FIG. 9 , wherein the key blade  95  has two contacts  98   a  and  98   b  for making conductive contact with a lock cylinder apparatus or key reader. As above, this is usually for the case where the memory cell or iButton  84  is not grounded to conductive metal of the key, but rather has a data side conductor  100   a  and a ground side conductor  100   b , both isolated and connected to the contacts  98   a  and  98   b . In some instances the contacts  98   a  and  98   b  may be the data connection of two different memory cells (as in  FIG. 8H ) providing different functionality, or while  98   a  is providing data connection,  98   b  may provide connection to a watch-type battery (similar size as the memory cell) to supply additional power. 
   The keys  92  and  92   a  shown in  FIGS. 9 and 9A  generally are for automotive use. For that purpose, the automobile ignition may be fitted with a shroud (not shown) which is not actually part of the lock cylinder but which is slightly back (toward the driver) from the lock cylinder and positioned to make contact with the data contact  98  (or  98   a ,  98   b ). The data contact  98  can be exposed at only one side of the key blade or at both sides, for reader contact redundancy. Note that the two-contact version of the key  92   a  can be modified such that one contact  98   a  is on the left side of the blade and the other contact  98   b  is on the right side of the blade. This is determined by the design of the reader element, whether it is desired to have both reader contacts on one side or one on each side, etc.  FIG. 9  shows a plastic insulative insert  99  for the key, preferably press-fit into a hole or recess  99   a  in the key and within which the contact  98  is embedded or contained and extends out as a contact. A flat spring conductor  99   b  connects the data side of the memory cell  84  to the back end of the contact  98 . 
     FIGS. 10 ,  10 A,  10 B, and  10 C show additional automotive keys  105 ,  105   a ,  105   b  and  105   c , in this case reversible keys that can be used in either of two 180°-opposed orientations. These drawings show schematically several different schemes for location of the contact or contacts for communication to and from the memory cell (iButton)  84  contained in the key head. As shown in all these schematic drawings, the key cuts  106  are identical on both sides of the key blades  107  and thus the keys are reversible. In  FIG. 10  identical data contacts  108  are located in similar positions on the shoulders  110  of the symmetrically-shaped head. Each data contact is the same, being connected to the data side of the memory cell device  84  (in the claims, the term “memory cell” is intended to refer to any of the devices described above, including an iButton having microprocessor, battery, read/write memory, etc.). 
   In  FIG. 10A , both a data contact  108  and a ground contact  111  are located at each opposing shoulder  110  of the reversible key  105   a , in similar and symmetrical positions. The two contacts are provided for cases similar to those described above, where it is not desired to ground the ground side of the memory cell  84  to conductive metal of the key, or one may be providing data and the other battery power from an additional cell similarly shaped as an iButton or a watch battery. Alternatively, two memory cells may be employed and the contacts  108 ,  111  may provide connection to these cells separately. Compression springs  113  are shown for urging the contacts  108 ,  111  into secure electrical contact with the data reader. 
     FIGS. 10B and 10C  schematically show similar reversible keys  105   b  and  105   c , but in these drawings the data contacts are shown on the key blade  107   b ,  107   c , similar to the keys of  FIGS. 9 and 9A .  FIG. 10B  shows a single data contact  112  in the key blade and this can be mounted in a manner similar to what is shown in  FIG. 9 , with an isolated conductor  114  (see  FIG. 10C ) leading to the data side of the memory cell  84 , making contact via a flat spring conductor  99   b . As in  FIG. 9 , the conductor(s)  114  preferably are contained within a plastic insert  99 . The contact  112  is at both sides of the key blade  107   b , protruding outwardly so as to be readable by a key reader contact, which can be mounted on an automotive lock cylinder as described above. In  FIG. 10B , a single isolated conductor  114  (not seen in  FIG. 10B ) is sufficient, with the contact  112  extending through the thickness of the key blade and thus providing two identical contacts for the reversible key. 
     FIG. 10C  merely shows that the contacts on the key blade  107   c  can include both a data contact  112   a  and a ground contact  112   b , for the same situation described above relative to  FIGS. 9A and 10A . Again, these contacts are provided on both sides of the reversible key blade, a pair of isolated conductors  114  being provided for these contacts. 
   The above described preferred embodiments are intended to illustrate the principles of the invention, but not to limit its scope. Other embodiments and variations to this preferred embodiment will be apparent to those skilled in the art and may be made without departing from the spirit and scope of the invention as defined in the following claims.