PATENT DOCUMENT

Publication Number: US-8477049-B2
Application Number: US-47963109-A
Country: US
Kind Code: B2

Title: Efficiently embedding information onto a keyboard membrane

Abstract:
Methods and systems for efficiently embedding information in a keyboard membrane. Information can be embedded in the keyboard membrane by integrating an information embedding circuit with a switch matrix used to identify location of a key press event. The information is embedded by either hardwiring a column to a selected row, or a row to a selected column. In order to access the embedded information, the row (column) is asserted resulting in the hardwired column (row) to also be asserted. The identification of the asserted column (row) is used to point to the embedded information.

Claims:
What is claimed is: 
     
       1. A system for embedding information in a keyboard membrane incorporated in a keyboard, comprising:
 a switch matrix comprising a plurality of column conductors overlaid with a plurality of row conductors; 
 an information embedding circuit integrated with the switch matrix, wherein the information is embedded in the keyboard membrane by permanently connecting a selected one of the plurality of row conductors with an information embedding column conductor, wherein the information embedding circuit is used only during an initialization of the keyboard and is disabled after the keyboard initialization is successfully completed, wherein: 
 the embedded information is accessed by: 
 asserting the information embedding column conductor; and 
 causing the selected one of the plurality of row conductors to be asserted based upon the assertion of the information embedding column conductor. 
 
     
     
       2. The system as recited in  claim 1 , wherein the embedded information is further accessed by:
 identifying the asserted row conductor; and 
 using the identified asserted row conductor to retrieve the embedded information. 
 
     
     
       3. The system as recited in  claim 1 , wherein the information embedded in the keyboard membrane is an indication of a keyboard type. 
     
     
       4. A system for embedding information in a keyboard membrane incorporated in a keyboard assembly, comprising:
 a switch matrix comprising a plurality of column conductors overlaid with a plurality of row conductors; 
 an information embedding circuit integrated with the switch matrix, wherein the information is embedded in the keyboard membrane by permanently connecting a selected one of the plurality of column conductors with an information embedding row conductor, wherein the information embedding circuit is used only during a boot sequence of the keyboard and is disabled after the keyboard boot sequence is successfully completed; wherein, 
 the embedded information is accessed by: 
 asserting the information embedding row conductor; and 
 causing the selected one of the plurality of column conductors to be asserted based upon the assertion of the information embedding row conductor. 
 
     
     
       5. The system as recited in  claim 4 , wherein the embedded information is further accessed by
 identifying the asserted column conductor, and 
 using the identified asserted column conductor to retrieve the embedded information. 
 
     
     
       6. A method for embedding information in a keyboard membrane incorporated in a keyboard assembly, wherein the keyboard membrane includes at least a switch matrix comprising a plurality of column conductors overlaid with a plurality of row conductors and an information embedding circuit integrated with the switch matrix, comprising:
 wherein when the information embedding circuit includes an information embedding column conductor, then permanently electrically connecting a selected one of the plurality of row conductors with the information embedding column conductor, wherein when the information embedding column conductor is asserted, the selected one of the plurality of row conductors is also asserted; and 
 wherein when the information embedding circuit includes an information embedding row conductor, then permanently electrically connecting a selected one of the plurality of column conductors with the information embedding row conductor, wherein when the information embedding row conductor is asserted, the selected one of the plurality of column conductors is also asserted; 
 wherein the information embedding circuit is used only during keyboard assembly initialization and is disabled after keyboard assembly initialization is successfully completed. 
 
     
     
       7. The method as recited in  claim 6 , wherein the embedded information is accessed during boot up of the keyboard. 
     
     
       8. The method as recited in  claim 7 , wherein the embedded information is accessed by,
 asserting the information embedding column conductor; 
 asserting the selected one of the row conductors in response to the asserting the information embedding column conductor; 
 sensing which of the plurality of row conductors is asserted; 
 identifying the asserted row conductor; and 
 using the identified row conductor to access the embedded information. 
 
     
     
       9. The method as recited in  claim 8 , wherein the embedded information is accessed by,
 asserting the information embedding row conductor; 
 asserting the selected one of the column conductors in response to the asserting the information embedding row conductor; 
 sensing which of the plurality of column conductors is asserted; 
 identifying the asserted column conductor; and 
 using the identified column conductor to access the embedded information. 
 
     
     
       10. A keyboard membrane, comprising:
 a switch matrix; and 
 a non-binary type keyboard information embedding circuit integrated with the switch matrix used for embedding information in the keyboard, wherein the information embedding circuit is used only during a boot sequence of the keyboard and is disabled after the keyboard boot sequence is successfully completed; wherein 
 the information embedding circuit includes at least one of an information embedding column conductor and an information embedding row conductor; 
 information is embedded in the keyboard membrane by permanently connecting a selected one of a plurality of different conductors with the at least one of an information embedding column conductor and an information embedding row conductor; and 
 causing the selected one of the plurality of different conductors to be asserted based upon the assertion of the at least one of an information embedding column conductor and an information embedding row conductor. 
 
     
     
       11. The keyboard membrane as recited in  claim 10 , wherein the switch matrix comprises:
 an upper resin sheet; 
 a lower resin sheet; 
 a plurality of column contact pads each connected to one of a plurality of column conductors formed on an upper portion of the lower resin sheet, and 
 a plurality of row contact pads each connected to one of a plurality of row conductors formed on a lower portion of the upper resin sheet, wherein the column conductors and row conductors are overlaid one atop the other to form the switch matrix and are electrically isolated from each other. 
 
     
     
       12. The keyboard membrane as recited in  claim 10 , wherein the keyboard membrane has a reduced number of contact pads than would otherwise be required with a binary type information embedding circuit. 
     
     
       13. An apparatus for efficiently embedding information on a keyboard membrane, the keyboard membrane having at least a switch matrix formed of n column lines and m row lines each of which has a contact pad such that the switch matrix includes a number N contact pads, where N=m+n, comprising:
 a single contact pad; and 
 a single conductor line electrically connected to the single contact pad, wherein the single conductor line is electrically connected to at least one of the m row lines of the switch matrix, wherein when the single contact pad is asserted, then the contact pad associated with the at least one of the m row lines is determined to also be asserted; 
 wherein the single contact pad is used only during initialization of the keyboard and is disabled after keyboard initialization is successfully completed. 
 
     
     
       14. The apparatus as recite in  claim 13 , wherein the determination of which of the m row lines is asserted comprises: sensing all of the m row lines during a period of time that the single contact pad is asserted. 
     
     
       15. The apparatus as recited in  claim 14 , wherein the keyboard membrane includes at least N+1 contact pads. 
     
     
       16. The apparatus as recited in  claim 15 , further comprising: a data capture circuit arranged to capture information relating to the at least one of the m row lines determined to also be asserted. 
     
     
       17. A non-transitory computer readable medium including at least computer program code for accessing information embedded in a keyboard membrane during a keyboard initialization using an information embedding circuit having at least a cross connected first and second conductor lines, the computer readable medium comprising:
 computer program code for asserting a contact pad associated with the first conductor line only during keyboard initialization; 
 computer program code for determining an identity of the second conductor line cross connected with the asserted first conductor line; 
 computer program code using the identity of the cross connected second conductor line to access the embedded information; and 
 computer program code for disabling the information embedding circuit after the keyboard initialization is successfully completed. 
 
     
     
       18. The non-transitory computer readable medium as recited in  claim 17 , wherein the keyboard membrane includes a switch matrix. 
     
     
       19. The non-transitory computer readable medium as recited in  claim 18 , wherein the information embedding circuit is integrated with the switch matrix. 
     
     
       20. The non-transitory computer readable medium as recited in  claim 18 , wherein the embedded information is a list of keyboard types and wherein the identity of the cross connected second conductor line points to one of the list of keyboard types corresponding to the type of keyboard membrane.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to computer peripheral devices. More specifically, techniques for efficiently embedding information in a user input device, such as a keyboard membrane, are described. 
     2. Description of the Related Art 
       FIG. 1  is shows a conventional keyboard  100  having keyboard membrane  102 . Keyboard membrane  102  has a layered structure including a lower resin sheet  104  and an upper resin sheet  106 . Column contact pad(s) X 0 -X 4  and a lower wiring pattern(s)  108  are formed on an upper surface of the lower resin sheet  104 . Furthermore, row contact pad(s) Y 0 -Y 4  and an upper wiring pattern(s)  110  are formed on a lower surface of the upper resin sheet  106 . Taken together upper wiring pattern  110  and lower wiring pattern  108  form keyboard scanning matrix  112  having key  114  located at most of the row/column intersections. In this way, a user pressing a key (referred to as key press  116 ) will short together the respective row and column of scanning matrix  112 . In order to identify the character appropriate to the key being pressed, the relevant key location vis a vis scanning matrix  112  must be quickly and accurately determined. Therefore, in order to identify the location of the key being pressed, each of column contact pads X 0 -X 4  is sequentially asserted (i.e., by applying a voltage corresponding to either a HIGH or LOW value) for a period of time (column assertion period). During the period of time that a particular column conductor is asserted, each of the row contact pad Y 0 -Y 4  are sensed (during a row sensing cycle). Since pressing a key results in shorting a single row to a single column (at least during the period of time that a user has maintained key press  116 ), the contact pad associated with the row on which the key being pressed is located will also be asserted (i.e., either HIGH or LOW) for a period of time at least as long as the period of time that the column associated with the key being pressed is asserted. Therefore, the single row contact pad that is determined to be asserted during the row scanning operation is used with the identification of the asserted column to provide the co-ordinates in scanning matrix  112  corresponding to key press  116 . 
     Once the location of the key press  116  is determined, that information is passed to keyboard processor  118  by way of contacts  120  in tail  122 . Keyboard processor  118  uses the location information to read a character map  124  that maps a key pad location with a character. However, many of today&#39;s keyboards are capable of multiple configurations where different keys can map to different characters. For example, keyboard  100  can be configured to act as an ANSI type keyboard, a JIS type keyboard, or a ISO type keyboard. Therefore, during boot up, keyboard processor  118  must detect the type of keyboard being used, communicate this information to the system so that the system can apply the appropriate conversion to the keycodes subsequently sent by the keyboard providing the correct correspondence between key location and character. 
     Information such as language type, special configuration and other important information (such as keyboard type) can be embedded on keyboard membrane  102  using discrete information embedding circuit 126 . Unfortunately, however, the information provided by information embedding circuit 126  is typically used only once at the initialization of keyboard  100  to identify the type of keyboard being used and therefore the version of character map. Once that task has been accomplished, information embedding circuit 126  remains unused thereafter. Therefore since information embedding circuit 126  is used only once and only for the information contained therein, it especially important that the amount of membrane real estate and the number of contacts used to implement information embedding circuit 126  be optimized for the amount of potential information provided. 
     Therefore, an efficient method, apparatus, and system for embedding information in a keyboard membrane is desirable. 
     SUMMARY OF THE DESCRIBED EMBODIMENTS 
     The invention relates to computer peripheral devices. In particular, circuits, systems, and method for embedding information in a keyboard membrane that optimizes the number of contacts, membrane real estate, and amount of information provided therewith. 
     A system for embedding information in a keyboard membrane incorporated in a keyboard assembly is described. The system includes at least the following, a switch matrix having a plurality of column conductors overlaid with a plurality of row conductors and an information embedding circuit integrated with the switch matrix. The information is embedded in the keyboard membrane by permanently connecting a selected one of the plurality of row conductors with the information embedding column conductor. 
     A system for embedding information in a keyboard membrane incorporated in a keyboard assembly is also described. The system includes at least a switch matrix having a plurality of column conductors overlaid with a plurality of row conductors. The system also includes at least an information embedding circuit integrated with the switch matrix. The embedded information is embedded in the keyboard membrane by permanently connecting a selected one of the plurality of column conductors with the information embedding row conductor. 
     A method for embedding information in a keyboard membrane incorporated in a keyboard assembly is described. In the described embodiments, the keyboard membrane includes at least a switch matrix having at least a plurality of column conductors overlaid with a plurality of row conductors and an information embedding circuit integrated with the switch matrix. The method can be carried out by performing at least the following operations. When the information embedding circuit includes an information embedding column line, then connecting a selected one of the plurality of row conductors with the information embedding column line, otherwise when the information embedding circuit includes an information embedding row line, then permanently connecting a selected one of the plurality of column conductors with the information embedding row line. 
     A keyboard membrane is disclosed. The keyboard membrane including at least a switch matrix and a non-binary type keyboard information embedding circuit integrated with the switch matrix for embedding information in the keyboard. 
     An apparatus for efficiently embedding information on a keyboard membrane is disclosed. The keyboard membrane having at least a switch matrix formed of x columns and y rows such that the switch matrix includes a number N contact pads, where N=x×y. The apparatus not being part of the switch matrix, the apparatus having at least a single contact pad and a single conductor electrically connected to the single contact pad. The apparatus embeds information in the keyboard membrane when the single conductor is electrically connected to at least of one of the m rows or at least one of the n columns of the switch matrix such that when the single contact pad is asserted, then the contact pad associated with at least the one of the m row or with the at least one n columns is determined to also be asserted. In one aspect of the described embodiment, the apparatus includes a data capture circuit for capturing which of the at least one m rows or at least n columns is asserted. 
     In another embodiment, a computer readable medium including at least computer program code for accessing information embedded in a keyboard membrane during a keyboard initialization is described. The information can be accessed using an information embedding circuit having at least a cross connected first and second conductor lines. The computer readable medium includes at least computer program code for asserting a contact pad associated with the first conductor line, computer program code for determining an identity of the second conductor line cross connected with the asserted first conductor line, computer program code using the identity of the cross connected second conductor line to access the embedded information, and computer program code for disabling access to the embedded information after the keyboard initialization is successfully completed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is shows a conventional keyboard and keyboard membrane. 
         FIG. 2  shows binary embedding circuit capable of embedding at most four additional information states using at least two contact (information) pins in a keyboard membrane. 
         FIGS. 3A-3D  shows various information embedding circuits in accordance with the embodiments described herein. 
         FIG. 4  shows a keyboard configuration similar to that shown in  FIG. 1  whereby information is embedded in a keyboard membrane using a discrete binary embedding circuit. 
         FIG. 5  shows a keyboard configuration similar to that shown in  FIG. 1  whereby information is embedded in a keyboard membrane using an integrated information embedding circuit in accordance with the described embodiments. 
         FIG. 6  shows a process for embedding and accessing embedded information in a keyboard membrane in accordance with the described embodiments. 
     
    
    
     DETAILED DESCRIPTION OF SELECTED EMBODIMENTS 
     Reference will now be made in detail to selected embodiments an example of which is illustrated in the accompanying drawings. While the invention will be described in conjunction with a preferred embodiment, it will be understood that it is not intended to limit the invention to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the invention as defined by the appended claims. 
     The described embodiments relate to a cost effective system, method and apparatus suitable for embedding information in a keyboard membrane that optimizes the potential amount of information embedded and the required number of contact pins and membrane real estate. 
       FIG. 2  shows binary embedding circuit  200  capable of embedding at most four information states (such as, for example, up to four keyboard types) using at least two contact (information) pins and at least one pin for power and one pin for ground for a total of four pins. For example, binary embedding circuit  200  includes at least four pins, pin V dd  that can be used to provide power, pin GND connected to a ground plane, and information pins A and B each having an associated trace. Using binary embedding circuit  200 , up to at most four information states (shown in logic table  202 ) can be embedded in an associated keyboard membrane. Such information states can be used to, for example, identify the type of keyboard (ANSI, JIS, ISO) being used or any other information deemed appropriate. In order to embed such information, one logic state is selected using option connectors referred to as jumper A and jumper B. As shown, the four logic states represented by logic table  202  can be embedded using binary embedding circuit  200  by variously placing jumper A and jumper B to connect information pin A and information pin B, respectively, to some combination of either V dd  and GND. For example, in order to embed logic state [00], jumper A connects information pin A to GND and jumper B connects information pin B to GND. On the other hand, in order to embed logic state [10], jumper A connects information pin A to V dd  and jumper B connects information pin B to GND. In this way, any of the four logic states [00], [01], [11], and [10] can be embedded using information pins A and B appropriately connected by way of jumper A and jumper B to V dd  and/or GND. Although the option connections are described herein as jumpers, typically they are not discrete components but are connections screened onto membrane  102  along with the other circuits contained thereon. Any extra cost is associated with requiring a larger tail (with more contacts) as well as the need for a larger circuit board for the connector to be soldered. Again, it should be remembered that binary embedding circuit  200  will only be used during keyboard boot up and disabled thereafter making this additional complexity and cost even more irksome. 
     However, no matter how constructed, using binary logic to embed information is not very efficient in terms of the number of contacts used, the amount of membrane real estate required, and the amount of information potentially embedded. As a matter of fact, using binary embedding circuit  200 , the number of available information states (s) is related to the number of information contact pads (n) as Eq(1):
 
s=2 n   Eq (1).
 
In other words, four additional information states requires at least two additional contact pads in order to encode the desired logic and at least two more contact pads, one or power and one for ground.
 
     For example, using binary embedding circuit  200 , embedding four information states (s=4) onto keyboard membrane requires at least four contact pads (two for information pads A,B and one for ground GND and one for power supply V DD ). However, adding a single additional information state for a total of five (s=5) requires the addition of an additional contact pad ((i.e., n=3) over and above those already in use raising the total number of additional contact pads (and their associated traces and contacts) to at least five. Moreover, adding to this relative inefficient use of contact pads and associated traces/contacts is the fact that binary embedding circuit  200  is used only during keyboard initialization. Accordingly, a more efficient method, system and apparatus for embedding information in a keyboard membrane is described herein with regards to the following description and figures. 
       FIG. 3A  shows keyboard  300  having keyboard membrane  302  in accordance with the embodiments described herein. It should be noted that keyboard membrane  302  represents a version of a standard keyboard membrane simplified by reducing the number of rows and columns so as to not obscure the fundamental principles of the described embodiment. For example, a typical keyboard membrane can have eight (8) columns and thirteen (13) rows (and vice versa) with approximately one hundred (100) or so active keys. Accordingly, it is contemplated that any discussion herein pertaining to specific numbers of rows, column, keys, etc. can be scaled up to any appropriate size or type of keyboard or keyboard membrane. It should also be noted that due to the symmetry inherent in the construction and design of keyboard membrane  302 , rows and columns can be considered to be interchangeable and still be considered within the scope and intent of the described embodiments. 
     Unlike conventionally configured keyboard membranes, keyboard membrane  302  does not include a discrete information embedding circuit as described above but rather has column based information embedding circuit  304  integrated with scanning matrix  306 . This integration can be accomplished by, for example, adding an additional column  308  and column contact pad ID. In order to embed information into keyboard membrane  302  using information embedding circuit  304 , a selected row corresponding to the information desired to be embedded is electrically connected (by for example, hard wiring) to column  308 . By asserting column contact pad ID, the corresponding row contact pad will also be asserted. In this way, during a row scanning operation, the identification of which of the row contact pads is an asserted row contact pad, or pads, can be used to access information embedded in keyboard membrane  302 . For example (referring to keyboard type table  310  as the embedded information indicating keyboard type) if keyboard  300  is a JIS type keyboard, hardwiring row  312  to column  308  electrically connects contact pad ID to row contact pad Y 1 . Therefore, during keyboard initialization (or boot up), the asserting of column ID (either HIGH or LOW) results in row contact pad Y 1  also being asserted (either HIGH or LOW). 
     When it is determined that a particular row contact pad has been asserted, this information can be forwarded to keyboard processor  118  for evaluation. In this case, this evaluation can involve keyboard processor  118  querying table  310  and based upon the results of the query, certifying that keyboard  300  is a JIS type keyboard. Once keyboard processor  118  has certified the keyboard type, then keyboard processor  118  can communicate the keyboard type to the system so the system can correctly interpret key presses. The information embedding circuit  304  can be disabled such that it can no longer be accessed or otherwise interfere with the normal operation of keyboard  300 . This disabling can be accomplished in many ways, not the least of which can include, for example, forcing contact pad ID to float (i.e., no electrical connection) thereby eliminating the possibility of the assertion of a signal on column  308 . Therefore, by the addition of a single contact pad (column pad ID) and associated column  308  up to 5 additional information states (corresponding to the 5 row contact pads) can be embedded in keyboard membrane  302 . Compare this to the situation where binary embedding circuit  200  can provide at most 4 additional states using four additional contact pads (pad A and pad B, V dd , GND). 
       FIG. 3B  shows row based information embedding circuit  320  that relies upon the addition of row  322  electrically connected to column  324  to embed the appropriate information in keyboard membrane  302 . In this case, the number of information states s is related to the number of columns c used to embed information as in eq. (2)
 
s=c  Eq (2)
 
where c=number of columns available to be connected to row  322 . Using  FIG. 3B  as the example, up to 5 additional information states can be embedded in keyboard membrane  302  with the additional of a single additional contact pad.
 
     Moreover,  FIG. 3C  illustrates yet another embodiment whereby information embedding circuit  330  where either row  332  or column  334  can be used to embed information in keyboard membrane  302 . For example, if row  332  was used to embed information, then column  334  would be electrically disabled by for example, forcing contact pad Y ID  to float. On the other hand, if column  334  was to be used to embed information, then row  332  would be electrically disabled by, for example, forcing contact pad X ID  to float. For example, if Y ID  is forced to float, electrically connecting column  334  to row  336  can cause pad Y 3  to also be asserted (by going either HIGH or LOW) when pad X ID  is asserted. Of course, due to the symmetry of information embedding circuit  330 , either row  332  or column  334  can be used to embed information in keyboard membrane  302 . 
       FIG. 3D  shows an embodiment of keyboard membrane  302  that provides for concurrent multiple connections between a row and a column. It should be noted, however, that the embodiment shown in  FIG. 3D  can only be employed if the switch matrix design isolates the contact pads and thereby avoiding problems such as phantom key blocking. In this way, the number of information states s that can be embedded into keyboard membrane  302  can be related to the number of rows or columns as in Eq(3)
 
s=2 r , or s=2 c   Eq (3)
 
where r is the number or rows in a row type information embedding circuit as shown in  FIG. 3B  and c is the number of columns in a column type information embedding circuit as shown in  FIG. 3A . For example, in the case shown in  FIG. 3D , (assuming that the number of rows n=5), information embedding circuit  304  in combination with data capture circuit  350  can embed up to thirty two (2 5 ) information states. In the example shown in  FIG. 3D , data word [0 0 1 1 0] can be embedded in keyboard membrane  302  by electrically connecting column  308  to rows  352  and  354 . In this way, when column ID pad is asserted (either HIGH or LOW), then data capture circuit  350  will sense row contact pad Y 1  and row contact pad Y 2  also being asserted.
 
       FIG. 4  shows keyboard arrangement  400  similar to that shown in  FIG. 1  whereby information is embedded in keyboard membrane  402  using discrete binary embedding circuit  200 . As described above, discrete binary embedding circuit  200  requires at least four (4) contact pads (two information contact pads (pad A and pad B), one for ground GND and one for power supply V DD ) and to embed at most four (4) additional information states. In this way, for a keyboard membrane such as that shown in  FIG. 4 , at least 14 contact pads are required along with their associated trace lines which must be accommodated by tail  120 . Since binary embedding circuit  200  is not used after keyboard initialization is completed, the contact pads A, B are no longer used as are the associated trace lines. Keyboard membrane  402  is essentially only using approximately 84% (12/14) available contact pads after initialization. It should be noted, however, that in a more commonly scaled keyboard/keyboard membrane such as described above having eight rows and thirteen columns with twenty six contact pads, the utilization of available contact pads after initialization is approximately 96% (24/26). 
     In any case, the size of tail  120  must be such to accommodate all trace lines that are used at any time (both during and after initialization). Even though the apparently modest increase in tail size in order to accommodate even a single contact can have a substantial impact is the cost in material and time in the manufacture of a large number of keyboards forced to use even a marginally larger tail than would otherwise be necessary. Not only is the cost of manufacturing increased, but the ability to add additional functionality to the keyboard is put in jeopardy if that additional functionally would require an additional contact. 
     However, looking at  FIG. 5  showing keyboard configuration  500  (reproducing the keyboard configuration of  FIG. 3 ), shows that instead of requiring at least 14 contact pads and contacts as with binary embedding circuit  200 , integrating information embedding circuit  304  with switch matrix provides up to 5 additional information states that can be embedded in keyboard membrane  302  using no more than about 13 contact pads. It should be noted, however, that in some embodiments as many as 2 n  (where n=number of rows in a column type information embedding circuit and the number of columns in a row type embedding circuit) information states can be embedded. This additional information can be embedded by essentially keeping track of the state (asserted or not asserted) and the corresponding identification of the respective contact pads (see  FIG. 6  as an example of such a case). Therefore, using integrated information embedding circuit  304  more than doubles (and in some cases, substantially more than doubles) the number of information states that can be embedded in keyboard membrane  302  while necessitating only one additional contact pad as opposed to the at least two required for binary embedding circuit  200 . In this way, information embedding circuit  304  provides substantially more potential information states being embedded into keyboard membrane  304  while at the same time reducing the total contact pad count (and associated contacts) by at least one. 
       FIG. 6  shows a process  600  for embedding and accessing embedded information in a keyboard membrane in accordance with the described embodiments. The process  600  begins at  602  by selecting information to be embedding in the keyboard membrane. Such information can include, for example, a logic state indicative of a keyboard characteristic such as the nature of a character map to be used to identify a character associated with a particular key location. At  604 , an information embedding circuit integrated with a switch matrix on the keyboard membrane is accessed. At  606 , in the case of a column type information embedding circuit having an information embedding column, a row corresponding to the selected information is identified (it should be noted that this same procedure is operable for row type information embedding circuits). At  608 , the identified information is embedded. In the case of a column type information embedding circuit, the embedding is carried out by permanently connecting the identified row and the information embedding column. In this way an assertion of the embedding column also asserts the identified row. In the described embodiments, the embedding can include, for example, hard wiring together the identified row and the information embedding column. At  610 - 614 , the information embedded in keyboard membrane can be accessed by asserting the information embedding column at  610 , reading the asserted row contact pad having a pad identifier at  612 , and using the pad identifier to access the embedded information at  614 . For example, the embedded information can include a look up table that correlates the pad number of the asserted row with a particular keyboard type, such as JIS, ISO, and ANSI. At  616 , the embedding circuitry is disabled. 
     The various aspects, embodiments, implementations or features of the invention can be used separately or in any combination. The invention is preferably implemented by hardware, software or a combination of hardware and software. The software can also be embodied as computer readable code on a computer readable medium. The computer readable medium is any data storage device that can store data which can thereafter be read by a computer system. Examples of the computer readable medium include read-only memory, random-access memory, CD-ROMs, DVDs, optical data storage devices. The computer readable medium can also be distributed over network-coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. 
     While this invention has been described in terms of several preferred embodiments, there are alterations, permutations, and equivalents, which fall within the scope of this invention. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations, and equivalents as fall within the true spirit and scope of the present invention.

Metadata:
Filing Date: 20090605
Publication Date: 20130702
Grant Date: 20130702
Priority Date: 20090605
Inventors: TAN LI-QUAN
WELCH HAROLD J.
LOW WING KONG
BRONSTEIN CHAD
Assignee: APPLE INC
CPC Classifications: [{"code": "H03M11/20", "inventive": true, "first": true, "tree": "[]"}, {"code": "H03M11/20", "inventive": true, "first": true, "tree": "[]"}, {"code": "H03M11/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03M11/02", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 43300348