Systems and methods for implementing pressure sensitive keyboards

1. A keyboard system, comprising:

one or more pressure sensitive keys configured to provide analog output signals corresponding to each given one of the pressure sensitive keys that is representative of the given amount of pressure being currently applied to the given key; and

pressure sensing interface circuitry coupled to receive the analog output signal from each given one of the pressure sensitive keys, the pressure-sensing interface circuitry being configured to provide a corresponding separate toggled alternating open and short on/off digital output signal based thereupon having a frequency alternating between on and off that is representative of the given amount of pressure being currently applied to the corresponding given one of the pressure sensitive keys by:

sensing in real time pressure applied to each given one of the pressure sensitive keys,

identifying a pressure sensitive key presently being pressed,

determining a degree of pressure being applied to the presently-pressed pressure sensitive key,

providing a separate toggled alternating open and short on/off digital output signal by toggling a digital output signal corresponding to the identity of the presently-pressed pressure sensitive key to emulate the action of a user's finger repeatedly pressing a conventional digital key with a rate that is relative to the pressure being applied to the presently-pressed pressure sensitive key, and

monitoring and reevaluating the degree of pressure being applied to the presently-pressed pressure sensitive key and outputting an updated toggled digital output signal for as long as the presently-pressed pressure sensitive key remains pressed.

2. The keyboard system of claim 1 , wherein the pressure sensing interface circuitry further comprises:

pressure-sensing digital output circuitry coupled to receive the analog output signal from each given one of the pressure sensitive keys, the pressure-sensing digital output circuitry being configured to provide a separate alternating high and low (high/low) digital output signal based thereupon having a frequency alternating between high and low that is representative of pressure applied to each given corresponding one of the pressure sensitive keys; and

switching circuitry configured to receive each of the alternating high/low digital output signals and to provide the separate alternating open/short on/off digital output signal having a frequency alternating between on and off that is representative of pressure applied to each corresponding given one of the pressure sensitive keys.

3. The keyboard system of claim 1 , wherein the pressure sensing interface circuitry includes falling edge-triggered digital interrupt inputs coupled to receive the analog output signals from each given one of the pressure sensitive keys.

4. The keyboard system of claim 1 , wherein the pressure sensing interface circuitry is further configured for coupling to provide the separate alternating open/short on/off digital output signal corresponding to each given pressure sensitive key being currently pressed to a respective column/row intersection of a legacy keyboard key matrix that corresponds to the given pressure sensitive key being currently pressed, the legacy keyboard matrix being operably coupled to a legacy keyboard controller having no analog input circuitry.

5. The keyboard system of claim 4 , further comprising a keyboard device body that includes the pressure sensing interface circuitry; wherein the keyboard device body is configured to be mechanically coupled as a drop-in keyboard to an information handling system chassis that includes the legacy keyboard controller.

6. The keyboard system of claim 5 , wherein the information handling system is a notebook computer.

7. The keyboard system of claim 4 , wherein the pressure sensing interface circuitry further comprises an integrated circuit including a microcontroller, the microcontroller having falling edge-triggered digital interrupt inputs for receiving the pressure sensitive analog signals from the pressure sensitive keys; wherein the legacy keyboard controller further comprises an I/O interface that interfaces with the legacy keyboard key matrix; and wherein each column/row intersection of the legacy keyboard key matrix accommodates an open or short of column/row signals corresponding to a given respective pressure sensitive key being currently pressed by receiving the alternating open/short digital output signal signals from the pressure sensing interface circuitry that corresponds to the given pressure sensitive key being currently pressed.

8. The keyboard system of claim 1 , wherein each of the plurality of pressure sensitive keys is further configured to produce a variable capacitance analog signal when depressed by a user.

9. The keyboard system of claim 8 , wherein each of the plurality of pressure sensitive keys further comprises a flexible and conductive half-dome structure positioned underneath a keycap.

10. The keyboard system of claim 8 , wherein the pressure sensing interface circuitry is further configured to generate a count associated with the capacitance measurement of each given key, the count being utilized to represent pressure applied to the given pressure sensitive key; and to produce the separate alternating open/short digital output signal based upon the generated count having a frequency alternating between on and off that is representative of pressure applied to the corresponding given one of the pressure sensitive keys.

11. The keyboard system of claim 8 , where each of the plurality of pressure sensitive keys further comprises a capacitive plate and is further configured to produce a variable capacitance analog signal when depressed by a user; and where the pressure sensing interface circuitry is further configured to determine a degree of pressure being applied to the identified presently-pressed pressure sensitive key by measuring a capacitive discharge timer count of the capacitive plate of the presently-pressed pressure sensitive key.

12. The keyboard system of claim 11 , where the pressure sensing interface circuitry is further configured to: provide multiple pre-defined levels of different alternative toggle rate frequency that correspond to different pre-defined capacitive discharge timer count ranges; monitor and reevaluate the timer count value of the presently-pressed pressure sensitive key and output an updated toggled digital output signal having a pre-defined toggle rate frequency that corresponds to one of the different pre-defined timer count ranges for as long as the presently-pressed pressure sensitive key remains pressed.

13. The keyboard system of claim 1 , further comprising a keyboard device body that includes the one or more pressure sensitive keys and a plurality of digital keys within the keyboard device body, each of the digital keys being coupled to provide a single open/short digital output signal each time the digital key is pressed by a user.

14. The keyboard system of claim 13 , wherein the pressure sensing interface circuitry is further configured for coupling to provide the separate alternating open/short on/off digital output signal corresponding to each given pressure sensitive analog key of the keyboard device body to a respective column/row intersection of a common legacy keyboard key matrix that corresponds to the given pressure sensitive key being currently pressed and to monitor and reevaluate the degree of pressure being applied to the presently-pressed pressure sensitive key and output an updated toggled digital output signal to the respective column/row intersection of the common legacy keyboard key matrix for as long as the presently pressed pressure sensitive key remains pressed; wherein each of the digital keys of the keyboard device body is further configured for coupling to provide the single open/short digital output signal to the same common legacy keyboard matrix that receives the alternating open/short on/off digital output signals from the pressure sensing interface circuitry; and wherein the legacy keyboard matrix is operably coupled to a legacy keyboard controller having no analog input circuitry.

15. The keyboard system of claim 1 , wherein the pressure sensing interface circuitry coupled is further configured to provide the corresponding separate toggled alternating open and short on/off digital output signal corresponding to each given one of the pressure sensitive analog keys in a manner that emulates toggling of a conventional momentary off/on digital key and to monitor and reevaluate the degree of pressure being applied to the presently-pressed pressure sensitive key and outputting an updated toggled digital output signal for as long as the presently-pressed pressure sensitive key remains pressed and without requiring toggling of the given key to which pressure is being applied.

16. The keyboard system of claim 1 , wherein the pressure sensing interface circuitry is further configured to continue: providing the corresponding separate toggled alternating open and short on/off digital output signal corresponding to each given one of the pressure sensitive analog keys and outputting the updated toggled digital output signal corresponding to each given one of the pressure sensitive analog keys for as long as each given one of the presently-pressed pressure sensitive keys remains pressed.

17. The keyboard system of claim 1 , wherein the pressure sensing interface circuitry is further configured to:

continue providing the corresponding separate toggled alternating open and short on/off digital output signal corresponding to a first one of the pressure sensitive analog keys at a first alternating on/off frequency that is representative of a first amount of pressure being currently applied to the corresponding first one of the pressure sensitive keys; and

then in response to a change in pressure currently applied to the first one of the pressure sensitive analog keys to provide a corresponding separate toggled alternating open and short on/off digital output signal corresponding to the first one of the pressure sensitive analog keys at a second and different alternating on/off frequency that is representative of a second and different amount of pressure being currently applied to the corresponding first one of the pressure sensitive keys by monitoring and reevaluating the degree of pressure being applied to the presently pressed first one of the pressure sensitive keys and outputting an updated toggled digital output signal for as long as the presently-pressed first one of the pressure sensitive keys remains pressed.

18. The keyboard system of claim 1 , where the pressure sensing interface circuitry is further configured to provide a corresponding separate toggled alternating open and short on/off digital output signal having an alternating toggle rate frequency of at least one of about 20 times/second, about 16 times/second, or about 8 times/second.

19. A method of accepting user input from a keyboard, comprising:

providing one or more pressure sensitive keys;

producing an analog output signal for each given one of the pressure sensitive keys when when the given one of the pressure sensitive keys is depressed by a user, the analog output signals being representative of the given amount of pressure being currently applied to the given pressure sensitive key by the user; and

providing a corresponding separate toggled alternating open and short (open/short) on/off digital output signal based upon the analog output signal by:

sensing in real time pressure applied to each given one of the pressure sensitive keys,

identifying a pressure sensitive key presently being pressed,

determining a degree of pressure being applied to the presently-pressed pressure sensitive key,

providing the separate toggled alternating open and short on/off digital output signal by toggling a digital output signal corresponding to the identity of the presently-pressed pressure sensitive key to emulate the action of a user's finger repeatedly pressing a conventional digital key with a rate that is relative to the pressure being applied to the presently-pressed pressure sensitive key, and

monitoring and reevaluating the degree of pressure being applied to the presently-pressed pressure sensitive key and outputting an updated toggled digital output signal for as long as the presently-pressed pressure sensitive key remains pressed;

where the alternating open and short (open/short) on/off digital output signal has a frequency alternating between on and off that is representative of the given amount of pressure being currently applied to the given pressure sensitive key by the user.

20. The method of claim 19 , further comprising:

providing pressure-sensing digital output circuitry;

providing switching circuitry;

receiving the analog output signal from each given one of the pressure sensitive keys in the pressure-sensing digital output circuitry;

providing a separate alternating high and low (high/low) digital output signal from the pressure-sensing digital output circuitry, each separate alternating high/low digital output signal being based upon a corresponding received analog output signal and having an alternating high/low frequency alternating between high and low that is representative of pressure applied to each given corresponding one of the pressure sensitive keys; and

receiving each of the alternating high/low digital output signals in the switching circuitry; and

providing the separate alternating open/short digital output signal from the switching circuitry, each separate alternating open/short digital output signal having a frequency alternating between on and off that is representative of pressure applied to a corresponding given one of the pressure sensitive keys.

21. The method of claim 20 , further comprising providing a keyboard device body that includes pressure sensing interface circuitry; providing an information handling system chassis that includes a legacy keyboard key matrix having column/row intersections coupled to a legacy keyboard controller having no analog input circuitry; mechanically coupling the keyboard device body as a drop-in keyboard to the information handling system chassis; and providing the separate alternating open/short on/off digital output signal corresponding to each given pressure sensitive key being currently pressed from the switching circuitry to a respective column/row intersection of the legacy keyboard key matrix that corresponds to the given pressure sensitive key being currently pressed and outputting the updated toggled digital output signal to the respective column/row intersection of the legacy keyboard key matrix for as long as the presently-pressed pressure sensitive key remains pressed.

22. The method of claim 21 , wherein the information handling system is a notebook computer.

23. The method of claim 20 , further comprising providing an information handling system chassis that includes a legacy keyboard key matrix having column/row intersections coupled to a legacy keyboard controller comprising a separate microcontroller having an I/O interface that interfaces with the legacy keyboard key matrix, the legacy keyboard controller having no analog input circuitry; providing the pressure-sensing interface circuitry as an integrated circuit including a microcontroller, the microcontroller having falling edge-triggered digital interrupt inputs for receiving the pressure sensitive analog signals from the pressure sensitive keys; providing the separate alternating open/short digital on/off output signal corresponding to each pressure sensitive key to the column/row intersection of the legacy keyboard key matrix that corresponds to the given pressure sensitive key being currently pressed; accommodating an open or short of corresponding column/row signals in the legacy keyboard key matrix in response to receiving the alternating open/short digital output signal corresponding to the given pressure sensitive key being currently pressed and outputting the updated toggled digital output signal that corresponds to the given pressure sensitive key being currently pressed for as long as the presently-pressed pressure sensitive key remains pressed.

24. The method of claim 19 , further comprising processing each of the analog output signals from each given one of the pressure sensitive keys with a falling edge event driven interrupt.

25. The method of claim 19 , wherein the plurality of pressure sensitive keys is each a key further configured to produce a variable capacitance analog signal when depressed by a user; and wherein the method further comprising producing a variable capacitance analog signal for each given one of the pressure sensitive keys when depressed by a user.

26. The method of claim 25 , wherein the plurality of pressure sensitive keys each further comprises a flexible and conductive half-dome structure positioned underneath a keycap.

27. The method of claim 25 , further comprising generating a count associated with the capacitance measurement of each given pressure sensitive key and being utilized to represent pressure applied to the given pressure sensitive key; and producing the separate alternating open/short digital output signal based upon the generated count having a frequency alternating between on and off that is representative of pressure applied to the corresponding given one of the pressure sensitive keys.

28. The method of claim 19 , further comprising providing a keyboard device body that includes the one or more pressure sensitive keys and a plurality of digital keys within the keyboard device body; and providing a single open/short digital output signal from each given digital key each time the given digital key is pressed by a user.

29. The method of claim 28 , further comprising:

providing the separate alternating open/short on/off digital output signal corresponding to each given pressure sensitive analog key of the keyboard device body from the pressure sensing interface circuitry to a respective column/row intersection of a common legacy keyboard key matrix that corresponds to the given pressure sensitive key being currently pressed and outputting the updated toggled digital output signal to the respective column/row intersection of the common legacy keyboard key matrix;

providing the single open/short digital output signal from each given digital key to the same common legacy keyboard matrix that receives the alternating open/short on/off digital output signals from the pressure sensing interface circuitry; and

providing respective output signals corresponding to each given respective one of the pressure sensitive analog keys and each given one of the respective digital keys from the common legacy keyboard key matrix to a legacy keyboard controller when the corresponding individual analog and digital keys are depressed by a user, the legacy keyboard controller having no analog input circuitry.

30. The method of claim 19 , further comprising providing the corresponding separate toggled alternating open and short on/off digital output signal corresponding to each given one of the pressure sensitive analog keys being depressed by a user in a manner that emulates toggling of a conventional momentary off/on digital key without requiring the user to toggle the given key being depressed by the user.

31. The method of claim 19 , further comprising continuing to: provide the corresponding separate toggled alternating open and short on/off digital output signal corresponding to each given one of the pressure sensitive analog keys and output the updated toggled digital output signal corresponding to each given one of the pressure sensitive analog keys for as long as each given one of the presently-pressed pressure sensitive keys remains pressed.

32. The method of claim 19 , further comprising:

continuing to provide the corresponding separate toggled alternating open and short on/off digital output signal corresponding to a first one of the pressure sensitive analog keys at a first alternating on/off frequency that is representative of a first amount of pressure being currently applied to the corresponding first one of the pressure sensitive keys and to monitor and reevaluate the degree of pressure being applied to the presently-pressed first one of the pressure sensitive keys and output an updated toggled digital output signal for as long as the presently pressed first one of the pressure sensitive keys remains pressed;

producing a change in the analog output signal from the first one of the pressure sensitive keys in response to a change in the amount of pressure currently applied to the first one of the pressure sensitive keys by the user from the first pressure to a second and different pressure; and

in response to the change in pressure currently applied to the first one of the pressure sensitive analog keys by the user, providing a corresponding separate toggled alternating open and short on/off digital output signal corresponding to the first one of the pressure sensitive analog keys at a second and different alternating on/off frequency that is representative of a second and different amount of pressure being currently applied to the corresponding first one of the pressure sensitive keys by monitoring and reevaluating the degree of pressure being applied to the presently-pressed first one of the pressure sensitive keys and outputting an updated toggled digital output signal for as long as the presently-pressed first one of the pressure sensitive keys remains pressed.