Data acquisition in a multi-function keyboard system which corrects for preloading of force sensors

• US 5,252,971 A
• Filed: 03/18/1991
• Issued: 10/12/1993
• Est. Priority Date: 09/26/1989
• Status: Expired due to Term

• Current Assignee: Hanger Solutions, LLC (IP Investments Group LLC)
• Original Assignee: Home Row, Inc.
• Inventors: Franz, Patrick J., Biehl, Philip D.
• Primary Examiner(s): Yusko, Donald J.
• Assistant Examiner(s): GIUST, JOHN
• Application Number:
  US07/672,641
• Time in Patent Office: 939 Days
• Field of Search: 341/22, 341/26, 341/34, 341/29, 341/33, 340/706, 340/708, 340/709, 340/710, 340/711, 400/481, 400/485, 364/709.12, 364/709.15, 364/709.16, 200/6 A, 338/114
• US Class Current: 341/26
• CPC Class Codes: G05G 2009/04762 Force transducer, e.g. strain gauge
• CPC Class Codes: G05G 9/047 the controlling member being movable by hand about orthogonal axes, e.g. joysticks for switches H01H25/04
• CPC Class Codes: G06F 3/0213 Arrangements providing an integrated pointing device in a keyboard, e.g. trackball, mini-joystick for pointing devices integrated in a laptop computer G06F1/169; joysticks G05G9/047; constructional details of pointing devices G06F3/033
• CPC Class Codes: G06F 3/023 Arrangements for converting discrete items of information into a coded form, e.g. arrangements for interpreting keyboard generated codes as alphanumeric codes, operand codes or instruction codes
• CPC Class Codes: G06F 3/0338 with detection of limited linear or angular displacement of an operating part of the device from a neutral position, e.g. isotonic or isometric joysticks
• CPC Class Codes: G06F 3/038 Control and interface arrangements therefor, e.g. drivers or device-embedded control circuitry
• CPC Class Codes: G06F 3/0489 using dedicated keyboard keys or combinations thereof
• CPC Class Codes: H01H 13/70 having a plurality of operating members associated with different sets of contacts, e.g. keyboard mounting together a plurality of independent switches H02B
• CPC Class Codes: H01H 13/785 characterised by the material of the contacts, e.g. conductive polymers
• CPC Class Codes: H01H 13/807 characterised by the spatial arrangement of the contact sites, e.g. superimposed sites
• CPC Class Codes: H01H 2003/0293 with an integrated touch switch
• CPC Class Codes: H01H 2201/02 Piezo element
• CPC Class Codes: H01H 2201/036 Variable resistance
• CPC Class Codes: H01H 2221/012 Joy stick type
• CPC Class Codes: H01H 2225/018 Consecutive operations
• CPC Class Codes: H01H 2225/03 Different type of switches
• CPC Class Codes: H01H 2239/006 Containing a capacitive switch or usable as such
• CPC Class Codes: H01H 2239/052 Strain gauge

Abstract

Data acquisition in a multi-function keyboard system includes both acquiring typing data by conventional keyboard scanning techniques and, simultaneously, acquiring pointing data by sampling force sensors coupled to the multi-function pointing key. The keyboard system periodically samples the force sensors to determine bias values defining a null point, and updates the bias values by a moving average calculation to compensate for manufacturing tolerance and long term drift. In response to a start pointing command from the host processor, the keyboard system transmits bias values and then pointing values, the latter being responsive to forces applied to the pointing key by the user for cursor control. The sensor values are encoded so as to pass through to the host processor in a manner transparent to application software. The system scans the force sensors periodically to acquire successive pointing values, and transmits them to the host, as long as pointing mode persists. Concurrently, the keyboard system scans the keyboard to detect other key changes and forwards them to the host as well. The keyswitch data may be interpreted as a pointing event (analogous to a mouse button action), or as an indication to change to typing mode.

Claims

1. A method of acquiring pointing data and alphanumeric typing data in an integrated keyboard coupled to a host processor, the keyboard having an array of typing keyswitches including a multi-purpose pointing key and a plurality of force sensors coupled to the pointing key, the method comprising the steps of:

providing means in the keyboard for selecting one at a time of a typing mode of operation for acquiring typing data and a pointing mode of operation for acquiring pointing data;

when the keyboard is not in pointing mode, periodically scanning each of the force sensors to acquire a corresponding analog force sensor bias value; and

deducting each force sensor bias value from the corresponding force sensor pointing value acquired during a pointing operation to determine respective new force values, thereby correcting for preloading of the force sensors.

2. A method according to claim 1 including:

storing the force sensor bias values;

periodically repeating said scanning to acquire new force sensor bias values; and

after each scan of the force sensors to acquire new bias values, updating the stored force sensor bias values in response to the new bias values.

3. A method according to claim 2 wherein said updating step includes computing a running average of each force sensor bias value, and replacing each of the stored force sensor bias values by the corresponding running average, thereby correcting the stored bias values for long-term drift and temperature sensitivity of the force sensors.

4. A method according to claim 3 wherein said computing each running average includes ignoring a new bias value that varies by more than a predetermined percentage from the corresponding running average bias value.

5. A method according to claim 1 wherein periodically scanning the force sensors includes:

monitoring a timer interrupt input to detect periodic timer interrupt signals; and

pacing said scanning step by counting the timer interrupt signals during typing mode, thereby scanning the force sensors in typing mode at a second predetermined frequency proportional to the timer interrupt signal frequency.

6. A method according to claim 1 wherein said scanning the force sensors is repeated periodically in a range of up to approximately every 15 minutes.

7. A method of acquiring pointing direction data, mouse button emulation data and alphanumeric typing data in an integrated keyboard coupled to a host processor, the keyboard having an array of typing keyswitches including a multi-purpose pointing key and a plurality of force sensors coupled to the pointing key, the method comprising the steps of:

providing means in the keyboard for selecting one at a time of a typing mode of operation for acquiring typing data and a pointing mode of operation for acquiring pointing data, wherein pointing data includes both pointing direction data and mouse button emulation data;

for each force sensor, storing a respective bias value in the keyboard;

regardless of the selected mode of operation, periodically scanning the force sensors to acquire respective force sensor values;

during the typing mode of operation, updating the stored bias values responsive to the acquired force sensor values without transmitting the acquired force sensor values to the host processor;

during the pointing mode of operation, transmitting the acquired force sensor values to the host processor as pointing direction data for cursor control, without updating the stored bias values;

regardless of the selected mode of operation, periodically scanning the keyswitch array to detect a change in keyswitch state, so that keyswitch actions are captured even while pointing with the pointing key; and

if a change in keyswitch state is detected, transmitting a keycode representative of the detected keyswitch state change to the host processor, so that the transmitted keycodes may be used as typing data in the typing mode of operation and may be used to emulate mouse button actions in the pointing mode of operation, whereby the integrated keyboard obviates a separate mouse.

8. A method according to claim 7 further comprising:

providing a scan flag to schedule acquisition of force sensor data;

providing a bias flag to schedule updating the stored bias values;

periodically setting the scan flag at a predetermined frequency to indicate time to scan the force sensors, thereby periodically acquiring current force sensor values;

after each scan of the keyswitch array, checking the scan flag for an indication to scan the force sensors;

if the scan flag does not indicate time to scan the force sensors, repeating said scanning the keyswitch array;

checking the bias flag for an indication of whether to update the stored bias values; and

if the bias flag does indicate time to update the stored bias values, updating each of the stored bias values responsive to the corresponding current force sensor value without transmitting the current force sensor values to the host processor.

9. A method according to claim 7 wherein said selecting means includes a mode flag and providing a scan flag to schedule acquisition of force sensor data includes:

providing a mode flag in the keyboard for indicating one of a typing mode and a pointing mode of operation of the keyboard;

providing a scan timer for tracking elapsed time;

providing a periodic timer interrupt signal at a predetermined frequency;

responsive to each timer interrupt signal, if the keyboard is not then transmitting data to the host processor, checking the state of the mode flag to determine a current mode of operation;

if the current mode is pointing, decrementing the scan timer;

checking the scan timer to detect a predetermined time limit; and

if the time limit is detected, setting the scan flag to initiate scanning the force sensors and clearing the bias flag, thereby indicating that acquired force sensor data is to be transmitted to the host processor.

10. A method according to claim 9 further comprising:

providing a bias timer for tracking elapsed time;

responsive to each timer interrupt signal, if the current mode is typing, decrementing the bias timer and checking the bias timer to detect a predetermined time limit; and

if the time limit is detected, setting the scan flag to initiate scanning the force sensors and setting the bias flag to indicate that acquired force sensor data be used to update the stored bias values and not transmitted to the host processor.

11. A method according to claim 7 further comprising:

providing a mode flag in the keyboard for indicating one of a typing mode and a pointing mode of operation of the keyboard;

responsive to a communication interrupt signal from the host processor, receiving a command from the host processor;

if the received command is a predetermined start pointing command, setting the mode flag to enter the pointing mode of operation and enqueuing a bias packet of data for transmission to the host processor, the bias packet of data comprising the stored force sensor bias values, so that the host processor can deduct the stored bias values from current force sensor values subsequently transmitted to the host processor.

12. A method according to claim 11 further comprising:

responsive to the start pointing command, periodically setting the scan flag at a first predetermined frequency, thereby initiating periodic scanning of the force sensors at the first frequency; and

clearing the bias flag so that current force sensor data will be transmitted to the host processor.

13. A method according to claim 11 further comprising:

if the received command is a predetermined stop pointing command, setting the mode flag to enter the typing mode of operation and setting the bias flag for updating the stored bias values during the typing mode of operation.

14. A method according to claim 11 further comprising continuing during the pointing mode of operation to scan the keyswitch array and to transmit keycodes to the host processor identifying keyswitch state changes, thereby allowing keyswitches in the array to be used for emulating mouse buttons for clicking and dragging operations.

15. A method according to claim 7 wherein the integrated keyboard is coupled to the host processed through a keyboard port, and further comprising the steps of:

responsive to a communication interrupt signal from the host processor, receiving a command from the host processor;

if the received command is a predetermined identify command, enqueing a keyboard identification data packet for transmission to the host processor, the identification data packet comprising

an indication that the keyboard is an integrated keyboard;

a keyboard software version identification number; and

an indication of the number of force sensors coupled to the pointing key and their geometric configuration; and

wherein the keyboard software version identification number is offset by a predetermined binary offset, the offset being selected so that the keyboard port does not attempt to remap the keyboard software version number before providing it to the host processor.

16. A method according to claim 15 wherein the identification data packet further includes identification of a keyswitch immediately to the left of the letter-A key in the keyboard array, so that the said keyswitch to the left of the letter-A key may be recognized by the host processor for explicit mode change operations.

17. An integrated keyboard for acquiring both typing and pointing data, the keyboard comprising:

an array of keyswitches, one of the keyswitches being designated as a pointing key for both typing and pointing operations;

a plurality of force sensors coupled to the pointing key to sense forces applied to the pointing key by a user;

microcontroller means in the keyboard for both typing and pointing data acquisition, the microcontroller means having a built-in A/D converter and A/D input for receiving an input voltage for conversion to digital data;

the microcontroller means further including a plurality of scan lines coupled to the array for scanning the array;

means coupling a predetermined one of the keyboard scan lines to each of the force sensors for selectively enabling the force sensors, one at a time, under control of the microcontroller means, so as to provide a corresponding input voltage to the A/D input during the pointing mode of operation;

memory means coupled to the microcontroller means for storing a respective force sensor bias value for each one of the force sensors;

software means for controlling the keyboard microcontroller means so as to periodically scan the force sensors and read the A/D converter to acquire corresponding force sensor values during the typing mode of operation, thereby acquiring bias values for each of the force sensors; and

means for writing the bias values into the memory means as stored bias values.

18. An integrated keyboard according to claim 17 further comprising:

means responsive to the pointing mode of operation for reading the A/D converter to acquire corresponding force sensor values and for encoding each of the force sensor values so as to prevent subsequent remapping of the force sensor values by a host computer keyboard communications port;

communication means for operatively connecting the integrated keyboard to a host computer; and

means responsive to the pointing mode of operation for transmitting the encoded force sensor values to a host computer over the communication means as a series of bytes, each byte being a representation of a respective one of the encoded force sensor values; and

means for transmitting detected keyswitch state changes to the host computer over the same communication means during both modes of operation, so that keyswitch state changes detected during the pointing mode of operation may be used by the host computer to emulate mouse button state changes, whereby all of the keyswitches in the keyboard are available for mouse button emulation.